JP6986113B2 - Equipment and computer readable storage media for providing modified periodic voltage functions to electrical nodes - Google Patents

Description

(Related application and priority)
This application is a partial continuation of US Patent Application No. 13 / 193,299 (filed July 28, 2011) and US Non-Provisional Patent Application No. 12 / 870,837 (filed April 29, 2010). ) Is a partial continuation application. The details of Applications 13 / 193, 299, 12 / 870, 837 are hereby incorporated by reference in their entirety for all purposes.

(Technical field)
The present invention generally relates to plasma processing. In particular, without limitation, the invention relates to methods and devices for plasma-assisted etching, deposition, and / or other plasma-assisted processes.

Many types of semiconductor devices are machined using plasma-based etching techniques. If it is a conductor that is etched, a negative voltage is applied to the conductive board with respect to ground so that a substantially uniform negative voltage is generated over the surface of the board conductor, and the negative voltage is The positive ions that attract the positively charged ions towards the conductor and thus affect the conductor have substantially the same energy.

However, if the substrate is dielectric, the invariant voltage is not effective because it applies a voltage over the entire surface of the substrate. However, an AC voltage (eg, high frequency) can be applied to the conductive plate (or chuck) so that the AC field induces a voltage on the surface of the substrate. During a positive AC half cycle, the substrate attracts light electrons compared to the mass of the cations. Therefore, many electrons will be attracted to the surface of the substrate during the positive cycle portion. As a result, the surface of the substrate will be negatively charged, resulting in the ions being attracted towards the negatively charged surface. Also, when the ions collide with the surface of the substrate, the collision removes the material from the surface of the substrate, i.e. results in etching.

In many cases it is desirable to have a narrow ion energy distribution, but applying a sinusoidal waveform to the substrate induces a wide distribution of ion energy, which results in the desired etching cross section. Limit the capacity of the plasma process. Known techniques for achieving narrow ion energy distribution are expensive, inefficient, difficult to control, and can adversely affect plasma density. As a result, these known techniques have not been adopted for commercial use. Therefore, there is a need for systems and methods that solve the shortcomings of current technology and provide other new and innovative features.

Illustrative embodiments of the invention, shown in the drawings, are summarized below. These and other embodiments are fully described in the section of embodiments for carrying out the invention. However, it should be understood that it is not intended to limit the invention to the embodiments described in the disclosure of the invention or the embodiments for carrying out the invention. One of ordinary skill in the art may recognize that there are numerous modifications, equivalents, and alternative structures that fall within the spirit and scope of the invention set forth in the claims.

According to one embodiment, the invention can be characterized as a method of establishing one or more plasma sheath voltages. The method may include providing a modified periodic voltage function to the substrate support of the plasma chamber. The substrate support can be coupled to a substrate configured for processing in the plasma. Also, the modified periodic voltage function can include the modified periodic voltage function by the ion current compensation Ic. The modified periodic voltage function can include a pulse and a portion between the pulses. Also, the pulse can be a function of the periodic voltage function, and the slope of the portion between the pulses can be a function of the ion current compensation Ic. The method can further include accessing at least an effective capacitance value C _{1 representing the capacitance of the substrate support.} The method can finally identify the value of the ion current compensation Ic, which will result in a defined ion energy distribution function of the ions reaching the surface of the substrate, the identification of the portion between the pulses. It is a function of effective capacity C ₁ and slope dV _{0 / dt.}

According to another embodiment, the invention can be described as a method of biasing the plasma to achieve defined ion energy at the surface of the substrate in the plasma processing chamber. The method may include applying a modified periodic voltage function to the substrate support with a modified periodic voltage function by ion current compensation. The method may further include sampling at least one cycle of the modified periodic voltage function to generate voltage data points. The method may further include estimating the value of the first ion energy on the substrate surface from voltage data points. The method may also include adjusting the modified periodic voltage function until the first ion energy is equal to the defined ion energy.

According to yet another embodiment, the invention can be characterized as a method of achieving an ion energy distribution function width. The method may include providing a modified periodic voltage function to the substrate support of the plasma processing chamber. The method may further include sampling at least two voltages from the non-sinusoidal waveform in the first time and the second time. The method can additionally include calculating the slopes of at least two voltages as dV / dt. The method may also include comparing the slope with a reference slope known to correspond to the width of the ion energy distribution function. Ultimately, the method may include adjusting the modified periodic voltage function so that the slope approaches the reference slope.

Another aspect of the present disclosure can be characterized as a device comprising a power supply, an ion current compensating component, and a controller. The power supply unit can provide a periodic voltage function having a pulse and a portion between the pulses. The ion current compensation component can modify the slope of the portion between the pulses to form a modified periodic voltage function. The modified periodic voltage function can be configured to provide to the substrate support for processing within the plasma processing chamber. The controller can be coupled to the switch mode power supply and ion current compensation components. The controller can also be configured to identify the value of ion current compensation that, when provided to the substrate support, will result in a defined ion energy distribution function of the ions reaching the surface of the substrate. ..

Yet another aspect of the present disclosure is a non-transient tangible computer read encoded by a processor readable instruction for performing a method of monitoring the ion current of a plasma configured to process the substrate. It can be characterized as a possible storage medium. The method samples a modified periodic voltage function with an ion current compensation having a first value and a modified periodic voltage function with an ion current compensation having a second value. Can include sampling. The method can further include determining the slope of the modified periodic voltage function as a function of time based on the first and second samplings. The method also determines the slope of the periodic voltage function modified as a function of time based on the first and second samplings. The method finally calculates a third value of ion current compensation, based on the slope, that a constant voltage on the substrate will be present for at least one cycle of the modified periodic voltage function. Can include doing.

項目１に記載の方法。
（項目５）
前記イオン電流補償Ｉｃを第１の値に設定することと、
前記関数ｆの符号を決定することと、
前記関数ｆの符号が正である場合、前記イオン電流補償Ｉｃを増加させ、前記関数ｆの符号が負である場合、前記イオン電流補償Ｉｃを減少させることと
をさらに含む、項目４に記載の方法。
（項目６）
前記識別することは、２つ以上の時間に前記パルス間の前記部分の電圧をサンプリングすることを含む、項目１に記載の方法。
（項目７）
前記識別することは、前記２つ以上の時間にサンプリングされた前記電圧から、前記傾きｄＶ_０／ｄｔを計算することを含む、項目６に記載の方法。
（項目８）
前記識別することは、前記修正された周期的電圧関数の２つ以上のサイクルに対して前記傾きｄＶ_０／ｄｔを計算することを含み、前記２つ以上のサイクルの各々は、前記イオン電流補償Ｉｃの異なる値に関連付けられている、項目７に記載の方法。
（項目９）
前記識別することは、第１のサイクル中および第２のサイクル中に、前記パルス間の前記部分の電圧をサンプリングすることと、少なくともこれらのサンプリングされた電圧から前記傾きｄＶ_０／ｄｔを計算することとを含む、項目６に記載の方法。
（項目１０）
前記イオン電流補償Ｉｃは、前記プラズマのプラズマシースを横切るイオン電流Ｉ_Ｉに直線的に関連している、項目１に記載の方法。
（項目１１）
前記イオン電流補償Ｉｃは、以下の方程式に従って、前記イオン電流Ｉ_Ｉに直線的に関連し、

Ｃ_１は、バイアス供給部によって見られる前記プラズマチャンバの有効容量であり、Ｃ_{ｓｔｒａｙ}は、前記バイアス供給部によって見られる前記プラズマチャンバの累積浮遊容量である、項目１０に記載の方法。
（項目１２）
前記有効容量Ｃ_１は、時間変動する、項目１１に記載の方法。
（項目１３）
前記イオン電流補償Ｉｃは、時間変動する、項目１１に記載の方法。
（項目１４）
イオンが第１のイオンエネルギーを伴って前記基板の前記表面に到達するように、前記修正された周期的電圧関数を前記基板支持部に提供することをさらに含む、項目１に記載の方法。
（項目１５）
前記修正された周期的電圧関数は、前記第１のイオンエネルギーに対応する第１の電圧ステップを有する、項目１４に記載の方法。
（項目１６）
前記イオン電流補償Ｉｃの第２の値を伴う前記修正された周期的電圧関数を前記基板支持部に提供し、前記イオンエネルギー分布関数を拡大することをさらに含む、項目１５に記載の方法。
（項目１７）
前記第１の電圧ステップおよび前記第２の電圧ステップは、前記修正された周期的電圧関数の隣接したサイクルにおいて提供される、項目１５に記載の方法。
（項目１８）
前記提供することは、前記プラズマの密度に無視可能な影響を及ぼす、項目１４に記載の方法。
（項目１９）
プラズマ処理チャンバ内の基板の表面において定義されたイオンエネルギーを達成するようにプラズマにバイアスをかける方法であって、前記方法は、
イオン電流補償によって修正された周期的電圧関数を備えている修正された周期的電圧関数を基板支持部に印加することと、
前記修正された周期的電圧関数の少なくとも１つのサイクルをサンプリングし、電圧データ点を生成することと、
前記電圧データ点から前記基板表面における第１のイオンエネルギーの値を推定することと、
前記第１のイオンエネルギーが前記定義されたイオンエネルギーに等しくなるまで、前記修正された周期的電圧関数を調節することと
を含む、方法。
（項目２０）
前記調節の各電圧増分後、前記修正された周期的電圧関数の少なくとも１つのサイクルをサンプリングして、前記第１のイオンエネルギーの前記値を計算することをさらに含む、項目１９に記載の方法。
（項目２１）
前記推定することは、入力としてのイオン電流の関数である、項目１９に記載の方法。（項目２２）
前記イオン電流は、前記イオン電流補償の関数である、項目２１に記載の方法。
（項目２３）
以下の方程式は、前記第１のイオンエネルギーの値を推定することにおいて使用され、

ΔＶは、前記電圧ステップであり、Ｃ_１は、バイアス供給部によって見られる前記チャンバの有効容量であり、Ｃ_{ｓｈｅａｔｈ}は、前記プラズマシースのシース容量であり、前記イオン電流に依存する、項目２２に記載の方法。
（項目２４）
前記調節することは、前記第１のイオンエネルギーが前記定義されたイオンエネルギーに等しくなるまで、前記修正された周期的電圧関数の前記ステップ電圧ΔＶを調節することを含む、項目２３に記載の方法。
（項目２５）
前記イオン電流補償の第１の値を第２の値に変化させ、前記イオンエネルギーの分布の幅を拡大することをさらに含む、項目１９に記載の方法。
（項目２６）
前記印加することおよび前記調節することは、前記プラズマのプラズマ密度に無視可能な影響を及ぼす、項目１９に記載の方法。
（項目２７）
前記調節することは、前記第１のイオンエネルギーが前記定義されたイオンエネルギーに等しくなるまで、バイアス供給部電圧を調節することを含む、項目１９に記載の方法。（項目２８）
イオンエネルギー分布関数幅を達成する方法であって、前記方法は、
修正された周期的電圧関数をプラズマ処理チャンバの基板支持部に提供することと、
第１の時間および第２の時間において、非正弦波形から少なくとも２つの電圧をサンプリングすることと、
前記少なくとも２つの電圧の傾きをｄＶ／ｄｔとして計算することと、
前記傾きをイオンエネルギー分布関数幅に対応することが分かっている基準傾きと比較することと、
前記傾きが前記基準傾きに接近するように、前記修正された周期的電圧関数を調節することと
を含む、方法。
（項目２９）
前記第１の時間は、前記修正された周期的電圧関数の第１のサイクルの間に起こり、前記第２の時間は、前記修正された周期的電圧関数の第２のサイクルの間に起こる、項目２８に記載の方法。
（項目３０）
前記第１および第２の時間は、前記修正された周期的電圧関数の同一のサイクルの間に起こる、項目２８に記載の方法。
（項目３１）
前記サンプリングすることは、少なくとも４００ｋＨｚのサンプリングレートで行われる、項目２８に記載の方法。
（項目３２）
プラズマを含むように構成されているプラズマ処理チャンバと、
前記プラズマ処理チャンバ内に位置付けられ、プラズマ処理中、基板を支持するように配置されている基板支持部と、
周期的電圧関数を前記基板支持部に提供する電力供給部であって、前記周期的電圧関数は、パルスと前記パルス間の部分とを有する、電力供給部と、
前記パルス間の前記部分の傾きを修正し、前記基板支持部に提供される修正された周期的電圧関数を形成するイオン電流補償構成要素と、
前記スイッチモード電力供給部および前記イオン電流補償構成要素と通信しているコントローラと
を備え、
前記コントローラは、前記基板支持部に提供された場合、前記基板の表面に到達するイオンの定義されたイオンエネルギー分布関数をもたらすであろう、前記イオン電流補償の値を識別するように構成されている、システム。
（項目３３）
前記コントローラは、前記基板の前記表面に到達するイオンの前記定義されたイオンエネルギー分布関数が達成されるまで、前記イオン電流補償の振幅を調節する、項目３２に記載の装置。
（項目３４）
前記コントローラは、前記基板支持部に提供された場合、前記基板の前記表面に到達するイオンの定義されたイオンエネルギーをもたらすであろう、前記周期的電圧関数の前記パルスの振幅を識別するようにさらに構成されている、項目３２に記載の装置。
（項目３５）
前記コントローラは、前記基板の前記表面に到達するイオンの前記定義されたイオンエネルギーが達成されるまで、前記周期的電圧関数の前記パルスの振幅を調節する、項目３４に記載の装置。
（項目３６）
基板を処理するように構成されているプラズマのイオン電流を監視する方法を行うためのプロセッサ読み取り可能な命令で符号化されている非一過性の有形コンピュータ読み取り可能な記憶媒体であって、前記方法は、
第１の値を有するイオン電流補償を与えられた修正された周期的電圧関数をサンプリングすることと、
第２の値を有するイオン電流補償を与えられた前記修正された周期的電圧関数をサンプリングすることと、
前記第１および第２のサンプリングに基づいて、時間の関数として前記修正された周期的電圧関数の傾きを決定することと、
前記傾きに基づいて、前記基板上の一定の電圧が前記修正された周期的電圧関数の少なくとも１つのサイクルに対して存在するであろう、前記イオン電流補償の第３の値を計算することと
を含む、非一過性の有形コンピュータ読み取り可能な記憶媒体。
（項目３７）
前記プラズマのプラズマシースにわたるシース電圧を計算することをさらに含む、項目３６に記載の非一過性の有形コンピュータ読み取り可能な記憶媒体。 These and other embodiments are described in more detail herein.
For example, the invention of the present application provides the following items.
(Item 1)
A method of establishing one or more plasma sheath voltages,
To provide a modified periodic voltage function to the substrate support of the plasma chamber, the substrate support is coupled to a substrate configured for processing in the plasma and said modified periodic. The target voltage function comprises a periodic voltage function modified by the ion current compensation Ic.
The modified periodic voltage function comprises a pulse and a portion between the pulses.
The pulse is a function of the periodic voltage function.
The slope of the portion between the pulses is a function of the ion current compensation Ic.
At least accessing the _{effective capacity value C 1} representing the capacity of the substrate support and
Would result in a defined ion energy distribution function of the ions reaching the surface of the substrate, the method comprising: identifying the value of said ion current compensation Ic, to the identification, the effective capacitance C ₁ and the A method comprising the function of a _{slope dV 0} / dt of said portion between pulses.
(Item 2)
The method according to item 1, wherein the defined ion energy distribution is a narrow ion energy distribution.
(Item 3)
The method of item 2, wherein the defined ion energy distribution corresponds to a constant voltage on the substrate surface during the portion between the pulses.
(Item 4)
The value of the ion current compensation Ic satisfies the function f as follows.

