Plasma processing apparatus

Abstract

A plasma processing apparatus includes: a balun having a first unbalanced terminal, a second unbalanced terminal, a first balanced terminal, and a second balanced terminal; a vacuum chamber grounded; a first electrode electrically connected to the first balanced terminal; a second electrode electrically connected to the second balanced terminal; an impedance matching circuit; a first power supply connected to the balun via the impedance matching circuit and configured to supply high frequency to the first electrode via the impedance matching circuit and the balun; a low-pass filter; and a second power supply configured to supply a voltage to the first electrode via the low-pass filter.

Description

[0001] This application is a divisional application of a Chinese patent application with the application number 201780092519.9, the filing date of June 27, 2017, and the title "Plasma Processing Apparatus". Technical Field

[0002] The present invention relates to a plasma processing apparatus. Background Art

[0003] There is provided a plasma processing apparatus that generates plasma by applying high frequency between two electrodes and processes a substrate by the plasma. Such a plasma processing apparatus can operate as an etching apparatus or a sputtering apparatus based on the area ratio and / or bias voltage of the two electrodes. The plasma processing apparatus configured as a sputtering apparatus includes a first electrode that holds a target and a second electrode that holds a substrate. High frequency is applied between the first electrode and the second electrode (between the target and the substrate), and plasma is generated between the target and the anode. When the plasma is generated, a self-bias voltage is generated on the surface of the target. This causes ions to collide with the target, and particles of the material constituting the target are released from the target.

[0004] Patent Document 1 describes a plasma processing apparatus that includes a grounded chamber, a target electrode connected to an RF source via an impedance matching circuit system, and a substrate holding electrode grounded via a substrate electrode tuning circuit.

[0005] In the sputtering apparatus described in Patent Document 1, in addition to the substrate holding electrode, the chamber also serves as an anode. The self-bias voltage can depend on the state of the part that can serve as the cathode and the state of the part that can serve as the anode. Therefore, if the chamber also serves as an anode in addition to the substrate holding electrode part, the self-bias voltage can vary depending on the state of the part of the chamber that serves as the anode. The change in the self-bias voltage changes the plasma potential, and the change in the plasma potential can affect the characteristics of the film to be formed.

[0006] If a film is formed on a substrate using a sputtering apparatus, a film is also formed on the inner surface of the chamber. This can change the state of the part of the chamber that can serve as the anode. Therefore, if the sputtering apparatus is continuously used, the self-bias voltage varies depending on the film formed on the inner surface of the chamber, and the plasma potential also changes. Therefore, if the sputtering apparatus is used for a long time, it has been difficult to maintain the characteristics of the film formed on the substrate constant.

[0007] Similarly, if an etching apparatus is used for a long time, the self-bias voltage varies depending on the film formed on the inner surface of the chamber, and this changes the plasma potential. Therefore, it is difficult to maintain the etching characteristics of the substrate constant.

[0008] In the sputtering apparatus described in Patent Document 1, the high-frequency power needs to be adjusted to control the self-bias voltage. However, if the high-frequency power is changed to adjust the self-bias voltage, the plasma density also changes. Therefore, in the past, it has been impossible to adjust the self-bias voltage and the plasma density independently. Similarly, in the past, the etching apparatus has been unable to adjust the self-bias voltage and the plasma density independently.

[0009] Prior Art Documents

[0010] Patent Documents

[0011] Patent Document 1: Japanese Patent Laid-Open No. 55-35465 Summary of the Invention

[0012] Problems to be Solved by the Invention

[0013] The present invention has been made based on the recognition of the above problems, and an object thereof is to provide a technique that is advantageous for stabilizing the plasma potential and for independently adjusting the voltage applied to the electrode and the plasma density.

[0014] According to one aspect of the present invention, there is provided a plasma processing apparatus including: a balun including a first unbalanced terminal, a second unbalanced terminal, a first balanced terminal, and a second balanced terminal; a grounded vacuum chamber; a first electrode electrically connected to the first balanced terminal; a second electrode electrically connected to the second balanced terminal; an impedance matching circuit; a first power supply connected to the balun via the impedance matching circuit and configured to supply high frequency to the first electrode via the impedance matching circuit and the balun; a low-pass filter; and a second power supply that supplies a voltage to the first electrode via the low-pass filter.

[0015] According to the present invention, there is provided a technique that is advantageous for stabilizing the plasma potential and for independently adjusting the voltage applied to the electrode and the plasma density. Brief Description of the Drawings

[0016] Figure 1 is a circuit diagram schematically showing the arrangement of the plasma processing apparatus according to the first embodiment of the present invention.

[0017] Figure 2A is a circuit diagram showing an example of the arrangement of the balun.

[0018] Figure 2B is a circuit diagram showing another example of the arrangement of the balun.

[0019] Figure 3 is a circuit diagram for explaining the function of the balun 103.

[0020] Figure 4It is a table illustrating the relationship among the exemplary currents I1 (= I2), I2', and I3, ISO, and α (= X / Rp).

[0021] Figure 5A It is a time chart showing the results of simulating the plasma potential and the cathode potential when 1.5 ≤ X / Rp ≤ 5000 is satisfied.

