JP4447829B2 - Plasma processing system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates generally to plasma material processing apparatus, and more particularly to an apparatus and method for inductively coupled plasma generation in which inductive plasma is excited by supplying electromagnetic energy to a branch RF antenna.
[0002]
[Prior art]
Many types of plasma material processing methods are widely used for semiconductor manufacturing and plasma generation, including sputter etching, plasma chemical etching, reactive ion etching, plasma deposition, ionized sputter deposition, and magnetron type plasma etching. Different types of known plasma sources include capacitively coupled plasma (CCP) sources, microwave plasma sources (including the use of ECR (electron-cyclotron resonance) to improve the efficiency of deposition capability within the plasma), Similar to others, including surface wave plasma sources and helicon plasma sources, they are used in these processes, such as a general induction plasma (ICP) source. In many sources, radio frequency (RF) power can be supplied to the RF antenna such that the process gas supplied to the plasma source space is excited, separated, and ionized. This excitation is caused by a radio frequency electromagnetic field formed by the RF current of the antenna generating the plasma.
[0003]
The inductively coupled plasma source and antenna geometry are important factors in process uniformity and plasma determination within the process chamber. The growing demand to process increasingly larger wafers or LCD (liquid crystal display) substrates and to provide increasingly higher plasma uniformity challenges the latest ICP-type antenna designs and promotes source development.
[0004]
[Patent Document 1]
US Patent Application No. 60 / 325,199, filed September 28, 2001
[0005]
[Patent Document 2]
US Patent Application No. 60 / 325,188, filed September 28, 2001
[0006]
[Problems to be solved by the invention]
Conventional helical RF antennas are too long for larger wafers or LCD substrates and cannot generate uniform plasma. Furthermore, such RF antennas cannot provide the plasma homogeneity required in both flat and dome shaped dimensions. Problems with RF antennas arise because of the length of the antenna elements relative to electromagnetic waves and due to the effects of standing waves. The effects of standing waves are stronger during increased frequency manipulation of increased wafer or substrate size, limiting the application range of RF antennas and reducing uniformity.
[0007]
Furthermore, the radially extended RF antenna becomes inefficient because it cannot uniformly cover the entire plasma processing area on the substrate. Area coverage is reduced from the end to the outside so that there is sufficient coverage closer to the center of the antenna, but there is insufficient coverage between any two radially extending “arms” of the antenna.
[0008]
Domed antennas are likewise not feasible to adequately provide the increased size of the plasma region and substrate.
[0009]
Finally, antennas wired around the sides of the vacuum chamber become inefficient because they cannot provide an appropriate RF field to the inner half of the plasma volume.
[0010]
What is needed is a redesigned RF antenna apparatus and method for generating more uniform plasma coverage over a larger area.
[0011]
The present invention is made in consideration of the above-mentioned problems that arise in conventional plasma material processing of RF inductively coupled type, where inductive plasma excitation is formed by applying power to the RF antenna.
[0012]
Accordingly, it is an object of the present invention to provide a novel branch RF antenna for use in plasma material processing operations. Another object of the present invention is to improve the uniformity of plasma generation. Another object of the present invention is to reduce the effects of standing waves on improved plasma material processing.
[0013]
[Means for Solving the Problems]
In accordance with the present invention, a branched radio frequency (RF) antenna coupled to an RF power source to form an electromagnetic field that excites a processing gas in the processing chamber and converts the processing gas into plasma, and the electromagnetic field is passed through the plasma reactor. A plasma reactor is provided for generating a uniform plasma using an inductively coupled plasma (ICP) source that includes a window that can pass through.
[0014]
Further provided is a method for generating a uniform plasma using an inductively coupled plasma (ICP) source, the method comprising placing the sample on a mounting surface and continuously evacuating the plasma reactor to a reduced pressure condition. Including a step, introducing a gas into the plasma reactor, and applying RF power to the branch RF antenna, wherein the branch RF antenna provides a uniform electric field to the gas in the process chamber in which the uniform plasma is generated.
[0015]
In a first aspect of the invention, the branch RF antenna includes a plurality of main branches and a plurality of sub-branches having embedded cooling passages extending from the central feed element. This preferred embodiment provides a more uniform plasma generation and more uniform coverage of the plasma region.
[0016]
A plasma processing system for performing plasma processing on an object to be processed includes a processing chamber formed in a process container, a gas supply system for supplying a processing gas to the process container, an exhaust system for exhausting the processing chamber and controlling pressure. A susceptor disposed in the processing chamber and having a mounting surface for supporting the object to be processed; and an ICP RF generation source having a branch antenna that holds a large uniform plasma during the process.
[0017]
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out below.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate this preferred embodiment of the invention, the general description given above and the preferred implementation shown below. Together with a detailed description of the form, it serves to explain the principles of the invention.
[0019]
Embodiments of the present invention will be described below with reference to the accompanying drawings. In the following description, components having substantially the same function and apparatus are denoted by the same reference numerals, and redundant description will be given only when necessary.
[0020]
FIG. 1A is a schematic diagram illustrating a plasma etching system 100 according to a preferred embodiment of the present invention. The plasma etching system 100 includes an ICP source having a branch antenna.
