Plasma processing equipment

Abstract

To adjust a load-side impedance electrically connected with a high-frequency power supply.SOLUTION: In a plasma processing apparatus, a processing container is configured to allow plasma processing to be performed. A high-frequency power supply is configured to supply a high-frequency wave to an electrode provided on the processing container. A tube part is provided on the processing container. The tube part includes: a tubular outer conductor; a tubular inner conductor provided inside the outer conductor so as to be separated from the outer conductor; a dielectric body part provided between the outer conductor and the inner conductor; and a short circuit member electrically short-circuiting between the outer conductor and the inner conductor. The tube part is configured to adjust a load-side impedance electrically connected with the high-frequency power supply. The outer conductor is electrically connected with the processing container, which is a grounded conductor. The inner conductor is electrically connected with the electrode.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] An exemplary embodiment of the present disclosure relates to a plasma processing apparatus. [Background technology]

[0002] In plasma processing apparatuses used in the manufacture of electronic devices, a high frequency wave in the very high frequency (VHF) band or ultra high frequency (UHF) band generated by a high frequency power supply is supplied to a processing space. Technologies related to plasma processing apparatuses are disclosed in, for example, Patent Documents 1 to 3. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-35443 [Patent Document 2] Japanese Patent Application Publication No. 2019-106290 [Patent Document 3] International Publication No. 2013 / 89007 Brochure Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for adjusting the impedance on the load side electrically connected to a high frequency power supply. [Means for solving the problem]

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a processing vessel, a high-frequency power supply, and a tube portion. The processing vessel is configured to perform plasma processing. The high-frequency power supply is configured to supply high-frequency waves to an electrode provided in the processing vessel. The tube portion is provided in the processing vessel. The tube portion includes a tubular outer conductor, a tubular inner conductor provided inside the outer conductor and spaced apart from the outer conductor, a dielectric portion provided between the outer conductor and the inner conductor, and a short-circuiting member that electrically shorts the outer conductor and the inner conductor. The tube portion is configured to adjust the impedance of a load side electrically connected to the high-frequency power supply. The outer conductor is electrically connected to a grounded conductor in the processing vessel. The inner conductor is electrically connected to the electrode. [Effects of the Invention]

[0006] According to one exemplary embodiment, the impedance of a load electrically connected to a high frequency power source can be adjusted. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing a configuration of a plasma processing apparatus according to an exemplary embodiment; [Figure 2] 2 is a diagram showing a mathematical expression for the impedance provided by the coaxial filter of the tube section shown in FIG. 1. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0008] Various exemplary embodiments are described below.

[0009] In recent years, advances in semiconductor manufacturing technology have led to demands for higher performance plasma processing equipment. In plasma processing equipment for film formation such as CVD and ALD, high-frequency waves in the VHF to UHF bands are used for plasma excitation to improve productivity by increasing the density of activated species in the gas phase and to reduce damage by lowering the energy of ions incident on the substrate surface.

[0010] The electrodes of a plasma processing apparatus may be connected to pipes for introducing gas, pipes for introducing fluid to maintain a constant electrode temperature, electrical wiring for a heater, electrical wiring for a thermocouple, etc. Insulators, low-pass filters, etc. may be used to prevent high frequency waves from leaking outside the plasma processing apparatus through these pipes and wires, i.e., to electrically insulate the plasma processing apparatus from the outside. When a high high frequency voltage is applied to the insulator, plasma may be generated within the pipes. Discharge within the pipes tends to occur more easily as the plasma excitation frequency increases.

[0011] Meanwhile, the high frequency waves output from the matching box connected to the high frequency power supply propagate through the propagation section within the plasma processing apparatus and are emitted from the high frequency emission section into the processing chamber. At the high frequency emission section, a portion of the high frequency waves is reflected and returns to the matcher, causing standing waves in the propagation section for frequencies in the VHF to UHF bands. As a result, even if the voltage required for plasma ignition is several hundred volts at the high frequency emission section, it may exceed several thousand volts at the output section of the matching box. In this case, the matching box may be affected by the high voltage. For this reason, a technology for adjusting the impedance on the load side electrically connected to the high frequency power supply is desired.