The method according to item 1.
(Item 5)
Setting the ion current compensation Ic to the first value and
Determining the sign of the function f and
4. The item 4 comprises further including increasing the ion current compensation Ic when the sign of the function f is positive and decreasing the ion current compensation Ic when the sign of the function f is negative. Method.
(Item 6)
The method of item 1, wherein the identification comprises sampling the voltage of the portion between the pulses at two or more times.
(Item 7)
The method of item 6, _{wherein the identification comprises calculating the slope dV 0} / dt from the voltage sampled at the two or more times.
(Item 8)
_{The identification comprises calculating the slope dV 0} / dt for two or more cycles of the modified periodic voltage function, each of the two or more cycles said ion current compensation. 7. The method of item 7, which is associated with a different value of Ic.
(Item 9)
The identification is to sample the voltage of the portion between the pulses during the first cycle and the second cycle, and to calculate the _{slope dV 0 / dt from at least these sampled voltages.} The method according to item 6, including the above.
(Item 10)
The method of item 1, wherein the ion current compensation Ic is _{linearly associated with an ion current I I across the plasma sheath of the plasma.}
(Item 11)
The ion current compensation Ic is linearly related to the _{ion current I I according to the following equation.}

The method of item 10, wherein C ₁ is the effective capacitance of the plasma chamber as seen by the bias supply, and C _stray is the cumulative stray capacitance of the plasma chamber as seen by the bias supply.
(Item 12)
The method according to item 11, wherein the effective capacity C _{1 varies with time.}
(Item 13)
The method according to item 11, wherein the ion current compensation Ic varies with time.
(Item 14)
The method of item 1, further comprising providing the substrate support with the modified periodic voltage function such that the ions reach the surface of the substrate with a first ion energy.
(Item 15)
14. The method of item 14, wherein the modified periodic voltage function has a first voltage step corresponding to the first ion energy.
(Item 16)
15. The method of item 15, further comprising providing the substrate support with the modified periodic voltage function with a second value of the ion current compensation Ic to expand the ion energy distribution function.
(Item 17)
15. The method of item 15, wherein the first voltage step and the second voltage step are provided in adjacent cycles of the modified periodic voltage function.
(Item 18)
The method of item 14, wherein the provision has a negligible effect on the density of the plasma.
(Item 19)
A method of biasing the plasma to achieve defined ion energy on the surface of the substrate in the plasma processing chamber, said method.
Applying a modified periodic voltage function to the substrate support with a modified periodic voltage function by ion current compensation,
Sampling at least one cycle of the modified periodic voltage function to generate a voltage data point,
Estimating the value of the first ion energy on the surface of the substrate from the voltage data point,
A method comprising adjusting the modified periodic voltage function until the first ion energy is equal to the defined ion energy.
(Item 20)
19. The method of item 19, further comprising sampling at least one cycle of the modified periodic voltage function after each voltage increment of the adjustment to calculate the value of the first ion energy.
(Item 21)
19. The method of item 19, wherein the estimation is a function of the ion current as an input. (Item 22)
21. The method of item 21, wherein the ion current is a function of the ion current compensation.
(Item 23)
The following equation is used in estimating the value of the first ion energy,

ΔV is the voltage step, C ₁ is the effective capacity of the chamber as seen by the bias feeder, and C _shear is the sheath capacity of the plasma sheath, depending on the ion current, item 22. The method described.
(Item 24)
23. The method of item 23, wherein the adjustment comprises adjusting the step voltage ΔV of the modified periodic voltage function until the first ion energy is equal to the defined ion energy. ..
(Item 25)
19. The method of item 19, further comprising changing the first value of the ion current compensation to a second value and expanding the width of the ion energy distribution.
(Item 26)
19. The method of item 19, wherein the application and the adjustment have a negligible effect on the plasma density of the plasma.
(Item 27)
19. The method of item 19, wherein the adjustment comprises adjusting the bias feeder voltage until the first ion energy is equal to the defined ion energy. (Item 28)
A method of achieving an ion energy distribution function width, wherein the method is:
To provide a modified periodic voltage function to the substrate support of the plasma processing chamber,
Sampling at least two voltages from the non-sinusoidal waveform in the first and second time,
To calculate the slope of at least two voltages as dV / dt,
Comparing the slope with a reference slope known to correspond to the width of the ion energy distribution function,
A method comprising adjusting the modified periodic voltage function such that the slope approaches the reference slope.
(Item 29)
The first time occurs during the first cycle of the modified periodic voltage function, and the second time occurs during the second cycle of the modified periodic voltage function. Item 28.
(Item 30)
28. The method of item 28, wherein the first and second times occur during the same cycle of the modified periodic voltage function.
(Item 31)
28. The method of item 28, wherein the sampling is performed at a sampling rate of at least 400 kHz.
(Item 32)
With a plasma processing chamber configured to contain plasma,
A substrate support portion located in the plasma processing chamber and arranged to support the substrate during plasma processing.
A power supply unit that provides a periodic voltage function to the substrate support, wherein the periodic voltage function includes a power supply unit having a pulse and a portion between the pulses.
An ion current compensating component that corrects the slope of the portion between the pulses to form a modified periodic voltage function provided to the substrate support.
It comprises a switch mode power supply and a controller communicating with the ion current compensation component.
The controller is configured to identify the value of the ion current compensation that, when provided to the substrate support, would result in a defined ion energy distribution function of the ions reaching the surface of the substrate. There is a system.
(Item 33)
32. The apparatus of item 32, wherein the controller adjusts the amplitude of the ion current compensation until the defined ion energy distribution function of ions reaching the surface of the substrate is achieved.
(Item 34)
The controller is to identify the amplitude of the pulse of the periodic voltage function that, when provided to the substrate support, will provide the defined ion energy of the ions reaching the surface of the substrate. The device according to item 32, which is further configured.
(Item 35)
34. The device of item 34, wherein the controller adjusts the amplitude of the pulse of the periodic voltage function until the defined ion energy of the ions reaching the surface of the substrate is achieved.
(Item 36)
A non-transient tangible computer-readable storage medium encoded by a processor readable instruction for performing a method of monitoring the ion currents of a plasma configured to process a substrate, said. The method is
Sampling a modified periodic voltage function given ion current compensation with a first value,
Sampling the modified periodic voltage function given the ion current compensation with a second value,
Determining the slope of the modified periodic voltage function as a function of time, based on the first and second samplings,
Based on the slope, calculating the third value of the ion current compensation that a constant voltage on the substrate will be present for at least one cycle of the modified periodic voltage function. Non-transient tangible computer readable storage medium, including.
(Item 37)
36. The non-transient tangible computer readable storage medium of item 36, further comprising calculating the sheath voltage across the plasma sheath of the plasma.

The various objects and advantages of the invention as well as a more complete understanding of the invention are carried out when similar or similar elements are considered in conjunction with the accompanying drawings represented by the same reference numerals throughout several drawings. It is obvious and easily understood by reference to the form and the accompanying claims.

FIG. 1 illustrates a block diagram of a plasma processing system according to an implementation of the present invention. FIG. 2 is a block diagram illustrating an exemplary embodiment of the switch mode power system depicted in FIG. FIG. 3 is a schematic representation of the components that can be utilized to implement the switch mode bias supply unit described with reference to FIG. FIG. 4 is a schematic timing diagram depicting two drive signal waveforms. FIG. 5 is a single mode graphical representation of operating a switch mode bias supply unit that results in an ion energy distribution that concentrates on a particular ion energy. FIG. 6 is a graph depicting a bimodal mode of operation in which two distinct peaks in the ion energy distribution are generated. 7A and 7B are graphs depicting actual direct ion energy measurements made in plasma. FIG. 8 is a block diagram illustrating another embodiment of the present invention. FIG. 9A is a graph illustrating an exemplary periodic voltage function modulated by a sinusoidal modulation function. FIG. 9B is an exploded view of a portion of the periodic voltage function depicted in FIG. 9A. FIG. 9C depicts the distribution resulting from ion energy resulting from sinusoidal modulation of a periodic voltage function based on a time average. FIG. 9D depicts an actual direct ion energy measurement made in a plasma with a time average IEDF resulting from the periodic voltage function being modulated by a sinusoidal modulation function. FIG. 10A illustrates that the periodic voltage function is modulated by a sawtooth wave modulation function. FIG. 10B is an exploded view of a portion of the periodic voltage function depicted in FIG. 10A. FIG. 10C is a graph depicting the resulting distribution of ion energy, based on time averages, resulting from sinusoidal modulation of the periodic voltage function in FIGS. 10A and 10B. FIG. 11 is a graph showing the IEDF function in the right column and the modulation function associated with the left column. FIG. 12 is a block diagram illustrating an embodiment in which the ion current compensation component compensates for the ion current in the plasma chamber. FIG. 13 is a schematic diagram illustrating exemplary ion current compensation components. FIG. 14 is a graph illustrating an exemplary voltage at node Vo, depicted in FIG. 15A-15C are voltage waveforms that appear on the surface of a substrate or wafer in response to a compensating current. FIG. 16 is an exemplary embodiment of a current source that can be implemented to implement the current source described with reference to FIG. 17A and 17B are block diagrams illustrating other embodiments of the invention. FIG. 18 is a block diagram illustrating yet another embodiment of the present invention. FIG. 19 is a block diagram illustrating yet another embodiment of the present invention. FIG. 20 is a block diagram input parameter and control output that may be utilized in connection with the embodiments described with reference to FIGS. 1-19. FIG. 21 is a block diagram illustrating yet another embodiment of the present invention. FIG. 22 is a block diagram illustrating yet another embodiment of the present invention. FIG. 23 is a block diagram illustrating yet another embodiment of the present invention. FIG. 24 is a block diagram illustrating yet another embodiment of the present invention. FIG. 25 is a block diagram illustrating yet another embodiment of the present invention. FIG. 26 is a block diagram illustrating yet another embodiment of the present invention. FIG. 27 is a block diagram illustrating yet another embodiment of the present invention. FIG. 28 illustrates a method according to an embodiment of the present disclosure. FIG. 29 illustrates another method according to one embodiment of the present disclosure. FIG. 30 illustrates an embodiment of a method of controlling the ion energy distribution of ions affecting the surface of a substrate. FIG. 31 illustrates a method of setting IEDF and ion energy. FIG. 32 illustrates two modified periodic voltage function waveforms delivered to the substrate support according to one embodiment of the present disclosure. FIG. 33 illustrates an ion current waveform that can show instability of the plasma source or changes in plasma density. FIG. 34 illustrates an _{ion current I I} of a modified periodic voltage function waveform with an aperiodic shape. FIG. 35 illustrates a modified periodic voltage function waveform that can indicate a failure in the bias supply section. FIG. 36 illustrates a modified periodic voltage function waveform that can show dynamic changes in system capacitance. FIG. 37 illustrates a modified periodic voltage function waveform that may indicate changes in plasma density. FIG. 38 illustrates sampling of ion currents for different process executions, where drift of ion currents can indicate system drifts. FIG. 39 illustrates sampling of ion currents for different process parameters. FIG. 40 illustrates two bias waveforms monitored in the chamber without plasma. FIG. 41 illustrates two bias waveforms that can be used to justify the plasma process. FIG. 42 illustrates several power supply voltage and ion energy plots showing the relationship between power supply voltage and ion energy. FIG. 43 illustrates an embodiment of a method of controlling the ion energy distribution of ions affecting the surface of a substrate. FIG. 44 illustrates various waveforms at different points in the systems disclosed herein. FIG. 45 illustrates the effect of producing a final gradual change in the ion current compensation Ic to match the _{ion current I I.} FIG. 46 illustrates the selection of ion energy. FIG. 47 illustrates the selection and expansion of the ion energy distribution function width. Figure 48 is the ion energy level has a narrow IEDF width, illustrates more than one single pattern of the power supply unit voltage V _PS that can be used to achieve the ion energy level. Figure 49 is the ion energy level has a narrow IEDF width illustrates another pattern of the power supply unit voltage V _PS that can be used to achieve more than one ion energy level. Figure 50 illustrates one combination of the defined power supply voltage can be used to generate a IEDF V _PS and the ion current compensation I _C.

An exemplary embodiment of a plasma processing system is generally shown in FIG. As depicted, the plasma power supply unit 102 is coupled to the plasma processing chamber 104, and the switch mode power supply unit 106 is coupled to the support unit 108 in which the substrate 110 is placed in the chamber 104. To. Also shown is a controller 112 coupled to the switch mode power supply unit 106.

In this exemplary embodiment, the plasma processing chamber 104 can be realized by a chamber of substantially conventional construction, including, for example, a vacuum enclosure, which is evacuated by a pump or a plurality of pumps (not shown). .. Also, as will be appreciated by those of skill in the art, the plasma excitation in the chamber 104 can be from any one of a variety of sources, such as, for example, a helicon-type plasma source, where the various sources are in the reactor. Includes a magnetic coil and antenna for igniting and sustaining the plasma 114 at, and a gas inlet may be provided for introducing gas into the chamber 104.

As depicted, the exemplary plasma chamber 104 is arranged to perform plasma-assisted etching of the material utilizing the energy ion impact of the substrate 110 and other plasma treatments (eg, plasma deposition and plasma-assisted ion implantation). And composed. The plasma power supply unit 102 in the present embodiment ignites and sustains the plasma 114 via a matching circuit (not shown) at one or more frequencies (eg, 13.56 MHz) in the chamber 104. Is configured to apply power (eg, RF power) to. The present invention is not limited to any particular type of plasma power supply 102 or source for coupling power to the chamber 104, and various frequencies and power levels are capacitive or inductive to the plasma 114. Please understand that it can be combined with.

As depicted, the dielectric substrate 110 to be processed (eg, a semiconductor wafer) is at least partially supported by a support 108 which may include a portion of a conventional wafer chuck (eg, for semiconductor wafer processing). Will be done. The support 108 has an insulating layer between the support 108 and the substrate 110, which may be formed to be capacitively coupled to the platform but may float at a different voltage than the support 108. ..

As described above, when the substrate 110 and the support 108 are conductors, it is possible to apply an invariant voltage to the support 108, and the voltage applied to the support 108 as a result of electrical conduction through the substrate 110. Is also applied to the surface of the substrate 110.

However, when the substrate 110 is dielectric, the application of an invariant voltage to the support 108 is not effective for applying a voltage over the entire surface of the substrate 110 to be processed. As a result, the exemplary switch mode power supply 106 attracts ions within the plasma 114 to collide with the substrate 110 so as to perform controlled etching and / or vapor deposition and / or other plasma assisted processes on the substrate 110. It is configured to be controlled to bring a possible voltage onto the surface of the substrate 110.

Further, as further discussed herein, embodiments of the switch mode power supply unit 106 include power applied (to the plasma 114) by the plasma power supply unit 102 and to the substrate 110 by the switch mode power supply unit 106. It is configured to operate so that there is very little interaction with the applied power. The power applied by the switch mode power supply unit 106 can be controlled, for example, to allow control of ion energy without substantially affecting the density of the plasma 114.

Moreover, many embodiments of the exemplary switch mode power supply unit 106 depicted in FIG. 1 are realized by relatively inexpensive components that can be controlled by a relatively simple control algorithm. Also, many embodiments of the switch mode power supply unit 106 are much more efficient than the prior art approach. That is, it reduces energy costs and the expensive materials associated with removing excess thermal energy.

One of the known techniques for applying a voltage to a dielectric substrate utilizes a high power linear amplifier with a complex control method for applying power to the substrate support, which induces a voltage on the surface of the substrate. do. However, this technique has not been adopted by commercial entities because it has been found to be inefficient or poorly manageable. In particular, the linear amplifiers utilized are typically large, very expensive, inefficient, and difficult to control. In addition, linear amplifiers essentially require AC coupling (eg, blocking capacitors) and auxiliary functions such as chucking, which are achieved by parallel feeding circuits and parallel feeding. The circuit, along with the chuck, impairs the system's AC spectral purity to the source.

