Plasma processing apparatus

Abstract

This plasma processing apparatus comprises: an impedance matching circuit; a vacuum container; a first electrode, a second electrode, and a third electrode provided in the vacuum container; a 1:1-type float balun; an n2:1-type float balun (n being a natural number of 2 or more); a first terminal electrically connected to the first electrode; a second terminal electrically connected to the second electrode; and a third terminal electrically connected to the third electrode. A negative output terminal of a first power supply is electrically connected to the first terminal, a negative output terminal of a second power supply is electrically connected to the second terminal, and a positive output terminal of the first power supply and a positive output terminal of the second power supply are electrically connected to the third terminal. A current is supplied from the impedance matching circuit to the 1:1-type float balun, and a current is supplied from the 1:1-type float balun to the first electrode and the second electrode via the n2:1-type float balun.

Description

Plasma processing equipment

[0001] This invention relates to a plasma processing apparatus.

[0002] Patent Document 1 describes an impedance matching device inserted between a pair of electrodes and a power supply in a plasma reaction chamber. In the impedance matching device described in Patent Document 1, an impedance converter having an isolation function is placed between the pair of electrodes and the power supply, n ２ A Type 1 impedance converter is provided. According to Patent Document 1, the current flowing through the impedance matching device is reduced to 1 / n of the current flowing between the pair of electrodes, thereby suppressing heat generation in the impedance matching device and allowing power to be supplied to the plasma reaction chamber more efficiently.

[0003] However, in the impedance matching device described in Patent Document 1, the effect of load fluctuations between the pair of electrodes is greater than in an impedance matching device having a 1:1 type impedance converter.

[0004] Patent No. 2530560

[0005] This disclosure aims to provide a technique that is advantageous for reducing the effects of load fluctuations between a pair of electrodes while reducing the current flowing through an impedance matching circuit.

[0006] One aspect of the present disclosure relates to a plasma processing apparatus, the plasma processing apparatus comprising an impedance matching circuit, a vacuum vessel, a first electrode, a second electrode and a third electrode provided in the vacuum vessel, a 1:1 type float balun, and n ２ The 1:1 type float balun comprises a 1:1 type float balun (where n is a natural number of 2 or more), a first terminal electrically connected to the first electrode, a second terminal electrically connected to the second electrode, and a third terminal electrically connected to the third electrode, wherein the negative output terminal of the first power supply is electrically connected to the first terminal, the negative output terminal of the second power supply is electrically connected to the second terminal, and the positive output terminals of the first and second power supplies are electrically connected to the third terminal, current is supplied from the impedance matching circuit to the 1:1 type float balun, and current is supplied from the 1:1 type float balun to the n２ Current is supplied to the first electrode and the second electrode via a Type 1 float balun.

[0007] A diagram illustrating the configuration of a voltage-type balun. A diagram illustrating the configuration of a current-type balun. A diagram showing an example configuration of a plasma processing apparatus having a float balun. A diagram for explaining the operation of a plasma processing apparatus having a float balun. A diagram illustrating the relationship between currents I1 (=I2), I2', I3, ISO, α (=X / Rp), and phase difference. A diagram illustrating the relationship between ISO and α (=X / Rp). A diagram showing an example configuration of a plasma processing apparatus equipped with a 1:1 type float balun. A diagram showing an example configuration of a plasma processing apparatus equipped with a 4:1 type float balun. A diagram illustrating the calculation results of the voltage ratio between the first electrode and the second electrode. A diagram schematically showing the configuration of the plasma processing apparatus of the first embodiment. A diagram showing the calculation results of the performance of the plasma processing apparatus for various float balun specifications with the same total number of coil turns. A diagram illustrating the relationship between the combined impedance of the float balun and the performance (voltage ratio) of the plasma processing apparatus. A diagram showing a comparative example in which the plasma processing apparatus shown in Figure 8 is materialized as a sputtering apparatus. Figure 10 shows an example of a plasma processing apparatus according to the first embodiment as a sputtering apparatus. Figure 13 illustrates the change in voltage of the first electrode and the second electrode when the pressure in the internal space of the vacuum vessel is changed in the sputtering apparatus according to the comparative example shown. Figure 14 shows the change in voltage of the first electrode E1 and the second electrode E2 when the pressure in the internal space of the vacuum vessel is changed in the sputtering apparatus according to the second design example of the first embodiment shown. Graph plotting the results of Figure 15 (comparative example) and Figure 16 (second design example). Diagram schematically showing the configuration of the plasma processing apparatus of the second embodiment. Diagram illustrating the adjustment of the voltage between the first electrode and the second electrode by an adjustment circuit. Diagram schematically showing the configuration of the plasma processing apparatus of the third embodiment. Diagram for explaining the connection relationship between a 1:1 type float balun and a 4:1 type float balun in the float balun shown in Figure 10. Diagram explaining an example. Diagram explaining an example. Diagram explaining an example. Diagram schematically showing the configuration of the plasma processing apparatus of the fourth embodiment. A schematic diagram showing the configuration of the plasma processing apparatus according to the fifth embodiment.

[0008] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the scope of the claims. While the embodiments describe multiple features, not all of these features are necessary, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0009] First, let's explain baluns. A balun is a balance-to-unbalance conversion circuit. There are two types of baluns: voltage-type baluns, as illustrated in Figure 1, and current-type baluns, as illustrated in Figure 2. In a voltage-type balun, the pair of unbalanced output voltages of a high-frequency power supply RF are divided into two by coils C1 and C2, and a voltage equal to the divided voltage is induced in coil C3. This allows a balanced voltage to be supplied to the load with the ground potential as the neutral point. On the other hand, in a current-type balun, the pair of unbalanced output voltages of a high-frequency power supply RF are supplied to the input terminals of coils C1 and C2, respectively, and currents flow in opposite directions through coils C1 and C2, which are then supplied to the load. Current-type baluns are also called float baluns. The balun described below is a float balun.

[0010] The isolation function of the float balun will be described below with reference to Figures 3, 4, 5, and 6. Figure 3 schematically shows the configuration of a plasma processing apparatus 1 having a float balun BL. The plasma processing apparatus 1 may include, for example, a high-frequency power supply RF, an impedance matching circuit MB, a float balun BL, a blocking capacitor BC1, a vacuum vessel CH, a first electrode E1, and a second electrode E2. The first electrode E1 and the second electrode E2 are provided in the vacuum vessel CH and generate plasma in the internal space of the vacuum vessel CH by supplying high-frequency power to the internal space of the vacuum vessel CH. The vacuum vessel CH may be grounded. The first electrode E1 and the second electrode E2 may be arranged in the internal space of the vacuum vessel CH, or they may define the internal space together with the vacuum vessel CH, as illustrated in Figure 3. The first electrode E1 and the second electrode E2 may be supported by the vacuum vessel CH via an insulator INS, for example. In the example shown in Figure 3, the target T is held by the first electrode E1 and the substrate S is held by the second electrode E2, and the plasma processing apparatus 1 is configured as a sputtering apparatus. However, the plasma processing apparatus 1 may also be configured as an etching apparatus for etching the substrate S.

