JP2000331996A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing device that makes the unevenness of electric field distribution on a surface of an electrode small so that etching rate distribution is uniform in a plasma process using a high density plasma that can correspond to further fining. SOLUTION: In a plasma processing device 1, a first and second electrodes 21 and 5 that are provided so as to face each other in a chamber are placed, a conductive cylindrical member 61 grounded in close vicinity to the circumference of a load dispatching bar 33 supplying high frequency to the first electrode 21 is provided, and a conductive plate member 62 grounded in a close vicinity to a surface of the first electrode 21 opposite to a surface facing the second electrode 5 is provided. Under a state where a substrate W is supported by one of these electrodes, the plasma of processing gas is formed by forming a high frequency electric field between the first and second electrodes, and plasma processing is performed on the substrate W by this plasma.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a plasma processing apparatus for performing a plasma processing on a substrate such as a semiconductor substrate.

[0002]

2. Description of the Related Art In a semiconductor device manufacturing process, for example, plasma processing such as etching, sputtering, and CVD (chemical vapor deposition) is frequently used on a semiconductor wafer as a substrate to be processed.

Various types of plasma processing apparatuses have been used for performing such plasma processing, and among them, a capacitively coupled parallel plate plasma processing apparatus is mainly used.

A capacitively coupled parallel plate plasma processing apparatus is
A pair of parallel plate electrodes (upper and lower electrodes) are placed in the chamber, a processing gas is introduced into the chamber, and a high frequency is applied to one of the electrodes to form a high-frequency electric field between the electrodes. A plasma of a processing gas is formed to perform a plasma processing on the semiconductor wafer.

When a film on a semiconductor wafer, for example, an oxide film, is etched by such a capacitively coupled parallel plate plasma processing apparatus, the pressure inside the chamber is set to a medium pressure to form a medium-density plasma, thereby obtaining an optimum radical. Control is possible, whereby an appropriate plasma state can be obtained, and etching with high selectivity, high stability and high reproducibility is realized.

However, in recent years, design rules in the USLI have been increasingly miniaturized, and a higher aspect ratio of the hole shape has been demanded, and the conventional conditions for etching an oxide film and the like are not always sufficient. It is getting.

Therefore, attempts have been made to increase the frequency of the high-frequency power to be applied and to form high-density plasma while maintaining a good plasma dissociation state. As a result, appropriate plasma can be formed under lower pressure conditions, so that it is possible to appropriately cope with further miniaturization of design rules.

[0008]

According to the results of the study by the present inventors, when the frequency of the high-frequency power to be applied is increased and the plasma density is increased,
It has been found that the following new problems arise.

Conventionally, power has been supplied to the upper electrode via a power supply rod, and the periphery of the power supply rod is covered with a box having substantially the same size as the chamber to shield electromagnetic waves. However, since the inductance of the feed rod is very large, if the frequency of the high-frequency power supplied to the upper electrode is increased to increase the plasma density, harmonics of the reflected wave from the plasma are reflected due to the inductance component of the feed rod. Then, the light is reflected throughout the box in which the power supply rod is installed, and the reflected harmonic returns to the upper electrode surface in contact with the plasma. When the electrode diameter is φ250 to φ300 mm, a standing wave is likely to be generated on the electrode surface by such a harmonic, and when such a standing wave is generated, the electric field distribution on the electrode surface becomes uneven.

The power supply rod is provided at the center of the back surface of the upper electrode. However, if the applied frequency is increased to form high-density plasma, the high-frequency current flows only on the surface of the electrode. The high-frequency power supplied from the power supply rod to the upper electrode passes through the back surface of the electrode to the circumferential direction of the electrode, and is gradually supplied from the circumference toward the center of the plasma contact surface of the electrode. The circumference of the upper electrode is surrounded by an insulator (capacitive component), and the chamber outside the insulator is grounded. For this reason, a standing wave is formed at the plasma contact surface of the upper electrode due to the interference action, and the electric field distribution in the radial direction of the electrode becomes non-uniform.