[0021]
An airtight processing chamber 102 of the plasma etching system 100 is constituted by a substantially cylindrical process vessel 104 and an upper plate 106. The process vessel 104 and the upper plate 106 are formed of a conductive material such as stainless steel, and are grounded through a ground wire 108.
[0022]
Faraday shield 140 is electrically coupled to the sidewall of process vessel 104.
[0023]
In the illustrated embodiment, the Faraday shield 140 is composed of a number of conductive elements 145 and spaces 147 arranged in a first pattern. The conductive element 145 is connected to the process vessel 104 via the grounding means 148. Thus, the conductive element 145 is electrically grounded. Alternately, a dual Faraday shield 140 consisting of at least two layers of conductive elements can be used.
[0024]
In other embodiments of the present invention, the branch RF antenna can be used without a Faraday shield and can be placed over a dielectric window, below a dielectric window, or even a non-dielectric window. As such, the branch RF antenna is placed in the processing chamber. Desirably, the conductive elements are the same size. Alternately, the conductive elements 145 can have different sizes. Further, the Faraday shield 140 can also be DC biased or RF power can be applied.
[0025]
Dielectric window 155 is coupled to process vessel 104 and includes a ceiling for process chamber 102. Desirably, the dielectric window 155 includes a dielectric material and includes a dielectric window for the antenna 110.
[0026]
In a preferred embodiment, the gas supply line 133 is coupled to the process chamber 102 and supplies process gas. The gas supply line 133 is connected to the gas generation source device 134 through at least one on-off valve (not shown) and at least one flow control valve (not shown). This gas generation source device 134 includes a plurality of different gases supplied to the processing chamber 102, such as CF ₄ , C ₄ F ₈ , CO, O ₂ , Ar, and N ₂ Have a gas generation source for.
[0027]
In a variation of the embodiment, the gas supply line 133 is coupled to a Faraday shield 140 that is used to supply process gas to the process chamber 102.
[0028]
The branch RF antenna 110 is disposed on the Faraday shield 140. In a preferred embodiment, the branch RF antenna is composed of a plurality of main branches and sub branches.
[0029]
Preferably, the branched RF antennas to be branched are uniformly arranged so as to be advantageous due to the RF power supply and simple design. It is desirable to maintain an equal load in the example of n main branches, particularly when each main branch covers n portions of the plasma region. However, the principle of equal load is not a limitation of the present invention. In other examples, different loads can be used and other antenna shapes can be used.
[0030]
The branch RF antenna 110 is connected to the RF power source 114 through the matching device 112 and the transmission line 113. Desirably, the RF power source 114 outputs plasma generated RF power to the branch RF antenna 110 and operates in the RF frequency range of 10 to 1000 MHz. Alternately, a different number of matching devices and / or transmission lines can be used.
[0031]
In other embodiments, the branch RF antenna 110 can be connected to at least one other RF power source (not shown) so that different branches can be supplied by different RF power sources or by different frequencies.
[0032]
The susceptor 116 is made of a conductive material and is disposed in the lower part of the processing chamber 102. The susceptor can be grounded or electrically isolated when no RF power is applied (as in FIG. 1B). However, in the preferred embodiment (FIG. 1A), the susceptor is below the RF potential supplied by the second RF power supply 126 through the corresponding matching circuit 124. The RF frequency of the second RF power source 126 is in the range of 500 kHz to 10 MHz. This applies an additional bias potential to the wafer W and improves the directionality of the charged molecule bundle traveling from the plasma (not shown) to the wafer W.
[0033]
The upper surface of the susceptor 116 functions as a wafer holding surface, and an insulating layer 115 made of, for example, polyimide is attached to the upper surface. A conductive electrostatic chuck electrode 117 and a resistive layer 121 are disposed on the insulating layer 115. This chuck electrode can be made by forming a silver film or a palladium film on the lower surface of the resistive layer. A conductive line (not shown) covered by the insulated cable is provided in the susceptor and connected to the chuck electrode 117. On the other hand, this conductive line is connected to a DC power source by a switch (not shown).
[0034]
A gas supply passage (not shown) is provided to the rear surface of the wafer W through the resistive layer 121 to supply a thermally conductive gas such as helium. Furthermore, a plurality of pusher pins for moving the wafer up and down with respect to the uppermost surface of the resistive layer, for example, three pusher pins are provided.
[0035]
The susceptor is mounted on a cooling block 119 made of a thermally conductive material such as aluminum that supports a tube having a circulating coolant such as liquid nitrogen. The cooling block 119 is connected to the bottom of the processing chamber by an insulating member 118.
[0036]
The vertical movement shaft 120 is movable in the vertical direction by a vertical movement mechanism (not shown). Since this shaft is designed to move all of the susceptor 116, the electrostatic chuck 117, the cooling block 119, and the mounting table 123 including the wafer W in the vertical direction, it is between the wafer W and the branch RF antenna 110. Can be adjusted appropriately.
[0037]
The bellows 122 is composed of an airtight member. The bellows 122 is connected to the insulating member 118, surrounds the vertical movement shaft 120, and is connected to the bottom surface of the processing chamber 102. Therefore, even if the susceptor 116 is moved in the vertical direction, the airtightness of the processing chamber 102 is not impaired.
