Matching unit and plasma processing unit

Abstract

This invention provides technology for matching circuits that can handle high frequencies, and technology for plasma processing equipment having such matching circuits. [Solution] The disclosed matching device comprises a plurality of reactance elements, a plurality of relays, a ground element, and an inductor element. The plurality of reactance elements are connected to a high-frequency supply line for high-frequency power for plasma generation. The plurality of relays include relay switches and relay coils, each having a first contact connected to each of the plurality of reactance elements. The ground element is connected to a second contact different from the first contact of some of the plurality of relay switches. The inductor element is connected to a third contact different from the first contact of the remaining relay switches and is also connected to a high-frequency supply line. The plurality of reactance elements include a lower electrode, a dielectric plate, a plurality of first upper electrodes, and a plurality of second upper electrodes.

Description

[Technical Field]

[0001] Exemplary embodiments of this disclosure relate to matching devices and plasma processing devices. [Background technology]

[0002] Patent Document 1 discloses an embodiment of a matching network including a switchable variable capacitor circuit. The switchable variable capacitor circuit includes between 1 and 100 fixed capacitors. The fixed capacitors are all connected to a first terminal and selectively connected to a second terminal. A switch selectively controls whether the fixed capacitors are connected to the second terminal. Varying the number of fixed capacitors connected to the second terminal changes the net effective capacitance of the switch capacitor. To match the plasma load impedance to a desired input impedance, the matching network further includes a fixed inductor and a second variable capacitor. An example of a switch is a PIN diode. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Special Publication No. 2014-505983 [Overview of the Initiative] [Problems that the invention aims to solve]

[0004] This disclosure provides technology for high-frequency matching devices and technology for plasma processing devices having such matching devices. [Means for solving the problem]

[0005] In one exemplary embodiment, a matching device is provided. The matching device comprises a plurality of reactance elements, a plurality of relays, a ground element, and an inductor element. The plurality of reactance elements are connected to a high-frequency supply line for high-frequency power for plasma generation. The plurality of relays include relay switches and relay coils, each having a first contact connected to each of the plurality of reactance elements. The ground element is connected to a second contact different from the first contact of some of the plurality of relay switches. The inductor element is connected to a third contact different from the first contact of the remaining relay switches, and is also connected to the high-frequency supply line. The plurality of reactance elements include a lower electrode, a dielectric plate, a plurality of first upper electrodes, and a plurality of second upper electrodes. The lower electrode consists of a single continuous metallic pattern. The dielectric plate is configured on top of the lower electrode. The first upper electrode is provided on top of the dielectric plate so as to face the lower electrode via the dielectric plate. The first upper electrode is connected to the first contact of a relay switch having a third contact connected to the inductor element. Multiple first upper electrodes are arranged along a first direction. A second upper electrode is provided on a dielectric plate so as to face the lower electrode via a dielectric plate. The second upper electrode is connected to the first contact of a relay switch having a second contact connected to a ground element. The second upper electrode faces the first upper electrode in a second direction intersecting the first direction. Multiple second upper electrodes are arranged along a first direction. Multiple first upper electrodes are arranged along a first direction such that the capacitance formed between the first upper electrode and the lower electrode changes by a power of 2 as you move from one direction to the other in the first direction, in accordance with the change in the area of ​​the first upper electrode. Multiple second upper electrodes are arranged along a first direction such that the capacitance formed between the second upper electrode and the lower electrode changes by a power of 2 as you move from one direction to the other in the first direction, in accordance with the change in the area of ​​the second upper electrode. [Effects of the Invention]

[0006] According to one exemplary embodiment, techniques for handling high frequencies of matching devices and techniques for plasma processing devices having such matching devices are provided. [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] This is a diagram showing a matching device according to one exemplary embodiment. [Figure 4] Figure 3 is a schematic cross-sectional view of the matching device shown. [Figure 5] An example of an equivalent circuit for an L-type matching circuit in a comparative example, and the matching range of the load impedance at a frequency of 200 MHz calculated using said equivalent circuit. [Figure 6] This figure shows a matching device according to another exemplary embodiment. [Figure 7] Figure 6 is a schematic cross-sectional view of the matching device shown. [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, a high-frequency power supply 24, and a matching unit 30.

