Matching device and plasma processing apparatus

Abstract

A matching device disclosed herein 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 a relay coil and a relay switch each having a first contact connected to each of the plurality of reactance elements. A second contact different from the first contacts of some relay switches among the plurality of relay switches is connected to the ground element. A third contact different from the first contacts of the remaining relay switches among the plurality of relay switches is connected to the inductor element and is 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.

Description

Matching unit and plasma processing unit

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

[0002] Patent Document 1 discloses an embodiment of a matching network including a switchable variable capacitor circuit. The switchable variable capacitor circuit includes between one 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. Changing 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.

[0003] Special Publication No. 2014-505983

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

[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 two 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 two as you move from the other direction to the one in the first direction, in accordance with the change in the area of ​​the second upper electrode.

[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.

[0007] This figure shows a plasma processing apparatus according to one exemplary embodiment. This figure shows the lower part of the resonator of the plasma processing apparatus according to one exemplary embodiment. This figure shows a matching circuit according to one exemplary embodiment. This is a schematic cross-sectional view of the matching circuit shown in Figure 3. This is an example of the equivalent circuit of an L-type matching circuit according to a comparative example, and the matching range of the load impedance at a frequency of 200 MHz calculated using the equivalent circuit. This figure shows a matching circuit according to another exemplary embodiment. This is a schematic cross-sectional view of the matching circuit shown in Figure 6.

[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 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 provided 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 manner. 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 waves 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 output high-frequency power. For example, the high-frequency power may be 100 MHz or higher. The electromagnetic wave is input to the power supply section 20p of the resonator 20 via a high-frequency supply line 40. The resonator 20 resonates the electromagnetic wave input to the power supply section 20p in 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 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 made of 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 is a diagram showing 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 layer structure and a lower part 20b constituting the lowest layer of the layer structure. The layer 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 a 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 a 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 positioned above the introduction section 16. The plurality of slots 14s electromagnetically couple the waveguide 20w and the introduction section 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 a plurality of gaps 20g, i.e., a plurality of 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 a signal 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 a signal from the directional coupler 31. The relay drive unit 34 generates a voltage to drive the relay coils based on the signal from the matching control unit 33.

[0032] Figure 3 shows a matching device according to one exemplary embodiment. Figure 4 is a schematic cross-sectional view of the matching device shown in Figure 3. As shown in Figures 3 and 4, the matching device 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 small dielectric loss tangent, such as tetrafluoroethylene.

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

[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, and a DC voltage signal can be applied from the relay drive unit 34 to set the state (open or closed) of the relay switch 61s.

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

[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 contacts 71b of the relay switches 71s of some of the plurality of relays RLA1 to RLA5 and RLB1 to RLB5, i.e., RLB1 to RLB5. The ground pattern 51 can be connected to the housing 30h via the metal support 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 contacts 61b of the relay switches 61s of the remaining relays RLA1 to RLA5 among the plurality of relays RLA1 to RLA5 and RLB1 to RLB5, i.e., RLA1 to RLA5. One end of the inductor pattern 52 can be connected to the output-side coaxial connector 40c.

[0038] The matcher 30 has a lower electrode 53, a plurality (in one example, 5) of first upper electrodes 54a, and a plurality (in one example, 5) of second upper electrodes 54b. Each of the lower electrode 53, the first upper electrodes 54a, and the second upper electrodes 54b is formed of a continuous single metal pattern (for example, 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 configured 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 electrode 54a is formed on the upper surface 50a of the printed circuit board 50. That is, the plurality of first upper electrodes 54a are provided on the printed circuit board 50 so as to face the lower electrode 53 via the printed circuit board 50, respectively. The plurality of first upper electrodes 54a are each connected to the first contact 61a of a relay switch 61s having a third contact 61b connected to the inductor pattern 52. The plurality of first upper electrodes 54a are arranged along a first direction D1 along the upper surface 50a.

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

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

[0043] Furthermore, in the matching unit 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, the second upper electrodes 54b with relatively large areas among the second upper electrodes 54b constituting capacitors CB1 to CB5 are positioned opposite the first upper electrodes 54a with relatively small areas among the first upper electrodes 54a constituting capacitors CA1 to CA5 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, which constitutes the capacitor CAN (n=1 to 5), and the second upper electrode 54b, which constitutes 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 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, if the capacitances of capacitors CA1 to CA5 are Cn = Cr × 2 （ｎ－１） For n=1 to N, the number of relays is N=log ２ The value becomes (Cm / Cr) + 1, which is the minimum value. Since the parasitic capacitance between the terminals of the capacitance variable section (for example, 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 has 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 are capacitors CA1 to CA5 and relays RLA1 to RLA5, and capacitors CB1 to CB5 and relays RLB1 to RLB5. As a result, there is no need for wiring between the capacitance variable sections, and parasitic inductance due to wiring can be minimized.