If the electric field distribution becomes non-uniform as described above, the plasma density becomes non-uniform and the etching rate distribution becomes non-uniform. Therefore, any of the causes of the non-uniform electric field distribution is eliminated to make the etching rate distribution uniform. It is necessary.

However, conventionally, the problem in using such high-density plasma has not always been clearly recognized, and attempts to eliminate the above-described non-uniform electric field distribution have been made sufficiently. It is not at present.

The present invention has been made in view of such circumstances, and it is possible to reduce non-uniformity of electric field distribution on an electrode surface in plasma processing using high-density plasma capable of coping with miniaturization. It is an object of the present invention to provide a plasma processing apparatus capable of making the plasma density uniform.

[0014]

According to a first aspect of the present invention, there is provided, in accordance with a first aspect of the present invention, a chamber in which a substrate to be processed is housed, and a chamber provided opposite to the chamber in the chamber. A first and a second electrode; a high frequency applying means for applying a high frequency to the first electrode; and a high frequency applying means for applying a high frequency to a surface of the first electrode opposite to a surface facing the second electrode. A power supply rod for supplying power, a conductive cylindrical member provided near the power supply rod around the power supply rod and grounded, and a surface of the first electrode facing the second electrode. A conductive plate member provided in proximity to the opposite surface and grounded; exhaust means for maintaining the inside of the chamber at a predetermined reduced pressure; and processing gas introduction means for introducing a processing gas into the chamber And treating the first or second electrode with While being supported substrate, said first
A plasma processing apparatus is provided, wherein a plasma of a processing gas is formed by forming a high-frequency electric field between the second electrodes, and a plasma processing is performed on a substrate to be processed by the plasma.

According to a second aspect of the present invention, a chamber accommodating a substrate to be processed, first and second electrodes provided to face each other in the chamber, A high-frequency applying means for applying a high-frequency, and a power supply rod for supplying high-frequency power from the high-frequency applying means to a position on a surface of the first electrode opposite to a surface facing the second electrode and separated from the center thereof A phase adjusting means arranged at one end thereof connected to the first electrode and the other end thereof grounded to adjust the phase of the voltage and current of the high-frequency power supplied to the first electrode; An exhaust unit that maintains the inside of the chamber at a predetermined reduced pressure state; and a processing gas introduction unit that introduces a processing gas into the chamber, wherein the substrate to be processed is supported by the first or second electrode. , The first and Second plasma of the processing gas by forming a high frequency electric field is formed between the electrodes, the plasma processing apparatus characterized by performing a plasma process on a target substrate is provided by the plasma.

In this case, the phase adjusting means includes a portion of the first electrode opposite to a power supply position of the power supply rod across a center of a surface opposite to a surface facing the second electrode. It is preferable to have the LC circuit provided in the first embodiment.

In each of the above plasma processing apparatuses,
The frequency of the high frequency applied to the first electrode is 27 MHz
Higher is preferred. Further, in each of the above plasma processing apparatuses, the second electrode has a frequency of 100 kHz to 10 Mhz.
It is preferable that the apparatus further includes a high frequency applying means for applying a high frequency of Hz.

According to the first aspect of the present invention, a power supply rod for supplying high-frequency power from high-frequency applying means is provided on the surface of the first electrode opposite to the surface facing the second electrode. A grounded conductive tubular member is provided around the power supply rod and close to the power supply rod, and the second electrode of the first electrode is provided.
Since the conductive plate-shaped member is provided close to the surface opposite to the surface facing the electrode, the equivalent circuit, between the power supply rod and the cylindrical member, and between the first electrode and the plate-shaped member Between the members, a number of capacitors are formed in parallel,
The inductance component of the power supply rod and the inductance component of the surface on the power supply side of the first electrode (the surface opposite to the second electrode) are canceled by the capacitance component of the capacitor, and the impedance is reduced. The inductance of the power supply side surface of the first electrode is reduced. Also,
Since the cylindrical member and the plate member are grounded, the harmonic reflected by the power supply rod falls to the ground through the cylindrical member and the plate member. Therefore, the higher harmonics from the plasma are less likely to be reflected by the feed rod, and the higher harmonics themselves are reduced, so that a standing wave is less likely to be generated at the plasma contact surface of the first electrode. Therefore, the electric field distribution on the plasma contact surface of the first electrode can be made more uniform, and the plasma density can be made uniform.

