Plasma processing equipment
The plasma processing apparatus addresses abnormal discharges through a resonator design with optimized impedance matching and wave absorption, ensuring stable plasma processing by instantly stopping and preventing damage.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- TOKYO ELECTRON LTD
- Filing Date
- 2024-11-27
- Publication Date
- 2026-06-08
AI Technical Summary
Existing plasma processing apparatuses suffer from abnormal discharge, which can cause damage and disrupt the plasma processing operation.
The plasma processing apparatus includes a resonator with a specific waveguide configuration and a reflected wave absorber, where the distance between the power supply and the resonator's first end is set to suppress abnormal discharge by optimizing impedance matching and using a circulator or isolator to absorb reflected waves.
This configuration effectively suppresses abnormal discharges, minimizing damage and ensuring stable plasma processing by instantly stopping abnormal discharges and returning to normal operation.
Smart Images
Figure 2026092911000001_ABST
Abstract
Description
Technical Field
[0001] Exemplary embodiments of the present disclosure relate to a plasma processing apparatus.
Background Art
[0002] In plasma processing of a substrate, a plasma processing apparatus is used. One type of plasma processing apparatus includes a chamber, a high-frequency power source, a resonator, an introduction part, and a matcher. The high-frequency power source is coupled to the resonator. Electromagnetic waves from the resonator are supplied into the chamber from the introduction part. The matcher is connected between the high-frequency power source and the resonator. Such a plasma processing apparatus is described in Patent Document 1 below.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] The present disclosure provides a technique for suppressing the influence of abnormal discharge in a plasma processing apparatus.
Means for Solving the Problems
[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, an introduction section, a high-frequency power supply, a high-frequency supply line, a resonator, and a reflected wave absorber. The introduction section is positioned to introduce electromagnetic waves into a plasma generation region within the chamber. The high-frequency supply line is electrically connected to the high-frequency power supply. The resonator has a feed section, a first end, a second end, and a waveguide. The feed section is the entry point for electromagnetic waves in the resonator and is connected to the high-frequency supply line. The waveguide extends between the first and second ends for resonating electromagnetic waves between them and is electromagnetically coupled to the introduction section. A reflected wave absorber is installed on the high-frequency supply line. The distance between the feed section and the first end along the direction of electromagnetic wave propagation is longer than the distance along the direction of propagation between the first end and the point in the resonator where the impedance viewed from there towards the load side during plasma excitation is equal to the characteristic impedance of the high-frequency supply line. [Effects of the Invention]
[0006] According to one exemplary embodiment, it is possible to suppress the effects of abnormal discharge in the plasma processing device. [Brief explanation of the drawing]
[0007] [Figure 1] This figure shows a plasma processing apparatus according to one exemplary embodiment. [Figure 2] This figure shows the lower part of the resonator of a plasma processing apparatus according to one exemplary embodiment. [Figure 3] Figure 3 shows an example of the relationship between the position in the propagation direction within the resonator and the return loss. [Figure 4] Figure 4 shows a plasma processing apparatus according to another exemplary embodiment. [Modes for carrying out the invention]
[0008] Various exemplary embodiments will be described in detail below with reference to the drawings. In each drawing, the same or corresponding parts will be denoted by the same reference numerals.
[0009] Figure 1 shows a plasma processing apparatus according to one exemplary embodiment. The plasma processing apparatus 1 shown in Figure 1 comprises a chamber 10, a substrate support section 12, an introduction section 16, a resonator 20, and a high-frequency power supply 24.
[0010] Chamber 10 provides a processing space 10s within it. In the plasma processing apparatus 1, the substrate W is processed in the processing space 10s. Chamber 10 is made of a metal such as aluminum and is grounded. Chamber 10 has a side wall 10a which is open at its upper end. Chamber 10 and side wall 10a may have a substantially cylindrical shape. The processing space 10s is provided inside the side wall 10a. The central axis of each of chamber 10, side wall 10a, and processing space 10s is axis AX. Chamber 10 may have a corrosion-resistant film on its surface. The corrosion-resistant film may be a ceramic film containing yttrium oxide, yttrium fluoride oxide, yttrium fluoride, yttrium oxide, or yttrium fluoride, etc.