[0010] Chamber 10 provides a processing space 10s inside it. In the plasma processing apparatus 1, the substrate W is processed within the processing space 10s. Chamber 10 is formed of a metal such as aluminum and is grounded. Chamber 10 has side walls 10a and is open at its upper end. Chamber 10 and side walls 10a may have a substantially cylindrical shape. The processing space 10s is provided inside the side walls 10a. The central axis of each of chamber 10, side walls 10a, and processing space 10s is axis AX. Chamber 10 may have a film with corrosion resistance on its surface. The film with corrosion resistance may be a ceramic film containing a yttrium oxide film, a yttrium fluoride oxide film, a yttrium fluoride film, yttrium oxide, or yttrium fluoride, etc.

[0011] The bottom of chamber 10 provides an exhaust port 10e. An exhaust device is connected to the exhaust port 10e. The exhaust device may include a vacuum pump such as a dry pump and / or a turbo molecular pump and an automatic pressure control valve.

[0012] The substrate support 12 is provided within the processing space 10s. The substrate support 12 is configured to support the substrate W placed on its upper surface substantially horizontally. The substrate support 12 has a substantially disc shape. The central axis of the substrate support 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 12 via the processing space 10s. The upper electrode 14 is formed of 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 constitutes an excitation electrode together with a shower plate 22 described later.

[0014] The introduction part 16 is provided to emit electromagnetic waves from there to the plasma generation region. In the plasma processing apparatus 1, the plasma generation region is a space within the processing space 10s and directly below the excitation electrode, that is, directly below the shower plate 22. In the plasma processing apparatus 1, the gas in the plasma generation region is excited by the electromagnetic waves emitted from the introduction part 16 to the plasma generation region, and plasma is generated. The electromagnetic waves emitted from the introduction part 16 to the plasma generation region can be high-frequency waves such as VHF waves or UHF waves. The introduction part 16 is formed of a dielectric such as quartz, aluminum nitride, or aluminum oxide. In one embodiment, the introduction part 16 is provided at the lateral end of the processing space 10s and extends in the circumferential direction around the axis AX. The introduction part 16 may have an annular shape.

[0015] The resonator 20 includes a power supply part 20p and a waveguide 20w. The power supply part 20p is an entrance of electromagnetic waves to the waveguide 20w of the resonator 20. The electromagnetic waves are generated based on the high-frequency power generated by the high-frequency power supply 24. The high-frequency power supply 24 may be configured to be able to change the frequency of the output high-frequency power. As an example, the high-frequency power can be 100 MHz or more. The electromagnetic waves are input to the power supply part 20p of the resonator 20 via the high-frequency supply line 40. The resonator 20 resonates the electromagnetic waves input to the power supply part 20p in the waveguide 20w and propagates them to the introduction part 16. The electromagnetic waves are introduced from the introduction part 16 to the plasma generation region. In one embodiment, the resonator 20 may be provided 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 and a coaxial connector 41c 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 which 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. The outer conductor 40o is electrically connected to the wall of the resonator 20 which defines the upper part 20a from above and to the grounded housing 30h (e.g., a metal housing) of the matching unit 30.

[0017] The coaxial connector 41c includes an inner conductor 41i and an outer conductor 41o. The outer conductor 41o has a cylindrical shape and surrounds the inner conductor 41i. The inner conductor 41i and the outer conductor 41o extend coaxially. The outer conductor 41o is electrically connected to the housing 30h. A dielectric member 41p is disposed between the inner conductor 41i and the outer conductor 41o. The dielectric member 41p may have a cylindrical shape. The dielectric member 41p may be formed from, for example, polytetrafluoroethylene. The inner conductor 41i, the outer conductor 41o, and the dielectric member 41p may constitute a capacitor.

[0018] In one embodiment, the plasma processing apparatus 1 may further include a shower plate 22. The shower plate 22 may be formed from a metal such as aluminum. The introduction section 16 extends to surround the shower plate 22. The introduction section 16 and the shower plate 22 are arranged 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 located below 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 between them. The central axis of the gas diffusion space 14d may be axis AX. Multiple gas holes 22h of the shower plate 22 are connected to the gas diffusion space 14d. The upper electrode 14 also provides an inlet 14h. The inlet 14h may extend along axis AX. The inlet 14h is connected to the gas diffusion space 14d. A gas supply unit 26 is connected to the gas diffusion space 14d. The gas output from the gas supply unit 26 is supplied to the processing space 10s via the inlet 14h, the gas diffusion space 14d, and the multiple gas holes 22h.

[0020] Hereinafter, Figure 2 will be referenced along with Figure 1. Figure 2 shows the lower part of a resonator in a plasma processing apparatus according to one exemplary embodiment. Figure 2 is a cross-sectional view taken along the line II-II in Figure 1. The waveguide 20w of the resonator 20 may provide a cavity surrounded by walls. The walls of the waveguide 20w are formed from a material such as metal. The walls of the waveguide 20w may be formed from an aluminum alloy, copper, nickel, or stainless steel, 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 section 16.