Another technique under consideration is to apply high frequency power to the substrate (eg, by one or more linear amplifiers). However, it is known that this technique adversely affects the plasma density because the high frequency power applied to the substrate affects the plasma density.

In some embodiments, the switch mode power supply unit 106 depicted in FIG. 1 may be implemented by step-down, boost, and / or step-down-boost power technology. In these embodiments, the switch mode power supply unit 106 may be controlled to apply variable levels of pulsed power to elicit a potential on the surface of the substrate 110.

In another embodiment, the switch mode power supply unit 106 is implemented by other more advanced switch mode power and control techniques. Next, referring to FIG. 2, for example, the switch mode power supply unit described with reference to FIG. 1 applies power to the substrate 110 to deliver one or more desired energies of ions colliding with the substrate 110. It is realized by the switch mode bias supply unit 206, which is used to bring about. Also shown are an ion energy control component 220, an arc detection component 222, and a controller 212 coupled to both the switch mode bias supply section 206 and the waveform memory 224.

The illustrated array of these components is logical. Thus, the components can be combined or further separated in a real implementation, and the components can be connected in various ways without changing the basic behavior of the system. In some embodiments, the controller 212, which may be implemented, for example, by hardware, software, firmware, or a combination thereof, can be utilized to control both the power supply unit 202 and the switch mode bias supply unit 206. However, in an alternative embodiment, the power supply unit 202 and the switch mode bias supply unit 206 are realized by a completely separated functional unit. As a further embodiment, the controller 212, waveform memory 224, ion energy control unit 220, and switch mode bias supply unit 206 can be integrated into a single component (eg, reside in a common enclosure) or are separate. Can be distributed among the components.

The switch mode bias supply section 206 in this embodiment generally supplies a voltage to the support section 208 in a controllable manner to provide the desired (or defined) distribution of the energy of the ions colliding with the surface of the substrate. It is configured to apply. More specifically, the switch mode bias supply 206 is intended to provide the desired (or defined) distribution of ion energy by applying one or more specific waveforms to the substrate at a specific power level. It is composed of. More specifically, in response to an input from the ion energy control unit 220, the switch mode bias supply unit 206 provides a specific ion energy by applying a specific power level and is in the waveform memory 224. A specific power level is applied using one or more voltage waveforms defined by the waveform data. As a result, one or more specific ion impact energies may be selected by the ion control portion to perform controlled etching (or other form of plasma processing) of the substrate.

As depicted, switch mode power supply 206 is adapted to switch power to support 208 of board 210 in response to drive signals from the corresponding drive components 228', 228''. Includes switch components 226', 226'' (eg, high power field effect transistors). Further, the drive signals 230 ″ and 230 ″ generated by the drive components 228 ′ and 228 ″ are controlled by the controller 212 based on the timing defined by the contents of the waveform memory 224. For example, the controller 212 in many embodiments is adapted to interpret the contents of the waveform memory and generate drive control signals 232', 232'', where the drive control signals 232', 232'are switching components 226. Used by drive components 228', 228' to control drive signals 230', 230'' to'226''. Two switch components 226', 226'' that can be arranged in a half-bridge configuration are depicted for exemplary purposes, but of course fewer or additional switch components are included in various architectures (eg, eg). It is assumed that it can be implemented in the H-bridge configuration).

In many modes of operation, the controller 212 (eg, using waveform data) modulates the timing of the drive control signals 232', 232'' to provide the desired waveform at the support 208 of the substrate 210. In addition, the switch mode bias supply section 206 is adapted to power the substrate 210 based on the ion energy control signal 234, which can be a DC signal or a time-varying waveform. Accordingly, the present embodiment controls the timing signal to the switching component and controls the power (controlled by the ion energy control component 220) applied by the switching component 226', 226''. , Allows control of ion distribution energy.

In addition, the controller 212 in this embodiment is configured to perform an arc management function in response to an arc in the plasma chamber 204 detected by the arc detection component 222. In some embodiments, when an arc is detected, the controller 212 determines the drive control signal 232', such that the waveform applied at the output 236 of the switch mode bias supply 206 extinguishes the arc in the plasma 214. Change 232''. In another embodiment, the controller 212 simply interrupts the application of the drive control signals 232', 232'' so that the application of power at the output 236 of the switch mode bias supply 206 is interrupted. erase.

Next, with reference to FIG. 3, this is a schematic representation of the components that can be utilized to implement the switch mode bias supply unit 206 described with reference to FIG. As shown, the switching components T1 and T2 in this embodiment are arranged in a half-bridge (also referred to as a totem pole) topology. Collectively, R2, R3, C1, and C2 represent plasma loads, C10 is the effective capacitance (also referred to herein as series or chuck capacitance), and C3 is on the surface of the substrate. Any physical capacitor to prevent DC current from the induced voltage or the voltage of the electrostatic chuck (not shown) from flowing through the circuit. C10 is referred to as the effective capacitance because it contains the series capacitance (also referred to as chuck capacitance) of the substrate support and electrostatic chuck (or E-chuck), as well as other capacitance inherent in the application of bias such as insulation and substrate. Will be done. As depicted, L1 is a stray inductance (eg, the natural inductance of a conductor that powers a load). Also, in this embodiment, there are three inputs: Vbus, V2, and V4.

V2 and V4 represent drive signals (eg, drive signals 230', 230'' output by drive components 228', 228'' described with reference to FIG. 2), in the present embodiment. V2 and V4 can be timed so that the closure of T1 and T2 is modulated and the shape of the voltage output at Vout applied to the substrate support can be controlled (eg, of the pulse). Length and / or mutual delay). In many implementations, the transistor used to implement the switching components T1 and T2 is not an ideal switch, and therefore transistor-specific characteristics are taken into account in order to reach the desired waveform. In many modes of operation, simply changing the timing of V2 and V4 allows the application of the desired waveform in Vout.

For example, switches T1 and T2 may be operated such that the voltage on the surface of the substrates 110, 210 is generally negative and the periodic voltage pulse approaches and / or slightly exceeds the positive voltage reference. The value of the voltage on the surface of the substrates 110, 210 defines the energy of the ion, which can be characterized in terms of the ion energy distribution function (IEDF). To bring the desired voltage on the surface of the substrates 110, 210, the pulse at Vout is generally rectangular so as to attract enough electrons to the surface of the substrates 110, 210 to achieve the desired voltage and corresponding ion energy. And may have a width sufficient to induce a short-term positive voltage on the surface of the substrates 110, 210.

Periodic voltage pulses approaching and / or slightly above the positive voltage reference may have a minimum time limited by the ability of switches T1 and T2 to switch. The generally negative portion of the voltage can be extended unless the voltage builds up to a level that damages the switch. At the same time, the length of the negative part of the voltage should exceed the ion transition time.

Vbus in this embodiment defines the amplitude of the pulse measured at Vout, which defines the voltage on the surface of the substrate, and thus the ionic energy. Again, with a brief reference to FIG. 2, the Vbus can be coupled to an ion energy control section, which is realized by a DC power supply that is adapted to apply a DC signal or time-varying waveform to the Vbus. Can be done.

The pulse width, pulse shape, and / or mutual delay of the two signals V2, V4 are modulated to reach the desired waveform in Vout (also referred to herein as a modified periodic voltage function). The voltage applied to the Vbus can affect the characteristics of the pulse. In other words, the voltage Vbus can affect the pulse width, pulse shape, and / or the relative phase of the signals V2, V4. Referring briefly to FIG. 4, for example, as depicted in FIG. 4, two drive signal waveforms (as V2 and V4) that can be applied to T1 and T2 to generate a periodic voltage function in Vout. A schematic timing diagram to depict is shown. The timing of the two gate drive signals V2, V4 is controlled to modulate the shape of the pulse at Vout (eg, to achieve the minimum time of the pulse but reach the peak value of the pulse at Vout). Can be done.

For example, although the time applied by each pulse at Vout is shorter than the time T between pulses, a positive voltage is induced on the surfaces of the substrates 110 and 210, and electrons are transmitted to the surfaces of the substrates 110 and 210. Two gate drive signals V2, V4 may be applied to the switching components T1, T2 so that they may be long enough to attract. Furthermore, it has been found that the gradient of the voltage applied to the Vout between the pulses can be controlled by changing the gate voltage level between the pulses (eg, between the pulses, substantially on the surface of the substrate. To achieve a constant voltage). In some modes of operation, the iteration rate of the gate pulse is about 400 kHz, which, of course, can vary from application to application.

Although not required, in practice, based on the modeling and refinement of the actual implementation, a waveform that can be used to generate the desired (or defined) ion energy distribution can be defined, and the waveform (eg, for example). , As a series of voltage levels, can be stored (in the waveform memory portion described with reference to FIG. 1). In addition, in many implementations, the waveform can be generated directly (eg, without feedback from Vout). Therefore, it avoids unwanted aspects of the feedback control system (eg, settling time).

Again, referring to FIG. 3, the Vbus can be modulated to control the energy of the ions, while the stored waveform controls the gate drive signals V2, V4 to achieve the desired pulse amplitude at Vout. , Can be used to minimize pulse width. Again, this is done according to the specific characteristics of the transistor that can be modeled or implemented and experimentally established. Referring to FIG. 5, for example, a graph depicting Vbus vs. time, voltage vs. time on the surface of substrates 110, 210, and corresponding ion energy distribution is shown.

The graph of FIG. 5 depicts a single mode in which the switch mode bias feeders 106, 206 operate, resulting in an ion energy distribution focused on a particular ion energy. As depicted, the voltage applied to the Vbus is kept constant to result in a single concentration of ion energy in this embodiment, while the voltage applied to V2 and V4 is shown in FIG. It is controlled to generate a pulse at the output of the switch mode bias feeders 106, 206, which results in a corresponding ion energy distribution (eg, using the drive signal depicted in FIG. 3).

As depicted in FIG. 5, the potentials on the surfaces of the substrates 110, 210 are generally negative and collide with the surfaces of the substrates 110, 210, attracting the ions to be etched. The periodic short pulses applied to the substrates 110, 210 (by applying the pulse to the Vout) have a scale defined by the potential applied to the Vbus, and these pulses are the potentials of the substrates 110, 210. (Eg, near positive or weak positive potential), and short-term changes in potential along the surface of the substrates 110, 210 generally achieve a negative potential on the substrate. Attracts electrons to the surface of the. As depicted in FIG. 5, the constant voltage applied to the Vbus results in a single concentrated ion flux at a particular ion energy. Therefore, a particular ionic impact energy can be selected by simply setting Vbus to a particular potential. In other modes of operation, two or more separate concentrations of ion energy can be generated (see, eg, FIG. 49).

Those skilled in the art will recognize that the power supply unit does not have to be limited to the switch mode power supply unit, and therefore the output of the power supply unit can also be controlled in order to achieve a certain ion energy. Will. Accordingly, the output of the power supply unit, whether otherwise mode and will switch mode, when considered without being combined with an ion current compensation or the ion current, also referred to as a power supply voltage V _PS can.

Next, with reference to FIG. 6, a graph depicting, for example, a bimodal mode of operation in which two separate peaks are generated in the ion energy distribution is shown. As shown, in this mode of operation, the substrate is subject to two different levels of voltage and periodic pulses, resulting in two separate concentrations of ion energy. As depicted, the voltage applied at Vbus alternates between the two levels to result in two different ion energy concentrations, each level defining the energy level of the two ion energy concentrations.

FIG. 6 depicts two voltages on the substrates 110, 210 alternating after each pulse (eg, FIG. 48), but this is not always necessary. In other modes of operation, for example, the voltage applied to V2 and V4 is such that the voltage evoked on the surface of the substrate is second from the first voltage after two or more pulses (eg, FIG. 49). It is switched with respect to the voltage applied to the Vout so as to alternate with the voltage (and vice versa) (eg, using the drive signal depicted in FIG. 3).

In the prior art, a combination of two waveforms (produced by a waveform generator) could be applied to a linear amplifier and a combination of two or more amplified waveforms could be applied to the substrate to provide multiple ion energy. Attempted. However, this approach is much more complex as the approach described with reference to FIG. 6 and therefore requires expensive linear amplifiers and waveform generators.

Next, with reference to FIGS. 7A and 7B, the actual direct ion energy measurements made in the plasma corresponding to the single energy adjustment and the double level adjustment of the DC voltage applied to the Vbus, respectively, are depicted. A graph is shown. As depicted in FIG. 7A, the ion energy distribution concentrates at about 80 eV in response to the constant application of voltage to Vbus (eg, as depicted in FIG. 5). Also, in FIG. 7B, two separate concentrations of ion energy are present at about 85 eV and 115 eV in response to the double level adjustment of Vbus (eg, as depicted in FIG. 6).

Next, with reference to FIG. 8, a block diagram illustrating another embodiment of the invention is shown. As depicted, the switch mode power supply unit 806 is coupled to a substrate support unit 808 via a controller 812, an ion energy control component 820, and an arc detection component 822. The controller 812, the switch mode supply unit 806, and the ion energy control component 820 collectively provide the desired (or defined) ion energy distribution on the surface of the substrate 810 based on a time average. It operates to bring power to the substrate support 808.

For example, a brief reference to FIG. 9A shows a periodic voltage function with a frequency of about 400 kHz, which is modulated by a sinusoidal modulation function of about 5 kHz over multiple cycles of the periodic voltage function. .. FIG. 9B is an exploded view of the portion of the periodic voltage function circled in FIG. 9A, FIG. 9C is the result of time average-based ion energy resulting from sinusoidal modulation of the periodic voltage function. Depict the distribution. Also, FIG. 9D depicts an actual direct ion energy measurement made in plasma of the resulting time average IEDF when the periodic voltage function is modulated by a sinusoidal modulation function. Further, as discussed herein, achieving the desired (or defined) ion energy distribution based on a time average is achieved by simply changing the modulation function applied to the periodic voltage. obtain.

As another example, with reference to FIGS. 10A and 10B, a 400 kHz periodic voltage function is a serrated wave modulation of about 5 kHz to achieve the ion energy distribution depicted in FIG. 10C, based on a time average. Modulated by a function. As depicted, the periodic voltage function used in connection with FIG. 10 is the same as in FIG. 9, but the periodic voltage function in FIG. 10 is a sawtooth wave instead of a sinusoidal function. Modulated by a function.

It should be noted that the ion energy distribution functions depicted in FIGS. 9C and 10C do not represent the instantaneous distribution of ion energy on the surface of the substrate 810, but instead represent the time average of the ion energy. Referring to FIG. 9C, for example, at a particular temporal moment, the ion energy distribution would be a subset of the depicted ion energy distribution that exists over the course of one cycle of the modulation function.

Also, please note that the modulation function does not have to be a fixed function or a fixed frequency. For example, in some cases, one or more cycles of a particular modulation function modulate a periodic voltage function, resulting in a particular time average ion energy distribution, followed by one or more cycles of another modulation function. It may be desirable to modulate the periodic voltage function to result in another time average ion energy distribution. Changes to such a modulation function (modulating a periodic voltage function) can be beneficial in many cases. For example, if a particular ion energy distribution is required to etch a particular geometry or through a particular material, a first modulation function is used, followed by: Different modulation functions can be used to result in different etching geometries or to etch through different materials.

Similarly, the periodic voltage function (eg, the 400 kHz component in FIGS. 9A, 9B, 10A, and 10B, and Vout in FIG. 4) does not need to be strictly fixed (eg, the shape and frequency of the periodic voltage function). However, in general, its frequency is established by the elapsed time of the ions in the chamber such that the ions in the chamber are affected by the voltage applied to the substrate 810.