[0038]
The processing chamber 102 is connected to an exhaust line 136 of the exhaust system. The exhaust line 136 is connected to the exhaust pump 138 through an on-off valve and a flow rate control valve (not shown). The exhaust pump 138 is, for example, 10 mTorr
To 100 mTorr, the processing chamber 102 can be evacuated to set the processing chamber 102.
[0039]
In a preferred embodiment, controller 170 is coupled to first RF power source 114, matching circuit 112, gas generation source 134, exhaust pump 138, second RF power source 126, and second matching circuit 124. The controller 170 includes hardware and software that controls the operation of the first RF power source 114, the matching circuit 112, the second RF power source 126, and the second matching network 124, the gas generation source 134, and the exhaust pump 138. Including. For example, the controller 170 can control the frequency, phase, amplitude, and bias of the signal supplied by the RF power source. Further, the controller 170 can control the processing gas and flow rate in the processing chamber 102. Further, the controller 170 can control the temperature of the Faraday shield 140, the branch RF antenna 110, and the wafer W by controlling the flow of fluid through a cooling passage (not shown).
[0040]
In the plasma etching system shown in FIG. 1A, processing is performed as follows. First of all, the wafer W is arranged in the processing chamber 102 and placed on a mounting table (work table) 123. Thereafter, the processing chamber 102 is exhausted by an exhaust system connected to the processing chamber 102, thereby setting the entire interior of the processing chamber 102 to a predetermined reduced pressure atmosphere.
[0041]
Since the mounting table 123 on which the wafer W is mounted is moved in the vertical direction to the working position, the distance between the wafer W and the branch RF antenna is set to a predetermined value defined by this processing.
[0042]
Although the processing chamber 102 is continuously exhausted, the processing gas is supplied from the processing gas supply system 134 to the processing chamber 102. In a preferred embodiment, process gas is supplied from the gas supply system to the at least one gas supply pipe and from the at least one gas supply pipe to the process chamber 102. In other embodiments, process gas is supplied to the Faraday shield. Next, the processing gas enters the processing chamber 102 from the Faraday shield 140 through a gas supply hole (not shown in FIG. 1).
[0043]
In this state, plasma-generated RF power is supplied to the branch RF antenna 110, so that the process gas supplied to the process chamber 102 is excited, separated, and ionized, thereby generating a uniform, wide-area plasma. .
[0044]
In order to prevent the Faraday shield 140 from being inductively heated and to effectively use the input energy from the branch RF antenna 110 that generates plasma, the current path is formed in the same direction as the direction of the RF electric field. Should not. For example, the branch RF antenna 110 may be arranged such that the elements have a substantially radial shape (expanded in the radial direction) and have a geometric center that is integral with the center of the wafer W. In such a case, the RF electric field generated by the branch RF antenna 110 has an electric field direction that is also radially. For this reason, since the corresponding Faraday shield 140 is provided with a number of slots and is arranged concentrically, the conductive elements in the Faraday shield mainly have an azimuthal direction. In other words, the slot 147 extends in a direction that is substantially perpendicular to the direction of the RF electric field generated by the branch RF antenna 110. In this arrangement, the electromagnetic field generated by the branch RF antenna 110 is transmitted to the processing chamber 102 without being blocked, so that the RF electric field is generated in the processing chamber 102 as long as the capacitive component is significantly reduced. . As a result, the input energy from the branch RF antenna 110 is effectively utilized to generate plasma.
[0045]
In other embodiments, the top plate 106 is not necessary. For example, the processing chamber can be formed using dielectric windows, insulating layers, branch RF antennas, and / or gas distribution devices.
[0046]
FIG. 1B is a schematic diagram illustrating a plasma etching system according to another embodiment of the present invention. FIG. 1B shows a plasma etching system in which the RF power supply system is not coupled to the susceptor.
[0047]
FIG. 1C is a schematic diagram illustrating a plasma etching system according to a modification of the embodiment of the present invention. FIG. 1C includes all features shown for the apparatus of FIG. 1A. However, FIG. 1C shows different geometries for the branch RF antenna, and in the illustrated embodiment, the dielectric window and Faraday shield geometries are not flat but curved. The curvature and shape of the RF antenna are designed so that a uniform plasma is supplied to the surface of the wafer W.
[0048]
FIG. 2 shows a simplified diagram of a branch RF antenna according to a preferred embodiment of the present invention. FIG. 2A shows a branch RF antenna having cooling passages in all branches according to a preferred embodiment of the present invention. FIG. 2B shows a branch RF antenna having cooling passages in several branches according to a variation of the embodiment of the present invention.
[0049]
The branch RF antenna 200 includes a plurality of main branches 208 and a plurality of sub branches 210. Each main branch includes a first number of branches extending radially from the central feed element 202 in substantially the same direction as the branch point 214. Desirably, each branch of the main branch is in a different plane, but all of the branches of the main branch have the same protrusion on a plane parallel to the substrate. For example, the branches of the main branch are electromagnetically and / or electrically coupled to each other but are not physically coupled to each other.
[0050]
At branch point 214, at least one sub-branch 210 is coupled to each main branch. Each sub-branch extends in a different direction from the branch point 214. Desirably, a significant portion of each sub-branch is in the same plane. As shown in FIG. 2, three sub-branches are coupled to each main branch at a branch point, but this is not necessary for the present invention. In other embodiments, at least two sub-branches are coupled to each main branch at one or more branch points.