[0011] The bottom of the chamber 10 provides an exhaust port 10e. An exhaust system is connected to the exhaust port 10e. The exhaust system may include a vacuum pump such as a dry pump and / or a turbomolecular pump and an automatic pressure control valve.
[0012] The substrate support portion 12 is located within the processing space 10s. The substrate support portion 12 is configured to support the substrate W placed on its upper surface in a substantially horizontal position. The substrate support portion 12 has a substantially disc shape. The central axis of the substrate support portion 12 is axis AX.
[0013] In one embodiment, the plasma processing apparatus 1 may further include an upper electrode 14. The upper electrode 14 is provided above the substrate support portion 12 via a processing space 10s. The upper electrode 14 is formed from a conductor such as a metal (e.g., aluminum) and has a substantially disc shape. The central axis of the upper electrode 14 is axis AX. The upper electrode 14, together with the shower plate 22 described later, constitutes an excitation electrode.
[0014] The introduction section 16 is provided to emit electromagnetic waves into the plasma generation region. In the plasma processing apparatus 1, the plasma generation region is the space within the processing space 10s and directly below the excitation electrode, i.e., directly below the shower plate 22. In the plasma processing apparatus 1, the electromagnetic waves emitted from the introduction section 16 into the plasma generation region excite the gas in the plasma generation region, thereby generating plasma. The electromagnetic waves emitted from the introduction section 16 into the plasma generation region may be high-frequency waves such as VHF or UHF waves. The introduction section 16 is formed from a dielectric material such as quartz, aluminum nitride, or aluminum oxide. In one embodiment, the introduction section 16 is provided at the lateral end of the processing space 10s and extends circumferentially around the axis AX. The introduction section 16 may have a ring shape.
[0015] The resonator 20 includes a power supply section 20p and a waveguide 20w. The power supply section 20p is the electromagnetic wave inlet for the waveguide 20w of the resonator 20. The electromagnetic wave is generated based on high-frequency power generated by a high-frequency power supply 24. The high-frequency power supply 24 may be configured to change the frequency of the high-frequency power it outputs. The high-frequency power supply 24 and the power supply section 20p are electrically connected via a high-frequency supply line 40. The electromagnetic wave is input to the power supply section 20p of the resonator 20 via the high-frequency supply line 40. The resonator 20 resonates the electromagnetic wave input to the power supply section 20p within the waveguide 20w and propagates it to the introduction section 16. The electromagnetic wave is introduced from the introduction section 16 into the plasma generation region. In one embodiment, the resonator 20 may be located above the chamber 10 and on the upper electrode 14.
[0016] The high-frequency supply line 40 may include a coaxial connector 40c, which is a coaxial line. The coaxial connector 40c includes an inner conductor 40i and an outer conductor 40o. The outer conductor 40o has a cylindrical shape and surrounds the inner conductor 40i. The inner conductor 40i and the outer conductor 40o extend coaxially. The lower end of the inner conductor 40i is electrically connected to the power supply unit 20p. In one embodiment, the lower end of the inner conductor 40i is electrically connected to the wall of the resonator 20 that defines the upper part 20a from below. The lower end of the inner conductor 40i may also be electrically connected to the power supply unit 20p via an elastic body (e.g., a spring member) formed from a conductor (not shown). The outer conductor 40o is also electrically connected to the wall of the resonator 20 that defines the upper part 20a from above.
[0017] The plasma processing apparatus 1 further includes a circulator 25. The circulator 25 includes a first port 251, a second port 252, and a third port 253. The circulator 25 outputs high-frequency power (forward wave, incident wave) received at the first port 251 from the second port 252, and outputs high-frequency power (reflected wave) received at the second port 252 from the third port 253. A high-frequency power supply 24 is connected to the first port 251. The second port 252 is connected to the power supply unit 20p via a high-frequency supply line 40. A load 27 is connected to the third port 253. According to the plasma processing apparatus 1, the reflected wave of high-frequency power is returned to the load 27 by the circulator 25. Therefore, the return of the reflected wave to the high-frequency power supply 24 is suppressed. The plasma processing apparatus 1 may also include an isolator instead of the circulator 25, which outputs high-frequency power from the high-frequency power supply 24 to the power supply unit 20p via the high-frequency supply line 40 and outputs the reflected wave of the high-frequency power to the load 27.