[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 becomes possible to handle 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 FIG. 5(a), 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] FIGS. 5(b) and 5(c) are the matching possible ranges (Smith charts) of load impedance at a frequency of 200 MHz calculated using the equivalent circuit of FIG. 5(a). In the calculation, the values of each reactance are set assuming a matching circuit using a relay. FIG. 5(b) shows 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). FIG. 5(c) shows the case where a 40 nH wiring is connected between the variable capacitance parts (L ｉｔ = 40 nH, L ｒｌ = 40 nH, L ｌｄ= 0 nH). 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 80 nH. The series inductance on the Tune side is 40 nH in the case of Figure 5(b) and 80 nH 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 it is at its minimum value (5 pF). To match a load impedance around 50 Ω, 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 41.5 Ω in Figure 5(b), compared to 29.9 Ω in Figure 5(c). In this way, by eliminating the wiring between the capacitance variable parts and reducing the series inductance on the Tune side, the matching range can be expanded.

[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 to N) can be set to 2 or more and 6 or less.

[0055] Figure 6 shows a matching circuit in 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 (for example, copper wire) connected to a 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] A plurality of reactance elements connected to a high-frequency supply line for high-frequency power for plasma generation; a plurality of relays including relay switches and relay coils, each having a first contact connected to each of the plurality of reactance elements; a ground element to which a second contact different from the first contact of the relay switch of some of the plurality of relays is connected; an inductor element to which a third contact different from the first contact of the relay switch of the remaining relays is connected and which is connected to the high-frequency supply line, wherein the plurality of reactance elements include a lower electrode consisting of a single continuous metal pattern; a dielectric plate formed on the lower electrode; and a plurality of first upper electrodes arranged along a first direction, provided on the dielectric plate so as to face the lower electrode via the dielectric plate, and connected to the first contact of the relay switch having a third contact connected to the inductor element, Matching circuit, comprising: a plurality of second upper electrodes arranged along the first direction, facing the first upper electrode in a second direction intersecting the first direction, wherein the plurality of first upper electrodes are arranged along the 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 side of the first direction to the other, in accordance with the change in the area of ​​the first upper electrode; and 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 power of 2 as you move from one side of the first direction to the other, in accordance with the change in the area of ​​the second upper electrode.

[0064] [E2] The matching device according to E1, further comprising: a directional coupling circuit connected to the high-frequency supply line; and a matching control unit that controls the opening and closing of the plurality of relays based on signals from the directional coupling circuit.

[0065] [E3] The matching device according to E1 or E2, wherein the number of relays connected to the first upper electrode and the number of relays connected to the second upper electrode are each 2 or more and 6 or less.

[0066] [E4] The matching circuit according to any one of E1 to E3, wherein the frequency of the high-frequency power is 100 MHz or higher.

[0067] [E5] The dielectric plate comprises a first printed circuit board, a second printed circuit board provided on the first printed circuit board, and a dielectric layer interposed between the first printed circuit board and the second printed circuit board, wherein the lower electrode is provided on the surface of the first printed circuit board facing away from the second printed circuit board, and 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 away from the first printed circuit board, the matching device according to any one of E1 to E4.

[0068] [E6] A plasma processing apparatus comprising: a matching unit according to any one of E1 to E5; a chamber; an introduction unit disposed to introduce electromagnetic waves into a plasma generation region within the chamber; a high-frequency power supply; a high-frequency supply line electrically connected to the high-frequency power supply; a power supply unit which is an inlet 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 resonator having a waveguide extending between the first end and the second end and electromagnetically coupled to the introduction unit.

[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.

[0070] 1...Plasma processing apparatus, 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. A plurality of reactance elements connected to a high-frequency supply line for high-frequency power for plasma generation; a plurality of relays including relay switches and relay coils, each having a first contact connected to each of the plurality of reactance elements; a ground element to which a second contact different from the first contact of the relay switch of some of the plurality of relays is connected; an inductor element to which a third contact different from the first contact of the relay switch of the remaining relays is connected and which is connected to the high-frequency supply line, wherein the plurality of reactance elements include a lower electrode consisting of a single continuous metal pattern; a dielectric plate formed on the lower electrode; and a plurality of first upper electrodes arranged along a first direction, provided on the dielectric plate so as to face the lower electrode via the dielectric plate, and connected to the first contact of the relay switch having a third contact connected to the inductor element, Matching circuit, comprising: a plurality of second upper electrodes arranged along the first direction, facing the first upper electrode in a second direction intersecting the first direction, wherein the plurality of first upper electrodes are arranged along the 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 side of the first direction to the other, in accordance with the change in the area of ​​the first upper electrode; and 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 power of 2 as you move from one side of the first direction to the other, in accordance with the change in the area of ​​the second upper electrode.

2. The matching device according to claim 1, further comprising: a directional coupling circuit connected to the high-frequency supply line; and a matching control unit that controls the opening and closing of the plurality of relays based on signals from the directional coupling circuit.

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

4. The matching circuit according to claim 1 or 2, wherein the frequency of the high-frequency power is 100 MHz or higher.

5. The dielectric plate comprises a first printed circuit board, a second printed circuit board provided on the first printed circuit board, and a dielectric layer interposed between the first printed circuit board and the second printed circuit board, wherein the lower electrode is provided on the surface of the first printed circuit board facing away from the second printed circuit board, and 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 away from the first printed circuit board, the matching device according to claim 1 or 2.

6. A plasma processing apparatus comprising: a matching unit according to claim 1 or 2; a chamber; an introduction unit disposed to introduce electromagnetic waves into a plasma generation region within the chamber; a high-frequency power supply; a high-frequency supply line electrically connected to the high-frequency power supply; and a resonator having a power supply unit which is an inlet 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 introduction unit.

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