[0022] In one embodiment, the wall of the resonator 20 may include an inner circumferential portion 20i and an outer circumferential portion 20o. The inner circumferential portion 20i extends around its central axis, axis AX, and has a substantially cylindrical shape. The outer circumferential portion 20o extends coaxially with the inner circumferential portion 20i around axis AX. The outer circumferential portion 20o may also have a substantially cylindrical shape.

[0023] The waveguide 20w may have a layered structure that alternately folds between an inner circumferential portion 20i and an outer circumferential portion 20o. The walls of the waveguide 20w may include a plurality of walls that extend radially and circumferentially between adjacent layers of the layered structure and between the inner circumferential portion 20i and the outer circumferential portion 20o. The plurality of walls may be annular plates.

[0024] Furthermore, the waveguide 20w may include an upper part 20a constituting the uppermost layer of the layered structure and a lower part 20b constituting the lowest layer of the layered structure. The layered structure may also include an intermediate part 20c between the upper part 20a and the lower part 20b. In this embodiment, the upper part 20a may provide the first end 201, i.e., the upper end, of the waveguide 20w at the outer periphery 20o. In this case, the first end 201 of the waveguide 20w extends circumferentially around the axis AX. Furthermore, the lower part 20b may provide the second end 202, i.e., the lower end, of the waveguide 20w at the outer periphery 20o. In this case, the second end 202 of the waveguide 20w extends circumferentially 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 circumferentially around the axis AX. Electromagnetic waves resonating in the resonator 20 propagate electromagnetically to the introduction section 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] The matching unit 30 includes a housing 30h, a directional coupler 31, a matching circuit 32, a matching control unit 33, and a relay drive unit 34. The directional coupler 31, the matching circuit 32, the matching control unit 33, and the relay drive unit 34 are housed in the housing 30h. The directional coupler 31 and the matching circuit 32 are connected to the high-frequency supply line 40 in this order.

[0029] The directional coupler 31 measures the amplitude and phase difference of the incident and reflected waves at the input of the matching circuit 32. The directional coupler 31 outputs a signal to the matching control unit 33 that reflects the power level of the reflected high-frequency power. The matching circuit 32 is, as an example, an L-type matching circuit including variable capacitors CA and CB and an inductor L (inductor element).

[0030] The matching control unit 33 is electrically connected to the directional coupler 31 and can receive signals from the directional coupler 31. The matching control unit 33 includes a control circuit and a communication circuit. The control circuit of the matching control unit 33 may consist of a programmable processor such as a CPU or MPU, a programmable logic device such as an FPGA (Field Programmable Gate Array), or a dedicated circuit such as an ASIC (Application Specific Integrated Circuit).

[0031] The relay drive unit 34 is electrically connected to the matching control unit 33 and can receive signals from the matching control unit 33. The relay drive unit 34 is electrically connected to the matching circuit 32 and can output signals to the matching circuit 32. The relay drive unit 34d is configured to drive the matching circuit 32 to adjust the variable impedance of the matching circuit 32. The matching control unit 33 is configured to control the relay drive unit 34 to adjust the impedance of the matching circuit 32. In one embodiment, the matching control unit 33 outputs signals to the relay drive unit 34 to control the opening and closing of a plurality of relays in the matching circuit 32, which will be described later, based on signals from the directional coupler 31. The relay drive unit 34 generates a voltage to drive the relay coils based on signals from the matching control unit 33.

[0032] Figure 3 shows a matching circuit according to one exemplary embodiment. Figure 4 is a schematic cross-sectional view of the matching circuit shown in Figure 3. As shown in Figures 3 and 4, the matching circuit 30 has a printed circuit board 50 (dielectric plate). The printed circuit board 50 includes an upper surface 50a and a lower surface 50b opposite to the upper surface 50a. In this disclosure, "upper" and "lower" merely define the relative positional relationship of each element and do not necessarily limit it to up and down with respect to the direction of gravity. The directional coupler 31 is provided on the upper surface 50a of the printed circuit board 50. The printed circuit board 50 is made of a material with a low dielectric loss tangent, such as tetrafluoroethylene.