[0018] In one embodiment, the plasma processing apparatus 1 may further include a shower plate 22. The shower plate 22 may be formed of a metal such as aluminum. The introduction part 16 extends so as to surround the shower plate 22. The introduction part 16 and the shower plate 22 are arranged so as to close the opening at the upper end of the chamber 10. The shower plate 22 provides a plurality of gas holes 22h. The plurality of gas holes 22h extend in the thickness direction (vertical direction) of the shower plate 22 and penetrate the shower plate 22.
[0019] The shower plate 22 is provided under the upper electrode 14. The shower plate 22 extends over the plasma generation region described above. The shower plate 22 and the upper electrode 14 define a gas diffusion space 14d therebetween. The central axis of the gas diffusion space 14d may be the axis AX. A plurality of gas holes 22h of the shower plate 22 are connected to the gas diffusion space 14d. Further, the upper electrode 14 provides an inlet 14h. The inlet 14h may extend on the axis AX. The inlet 14h is connected to the gas diffusion space 14d. A gas supply part 26 is connected to the gas diffusion space 14d. The gas output from the gas supply part 26 is supplied to the processing space 10s through the inlet 14h, the gas diffusion space 14d, and the plurality of gas holes 22h. [[ID=?]] [[ID=?]]
[0020] [[ID=?]] Hereinafter, reference will be made to FIG. 2 together with FIG. 1. FIG. 2 is a diagram showing the lower part of the resonator in a plasma processing apparatus according to one exemplary embodiment. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. The waveguide 20w of the resonator 20 may provide a cavity surrounded by walls. The walls of the waveguide 20w are formed of a material such as metal. The walls of the waveguide 20w may be formed of an aluminum alloy, copper, nickel, stainless steel, etc., and may be coated with a low-resistance material such as silver, gold, or rhodium.
[0021] The resonator 20 includes a first end 201 and a second end 202. The first end 201 and the second end 202 constitute one end and the other end of the waveguide 20w of the resonator 20. The waveguide 20w extends between the first end 201 and the second end 202 and is electromagnetically coupled to the introduction part 16.
[0022] In one embodiment, the wall of the resonator 20 may include an inner peripheral portion 20i and an outer peripheral portion 20o. The inner peripheral portion 20i extends around the axis AX which is its central axis and has a substantially cylindrical shape. The outer peripheral portion 20o extends coaxially with the inner peripheral portion 20i around the axis AX. The outer peripheral portion 20o may have a substantially cylindrical shape.
[0023] The waveguide 20w may have a layer structure that folds back alternately between the inner peripheral portion 20i and the outer peripheral portion 20o. The wall of the waveguide 20w may include a plurality of walls that extend in the radial and circumferential directions between adjacent layers of the layer structure and between the inner peripheral portion 20i and the outer peripheral portion 20o. The plurality of walls may be annular plates.
[0024] Also, the waveguide 20w may include an upper portion 20a that constitutes the uppermost layer of the layer structure and a lower portion 20b that constitutes the lowermost layer of the layer structure. Also, the layer structure may include an intermediate portion 20c between the upper portion 20a and the lower portion 20b. In this embodiment, the upper portion 20a may provide the first end 201, that is, the upper end, of the waveguide 20w at the outer peripheral portion 20o. In this case, the first end 201 of the waveguide 20w extends along the circumferential direction around the axis AX. Also, the lower portion 20b may provide the second end 202, that is, the lower end, of the waveguide 20w at the outer peripheral portion 20o. In this case, the second end 202 of the waveguide 20w extends along the circumferential direction around the axis AX.
[0025] The resonator 20 provides a plurality of gaps 20g near or along the second end 202. The plurality of gaps 20g are arranged along the circumferential direction around the axis AX. The electromagnetic wave resonated in the resonator 20 propagates electromagnetically to the introduction part 16 through the plurality of gaps 20g.
