Plasma processing equipment

Abstract

To provide a plasma processing apparatus capable of increasing the in-plane uniformity of plasma processing.SOLUTION: A plasma processing apparatus comprises a chamber, a first lower electrode, a second lower electrode, a first upper electrode, a second upper electrode, and a first power source. The first lower electrode is provided inside of the chamber, and has a board mounting area on which a board is to be mounted. The second lower electrode is arranged in an area outside of the board mounting area. The first upper electrode is arranged facing the board mounting area. The second upper electrode is arranged in an area outside of the first upper electrode and arranged facing the second lower electrode. The first power source supplies a signal with periodicity to the first lower electrode. At least one of the second lower electrode and the second upper electrode has a recess. The second lower electrode or the second upper electrode is located on the normal line to the surface of the recess.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] The plasma processing apparatuses disclosed in Patent Document 1 and Patent Document 2 provide a stepped slope in the peripheral portion of the upper electrode to increase the plasma density in the peripheral portion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2004-511906 [Patent Document 2] Japanese Patent Application Laid-Open No. 2009-239014 Summary of the Invention [Problem to be solved by the invention]

[0004] According to the above-mentioned document, by providing a sloped step on the periphery of the upper electrode, electrons can be concentrated near the corners of the slope, thereby efficiently generating plasma. On the other hand, there is a demand for a plasma processing apparatus that can improve the in-plane uniformity of plasma. [Means for solving the problem]

[0005] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a first lower electrode, a second lower electrode, a first upper electrode, a second upper electrode, and a first power supply. The first lower electrode is provided inside the chamber and has a substrate mounting area on which a substrate is mounted. The second lower electrode is disposed in an area outside the substrate mounting area. The first upper electrode is disposed opposite the substrate mounting area. The second upper electrode is disposed in an area outside the first upper electrode and opposite the second lower electrode. The first power supply supplies a periodic signal to the first lower electrode. At least one of the second lower electrode and the second upper electrode has a flat portion. The semiconductor device further includes a second power supply that supplies a periodic signal to the second upper electrode, a first power supply line that supplies the periodic signal output from the second power supply to the first upper electrode, and a second power supply line that supplies the periodic signal output from the second power supply to the second upper electrode, a variable impedance circuit on the first power supply line or the second power supply line, and further includes a sensor that measures a self-bias voltage or a voltage waveform generated in the second lower electrode or the second upper electrode, and a control unit that controls the impedance of the variable impedance circuit in accordance with the measurement value measured by the sensor. [Effects of the Invention]

[0006] According to the plasma processing apparatus, the in-plane uniformity of the plasma can be improved. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram showing a basic structure of a plasma processing apparatus according to an exemplary embodiment; [Figure 2] 1 is a diagram showing a vertical cross-sectional configuration of a basic structure of a main part of a plasma processing apparatus according to an exemplary embodiment; [Figure 3] 10 is a graph showing the relationship between vertical position Z and potential V(au). [Figure 4] 1 is a diagram showing a longitudinal cross-sectional configuration of a main part of a plasma processing apparatus according to an exemplary embodiment; [Figure 5] 1 is a diagram showing a longitudinal cross-sectional configuration of a main part of a plasma processing apparatus according to an exemplary embodiment; [Figure 6] 1 is a diagram showing a vertical cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus according to an exemplary embodiment; [Figure 7] 1 is a diagram showing a vertical cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus according to an exemplary embodiment; [Figure 8] FIG. 4 is a diagram showing an example of the positional relationship between an auxiliary electrode and a second electrode plate. [Figure 9]1 is a diagram showing a vertical cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus according to an exemplary embodiment; [Figure 10] 1 is a diagram showing a vertical cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus according to an exemplary embodiment; [Figure 11] 1 is a diagram showing a vertical cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus according to an exemplary embodiment; [Figure 12] 1 is a diagram showing a vertical cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus according to an exemplary embodiment; [Figure 13] 1 is a diagram showing a vertical cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus according to an exemplary embodiment; [Figure 14] 1 is a diagram showing a longitudinal cross-sectional configuration of a main part of a plasma processing apparatus according to an exemplary embodiment; [Figure 15] FIG. 4 is a diagram showing an example of the positional relationship between an auxiliary electrode and a second electrode plate. [Figure 16] FIG. 2 is a diagram showing the connection relationship between a power supply and electrodes. DETAILED DESCRIPTION OF THE INVENTION

[0008] Various exemplary embodiments are described below.