[0033] The matching unit 30 has multiple (10 in one example) capacitors CA1-CA5, CB1-CB5 (reactance elements), multiple (10 in one example) relays RLA1-RLA5, RLB1-RLB5, a ground pattern 51 (ground element), and an inductor pattern 52 (inductor element). The multiple capacitors CA1-CA5, CB1-CB5 are connected to a high-frequency supply line 40 for high-frequency power for plasma generation. Capacitors CA1-CA5 refer to capacitors CA1, CA2, CA3, CA4, and CA5. Capacitors CB1-CB5 refer to capacitors CB1, CB2, CB3, CB4, and CB5. Relays RLA1-RLA5 refer to relays RLA1, RLA2, RLA3, RLA4, and RLA5. Relays RLB1~RLB5 refer to relays RLB1, RLB2, RLB3, RLB4, and RLB5, respectively.

[0034] Each of the relays RLA1 to RLA5 includes a relay switch 61s and a relay coil 61c. Each relay switch 61s includes a first contact 61a connected to each of the capacitors CA1 to CA5, and a third contact 61b connected to the inductor pattern 52. The relay switch 61s can switch the connection and disconnection between the first contact 61a and the third contact 61b depending on the state (open or closed) of the first contact 61a and the third contact 61b. Each relay coil 61c is electrically connected to a relay drive unit 34, from which a DC voltage signal can be applied to set the state (open or closed) of the relay switch 61s.

[0035] Each of the relays RLB1 to RLB5 includes a relay switch 71s and a relay coil 71c. Each relay switch 71s includes a first contact 71a connected to each of the capacitors CB1 to CB5, and a second contact 71b connected to the ground pattern 51. The relay switch 71s can switch the connection between the first contact 71a and the second contact 71b depending on the state (open or closed) of the first contact 71a and the second contact 71b. Each relay coil 71c is electrically connected to a relay drive unit 34, from which a DC voltage signal can be applied to set the state (open or closed) of the relay switch 71s.

[0036] The ground pattern 51 is provided on the lower surface 50b of the printed circuit board 50. As described above, the ground pattern 51 is connected to the second contact 71b of the relay switch 71s of some of the relays RLB1 to RLB5 among the multiple relays RLA1 to RLA5, RLB1 to RLB5. The ground pattern 51 can be connected to the housing 30h via a metal support column 55.

[0037] The inductor pattern 52 constitutes an inductor L. The inductor pattern 52 is provided on the lower surface 50b of the printed circuit board 50. As described above, the inductor pattern 52 is connected to the third contact 61b of the relay switch 61s of the remaining relays RLA1 to RLA5 out of the multiple relays RLA1 to RLA5, RLB1 to RLB5. One end of the inductor pattern 52 can be connected to the output coaxial connector 40c.

[0038] The matching circuit 30 has a lower electrode 53, a plurality (five in one example) of first upper electrodes 54a, and a plurality (five in one example) of second upper electrodes 54b. Each of the lower electrode 53, the first upper electrodes 54a, and each of the second upper electrodes 54b consists of a continuous metal pattern (e.g., a copper pattern). The lower electrode 53 is formed on the lower surface 50b of the printed circuit board 50. In other words, the printed circuit board 50 is constructed on the lower electrode 53. One end of the lower electrode 53 can be connected to the input-side coaxial connector 41c.

[0039] The first upper electrodes 54a are formed on the upper surface 50a of the printed circuit board 50. That is, each of the multiple first upper electrodes 54a is provided on the printed circuit board 50 so as to face the lower electrode 53 via the printed circuit board 50. Each of the multiple first upper electrodes 54a is connected to the first contact 61a of a relay switch 61s having a third contact 61b connected to an inductor pattern 52. The multiple first upper electrodes 54a are arranged along a first direction D1 along the upper surface 50a.

[0040] The second upper electrodes 54b are formed on the upper surface 50a of the printed circuit board 50. That is, each of the multiple second upper electrodes 54b is provided on the printed circuit board 50 so as to face the lower electrode 53 via the printed circuit board 50. Each of the multiple second upper electrodes 54b is connected to the first contact 71a of a relay switch 71s having a second contact 71b connected to a ground pattern 51. The multiple second upper electrodes 54b are arranged along a first direction D1. Each of the multiple second upper electrodes 54b faces each of the first upper electrodes 54a in a second direction D2 that is along the upper surface 50a and intersects the first direction D1. Therefore, in one embodiment, the number of first upper electrodes 54a and second upper electrodes 54b are equal.

[0041] In the matching circuit 30, one capacitor (each of the capacitors CA1 to CA5) is formed by one first upper electrode 54a, a region of the lower electrode 53 facing the first upper electrode 54a, and a printed circuit board 50 interposed between the first upper electrode 54a and the lower electrode 53. In the illustrated example, the capacitors CA1 to CA5 are arranged sequentially from one side (negative side) to the other side (positive side) in the first direction D1.