[0026] In one embodiment, the upper electrode 14 provides a plurality of slots 14s as a plurality of gaps 20g and includes a plurality of beams 14b. The plurality of slots 14s are located above the inlet 16. The plurality of slots 14s electromagnetically couple the waveguide 20w and the inlet 16 to each other. The plurality of slots 14s penetrate the upper electrode 14 along its thickness direction (vertical direction) and extend long in the circumferential direction. The plurality of slots 14s are spaced apart from each other and arranged along the circumferential direction around the axis AX. The plurality of slots 14s may be arranged at equal intervals. The plurality of beams 14b are arranged alternately with the plurality of slots 14s along the circumferential direction around the axis AX. The plurality of beams 14b connect the inner and outer portions of the upper electrode 14 to each other.
[0027] In the plasma processing apparatus 1, electromagnetic wave resonance occurs between the first end 201 and the second end 202 of the resonator 20. The electromagnetic waves that resonate in the resonator 20 are supplied to the introduction section 16 through multiple gaps 20g, i.e., multiple slots 14s. The electromagnetic waves supplied to the introduction section 16 are emitted from the introduction section 16 into the plasma generation region.
[0028] As shown in Figure 1, in the plasma processing apparatus 1, the distance between the power supply unit 20p and the first end 201 along the direction of electromagnetic wave propagation (radial direction or opposite direction) is longer than the distance L50. The distance L50 is the distance along the propagation direction between the point in the resonator 20 where the impedance viewed from there towards the load side during plasma excitation is equal to the characteristic impedance of the high-frequency supply line 40 and the first end 201.
[0029] Figure 3 shows an example of the relationship between the position in the propagation direction within the resonator and the return loss. In Figure 3, graph G1 shows the return loss during normal discharge, and graph G2 shows the return loss during abnormal discharge. In Figure 3, L50 on the horizontal axis indicates the position at which the distance from the first end 201 is L50, and position Pi on the horizontal axis indicates the installation position in the plasma processing apparatus 1. As shown in Figure 3 and as described above, in the plasma processing apparatus 1, the distance between the power supply unit 20p (position Pi) and the first end 201 along the propagation direction is longer than the distance L50.
[0030] As shown in graph G1, during normal discharge, there is almost no reflection at a distance L50 from the first end 201, and a certain return loss occurs when the power supply unit 20p is installed at position Pi. In the illustrated example, the return loss when the power supply unit 20p is installed at position Pi is about 16 dB, and the reflected wave power is about 2.5% of the incident wave power.
[0031] As shown in graph G2, when an abnormal discharge occurs, the return loss is greater when the power supply unit 20p is located at position Pi compared to when it is located at a distance L50 from the first end 201. In the illustrated example, the reflected wave power is about 16% of the incident wave power at a distance L50 from the first end 201. In contrast, in the illustrated example, the return loss is small, at 5 dB, when the power supply unit 20p is located at position Pi, and the reflected wave power is larger, at about 32% of the incident wave power.
[0032] As a result, the plasma processing apparatus 1, when an abnormal discharge occurs, increases the reflected wave power to self-match and reduce the power supplied to the plasma, thereby instantly stopping the abnormal discharge. In other words, if the plasma density is low relative to the plasma density at the top of the processing vessel (e.g., inside the chamber 10) under the desired plasma excitation conditions, the radial position where the impedance from the resonator input (e.g., the power supply unit 20p) to the load side is 50Ω becomes shorter than L50. Conversely, if it is high, it becomes longer than L50.
[0033] On the other hand, if an abnormal discharge occurs in the processing vessel, high-frequency power is consumed at the abnormal discharge generation site, resulting in a decrease in the average plasma density at the top of the processing vessel. The propagation direction position of the resonator input where the impedance on the load side is 50Ω becomes shorter than L50. In the plasma processing apparatus 1, the propagation direction position of the resonator input is originally set to be longer than L50, so when an abnormal discharge occurs, the return loss decreases and the power supplied to the plasma decreases significantly due to self-matching.