[0022] Figure 5B It is a time chart showing the results of simulating the plasma potential and the cathode potential when 1.5 ≤ X / Rp ≤ 5000 is satisfied.

[0023] Figure 5C It is a time chart showing the results of simulating the plasma potential and the cathode potential when 1.5 ≤ X / Rp ≤ 5000 is satisfied.

[0024] Figure 5D It is a time chart showing the results of simulating the plasma potential and the cathode potential when 1.5 ≤ X / Rp ≤ 5000 is satisfied.

[0025] Figure 6A It is a time chart showing the results of simulating the plasma potential and the cathode potential when 1.5 ≤ X / Rp ≤ 5000 is not satisfied.

[0026] Figure 6B It is a time chart showing the results of simulating the plasma potential and the cathode potential when 1.5 ≤ X / Rp ≤ 5000 is not satisfied.

[0027] Figure 6C It is a time chart showing the results of simulating the plasma potential and the cathode potential when 1.5 ≤ X / Rp ≤ 5000 is not satisfied.

[0028] Figure 6D It is a time chart showing the results of simulating the plasma potential and the cathode potential when 1.5 ≤ X / Rp ≤ 5000 is not satisfied.

[0029] Figure 7 It is a circuit diagram illustrating a method for confirming Rp - jXp.

[0030] Figure 8 It is a circuit diagram schematically showing the arrangement of a plasma processing apparatus according to a second embodiment of the present invention.

[0031] Figure 9 It is a circuit diagram schematically showing the arrangement of a plasma processing apparatus according to a third embodiment of the present invention.

[0032] Figure 10 It is a circuit diagram schematically showing the arrangement of a plasma processing apparatus according to a fourth embodiment of the present invention.

[0033] Figure 11 is a circuit diagram schematically showing the arrangement of a plasma processing apparatus according to a fifth embodiment of the present invention.

[0034] Figure 12 is a circuit diagram schematically showing the arrangement of a plasma processing apparatus according to a sixth embodiment of the present invention. Detailed Description

[0035] The present invention will be described below with reference to the accompanying drawings by way of exemplary embodiments.

[0036] Figure 1 schematically shows the arrangement of a plasma processing apparatus 1 according to a first embodiment of the present invention. The plasma processing apparatus 1 includes: a balun (balanced / unbalanced conversion circuit) 103, a vacuum chamber 110, a first electrode 106, a second electrode 111, a low-pass filter 115, and a power supply 116 (second power supply). Alternatively, it is understandable that the plasma processing apparatus 1 includes a balun 103 and a main body 10, and the main body 10 includes a vacuum chamber 110, a first electrode 106, a second electrode 111, a low-pass filter 115, and a power supply 116 (second power supply). The main body 10 includes a first terminal 251 and a second terminal 252. The power supply 116 may be, for example, a DC power supply or an AC power supply. The DC power supply can generate a DC voltage containing an AC component. The main body 10 may include a third terminal 253 connected to the vacuum chamber 110. The plasma processing apparatus 1 may further include an impedance matching circuit 102 and a high-frequency power supply 101 (first power supply).

[0037] The balun 103 includes a first unbalanced terminal 201, a second unbalanced terminal 202, a first balanced terminal 211, and a second balanced terminal 212. An unbalanced circuit is connected to the first unbalanced terminal 201 and the second unbalanced terminal 202 of the balun 103, and a balanced circuit is connected to the first balanced terminal 211 and the second balanced terminal 212 of the balun 103. The vacuum chamber 110 is formed of a conductor and is grounded. The balun 103 may further include a midpoint terminal 213. The balun 103 may be configured such that the voltage of the midpoint terminal 213 is set to the midpoint between the voltage of the first balanced terminal 211 and the voltage of the second balanced terminal 212. The midpoint terminal 213 may be electrically connected to the third terminal 253 of the main body 10.

[0038] In the first embodiment, the first electrode 106 serves as a cathode and holds the target 109. The target 109 can be, for example, an insulator material or a conductor material. Further, in the first embodiment, the second electrode 111 serves as an anode and holds the substrate 112. The plasma processing apparatus 1 according to the first embodiment can operate as a sputtering apparatus that forms a film on the substrate 112 by sputtering the target 109. The first electrode 106 is electrically connected to the first balance terminal 211, and the second electrode 111 is electrically connected to the second balance terminal 212. When the first electrode 106 and the first balance terminal 211 are electrically connected to each other, this indicates that a current path is formed between the first electrode 106 and the first balance terminal 211, such that current flows between the first electrode 106 and the first balance terminal 211. Similarly, in this specification, when a and b are electrically connected, this indicates that a current path is formed between a and b, such that current flows between a and b.

[0039] The above arrangement can also be understood as an arrangement in which the first electrode 106 is electrically connected to the first terminal 251, the second electrode 111 is electrically connected to the second terminal 252, the first terminal 251 is electrically connected to the first balance terminal 211, and the second terminal 252 is electrically connected to the second balance terminal 212.