[0042] The capacitances of capacitors CA1 to CA5 correspond to (approximately proportional to) the area of ​​the first upper electrode 54a. The capacitances of capacitors CA1 to CA5 are affected by stray capacitance, stray inductance, and the surrounding structure, so these effects may also be taken into consideration. The multiple first upper electrodes 54a are arranged along the first direction D1 such that the capacitance (of capacitors CA1 to CA5) formed between the first upper electrode 54a and the lower electrode 53 changes by a power of 2 (decreases in this case) as you move from one side of the first direction D1 to the other, in accordance with the change in the area of ​​the first upper electrode 54a. Therefore, the capacitance of capacitor CAn (where n is an integer from 1 to 4) is set to 2 × CA(n+1). However, the capacitance of capacitor CA5 may be defined, for example, as the minimum capacitance Cr. In the illustrated example, each of the multiple first upper electrodes 54a is rectangular in shape and is arranged such that its area decreases by approximately a power of 2 as you move from one side to the other in the first direction D1.

[0043] Furthermore, in the matching circuit 30, one capacitor (each of the capacitors CB1 to CB5) is formed by one second upper electrode 54b, a region of the lower electrode 53 facing the said second upper electrode 54b, and a printed circuit board 50 interposed between the second upper electrode 54b and the lower electrode 53. In the illustrated example, the capacitors CB1 to CB5 are arranged in order from the other side (positive side) to the one side (negative side) of the first direction D1.

[0044] The capacitances of capacitors CB1 to CB5 correspond to (approximately proportional to) the area of ​​the second upper electrode 54b. The capacitances of capacitors CB1 to CB5 are affected by stray capacitance, stray inductance, and the surrounding structure, so these effects may also be taken into consideration. The multiple second upper electrodes 54b are arranged along the first direction D1 such that the capacitance (of capacitors CB1 to CB5) formed between the second upper electrode 54b and the lower electrode 53 changes by a power of 2 (decreases in this case) as you move from one side of the first direction D1 to the other, in accordance with the change in the area of ​​the second upper electrode 54b. Therefore, the capacitance of capacitor CBn (where n is an integer from 1 to 4) is set to 2 × CB(n+1). However, the capacitance of capacitor CB5 may be defined, for example, as the minimum capacitance Cr. Note that the capacitance Cr of capacitor CA5 and the capacitance Cr of capacitor CB5 are the same as an example, but they may be different.

[0045] In the illustrated example, each of the multiple second upper electrodes 54b is rectangular in shape and is arranged such that its area decreases by approximately a power of 2 as you move from one end of the first direction D1 to the other. Therefore, among the second upper electrodes 54b constituting capacitors CB1 to CB5, the second upper electrodes 54b with relatively large areas are positioned opposite the first upper electrodes 54a constituting capacitors CA1 to CA5 with relatively small areas in the second direction D2. In other words, the multiple first upper electrodes 54a and the multiple second upper electrodes 54b can be arranged along the first direction D1 such that the first upper electrodes 54a and second upper electrodes 54b facing the second direction D2 are complementary to each other (for example, so that the sum of their areas is constant). More specifically, as an example, in the second direction, the first upper electrode 54a constituting the capacitor CAn(n=1~5) and the second upper electrode 54b constituting the capacitor CB(5-n+1) are arranged to face each other.

[0046] The lower electrode 53 has a continuous region (in this case, rectangular) that encompasses all of the first upper electrodes 54a and second upper electrodes 54b arranged as described above, when viewed from a third direction D3 that intersects the first direction D1 and the second direction D2. The lower electrode 53 may have slits interposed between the first upper electrodes 54a adjacent to each other in the first direction D1, as viewed from the third direction D3. Furthermore, the lower electrode 53 may have slits interposed between the second upper electrodes 54b adjacent to each other in the first direction D1, as viewed from the third direction D3. These slits may extend inward from the outer edge of the lower electrode 53 in the second direction D2.

[0047] Here, let Cr be the required capacitance resolution of the capacitance variable section in the matching circuit, Cm be the maximum capacitance, and N be the number of relays. If the capacitance of each capacitor is the same, then N = Cm / Cr. In contrast, in the matching circuit 30, the capacitances of capacitors CA1 to CA5 are Cn = Cr × 2 (n-1) For n=1 to N, the number of relays is minimized to N = log2(Cm / Cr) + 1. Since the parasitic capacitance between the terminals of the capacitance variable section (e.g., capacitors CA1 to CA5 and relays RLA1 to RLA5) and between the capacitance variable section and ground is proportional to the number of relays, the matching circuit 30 can minimize the parasitic capacitance.