Referring back to FIG. 8, the controller 812 provides drive control signals 832 ′, 832 ″ to the switch mode supply unit 806 so that the switch mode supply unit 806 generates a periodic voltage function. The switch mode supply unit 806 may be implemented by the components depicted in FIG. 3 (eg, to create the periodic voltage function depicted in FIG. 4), but other switching architectures may be utilized. Of course, it reminds me.

In general, the ion energy control component 820 functions to apply a modulation function to a periodic voltage function (generated by the controller 812 in association with the switch mode power supply unit 806). As shown in FIG. 8, the ion energy control component 820 includes a custom IEDF portion 850, an IEDF function memory 848, a user interface 846, and a modulation controller 840 that communicates with the power component 844. It should be noted that the depiction of these components is in fact intended to convey the functional components that can be brought about by common or separate components.

The modulation controller 840 in this embodiment generally controls the power component 844 (and thus its output 834) based on the data defining the modulation function, and the power component 844 is generated by the switch mode supply unit 806. Generates a modulation function 834 (based on the control signal 842 from the modulation controller 840) applied to the periodic voltage function. The user interface 846 in this embodiment allows the user to select a predetermined IEDF function stored in the IEDF function memory 848, or to define a custom IEDF in connection with the custom IEDF component 850. Is configured to.

In many implementations, the power component 844 is a DC power supply unit that applies a modulation function (eg, variable DC voltage) to the switch mode power supply unit (eg, Vbus of the switch mode power supply unit depicted in FIG. 3). (For example, a DC switch mode power supply unit or a linear amplifier) is included. In these implementations, the modulation controller 840 controls the voltage level output by the power component 844 so that the power component 844 applies a voltage that matches the modulation function.

In some implementations, the IEDF function memory 848 comprises a plurality of datasets corresponding to each of the plurality of IEDF distribution functions, and the user interface 846 allows the user to select the desired (or defined) IEDF function. Allows you to. For example, with reference to FIG. 11, in the right column, exemplary IEDF functions that may be available for user selection are shown. Also, the left column describes the associated modulation function that the modulation controller 840 will apply to the periodic voltage function in connection with the power component 844 to result in the corresponding IEDF function. It should be noted that the IEDF function depicted in FIG. 11 is merely exemplary and other IEDF functions may also be available for selection.

The custom IEDF component 850 generally functions to allow the user to define the desired (or defined) ion energy distribution function via the user interface 846. For example, in some implementations, the custom IEDF component 850 allows the user to establish values for specific parameters that define the distribution of ion energy.

For example, the custom IEDF component 850 relates to relative levels of flux (eg, with respect to the proportion of flux at high levels (IF-high), intermediate levels (IF-mid), and low levels (IF-low)). It may be possible to define an IEDF function in relation to a function that defines an IEDF between energy levels of. In many cases, IF-high, IF-low, and the IEDF function between these levels alone are sufficient to define the IEDF function. As a specific embodiment, the user may request 1200 eV at the 20% contribution level (contribution to the overall IEDF) and 700 eV at the 30% contribution level, along with a sinusoidal IEDF between these two levels.

Also, the custom IEDF portion 850 may allow the user to create a table with a list of one or more (eg, multiple) energy levels and the corresponding percentage contribution of each energy level to the IEDF. Is recalled. Also, in a further alternative embodiment, the custom IEDF component 850, in connection with the user interface 846, presents the user with a graphical tool that allows the user to draw the desired (or defined) IEDF. It is recalled that this allows the user to graphically generate the desired (or defined) IEDF.

In addition, the IEDF function memory 848 and the custom IEDF component 850 also provide a predetermined IEDF such that the user selects a predetermined IEDF function and then produces a custom IEDF function derived from the predetermined IEDF function. It is recalled that they can interact to allow the function to be modified.

Once the IEDF function is defined, the modulation controller 840 provides the data defining the desired (or defined) IEDF function, with the power component 844 providing the modulation function corresponding to the desired (or defined) IEDF. As a result, it is converted into a control signal 842 that controls the power component 844. For example, the control signal 842 controls the power component 844 so that the power component 844 outputs the voltage defined by the modulation function.

Next, with reference to FIG. 12, a block diagram of an embodiment is depicted in which the ion current compensation component 1260 compensates for the ion current in the plasma chamber 1204. Applicants have found that at high energy levels, high levels of ion current in the chamber affect the voltage on the surface of the substrate, and as a result, the ion energy distribution is also affected. For example, a brief reference to FIGS. 15A-15C shows voltage waveforms such as those appearing on the surface of a substrate 1210 or wafer and their relationship to IEDF.

More specifically, FIG. 15A _{depicts a periodic voltage function on the surface of the substrate 1210 when the ion current I I} is equal to the compensating current Ic, and FIG. 15B shows the ion current I _I the compensating current Ic. The voltage waveform on the surface of the substrate 1210 is depicted when it exceeds, and FIG. 15C depicts the voltage waveform on the surface of the substrate when the ion current is less than the compensating current Ic.

The spread of ion energy 1470, depicted in FIG. 15A, when I _I = Ic, is depicted in FIG. 15B, _{the uniform spread of ion energy 1472 when I I} > Ic, or is depicted in FIG. 15C. It is relatively narrow compared to the uniform spread of ion energy 1474 when _{I I <Ic.} Thus, the ion current compensation component 1260 allows narrow spread of ion energy when the ion current is high (eg, by compensating for the effects of the ion current) and also has a width of uniform ion energy spreads 1572, 1574. (For example, if it is desirable to have an ionic energy spread).

As depicted in FIG. 15B, with no ion current compensation (I _I > Ic), the voltage on the surface of the substrate between the positive parts of the periodic voltage function is progressively smaller and less absolute negative. It becomes a value and produces a wider spread of ion energy 1572. Similarly, when ion current compensation is used to raise the level of compensation current to a level above the ion current (I _I <Ic), as depicted in FIG. 15C, the voltage on the surface of the substrate is. In the positive part of the periodic voltage function, it gradually becomes a negative value with a larger absolute value, and a wider spread of uniform ion energy 1574 is produced.

With reference back to FIG. 12, the ion current compensation component 1260 may optionally be implemented as a separate appendage that may be added to the switch mode power supply 1206 and the controller 1212. In other embodiments (eg, as depicted in FIG. 13), the ion current compensation component 1260 refers to the common enclosure 1366 to other components described herein (eg, switch mode power supply). 106, 206, 806, 1206 and ion energy control 220, 820 components). In this embodiment, the periodic voltage function provided to the plasma chamber 1204 comprises a modified periodic voltage function that is modified by ion current compensation from the ion current compensation component 1260. Can be called. The controller 1212 can sample the voltage at different times at the electrical node where the output of the switch mode power supply unit 1206 and the output of the ion current compensation 1260 are combined.

As illustrated in FIG. 13, exemplary ion currents include a current source 1364 coupled to the output 1336 of the switch mode supply and a current controller 1362 coupled to both the current source 1364 and the output 1336. Compensation component 1360 is shown. Further, in FIG. 13, the plasma chamber 1304 is depicted, and in the plasma chamber, there are capacitive elements C ₁ , C ₂ , and an ion current I _I. As depicted, C ₁ may include, but is not limited to, insulation, substrate, substrate support, and intrinsic capacitance of components associated with chamber 1304 (effective capacitance herein). Also referred to as), C ₂ represents sheath capacitance and stray capacitance. In the present embodiment, is provided to the plasma chamber 1304, the periodic voltage function can be measured by V ₀ is provided with the periodic voltage function which is modified by ion current compensation Ic, modified periodic voltage function Can be called.

A sheath (also referred to herein as a plasma sheath) is a layer of plasma near the surface of the substrate, and perhaps the walls of the plasma processing chamber, which provides a high density of positive ions and thus an overall excess positive charge. Accompany. The surface with which the sheath is in contact typically has an overwhelming majority of negative charges. The sheath is generated by electron velocities faster than cations, thus resulting in the majority of the electrons reaching the substrate surface or wall, thus leaving the sheath deprived of electrons. Sheath thickness λ _sheath is a function of plasma characteristics such as plasma density and plasma temperature.

_{In the accessible capacity added to gain control of the process, C 1} in this embodiment is a unique (also referred to as valid) capacity of the component associated with the chamber 1304. Please note that there is no such thing. For example, some prior art approaches utilizing linear amplifiers combine the bias power to the substrate with a blocking capacitor and then utilize the monitoring voltage of the blocking capacitor as feedback to control the linear amplifier. Capacitors may couple switch mode power supplies to substrate supports in many of the embodiments disclosed herein, but feedback control using blocking capacitors is in some embodiments of the invention. It is unnecessary to do so because it is not required.

With reference to FIG. 13, reference is also made to FIG. 14, which is a graph depicting an exemplary voltage (eg, a modified periodic voltage function) in Vo depicted in FIG. In operation, the current controller 1362 monitors the voltage at Vo and the ion current is calculated over the interval t (illustrated in FIG. 14) as follows.

Either or both of the ion current I _I and the intrinsic capacity C ₁ (also referred to as the effective capacity) can change over time. Since C ₁ is essentially a constant for a given tool and is measurable, only Vo needs to be monitored to allow continuous control of the compensation current. As mentioned above, in order to obtain a more monoenergetic distribution of ion energy (eg, as depicted in FIG. 15A), the current controller has an Ic that is substantially identical (or is) to _II. In the alternative, the current source 1364 is controlled as related to equation 2). Thus, the narrow spread of ion energy can be maintained even when the ion current reaches a level that affects the voltage on the surface of the substrate. In addition, if desired, the spread of ion energy can be controlled as depicted in FIGS. 15B and 15C so that additional ion energy is realized on the surface of the substrate.

Also, FIG. 13 depicts a feedback line 1370 that can be used in connection with the control of the ion energy distribution. For example, the value of ΔV depicted in FIG. 14 (also referred to herein as a voltage step or third portion 1406) indicates instantaneous ion energy and is part of many embodiments of a feedback control loop. Can be used in. In one embodiment, the voltage step ΔV is related to ion energy according to equation 4. In other embodiments, the peak voltage V _PP can be related to instantaneous ion energy. Alternatively, the difference between the peak voltage V _{PP and the product of the slope dV 0} / dt of the fourth portion 1408 and the time t can be associated with the instantaneous ion energy (eg V _PP −. dV ₀ / dt · t).

Next, with reference to FIG. 16, exemplary embodiments of the current source 1664 that can be implemented to implement the current source 1364 are shown, as described with reference to FIG. In this embodiment, the controllable negative DC voltage source functions as a current source in connection with the series inductor L2, but those skilled in the art will appreciate that the current source is another component and / or in the light of the present specification. You will understand that it can be achieved by configuration.

FIG. 43 illustrates an embodiment of a method of controlling the ion energy distribution of ions affecting the surface of a substrate. Method 4300 begins by applying the modified periodic voltage function 4302 (see modified periodic voltage function 4402 in FIG. 44) to a substrate support that supports the substrate in the plasma processing chamber. Modified periodic voltage function, ion current compensation _{I C} (see _I C 4404 of FIG. 44) and the power supply unit voltage _{V PS} (see power supply voltage 4406 in FIG. 44) or the like of at least two of the "knobs" Can be controlled through. An exemplary component for generating a power supply unit voltage is the switch mode power supply unit 106 of FIG. To help illustrate the power supply voltage _VPS , this is illustrated herein as if measured without coupling to ionic current and ionic current compensation. Then, the periodic voltage function which is corrected is sampled in the first and second values of the ion current compensation I _C 4304. At least two samples of the modified periodic voltage function of the voltage is obtained for each value of the ion current compensation I _C. Sampling 4304 is performed to allow calculation 4306 (or determination) of _{ion current I I} and sheath capacitance C _{shear 4306.} Such a determination will produce a narrow (eg, minimal) ion energy distribution function (IEDF) width when applied to the substrate support (or applied to the substrate support), ion current compensation. It may involve finding the I _C. Calculation 4306 also optionally determines the voltage step ΔV (also known as the third part of the modified periodic voltage function 1406) based on the waveform sampling 4304 of the modified periodic voltage function. Can also include doing. The voltage step ΔV can be related to the ion energy of the ions reaching the surface of the substrate. When first finding the ion current I _I , the voltage step ΔV can be ignored. Details of sampling 4304 and calculation 4306 are provided in the discussion of FIG. 30 below.

When once the ion current _{I I} and sheath capacitance _{C sheath} is grasped, the method 4300 sets the ion energy and IEDF shape (e.g., width), involves monitoring may move to the method 3100 of FIG. 31 .. For example, FIG. 46 illustrates how a change in power supply voltage can result in a change in ion energy. In particular, the scale of the illustrated power supply voltage is reduced, resulting in a reduction in the scale of ion energy. In addition, FIG. 47, considering the narrow IEDF4714, illustrates that can enlarge the IEDF by adjusting the ionic current compensation _{I C.} Alternatively or in parallel, Method 4300 is described with reference to FIGS. 32-41, utilizing other aspects _{of the ion current I I} , sheath capacitance C _{shear, and modified periodic voltage function waveforms.} As such, various measurement methods can be performed.

In addition to setting the ion energy and / or IEDF width, method 4300 may adjust the modified periodic voltage function 4308 to maintain the ion energy and IEDF width. In particular, the regulation of regulation and power supply voltage of the ion current compensation I _C provided by the ion current compensation components may be performed 4308. In some embodiments, the power supply unit voltage, bus voltage V _bus of the power supply unit _(e.g., bus voltage V _bus of FIG. ₃₎ can be controlled by. Ion current compensation I _C controls the IEDF width, the power supply unit voltage controls the ion energy.

After these adjustments 4308, the modified periodic voltage function can be resampled 4304, the ion current I _I , the sheath capacitance C _shear , and the voltage step ΔV can be calculated again 4306. If (or in alternative desired value) the ion current I _I or the voltage step ΔV values defined other than, 4308 capable of modulating the ion current compensation I _C and / or the power supply unit voltage. A loop of sampling 4304, calculation 4306, and regulation 4308 can occur to maintain the ion energy eV and / or IEDF width.

FIG. 30 illustrates another embodiment of a method of controlling the ion energy distribution of ions affecting the surface of a substrate. In some embodiments, it may be desirable to achieve a narrow width at half maximum (eg, a minimum full width at half maximum or about 6% full width at half maximum in an alternative), as discussed above. Accordingly, Method 3000 can provide a modified periodic voltage function to the chamber and substrate support such that a constant substrate voltage, and thus the sheath voltage, is present on the surface of the substrate. This, in turn, accelerates the ions across the sheath at a substantially constant voltage, thus allowing the ions to affect the substrate with substantially the same ion energy, which in turn provides a narrow IEDF width. For example, in Figure 45, it is possible to adjust the ionic current compensation I _C, constant or substantially to have a constant voltage to the substrate voltage V _sub between pulses, thus, it can be seen that it is possible to narrow the IEDF.

Such modified periodic voltage function, any stray capacitance without assuming the ion current compensation I _C is achieved when equal to the ion current I _I of (periodic voltage function of FIG. 45 (V ₀₎ See the last 5 cycles). Alternatively stray capacitance _{C stray} is considered, the ion current compensation _{I C} is according to Equation 2 are related to the ion current _{I I.}

In the formula, C ₁ is an effective capacity (eg, the intrinsic capacity described with reference to FIGS. 3 and 13). The effective capacity C ₁ can be time-varying or constant. For purposes of this disclosure, narrow IEDF width, when a I I ₌ I _C, or in the alternative, may be present either when the equation 2 is satisfied. Figure 45-50, _{specifically,} is to use I I = _{I C,} these equations are only simplified equation 2, therefore, Equation 2 is used in FIG. 45-50 Please understand that it can be an alternative to equations. _Stray capacitance C stray is the cumulative capacitance of the plasma chamber as seen by the power supply unit. There are eight cycles illustrated in FIG. 45.