[0034] The frequency matching function built into the high-frequency power supply 24 optimizes the frequency to minimize reflections. However, if the radial position of the resonator input is deviated from the matching position, reflections cannot be suppressed, and a state of high reflections is maintained. As a result, the abnormal discharge disappears instantaneously. Once the abnormal discharge disappears, the system automatically returns to the normal plasma excitation state. Thus, the plasma processing device 1 can instantly stop abnormal discharges when they occur and instantly return to the original state after the abnormal discharge has stopped. Therefore, damage caused by abnormal discharges can be minimized. As a result, the plasma processing device 1 can suppress the effects of abnormal discharges.
[0035] In the above example, the distance between the power supply unit 20p and the first end 201 along the propagation direction was such that the reflected wave power of the high-frequency power from the high-frequency power supply 24 was approximately 2.5% of the incident wave power. However, in another example, the distance between the power supply unit 20p and the first end 201 along the propagation direction may be set so that the reflected wave power of the high-frequency power from the high-frequency power supply 24 is 5% or less of the incident wave power. In yet another example, the distance between the power supply unit 20p and the first end 201 along the propagation direction may be set so that the reflected wave power of the high-frequency power from the high-frequency power supply 24 is 10% or less of the incident wave power.
[0036] Furthermore, in the plasma processing apparatus 1, since the distance between the power supply unit 20p and the first end 201 is longer than the distance L50, a matching state is not achieved even at the frequency where reflection is minimized. However, the plasma processing apparatus 1 includes a circulator 25 or isolator that includes a first port 251 connected to the high-frequency power supply 24, a second port 252 connected to the high-frequency supply line 40, and a third port 253 connected to the load 27. Therefore, reflected waves can be absorbed by the load 27.
[0037] Hereinafter, a plasma processing apparatus according to another exemplary embodiment will be described with reference to Figure 4. Figure 4 is a diagram showing a plasma processing apparatus according to another exemplary embodiment.Hereinafter, the plasma processing apparatus 1A shown in Figure 4 will be described in terms of differences from the plasma processing apparatus 1.The plasma processing apparatus 1A further comprises a reactance variable circuit 50.The reactance variable circuit 50 is provided in the high-frequency supply line 40 between the coaxial connector 40c and the second port 252 of the circulator 25.
[0038] In the plasma processing apparatus 1A (or plasma processing apparatus 1), the position of the power supply unit 20p is set so that, for example, a few percent of reflection occurs during normal discharge in order to suppress abnormal discharge. However, when the plasma excitation conditions change, both the position of the resonator input unit (e.g., the power supply unit 20p) where there is no reflection (e.g., at a distance L50 from the first end 201) and the position of the resonator input unit where a few percent of reflection occurs change. In response to this, the plasma processing apparatus 1A is provided with a reactance variable circuit 50 between the resonator input unit and the circulator 25. The reactance of the reactance variable circuit 50 is adjusted so that a few percent of reflection occurs during normal discharge according to the plasma excitation conditions. As a result, abnormal discharge can be suppressed without changing the position of the resonator input unit, even when the plasma excitation conditions change.
[0039] Although various exemplary embodiments have been described above, the invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and modifications may be made. Furthermore, it is possible to combine elements from different embodiments to form other embodiments.
[0040] For example, the plasma processing apparatus 1 may include a matching circuit connected between the high-frequency supply line 40 and ground. In this case, the matching circuit can be matched so that, for example, a few percent of reflection occurs during normal discharge, thereby being compatible with the function of reducing the power supplied to the plasma in a self-matching manner by increasing the reflected wave power during abnormal discharge in the plasma processing apparatus 1.
[0041] Herein, various exemplary embodiments included in this disclosure are described in [E1] to [E12] below.
[0042] [E1] Chamber and, An introduction unit arranged to introduce electromagnetic waves into the plasma generation region within the chamber, High-frequency power supply and A high-frequency supply line electrically connected to the aforementioned high-frequency power supply, A resonator having a power supply section which is an entry point for electromagnetic waves and connected to the high-frequency supply line, a first end and a second end for resonating the electromagnetic waves between them, and a waveguide extending between the first end and the second end and electromagnetically coupled to the entry point, A reflected wave absorber installed in the aforementioned high-frequency supply line, Prepare, A plasma processing apparatus wherein the distance between the power supply unit and the first end along the propagation direction of the electromagnetic wave is longer than the distance between the first end and the point in the resonator where the impedance viewed from there towards the load side during plasma excitation is equal to the characteristic impedance of the high-frequency supply line, along the propagation direction.