[0048] Furthermore, the matching unit 30 shares a common capacitor pattern (for example, the lower electrode 53) that constitutes the two capacitance variable sections. The two capacitance variable sections are, for example, the variable capacitors CA and CB in Figure 3, which consist of capacitors CA1 to CA5 and relays RLA1 to RLA5, and capacitors CB1 to CB5 and relays RLB1 to RLB5. This eliminates the need for wiring between the capacitance variable sections, thereby minimizing parasitic inductance caused by the wiring.

[0049] Furthermore, in the matcher 30, for the capacitors CAn and CBn (n = 1 to N) that constitute the two variable capacitance parts, the capacitor CAn and the capacitor CB(N - n + 1) are arranged adjacent to each other. Thereby, the area of the capacitor pattern can be minimized. As a result, the parasitic capacitance between the capacitor pattern and the ground can be minimized. Thus, in the matcher 30, by minimizing the parasitic capacitance and the parasitic inductance, the matching time can be shortened to 10 msec or less, and it can support high frequencies of several 100 MHz or more.

[0050] FIG. 5 is an example of an equivalent circuit of an L-type matching circuit according to a comparative example, and a matching possible range (Smith chart) of load impedance at a frequency of 200 MHz calculated using the equivalent circuit. In (a) of FIG. 5, X ld is the load impedance, L ld is the inductance of the matching inductor, C ld , C tn is the capacitance of the variable capacitor for matching. Also, L rl is the stray inductance in the variable capacitor for matching, and L it is the inductance of the wiring between the variable capacitance parts.

[0051] (b) and (c) of FIG. 5 are the matching possible ranges (Smith charts) of load impedance at a frequency of 200 MHz calculated using the equivalent circuit of (a) of FIG. 5. In the calculation, the values of each reactance are set assuming a matching circuit using a relay. (b) of FIG. 5 is the case where there is no wiring between the variable capacitance parts (for example, in the case of the matching circuit 32, L it = 0 nH, L rl = 40 nH, L ld = 40 nH). (c) of FIG. 5 is the case where a 40 nH wiring is connected between the variable capacitance parts (L it = 40 nH, L rl = 40 nH, L ldCapacitance C) = 0nH). In other words, to adjust the matching range, the inductance of the matching inductor is adjusted so that the series inductance on the Load side is 80nH. The series inductance on the Tune side is 40nH in the case of Figure 5(b) and 80nH in the case of Figure 5(c). Capacitance C ld ,C tn The capacitance is independently varied within the range of 5pF to 16pF.

[0052] The curves Ci1 and Ci2 in Figure 5(b) represent capacitance C. tn This is the trajectory of the reflection coefficient when the capacitance is at its minimum value (5pF). To match a load impedance around 50Ω, it is desirable for the curve to pass near the center of the Smith chart. The curve passes through the center of the Smith chart when the series reactance on the Tune side is infinitely negative. In Figure 5(c), the series inductance on the Tune side is larger than in Figure 5(b), so the curve Ci2 is further away from the center of the Smith chart. When the load impedance is resistive, the maximum impedance that can be matched is 41.5Ω in Figure 5(b), compared to 29.9Ω in Figure 5(c). In this way, the matching range can be expanded by eliminating the wiring between the capacitance variable sections and reducing the series inductance on the Tune side.

[0053] The capacitance resolution Cr of the capacitance variable section within the matching circuit is given by Cr = (Cm - C0) / 2, where Cm is the maximum capacitance, C0 is the capacitance when all relays are open, and N is the number of relays. N This is expressed as follows. C0 includes parasitic capacitance around the capacitor pattern and around the relay. In order to set the capacitance to the desired value by opening and closing the relay, Cr must be smaller than the variation in Cm.

[0054] Tetrafluoroethylene can be used as the dielectric material for the dielectric plate (e.g., printed circuit board 50). Tetrafluoroethylene has a transition point around 23°C where the coefficient of linear expansion changes significantly, and its dimensions change by about 1% for a temperature change of 50°C that crosses the transition point. Due to changes in ambient temperature and heating due to high-frequency losses, the dimensions of the dielectric plate change, and Cm and C0 may change by about 1%. Cm is also affected by the distribution of the high-frequency electromagnetic field propagating within the resonator case. Therefore, it is desirable that Cr be 1% or less of Cm, and that the number of relays N be 6 or less. Accordingly, in the matching unit 30, the number N of relays RLAn, RLBn (n=1~N) can be set to 2 or more and 6 or less.