Method 3000 is a modified periodic voltage function to the substrate support 3002 (eg, the substrate support 108 of FIG. 1) (eg, the modified periodic voltage function depicted in FIG. 14 or the modification of FIG. 44). It can start with the application of the periodic voltage function 4402). The voltage of the modified periodic voltage function can be sampled more than once 3004, from which the slope dV ₀ / dt can be calculated for at least a portion of the modified periodic voltage function cycle 3006 ( For example, the slope of a portion or fourth portion 1408 between pulses). Decision 3010 at some point prior to the effective capacitance C _{1 (e.g.,} the intrinsic capacitance C10 of the intrinsic capacitance C ₁ and 3 in FIG. 13) to the previously determined value (e.g., from memory or from user input) Access Can be 3008. Slope _dV 0 / dt, based on the effective capacity _{C 1,} and the ion current compensation _{I C,} the function f (equation 3) is, as follows, can be evaluated for each value of the ion current compensation _{I C.}

If the function f is true, the ion current compensation _{I C} is equal to the ion current _{I I,} or in the alternative, Equation 2 truly, 3010 narrow IEDF width is achieved (e.g., see FIG. 45). If the function f is not true, until the function f is true, it is possible to further adjust the ionic current compensation I _C 3012. Another way of looking at this, until matching the ion current I _I (or, in alternative to satisfy the relationship of Equation 2) can modulate ion current compensation I _C, narrow IEDF width is present at that time Will. Such adjustments to the ion current compensation Ic and the resulting narrowing of the IEDF can be seen in FIG. The ion current I _I and the corresponding ion current compensation Ic can be stored in the storage operation 3014 (eg, in memory). Ion current _{I C,} similar to the effective capacitance _{C 1,} may vary time.

When the equation 3 is satisfied, (because I C ₌ I _I, or equation 2 is either in for true) ion current I _I is grasped. Therefore, Method 3000 allows remote and non-invasive measurements _{of ion currents I I in} real time without affecting the plasma. This leads to some new metrics, such as those that will be described with reference to FIGS. 32-41 (eg, remote monitoring of plasma density and remote failure detection of plasma sources).

3012, the ion energy while adjusting the compensation current I _C is likely to be wider than the delta function, ion energy will be similar to that of any of Figures 15B, 15C, or 44,. However, once the compensation current _{I C} that satisfies the equation 2 is found, IEDF is, as illustrated in the right portion of FIG. 15A or FIG. 45, narrowing IEDF width (e.g., minimum IEDF width) emerge as having There will be. This, I C ₌ (or alternatively, when equation 2 is true) when it is I _I, a voltage between pulses of the periodic voltage function which is corrected, a substantially constant sheath or substrate voltage Therefore, to cause ion energy. In FIG. 46, the substrate voltage 4608 includes pulses between constant voltage portions. Since these pulses have a very short duration, their effect on ion energy and IEDF is negligible and therefore the substrate voltage 4608 is referred to as being substantially constant.

The following provides further details for each of the method steps illustrated in FIG. In one embodiment, the modified periodic voltage function can have a waveform as illustrated in FIG. 14, a first portion (eg, first portion 1402), a second portion (eg, eg). 1,404), a third portion (eg, third portion 1406), and a fourth portion (eg, fourth portion 1408), the third portion having a voltage step ΔV. And the fourth portion can have a slope dV ₀ / dt. The slope dV ₀ / dt can be positive, negative, or zero. The modified periodic voltage function 1400 also has a pulse comprising a first portion 1402, a second portion 1404, and a third portion 1406, and a portion between the pulses (fourth portion 1408). It can be expressed as a thing.

The modified periodic voltage function _{can be measured as V 0} in FIG. 3 and can appear as the modified periodic voltage function 4402 in FIG. The modified periodic voltage function 4402 is generated by combining the power supply voltage 4406 (known as the periodic voltage function) with the ion current compensation 4404. The power supply voltage 4406 is mostly involved in generating and shaping the pulse of the modified periodic voltage function 4402, and the ion current compensation 4404 is mostly involved in straight tilting in most cases. It is involved in generating and shaping the part between the pulses, which is the voltage. Increasing the ion current compensation Ic causes a reduction in the magnitude of the slope of the portion between the pulses, as seen in FIG. Reducing the scale of the power supply voltage 4606 causes a reduction in the magnitude of the pulse and peak voltage amplitudes of the modified periodic voltage function 4602, as seen in FIG.

When the power supply unit is a switch mode power supply unit, switching of the first switch T1 and the second switch T2 FIG. 4410 can be applied. For example, the first switch T1 can be mounted as the switch T1 in FIG. 3, and the second switch T2 can be mounted as the second switch T2 in FIG. The two switches are shown as having the same switching time but 180 ° out of phase. In other embodiments, the switch may have a slight phase offset, such as that illustrated in FIG. When the first switch T1 is on, the power supply unit voltage is drawn to the maximum scale, which is the negative value in FIG. 44, because the power supply unit has a negative bus voltage. The second switch T2 is turned off during this period so that the power supply voltage 4406 is isolated from ground. When the switch reverses, the power supply voltage 4406 approaches ground and passes slightly. In the illustrated embodiment, there are two pulse widths, but this is not required. In other embodiments, the pulse width can be the same for all cycles. In other embodiments, the pulse width can vary or be modulated over time.

The modified periodic voltage function is applied to the board support 3002, and the modified periodic voltage function is last before reaching the board support (eg, between the switch mode power supply and the effective capacitance). 3004 which can be sampled as _{V 0} at the accessible point of. The unmodified periodic voltage function (or the power supply unit voltage of FIG. 44) can be supplied from a power supply unit such as the switch mode power supply unit 1206 of FIG. The ion current compensation 4404 of FIG. 44 can be supplied from a current source such as the ion current compensation component 1260 of FIG. 12 or 1360 of FIG.

3004, which can sample part or all of the modified periodic voltage function. For example, a fourth portion (eg, fourth portion 1408) can be sampled. Sampling 3004 can be performed between the power supply unit and the substrate support unit. For example, in FIG. 1, sampling 3004 can be performed between the switch mode power supply unit 106 and the support unit 108. In FIG. 3, sampling 3004 can be performed between the inductor L1 and the intrinsic capacitance C10. In one embodiment, the sampling 3004 may be performed by _{V 0} which between the capacitor C3 and the intrinsic capacitance C10. The sampling 3004 is typically rowed to the left of the intrinsic capacity C10 in FIG. 3 because the intrinsic capacitance C10 and the elements representing the plasma (R2, R3, C1, and C2) are not accessible for real-time measurements. Will be. The intrinsic capacity C10 is typically not measured during processing, but is typically a known constant and can therefore be set during manufacturing. At the same time, in some cases, the intrinsic capacity C10 may fluctuate over time.

Some embodiments require only two samples of the modified periodic voltage function, while others have modified periods of hundreds, thousands, or tens of thousands of samples. It can be obtained for each cycle of the target voltage function. For example, the sampling rate can be greater than 400 kHz. These sampling rates allow for more accurate and detailed monitoring of the modified periodic voltage function and its shape. Similarly, more detailed monitoring of the periodic voltage function allows for more accurate comparison of waveforms between cycles, between different process conditions, between different processes, between different chambers, between different sources, etc. For example, these sampling rates can distinguish the first, second, third, and fourth portions 1402, 1404, 1406, 1408 of the periodic voltage function illustrated in FIG. It may not be possible with conventional sampling rates. In some embodiments, higher sampling rates allow for the resolution of _{voltage step ΔV and slope dV 0 / dt, which is not possible with prior art.} In some embodiments, some of the modified periodic voltage functions can be sampled, while others are not.

Calculation of slope dV ₀ / dt 3006 can be based on a plurality of V ₀ measurements obtained during time t (eg, fourth portion 1408). For example, a linear fit can be made to fit the line to the V _{0 value, and the slope of the line yields a slope dV o} / dt. _{In another case, the V 0} values at the beginning and end of time t (eg, 4th part 1408) in FIG. 14 can be elucidated and these are obtained using the slope of the line obtained as _{dV o / dt.} A line can be fitted between the two points. These are just two of the many methods that can calculate _{the slope dV o} / dt of the part between the pulses.

Determination 3010 may be part of an iterative loop used to adjust the IEDF to a narrow width (eg, minimum width, or, in the alternative, 6% full width at half maximum). Equation 3 applies only if the ion current compensation Ic is _{equal to the ion current I I} (or, in the alternative, is _{related to the I I} according to Equation 2), which is a constant substrate voltage and thus a constant and substantially singular. It occurs only when there is an ion energy (narrow IEDF width) of. A constant substrate voltage of 4608 (V _sub ) can be seen in FIG. Therefore, either the ion current I _I or the ion current compensation Ic can be used in Equation 3 as an alternative.

Alternatively, two values along the fourth part 1408 (also referred to as the part between the pulses) can be sampled for the first and second cycles, the first and second, respectively. The slope can be determined for each cycle. From these two slopes, the ion current compensation Ic that is expected to make Equation 3 true for the third unmeasured slope can be determined. _{Therefore, the ion current I I,} which is predicted to correspond to the narrow IEDF width, can be estimated. These are only two of the many methods that can determine the narrow IEDF width, and the corresponding ion current compensation Ic and / or the corresponding ion current I _I can be found.

The adjustment 3012 to the ion current compensation Ic can be accompanied by either an increase or a decrease in the ion current compensation Ic, and there is no limit to the step size for each adjustment. In some embodiments, the sign of the function f in Equation 3 can be used to determine whether to increase or decrease the ion current compensation. If the sign is negative, the ion current compensation Ic can be reduced, while the positive sign can indicate the need to increase the ion current compensation Ic.

Once an ion current compensating Ic equal to (or, in the alternative, associated with it according to Equation 2) ion current I _{I is identified, Method 3000 further setpoint operation (see Figure 31) or remote chamber and source monitoring operation.} You can move forward (see FIGS. 32-34). Further setpoint operations can include setting the ion energy (see also FIG. 46) and the distribution of the ion energy or the IEDF width (see also FIG. 47). Source and chamber monitoring can include monitoring plasma density, source supply anomalies, plasma arc discharges, and more.

Further, the method 3000 can optionally return to sampling 3004 to continuously (or periodically as an alternative) update the ion current compensation Ic. For example, sampling 3004, calculation 3006, determination 3010, and adjustment 3012 can be performed periodically in consideration of the current ion current compensation Ic to ensure that equation 3 continues to be satisfied. At the same time, if the ion current compensation Ic satisfying equation 3 is updated, the ion current I _I can also be updated and the updated value can be stored 3014.

Method 3000 can _{find and set the ion current compensation Ic to be equal to the ion current I I} or, in the alternative, satisfy equation 2, but is required to achieve a narrow IEDF width. the value of the ion current compensation Ic is (before that in or alternative) without setting the ion current I _C to that value can be determined. For example, the first ion current compensation Ic _{1 is applied for the first cycle, the first slope dV 01} / dt of the voltage between pulses is measured, and the second ion current compensation Ic is applied for the second cycle. _{By applying 2 and measuring the second slope dV 02} / dt of the voltage between the pulses, the third ion current compensation Ic ₃ associated with the third ion current compensation Ic 3 where equation 3 is expected to be true. The slope dV ₀₃ / dt can be determined. The third ion current compensation Ic ₃ may result in a narrow IEDF width when applied. Therefore, only a single adjustment of ion current compensation can be used to satisfy equation 3 and thus determine the ion current compensation Ic corresponding to the ion current _{I I.} Then, the method 3000, the ion current I _C, without even be set to a value that is required to achieve a narrow IEDF width, be moved to the method described in FIGS. 31 and / or Figure 32-41 Can be done. Such embodiments can be performed to increase the rate of regulation.

FIG. 31 illustrates a method of setting the IEDF width and ion energy. The method originates from Method 3000, illustrated in FIG. 30, with left Path 3100 (also referred to as IEDF branch) or right Path 3101 (ion energy branch, respectively) with settings for IEDF width and ion energy. Also called), either one can be taken. The ion energy eV is proportional to the voltage step ΔV or the third portion 1406 of the modified periodic voltage function 1400 of FIG. The relationship between the ion energy eV and the voltage step ΔV can be expressed as Equation 4.

In the formula, C ₁ is an effective capacitance (eg, chuck capacitance, intrinsic capacitance C10 in FIG. 3, or intrinsic capacitance C1 in FIG. 13), and C ₂ is a sheath capacitance (eg, sheath capacitance C4 in FIG. 3, or It is a sheath capacity C2) of FIG. The sheath capacitance C ₂ may include stray capacitance and depends on the _{ion current I I.} The voltage step ΔV can be measured as the change in voltage between the second portion 1404 and the fourth portion 1408 of the modified periodic voltage function 1400. The ion energy eV can be controlled and grasped by controlling and monitoring the voltage step ΔV (a function of the power supply unit voltage or the bus voltage _{such as the bus voltage Vbus in FIG. 3).}

At the same time, the IEDF width can be estimated according to Equation 5.

In the formula, I is I _{I if C is C series} , and I _C if C is C _effective . Time t is the time between pulses, _VPP is the peak voltage, and ΔV is the voltage step.

In addition, the sheath capacitance C ₂ can be used in various computational and monitoring operations. For example, the device _sheath distance λ shear can be estimated as follows.

In the equation, ε is the vacuum permittivity and A is the area of the substrate (or, in the alternative, the surface area of the substrate support). For some high voltage applications, Equation 6 is represented as Equation 7.

In addition, the electric field in the sheath can be estimated as a function of _{the sheath capacitance C 2} , the sheath distance λ _{shear, and the ion energy eV.} Sheath capacitance C _2, along with the ion current I _I, from Equation 8 (alone saturation current I _sat against ionized plasma is linearly is related to the compensation current I _C in), to determine the plasma density n _e Can also be used for.

The sheath capacitance C ₂ and the saturation current I _sat can be used to calculate the effective mass of ions on the substrate surface. The plasma density n _e, the electric field in the sheath, the ion energy eV, the effective mass of the ions, and DC voltage V _DC of the substrate is typically in the art only through indirect means is monitored, the basic Plasma parameter. The present disclosure allows direct measurement of these parameters and thus allows for more accurate monitoring of plasma characteristics in real time.

As seen in Equation 4, the sheath capacitance C ₂ can also be used to monitor and control the ion energy eV, as illustrated in the ion energy branch 3101 of FIG. The ion energy branch 3101 is initiated by receiving a user selection of ion energy 3102. The ion energy branch 3101 can then set the initial power supply unit voltage for the switch mode power supply unit that supplies the periodic voltage function 3104. At some point before the periodic voltage sampling operation 3108, the ion current can also be accessed (eg, accessed from memory) 3106. The periodic voltage can be sampled 3108, and the measured value of the third part of the modified periodic voltage function can be measured 3110. The ion energy I _I can be calculated from the voltage step ΔV of the modified periodic voltage function (also referred to as the third part (eg, the third part 1406)) 3112. The ion energy branch 3101 can then determine if the ion energy is equal to the defined ion energy 3114, if so, the ion energy is at the desired set point and the ion energy branch 3101 ends. can do. If the ion energy is not equal to the defined ion energy, the ion energy branch 3101 can adjust the power supply voltage to 3116 and again sample the periodic voltage 3108. The ion energy branch 3101 can then cycle through sampling 3108, measurement 3110, calculation 3112, determination 3114, and setting 3116 until the ion energy equals the defined ion energy.

A method of monitoring and controlling the IEDF width is illustrated in the IEDF branch 3100 of FIG. The IEDF branch 3100 includes receiving a user selection of the IEDF width 3150 and sampling the current IEDF width 3152. Determination 3154 then determines if the defined IEDF width is equal to the current IEDF width, and if determination 3152 is satisfied, the IEDF width is as desired (or defined) and the IEDF branch 3100 Can be finished. However, if the current IEDF width is not equal to the defined IEDF width, the ion current compensation Ic can be adjusted 3156. This determination 3154 and regulation 3156 can be continued in a circular fashion until the current IEDF width is equal to the defined IEDF width.