[0040] In the first embodiment, the first electrode 106 and the first balance terminal 211 (first terminal 251) are electrically connected via a blocking capacitor 104. The blocking capacitor 104 blocks direct current between the first balance terminal 211 and the first electrode 106 (or between the first balance terminal 211 and the second balance terminal 212). Instead of providing the blocking capacitor 104, the impedance matching circuit 102 (to be described later) can be configured to block direct current flowing between the first unbalanced terminal 201 and the second unbalanced terminal 202. The first electrode 106 can be supported by the vacuum vessel 110 via an insulator 107. The second electrode 111 can be supported by the vacuum vessel 110 via an insulator 108. Alternatively, an insulator 108 can be arranged between the second electrode 111 and the vacuum vessel 110.

[0041] The high-frequency power supply 101 (first power supply) supplies high frequency (high-frequency current, high-frequency voltage, and high-frequency power) between the first unbalanced terminal 201 and the second unbalanced terminal 202 of the balun 103 via the impedance matching circuit 102. In other words, the high-frequency power supply 101 supplies high frequency (high-frequency current, high-frequency voltage, and high-frequency power) between the first electrode 106 and the second electrode 111 via the impedance matching circuit 102, the balun 103, and the blocking capacitor 104. Alternatively, it can also be understood that the high-frequency power supply 101 supplies high frequency between the first terminal 251 and the second terminal 252 of the main body 10 via the impedance matching circuit 102 and the balun 103.

[0042] The power supply 116 (second power supply) may be configured to supply a negative DC voltage (bias voltage) or an AC voltage to the first electrode 106 via the low-pass filter 115. The low-pass filter 115 blocks the high frequency supplied from the balun 103 so that it is not transmitted to the power supply 116. By supplying a negative DC voltage or an AC voltage from the power supply 116 to the first electrode 106, the voltage on the surface of the target 109 or the ion energy colliding with the surface of the target 109 can be controlled (determined). When the target 109 is made of a conductive material, the voltage on the surface of the target 109 can be controlled by supplying a negative DC voltage from the power supply 116 to the first electrode 106. When the target 109 is made of an insulating material, the ion energy colliding with the surface of the target 109 can be controlled by supplying an AC voltage from the power supply 116 to the first electrode 106.

[0043] If the target 109 is made of an insulating material and the power supply 116 (second power supply) supplies an AC voltage to the first electrode 106, the frequency of the voltage supplied from the power supply 116 to the first electrode 106 can be set lower than the frequency of the high frequency generated by the high-frequency power supply 101 (first power supply). In this case, the frequency of the voltage supplied from the power supply 116 to the first electrode 106 is preferably set in the range of several hundred KHz to several MHz.

[0044] A gas (e.g., Ar, Kr, or Xe gas) is supplied into the internal space of the vacuum chamber 110 through a gas supply section (not shown) provided in the vacuum chamber 110. Further, the high-frequency power supply 101 (first power supply) supplies high frequency between the first electrode 106 and the second electrode 111 via the impedance matching circuit 102, the balun 103, and the blocking capacitor 104. Further, the DC power supply 116 supplies a negative DC voltage or an AC voltage to the first electrode 106 via the low-pass filter 115. This generates plasma between the first electrode 106 and the second electrode 111, and the surface of the target 109 is controlled to a negative voltage, or the ion energy colliding with the surface of the target 109 is controlled. Then, the ions in the plasma collide with the surface of the target 109, and particles of the material constituting the target 109 are emitted from the target 109. The particles form a film on the substrate 112.

[0045] Figure 2A An example of the arrangement of the balun 103 is shown. Figure 2A The shown balun 103 includes a first coil 221 connecting the first unbalanced terminal 201 and the first balanced terminal 211 and a second coil 222 connecting the second unbalanced terminal 202 and the second balanced terminal 212. The first coil 221 and the second coil 222 are coils having the same number of turns and share a core.

[0046] Figure 2B Another example of the arrangement of the balun 103 is shown.Figure 2B The balun 103 shown includes a first coil 221 connecting a first unbalanced terminal 201 and a first balanced terminal 211, and a second coil 222 connecting a second unbalanced terminal 202 and a second balanced terminal 212. The first coil 221 and the second coil 222 are coils having the same number of turns and share a core. Figure 2B The balun 103 shown further includes a third coil 223 and a fourth coil 224 both connected between the first balanced terminal 211 and the second balanced terminal 212. The third coil 223 and the fourth coil 224 are configured such that the connection node of the third coil 223 and the fourth coil 224 is set to the midpoint between the voltage of the first balanced terminal 211 and the voltage of the second balanced terminal 212. This connection node is connected to a midpoint terminal 213. The third coil 223 and the fourth coil 224 are coils having the same number of turns and share a core. The midpoint terminal 213 can be grounded, can be connected to the vacuum vessel 110, or can be floating.

[0047] Refer to Figure 3 Describe the function of the balun 103. Let the current flowing through the first unbalanced terminal 201 be I1, the current flowing through the first balanced terminal 2 * 11 be I2, the current flowing through the second unbalanced terminal 202 be I2', and the current flowing to the ground in the current I2 be I3. When I3 = 0, that is, when no current flows to the ground on the balanced circuit side, the isolation performance of the balanced circuit with respect to the ground is the highest. When I3 = I2, that is, when all the current I2 flowing through the first balanced terminal 211 flows to the ground, the isolation performance of the balanced circuit with respect to the ground is the lowest. The index ISO representing the degree of isolation performance is given by:

[0048] ISO[dB] = 20log(I3 / I2')

[0049] Under this definition, the higher the absolute value of the index ISO, the higher the isolation performance.