[0055] Figure 6 shows a matching circuit according to another exemplary embodiment. Figure 7 is a schematic cross-sectional view of the matching circuit shown in Figure 6. The matching circuit 30A shown in Figures 6 and 7 will be described below in terms of differences from the matching circuit 30.

[0056] The matching unit 30A has a first printed circuit board 50L, a second printed circuit board 50U, and a dielectric layer 50M instead of the printed circuit board 50. The second printed circuit board 50U is provided on top of the first printed circuit board 50L. The dielectric layer 50M is a dielectric plate interposed between the first printed circuit board 50L and the second printed circuit board 50U. Of the first printed circuit board 50L, the second printed circuit board 50U, and the dielectric layer 50M, at least the dielectric layer 50M may be made of, for example, tetrafluoroethylene.

[0057] In the matching circuit 30A, the metal pattern 58 to which the ground pattern 51, the lower electrode 53, and the third contact 61b of the relay switch 61s are connected is provided on the lower surface 50b of the first printed circuit board 50L. In other words, the first printed circuit board 50L, the dielectric layer 50M, and the second printed circuit board 50U are dielectric plates configured on the lower electrode 53. The lower surface 50b of the first printed circuit board 50L is the surface of the first printed circuit board 50L that faces away from the second printed circuit board 50U.

[0058] Multiple first upper electrodes 54a and multiple second upper electrodes 54b are each provided on the upper surface 50a of the second printed circuit board 50U. That is, multiple first upper electrodes 54a and multiple second upper electrodes 54b are each provided on the dielectric plate so as to face the lower electrode 53 via the dielectric plate. The upper surface 50a of the second printed circuit board 50U is the surface of the second printed circuit board 50U that faces away from the first printed circuit board 50L.

[0059] In the matching unit 30A, the inductor L is composed of a coil (e.g., copper wire) connected to the metal pattern 58. Therefore, in the matching unit 30A, the third contact 61b of the relay switch 61s is connected to the inductor L via the metal pattern 58. As an example, in the matching unit 50B, the directional coupler 31 is provided on the surface of the first printed circuit board 50L facing the second printed circuit board 50U. In the matching unit 30A, the inductance can be easily adjusted by changing the inductor L, which is composed of a coil.

[0060] The plasma processing apparatus 1 may be equipped with a matching circuit 30A instead of the matching circuit 30. Furthermore, the matching circuits 30 and 30A have a matching circuit 32 which is an L-type matching circuit as an example, but may also have a π-type or T-type matching circuit.

[0061] 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.

[0062] Herein, various exemplary embodiments included in this disclosure are described in [E1] to [E12] below.

[0063] [E1] Multiple reactance elements connected to a high-frequency supply line for high-frequency power for plasma generation, A plurality of relays, each having a first contact connected to each of the plurality of reactance elements, including relay switches and relay coils, A ground element to which a second contact different from the first contact of the relay switch of some of the relays among the plurality of relays is connected, The third contact of the relay switch of the remaining relays among the plurality of relays, which is different from the first contact, is connected to an inductor element connected to the high-frequency supply line, Equipped with, The aforementioned plurality of reactants are A lower electrode consisting of a continuous single metal pattern, A dielectric plate configured on the lower electrode, and a plurality of first upper electrodes arranged along a first direction, which are provided on the dielectric plate so as to face the lower electrode via the dielectric plate, and are connected to the first contact of the relay switch having the third contact connected to the inductor element, A plurality of second upper electrodes are provided on the dielectric plate so as to face the lower electrode via the dielectric plate, and are connected to the first contact of the relay switch having the second contact connected to the ground element, and are arranged along the first direction while facing the first upper electrode in a second direction intersecting the first direction, Includes, The plurality of first upper electrodes are arranged along the first direction such that the capacitance formed between the first upper electrodes and the lower electrodes changes by a factor of 2 as you move from one direction to the other, in accordance with the change in the area of ​​the first upper electrodes. The plurality of second upper electrodes are arranged along the first direction such that the capacitance formed between the second upper electrode and the lower electrode changes by a factor of 2 as you move from the other to the one in the first direction, in accordance with the change in the area of ​​the second upper electrode. Matching box.

[0064] [E2] A directional coupling circuit associated with the aforementioned high-frequency supply line, A matching control unit that controls the opening and closing of the plurality of relays based on the signal from the directional coupling circuit, The matching circuit described in E1 further includes the following:

[0065] [E3] The number of relays connected to the first upper electrode and the number of relays connected to the second upper electrode are, each, between 2 and 6. The matching device described in E1 or E2 above.

[0066] [E4] The frequency of the aforementioned high-frequency power is 100 MHz or higher. Matching device as described in E1 to E3.