[0011] A float balun BL may have a first unbalanced terminal IN1, a second unbalanced terminal IN2, a first balanced terminal OUT1, and a second balanced terminal OUT2. A float balun BL may have a first coil C1 connecting the first unbalanced terminal IN1 and the first balanced terminal OUT1, and a second coil C2 connecting the second unbalanced terminal IN2 and the second balanced terminal OUT2. A float balun BL having such a configuration is called a 1:1 type float balun. The output of the impedance matching circuit MB may be electrically connected to the first unbalanced terminal IN1 of the float balun BL. The second unbalanced terminal IN2 of the float balun BL may be grounded. The first balanced terminal OUT1 of the float balun BL may be electrically connected to the first electrode E1 via a blocking capacitor BC1. The second balanced terminal OUT2 of the float balun BL may be electrically connected to the second electrode E2.

[0012] Let I1 be the current flowing through the first unbalanced terminal IN1, I2 be the current flowing through the first balanced terminal OUT1, I2' be the current flowing through the second unbalanced terminal IN2, and I3 be the current of I2 that flows to ground. When I3 = 0, that is, when no current flows to ground on the balanced circuit side, the isolation performance of the balanced circuit with respect to ground is best. When I3 = I2, that is, when all of the current I2 flowing through the first balanced terminal OUT1 flows to ground, the isolation performance of the balanced circuit with respect to ground is worst. An index ISO indicating the degree of such isolation performance can be given by the following formula. Under this definition, a larger absolute value of ISO indicates better isolation performance.

[0013] ISO [dB] = 20log(I3 / I2') In Figure 4, Rp - jXp represents the impedance (including the reactance of the blocking capacitor BC1) when viewed from the side of the first equilibrium terminal OUT1 and the second equilibrium terminal OUT2 towards the side of the first electrode E1 and the second electrode E2, with plasma generated in the internal space of the vacuum vessel CH. Rp represents the resistance component, and -Xp represents the reactance component. Also in Figure 4, X represents the reactance component (inductance component) of the impedance of the first coil C1 of the float balun BL. ISO is correlated with X / Rp. Figure 5 illustrates the relationship between current I1 (=I2), I2', I3, ISO, α (=X / Rp), and phase difference. Figure 6 illustrates the relationship between ISO and α (=X / Rp). The phase difference is the phase difference between the current output from the first balanced terminal OUT1 and the current output from the second balanced terminal OUT2.

[0014] The following explains the relationship between the configuration of the float balun BL and the performance of the plasma processing device 1.

[0015] Figure 7 schematically shows the configuration of a plasma processing apparatus 1 equipped with a 1:1 type float balun BL as the float balun. In the example shown in Figure 7, the first balance terminal OUT1 of the float balun BL and the first electrode E1 are electrically connected by a first transmission line TL1 having a first inductance TLL1. Also in the example shown in Figure 7, the second balance terminal OUT2 of the float balun BL and the second electrode E2 are electrically connected by a second transmission line TL2 having a second inductance TLL2. Furthermore, a first blocking capacitor BC1 may be placed in the first transmission line TL1. A second blocking capacitor BC2 may be placed in the second transmission line TL2.

[0016] In Figure 7, Rp - jXp (= Rp / 2 - jXp / 2 + Rp / 2 - jXp / 2) represents the plasma impedance between the first electrode E1 and the second electrode E2 (and within the internal space of the vacuum vessel CH) when plasma is generated in the internal space of the vacuum vessel CH. Rp represents the resistance component, and -Xp represents the reactance component. Hereafter, Xp will also be referred to as plasma impedance. In Figure 7, X represents the reactance component (inductance component) of the impedance of the first coil C1 of the float balun BL.

[0017] Figure 8 schematically shows the configuration of a plasma processing apparatus 1 equipped with a 4:1 type float balun as the float balun BL. The configuration shown in Figure 8 is the same as the configuration shown in Figure 7, but with the 1:1 type float balun replaced by a 4:1 type float balun. Note that the 4:1 type float balun is n ２ : This is an example of a Type 1 float balun. In this specification, n ２ : A type 1 float balun is a natural number n greater than or equal to 2. ２ : This refers to a type 1 float balun and does not include a 1:1 type float balun. Patent Document 1 contains n ２ A configuration having a Type 1 impedance converter (float balun) is shown.

[0018] A configuration using a 4:1 floating balun as the floating balun BL is advantageous for reducing the current flowing through the floating balun BL. Specifically, in a configuration using a 4:1 floating balun as the floating balun BL, the current flowing through the floating balun BL is 1 / 4 of the current flowing through the floating balun BL in a configuration using a 1:1 floating balun as the floating balun BL.

[0019] However, for a configuration using a 4:1 floating balun (n ２ :1 floating balun), the voltage ratio between the first electrode E1 and the second electrode E2 (the ratio of the voltage of the first electrode E1 to the voltage of the second electrode E2) is larger than that in a configuration using a 1:1 floating balun with the same total number of turns. Similarly, for a configuration using a 4:1 floating balun (n ２ :1 floating balun), the current ratio between the first electrode E1 and the second electrode E2 (the ratio of the current flowing through the first electrode E1 to the current flowing through the second electrode E2) is larger than that in a configuration using a 1:1 floating balun with the same total number of turns.

[0020] FIG. 9 exemplifies the calculation result of the voltage ratio between the first electrode E1 and the second electrode E2. In FIG. 9, "4:1" indicates the voltage ratio (the ratio of the voltage of the first electrode E1 to the voltage of the second electrode E2) in the configuration using a 4:1 floating balun, and "1:1" indicates the voltage ratio (the ratio of the voltage of the first electrode E1 to the voltage of the second electrode E2) in the configuration using a 1:1 floating balun. Note that, in order to unify the comparison criteria, calculation was performed with the total number of turns of the four coils constituting the 4:1 floating balun being the same as the total number of turns of the four coils constituting the 1:1 floating balun.

[0021] It can be seen that in the configuration using a 4:1 type float balance, the voltage ratio between the first electrode E1 and the second electrode E2 (the ratio of the voltage of the first electrode E1 to the voltage of the second electrode E2) is larger than that in the configuration using a 1:1 type float balance. Here, the voltage ratio between the first electrode E1 and the second electrode E2 increases correspondingly as the amount of change in the plasma impedance Xp increases. Although not shown in FIG. 9, in the configuration using a 4:1 type float balance, the calculation result of the current ratio between the first electrode E1 and the second electrode E2 (the ratio of the current flowing through the first electrode E1 to the current flowing through the second electrode E2) is the same as the calculation result of the voltage ratio. Changes in the plasma impedance Xp can be caused by, for example, changes in applied power, changes in the pressure of the vacuum vessel, changes in gas type, and the like.