[0012] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a processing vessel, a high-frequency power supply, and a tube portion. The processing vessel is configured to perform plasma processing. The high-frequency power supply is configured to supply high-frequency waves to an electrode provided in the processing vessel. The tube portion is provided in the processing vessel. The tube portion includes a tubular outer conductor, a tubular inner conductor provided inside the outer conductor and spaced apart from the outer conductor, a dielectric portion provided between the outer conductor and the inner conductor, and a short-circuiting member that electrically shorts the outer conductor and the inner conductor. The tube portion is configured to adjust the impedance of a load side electrically connected to the high-frequency power supply. The outer conductor is electrically connected to a grounded conductor in the processing vessel. The inner conductor is electrically connected to the electrode.

[0013] Therefore, depending on the configuration of the tube section, the impedance on the load side electrically connected to the high-frequency power supply can be adjusted.

[0014] In one exemplary embodiment, the tube section is configured to assist the reactance component of the impedance on the load side electrically connected to the high-frequency power supply.

[0015] Thus, by assisting the reactance component, the influence of the high-frequency generated from the high-frequency power supply on the load side electrically connected to the high-frequency power supply can be reduced.

[0016] In one exemplary embodiment, the short-circuit member is a conductor or a capacitor.

[0017] In one exemplary embodiment, the high-frequency power supply supplies a high-frequency in at least one of the VHF band, UHF band, and microwave band to the electrode.

[0018] In one exemplary embodiment, the tube section is configured to introduce a driving force including at least one of gas, temperature-controlled fluid, and electrical wiring.

[0019] In one exemplary embodiment, the outer conductor extends upward from the upper surface of the upper wall of the processing container. The inner conductor extends upward from the electrode through the upper wall. A space is provided around the outside of the inner conductor to cover the inner conductor.

[0020] In one exemplary embodiment, the dielectric part is filled in a region that extends upward from the lower surface of the upper wall in the space covering the inner conductor.

[0021] In one exemplary embodiment, assuming that the wavelength of the high-frequency supplied from the high-frequency power supply to the electrode in the tube section is λg and the length of the region that extends upward from the lower surface of the upper wall is L, L is in the range of 0 < L < λg / 2.

[0022] In one exemplary embodiment, the device has a plurality of electrodes, with the inner conductor electrically connected to each of the plurality of electrodes.

[0023] In one exemplary embodiment, there are multiple tubes.

[0024] In one exemplary embodiment, the plurality of tubes are arranged on the top wall symmetrically about a central axis of the top wall of the process vessel.

[0025] Various exemplary embodiments will be described in detail below with reference to the drawings, in which the same or equivalent parts are designated by the same reference numerals.

[0026] An example of the configuration of a plasma processing apparatus 1 is shown in Fig. 1. The configuration of the plasma processing apparatus 1 will be described with reference to Fig. 1.

[0027] The plasma processing apparatus 1 includes a processing chamber 101, an upper wall 102, an electrode 103, a shower plate 106, gas holes 107, an insulating ring 108, a high frequency power supply 109, and a plurality of pipes CP.

[0028] The plasma processing apparatus 1 further includes a matching box 110, a high frequency introduction section 111, a high frequency propagation section 112, a high frequency emission section 113, a gas supply unit 114, an exhaust port 116, a sealing member 117, a processing space 119, a substrate 120, and a stage 121.

[0029] The plasma processing apparatus 1 further includes an outer conductor 200 , an inner conductor 201 , a dielectric portion 202 , a short-circuit member 203 , a coaxial filter 204 , a sealing member 205 , a heater power supply 206 , heater wiring 207 , an outer heater 208 , and an inner heater 209 .

[0030] The electrode 103 is provided in the processing vessel 101, facing the top wall 102 of the processing vessel 101, along the top wall 102. Two heaters (an outer heater 208 and an inner heater 209) are embedded inside the electrode 103. The outer heater 208 and the inner heater 209 may be, for example, sheath heaters.

[0031] The high-frequency power supply 109 is electrically connected to the electrode 103 via the matcher 110 and the high-frequency introduction part 111 of the upper wall 102. In one embodiment, a coaxial waveguide (not shown) may be provided in the high-frequency introduction part 111. The high-frequency generated from the high-frequency power supply 109 is applied to the electrode 103 via the matcher 110. A high-frequency propagation part 112, which is a space where high-frequency propagates, is provided between the upper wall 102 and the electrode 103.