[0050] In Figure 3 , Rp - jXp represents the impedance (including the reactance of the blocking capacitor 104) when looking at the side of the first electrode 106 and the second electrode 111 (the side of the main body 10) from the side of the first balanced terminal 211 and the second balanced terminal 212 in the state where plasma is generated in the internal space of the vacuum vessel 110. Note that this impedance is the impedance at the frequency of the high frequency generated by the high frequency power supply 101, and the impedances of the low - pass filter 115 and the DC power supply 116 are negligible. Rp represents the resistance component, and - Xp represents the reactance component. In addition, in Figure 3 , X represents the reactance component (inductive component) of the impedance of the first coil 221 of the balun 103. ISO has a correlation with X / Rp.

[0051] To clarify the advantages of the arrangement in which the high-frequency power supply 101 supplies high-frequency power between the first electrode 106 and the second electrode 111 via the balun 103, the operation of the plasma processing apparatus 1 in a state where the power supply 116 (and the low-pass filter 115) is removed from the plasma processing apparatus 1 (main body 10) will be described. Figure 4 The relationship between the currents I1 (= I2), I2', I3, ISO, and α (= X / Rp) in a state where the power supply 116 (and the low-pass filter 115) is removed from the plasma processing apparatus 1 (main body 10) is illustrated.

[0052] The present inventors have found that when 1.5 ≤ X / Rp ≤ 5000 is satisfied, the potential of the plasma (plasma potential) formed in the internal space of the vacuum vessel 110 (the space between the first electrode 106 and the second electrode 111) is insensitive to the state of the inner surface of the vacuum vessel 110. When the plasma potential is insensitive to the state of the inner surface of the vacuum vessel 110, this indicates that the plasma potential can be stabilized even when the plasma processing apparatus 1 is used for a long time. 1.5 ≤ X / Rp ≤ 5000 corresponds to -10.0 dB ≥ ISO ≥ -80 dB.

[0053] Figures 5A to 5D The results of simulating the plasma potential and the potential of the first electrode 106 (cathode potential) when 1.5 ≤ X / Rp ≤ 5000 is satisfied are each shown. Figure 5A The plasma potential and the cathode potential in a state where no film is formed on the inner surface of the vacuum vessel 110 are shown. Figure 5B The plasma potential and the cathode potential in a state where a resistive film (1000 Ω) is formed on the inner surface of the vacuum vessel 110 are shown. Figure 5C The plasma potential and the cathode potential in a state where an inductive film (0.6 μH) is formed on the inner surface of the vacuum vessel 110 are shown. Figure 5D The plasma potential and the cathode potential in a state where a capacitive film (0.1 nF) is formed on the inner surface of the vacuum vessel 110 are shown. Refer to Figures 5A to 5D It can be understood that when 1.5 ≤ X / Rp ≤ 5000 is satisfied, the plasma potential is stable in various states of the inner surface of the vacuum vessel 110.

[0054] Figures 6A to 6D The results of simulating the plasma potential and the potential of the first electrode 106 (cathode potential) when 1.5 ≤ X / Rp ≤ 5000 is not satisfied are each shown. Figure 6A The plasma potential and the cathode potential in a state where no film is formed on the inner surface of the vacuum vessel 110 are shown. Figure 6BShows the plasma potential and the cathode potential in a state where a resistive film (1000 Ω) is formed on the inner surface of the vacuum vessel 110. Figure 6C Shows the plasma potential and the cathode potential in a state where an inductive film (0.6 μH) is formed on the inner surface of the vacuum vessel 110. Figure 6D Shows the plasma potential and the cathode potential in a state where a capacitive film (0.1 nF) is formed on the inner surface of the vacuum vessel 110. Refer to Figures 6A to 6D It can be understood that when 1.5 ≤ X / Rp ≤ 5000 is not satisfied, the plasma potential varies depending on the state of the inner surface of the vacuum vessel 110.

[0055] In the case where X / Rp > 5000 (for example, X / Rp = ∞) and the case where X / Rp < 1.5 (for example, X / Rp = 1.0 or X / Rp = 0.5), the plasma potential is liable to vary depending on the state of the inner surface of the vacuum vessel 110. If X / Rp > 5000, then in a state where no film is formed on the inner surface of the vacuum vessel 110, discharge occurs only between the first electrode 106 and the second electrode 111. However, if X / Rp > 5000, then when a film starts to be formed on the inner surface of the vacuum vessel 110, the plasma potential responds sensitively thereto, and the results as Figures 6A to 6D illustrated are obtained. On the other hand, when X / Rp < 1.5, the current flowing to the ground via the vacuum vessel 110 is large. Therefore, the influence of the state of the inner surface of the vacuum vessel 110 (the electrical characteristics of the film formed on the inner surface) is significant, and the plasma potential varies depending on the film formation. Therefore, as described above, the plasma processing apparatus 1 should be configured to satisfy 1.5 ≤ X / Rp ≤ 5000.