According to the second aspect of the present invention, on the surface of the first electrode opposite to the surface facing the second electrode, the high-frequency power is supplied from the high-frequency applying means to a position away from the center thereof. And a phase adjusting means for adjusting the phase of the voltage and current of the high-frequency power supplied to the first electrode, so that the plasma contact surface of the first electrode is located on the circumferential side of the electrode. The phases of the voltage and current supplied from the power supply can be made non-uniform on the circumference, and the formation of a standing wave due to interference can be prevented. Therefore, the electric field distribution on the plasma contact surface of the first electrode can be made more uniform, and the plasma density can be made uniform.

[0020]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view schematically showing a plasma processing apparatus according to the first embodiment of the present invention. The plasma processing apparatus 1 is configured as a capacitively-coupled parallel flat plate etching apparatus in which electrode plates are vertically opposed to each other and one side is connected to a power supply for plasma formation.

The plasma etching apparatus 1 has a cylindrical chamber 2 made of aluminum whose surface is anodized (anodized), for example, and the chamber 2 is grounded. A substantially columnar susceptor support 4 for mounting an object to be processed, for example, a semiconductor wafer (hereinafter, referred to as “wafer”) W is provided at the bottom of the chamber 2 via an insulating plate 3 made of ceramic or the like. And the susceptor support 4
Is provided with a susceptor 5 constituting a lower electrode. This susceptor 5 has a high-pass filter (HP
F) 6 is connected.

A coolant chamber 7 is provided inside the susceptor support 4. In the coolant chamber 7, a coolant such as liquid nitrogen is introduced and circulated through a coolant introduction pipe 8. Cold heat is transferred to the wafer W via the susceptor 5, whereby the processing surface of the wafer W is controlled to a desired temperature.

The susceptor 5 is formed in a disk shape having a convex upper central portion, and an electrostatic chuck 11 having substantially the same shape as the wafer W is provided thereon. The electrostatic chuck 11 has an electrode 12 interposed between insulating materials. When a DC voltage of, for example, 1.5 kV is applied from a DC power supply 13 connected to the electrode 12, the electrostatic chuck 11 holds the wafer W by, for example, Coulomb force. Adsorb electrostatically.

The insulating plate 3, the susceptor support 4, the susceptor 5, and the electrostatic chuck 11
A heat transfer medium, for example, H
A gas passage 14 for supplying e-gas or the like is formed, and the cool heat of the susceptor 5 is transmitted to the wafer W via the heat transfer medium, so that the wafer W is maintained at a predetermined temperature.

An annular focus ring 15 is arranged on the upper peripheral edge of the susceptor 5 so as to surround the wafer W mounted on the electrostatic chuck 11. The focus ring 15 is made of a conductive material such as silicon, so that the uniformity of etching is improved.

An upper electrode 21 is provided above the susceptor 5 so as to face the susceptor 5 in parallel. The upper electrode 21 is connected to the chamber 2 via an insulating material 25.
, And constitutes a surface facing the susceptor 5 and has a large number of discharge holes 24, for example, silicon, Si
An electrode plate 23 made of C, amorphous carbon, or conductive high-resistance ceramics, and an electrode support 22 that supports the electrode plate 23 and has a water-cooled structure made of a conductive material, for example, aluminum whose surface is anodized. Have been. The susceptor 5 and the upper electrode 21 are separated from each other by, for example, about 10 to 60 mm.

The electrode support 22 of the upper electrode 21
Is provided with a gas inlet 26, and a gas supply pipe 27 is connected to the gas inlet 26. The gas supply pipe 27 is connected to a processing gas via a valve 28 and a mass flow controller 29. A source 30 is connected. A processing gas for plasma processing, for example, etching is supplied from the processing gas supply source 30.

As the processing gas, various kinds of conventionally used gases can be employed, for example, a fluorocarbon gas (C _x F _y ) or a hydrofluorocarbon gas (C _p
H q _{F r)} a halogen element such as can be suitably used a gas containing a. In addition, rare gases such as Ar and He and N
₂ may be added.