[0051]
In the preferred embodiment, the branch antenna of FIG. 2A is powered by the RF power source 114 (FIG. 1) through the matching circuit 112 at the center 202 and grounded at an output point 206 on the periphery of the antenna. This provides RF current through main branch 208 and sub-branch 210. Desirably, each branch of the main branch is individually coupled to the central feed element 202.
[0052]
In other embodiments, the external point 206 is grounded through a capacitor (not shown).
[0053]
The main branch 208 has a symmetrical geometry and loading to greatly simplify antenna tuning and ensure a more uniform plasma generation. Each main branch 208 covers a different azimuthal area.
[0054]
In other embodiments, a different number of main branches 208 and / or a different number of sub-branches can be used.
[0055]
In the preferred embodiment, the antenna 200 has a cooling path 212 that extends through all its branches. For high RF power, the cooling path 212 can be provided on both the main and sub-branches 208 and 210. However, the absence of the cooling path 212 in some sub-branches 210 (FIG. 2B) is due to the high thermal conductivity of the metal part of the antenna 200 and the sub-branches 210 that cool due to the proximity of the sub-branches 210 to other cooling branches. It is acceptable when using moderate RF power.
[0056]
In other embodiments, the branch RF antenna 200 can be placed on a dome-like surface or other non-planar surface. In the case of a dome-like surface, the common center of all branches is at the center of the dome (the center of symmetry). In the case of a stepped surface, the common center of all main branches is at the center of the top step.
[0057]
In other embodiments, the branches of any branch RF antenna can be powered around the antenna and grounded at a common center. However, this embodiment can complicate the structure due to the increased number of points that require connection to a power source.
[0058]
In other embodiments, the main branch can be powered by different RF sources. Furthermore, the main branch can be powered by radio frequencies having different phases and / or different frequencies.
[0059]
The main branch and the sub-branch are manufactured using a metal such as anodized aluminum. For example, the antenna branch may have a single conductive surface that can be manufactured using a metal such as anodized aluminum. The antenna branches 208, 210 can be manufactured differently for different antenna shapes.
[0060]
As shown in FIG. 2, the bond angle between the sub-branch and the main branch is less than 90 °, but this is not necessary for the present invention. In other embodiments, these bond angles may be equal to and / or greater than 90 °.
[0061]
As shown in FIG. 2, each main branch includes one branch point, but this is not necessary for the present invention. In other embodiments, at least one main branch is comprised of two or more branch points.
[0062]
FIG. 3 shows a simplified diagram of a second type of branched RF antenna according to another embodiment of the present invention. FIG. 3 is a simplified diagram illustrating a branched RF antenna according to a preferred embodiment of the present invention. FIG. 3 shows a branch RF antenna having cooling passages in all branches.
[0063]
The branch RF antenna 300 includes a plurality of main branches 308 and a plurality of curved sub-branches 310. Each main branch includes a first number of branches that extend radially from the central feed element 302 to the branch point 314 in substantially the same direction. Desirably, each branch of the main branch is in the same plane, but all of the branches of the main branch have the same protrusion on a plane parallel to the substrate. For example, the branches of the main branch are electromagnetically and / or electrically coupled to each other but cannot be physically connected to each other.
[0064]
At branch point 314, at least two bent sub-branches 310 are connected to each main branch. Each bent sub-branch extends in a different direction from the branch point 314. Desirably, a substantial portion of each bent sub-branch 310 is in the same plane, but the bent sub-branch 310 has the same protrusion on a plane parallel to the substrate. As shown in FIG. 3, two bent sub-branches 310 are connected to each main branch 308 at each branch point 314, but this is not necessary for the present invention. In other embodiments, at least two sub-branches are connected to each branch of the main branch at one or more branch points.
[0065]
Desirably, the branch RF antenna 300 is powered by the RF power source 114 (FIG. 1) through the matching circuit 112 at the central branch 308 and grounded at the output point 306. This provides RF current through main branch 308 and sub-branch 310. Each branch of the main branch can be separately connected to the central feed element 302. In other embodiments, output point 306 is connected to ground through a capacitor (not shown).
[0066]
The main branch 308 has a symmetrical geometry and loading to greatly simplify antenna tuning and ensure a more homogeneous plasma generation. Each main branch 308 covers a different azimuthal region.
[0067]
In other embodiments, a different number of main branches 308 and / or a different number of sub-branches can be used.
[0068]
In the preferred embodiment, the antenna 300 has a cooling path 312 that extends through all its branches. For high RF power, the cooling path 312 can be provided in both the main and sub-branches 308 and 310. However, the absence of the cooling path 312 in some of the sub-branches 310 (FIG. 4) is due to the high thermal conductivity of the metal part of the antenna 300 and the sub-branches 310 that cool due to the proximity of the sub-branches 310 to other cooling branches. It is acceptable if moderate RF power is used.
[0069]
In other embodiments, the branch RF antenna 300 can be placed on a dome-like surface or other non-planar surface. In the case of a dome-like surface, the common center of all branches is at the center of the dome (the center of symmetry). In the case of a stepped surface, the common center of all main branches can be at the center of the top step.
[0070]
In other embodiments, the main branch can be powered by different RF sources. Furthermore, the main branch can be powered by radio frequencies having different phases and / or different frequencies.