In some embodiments, the IEDF branch 3100 can also be implemented to ensure the desired IEDF shape. Various IEDF shapes can be generated, each of which can be associated with different ion energies and IEDF widths. For example, the first IEDF shape can be a delta function, while the second IEDF shape can be a square function. Other IEDF shapes can be cup-shaped. Examples of various IEDF shapes can be seen in FIG.

Using the knowledge of the ion current I _I and the voltage step ΔV, equation 4 can be solved for the ion energy eV. The voltage step ΔV can be controlled by changing the power supply unit voltage, and changing the power supply unit voltage changes the voltage step ΔV. A larger power supply voltage causes an increase in the voltage step ΔV, and a decrease in the power supply voltage causes a decrease in the voltage step ΔV. In other words, by increasing the voltage of the power supply unit, a larger ion energy eV is brought about.

Moreover, because the systems and methods described above operate on continuously changing feedback loops, the desired (or defined) despite changes in plasma due to fluctuations or deliberate adjustments to the plasma source or chamber conditions. Ion energy and IEDF width can be maintained.

Although FIGS. 30-41 are described for a single ion energy, those skilled in the art will generate and monitor the desired (or defined) IEDF width (or IEDF shape) and ion energy. The method will further recognize that it can be used to produce and monitor two or more ion energies, each with its own IEDF width (or IEDF shape). _{For example, the substrate by providing the first power supply voltage VPS} in the first, third, and fifth cycles and the second power supply voltage in the second, fourth, and sixth cycles. Two different narrow ion energies can be achieved for the ions reaching the surface of the (eg, FIG. 42A). The use of three different power supply voltages results in three different ion energies (eg, FIG. 42B). Ion fluxes of different ion energies can be controlled by varying the time each of the plurality of power supply voltages is applied or the number of cycles in which each power supply voltage level is applied (eg, Figure. 42C).

The above discussion constructs an ion current compensation configuration for the periodic voltage function provided by the power supply to control the ion energy of the ions reaching the surface of the substrate during plasma processing and the IEDF width and / or IEDF shape. It shows how it can be used in combination with the ion current compensation provided by the element.

Some of the controls described so far are (1) a fixed waveform (the continuous cycle of the waveform is identical), (2) at least two parts proportional to ion energy and IEDF (eg, illustrated in FIG. 14). Use some combination of waveforms with third and fourth portions 1406 and 1408), and (3) high sampling rates (eg, 125 MHz) that allow accurate monitoring of different features of the waveform. Is made possible by. For example, when a prior art such as a linear amplifier sends a waveform similar to a modified periodic voltage function to the substrate, the undesired variation between cycles is to characterize the ion energy or IEDF width (or IEDF shape). , Making it difficult to use these prior art waveforms.

When a linear amplifier is used to bias the substrate support, the waveform is inconsistent from cycle to cycle, so waveform characteristics (eg, slope between pulses) are typically useful. The need for high percentage sampling is not recognized as it will not provide any information. Such useful information, as seen in this and related disclosures, does not occur when fixed waveforms are used.

The fixed waveforms and high sampling rates disclosed herein also allow for more accurate statistical observations. This increased accuracy allows the operation and processing characteristics of the plasma in the plasma source and chamber to be monitored through monitoring the various characteristics of the modified periodic voltage function. For example, a modified periodic voltage function measurement allows remote monitoring of sheath capacitance and ion current and can be monitored without knowledge of the chamber process or other chamber details. Some embodiments are followed by only a few of the numerous methods in which the systems and methods described so far can be used for non-invasive monitoring and failure detection of sources and chambers. Illustrate.

As an example of monitoring, with reference to FIG. 14, the DC offset of waveform 1400 can represent the integrity of the plasma source (hereinafter referred to as "source"). In another embodiment, the slope of the top 1404 (second part) of the pulse of the modified periodic voltage function can be related to the damping effect in the source. The standard deviation of the slope of the top portion 1404 from the horizontal (illustrated as having a slope equal to 0) is another way to monitor the integrity of the source based on some aspect of the waveform 1400. Another aspect is along a fourth portion 1408 of the periodic voltage function that has been modified to measure the standard deviation of V ₀ points sampled involves associating the chamber resonance standard deviation. For example, if this standard deviation is monitored between continuous pulses and the standard deviation increases over time, this may indicate that there is resonance in the chamber, eg, in the electrostatic chuck. Resonance can be a sign of poor electrical connection to or within the chamber, or additional unwanted inductance or capacitance.

FIG. 32 illustrates two modified periodic voltage function waveforms delivered to the substrate support according to one embodiment of the present disclosure. When compared, the two modified periodic voltage functions can be used for chamber matching, or in-situ anomaly or fault detection. For example, one of the two modified periodic voltage functions can be the reference waveform and the second function can be obtained from the plasma processing chamber during calibration. The difference between the two modified periodic voltage functions (eg, the difference in peak voltage _VPP ) can be used to calibrate the plasma processing chamber. Alternatively, a second modified periodic voltage function can be compared to the reference waveform during processing, and any difference in waveform characteristics (eg, shift) can indicate a failure (eg, shift). The difference in the slope of the fourth part 3202 of the modified periodic voltage function).

FIG. 33 illustrates an ion current waveform that can show instability of the plasma source or changes in plasma density. _{Fluctuations in the ion currents I I} , such as those illustrated in FIG. 33, can be analyzed to identify failures and anomalies in the system. For example, the periodic variation in FIG. 33 may indicate low frequency instability in the plasma source (eg, plasma power supply unit 102). Such fluctuations in the ion current I _I can also indicate periodic changes in plasma density. This indicator and the possible failures or anomalies it may indicate are only one of many methods in which remote monitoring _{of the ion current I I can be used in particular advantage.}

FIG. 34 illustrates an _{ion current I I} of a modified periodic voltage function waveform with an aperiodic shape. This embodiment of the ion current I _I can show aperiodic fluctuations such as instability of the plasma source or changes in plasma density. Such fluctuations can also indicate various plasma instability such as arc discharge, formation of parasitic plasma, or drift of plasma density.

FIG. 35 illustrates a modified periodic voltage function waveform that can indicate a failure in the bias supply section. The top portion (also referred to as the second portion) of the third illustrated cycle exhibits anomalous behavior that may exhibit resonance within the bias supply section (eg, power supply section 1206 in FIG. 12). This resonance can be an indication of failure in the bias supply. Further analysis of resonance can identify properties that help identify failures in power systems.

FIG. 36 illustrates a modified periodic voltage function waveform that can show dynamic (or non-linear) changes in system capacitance. For example, stray capacitance that is non-linearly dependent on voltage can result in such a modified periodic voltage function. In another embodiment, plasma breakdown or failure at the chuck can also result in such a modified periodic voltage function. In each of the three illustrated cycles, the non-linearity in the fourth part 3602 of each cycle can indicate a dynamic change in system capacitance. For example, the non-linearity can indicate a change in sheath capacity because the other components of the system capacity are largely fixed.

FIG. 37 illustrates a modified periodic voltage function waveform that may indicate changes in plasma density. The modified periodic voltage function illustrated shows a monotonous shift of _{slope dV 0 / dt that can indicate changes in plasma density.} These monotonous shifts can provide direct indication of predictive events such as process etching endpoints. In other embodiments, these monotonous shifts can indicate a process failure in the absence of any predictive events.

FIG. 38 illustrates sampling of ion currents for different process runs, where ion current drifts can indicate system drifts. Each data point can represent an ionic current for a given run, and the permissible limit is a user-defined or automatic limit that defines the permissible ionic current. Drift of ion current, which gradually pushes the ion current above the permissible limit, may indicate that substrate damage may occur. This type of monitoring can also be combined with any number of other conventional monitors such as optical emission thickness measurements. In addition to monitoring ion current drift, these traditional types of monitors can enhance existing monitoring and statistical control.

FIG. 39 illustrates sampling of ion currents for different process parameters. In this illustration, the ion current can be used as a figure of merit to distinguish between different processes and different process characteristics. Such data can be used in the development of plasma recipes and processes. For example, 11 process conditions that result in 11 illustrated ion current data points can be tested and the process that yields the preferred ion current is selected as the ideal process or, in the alternative, the preferred process. be able to. For example, the lowest ion current may be selected as the ideal process, and then the ion current associated with the preferred process is used as a metric to determine if the process is running under preferred process conditions. Can be done. This figure of merit can be used in addition to, or as an alternative to, similar conventional metrics characteristics such as percentage, selectivity, and profile angle, to name a few non-limiting examples.

FIG. 40 illustrates two modified periodic voltage functions monitored without plasma in the chamber. These two modified periodic voltage constraints can be compared and used to characterize the plasma chamber. In embodiments, the first modified periodic voltage function can be the reference waveform, while the second modified periodic voltage function can be the currently monitored waveform. These waveforms can be obtained without plasma in the processing chamber, eg, after chamber cleaning or preventive maintenance, so a second waveform can be used to release the chamber to (or back to) production. Prior to that, it can be used to provide verification of the electrical condition of the chamber.

FIG. 41 illustrates two modified periodic voltage functions that can be used to justify the plasma process. The first modified periodic voltage function can be the reference waveform, while the second modified periodic voltage function can be the currently monitored waveform. The waveform currently being monitored can be compared to the reference waveform, and any difference may indicate a parasitic and / or non-parasitic impedance problem that is otherwise undetectable using conventional monitoring methods. .. For example, the resonance seen on the waveform of FIG. 35 can be detected, which can represent the resonance in the power supply section.

Monitoring any of the metrics illustrated in FIGS. 32-41 while the method 3000 is circulating to update the ion current compensation Ic, the ion current I _I , and / or the sheath capacitance C _shear. Can be done. For example, after each ion current I _I sample is obtained in FIG. 38, method 3000 can return to sampling 3004 to determine the _{updated ion current I I. In another embodiment, correction of ion current I I} , ion energy eV, or IEDF width may be desired as a result of the monitoring operation. Corresponding corrections can be made and method 3000 can return to sampling 3004 to find a new ion current compensation Ic that satisfies equation 3.

Any person skilled in the art will appreciate that the method illustrated in FIGS. 30, 31, and 43 does not require any particular or described order of operation, or is illustrated by the figure or suggested in the figure. You will recognize that it is not limited to the order. For example, the metric (FIG. 32-41) can be monitored before, during, or after setting and monitoring the IEDF width and / or ion energy eV.

FIG. 44 illustrates various waveforms at different points in the systems disclosed herein. Switch mode Switching pattern 4410 illustrated for the switching component of the power supply, power supply voltage V _PS 4406 (also referred to herein as a periodic voltage function), ion current compensation Ic 4404, modified periodic voltage function. Considering the 4402, and the substrate voltage V _sub 4412, the IEDF has the illustrated width 4414 (may not be drawn to a constant scale) or the IEDF shape 4414. This width is wider than what this disclosure refers to as "narrow width". As shown, the substrate voltage V _sub 4412 is not constant when the ion current compensation Ic 4404 is _{greater than the ion current I I.} The IEDF width 4414 is proportional to the voltage difference of the inclined portion between the pulses _{of the substrate voltage V sub 4412.}

In view of this non-narrowing IEDF width 4414, the methods disclosed herein, the I C ₌ I _I up (or are related in accordance with equation 2 in alternative), the ion current compensation Ic is adjusted To request. FIG. 45 illustrates the effect of producing a final increasing change in the ion current compensation Ic to match the _{ion current I I.} When a I _C = _{I I,} a substrate voltage _V sub 4512 may become substantially constant, IEDF width 4514 narrows from non narrow width.

Once the narrow IEDF is achieved, the ion energy can be adjusted to the desired or defined value, as illustrated in FIG. Here, the scale of the power supply unit voltage (or, in the alternative, the bus voltage _Vbus of the switch mode power supply unit) is reduced (for example, the maximum negative amplitude of the pulse of the power supply unit voltage 4606 is reduced). As a result, [Delta] V ₁ is the peak-to-peak voltage so as to decrease from _{V PP1} to _{V PP2,} decreases to [Delta] V _2. As a result, the scale of the substantially constant substrate voltage V _sub 4608 is reduced, thus reducing the scale of ion energy from 4615 to 4614 while maintaining a narrow IEDF width.

Whether or not the ion energy is regulated, the IEDF width can be widened after the narrow IEDF width is achieved, as shown in FIG. Here, _(or in alternative, Equation 2 to produce a relationship between I _I and _{I C)} I I ₌ I _C in mind, it is possible to adjust the I _C, therefore, periodically Fixed The slope of the portion between the pulses of the voltage function 4702 is changed. As a result of the ion current compensation Ic and the ion current I _I being unequal, the substrate voltage moves from substantially constant to non-constant. A further result is that the IEDF width 4714 extends from the narrow IEDF 4714 to the non-narrow IEDF 4702. Higher I _C is adjusted away from _{I I,} IEDF4714 width increases.

FIG. 48 illustrates one pattern of power supply voltage that can be used to achieve more than one ion energy level, where each ion energy level has a narrow IEDF4814 width. The scale of the power supply unit voltage 4806 alternates in each cycle. This results in alternating ΔV and inter-peak voltages for each cycle of the modified periodic voltage function 4802. The board voltage 4812, in turn, has two substantially constant voltages that alternate between the pulses of the board voltage. This results in two different ion energies, each with a narrow IEDF4814 width.

FIG. 49 illustrates another pattern of power supply voltage that can be used to achieve more than one ion energy level, where each ion energy level has a narrow IEDF 4914 width. Here, the power supply voltage 4906 alternates between two different scales, but at one time for the two cycles prior to the alternate. As shown, the mean ion energy, V _PS 4906 is identical to the case which is then alternately per cycle. This indicates to achieve the same ion energy, an embodiment of one variety of other patterns which way can be used for V _PS 4906 only.

Figure 50 illustrates one combination of power supply voltage _V PS 5006 and the ion current compensation _I C 5004 which can be used to generate IEDF5014 defined. Here, the alternating power supply voltage 5006 provides two different ion energies. In addition, the IEDF5014 width of each ion energy can be extended by adjusting the ion current compensation 5004 away from the ion current I _I. If the ion energies are close enough as in the illustrated embodiment, the IEDF5014s of both ionic energies will overlap, resulting in one larger IEDF5014. Although capable of other embodiments and this embodiment, in order to achieve the IEDF5014 that the ion energy and definitions defined _and how to use a combination of adjustments to the V PS 5006 and _I C 5004 It is intended to show what can be done.

Next, with reference to FIGS. 17A and 17B, a block diagram illustrating another embodiment of the invention is shown. As shown, the substrate support 1708 in these embodiments comprises an electrostatic chuck 1782, and the electrostatic chuck supply 1780 is utilized to apply power to the electrostatic chuck 1782. In some variants, as depicted in FIG. 17A, the electrostatic chuck supply section 1780 is positioned to apply power directly to the substrate support section 1708, and in other variants, the electrostatic chuck supply section. The 1780 is positioned to apply power in connection with the switch mode power supply unit. Note that series chucking can be done by a separate feeder or by the use of a controller, resulting in a net DC chucking function. This DC-coupled (eg, no blocking capacitor) series chucking feature can minimize unwanted interference with other RF sources.