An exhaust pipe 31 is connected to the bottom of the chamber 2, and an exhaust device 35 is connected to the exhaust pipe 31. The exhaust device 35 is provided with a vacuum pump such as a turbo-molecular pump, so that the inside of the chamber 2 can be evacuated to a predetermined reduced pressure atmosphere, for example, a predetermined pressure of 0.01 Pa or less. Further, a gate valve 32 is provided on a side wall of the chamber 2, and the wafer W is transferred to and from an adjacent load lock chamber (not shown) with the gate valve 32 opened. ing.

A first high-frequency power supply 40 is connected to the upper electrode 21 via a matching unit 41. In this case, power is supplied to the center of the upper surface of the upper electrode 21 (that is, the center of the upper surface of the electrode support 22). This is performed by the connected power supply rod 33. The upper electrode 21 has a low-pass filter (LPF) 4
2 are connected. The first high-frequency power supply 40
It has a frequency of 7 MHz or more, and by applying such a high frequency, it is possible to form a high-density plasma in a preferable dissociated state in the chamber 2,
Plasma processing under low pressure conditions becomes possible. In this example,
A high-frequency power supply 40 of 60 MHz is used.

The power supply rod 33 is provided in an electromagnetic wave shielding box 60 having the same diameter as the chamber 2 that is continuous from the chamber 2, thereby shielding electromagnetic waves.
In addition, a conductive tubular member 61 is provided around the power supply rod 33 near the power supply rod 33. On the other hand, a conductive plate member 62 is provided near the upper surface of the electrode support 22. The tubular member 61 and the plate member 62 are electrically connected, and the plate member 62 is electrically connected to the grounded chamber 2. That is, the cylindrical member 6
1 and the plate member 62 are grounded via the chamber 2. The tubular member 61 can reduce the inductance of the power supply rod 33 and lower harmonics to ground, as described later. In addition, the plate-shaped member 62 can reduce the inductance of the electrode 21 and lower harmonics to ground.

A second high-frequency power supply 50 is connected to the susceptor 5 serving as a lower electrode, and a matching unit 51 is interposed in the power supply line. The second high-frequency power supply 50 has a frequency in the range of, for example, 100 kHz to 10 MHz. By applying a frequency in such a range, the second high-frequency power supply 50 can be appropriately applied without damaging the wafer W to be processed. Ionic action. In this example, a second high-frequency power supply 50 of 2 MHz is used.

Next, the processing operation in the plasma processing apparatus 1 configured as described above will be described by taking as an example a case where a predetermined film formed on the wafer W is etched. First, the wafer W to be processed is placed in the gate valve 3.
After the opening 2 is opened, it is carried into the chamber 2 from a load lock chamber (not shown) and placed on the electrostatic chuck 11. The wafer W is electrostatically attracted onto the electrostatic chuck 11 by applying a DC voltage from the high-voltage DC power supply 13. Next, the gate valve 32 is closed,
The inside of the chamber 2 is evacuated to a predetermined degree of vacuum by the exhaust device 35.

Thereafter, the valve 28 is opened, and the processing gas is supplied from the processing gas supply source 30 to the mass flow controller 2.
9, while the flow rate is adjusted, the processing gas supply pipe 2
7. The gas is introduced into the upper electrode 21 through the gas introduction port 26, and is further uniformly discharged through the discharge hole 24 of the electrode plate 23 to the wafer W as shown by an arrow in FIG.
The pressure in the chamber 2 is maintained at a predetermined value.

After that, a high frequency of 27 MHz or more, for example, 60 MHz, is applied to the upper electrode 21 from the first high frequency power supply 40. As a result, a high-frequency electric field is generated between the upper electrode 21 and the susceptor 5 as a lower electrode, and the processing gas is dissociated into plasma, and this plasma causes
An etching process is performed on the wafer W.

On the other hand, from the second high-frequency power supply 50, 10
A high frequency of 0 kHz to 10 MHz, for example, 2 MHz, is applied to the susceptor 5 as the lower electrode. Thereby, the ions in the plasma are attracted to the susceptor 5 side, and the anisotropy of the etching is enhanced by the ion assist.