[0056] Refer to Figure 7 A method for determining Rp - jXp (what is actually desired to know is only Rp) will be illustrated. Remove the balun 103 from the plasma processing apparatus 1, and connect the output terminal 230 of the impedance matching circuit 102 to the first terminal 251 (blocking capacitor 104) of the main body 10. Further, ground the second terminal 252 (second electrode 111) of the main body 10. In this state, the high-frequency power supply 101 supplies high-frequency to the first terminal 251 of the main body 10 via the impedance matching circuit 102. In Figure 7In the illustrated example, the impedance matching circuit 102 is equivalently formed by coils L1 and L2 and variable capacitors VC1 and VC2. Plasma generation can be achieved by adjusting the capacitance values of the variable capacitors VC1 and VC2. In a state where the plasma is stable, the impedance of the impedance matching circuit 102 matches the impedance Rp - jXp on the side of the main body 10 (the side of the first electrode 106 and the second electrode 111) during plasma generation. The impedance of the impedance matching circuit 102 at this time is given by Rp + jXp. Therefore, Rp - jXp (what is actually desired to know is only Rp) can be obtained based on the impedance Rp + jXp of the impedance matching circuit 102 during impedance matching. Alternatively, for example, Rp - jXp can be obtained through simulation based on design data.

[0057] Based on Rp obtained in this manner, the reactance component (inductive component) X of the impedance of the first coil 221 of the balun 103 is determined so as to satisfy 1.5 ≤ X / Rp ≤ 5000. By determining the reactance component of the balun 103 as described above, the plasma potential (and the self - bias voltage (the surface voltage of the target 109)) can be stabilized even without providing the power supply 116.

[0058] In addition, in an arrangement where the power supply 116 supplies a negative DC voltage to the first electrode 106 via the low - pass filter 115, the surface voltage of the target 109 can be controlled by this DC voltage. On the other hand, in an arrangement where the power supply 116 supplies an AC voltage to the first electrode 106 via the low - pass filter 115, the ion energy colliding with the surface of the target 109 can be controlled by this AC voltage. Therefore, the high - frequency power supplied between the first electrode 106 and the second electrode 111 from the high - frequency power supply 101 can be adjusted independently of the surface voltage of the target 109. In addition, in an arrangement where the power supply 116 supplies a negative DC voltage or an AC voltage to the first electrode 106 via the low - pass filter 115, the plasma potential can be made insensitive to the state of the inner surface of the vacuum vessel 110. Therefore, it is not always necessary to satisfy 1.5 ≤ X / Rp ≤ 5000. Even if 1.5 ≤ X / Rp ≤ 5000 is not satisfied, practical performance can be provided.

[0059] The relationship between the size of the first electrode 106 and the size of the second electrode 111 is not limited. However, the first electrode 106 and the second electrode 111 preferably have similar sizes. In this case, the self - bias voltage can be made low, and the surface voltage of the target 109 or the ion energy colliding with the surface of the target 109 can be freely controlled by the power supply 116.

[0060] Figure 8Schematically shows the arrangement of the plasma processing apparatus 1 according to the second embodiment of the present invention. The plasma processing apparatus 1 according to the second embodiment can operate as an etching apparatus for etching the substrate 112. In the second embodiment, the first electrode 106 serves as a cathode and holds the substrate 112. In the second embodiment, the second electrode 111 serves as an anode. In the plasma processing apparatus 1 according to the second embodiment, the first electrode 106 is electrically connected to the first balance terminal 211 via the blocking capacitor 104. In other words, in the plasma processing apparatus 1 according to the second embodiment, the blocking capacitor 104 is arranged in the electrical connection path between the first electrode 106 and the first balance terminal 211.

[0061] Figure 9 Schematically shows the arrangement of the plasma processing apparatus 1 according to the third embodiment of the present invention. The plasma processing apparatus 1 according to the third embodiment is a modification of the plasma processing apparatus 1 according to the first embodiment, and further includes at least one of a mechanism for vertically moving the second electrode 111 and a mechanism for rotating the second electrode 111. In Figure 9 the example shown, the plasma processing apparatus 1 includes a drive mechanism 114, and the drive mechanism 114 has both a mechanism for vertically moving the second electrode 111 and a mechanism for rotating the second electrode 111. A bellows 113 forming a vacuum partition can be provided between the vacuum vessel 110 and the drive mechanism 114. Similarly, the plasma processing apparatus 1 according to the second embodiment may also include at least one of a mechanism for vertically moving the second electrode 111 and a mechanism for rotating the second electrode 111.

[0062] In the third embodiment, the relationship between the size of the first electrode 106 and the size of the second electrode 111 is also not limited. However, the first electrode 106 and the second electrode 111 preferably have similar sizes.

[0063] Figure 10Schematically shows the arrangement of the plasma processing apparatus 1 according to the fourth embodiment of the present invention. Matters not mentioned regarding the plasma processing apparatus 1 according to the fourth embodiment may be in accordance with the first to third embodiments. The plasma processing apparatus 1 includes a balun 103, a vacuum chamber 110, a first electrode 106, a second electrode 135, a third electrode 151, low-pass filters 115 and 303, a power supply 116, and a DC power supply 304. Alternatively, it is understood that the plasma processing apparatus 1 includes a balun 103 and a main body 10, and the main body 10 includes a vacuum chamber 110, a first electrode 106, a second electrode 135, a third electrode 151, low-pass filters 115 and 303, a power supply 116, and a DC power supply 304. The main body 10 includes a first terminal 251 and a second terminal 252. The plasma processing apparatus 1 may further include impedance matching circuits 102 and 302, and high-frequency power supplies 101 and 301. The power supply 116 may be, for example, a DC power supply or an AC power supply. The DC power supply may generate a DC voltage with an AC component.