In FIG. 18, the plasma power supply unit 1884, which generally functions to generate the plasma density, is also configured to drive the substrate support unit 1808 together with the switch mode power supply unit 1806 and the electrostatic chuck supply unit 1880. A block diagram illustrating yet another embodiment of the present invention is shown. In this implementation, each of the plasma power supply unit 1884, the electrostatic chuck supply unit 1880, and the switch mode power supply unit 1806 can reside in separate assemblies or two of the supply units 1806, 1880, 1884. One or more may be constructed to reside within the same physical assembly. Advantageously, the embodiment depicted in FIG. 18 electrically grounds the top electrode 1886 (eg, showerhead) to obtain electrical symmetry and reduced damage levels due to less arc discharge events. Enables.

Referring to FIG. 19, a block diagram illustrating still another embodiment of the invention is shown. As depicted, the switch mode power supply unit 1906 in this embodiment does not require an additional plasma power supply unit (eg, without the plasma power supply units 102, 202, 1202, 1702, 1884). It is configured to bias the substrate and apply power to the substrate support and chamber 1904 to ignite (and sustain) the plasma. For example, the switch mode power supply unit 1806 can be operated in a duty cycle that is sufficient to ignite and sustain the plasma while providing a bias to the substrate support.

Next, with reference to FIG. 20, a block diagram of the input parameters and control outputs of the control portion, which may be utilized in connection with the embodiments described with reference to FIGS. 1-19, is depicted. The depiction of the control portion is intended to provide a simplified depiction of the exemplary control inputs and outputs that may be utilized in connection with the embodiments discussed herein. That is, it is not intended to be a hardware schematic. In a practical implementation, the depicted controls may be distributed among several individual components that may be achieved by hardware, software, firmware, or a combination thereof.

Referring to embodiments previously discussed herein, the controllers depicted in FIG. 20 are described with reference to FIG. 1, controller 112, reference to FIG. 2, controller 212 and ion. Energy control 220 component, described with reference to controller 812 and ion energy control portion 820, reference to FIG. 12, ion current compensation component 1260, described with reference to FIG. Of the current controller 1362, the Icc control depicted in FIG. 16, the controllers 1712A, 1712B depicted in FIGS. 17A and 17B, respectively, and the controllers 1812, 1912 depicted in FIGS. 18 and 19, respectively. Can provide one or more of the functionality of.

As shown, the parameters that can be utilized as inputs to the control portion include dVo / dt and ΔV, which are described in more detail with reference to FIGS. 13 and 14. As discussed, dVo / dt is utilized in connection with the ion energy distribution spread input ΔE and is an ion energy distribution as described with reference to FIGS. 12, 13, 14, 15A-C, and 16. A control signal Icc that controls the width of the spread may be provided. In addition, the ion energy control input (Ei) is utilized in connection with the optional feedback ΔV and, as described in more detail with reference to FIGS. 1-11, is an ion energy control signal (eg, FIG. 3). It can produce (affects the Vbus depicted) and result in the desired (defined) ion energy distribution. Another parameter that may be utilized in connection with many electrostatic chucking embodiments is a DC offset input that provides electrostatic force and holds the wafer in the chuck for efficient thermal control.

FIG. 21 illustrates a plasma processing system 2100 according to an embodiment of the present disclosure. The system 2100 includes a plasma processing chamber 2102 that encloses the plasma 2104 to etch the top surface 2118 of the substrate 2106 (and other plasma processes). The plasma is generated (eg, in-situ, remotely, or projected) by a plasma source 2112 powered by the plasma power supply 2122. _{The plasma sheath voltage V shear} measured between the plasma 2104 and the upper surface 2118 of the substrate 2106 accelerates the ions across the plasma sheath 2115 from the plasma 2104 and transfers the accelerated ions to the substrate 2106 (or photoresist). The substrate 2106 is etched by colliding with the upper surface 2118 (part of the substrate 2106 not protected by). Plasma 2104, with respect to ground (e.g., a plasma processing chamber 2102 wall), in the plasma potential _{V 3.} The substrate 2106 has a bottom surface 2120, which is supported via _{an electrostatic chuck 2111 and a chucking potential V chuck} between the top surface 2121 of the electrostatic chuck 2111 and the substrate 2106. It is held electrostatically. The substrate 2106 is dielectric and may therefore have a first potential V _{1 on} the top surface 2118 and a second potential V _{2 on} the bottom surface 2120. The top surface of the electrostatic chuck 2121 is in contact with the bottom surface 2120 of the substrate, thus, these two surfaces 2120,2121 are identical potential _{V 2.} The first potential V ₁ , the chucking potential V _chuck , and the second potential V ₂ are generated by the switch mode power supply unit 2130 and provided to the electrostatic chuck 2111 via the first conductor 2124. It is controlled via an AC waveform with DC bias or offset. Optionally, the AC waveform is provided via the first conductor 2124 and the DC waveform is optionally provided via the optional second conductor 2125. The AC and DC outputs of the switch mode power supply unit 2130 can also be controlled via a controller 2132 configured to control various aspects of the switch mode power supply unit 2130.

Ion energy and ion energy distribution is a first function of the potential V _1. Switch mode power supply unit 2130 provides the desired (or defined) adjusted AC waveform to produce a first potential V ₁ desired known to generate ion energy and ion energy distribution .. The AC waveform is RF and can have non-sinusoidal waveforms such as those illustrated in FIGS. 5, 6, 11, 14, 15a, 15b, and 15c. The first potential V ₁ may be proportional to the change in voltage ΔV illustrated in FIG. The first potential V ₁ is also equal to the plasma voltage V ₃ minus the plasma sheath voltage V _shear. However, the plasma voltage V ₃ is often smaller (eg, less than 20 V) compared to the plasma sheath voltage V _shear (eg, 50 V-2000 V), so that the first potential V ₁ and the plasma sheath voltage V _shear. Can be treated as approximately equal and equal for implementation purposes. Therefore, since the plasma sheath voltage V _shear affects the ion energy, the first potential V ₁ is proportional to the ion energy distribution. By maintaining a constant first potential V ₁ , the plasma sheath voltage V _shear is constant and therefore substantially all ions are accelerated via the same energy and thus narrow-range ion energy. The distribution is achieved. The plasma voltage V ₃ arises from the energy applied to the plasma 2104 via the plasma source 2112.

First potential V ₁ of the upper surface 2118 of the substrate 2106 is formed through the combination of the charge storage from electrons and ions to pass through the capacitive charging and sheath 2115 from the electrostatic chuck 2111. The AC waveform from the switch mode power supply unit 2130, a first potential _{V 1,} to remain substantially constant, the influence of ions and electrons move through the sheath 2115, the upper surface 2118 of the substrate 2106 Adjusted to offset the resulting charge accumulation.

The chucking force that holds the substrate 2106 in the electrostatic chuck 2111 is a function of the _{chucking potential V chuck.} The switch mode power supply unit 2130 provides a DC bias, that is, a DC offset, to the AC waveform so that _{the second potential V 2} is at a different potential than the first potential V _1. This potential difference causes a chucking voltage V _chuck. The chucking voltage V _chuck can be measured from the top surface 2221 of the electrostatic chuck 2111 to the reference layer inside the substrate 2106, where the reference layer includes any altitude inside the substrate except the bottom surface 2120 of the substrate 2106. (The exact location within the reference layer substrate 2106 can vary). Therefore, chucking is controlled by the second electric potential V _2, proportional thereto.

In one embodiment, the second potential V ₂ is equal to the DC offset of the switch mode power supply 2130 modified by the AC waveform (in other words, the AC waveform with the DC offset, where the DC offset is the AC waveform). Exceeds the peak-to-peak voltage). The DC offset can be substantially greater than the AC waveform so that the DC component of the switch mode power supply 2130 output dominates the second potential V2 and the AC component can be excluded or ignored.

The potential in the substrate 2106 fluctuates between _{the first and second potentials V 1} and V _{2. The chucking potential V chuck} is positive or negative (eg, V ₁ > V ₂ or V ₁ <because there is a Coulomb attraction between the substrate 2106 and the electrostatic chuck 2111 regardless of the chucking potential V _{chuck polarity.} It can be _{V 2).}

The switch mode power supply unit 2130, together with the controller 2132, can monitor various voltages deterministically and without sensors. In particular, the ion energy (eg, average energy and ion energy distribution) is deterministically monitored based on the parameters of the AC waveform (eg, gradient and step). For example, the plasma voltage V _3, ion energy, and the ion energy distribution is proportional to the parameters of the AC waveform produced by the switch mode power supply unit 2130. In particular, the ΔV of the falling edge of the AC waveform (see, eg, FIG. 14) is _{proportional to the first potential V 1} and thus the ion energy. By keeping the first potential V ₁ constant, the ion energy distribution is maintained in a narrow region.

The first potential V ₁ cannot be measured directly and the correlation between the switch mode power supply output and the first voltage V ₁ is based on the capacitance and processing parameters of the substrate 2106. , may vary, [Delta] V and the proportionality constant between the first potential V ₁ was, after a short processing time, can be determined experimentally. For example, if it is experimentally found that the falling edge ΔV of the AC waveform is 50V and the proportionality constant is 2 for a given substrate and process, the first potential V1 is 100V. Can be expected to be. The proportion between the step voltage ΔV and the first potential V ₁ (hence the ion energy eV) is expressed by equation 4. Therefore, along with the ion energy and ion energy distribution, the first potential V ₁ is determined based on the knowledge of the AC waveform of the switch mode power supply unit, without any sensor inside the plasma processing chamber 2102. be able to. In addition, the switch mode power supply unit 2130, together with the controller 2132, determines whether chucking has occurred (eg, whether the substrate 2106 is held by the electrostatic chuck 2111 via the _{chucking potential V chuck).} Can be monitored.

Dechucking is performed by eliminating or lowering the chucking potential V- _chuck. This can be done by setting the second potential V ₂ equal to the first potential V _1. In other words, the DC offset and AC waveform can be adjusted to bring _{the chucking voltage V chuck closer to 0V.} Compared to traditional dechucking methods, the system 2100 achieves faster dechucking and therefore more processing because both DC offset and AC waveforms can be adjusted to achieve dechucking. do. Also, when DC and AC power supplies are in switch mode power supply 2130, their circuits are more integrated, closer together and controlled via a single controller 2132 (typical of DC and AC power supplies). The output can be varied faster (compared to a target parallel array). The rate of dechucking enabled by the embodiments disclosed herein also allows dechucking after the plasma 2104 has been extinguished, or at least after the power from the plasma source 2112 has been turned off.

The plasma source 2112 can take various forms. For example, in one embodiment, the plasma source 2112 comprises an electrode inside the plasma processing chamber 2102, which establishes an RF field within the chamber 2102 that both ignites and sustains the plasma 2104. In another embodiment, the plasma source 2112 remotely creates an ionized electromagnetic field, projects or extends the ionized electromagnetic field into the processing chamber 2102, and uses the ionized electromagnetic field to ignite and sustain the plasma 2104 in the plasma processing chamber. Includes a remotely projected plasma source that does both. Further, the remotely projected plasma source also includes a field transfer portion (eg, a conductive tube) through which the ionized electromagnetic field passes on its way to the plasma processing chamber 2102, during which the ionized electromagnetic field is attenuated and the plasma processing chamber. The field intensity within 2102 is only one-tenth, or one-hundredth, or one-thousandth, or even less than the field strength when the field was first generated in a distantly projected plasma source. It becomes. Plasma source 2112 is not drawn to exact scale.

The switch mode power supply 2130 can float and is therefore biased at any DC offset by a DC power supply (not shown) connected in series between ground and the switch mode power supply 2130. be able to. The switch mode power supply unit 2130 is an AC power supply and a switch via the AC and DC power supplies inside the switch mode power supply unit 2130 (see, for example, FIGS. 22, 23, 26) or inside the switch mode power supply unit 2130. An AC waveform with a DC offset can be provided either via an external DC power supply unit of the mode power supply unit 2130 (see, eg, FIGS. 24 and 27). In certain embodiments, the switch mode power supply unit 2130 is grounded and can be coupled in series to a floating DC power source coupled in series between the switch mode power supply unit 2130 and the electrostatic chuck 2111.

The controller 2132 can control the AC and DC outputs of the switch mode power supply unit when the switch mode power supply unit 2130 includes both AC and DC power supplies. When the switch mode power supply unit 2130 is connected in series with a DC power supply, the controller 2132 may control only the AC output of the switch mode power supply unit 2130. In an alternative embodiment, the controller 2130 can control both the DC power supply unit coupled to the switch mode power supply unit 2130 and the switch mode power supply unit 2130. Those skilled in the art will recognize that although a single controller 2132 is illustrated, other controllers can also be implemented to control the AC waveform and DC offset provided to the electrostatic chuck 2111. ..

The electrostatic chuck 2111 is dielectric (eg, ceramic) and thus can substantially block the passage of DC voltage, or it is a semi-conductive material such as doped ceramic. be able to. In either case, the electrostatic chuck 2111 capacitively couples the voltage to the upper surface 2118 (usually dielectric) of the substrate 2106 _{to form the first voltage V 1} on the upper surface 2121 of the electrostatic chuck 2111. It can have a _second voltage V 2.

The shape and size of the plasma 2104 is not always drawn to the exact scale. For example, the edges of the plasma 2104 can be defined by a certain plasma density, in which case the illustrated plasma 2104 is not drawn taking into account any particular plasma density. Similarly, at least some plasma densities fill the entire plasma processing chamber 2102, regardless of the shape of the plasma 2104 shown. The shape of the illustrated plasma 2104 is primarily intended to indicate a sheath 2115 having a plasma density substantially smaller than that of the plasma 2104.

FIG. 22 illustrates another embodiment of the plasma processing system 2200. In the illustrated embodiment, the switch mode power supply unit 2230 includes a DC power supply 2234 and an AC power supply 2236 connected in series. The controller 2232 is configured to control the AC waveform with the DC offset output of the switch mode power supply 2230 by controlling both the AC power supply 2236 waveform and the DC power supply 2234 bias or offset. The present embodiment also includes an electrostatic chuck 2211 having a grid or mesh electrode 2210 embedded in the chuck 2211. The switch mode power supply unit 2230 provides both AC and DC bias to the grid electrode 2210. Substantially less than the DC bias, thus the DC bias with an AC component which may be ignored, to establish a third potential V ₄ on the grid electrode 2210. When the third potential V ₄ differs from the potential at the reference layer (excluding the bottom surface 2220 of the substrate 2206) somewhere in the substrate 2206, the chucking potential V _chuck and the Coulomb chucking force are established. The substrate 2206 is held by the electrostatic chuck 2211. The reference layer is a virtual plane parallel to the grid electrode 2210. The AC waveform is capacitively coupled from the grid electrode 2210 through a portion of the electrostatic chuck 2211 and through the substrate 2206 to control the _{first potential V1 on the top surface 2218 of the substrate 2206.} Since the plasma potential V ₃ is negligible with respect to the plasma sheath voltage V _{shear , the first potential V 1} and the plasma sheath voltage V _shear are considered to be approximately equal and, for practical purposes, equal. Therefore, the first potential V ₁ is equal to the potential used to accelerate the ions through the sheath 2215.

In certain embodiments, the electrostatic chuck 2211 can be doped to be sufficiently conductive so that any potential difference through the body of the chuck 2211 is negligible, thus the grid or mesh electrode 2210 is substantially the same. It can be the same voltage as the second potential V _2.

Any conductive planar device embedded within the electrostatic chuck 2211, parallel to the substrate 2206, biased by the switch mode power supply 2230, and configured to establish a _{chucking potential V-chuck.} Can be. Although the grid electrode 2210 is shown to be embedded in the lower portion of the electrostatic chuck 2211, the grid electrode 2210 can be located closer to or farther from the substrate 2206. The grid electrode 2210 also does not need to have a grid pattern. In certain embodiments, the grid electrode 2210 can be a solid electrode or have a non-solid structure with a non-grid shape (eg, checkered pattern). In certain embodiments, the electrostatic chuck 2211 is a ceramic or other dielectric, thus the third potential V ₄ on the grid electrode 2210 is the first potential V on the top surface 2221 of the electrostatic chuck 2211. Not equal to _1. In another embodiment, the electrostatic chuck 2211 is a slightly conductive, doped ceramic, so that the third potential V ₄ on the grid electrode 2210 is on the top surface 2221 of the electrostatic chuck 2211. It can be equal to the second potential V _2.