As described above, the plasma density can be increased by setting the frequency of the high frequency applied to the upper electrode 21 to be higher than 27 MHz. However, in the conventional upper electrode structure, the higher frequency of the reflected wave from the plasma causes Electrode plate 2
3 by generating a standing wave on the lower surface,
Non-uniformity of the electric field on the lower surface is likely to occur.

That is, since the inductance of the power supply rod 33 is very large, if the frequency of the high-frequency power supplied to the upper electrode 21 is increased in order to increase the plasma density, the harmonics of the reflected wave from the plasma will increase. It is reflected due to the inductance component and further reflected throughout the electromagnetic wave shielding box 60, and the reflected harmonic returns to the surface (lower surface) of the upper electrode 21 which is in contact with the plasma. When the electrode diameter is φ250 to φ300 mm, a standing wave is easily generated on the surface of the electrode 21 by such a harmonic, and when such a standing wave is generated, the electric field distribution on the electrode surface becomes uneven.

On the other hand, by providing a conductive tubular member 61 around the power supply rod 33 close to the power supply rod 33 as in the present embodiment, the equivalent circuit shown in FIG. As shown, a large number of capacitors are formed in parallel between the power supply rod 33 and the cylindrical member 61, and the inductance component of the power supply rod 33 is canceled by the capacitance component of the capacitor, and the impedance is reduced. ,
As a result, the inductance of the feed rod 33 decreases. Further, since the cylindrical member 61 is grounded, the harmonic reflected by the power supply rod 33 passes through the cylindrical member 61 and falls to the ground. Therefore, harmonics from the plasma are less likely to be reflected by the feed rod 33 and the harmonics themselves are reduced, so that standing waves due to the reflection of the harmonics on the plasma contact surface of the electrode plate 23 are less likely to occur. Therefore, the electric field distribution in the plasma contact surface of the electrode plate 23 can be made more uniform, and as a result, the plasma density can be made uniform.

The inductance component on the upper surface of the electrode support 22, that is, the surface on the power supply side of the upper electrode 21 also contributes to the formation of a standing wave due to the reflection of harmonics.
Since the plate-shaped member 62 is formed close to the upper surface of the substrate, a large number of capacitors are formed in parallel between the electrode support 22 and the plate-shaped member 62 as shown in FIG. And the inductance of that part is also reduced by the same principle. Also, the harmonics fall to the ground through the plate member 62. Therefore, the effect of preventing the generation of a standing wave can be further enhanced by the presence of the plate-shaped member 62.

The distance between the cylindrical member 61 and the power supply rod 33 and the distance between the plate member 62 and the electrode support 22 are appropriately determined according to the capacity required for eliminating standing waves. Just set it. For example, when the high-frequency power is 2000 W, 8 mm is used to prevent the breakdown of the atmosphere.
It is necessary. In addition, from the viewpoint of forming the capacitor, it is not necessary to insert a member between the tubular member 61 and the power supply rod 33 and between the plate-like member 62 and the electrode support 22. A radio wave absorber may be inserted to increase the dielectric constant, or a dielectric such as fluororesin (trade name: Teflon) may be inserted to adjust the dielectric constant.

Next, a second embodiment of the present invention will be described. FIG. 4 is a sectional view schematically showing a plasma processing apparatus according to the second embodiment of the present invention. As in the first embodiment, this plasma processing apparatus 1 'is also configured as a capacitive parallel plate etching apparatus in which electrode plates are vertically opposed and one side is connected to a power supply for plasma formation. 1 are basically denoted by the same reference numerals, and description thereof is omitted.