[0071]
In other embodiments, the branch RF antenna 300 includes a plurality of co-planar main branches 308 and a plurality of bent sub-branches 310 extending radially from the central feed element 302. In this example, the branching occurs in the plane of the branching RF antenna 300 or on the same surface.
[0072]
Reduced termination 306 simplifies the structure of antenna 300. Preferably, all bent branch elements 310 have a symmetric geometry and loading that greatly simplifies antenna tuning and ensures a more homogeneous plasma generation. However, symmetry is not required in other embodiments.
[0073]
In other embodiments, similar to the branch antenna description of FIG. 2, an RF power feed can be placed that goes to termination 306 as long as center point 302 is grounded. In yet another embodiment, the ground can be placed through a capacitor (not shown).
[0074]
The RF antenna 300 shown in FIG. 3 can be adjusted to a dome-like surface or other non-planar surface.
[0075]
FIG. 4 shows a simplified diagram of a third branch RF antenna according to another embodiment of the present invention.
[0076]
The branch RF antenna 400 includes a plurality of main branches 408 and a plurality of sub branches 410. The main branches 408 extend radially from the central feed element 402 in the same plane. Each main branch 408 includes a branch point 414. A number of sub-branches 410 are coupled to the branch point 414 of each main branch 408. Further, the central feed element 402 can be coupled to the transmission line 113 (FIG. 1).
[0077]
In the illustrated embodiment, the branch RF antenna 400 has eight main branches 408 that provide a common geometric center. Each major branch 408 begins in the central feed element 402 and extends radially. The branch point 414 is at a first length 424 from the central feed element 402. The main branch 408 has a symmetrical geometry and loading that greatly simplifies antenna tuning and ensures a more homogeneous plasma generation. Each main branch 408 covers a different azimuthal region.
[0078]
In the illustrated embodiment, three sub-branches 410 extend from each branch point 414. The secondary branch length 426 is the distance from the branch point 414 to the grounded external point 406 on the antenna periphery 404. Along the antenna periphery 404, each sub-branch 410 has a separate termination 406. Moderate differences in the geometry and loading of the sub-branch 410 are acceptable in this embodiment.
[0079]
In other alternative embodiments, a different number of main branches 408 and / or a different number of sub-branches can be used.
[0080]
Further, the branch RF antenna 400 may include a cooling passage 412 that may extend through one or more main branches 408. For high RF power, the cooling path 412 can be provided in both the main and sub-branches 408 and 410.
[0081]
In the illustrated embodiment, the branch RF antenna 400 in the same flat plane provides more uniform coverage of a larger area, thus providing more uniform plasma generation as needed for larger substrates.
[0082]
However, in other alternative embodiments, the branch RF antenna 400 can be placed on a dome-like surface or other non-flat surface rather than the preferred flat surface. In the case of a dome shape, the common center of all main branches is at the center of the dome (center of symmetry). In the case of a stepped surface, the common center of all main branches is at the center of the top step.
[0083]
FIG. 5 shows a simplified diagram of a fourth type of branched RF antenna according to another embodiment of the present invention.
[0084]
The branch RF antenna 500 includes a plurality of main branches 508 and a plurality of sub-branches 510. The main branches 508 are in the same plane and extend radially from the central feed. Each main branch 508 includes a branch point 514. A number of sub-branches 510 are connected to a branch point 514 of each main branch 508. The central feed element 502 is connected to the transmission line 113 (FIG. 1) and the end 506 on the periphery is grounded.
[0085]
In the illustrated embodiment, the branch RF antenna 500 has three main branches 508 that provide a common geometric center. Each main branch 508 extends mainly radially starting from the central feed element 502. The main branch 508 has a symmetrical loading that greatly simplifies antenna tuning and ensures more homogeneous plasma generation. Each main branch 508 covers a different azimuth area.
[0086]
In the illustrated embodiment, three sub-branches 510 extend from each branch point 514. Along each antenna periphery 504, each sub-branch 510 has a separate termination 506. Moderate differences in the geometry and loading of the sub-branch 510 are acceptable in this embodiment.
[0087]
In other alternative embodiments, a different number of main branches 508 and / or a different number of sub-branches can be used.
[0088]
Further, the branch RF antenna 500 includes a cooling path that may extend through some of the main branch 508 and the sub-branch 510. For high RF power, cooling paths can be provided on both the main and sub-branches 508 and 510.
[0089]
In the illustrated embodiment, the branch RF antenna 500 in the same flat plane provides more uniform coverage of a larger area, thus producing more homogeneous plasma as needed for larger substrates.
[0090]
However, in other alternative embodiments, the branch RF antenna 500 can be placed on a dome-like surface or other non-flat surface rather than the preferred flat surface. In the case of a dome-like surface, the common center of all main branches is at the center of the dome (symmetrical center). In the case of a stepped surface, the common center of all main branches is at the center of the top step.
[0091]
FIG. 6 shows another shape for a fourth type of branched RF antenna according to another embodiment of the present invention. As shown, there is no visible breakpoint shown between the main branch and the sub-branch, and the protrusions on the wafer plane are not combined into a single branch, but there is a more significant branch grouping. is there.