[0022] Here, the voltage ratio and the current ratio can be defined as follows.

[0023] Voltage ratio = (V1-V2) / ((V1+V2) / 2) Current ratio = (I1-I2) / ((I1+I2) / 2) V1 is the voltage of the first electrode E1, V2 is the voltage of the second electrode E2, I1 is the current flowing through the first electrode E1, and I2 is the current flowing through the second electrode E2. As is clear from FIG. 9, the voltage ratio when using a 4:1 type float balance is significantly larger than the voltage ratio when using a 1:1 type float balance.

[0024] FIG. 10 schematically shows the configuration of the plasma processing apparatus 1 according to the first embodiment. In the configuration shown in FIG. 10, the floating balun BL in the configuration shown in FIG. 7 or FIG. 8 is replaced by a combination of a 1:1 type floating balun BL1 and a 4:1 type floating balun BL2, and the configuration additionally includes a first terminal TM1 for electrically connecting a first power supply PS1 to a first electrode E1, and a second terminal TM2 for electrically connecting a second power supply PS2 to a second electrode E2. The first power supply PS1 and the second power supply PS2 may be understood as external devices of the plasma processing apparatus 1, or may be understood as part of the plasma processing apparatus 1. The first power supply PS1 and the second power supply PS2 respectively supply voltages to be superimposed on the voltages of the first electrode E1 and the second electrode E2 to the first electrode E1 and the second electrode E2, respectively. The first power supply PS1 and the second power supply PS2 may be direct current power supplies. The direct current power supply may be a power supply that continuously outputs a set voltage, may be a pulsed DC power supply, may be a HiPIMS (High Power Impulse Magnetron Sputtering) power supply, or may be another power supply.

[0025] The plasma processing apparatus 1 may have an additional electrode E4. The additional electrode E4 can be driven by a power supply such as a direct current or alternating current power supply. Driving the additional electrode E4 by a power supply is advantageous for confining plasma in a restricted space. The plasma processing apparatus 1 may further include a second high-frequency power supply RF2 and a second impedance matching circuit MB2 for driving the additional electrode E4. Hereinafter, for distinction from the second high-frequency power supply RF2 and the second impedance matching circuit MB2, the aforementioned high-frequency power supply RF and impedance matching circuit MB are read as the first high-frequency power supply RF1 and the first impedance matching circuit MB1. A current is supplied from the first impedance matching circuit MB1 to the 1:1 type floating balun BL1, and a current is supplied from the 1:1 type floating balun BL1 to the first electrode E1 and the second electrode E2 via the 4:1 type floating balun BL2. In other words, the 1:1 type floating balun BL1 is arranged between the first impedance matching circuit MB1 and the 4:1 type floating balun BL2.

[0026] The additional electrode E4 is provided in the vacuum chamber CH. In the example shown in Figure 10, current is supplied to the additional electrode E4 from the second impedance matching circuit MB2. In another view, current is supplied to the additional electrode E4 from the second high-frequency power supply RF2 via the second impedance matching circuit MB2. By supplying a high-frequency current to the additional electrode E4 from the second high-frequency power supply RF2 via the second impedance matching circuit MB2, the self-bias voltage generated at the additional electrode E4 can be stabilized. This is advantageous for improving the reproducibility of plasma processing.

[0027] Figure 21 is a diagram illustrating the connection relationships between the 1:1 type float balun BL1 and the 4:1 type float balun BL2 in the float balun BL shown in Figure 10. The 1:1 type float balun BL1 has a first input terminal IT1, a second input terminal IT2, a first output terminal OT1, a second output terminal OT2, a first coil C1 that electrically connects the first input terminal IT1 and the first output terminal OT1, and a second coil C2 that electrically connects the second input terminal IT2 and the second output terminal OT2. The 4:1 type float balun BL2 has a third input terminal IT3, a fourth input terminal IT4, a third output terminal OT3, a fourth output terminal OT4, a third coil C3 connecting the third input terminal IT3 and the third output terminal OT3, a fourth coil C4 connecting the fourth input terminal IT4 and the fourth output terminal OT4, and a fifth coil C5 and a sixth coil C6 connecting the third output terminal OT3 and the fourth output terminal OT4. The first input terminal IT1 is the first unbalanced terminal IN1, and the second input terminal IT2 is the second unbalanced terminal IN2. The third output terminal OT3 is the first balanced terminal OUT1, and the fourth output terminal OT4 is the second balanced terminal OUT2.

[0028] The first output terminal OT1 and the third input terminal IT3 are electrically connected, and the second output terminal OT2 and the fourth input terminal IT4 are electrically connected. The third output terminal OT3 and the first electrode E1 may be electrically connected by a first transmission line TL1 having a first inductance TLL1 (inductance component). The fourth output terminal OT4 and the second electrode E2 may be electrically connected by a second transmission line TL2 having a second inductance TLL2. A reactance such as a first blocking capacitor BC1 may or may not be placed in the first transmission line TL1. A reactance such as a second blocking capacitor BC2 may or may not be placed in the second transmission line TL2. The absolute value of the first inductance TLL1 (inductance component) may be greater than the absolute value of the capacitance of the first blocking capacitor BC1. The absolute value of the second inductance TLL2 (inductance component) may be greater than the absolute value of the capacitance of the second blocking capacitor BC2.

[0029] As shown in Figures 5 and 6, X / Rp correlates with ISO and also with the phase difference. In the state with the best isolation performance, the phase difference between the current supplied to the first electrode E1 and the current supplied to the second electrode E2 is 180 degrees. While it is ideal for the substrate S to be processed in this state, a phase difference of 171 degrees or more between the current supplied to the first electrode E1 and the current supplied to the second electrode E2 is practical. In other words, the phase difference may be between 171 degrees and 180 degrees.

[0030] Figure 11 shows the calculated performance of the plasma processing apparatus 1 for various float balun BL specifications with the same total number of coil turns. In Figure 11, the horizontal axis represents the change in plasma impedance Xp, and the vertical axis represents the calculated voltage ratio between the first electrode E1 and the second electrode E2. Although not shown in Figure 11, the calculated current ratio between the first electrode E1 and the second electrode E2 is similar to the calculated voltage ratio between the first electrode E1 and the second electrode E2.

[0031] In Figure 11, the square represents the performance of the plasma processing apparatus 1 in a comparative example where the float balun BL is composed solely of a 4:1 type float balun, as shown in Figure 8. In the comparative example, the inductance of each coil constituting the 4:1 type float balun is 125 Ω.