[0043] [E2] The plasma processing apparatus according to E1, further comprising a circulator or isolator including a first port connected to the high-frequency power supply, a second port connected to the high-frequency supply line, and a third port connected to a load.
[0044] [E3] The plasma processing apparatus according to E1 or E2, wherein the distance between the power supply unit and the first end along the propagation direction is set such that the reflected wave power of the high-frequency power from the high-frequency power supply is 10% or less of the incident wave power of the high-frequency power.
[0045] [E4] The plasma processing apparatus according to any one of E1 to E3, further comprising a reactance variable circuit provided in the high-frequency supply line.
[0046] [E5] The aforementioned resonator is The chamber and the inner circumferential portion extending around the central axis of the resonator, The waveguide has an outer peripheral portion extending around the central axis and a layered structure that alternately folds back between the inner peripheral portion and the outer peripheral portion. Located in the uppermost layer of the aforementioned layer structure, the upper part provides the first end in the outer peripheral portion, A lower part located at the lowest layer of the layer structure, providing the second end in the outer periphery, and providing a plurality of slots along the second end for connecting the waveguide and the introduction portion to each other, A plasma processing apparatus described in any of E1 to E4, including the one described above.
[0047] From the above description, it will be understood that the various embodiments of this disclosure are described herein for illustrative purposes and can be modified in various ways without departing from the scope and spirit of this disclosure. Accordingly, the various embodiments disclosed herein are not intended to limit the scope and spirit, and the true scope and spirit are shown by the appended claims. [Explanation of Symbols]
[0048] 1,1A...Plasma processing device, 10...Chamber, 12...Substrate support section, 16...Inlet section, 20...Resonator, 20w...Waveguide, 20p...Power supply section, 201...First end, 202...Second end, 24...High-frequency power supply, 25...Circulator, 40...High-frequency supply line, 50...Variable reactance circuit.
Claims
1. Chamber and, An introduction unit arranged to introduce electromagnetic waves into the plasma generation region within the chamber, High-frequency power supply and A high-frequency supply line electrically connected to the aforementioned high-frequency power supply, A resonator having a power supply section which is an entry point for electromagnetic waves and connected to the high-frequency supply line, a first end and a second end for resonating the electromagnetic waves between them, and a waveguide extending between the first end and the second end and electromagnetically coupled to the entry point, A reflected wave absorber installed in the aforementioned high-frequency supply line, Equipped with, The distance between the power supply unit and the first end along the propagation direction of the electromagnetic wave is longer than the distance between the point in the resonator where the impedance viewed from there towards the load side during plasma excitation is equal to the characteristic impedance of the high-frequency supply line and the first end, along the propagation direction. Plasma processing equipment.
2. The circulator or isolator further includes a first port connected to the high-frequency power supply, a second port connected to the high-frequency supply line, and a third port connected to the load. The plasma processing apparatus according to claim 1.
3. The distance between the power supply unit and the first end along the propagation direction is set such that the reflected wave power of the high-frequency power from the high-frequency power source is 10% or less of the incident wave power of the high-frequency power. The plasma processing apparatus according to claim 1 or 2.
4. The high-frequency supply line further comprises a reactance variable circuit, The plasma processing apparatus according to claim 1 or 2.
5. The aforementioned resonator is, The chamber and the inner circumferential portion extending around the central axis of the resonator, The outer periphery extending around the aforementioned central axis, The waveguide having a layered structure that alternately folds back between the inner and outer circumferential portions, Located in the uppermost layer of the aforementioned layer structure, the upper part provides the first end in the outer peripheral portion, A lower part located at the lowest layer of the layer structure, providing the second end in the outer periphery, and providing a plurality of slots along the second end for connecting the waveguide and the introduction portion to each other, including, The plasma processing apparatus according to claim 1 or 2.