[0009] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a first lower electrode, a second lower electrode, a first upper electrode, a second upper electrode, and a first power supply. The first lower electrode is provided inside the chamber and has a substrate mounting area on which a substrate is mounted. The second lower electrode is disposed in an area outside the substrate mounting area (hereinafter referred to as a substrate peripheral area). The first upper electrode is disposed opposite the substrate mounting area. The second upper electrode is disposed in an area outside the first upper electrode and opposite the second lower electrode. The first power supply supplies a periodic signal to the first lower electrode. At least one of the second lower electrode and the second upper electrode has a recess. The second lower electrode or the second upper electrode is located on a normal to the surface of the recess.

[0010] At least one of the second lower electrode and the second upper electrode has a recess. Electrons accelerated from near the surface of one recess toward the other are focused, increasing the plasma density in the peripheral region of the substrate and preventing the plasma density from increasing in the central region of the substrate-mounting region. This improves the in-plane uniformity of the plasma.

[0011] In one exemplary embodiment, both the second lower electrode and the second upper electrode may have recesses. The recesses of the second upper electrode may be located on a normal to the surface of the recesses of the second lower electrode, and the recesses of the second lower electrode may be located on a normal to the surface of the recesses of the second upper electrode. In the second lower electrode and the second upper electrode, electrons accelerated from near the surface of one recess toward the other recess are focused. Conversely, electrons accelerated from near the surface of the other recess toward one recess are also focused. Therefore, the plasma density in the peripheral region of the substrate is increased. This makes it possible to suppress an increase in plasma density in the center of the substrate mounting region. Therefore, the in-plane uniformity of the plasma can be improved.

[0012] In one exemplary embodiment, the plasma processing apparatus may further include a second power supply that supplies a DC voltage to the second upper electrode. Supplying a DC voltage to the second upper electrode exerts a force on electrons moving toward the second upper electrode, thereby controlling the plasma density in the vicinity of the second upper electrode. Applying a repulsive force to the electrons moves them away from the second upper electrode, increasing the plasma density in the peripheral region of the substrate. This allows the ratio of the plasma density in the center of the substrate mounting area to the plasma density in the peripheral region of the substrate to be adjusted. This improves the in-plane uniformity of the plasma.

[0013] In one exemplary embodiment, the plasma processing apparatus may further include a third power supply that supplies a periodic signal to the second upper electrode. When the periodic signal is supplied to the second upper electrode, the density of the plasma generated near the second upper electrode can be improved. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0014] In one exemplary embodiment, the plasma processing apparatus may include a first power supply line and a second power supply line. The first power supply line supplies a periodic signal output from a third power supply to the first upper electrode. The second power supply line supplies a periodic signal output from the third power supply to the second upper electrode. A variable impedance circuit may be provided in the first power supply line or the second power supply line.

[0015] By adjusting the impedance in the variable impedance circuit, the amount of power supplied to the target upper electrode can be adjusted. Therefore, the ratio of power supplied to the first upper electrode and the second upper electrode can be adjusted. Plasma density depends on the amount of power supplied to the target electrodes. Therefore, by adjusting the ratio of the power supplies, the in-plane uniformity of the plasma can be improved.