[0032] In Figure 11, the triangle represents a first design example in which the float balun BL is composed of a 1:1 type float balun BL1 and a 4:1 type float balun BL2, as shown in Figure 10. In the first design example, the inductance X1 of each coil constituting the 1:1 type float balun BL1 is 50Ω, and the inductance X2 of each coil constituting the 4:1 type float balun BL2 is 100Ω. In this case, the combined impedance X of the 1:1 type float balun BL1 is １：１ X1 / 2 = 25Ω, and a 4:1 type float balun (n ２ (Type 1 float balun) Combined impedance X of BL2 ４：１ X² / 4 = 25Ω. Also, the combined impedance of the float balun BL, which consists of a 1:1 type float balun BL1 and a 4:1 type float balun BL2, is X. ＢＬ The ratio is X1 / 2 + X2 / 4 = 50Ω / 2 + 100Ω / 4 = 50Ω. In this example, X １：１ ≥X ＢＬ >X ４：１ This satisfies the following conditions: 1:1 type float balun BL1 and n ２ The combined impedance of the float balun BL, which consists of a type 1 float balun BL2, is less than or equal to the combined impedance of a 1:1 type float balun, n ２ : Greater than the combined impedance of a Type 1 float balun. １：１ ≥X ＢＬ >X ４：１ Satisfying this condition is advantageous in order to limit the increase in the dimensions of the float balun BL while keeping the voltage and current ratios due to fluctuations in the plasma impedance Xp small.

[0033] Note that the combined impedance X of the 1:1 type float balun BL1 is １：１This is the impedance between the first input terminal IT1 and the first output terminal OT1 in Figure 21, and if X1 is the inductance of each coil constituting the 1:1 type float balun BL1, then it is X1 / 2. 4:1 type float balun (n ２ (Type 1 float balun) Combined impedance X of BL2 ４：１ This is the impedance between the third input terminal IT3 and the third output terminal OT3 in Figure 21, and is X2 / 4, where X2 is the inductance of each coil constituting the 4:1 type float balun BL2.

[0034] In Figure 11, the diamond shape represents a second design example in which the float balun BL is composed of a 1:1 type float balun BL1 and a 4:1 type float balun BL2, as shown in Figure 10. In the second design example, the inductance X1 of each coil constituting the 1:1 type float balun BL1 is 100Ω, and the inductance X2 of each coil constituting the 4:1 type float balun BL2 is 75Ω. In this case, the combined impedance X of the 1:1 type float balun BL1 is... １：１ X1 / ==50Ω, and a 4:1 type float balun (n ２ (Type 1 float balun) Combined impedance X of BL2 ４：１ The impedance is X² / 4 = 18.8Ω. Also, the combined impedance of the entire float balun BL, which consists of a 1:1 type float balun BL1 and a 4:1 type float balun BL2, is X. ＢＬ The resistance is X1 / 2 + X2 / 4 = 100Ω / 2 + 75Ω / 4 = 68.8Ω. In this example, X １：１ ≥X ＢＬ >X ４：１ It satisfies the condition.

[0035] In Figure 11, the circle represents a third design example in which the float balun BL is composed of a 1:1 type float balun BL1 and a 4:1 type float balun BL2, as shown in Figure 10. In the third design example, the inductance X1 of each coil constituting the 1:1 type float balun BL1 is 150Ω, and the inductance X2 of each coil constituting the 4:1 type float balun BL2 is 50Ω. In this case, the combined impedance X of the 1:1 type float balun BL1 is １：１ X1 / 2 = 75Ω, and a 4:1 type float balun (n２ (Type 1 float balun) Combined impedance X of BL2 ４：１ The impedance is X² / 4 = 12.5Ω. Also, the combined impedance of the entire float balun BL, which consists of a 1:1 type float balun BL1 and a 4:1 type float balun BL2, is X. ＢＬ The resistance is X1 / 2 + X2 / 4 = 150Ω / 2 + 50Ω / 4 = 87.5Ω. In this example, X １：１ ≥X ＢＬ >X ４：１ This satisfies the condition. From Figure 11, it can be seen that the voltage ratios in the first, second, and third design examples are smaller than the voltage ratios in the comparative example.

[0036] In the comparative example, the combined impedance of the float balun BL is 125Ω / 4 = 31.3Ω. In the first design example, the combined impedance of the float balun BL is 50Ω / 2 + 100Ω / 4 = 50Ω. In the second design example, the combined impedance of the float balun BL is 100Ω / 2 + 75Ω / 4 = 68.8Ω. In the third design example, the combined impedance of the float balun BL is 150Ω / 2 + 50Ω / 4 = 87.5Ω. Figure 12 shows the relationship between the combined impedance of the float balun BL and the performance (voltage ratio) of the plasma processing apparatus 1. Each point in Figure 12 shows the relationship between the voltage ratio and the combined impedance of the float balun BL when the change in plasma impedance Xp in Figure 11 is 5Ω. From Figure 12, it can be seen that the larger the combined impedance of the float balun BL, the smaller the voltage ratio.

[0037] Figure 13 shows a comparative example in which the plasma processing apparatus 1 shown in Figure 8 is implemented as a sputtering apparatus. A first target T1 may be attached to the first electrode E1, and a second target T2 may be attached to the second electrode E2. An additional electrode E4 may constitute at least a part of the substrate holding portion that holds the substrate S to be processed. The additional electrode E4 may be positioned opposite the first electrode E1 and the second electrode E2. The plasma processing apparatus 1 may include a rotation mechanism RM for rotating the substrate holding portion or the additional electrode E4. The first electrode E1 and the second electrode E2 may be positioned higher than the additional electrode E4, which constitutes at least a part of the substrate holding portion. The second electrode E2 may be positioned to the side of the first electrode E1. In one example, the surfaces of the first electrode E1 and the second electrode E2 may be positioned to belong to a single plane, and the substrate holding portion or the additional electrode E4 may be configured such that the surface of the substrate S is positioned parallel to that plane. Alternatively, the first electrode E1 may be positioned such that the normal of the surface of the first electrode E1 points toward the substrate S, and the second electrode E2 may be positioned such that the normal of the surface of the second electrode E2 points toward the substrate S. First high-frequency power may be supplied to the first electrode E1 and the second electrode E2 from the first high-frequency power supply RF1 via the first impedance matching circuit MB1 and the float balun BL (4:1 type float balun). Second high-frequency power may be supplied to the additional electrode E4 from the second high-frequency power supply RF2 via the second impedance matching circuit MB2. As a result, plasma is generated in the internal space of the vacuum vessel CH, and a film is formed on the substrate S by particles generated by sputtering of targets T1 and T2.