[0092]
Near the common center 602, the antenna branches are grouped significantly (when shown in FIG. 6, there are three groups 608 branches corresponding to the main branch 508 of FIG. 5). In the outer region, antenna branches 610 travel further away from each other, similar to sub-branch 510 of FIG.
[0093]
All branches are collected at the center 602 and grounded at the end 606 of the periphery 604. Alternately, antenna branches are provided at termination 606 and can be grounded at a common center 602. Alternately, they are grounded through a capacitor (not shown). A cooling path (not shown) is passed through the antenna branch.
[0094]
In the illustrated embodiment, a branch RF antenna 600 that is in the same flat plane provides more uniform coverage of a larger area, thus producing more homogeneous plasma as needed for larger substrates.
[0095]
However, in a variation of the embodiment, the branch RF antenna 600 can be placed on a dome-like surface or other non-flat surface rather than the preferred flat surface. In the case of a dome-shaped surface, the common center of all main branches is at the center of the dome (symmetrical center). In the case of a stepped surface, the common center of all main branches is at the center of the top step.
[0096]
FIG. 7 shows a simplified diagram of a first type of branching according to a preferred embodiment of the present invention. Each main branch 708 consists of several branches having the same (or close to the same) protrusion on the wafer surface. At the branch point 714, the branches are divided from each other, so that a plurality of sub-branches 710 are formed. The cooling path 712 can pass through the antenna branch to ensure an acceptable temperature situation for the antenna.
[0097]
With the present invention, several types of antenna branches can be considered. If the antenna's electric field protrusion on the plane of the wafer that looks like a main branch is branched (ie, the sub-branch splits the main branch), the preferred type of branch corresponds to this case (FIG. 7). To do. In practice, each main branch consists of several branches (see FIG. 7). That is, this branch is the protrusion of the branch on the wafer plane that appears to be almost the main branch. This results in a more uniform electromagnetic (EM) electric field on the wafer and a more uniform plasma generation across the entire area of both wafers, each closer to the wafer center and closer to its periphery.
[0098]
If the main branch and the sub-branch of the antenna are in substantially the same plane, the other type of branch is a branch in the same plane.
[0099]
Furthermore, the branching principle can be modified. For example, if the protrusions on the wafer plane are not correctly connected and become a single main branch, but still have a significant branch grouping (see FIG. 6 compared to FIG. 5). It is also covered under the present invention.
[0100]
Another type of branch is shown in FIG. In this case, the total length of the antenna (such as a flat spiral antenna) is divided into several branches, so the electrical length of each branch is short enough to avoid the effects of standing waves. Since antenna tuning and uniform plasma generation are most easily maintained, the principle of equal (or near equal) electrical loading at each branch is beneficial in the most common situations and is selected as the preferred embodiment.
[0101]
Further, non-uniform plasma generation (eg, higher plasma generation rate around the wafer) may be taken. In this case, the equal load principle for branching may not be applicable.
[0102]
FIG. 8 shows a simplified diagram of a first type of branch RF antenna and a second type of branch that differs significantly from the branches shown in FIGS. 2-6 according to embodiments of the present invention. The branch RF antenna 800 includes a plurality of branches 810, 820 and 830, each branch being part of a planar helix. Each branch 810, 820 and 830 has a different radial region. Branches 810, 820 and 830 are provided at the first end, ie, 812, 822 and 832 respectively, while the other ends, 814, 824 and 834 are electrically grounded. Further, a single RF power generator can power all branches, or different RF power generators (with the same or different RF frequency, phase, or amplitude) can power different branches. The power supply terminal and ground terminal of each branch whose power supply terminal and ground terminal are exchanged can be switched.
[0103]
In the illustrated embodiment, the outer branch 830 includes a single turn, the intermediate branch 820 includes approximately one and a half turns, and the inner branch 810 includes approximately two turns. One turn is a single rotation in the negative or positive direction. On the other hand, branches 810, 820 and 830 may have different numbers of turns. The outer branch 830 has a first end 832 and a second end 834. The intermediate branch 820 has a first end 822 and a second end 824. Inner branch 810 has a first end 812 and a second end 814. In order to obtain equal loads, the preferred shape for antenna 800 should have a different number of turns for each branch, and inner branch 810 has the maximum number of turns.
[0104]
Furthermore, different matching networks and / or RF sources drive different branches if the load for this branch varies with the reliability of certain radial (radial) processes as well as the plasma and gas diffusion rates. it can. Specific tuning of the antenna branch parameters provides a unique plasma density profile in the radial direction as it is necessary to compensate for the reliability of the radial process. If the generation of a radial non-uniform plasma is required in special circumstances, the embodiment shown in FIG. 8 can be used for convenience.
[0105]
The surface of the branched RF antenna 800 shown in FIG. 8 can be flat, but such an antenna can be tuned to a dome-like surface or other non-planar surface.
[0106]
The present invention can be effectively applied to a plasma processing apparatus such as an etching apparatus. The present invention can also be applied to an etching apparatus, for example, a plasma processing apparatus other than a film forming apparatus or an ashing apparatus. The present invention can also be applied to a plasma processing apparatus for an object to be processed other than a semiconductor wafer, for example, an LCD glass substrate. Additional advantages and modifications will readily occur to those skilled in the art. Accordingly, the present invention in its broad aspects is not limited to the specific embodiments illustrated and described herein and described herein. Accordingly, various modifications can be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.