[0032] The electrode 103 is supported and fixed by the insulating ring 108 in the processing container 101. The insulating ring 108 is provided along the side wall of the processing container 101. A sealing member 117 is provided on the joint surface between the electrode 103 and the insulating ring 108. The sealing member 117 improves the airtightness of each of the plurality of spaces (the space of the high-frequency propagation part 112 and the space between the electrode 103 and the shower plate 106) defined by the joint of the electrode 103 and the insulating ring 108.

[0033] The high-frequency power supply 109 is provided in the processing container 101 and is configured to supply high-frequency to the electrode 103. The high-frequency power supply 109 supplies a high-frequency voltage (hereinafter sometimes referred to as high-frequency) in at least one frequency band of the VHF band, UHF band, and microwave band to the electrode 103. The high-frequency output from the high-frequency power supply 109 is introduced into the processing container 101 from the high-frequency introduction part 111 via the matcher 110. The high-frequency propagates through the high-frequency propagation part 112 surrounding the electrode 103 and is emitted from the high-frequency emission part 113 to the processing space 119. The high-frequency excites plasma while propagating along the lower surface of the shower plate 106 as a surface wave.

[0034] The shower plate 106 is provided along the electrode 103 below the electrode 103. A space is provided between the electrode 103 and the shower plate 106, and this space communicates with a pipe portion CP connected to the gas supplier 114 via the electrode 103. The gas output from the gas supplier 114 diffuses into this space between the electrode 103 and the shower plate 106 through the pipe portion CP. Then, this gas is further supplied into a processing space 119 provided below the shower plate 106 through a plurality of gas holes 107 provided in the shower plate 106. Plasma of the gas released into the processing space 119 is generated by the high frequency released from the high frequency emission portion 113 into the processing space 119. The substrate 120 placed on the stage 121 is plasma processed by this plasma. The gas in the processing space 119 is discharged to the outside through the exhaust port 116.

[0035] The processing container 101 is configured to perform plasma processing. The processing container 101 is a conductor that is electrically grounded.

[0036] The processing container 101 is provided with a pipe portion CP. The pipe portion CP is configured to adjust the impedance on the load side that is electrically connected to the high frequency power supply 109. The pipe portion CP includes a coaxial filter 204. The coaxial filter 204 extends upward from the upper wall 102. The coaxial filter 204 includes a tubular outer conductor 200, a tubular inner conductor 201 provided spaced apart from the outer conductor 200 inside the outer conductor 200, and a dielectric portion 202 provided in the space between the outer conductor 200 and the inner conductor 201. The inner diameter b of the outer conductor 200 is larger than the outer diameter a of the inner conductor 201. The dielectric portion 202 can be a solid member or a gas (for example, air).

[0037] The outer conductor 200 is electrically connected to the processing container (particularly the upper wall 102). The outer conductor 200 extends upward from the upper surface of the upper wall 102 of the processing container 101. The inner conductor 201 is electrically connected to the electrode 103. The inner conductor 201 extends upward from the electrode 103 through the upper wall 102. A space is provided around the outside of the inner conductor 201 to cover the inner conductor 201. A sealing member 205 is provided at the joint surface of the inner conductor 201 and the electrode 103. By the sealing member 205, the airtightness of each of the plurality of spaces (the space of the high-frequency propagation part 112 and the space in the pipe part CP) defined by the joint of the inner conductor 201 and electrode 103 is improved. The outer conductor 200, the inner conductor 201, the dielectric part 202 provided in the space between the outer conductor 200 and the inner conductor 201, and the space provided around the outside of the inner conductor 201 to cover the inner conductor 201 constitute a coaxial filter 204. Note that the sealing member 205 is necessary for the coaxial filter 204 that guides gas or the like, but is unnecessary for the coaxial filter 204 that guides electrical wiring such as the heater wiring 207 electrically connected to the heater power supply 206.

[0038] The outer conductor 200 and the inner conductor 201 are made of a metal such as an aluminum alloy, copper, or stainless steel. The outer conductor 200 and the inner conductor 201 may be coated with a film such as gold plating, silver plating, or nickel plating. The pipe part CP including the coaxial filter 204 may be a bendable pipe (coaxial cable).

[0039] The pipe part CP further includes a short-circuit member 203 that electrically shorts the outer conductor 200 and the inner conductor 201. In one embodiment, the short-circuit member 203 can be a conductor such as a spiral ring or a capacitor. The short-circuit member 203 is provided near the upper ends of the outer conductor 200 and the inner conductor 201, and the outer conductor 200 and the inner conductor 201 are electrically short-circuited near their upper ends.