[0064] The balun 103 includes a first unbalanced terminal 201, a second unbalanced terminal 202, a first balanced terminal 211, and a second balanced terminal 212. An unbalanced circuit is connected to the first unbalanced terminal 201 and the second unbalanced terminal 202 of the balun 103, and a balanced circuit is connected to the first balanced terminal 211 and the second balanced terminal 212 of the balun 103. The balun 103 may further include a midpoint terminal as described above. The midpoint terminal may be electrically connected to the vacuum chamber 110.

[0065] The first electrode 106 holds a target 109. The target 109 may be, for example, an insulator material or a conductor material. The second electrode 135 is disposed around the first electrode 106. The first electrode 106 is electrically connected to the first balanced terminal 211 of the balun 103, and the second electrode 135 is electrically connected to the second balanced terminal 212 of the balun 103. The third electrode 151 holds a substrate 112. High-frequency may be supplied to the third electrode 151 from the high-frequency power supply 301 via the impedance matching circuit 302.

[0066] The above arrangement is understood as an arrangement in which the first electrode 106 is electrically connected to the first terminal 251, the second electrode 135 is electrically connected to the second terminal 252, the first terminal 251 is electrically connected to the first balanced terminal 211 of the balun 103, and the second terminal 252 is electrically connected to the second balanced terminal 212 of the balun 103.

[0067] The first electrode 106 and the first balance terminal 211 (first terminal 251) can be electrically connected via a blocking capacitor 104. The blocking capacitor 104 blocks direct current or alternating current from the power supply 116 between the first balance terminal 211 of the balun 103 and the first electrode 106 (or between the first balance terminal 211 and the second balance terminal 212 of the balun 103). Instead of providing the blocking capacitor 104, the impedance matching circuit 102 can be configured to block direct current or alternating current from the power supply 116 flowing between the first unbalanced terminal 201 and the second unbalanced terminal 202. Alternatively, the blocking capacitor 104 can be arranged between the second electrode 135 and the second balance terminal 212 (second terminal 252). The first electrode 106 and the second electrode 135 are supported by the vacuum chamber 110 via the insulator 132.

[0068] The high-frequency power supply 101 supplies high-frequency between the first unbalanced terminal 201 and the second unbalanced terminal 202 of the balun 103 via the impedance matching circuit 102. In other words, the high-frequency power supply 101 supplies high-frequency between the first electrode 106 and the second electrode 135 via the first impedance matching circuit 102, the balun 103, and the blocking capacitor 104. Alternatively, the high-frequency power supply 101 supplies high-frequency between the first terminal 251 and the second terminal 252 of the main body 10 via the impedance matching circuit 102 and the balun 103. The high-frequency power supply 301 supplies high-frequency to the third electrode 151 via the impedance matching circuit 302.

[0069] The power supply 116 supplies a negative direct current voltage (bias voltage) or an alternating current voltage to the first electrode 106 via the low-pass filter 115. The low-pass filter 115 blocks the high-frequency supplied from the balun 103 so that it is not transmitted to the power supply 116. By supplying a negative direct current voltage from the power supply 116 to the first electrode 106, the voltage on the surface of the target 109 can be controlled. By supplying an alternating current voltage from the power supply 116 to the first electrode 106, the ion energy colliding with the surface of the target 109 can be controlled. The DC power supply 304 supplies a direct current voltage (bias voltage) to the third electrode 151 via the low-pass filter 303. The low-pass filter 303 blocks the high-frequency supplied from the high-frequency power supply 301 so that it is not transmitted to the DC power supply 304. When the DC power supply 304 supplies a direct current voltage to the third electrode 151, the surface potential of the substrate 112 can be controlled.

[0070] In the fourth embodiment, the voltage on the surface of the target 109 or the ion energy colliding with the target 109 can also be controlled by supplying a negative direct current voltage or an alternating current voltage from the power supply 116 to the first electrode 106, so that the plasma density can be controlled by the high-frequency power supply 101 and the high-frequency power supply 301. In addition, in the fourth embodiment, it is also beneficial to make the plasma potential more stable that 1.5 ≤ X / Rp ≤ 5000.

[0071] In the fourth embodiment, the relationship between the size of the first electrode 106 and the size of the second electrode 135 is also not limited. However, the first electrode 106 and the second electrode 135 preferably have similar sizes.

[0072] Figure 11 The arrangement of the plasma processing apparatus 1 according to the fifth embodiment of the present invention is schematically shown. The plasma processing apparatus 1 according to the fifth embodiment has an arrangement obtained by adding a drive mechanism 114 to the plasma processing apparatus 1 according to the fourth embodiment. The drive mechanism 114 may include at least one of a mechanism for vertically moving the third electrode 151 and a mechanism for rotating the third electrode 151.