[Brief description of the drawings]
FIG. 1A is a schematic diagram illustrating a plasma etching system according to a preferred embodiment of the present invention.
FIG. 1B is a schematic diagram illustrating a plasma etching system according to a modification of the embodiment of the present invention.
FIG. 1C is a schematic diagram illustrating a plasma etching system according to a modification of the embodiment of the present invention.
FIG. 2A shows a schematic diagram of a branch RF antenna according to a preferred embodiment of the present invention.
FIG. 2B shows a schematic diagram of a branch RF antenna according to a variation of the embodiment of the present invention.
FIG. 3 shows a simplified diagram of a second type of branched RF antenna according to a variation of the embodiment of the present invention.
FIG. 4 shows a simplified diagram of a third type of branch RF antenna according to a variation of the embodiment of the present invention.
FIG. 5 shows a simplified diagram of a fourth type of branched RF antenna according to a variation of the embodiment of the present invention.
FIG. 6 shows a simplified diagram of an alternative configuration for a fourth type of branch RF antenna according to a variation of an embodiment of the present invention.
FIG. 7 shows a simplified diagram of a first type of branch according to a preferred embodiment of the present invention.
FIG. 8 shows a simplified diagram of a fifth type of branched RF antenna according to a variation of the embodiment of the present invention.
[Explanation of symbols]
100 ... Plasma processing system
102 ... Airtight processing chamber
104 ... Process container
106 ... Upper plate
108 ... Earth wire
110: Branch RF antenna
112 ... Matching device
113 ... Transmission line
114 ... RF power supply
115 ... Insulating layer
116 ... Susceptor
117... Chuck electrode
122 ... Bellows
123 ... mounting table
124... Second matching network
133: Gas supply line
134 ... Gas generating source device
136 ... Exhaust pump
140 ... Faraday shield

Claims (44)

A plasma processing system for performing plasma processing on an object to be processed,
A processing chamber;
A gas supply system for supplying a processing gas to the processing chamber;
An exhaust system for exhausting the processing chamber and performing pressure control;
A susceptor disposed in the processing chamber and having a mounting surface for supporting the object to be processed;
An inductively coupled plasma (ICP) source,
The ICP generation source includes a branch RF antenna and an RF generation source that generate plasma in the processing chamber during the plasma processing,
The branch RF antenna includes a plurality of major branches extending radially outward and a plurality of minor branches branching from the main branch, and each of the main branches includes a plurality of individual branches. A plasma processing system in which the individual branches travel in the same direction from a central area of the branch RF antenna to a branch point and are individually divided in different directions at the branch point to form the sub-branch.   The plasma processing system of claim 1, wherein the ICP source further comprises a matching network coupled to the RF source and the branch RF antenna.   The plasma processing system of claim 1, wherein a first end of a sub-branch is coupled to a main branch, and a second end of the sub-branch is coupled to another sub-branch.   The plasma processing system of claim 1, wherein at least one main branch includes a branch point and at least two sub-branches are coupled to each branch point.   The plasma processing system according to claim 4, wherein at least one main branch has a linear shape and at least one sub-branch has a linear shape.   The plasma processing system according to claim 4, wherein at least one main branch has a curved shape and at least one sub-branch has a linear shape.   The plasma processing system according to claim 4, wherein at least one main branch has a linear shape and at least one sub-branch has a curved shape.   The plasma processing system according to claim 4, wherein at least one main branch has a curved shape and at least one sub-branch has a curved shape.   The plasma processing system according to claim 1, wherein the plurality of main branches are on the same plane. The plasma processing system according to claim 1 , wherein the plurality of sub-branches are on the same plane.   The plasma processing system according to claim 1, wherein the plurality of main branches and the plurality of sub branches are on the same plane.   The plasma processing system according to claim 1, wherein the plurality of main branches are on non-coplanar surfaces.   The plasma processing system according to claim 1, wherein the plurality of sub-branches are on non-coplanar surfaces.   The plasma processing system according to claim 1, wherein the plurality of main branches and the plurality of sub branches are on a non-coplanar surface.   The branch RF antenna further includes a central feed element coupled to the RF source, and the at least one main branch is coupled to the central feed element and at least one sub-branch is grounded. 4. The plasma processing system according to 4.   The branch RF antenna further includes a grounded central feed element, and the at least one main branch is coupled to the central feed element and at least one sub-branch is coupled to the RF source. The plasma processing system according to claim 4.   The branch RF antenna further includes a central feed element coupled to the RF source, and the at least one main branch is coupled to the central feed element, and the at least one sub-branch is through a capacitor. The plasma processing system according to claim 4, which is grounded. A second RF source;
A first main branch is coupled to the RF source and a second main branch is coupled to the second RF source;