[0038] Figure 14 shows an example in which the plasma processing apparatus 1 according to the first embodiment shown in Figure 10 is implemented as a sputtering apparatus. A first target T1 may be attached to the first electrode E1, and a second target T2 may be attached to the second electrode E2. A first power supply PS1 may be electrically connected to the first terminal TM1, and a second power supply PS2 may be electrically connected to the second terminal TM2. The additional electrode E4 may constitute at least a part of the substrate holding portion that holds the substrate S to be processed. The plasma processing apparatus 1 may also include a rotation mechanism RM for rotating the substrate holding portion or the additional electrode E4. The additional electrode E4 may be arranged to face the first electrode E1 and the second electrode E2. The first electrode E1 and the second electrode E2 may be positioned higher than the additional electrode E4, which constitutes at least a part of the substrate holding portion, for example. The second electrode E2 may be positioned to the side of the first electrode E1. In one example, the surfaces of the first electrode E1 and the second electrode E2 may be arranged to belong to a single plane, and the substrate holder or additional electrode E4 may be configured such that the surface of the substrate S is parallel to the said plane. Alternatively, the first electrode E1 may be arranged such that the normal of the surface of the first electrode E1 points toward the substrate S, and the second electrode E2 may be arranged such that the normal of the surface of the second electrode E2 points toward the substrate S.

[0039] A first high-frequency power can be supplied from a first high-frequency power supply RF1 to the first electrode E1 and the second electrode E2 via a first impedance matching circuit MB1 and a float balun BL (1:1 type float balun BL1 + 4:1 type float balun BL2). In addition, a second high-frequency power can be supplied from a second high-frequency power supply RF2 to an additional electrode E4 via a second impedance matching circuit MB2. This generates plasma in the internal space of the vacuum vessel CH, and a film is formed on the substrate S by particles generated by sputtering of targets T1 and T2. The frequency of the first high-frequency power generated by the first high-frequency power supply RF1 can be selected, for example, in the range of 1 MHz or more and 100 MHz or less. The frequency of the second high-frequency power generated by the second high-frequency power supply RF2 can be selected, for example, in the range of 1 MHz or more and 100 MHz or less. In one example, the frequency of the first high-frequency power generated by the first high-frequency power supply RF1 may be 27.12 MHz, and the frequency of the second high-frequency power generated by the second high-frequency power supply RF2 may be 13.56 MHz.

[0040] Figure 15 shows the voltage changes at the first electrode E1 and the second electrode E2 when the pressure inside the vacuum vessel CH is changed in the sputtering apparatus according to the comparative example shown in Figure 13. The frequency of the first high-frequency power supply RF1 is 27.12 MHz, and the applied power of the first high-frequency power supply RF1 is 3000 W. The inductance of each coil constituting the 4:1 type float balun is 125 Ω. Targets T1 and T2 are alumina targets. For simplification, the applied power of the second high-frequency power supply RF2 is set to 0 W.

[0041] Figure 16 shows the voltage changes at the first electrode E1 and the second electrode E2 when the pressure in the internal space of the vacuum vessel CH is changed in the sputtering apparatus according to the second design example of the first embodiment shown in Figure 14. The frequency of the first high-frequency power supply RF1 is 27.12 MHz, and the applied power of the first high-frequency power supply RF1 is 3000 W. The inductance of each coil constituting the 1:1 type float balun BL1 is 100 Ω, and the inductance of each coil constituting the 4:1 type float balun BL2 is 75 Ω. Targets T1 and T2 are alumina targets. For simplification, the applied power of the second high-frequency power supply RF2 is set to 0 W, and the first power supply PS1 and the second power supply PS2 are not connected to the first terminal TM1 and the second terminal TM2.

[0042] Figure 17 is a graph plotting the results of Figure 15 (Comparative Example) and Figure 16 (Second Design Example). When the pressure is changed from 0.1 Pa to 1.0 Pa, the change in the voltage ratio is 2.1% in Figure 15 (Comparative Example), while in Figure 16 (Second Design Example), the change is reduced to 1.0%. In other words, a 53% improvement in characteristics is observed in Figure 16 (Second Design Example) compared to Figure 15 (Comparative Example). This is consistent with the results shown in Figure 11 (square (Comparative Example), rhombus (Second Design Example)).

[0043] A method of processing a substrate S using the plasma processing apparatus 1 of the first embodiment can be understood as a plasma processing method. The plasma processing method may include, for example, a holding step of holding the substrate S by a substrate holding part or an additional electrode E4 in a vacuum chamber CH, and a processing step of generating plasma by supplying first high-frequency power between a first electrode E1 and a second electrode E2 through a first impedance matching circuit MB1 and a float balun BL, and processing the substrate S with this plasma.

[0044] In the processing step, a first voltage may be supplied to the first terminal TM1 from a first power supply PS1, and a second voltage may be supplied to the second terminal TM2 from a second power supply PS2. In the processing step, an additional electrode E4 may be driven through a second impedance matching circuit MB2. The plasma processing method may further include a preparation step of attaching a first target T1 made of a first material to the first electrode E1 and a second target T2 made of a second material different from the first material to the second electrode E2. The holding step and the processing step are performed after the preparation step. The composition of the film formed on the substrate S can be adjusted by adjusting the voltage supplied to the first electrode E1 by the first power supply PS1 via the first terminal TM1 and the voltage supplied to the second electrode E2 by the second power supply PS2 via the second terminal TM2. In other words, the composition ratio of the film formed on the substrate S can be adjusted by adjusting the ratio of the voltage supplied to the first electrode E1 by the first power supply PS1 via the first terminal TM1 and the voltage supplied to the second electrode E2 by the second power supply PS2 via the second terminal TM2. That is, the ratio of the voltage supplied to the first electrode E1 and the voltage supplied to the second electrode E2 should be determined according to the composition ratio of the film to be formed on the substrate S.

[0045] Alternatively, the composition of the film formed on the substrate S can be adjusted by adjusting the power supplied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the power supplied by the second power supply PS2 to the second electrode E2 via the second terminal TM2. In other words, the composition ratio of the film formed on the substrate S can be adjusted by adjusting the ratio of the power supplied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the power supplied by the second power supply PS2 to the second electrode E2 via the second terminal TM2. That is, the ratio of the power supplied to the first electrode E1 and the power supplied to the second electrode E2 should be determined according to the composition ratio of the film to be formed on the substrate S.

[0046] Alternatively, the composition of the film formed on the substrate S can be adjusted by adjusting the current supplied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the current supplied by the second power supply PS2 to the second electrode E2 via the second terminal TM2. In other words, the composition ratio of the film formed on the substrate S can be adjusted by adjusting the ratio of the current supplied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the current supplied by the second power supply PS2 to the second electrode E2 via the second terminal TM2. That is, the ratio of the current supplied to the first electrode E1 and the current supplied to the second electrode E2 should be determined according to the composition ratio of the film to be formed on the substrate S.