[0073] In the fifth embodiment, the relationship between the size of the first electrode 106 and the size of the second electrode 135 is also not limited. However, the first electrode 106 and the second electrode 135 preferably have similar sizes.

[0074] Figure 12 The arrangement of the plasma processing apparatus 1 according to the sixth embodiment of the present invention is schematically shown. Matters not mentioned regarding the sixth embodiment may be in accordance with the first to fifth embodiments. The plasma processing apparatus 1 according to the sixth embodiment includes a plurality of first high-frequency supply units and at least one second high-frequency supply unit. An example in which the plurality of first high-frequency supply units are formed of two high-frequency supply units will be described. Additionally, subscripts a and b are used to distinguish the two high-frequency supply units and their associated components from each other. Similarly, subscripts a and b are used to distinguish the two targets from each other.

[0075] One of the plurality of first high-frequency supply units may include a first electrode 106a, a second electrode 135a, a balun 103a, a power supply 116a, a low-pass filter 115a, a high-frequency power supply 101a, an impedance matching circuit 102a, and a blocking capacitor 104a. The other of the plurality of first high-frequency supply units may include a first electrode 106b, a second electrode 135b, a balun 103b, a power supply 116b, a low-pass filter 115b, a high-frequency power supply 101b, an impedance matching circuit 102b, and a blocking capacitor 104b. The second high-frequency supply unit may include a high-frequency power supply 301, an impedance matching circuit 302, a DC power supply 304, and a low-pass filter 303. Each of the power supplies 116a and 116b may be, for example, a DC power supply or an AC power supply. The DC power supply may generate a DC voltage containing an AC component.

[0076] From another perspective, the plasma processing apparatus 1 may include: baluns 103a, 103b, a vacuum chamber 110, first electrodes 106a, 106b, second electrodes 135a, 135b, a third electrode 151, low-pass filters 115a, 115b, 303, power supplies 116a, 116b, a DC power supply 304, and high-frequency power supplies 101a, 101b, 301.

[0077] The balun 103a includes a first unbalanced terminal 201a, a second unbalanced terminal 202a, a first balanced terminal 211a, and a second balanced terminal 212a. An unbalanced circuit is connected to the first unbalanced terminal 201a and the second unbalanced terminal 202a of the balun 103a, and a balanced circuit is connected to the first balanced terminal 211a and the second balanced terminal 212a of the balun 103a. The balun 103b includes a first unbalanced terminal 201b, a second unbalanced terminal 202b, a first balanced terminal 211b, and a second balanced terminal 212b. An unbalanced circuit is connected to the first unbalanced terminal 201b and the second unbalanced terminal 202b of the balun 103b, and a balanced circuit is connected to the first balanced terminal 211b and the second balanced terminal 212b of the first balun 103b.

[0078] The first electrodes 106a, 106b hold targets 109a, 109b, respectively. Each of the targets 109a, 109b may be, for example, an insulator material or a conductor material. The second electrodes 135a, 135b are respectively disposed around the first electrodes 106a, 106b. The first electrodes 106a, 106b are respectively electrically connected to the first balanced terminals 211a, 211b of the baluns 103a, 103b, and the second electrodes 135a, 135b are respectively electrically connected to the second balanced terminals 212a, 212b of the baluns 103a, 103b. The high-frequency power supply 101a supplies high-frequency (high-frequency current, high-frequency voltage, and high-frequency power) between the first unbalanced terminal 201a and the second unbalanced terminal 202a of the balun 103a via an impedance matching circuit 102a. The high-frequency power supply 101b supplies high-frequency (high-frequency current, high-frequency voltage, and high-frequency power) between the first unbalanced terminal 201b and the second unbalanced terminal 202b of the balun 103b via an impedance matching circuit 102b. The third electrode 151 holds a substrate 112. High-frequency can be supplied to the third electrode 151 from the high-frequency power supply 301 via an impedance matching circuit 302.

[0079] Power supplies 116a and 116b supply a negative DC voltage (bias voltage) or an AC voltage to first electrodes 106a and 106b via low-pass filters 115a and 115b, respectively. The low-pass filters 115a and 115b block the high frequencies supplied from baluns 103a and 103b so that they are not transmitted to the power supplies 116a and 116b. By supplying a negative DC voltage from the power supplies 116a and 116b to the first electrodes 106a and 106b, respectively, the voltage on the surfaces of targets 109a and 109b can be controlled. By supplying an AC voltage from the power supplies 116a and 116b to the first electrodes 106a and 106b, respectively, the energy of the ions colliding with the surfaces of targets 109a and 109b can be controlled. A DC power supply 304 supplies a DC voltage (bias voltage) to a third electrode 151 via a low-pass filter 303. The low-pass filter 303 blocks the high frequencies supplied from a high-frequency power supply 301 so that they are not transmitted to the DC power supply 304. When the DC power supply 304 supplies a DC voltage to the third electrode 151, the surface potential of the substrate 112 can be controlled.

[0080] Each of the first high-frequency supply unit and the second high-frequency supply unit can be represented by an equivalent circuit similar to the equivalent circuit shown in Figure 3 In the sixth embodiment, it is also preferably satisfied that 1.5 ≤ X / Rp ≤ 5000.