In the present embodiment, unlike the first embodiment, power is supplied to the upper electrode 21 at a position shifted from the center of the upper surface of the upper electrode 21 (ie, the center of the upper surface of the electrode support 22) in the outer peripheral direction. This is performed via the arranged power supply rod 33 '. On the other hand, the power supply rod 33 'on the upper surface of the upper electrode 21
An LC circuit 70 as a phase adjusting means for adjusting the phase of the voltage and current of the high-frequency power supplied to the upper electrode 21 is provided in a portion opposite to the installation position. The LC circuit 70 includes a variable inductance coil 71 and a variable capacitance capacitor 72 connected in series between the upper electrode 21 and the chamber 2. A conductive cylindrical member 61 ′ is provided near the power supply rod 33 ′, and a conductive plate member 62 ′ is provided near the upper surface of the electrode support 22. Tubular member 61 'and plate member 6
2 ′ is electrically connected to the plate-like member 62 ′.
Is electrically connected to the grounded chamber 2.
Other configurations are basically the same as those in FIG.

The plasma processing apparatus 1 'constructed as described above.
In, the etching is performed basically in the same manner as in the plasma processing apparatus 1 according to the first embodiment. In this case, as in the first embodiment, the plasma density can be increased by setting the frequency of the high frequency applied to the upper electrode 21 to 27 MHz or higher. In this case, a standing wave is formed on the plasma contact surface of the upper electrode 21 by an interference action based on the phase difference between the current and the voltage, and the electric field becomes non-uniform.

That is, the electrode plate 23 of the upper electrode 21
Usually, it is made of a conductor or a semiconductor such as Si or SiC, or a conductive high-resistance ceramic, and when a high-frequency current supplied from the high-frequency power supply 40 via the power supply rod 33 increases in frequency, the skin effect causes an Power is supplied only to the extreme surface (the surface depth δ at this time is (2 / ωσ
μ) expressed as ^1/2 . However, when ω = 2πf (f: frequency), σ: electrical conductivity, μ: magnetic permeability), and the power supply rod 33 exists at the center of the upper electrode 21 as in the related art, as shown in FIG. The current is supplied to the surface of the power supply rod 33, the upper surface of the electrode support 22, the side surface of the electrode support 22, and the electrode plate 23.
And reaches the lower surface of the electrode plate 23 which is the plasma contact surface. In this case, since the power supply rod 33 is located at the center of the upper electrode 21, the voltage and current have the same phase everywhere at the edge of the lower surface of the electrode plate 23, and as shown in FIG. The power is gradually supplied from the section in the same phase toward the center. Therefore, the phase difference d / λ between the center and the edge of the electrode plate 23 (λ is the wavelength of the electrode surface wave, d
Is the radius of the electrode). Also, on the electrical equivalent circuit,
The circumferential portion of the upper electrode 21 falls to ground via an insulator (C component) in parallel with the direction in which power is supplied to the plasma, and terminates at a characteristic impedance (50Ω). The electric field strength E ₀ is given by E ₀ = E · cos
(Ωt). Also, the electric field strength E _c at the center of the electrode
Is E _c = E · cos (ωt + d / λ). Here, λ is the wavelength at which the applied frequency and the harmonics due to the reflection from the plasma and the applied frequency are formed via the plasma (wavelength shortening). At this time, since the high frequency power is gradually supplied from the circumferential portion toward the center, the voltage and current from the circumferential side gather at the center of the electrode plate 23. In addition, when the applied frequency increases, the radial inductance of the lower surface of the electrode plate 23 cannot be ignored, and the impedance at the central portion of the lower surface of the electrode plate 23 decreases due to the interference effect due to the phase difference between the voltage and the current. As a result, the electric field intensity at the center of the lower surface of the electrode plate 23 becomes higher than the electric field intensity at the edge. Since the center position is in contact with the plasma, it is an open end in terms of an RF equivalent circuit. Therefore, the wavelength λ = 2d
Is formed. Therefore, the plasma density becomes non-uniform.

Therefore, in the present embodiment, in order to eliminate the standing wave caused by such a cause, high-frequency power is supplied to a position shifted in the circumferential direction from the center of the upper electrode 21 via the feed rod 33 ′. By providing the LC circuit 70 as a phase adjusting means on the upper surface of the upper electrode 21 on the side opposite to the power supply rod 33 ', the phase of the high-frequency voltage and current supplied to the upper electrode 21 becomes uneven on the circumference. To

That is, by supplying high-frequency power to a position shifted in the circumferential direction from the center of the upper electrode 21, the voltage and current paths on the lower surface of the electrode plate 23 are prevented from being concentrated at the center of the electrode plate 23. Then, the phase of the voltage and the current is shifted by adjusting the inductance of the coil 71 and the capacity of the capacitor 72 by using the LC circuit 70 as a phase adjusting means, so that the voltage and the current on the circumference of the electrode plate 23 are shifted. Can be made non-uniform, and the formation of a standing wave due to power supply from the center of the electrode to the lower surface of the electrode plate 23 can be prevented. Therefore, the electric field distribution on the lower surface of the electrode plate 23, that is, the plasma contact surface can be made more uniform, and as a result, the plasma density can be made uniform.