Switch mode power supply 2230 produces an AC output that can be non-sinusoidal. Since the DC power supply 2234 is AC conductive and the AC power supply 2236 is DC conductive, the switch mode power supply unit 2230 can operate the DC and the AC sources 2234 and 2236 in series. An exemplary AC power source that is not DC conductive is a linear amplifier, which can be damaged when DC voltage or current is provided. The use of AC and DC conductive power supplies reduces the number of components used within the switch mode power supply 2230. For example, if the DC power supply 2234 performs AC cutoff, the AC bypass or DC cutoff component (eg, a capacitor) may need to be arranged in parallel with the DC power supply 2234. If AC power 2236 performs DC cutoff, DC bypass or AC cutoff components (eg, inductors) may need to be aligned in parallel with AC power supply 2236.

In this embodiment, the AC power source 2238 generally applies a voltage bias in a controllable manner to provide the desired (defined) ion energy distribution for the ions striking the top surface 2218 of the substrate 2206. It is configured to be applied to the electrostatic chuck 2211. More specifically, the AC power source 2236 is configured to provide the desired (defined) ion energy distribution by applying one or more specific waveforms at a specific power level to the grid electrode 2210. .. More specifically, the AC power source 2236 applies a particular power level to provide a particular ion energy and is defined by one or more waveform data stored in a waveform memory (not shown). Use the voltage waveform to apply a specific power level. As a result, one or more specific ion impact energies may be selected to perform controlled etching of the substrate 2206 (or other plasma assisted process). In one embodiment, the AC power source 2236 can utilize a switchable mode configuration (see, eg, FIGS. 25-27). The switch mode power supply unit 2230, in particular the AC power supply 2236, can produce AC waveforms as described in the various embodiments of the present disclosure.

Those skilled in the art will recognize that the grid electrode 2210 is not required and other embodiments can be implemented without the grid electrode 2210. _Those skilled in the art will also recognize that the grid electrode 2210 is only one embodiment of a number of devices that can be used to establish the chucking potential V-chuck.

FIG. 23 illustrates another embodiment of the plasma processing system 2300. The illustrated embodiment includes a switch mode power supply unit 2330 for providing an AC waveform and a DC bias to the electrostatic chuck 2311. The switch mode power supply unit 2330 includes a DC power supply 2334 and an AC power supply 2336, both of which can be grounded. The AC power source 2336 generates an AC waveform provided to the first grid or mesh electrode 2310 embedded in the electrostatic chuck 2311 via the first conductor 2324. AC power 2336 establishes the potential _{V 4} on the first grid or mesh electrode 2310. The DC power supply 2334 creates a DC bias provided to the second grid or mesh electrode 2312 embedded in the electrostatic chuck 2311 via the second conductor 2325. DC power supply 2334, to establish a potential _{V 5} on the second grid or mesh electrode 2312. The potentials V ₄ and V ₅ can be independently controlled via AC and DC power supplies 2336, 2334, respectively. However, the first and second grid or mesh electrodes 2310, 2312 can also be capacitively coupled and / or via a portion of the electrostatic chuck 2311 between the grid or mesh electrodes 2310, 2312. , DC coupling may exist. If either AC or DC coupling is present, the potential _{V 4} and _{V 5} can be combined. Those skilled in the art will appreciate the first and second grid electrodes 2310, 2312 throughout the electrostatic chuck 2311, including arranging the first grid electrode 2310 closer to the substrate 2306 than the second grid electrode 2312. You will recognize that it can be arranged in various places.

FIG. 24 illustrates another embodiment of the plasma processing system 2400. In this embodiment, the switch mode power supply unit 2430 provides the AC waveform to the electrostatic chuck 2411 and the switch mode power supply unit 2430 output is offset by the DC bias provided by the DC power supply unit 2434. The AC waveform of the switch mode power supply unit 2430 has a waveform selected by the controller 2435 to strike the substrate 2406 with ions from the plasma 2404 having a narrow ion energy distribution. The AC waveform can be non-sinusoidal (eg, square or pulsed) and can be generated via the AC power supply 2436 of the switch mode power supply unit 2430. Chucking is controlled via a DC offset from the DC power supply 2434, which is controlled by the controller 2433. The DC power supply unit 2434 can be coupled in series between grounding and the switch mode power supply unit 2430. The switch mode power supply unit 2430 is floating so that its DC bias can be set by the DC power supply unit 2434.

Those skilled in the art will recognize that the illustrated embodiments show two independent controllers 2433, 2435, which can be combined within a single functional unit, device, or system such as the optional controller 2432. There will be. In addition, the controllers 2433 and 2435 can be coupled to communicate with each other and share processing resources.

FIG. 25 illustrates a further embodiment of the plasma processing system 2500. The illustrated embodiment includes a switch mode power supply unit 2530 that produces an AC waveform that may have a DC offset provided by the DC power supply unit (not shown). The switch mode power supply can be controlled via any optional controller 2535, including voltage and current controllers 2537, 2539. The switch mode power supply unit 2530 can include a controllable voltage source 2538 having a voltage output controlled by the voltage controller 2537 and a controllable current source 2540 having a current output controlled by the current controller 2539. .. The controllable voltage and current sources 2538, 2540 can be arranged in parallel. The controllable current source 2540 is configured to compensate for the ionic current between the plasma 2504 and the substrate 2506.

The voltage and current controllers 2537, 2539 can be coupled to each other and communicate with each other. The voltage controller 2537 can also control the switchable output 2539 of the controllable voltage source 2538. The switchable output 2539 can include two switches in parallel, as shown, or can convert the output of the controllable voltage source 2538 to the desired AC waveform (eg, non-sinusoidal). Can include circuits. Through the two switches, the controlled voltage or AC waveform from the controllable voltage source 2538 is combined with the controlled current output of the controllable current source 2540 to generate the AC waveform output of the switch mode power supply unit 2530. can do.

The controllable voltage source 2538 is illustrated to have a given polarity, but those skilled in the art will recognize that the opposite polarity also corresponds to that shown. Optionally, the controllable voltage and current sources 2538, 2540, along with the switchable output 2539, can be part of the AC power supply 2536, which is a DC located inside or outside the switch mode power supply 2530. It can be arranged in series with a power supply (not shown).

FIG. 26 illustrates yet another embodiment of the plasma processing system 2600. In the illustrated embodiment, the switch mode power supply unit 2630 provides an AC waveform with a DC offset to the electrostatic chuck 2611. The AC component of the waveform is generated via a parallel combination of a controllable voltage source 2638 and a controllable current source 2640 connected to each other through a switchable output 2639. The DC offset is generated by a DC power supply 2634 coupled in series between ground and the controllable voltage source 2638. In certain embodiments, the DC power supply 2634 can be floating rather than grounded. Similarly, the switch mode power supply unit 2630 can be floating or grounded.

The system 2600 may include one or more controllers for controlling the output of the switch mode power supply unit 2630. The first controller 2632 can control the output of the switch mode power supply unit 2630 via, for example, the second controller 2633 and the third controller 2635. The second controller 2633 can control the DC offset of the switch mode power supply unit 2630 as produced by the DC power supply 2634. The third controller 2635 can control the AC waveform of the switch mode power supply unit 2630 by controlling the controllable voltage source 2638 and the controllable current source 2640. In one embodiment, the voltage controller 2637 controls the voltage output of the controllable voltage source 2638 and the current controller 2639 controls the current of the controllable current source 2640. The voltage and current controllers 2637, 2639 can communicate with each other and can be part of a third controller 2635.

Those skilled in the art describe the various configurations of the controller for power supplies 2634, 2638, 2640, wherein the aforementioned embodiments are not limited, and various other configurations are also implemented without departing from the present disclosure. Will recognize that you can. For example, a third controller 2635 or voltage controller 2637 can control a switchable output 2639 between the controllable voltage source 2638 and the controllable current source 2640. As another embodiment, the second and third controllers 2633, 2635 can communicate with each other (though not shown as such). It should also be understood that the polarities of the controllable voltage and current sources 2638, 2640 are merely exemplary and do not imply a limitation.

The switchable output 2639 can be operated by alternating between two parallel switches to form an AC waveform. The switchable output 2639 can include any variety of switches, including, but not limited to, MOSFETs and BJTs. In one variant, the DC power supply 2634 can be arranged between the controllable current source 2640 and the electrostatic chuck 2611 (in other words, the DC power supply 2634 can float) and switch mode power supply. The unit 2630 can be grounded.

FIG. 27 illustrates another embodiment of the plasma processing system 2700. In this variant, the switch mode power supply 2734 is grounded again, but instead of being integrated into the switch mode power supply 2730, here the DC power supply 2734 is a separate component and the switch mode. A DC offset is provided not only for the components in the power supply unit 2730 but also for the entire switch mode power supply unit 2730.

FIG. 28 illustrates method 2800 according to an embodiment of the present disclosure. Method 2800 comprises the operation 2802 of placing the substrate in the plasma chamber. Method 2800 further comprises the operation 2804 to form the plasma in the plasma chamber. Such plasmas can be formed in situ or via a remote projection source. Method 2800 also includes switch power operation 2806. The switch power operation 2806 involves controllingably switching the power to the substrate so that a periodic voltage function is applied to the substrate. The periodic voltage function is considered a pulsed waveform (eg, a square wave) or an AC waveform and may include a DC offset generated by a DC power supply in series with the switch mode power supply. In certain embodiments, the DC power supply is built into the switch mode power supply unit and can therefore be in series with the AC power supply of the switch mode power supply unit. The DC offset creates a potential difference between the upper surface of the electrostatic chuck and the reference layer in the substrate, and this potential difference is referred to as the chucking potential. The chucking potential between the electrostatic chuck and the substrate holds the substrate in the electrostatic chuck and thus prevents the substrate from moving during processing. Method 2800 further comprises a modulation operation 2808 in which the periodic voltage function is modulated over multiple cycles. The modulation responds to the desired (or defined) ion energy distribution on the surface of the substrate so as to result in the desired (or defined) ion energy distribution based on the time average.

FIG. 29 illustrates another method 2900 according to one embodiment of the present disclosure. Method 2900 includes operation 2902 of placing the substrate in the plasma chamber. Method 2900 further includes operation 2904 to form the plasma in the plasma chamber. Such plasmas can be formed in situ or via a remote projection source. Method 2900 also includes operation 2906 to receive at least one ion energy distribution setting. The settings received in the receive operation 2906 may indicate one or more ion energies on the surface of the substrate. Method 2900 is further controllable so that the power to the substrate results in (1) the desired (or defined) distribution of ion energy based on the time average, and (2) the desired chucking potential based on the time average. Includes switch power operation 2908, which can be switched to. The power can have an AC waveform and a DC offset.

In conclusion, the invention provides, among other things, a method and apparatus for selectively producing the desired (or defined) ion energy using a switch mode power supply. A number of variations and substitutions have been made to the invention, its use, and its configuration to achieve substantially the same results as those achieved by the embodiments described herein. It is easy to recognize what can be done. Therefore, there is no intention to limit the present invention to the disclosed exemplary forms. Many variants, modifications, and alternative structures fall within the scope and spirit of the disclosed invention.

Claims (17)

A device for providing a modified periodic voltage function to an electrical node, wherein the electrical node is configured to couple to a support for the substrate of the plasma processing chamber.
A power supply unit that provides a modified periodic voltage function to the electrical node, wherein the modified periodic voltage function comprises a first portion containing a positive change in voltage and the first portion. A top portion starting at the end, a third portion below the end of the top portion containing a voltage change ΔV, and a fourth portion containing a tilt voltage starting at the end of the third portion. Including, power supply section and
In order to control the voltage on the surface of the substrate, the power supply unit is configured to control the change ΔV of the voltage and the tilt voltage based on the measured value of the modified periodic voltage function. A device with a controller. The device of claim 1, wherein the controller is configured to compare the modified periodic voltage function with a reference voltage waveform. The device of claim 1, wherein the controller is configured to monitor the instability of the tilt voltage in order to detect a failure or anomaly or change over time. The controller
Receiving ion energy settings and
It is configured to control the voltage change ΔV so that the calculated ion energy is equal to the ion energy setting.
The ion energy eV is

The device of claim 1, wherein C ₁ is an effective value of the support for the _{substrate and C 2} is a sheath capacitance value. The device according to claim 1, wherein the power supply unit includes a switch mode power supply unit including one or more switch components. The apparatus of claim 1, wherein the controllable DC voltage source includes a controllable DC voltage source, the controllable DC voltage source being in series with the inductor and for providing the tilt voltage. The device of claim 6, comprising a current source for controlling the tilt voltage. A device for providing a modified periodic voltage function to an electrical node, the electrical node being configured to couple to a substrate support in a plasma chamber.
A means for providing a modified periodic voltage function to the substrate support in the plasma chamber to bring voltage onto the surface of the substrate, wherein the modified periodic voltage function is of voltage. A first portion containing a positive change, a top portion starting at the end of the first portion, a third portion below the end of the top portion containing a voltage change ΔV, and the third portion. Means and means, including a fourth portion containing a tilt voltage starting at the end of the portion of .
In order to control the voltage on said surface of said substrate, said modified periodically voltage to control the variation ΔV and the slope voltage of the voltage based on the measured value of the modified periodic voltage function A device comprising a means for controlling the means for providing a function. A means for controlling the tilt voltage is provided until the following equation is satisfied.

The apparatus according to claim 8, wherein dV ₀ / dt is the slope of the tilt voltage, and C ₁ is the effective capacitance value of the substrate support portion. Comprising means for adjusting the tilt voltage as not met before Symbol equation Apparatus according to claim 9. 8. The apparatus of claim 8, wherein the means for providing the modified periodic voltage function comprises a switch mode power supply that includes one or more switch components. The means for providing the modified periodic voltage function includes a controllable DC voltage source, the controllable DC voltage source being in series with the inductor and providing the tilt voltage. The device according to claim 8, which is intended to be used. The device of claim 1, wherein the means for providing the modified periodic voltage function comprises a current source for providing the gradient voltage. A non-transient tangible computer-readable storage medium in which processor-readable instructions are encoded to perform a method for controlling a voltage on the surface of a substrate in a plasma processing chamber, the substrate. The support portion supports the substrate, and the method is:
The modified periodic voltage function is to control a modified periodic voltage function provided to the substrate support by the substrate bias supply to bring voltage onto the surface of the substrate. A first portion containing a positive change in voltage, a top portion starting at the end of the first portion, a third portion below the end of the top portion containing a change in voltage ΔV, and said. Including a fourth part containing a tilt voltage starting at the end of the third part, and
Taking the measured value of the modified periodic voltage function and
Non-transient tangible, including adjusting the voltage change ΔV and the slope voltage based on the modified periodic voltage function measurements to control the voltage on the surface of the substrate. Computer-readable storage medium. The non-transient, tangible computer-readable storage medium of claim 14, wherein a readable instruction for comparing the modified periodic voltage function with a reference voltage waveform is encoded. The non-transient tangible computer read according to claim 14, wherein a processor readable instruction for monitoring the instability of the tilt voltage is encoded to detect a failure or anomaly or change over time. Possible storage medium. Receiving ion energy settings and
A processor-readable instruction for controlling the voltage change ΔV is encoded so that the calculated ion energy is equal to the ion energy setting.
The ion energy eV is

The non-transient tangible computer readable storage medium according to claim 14, wherein C ₁ is an effective capacitance value of the substrate support and C _{2 is a sheath capacitance value.}

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