The first main branch includes a first branch point; the second main branch includes a second branch point; at least two sub-branches are coupled to the first branch point; and at least two The plasma processing system of claim 1, wherein a sub-branch is coupled to the second branch point.   The plasma processing system according to claim 1, wherein the main branch includes a plurality of the individual branches that are electromagnetically coupled to each other.   The plasma processing system according to claim 1, wherein the main branch comprises a plurality of the individual branches that are electrically coupled to each other.   The RF branch antenna includes a plurality of elements, each element including a main branch and at least two sub-branches coupled to the main branch, wherein the plurality of elements provide equal electrical loads. Plasma processing system.   The RF branch antenna includes a plurality of elements, each element including a main branch and at least two sub-branches coupled to the main branch, wherein the plurality of elements supply different electrical loads. Plasma processing system.   The plasma processing system of claim 1, wherein the RF branch antenna further comprises a central feed element adapted to independently provide RF power to at least two main branches. The plasma processing system according to claim 1, wherein the plurality of main branches and the plurality of sub branches include cooling passages.   The plasma processing system of claim 1, wherein at least one sub-branch has a first end coupled to the RF source and a second end grounded.   The plasma processing system of claim 1, wherein the at least one sub-branch has a first end coupled to the main branch and a second end grounded.   The plasma processing system according to claim 4, wherein a coupling angle between the main branch and the sub branch is smaller than 90 °.   The plasma processing system according to claim 4, wherein the coupling angle between the main branch and the sub-branch is equal to 90 °.   The plasma processing system according to claim 4, wherein a coupling angle between the main branch and the sub-branch is larger than 90 °.   The plasma processing system of claim 1, wherein the ICP source further includes a Faraday shield located between the branch RF antenna and the plasma.   The plasma processing system of claim 1, further comprising a dielectric window between the branch RF antenna and the plasma. The branch RF Antenna The plasma processing system of claim 1, wherein formed on at least one Tan Taira of the surface. The branch RF antenna, a plasma processing system according to claim 1, wherein formed on at least one song plane.   The plasma processing system of claim 1, further comprising a second RF source coupled to the susceptor.   The plasma processing system of claim 1, further comprising a controller coupled to the ICP source. A plasma processing system for performing plasma processing on an object to be processed,
A processing chamber containing plasma;
An exhaust system for exhausting the processing chamber and performing pressure control;
A susceptor disposed in the processing chamber and having a mounting surface for supporting the object to be processed;
An RF electric field for exciting and ionizing the processing gas in the processing chamber is generated to convert the processing gas into the plasma, and a plurality of main branches extending radially outward from a central feed element and the main branches Including a plurality of sub-branches, each main branch comprising a plurality of individual branches, wherein the individual branches are the same from the central area of the branch RF antenna to a branch point to form the sub-branches A branch RF antenna that travels in the direction and is individually divided into different directions at the branch point;
An RF power source coupled to the central feed element and supplying RF power to the branch RF antenna;
A dielectric window disposed between the branch RF antenna and the plasma;
A Faraday shield disposed between the branch RF antenna and the plasma;
A gas supply system coupled to the Faraday shield;
And a plasma processing system for supplying the processing gas to the processing chamber. A plasma processing system for performing plasma processing on an object to be processed,
A processing chamber;
A gas supply system for supplying a processing gas to the processing chamber;
An exhaust system for exhausting the processing chamber and controlling the pressure;
A susceptor disposed in the processing chamber and having a mounting surface for supporting the object to be processed;
An inductively coupled plasma (ICP) source,
The ICP source includes a branch RF antenna and an RF source that generate plasma in the processing chamber during the plasma processing;
The branch RF antenna includes a plurality of main branches and a plurality of minor branches branched from the main branches, and each of the main branches is composed of a plurality of individual branches to form the sub branches. In addition, the plasma processing system includes a plurality of sub-branches arranged in a pattern in which the individual branches proceed in the same direction from the central area of the branch RF antenna to the branch point and are individually divided in different directions at the branch point.   38. The plasma processing system of claim 37, wherein the pattern includes at least one main branch extending radially from a central feed element to a branch point and at least two sub-branches extending from the branch point.   39. The plasma processing system of claim 38, wherein the main branch extends linearly from the central feed element to the branch point and the sub-branch extends linearly from the branch point to the end.   39. The plasma processing system of claim 38, wherein a main branch extends linearly from the central feed element to the branch point and a sub-branch extends from the branch point to the end in a curve.   39. The plasma processing system of claim 38, wherein the main branch extends in a curved manner from the central feed element to the branch point and the sub-branch extends in a straight line from the branch point to the end.   39. The plasma processing system of claim 38, wherein a main branch extends in a curve from the central feed element to the branch point and a sub-branch extends in a curve from the branch point to the end.   The pattern includes at least one main branch that spirals from a central feed element to a branch point and at least two sub-branches that spiral from the first end to a second end around the central feed element. 38. The plasma processing system according to claim 37. A plasma processing system for performing plasma processing on an object to be processed,
A processing chamber;
A gas supply system for supplying a processing gas in the processing chamber;
An exhaust system for exhausting the processing chamber and controlling the pressure;
A susceptor disposed in the processing chamber and having a mounting surface for supporting the object to be processed;
An inductively coupled plasma (ICP) source,
The ICP source includes a branch RF antenna and an RF source that generate plasma in the processing chamber during the plasma processing;
The branch RF antenna includes a plurality of elements, and each element includes a main branch and a plurality of sub branches coupled to the main branch, and each of the main branches includes a plurality of individual branches, A plasma processing system in which the individual branches travel in the same direction from a central area of the branch RF antenna to a branch point and are individually divided in different directions at the branch point to form branches.

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