Further, since a cylindrical member 61 'and a plate-like member 62' similar to the cylindrical member 61 and the plate-like member 62 of the first embodiment are provided, similar to the first embodiment, A standing wave due to the reflection of the higher harmonic wave hardly occurs on the plasma contact surface of the electrode plate 23, and the electric field distribution in the plasma contact surface of the electrode plate 23 can be made more uniform.

A certain effect can be obtained if the installation position of the power supply rod 33 'is slightly shifted in the circumferential direction from the center of the upper electrode 21, but for example, the electrode diameter is 25.
In the case of 0 mm, it is preferable to be shifted by 60 mm or more from the center.

In both the first embodiment and the second embodiment, the higher the applied frequency, the more easily a standing wave is formed. This is particularly effective when the applied frequency is 27 MHz or more. There is no effect of the standing wave even at the frequency of, and a certain effect can be obtained by applying the present invention. Further, when the plasma density is not less than 1 × 10 ¹¹ / cm ³ , the above problem is likely to occur, and the present invention is particularly effective in such a case.

The present invention is not limited to the above embodiment, but can be variously modified. For example, in the above embodiment, the high frequency is applied to the upper and lower electrodes, but a high frequency may be applied to only one of the upper and lower electrodes. Further, although the case where the present invention is applied to the upper electrode has been described, it is also possible to apply the present invention to the lower electrode. Further, a case has been described in which a semiconductor wafer is used as a substrate to be processed and the semiconductor wafer is etched, but the present invention is not limited to this, and another substrate such as a liquid crystal display (LCD) substrate may be used as a processing target. The plasma processing is not limited to etching, and may be other processing such as sputtering or CVD.

[0052]

As described above, according to the present invention,
A power supply rod for supplying high-frequency power from high-frequency application means is provided on a surface of the first electrode opposite to a surface facing the second electrode, and a power supply rod is provided around the power supply rod, close to the power supply rod, and grounded. Since a conductive cylindrical member is provided, a large number of capacitors are formed in parallel between the power supply rod and the cylindrical member in an equivalent circuit, and the inductance component of the power supply rod is , The impedance is reduced by the capacitance component, and as a result, the inductance of the power supply rod is reduced. Further, since the cylindrical member is grounded, the harmonic reflected by the power supply rod falls to the ground through the cylindrical member. Further, by forming a grounded conductive plate-like member close to the power supply side surface of the first electrode, the inductance of that portion is also reduced, and harmonics pass through the plate-like member to ground. fall into. Therefore, harmonics from the plasma are less likely to be reflected by the feed rod and the harmonics themselves are reduced, so that standing waves are less likely to be generated at the plasma contact surface of the first electrode. The electric field distribution on the plasma contact surface of the first electrode can be made more uniform, and the plasma density can be made uniform.

According to another aspect of the present invention, on the surface of the first electrode opposite to the surface facing the second electrode, the high-frequency power is supplied from the high-frequency applying means to a position separated from the center thereof. And a phase adjusting means for adjusting the phase of the voltage and current of the high-frequency power supplied to the first electrode, so that the plasma contact surface of the first electrode is located on the circumferential side of the electrode. The phases of the voltage and current supplied from the power supply can be made non-uniform on the circumference, and the formation of a standing wave due to interference can be prevented. Therefore, the electric field distribution on the plasma contact surface of the first electrode can be made more uniform, and the plasma density can be made uniform.