[0040] The coaxial filter 204 of the tube portion CP further includes a dielectric portion 202 provided between the outer conductor 200 and the inner conductor 201. The dielectric portion 202 fills a region of the space surrounding the inner conductor 201 that extends from the lower surface of the upper wall 102 to above the upper wall 102. The dielectric portion 202 may be made of an insulating material such as tetrafluoroethylene, aluminum oxide, or quartz. Note that the region of the space surrounding the inner conductor 201 that extends from the lower surface of the upper wall 102 to above the upper wall 102 may be filled with a gas instead of the dielectric portion 202.

[0041] The pipe section CP is configured to introduce utilities including at least one of gas, temperature-controlling fluid, and electrical wiring. In the configuration shown in Fig. 1, the pipe section CP introduces gas supplied from the gas supplier 114, and electrical wiring that electrically connects the heater power supply 206 with the outer heater 208 and the inner heater 209. The pipe section CP can also be used for a coaxial waveguide (not shown) provided in the high-frequency introduction section 111.

[0042] In one embodiment, the tube portion CP, together with the coaxial filter 204, may be a tube that is difficult to deform, or may be a tube that is flexible. The cross-sectional shape of the tube portion CP may be circular, or may be other shapes such as rectangular. The inner diameter of the outer conductor 200 and the outer diameter of the inner conductor 201 may be changed when bending.

[0043] In one embodiment, the plasma processing apparatus 1 may have a plurality of pipe parts CP. In this case, the plurality of pipe parts CP (a plurality of coaxial filters 204) are arranged on the upper wall 102 above the electrode 103, symmetrically with respect to the central axis of the upper wall 102. By arranging the plurality of coaxial filters 204 at symmetrical positions, deterioration of the circumferential distribution of plasma due to the introduction of the coaxial filters 204 is suppressed.

[0044] Next, the shape of the tube portion CP will be described. Let λg be the wavelength in the tube portion CP of the high frequency supplied from the high frequency power supply 109 to the electrode 103, and let L be the length of the region extending upward from the lower surface of the upper wall 102 above the upper wall 102. The impedance Zc of the coaxial filter 204 as seen from the lower end of the coaxial filter 204 (the lower surface of the upper wall 102) extending upward from the lower surface of the upper wall 102 is represented by the formula FM1 shown in FIG. 2.

[0045] Z0 included in the formula FM1 is the characteristic impedance of the coaxial filter 204, which is represented by the formula FM2 shown in FIG. 2, and εr is the relative dielectric constant of the dielectric portion 202. λg included in the formula FM1 is the wavelength in the coaxial filter 204 of the electromagnetic wave generated by the high frequency power supply 109, which is represented by the formula FM3 shown in FIG. 2. λ0 is the wavelength in vacuum. j is an imaginary number. That is, the impedance Zc of the coaxial filter 204 consists only of reactance.

[0046] The impedance Zc of the coaxial filter 204 changes periodically with a period of λg / 2 depending on the length L of the coaxial filter 204. Zc becomes an inductive reactance when L < λg / 4, and becomes a capacitive reactance when λg / 2 > L > λg / 4. Also, Zc becomes insulating when L = λg / 4.

[0047] Thus, L is in the range of 0 < L < λg / 2. By adjusting the length L of the coaxial filter 204 of the pipe portion CP, the impedance Zc of the coaxial filter 204 can be adjusted, and furthermore, the impedance on the load side electrically connected to the high-frequency power supply 109 can also be adjusted. The impedance Zc of the coaxial filter 204 provides only the reactance component as shown in Equation FM1 of FIG. 2. Therefore, by adjusting Zc, the reactance component of the impedance on the load side electrically connected to the high-frequency power supply 109 can be assisted (the reactance component can be adjusted (for example, reduced)). More preferably, the reactance component of the impedance on the load side can be eliminated (set to zero). In this case, the AC component is blocked in the load including the pipe portion CP and electrically connected to the high-frequency power supply 109, and discharges in the pipe portion CP that may occur due to high frequency, the influence of reflected waves on the high-frequency matcher 110 on the matcher 110, etc. can be avoided. It can reduce the output voltage of the matcher 110 before plasma ignition to suppress reflection after plasma ignition, thereby reducing the electrical load that may occur in the matcher 110 during plasma ignition and improving the power efficiency. By introducing gas, liquid, current, and signal into the electrode 103 to which a high-frequency voltage is applied through the pipe portion CP including the coaxial filter 204, the insulating material and low-pass filter provided in the configuration for introducing gas, liquid, current, and signal become unnecessary. Thereby, it is possible to avoid the complication of the configuration of the plasma processing apparatus 1. Also, discharges in the insulating portion due to overvoltage and the influence on the low-pass filter can be suppressed.