[0081] In the sixth embodiment, the relationship between the size of the first electrode 106a and the size of the second electrode 135a is not limited either. However, the first electrode 106a and the second electrode 135a preferably have similar sizes. Similarly, the relationship between the size of the first electrode 106b and the size of the second electrode 135b is not limited. However, the first electrode 106b and the second electrode 135b preferably have similar sizes.

[0082] The present invention is not limited to the above embodiments, and various changes and modifications can be made without departing from the spirit and scope of the present invention. Therefore, in order to make the scope of the present invention public, the following claims are attached.

[0083] Reference Signs

[0084] 1: Plasma processing apparatus, 10: Main body, 101: High-frequency power supply, 102: Impedance matching circuit, 103: Balun, 104: Blocking capacitor, 106: First electrode, 107, 108: Insulator, 109: Target, 110: Vacuum chamber, 111: Second electrode, 112: Substrate, 115: Low-pass filter, 116: Power supply, 201: First unbalanced terminal, 202: Second unbalanced terminal, 211: First balanced terminal, 212: Second balanced terminal, 213: Midpoint terminal, 251: First terminal, 252: Second terminal, 253: Third terminal, 221: First coil, 222: Second coil, 223: Third coil, 224: Fourth coil.

Claims

1. A plasma processing apparatus, characterized in that, Comprising: A balun, including a first unbalanced terminal, a second unbalanced terminal, a first balanced terminal, and a second balanced terminal; A grounded vacuum chamber; A first electrode electrically connected to the first balanced terminal; A second electrode electrically connected to the second balanced terminal; An impedance matching circuit; A first power supply connected to the balun via the impedance matching circuit and configured to supply high frequency to the first electrode via the impedance matching circuit and the balun; A low-pass filter; And A second power supply configured to supply a voltage to the first electrode via the low-pass filter, wherein, when Rp represents the resistance component between the first balanced terminal and the second balanced terminal when viewed from the side of the first electrode and the second electrode with respect to the first balanced terminal and the second balanced terminal, and X represents the inductance between the first unbalanced terminal and the first balanced terminal, 1.5 ≤ X / Rp ≤ 5000 is satisfied.

2. The plasma processing apparatus according to claim 1, characterized in that, The first electrode holds a target, and the second electrode holds a substrate.

3. The plasma processing apparatus according to claim 1, wherein The balun includes a first coil configured to connect the first unbalanced terminal and the first balanced terminal and a second coil configured to connect the second unbalanced terminal and the second balanced terminal.

4. The plasma processing apparatus according to claim 3, wherein The balun further includes a third coil and a fourth coil both connected between the first balanced terminal and the second balanced terminal, and the third coil and the fourth coil are configured to set the voltage of the connection node between the third coil and the fourth coil to the midpoint between the voltage of the first balanced terminal and the voltage of the second balanced terminal.

5. The plasma processing apparatus according to claim 4, wherein The connection node is connected to the vacuum chamber.

6. The plasma processing apparatus according to claim 1, wherein The second power supply includes an AC power supply, and The frequency of the voltage supplied from the AC power supply to the first electrode is lower than the frequency of the high frequency generated by the first power supply.

7. The plasma processing apparatus according to claim 1, wherein The first electrode is supported by the vacuum chamber via an insulator.

8. The plasma processing apparatus according to claim 1, wherein, The insulator is disposed between the second electrode and the vacuum chamber.

9. The plasma processing apparatus according to claim 1, wherein Further includes at least one of a mechanism configured to vertically move the second electrode and a mechanism configured to rotate the second electrode.

10. The plasma processing apparatus according to claim 1, characterized in that, The first electrode holds a substrate, and the plasma processing apparatus is configured as an etching apparatus.

11. The plasma processing apparatus according to claim 1, wherein The first electrode holds a target, and the second electrode is disposed around the first electrode.

12. The plasma processing apparatus according to claim 1, wherein A plurality of high-frequency supply units are provided, and each of the plurality of high-frequency supply units includes a balun, a first electrode, and a second electrode, and The first electrode of each of the plurality of high-frequency supply units holds a target, and in each of the plurality of high-frequency supply units, the second electrode is disposed around the first electrode.

13. The plasma processing apparatus according to claim 11, wherein, The first electrode and the second electrode are supported by the vacuum chamber via an insulator.

14. The plasma processing apparatus according to claim 11, wherein Further includes: A third electrode configured to hold a substrate; And A second high-frequency power supply configured to supply high frequency to the third electrode via a second impedance matching circuit.

15. The plasma processing apparatus according to claim 14, wherein, Further includes: A second DC power supply is configured to supply a DC voltage to the third electrode via a second low-pass filter.

16. The plasma processing apparatus according to claim 14, characterized in that, An insulator is disposed between the third electrode and the vacuum container.

17. The plasma processing apparatus according to claim 14, wherein, It further includes at least one of a mechanism configured to vertically move the third electrode and a mechanism configured to rotate the third electrode.

18. The plasma processing apparatus according to any one of claims 1 to 17, characterized in that, The first balance terminal is electrically connected to the first electrode via a blocking capacitor.

19. The plasma processing apparatus according to any one of claims 1 to 17, characterized in that, The second balance terminal is electrically connected to the second electrode via a blocking capacitor.

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