[0047] Figure 18 schematically shows the configuration of the plasma processing apparatus 1 of the second embodiment. In addition to the configuration of the plasma processing apparatus 1 of the first embodiment, the plasma processing apparatus 1 of the second embodiment may include an adjustment circuit VADJ for adjusting the voltage between the first electrode E1 and the second electrode E2. The adjustment circuit VADJ may include, for example, a first adjustment inductance AL1 and a first adjustment capacitance VC1 arranged in the first transmission line TL1, and a second adjustment inductance AL2 and a second adjustment capacitance VC2 arranged in the second transmission line TL2.

[0048] The adjustment capacitances VC1 and VC2 may be variable capacitances, and the voltage between the first electrode E1 and the second electrode E2 can be adjusted by adjusting the value of the variable capacitance. Figure 19 illustrates the adjustment of the voltage between the first electrode E1 and the second electrode E2 by the adjustment circuit VADJ. The voltage of the first electrode E1 can be evaluated, for example, as the peak value of the waveform obtained by half-wave rectifying the voltage waveform of the first electrode E1. Similarly, the voltage of the second electrode E2 can be evaluated, for example, as the peak value of the waveform obtained by half-wave rectifying the voltage waveform of the second electrode E2.

[0049] The plasma processing apparatus 1 of the second embodiment may include a first detection circuit VS1 for detecting the voltage of the first electrode E1 and a second detection circuit VS2 for detecting the voltage of the second electrode E2. The adjustment circuit VADJ can adjust the voltage between the first electrode E1 and the second electrode E2 to match a target voltage based on the voltage of the first electrode E1 detected by the first detection circuit VS1 and the voltage of the second electrode E2 detected by the second detection circuit VS2.

[0050] The adjustment circuit VADJ may have a mode of operation that adjusts the plasma so that it alternately repeats between a first state in which the voltage of the first electrode E1 is higher than the voltage of the second electrode E2, and a second state in which the voltage of the first electrode E1 is lower than the voltage of the second electrode E2. This mode contributes to stably controlling the plasma by confining it to a limited range. Furthermore, the composition of the film formed on the substrate S can be adjusted by adjusting the voltage supplied to the first electrode E1 by the first power supply PS1 via the first terminal TM1 and the voltage supplied to the second electrode E2 by the second power supply PS2 via the second terminal TM2. In addition, supplying a high-frequency current to the additional electrode E4 from the second high-frequency power supply RF2 via the second impedance matching circuit MB2 is advantageous for further confining the plasma to a limited range.

[0051] A method for processing a substrate S using the plasma processing apparatus 1 of the second embodiment can be understood as a plasma processing method. The plasma processing method may include, for example, a holding step of holding the substrate S by a substrate holding part or an additional electrode E4 in a vacuum chamber CH, and a processing step of generating plasma by supplying first high-frequency power between a first electrode E1 and a second electrode E2 through a first impedance matching circuit MB1 and a float balun BL, and processing the substrate S with this plasma.

[0052] In the processing step, a first voltage may be supplied to the first terminal TM1 from a first power supply PS1, and a second voltage may be supplied to the second terminal TM2 from a second power supply PS2. In addition, in the processing step, an additional electrode E4 may be driven through a second impedance matching circuit MB2. Driving the additional electrode E4 through the second impedance matching circuit MB2 is advantageous for homogenizing the composition of the film formed on the substrate S within the plane of the substrate S. The plasma processing method may include, for example, a step of processing the substrate S while alternately repeating a first state in which the voltage of the first electrode E1 is higher than the voltage of the second electrode E2, and a second state in which the voltage of the first electrode E1 is lower than the voltage of the second electrode E2. In this step, the voltages of the first electrode E1 and the second electrode E2 may be controlled so that the plasma is confined to a limited range.

[0053] The plasma processing method may further include a preparation step of attaching a first target T1 made of a first material to a first electrode E1 and a second target T2 made of a second material different from the first material to a second electrode E2. The holding step and the processing step are performed after the preparation step. The composition of the film formed on the substrate S can be adjusted by adjusting the voltage supplied to the first electrode E1 by the first power supply PS1 via the first terminal TM1 and the voltage supplied to the second electrode E2 by the second power supply PS2 via the second terminal TM2. In other words, the composition ratio of the film formed on the substrate S can be adjusted by adjusting the ratio of the voltage supplied to the first electrode E1 by the first power supply PS1 via the first terminal TM1 and the voltage supplied to the second electrode E2 by the second power supply PS2 via the second terminal TM2. That is, the ratio of the voltage supplied to the first electrode E1 and the voltage supplied to the second electrode E2 should be determined according to the composition ratio of the film to be formed on the substrate S.

[0054] Alternatively, the composition of the film formed on the substrate S can be adjusted by adjusting the power supplied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the power supplied by the second power supply PS2 to the second electrode E2 via the second terminal TM2. In other words, the composition ratio of the film formed on the substrate S can be adjusted by adjusting the ratio of the power supplied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the power supplied by the second power supply PS2 to the second electrode E2 via the second terminal TM2. That is, the ratio of the power supplied to the first electrode E1 and the power supplied to the second electrode E2 should be determined according to the composition ratio of the film to be formed on the substrate S.

[0055] Alternatively, the composition of the film formed on the substrate S can be adjusted by adjusting the current supplied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the current supplied by the second power supply PS2 to the second electrode E2 via the second terminal TM2. In other words, the composition ratio of the film formed on the substrate S can be adjusted by adjusting the ratio of the current supplied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the current supplied by the second power supply PS2 to the second electrode E2 via the second terminal TM2. That is, the ratio of the current supplied to the first electrode E1 and the current supplied to the second electrode E2 should be determined according to the composition ratio of the film to be formed on the substrate S.

[0056] In one example, aluminum is used as the first material, scandium as the second material, nitrogen gas is supplied to a vacuum chamber CH, and an aluminum scandium nitride film can be formed on a substrate S. The composition ratio of the aluminum scandium nitride film can be adjusted by adjusting the ratio of the voltage (or power or current) applied by the first power supply PS1 to the first electrode E1 via the first terminal TM1 and the voltage (or power or current) applied by the second power supply PS2 to the second electrode E2 via the second terminal TM2.

[0057] Figure 20 schematically shows the configuration of the plasma processing apparatus 1 of the third embodiment. The plasma processing apparatus 1 of the third embodiment is modified by changing the second float balun BL2 in the float balun BL of the plasma processing apparatus 1 of the first or second embodiment to a 9:1 type float balun. The third embodiment is n ２ This indicates that float baluns other than the 4:1 type float balun can be used as the Type 1 float balun. ２ The value of n in a Type 1 float balun can be any natural number greater than or equal to 2, but 2 or 3 is preferred.