[0048] As described above, various exemplary embodiments have been described, but without being limited to the above-described exemplary embodiments, various additions, omissions, substitutions, and changes may be made. Also, it is possible to combine elements in different embodiments to form other embodiments.

[0049] For example, the plasma processing apparatus 1 may have a plurality of electrodes 103. In this case, the inner conductor 201 is electrically connected to each of the plurality of electrodes 103.

[0050] From the above description, it will be understood that the various embodiments of the present disclosure have been described herein for the purpose of illustration and that various changes can be made without departing from the scope and spirit of the present disclosure. Therefore, the various embodiments disclosed herein are not intended to be limiting, and the true scope and spirit are indicated by the appended claims.

Description of Reference Numerals

[0051] 1... Plasma processing apparatus, 101... Processing container, 102... Upper wall, 103... Electrode, 106... Shower plate, 107... Gas hole, 108... Insulating ring, 109... High-frequency power source, 110... Matching unit, 111... High-frequency introduction part, 112... High-frequency propagation part, 113... High-frequency emission part, 114... Gas supplier, 116... Exhaust port, 117... Sealing member, 119... Processing space, 120... Substrate, 121... Stage, 200... Outer conductor, 201... Inner conductor, 202... Dielectric part, 203... Short-circuit member, 204... Coaxial filter, 205... Sealing member, 206... Heater power source, 207... Heater wiring, 208... Outer heater, 209... Inner heater, CP... Pipe part.

Claims

1. A processing container configured to perform plasma processing, A high-frequency power supply configured to supply high-frequency power to an electrode provided in the processing container, A pipe portion provided in the processing container, Comprising, The pipe portion includes a tubular outer conductor, a tubular inner conductor provided inside the outer conductor and spaced apart from the outer conductor, a dielectric portion provided between the outer conductor and the inner conductor, and a short-circuit member that electrically shorts the outer conductor and the inner conductor, and is configured to adjust the impedance on the load side electrically connected to the high-frequency power supply, The outer conductor is electrically connected to the grounded conductor of the processing container, The inner conductor is electrically connected to the electrode, A plasma processing apparatus.

2. The pipe portion is configured to assist the reactance component of the impedance on the load side electrically connected to the high-frequency power supply. The plasma processing apparatus according to Claim 1.

3. The short-circuit member is a conductor or a capacitor. The plasma processing apparatus according to Claim 1 or 2.

4. The high-frequency power supply supplies high-frequency power in at least one frequency band of the VHF band, UHF band, and microwave band to the electrode. The plasma processing apparatus according to any one of Claims 1 to 3.

5. The pipe portion is configured to introduce a driving force including at least one of gas, temperature control fluid, and electrical wiring. The plasma processing apparatus according to any one of Claims 1 to 4.

6. The outer conductor extends upward from the upper surface of the upper wall of the processing container, The inner conductor extends upward from the electrode through the upper wall, A space covering the inner conductor is provided around the outside of the inner conductor. The plasma processing apparatus according to any one of Claims 1 to 5.

7. The dielectric portion is filled in a region extending upward from the lower surface of the upper wall in the space covering the inner conductor. The plasma processing apparatus according to Claim 6.

8. When the wavelength of the high-frequency power supplied from the high-frequency power supply to the electrode in the pipe portion is λg and the length of the region extending upward from the lower surface of the upper wall is L, the L is in the range of 0 < L < λg / 2. The plasma processing apparatus according to Claim 7.

9. Having a plurality of the electrodes, The inner conductor is electrically connected to each of the plurality of electrodes. The plasma processing apparatus according to any one of Claims 1 to 8.

10. Having a plurality of said tube portions The plasma processing apparatus according to any one of claims 1 to 9

11. The plurality of said tube portions are arranged on the upper wall symmetrically about the central axis of the upper wall of the processing container The plasma processing apparatus according to claim 10

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