[0067] [E5] The dielectric plate is First printed circuit board and A second printed circuit board is provided on the first printed circuit board, A dielectric layer interposed between the first printed circuit board and the second printed circuit board, Includes, The lower electrode is provided on the surface of the first printed circuit board facing the opposite side from the second printed circuit board. The plurality of first upper electrodes and the plurality of second upper electrodes are each provided on the surface of the second printed circuit board facing the side opposite to the first printed circuit board. Matching device as described in E1 to E4.

[0068] [E6] A matching circuit described in any of E1 to E5, Chamber and, An introduction unit arranged to introduce electromagnetic waves into the plasma generation region within the chamber, High-frequency power supply and The high-frequency supply line electrically connected to the 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 plasma processing device equipped with the following features.

[0069] 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]

[0070] 1…Plasma processing device, 10…Chamber, 16…Inlet, 20…Resonator, 20w…Waveguide, 20p…Power supply, 201…First end, 202…Second end, 24…High-frequency power supply, 30,30A…Matching unit, 31…Directional coupler, 40…High-frequency supply line, 50…Printed circuit board (dielectric plate), 50L…First printed circuit board (dielectric plate), 50U…Second printed circuit board (dielectric plate), 50M…Dielectric layer (dielectric plate), 51…Ground pattern (ground element), 52…Inductor Turn (inductor element), 53...lower electrode, 54a...first upper electrode, 54b...second upper electrode, 61a...first contact, 61b...third contact, 61c...relay coil, 61s...relay switch, 71a...first contact, 71b...second contact, 71c...relay coil, 71s...relay switch, CA1~CA5...capacitor (reactance element), CB1~CB5...capacitor (reactance element), L...inductor (inductor element), RLA1~RLA5...relay, RLB1~RLB5...relay.

Claims

1. Multiple reactance elements connected to a high-frequency supply line for high-frequency power for plasma generation, A plurality of relays, each having a first contact connected to each of the plurality of reactance elements, including relay switches and relay coils, A ground element to which a second contact different from the first contact of the relay switch of some of the relays among the plurality of relays is connected, The third contact of the relay switch of the remaining relays among the plurality of relays, which is different from the first contact, is connected to an inductor element connected to the high-frequency supply line, Equipped with, The aforementioned plurality of reactants are A lower electrode consisting of a continuous single metal pattern, A dielectric plate configured on the lower electrode, A plurality of first upper electrodes are provided on the dielectric plate so as to face the lower electrode via the dielectric plate, and are connected to the first contact of the relay switch having the third contact connected to the inductor element, and are arranged along the first direction, A plurality of second upper electrodes are provided on the dielectric plate so as to face the lower electrode via the dielectric plate, and are connected to the first contact of the relay switch having the second contact connected to the ground element, and are arranged along the first direction while facing the first upper electrode in a second direction intersecting the first direction, Includes, The plurality of first upper electrodes are arranged along the first direction such that the capacitance formed between the first upper electrodes and the lower electrodes changes by a factor of two as you move from one direction to the other, in accordance with the change in the area of ​​the first upper electrodes. The plurality of second upper electrodes are arranged along the first direction such that the capacitance formed between the second upper electrode and the lower electrode changes by a factor of two as you move from the other side to the one side in the first direction, in accordance with the change in the area of ​​the second upper electrode. Matching box.

2. A directional coupling circuit associated with the aforementioned high-frequency supply line, A matching control unit that controls the opening and closing of the plurality of relays based on the signal from the directional coupling circuit, The matching device according to claim 1, further comprising:

3. The number of relays connected to the first upper electrode and the number of relays connected to the second upper electrode are, respectively, 2 or more and 6 or less. Matching device according to claim 1 or 2.

4. The frequency of the aforementioned high-frequency power is 100 MHz or higher. Matching device according to claim 1 or 2.

5. The dielectric plate is First printed circuit board and A second printed circuit board is provided on the first printed circuit board, A dielectric layer interposed between the first printed circuit board and the second printed circuit board, Includes, The lower electrode is provided on the surface of the first printed circuit board facing the side opposite to the second printed circuit board. The plurality of first upper electrodes and the plurality of second upper electrodes are each provided on the surface of the second printed circuit board facing the side opposite to the first printed circuit board. Matching device according to claim 1 or 2.

6. Matching device according to claim 1 or 2, Chamber and, An introduction unit arranged to introduce electromagnetic waves into the plasma generation region within the chamber, High-frequency power supply and The high-frequency supply line electrically connected to the 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 plasma processing device equipped with the following features.

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