[0058] Second float balance (n ２ Even when a 9:1 type float balun is used as BL2 (Type 1 float balun), the 1:1 type float baluns BL1 and n ２ The combined impedance of the float balun BL, which consists of a type 1 float balun BL2, is less than or equal to the combined impedance of a 1:1 type float balun, n ２ It is desirable that the combined impedance is greater than that of a Type 1 float balun.

[0059] In the plasma processing apparatus 1 of the third embodiment, the combined impedance of the 1:1 type float balun BL1 is X1 / 3, where X1 is the inductance of each coil constituting the 1:1 type float balun BL1. The combined impedance of the 9:1 type float balun BL2 is X2 / 9, where X2 is the inductance of each coil constituting the 9:1 type float balun BL2.

[0060] This disclosure can be applied, for example, to the deposition of aluminum nitride (AlN) films, or aluminum scandium nitride (AlScN) films, which are aluminum nitride (AlN) doped with scandium (Sc), as piezoelectric materials for MEMS (micro-electro-mechanical systems) devices, more specifically, for acoustic wave filters, microspeakers, and ultrasonic sensors. The reason for adding scandium to aluminum nitride is that it provides higher piezoelectric properties than aluminum nitride, and it is known that the higher the concentration of scandium, the higher the piezoelectric properties. Pulsed DC reactive sputtering is generally widely used as a method for forming these piezoelectric materials as thin films for MEMS.

[0061] (Example) Figure 22 illustrates the FWHM of an aluminum nitride (AlN) film formed by the sputtering apparatus shown in Figure 14. Here, an aluminum target was sputtered using argon and nitrogen. The AlN film was measured by X-ray diffraction (XRD), and after confirming that it was an AlN(002) oriented crystal structure film from the peak position of the diffraction pattern, the orientation of AlN(002) was measured by X-ray crystallography (XRC). The full width at half maximum (FWHM) was determined from the XRC analysis results. A smaller FWHM indicates a higher orientation of the film.

[0062] In the example, a 27.12 MHz high-frequency power supply was used as the first high-frequency power supply RF1, and DC power supplies were used as the first power supply PS1 and the second power supply PS2. The power of the first high-frequency power supply RF1 was set to 3000W, and the power of each of the first power supply PS1 and the second power supply PS2 was set to 1000W. On the other hand, in the comparative example, the first high-frequency power supply RF1 was not used, and pulse power supplies were used as the first power supply PS1 and the second power supply PS2, with each power set to 1500W. In addition, in the comparative example, the ON time of the pulse power supply was set to 80%. The substrate was a bare Si wafer with a diameter of 200 mm, and an AlN film was formed to a thickness of 1000 nm while heating the substrate. It is also possible to control the film stress by adjusting the output power of the second high-frequency power supply RF2.

[0063] In Figure 22, Radius = 0 mm represents the measurement result at the center of the substrate, and Radius = 80 mm represents the measurement result at a position 80 mm from the center of the substrate (i.e., near the outer edge of the substrate). The aluminum nitride film formed in the example showed a smaller FWHM than the aluminum nitride film formed in the comparative example. Furthermore, the aluminum nitride film formed in the comparative example showed a large difference in FWHM between the center and the outer edge of the substrate, indicating non-uniform orientation within the substrate plane. On the other hand, the aluminum nitride film formed in the example showed a small difference in FWHM between the center and the outer edge of the substrate, indicating uniform orientation within the substrate plane. This is because, when film deposition is performed using a pulsed DC power supply, there is a difference in the amount of plasma and radicals irradiated to the outer edge of the substrate, which is directly beneath the target, and to the center of the substrate, which is not covered by the target's projection plane. However, according to the example, the plasma is confined between the two targets, resulting in more uniform irradiation of the substrate with plasma and radicals. Therefore, an aluminum nitride film with uniform orientation from the center to the outer edge of the substrate is formed.

[0064] Figures 23 and 24 show the composition ratios of aluminum scandium nitride (AlScN) formed by the sputtering apparatus shown in Figure 14. Here, Figure 23 shows the composition ratio of aluminum scandium nitride formed in the center of the substrate, and Figure 24 shows the composition ratio of aluminum scandium nitride formed on the outer periphery of the substrate. Furthermore, the results shown in Figures 23 and 24 are the result of sputtering in a nitrogen gas atmosphere with an aluminum target attached to the first electrode E1 and a scandium target attached to the second electrode E2.

[0065] The output power of the first high-frequency power supply RF1 was kept constant at 3000W, the output power of the first power supply PS1 for adjusting the composition ratio was kept constant at 2000W, and the output power of the second power supply PS2 was set in the range of 0W to 2000W. By changing the output power of the second power supply PS2, aluminum scandium nitride films with a scandium (Sc) concentration of approximately 20% to 40% were obtained. The substrate used in this case was a bare Si wafer with a diameter of 200 mm, and an AlScN film was formed to a thickness of 1000 nm while heating the substrate. When the scandium concentration at the center of the substrate and the outer edge of the substrate (85 mm from the center of the substrate) was checked, the difference was extremely small, indicating that an aluminum scandium nitride film with a uniform composition ratio was obtained. The vertical axis "Sc Concentration" refers to the ratio of scandium to aluminum [Sc / (Sc+Al) ratio].

[0066] By using the film deposition method shown in this embodiment, it is possible to form aluminum scandium nitride films with excellent properties and adjustable composition ratios, for example, as piezoelectric materials used for MEMS (micro-electro-mechanical systems) devices.

[0067] Figure 25 schematically shows the configuration of the plasma processing apparatus 1 of the fourth embodiment. Matters not mentioned in the description of the fourth embodiment may be described in the descriptions of the first to third embodiments. The plasma processing apparatus 1 may include, for example, a high-frequency power supply RF, an impedance matching circuit MB, a float balun BL, a blocking capacitor BC1, a vacuum vessel CH, and a first electrode E1, a second electrode E2, and a third electrode E3. The first electrode E1, the second electrode E2, and the third electrode E3 are provided in the vacuum vessel CH and generate plasma in the internal space of the vacuum vessel CH by supplying high-frequency power to the internal space of the vacuum vessel CH. The third electrode E3 may function as an anode. The vacuum vessel CH may be grounded. The first electrode E1, the second electrode E2, and the third electrode E3 may be arranged in the internal space of the vacuum vessel CH, or they may define the internal space together with the vacuum vessel CH, as illustrated in Figure 25. The first electrode E1, the second electrode E2, and the third electrode E3 may be supported by the vacuum vessel CH via an insulator INS, for example. In the example shown in Figure 25, the target T is held by the first electrode E1 and the substrate S is held by the second electrode E2, and the plasma processing apparatus 1 is configured as a sputtering apparatus. However, the plasma processing apparatus 1 may also be configured as an etching apparatus for etching the substrate S.