Further, by using the above two inventions together, the plasma density can be made more uniform.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a plasma processing apparatus according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit of a power supply rod and a conductive tubular member in the plasma processing apparatus according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an equivalent circuit of an upper electrode upper surface (electrode support upper surface) and a conductive plate member in the plasma processing apparatus according to the first embodiment of the present invention.

FIG. 4 is a sectional view showing a plasma processing apparatus according to a second embodiment of the present invention.

FIG. 5 is a cross-sectional view schematically showing a high-frequency power supply path in a conventional upper electrode.

FIG. 6 is a bottom view schematically illustrating a high-frequency power supply path in a conventional upper electrode.

[Explanation of symbols]

 1, 1 '; plasma processing apparatus 2, chamber 5, susceptor (second electrode) 6, high-pass filter 21, upper electrode (first electrode) 23, electrode plate 30, processing gas supply source 33, 33', power supply Rod 35; exhaust device 40; first high-frequency power supply 42; low-pass filter 41, 51; matching device 50; second high-frequency power supply 61; cylindrical member 62; plate-like member 70; Semiconductor wafer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G075 BC02 BC04 BC06 CA25 CA47 CA65 EA06 EB42 EC21 FB02 FB04 FC11 4K030 CA04 CA12 FA03 JA18 JA19 KA17 KA19 KA30 KA46 LA15 LA18 5F004 AA01 BA04 BA09 BB11 BB18 BB22 BB23 BB28 BB23 BD04 BD05 DA00 DA01 DA02 DA03 DA15 DA16 DA22 DA23 DA25 5F045 AA08 AC02 AC15 AC16 AC17 BB02 DP03 DQ10 EF05 EH05 EH06 EH14 EH20

Claims (6)

[Claims] A chamber for accommodating a substrate to be processed; first and second electrodes provided in the chamber so as to face each other; a high-frequency application unit for applying a high frequency to the first electrode; A power supply rod for supplying high-frequency power from the high-frequency applying means to a surface of the first electrode opposite to a surface facing the second electrode; and a power supply rod provided around the power supply rod in proximity to the power supply rod; A grounded conductive tubular member, a grounded conductive plate-shaped member provided in close proximity to a surface of the first electrode opposite to a surface facing the second electrode, An exhaust unit for maintaining the inside of the chamber at a predetermined reduced pressure state; and a processing gas introducing unit for introducing a processing gas into the chamber, wherein the first or second electrode supports a substrate to be processed. , A high-frequency electric field between the first and second electrodes A plasma of the processing gas is formed by forming a plasma processing apparatus characterized by performing a plasma process on a target substrate by the plasma. 2. A chamber for accommodating a substrate to be processed, first and second electrodes provided in the chamber so as to face each other, and a high frequency application unit for applying a high frequency to the first electrode; A power supply rod for supplying high-frequency power from the high-frequency application means to a position on the surface of the first electrode opposite to the surface facing the second electrode, the power supply rod being separated from the center thereof; A phase adjusting means connected to the other end and grounded to adjust the phase of the voltage and current of the high-frequency power supplied to the first electrode; and maintaining the inside of the chamber at a predetermined reduced pressure. And a processing gas introducing means for introducing a processing gas into the chamber, wherein the first and second electrodes support a substrate to be processed and the first and second electrodes High frequency in between Forming a plasma of the processing gas by forming a field, the plasma processing apparatus characterized by performing a plasma process on a target substrate by the plasma. 3. The phase adjusting means is provided at a portion of the first electrode opposite to a power supply position with respect to a center of a surface of the first electrode opposite to a surface facing the second electrode. The plasma processing apparatus according to claim 3, further comprising an LC circuit provided. 4. A grounded conductive tubular member provided in the vicinity of the power supply rod near the power supply rod and opposite to a surface of the first electrode facing the second electrode. 4. The plasma processing apparatus according to claim 2, further comprising a conductive plate-shaped member provided near the side surface and grounded. 5. 5. The plasma processing apparatus according to claim 1, wherein the frequency of the high frequency applied to the first electrode is higher than 27 MHz. 6. The frequency of 100 kHz to 10 M is applied to the second electrode.
The plasma processing apparatus according to claim 1, further comprising a high-frequency application unit that applies a high frequency of Hz.