[0068] Float balun BL is a 1:1 type float balun BL1 and n ２ : Includes a 1:1 type float balun (n is a natural number greater than or equal to 2). Current is supplied from the impedance matching circuit MB1 to the 1:1 type float balun BL1, and n ２ Current is supplied to the first electrode E1 and the second electrode E2 via the Type 1 float balun BL2. ２ The Type 1 float balun BL2 can be, for example, a 4:1 type float balun or a 9:1 type float balun.

[0069] The plasma processing apparatus 1 may include a first terminal TM1 electrically connected to a first electrode E1, a second terminal TM2 electrically connected to a second electrode E2, and a third terminal TM3 electrically connected to a third electrode E3. The negative output terminal NO1 of a first power supply PS1 may be electrically connected to the first terminal TM1, and the negative output terminal NO2 of a second power supply PS2 may be electrically connected to the second terminal TM2. The positive output terminal PO1 of the first power supply PS1 and the positive output terminal PO2 of the second power supply PS2 may be electrically connected to the third terminal TM3. The first power supply PS1 and the second power supply PS2 may be understood as external devices of the plasma processing apparatus 1 or as part of the plasma processing apparatus 1. The first power supply PS1 and the second power supply PS2 may be DC power supplies. The DC power supply may be a power supply that continuously outputs a set voltage, a pulsed DC power supply, a HiPIMS (High Power Impulse Magnetron Sputtering) power supply, or any other type of power supply.

[0070] The third electrode E3 may be positioned between the first electrode E1 and the second electrode E2. In other words, in an orthogonal projection onto a virtual plane including the surface on which the substrate S is placed, the third electrode E3 may be positioned between the first electrode E1 and the second electrode E2. The positive output terminal PO1 of the first power supply PS1 and the positive output terminal PO2 of the second power supply PS2 are not grounded.

[0071] The plasma processing apparatus 1 may have an additional electrode E4 provided in the vacuum chamber CH. The additional electrode E4 (fourth electrode) may be driven by a power source such as DC or AC. Driving the additional electrode E4 with a power source is advantageous for confining the plasma to a limited space. The plasma processing apparatus 1 may further include a second high-frequency power supply RF2 and a second impedance matching circuit MB2 for driving the additional electrode E4. The additional electrode E4 may constitute at least a part of the substrate holding section that holds the substrate S to be processed. The additional electrode E4 may be arranged to face the third electrode E3. Alternatively, the additional electrode E4 may be arranged to face the first electrode E1, the second electrode E2, and the third electrode E3. The plasma processing apparatus 1 may include a rotating mechanism RM for rotating the substrate holding section or the additional electrode E4.

[0072] Figure 26 schematically shows the configuration of the plasma processing apparatus 1 of the fifth embodiment. Matters not mentioned in the description of the fifth embodiment may be described in the descriptions of the first to fourth embodiments. In the plasma processing apparatus 1 of the fifth embodiment, the third electrode E3 is not positioned between the first electrode E1 and the second electrode E2. In another view, in the plasma processing apparatus 1 of the fifth embodiment, in the orthogonal projection onto a virtual plane including the surface on which the substrate S is placed, the third electrode E3 is not positioned between the first electrode E1 and the second electrode E2. In yet another view, in the plasma processing apparatus 1 of the fifth embodiment, the third electrode E3 may be positioned so as not to face either the additional electrode E4 or the substrate S.

[0073] The following describes a plasma processing method for forming a film on a substrate S using a plasma processing apparatus 1 according to the fourth or fifth embodiment. The plasma processing method may include a first step of attaching a first target T1 made of a first material to a first electrode E1 and a second target T2 made of a second material different from the first material to a second electrode E2. The plasma processing method may also include a second step of rotating the substrate S in a vacuum chamber CH. In the second step, the substrate S may be rotated, for example, by rotating an additional electrode E4 that functions as a substrate holder. The plasma processing method electrically connects the negative output terminal NO1 of a first power supply PS1 to a first terminal TM1, the negative output terminal NO2 of a second power supply PS2 to a second terminal TM2, the positive output terminal PO1 of a first power supply PS1 and the positive output terminal PO2 of a second power supply PS2 to a third terminal TM3, and connects a 1:1 type float balun BL1 and n from an impedance matching circuit MB1. ２ The plasma processing method may also include a third step of generating plasma in a vacuum chamber CH by supplying current to a first electrode E1 and a second electrode E2 via a type 1 float balun BL2. The plasma processing method may also include a fourth step of forming a film on a substrate S using sputtered particles from a first target T1 and a second target T2 and ions.

[0074] The technical ideas derived from this disclosure are not limited to the exemplary embodiments disclosed, but are intended to encompass various modifications of the exemplary embodiments, or substitutions with equivalent structures or functions. The scope of the following claims should be interpreted in the broadest way to encompass all such modifications and equivalent structures and functions.

Claims

1. An impedance matching circuit, a vacuum vessel, a first electrode, a second electrode, and a third electrode provided in the vacuum vessel, a 1:1 type float balun, and n ２ The 1:1 type float balun comprises: a 1:1 type float balun (where n is a natural number of 2 or more); a first terminal electrically connected to the first electrode; a second terminal electrically connected to the second electrode; and a third terminal electrically connected to the third electrode, wherein the negative output terminal of the first power supply is electrically connected to the first terminal, the negative output terminal of the second power supply is electrically connected to the second terminal, and the positive output terminals of the first and second power supplies are electrically connected to the third terminal; current is supplied from the impedance matching circuit to the 1:1 type float balun, and current is supplied from the 1:1 type float balun to the n ２ A plasma processing apparatus characterized in that current is supplied to the first electrode and the second electrode via a Type 1 float balun.

2. The plasma processing apparatus according to claim 1, characterized in that the third electrode is disposed between the first electrode and the second electrode.

3. The plasma processing apparatus according to claim 1 or 2, characterized in that the positive output terminal of the first power supply and the positive output terminal of the second power supply are not grounded.

4. The plasma processing apparatus according to any one of claims 1 to 3, characterized in that the first power supply and the second power supply include a DC power supply.

5. The plasma processing apparatus according to claim 4, further comprising a fourth electrode provided in the vacuum vessel, wherein the fourth electrode is driven by a power supply.

6. The plasma processing apparatus according to claim 5, characterized in that the fourth electrode constitutes at least a part of the substrate holding portion that holds the substrate to be processed.

7. The plasma processing apparatus according to claim 6, characterized in that the fourth electrode is arranged to face the third electrode.

8. The plasma processing apparatus according to claim 6, characterized in that the fourth electrode is arranged to face the first electrode, the second electrode, and the third electrode.

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