[0016] In one exemplary embodiment, the plasma processing apparatus may further include a fourth power supply that supplies a DC voltage to the second lower electrode. Supplying a DC voltage to the second lower electrode applies a force to electrons moving toward the second lower electrode, thereby controlling the plasma density in the vicinity of the second lower electrode. Applying a repulsive force to the electrons moves them away from the second lower electrode, increasing the plasma density in the peripheral region of the substrate. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0017] In one exemplary embodiment, the plasma processing apparatus may include a third power supply line and a fourth power supply line. The third power supply line supplies the periodic signal output from the first power supply to the first lower electrode. The fourth power supply line supplies the periodic signal output from the first power supply to the second lower electrode. The plasma processing apparatus may include a variable impedance circuit in the third power supply line or the fourth power supply line.

[0018] By adjusting the impedance in the variable impedance circuit, the amount of power supplied to the target lower electrode can be adjusted. Therefore, the ratio of power supplied to the first lower electrode and the second lower electrode can be adjusted. Plasma density depends on the amount of power supplied to the target electrodes. Therefore, by adjusting the ratio of the power supplies, the in-plane uniformity of the plasma can be improved.

[0019] In one exemplary embodiment, the plasma processing apparatus may further include a fifth power supply that supplies a periodic signal to the second lower electrode. When the periodic signal is supplied to the second lower electrode, the density of the plasma generated near the second lower electrode can be improved. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0020] In one exemplary embodiment, the plasma processing apparatus may further include a sensor that measures a self-bias voltage or a voltage waveform generated in the second lower electrode or the second upper electrode. The plasma processing apparatus may also include a control unit that controls the impedance of the variable impedance circuit in accordance with a measurement value measured by the sensor.

[0021] The impedance of the variable impedance circuit controls the plasma density generated in the space above the substrate placement area (the space between the first lower electrode and the first upper electrode) and the space above the substrate peripheral area (the space between the second lower electrode and the second upper electrode). The measurement value obtained by the sensor correlates with the plasma density in the substrate peripheral area. Therefore, the control unit can adjust the amount of power supplied to the electrode connected to the variable impedance circuit by adjusting the impedance of the variable impedance circuit according to the plasma density corresponding to the measurement value. The plasma density depends on the amount of power supplied to the electrode in question. Therefore, the in-plane uniformity of the plasma can be improved by adjusting the ratio of the power supply amounts based on the measurement value obtained by the sensor.

[0022] In one exemplary embodiment, the plasma processing apparatus may further include a sensor that measures a self-bias voltage or a voltage waveform generated in the second lower electrode, and a control unit that controls the output of the second power supply in accordance with a measurement value measured by the sensor.

[0023] The measurement value obtained by the sensor correlates with the amount of electrons reflected by the second lower electrode, i.e., the plasma density in the peripheral region of the substrate. Furthermore, the plasma density can be adjusted by adjusting the output of the second power supply. Therefore, the control unit can control the plasma density in the peripheral region of the substrate by adjusting the output of the second power supply in accordance with the plasma density corresponding to the measurement value. Therefore, the in-plane uniformity of the plasma can be improved.

[0024] In one exemplary embodiment, the plasma processing apparatus may further include a sensor that measures a self-bias voltage or a voltage waveform generated in the second lower electrode, and a control unit that controls an output of the fifth power supply in accordance with a measurement value measured by the sensor.

[0025] The measurement value obtained by the sensor correlates with the amount of electrons reflected by the second lower electrode, i.e., the plasma density in the peripheral region of the substrate. When the control unit adjusts the output of the fifth power supply in accordance with the plasma density corresponding to the measurement value, the plasma density in the peripheral region of the substrate can be controlled. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0026] In one exemplary embodiment, the control unit may control the output of the second power supply so that a negative DC voltage greater than or equal to the self-bias voltage generated in the second lower electrode is generated in the second upper electrode.

[0027] When a negative DC voltage is applied to the second upper electrode, electrons heading toward the second upper electrode are repulsed and reflected. The reflected electrons proceed to the plasma region and contribute to plasma generation, increasing the plasma density in the region surrounding the substrate. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0028] In one exemplary embodiment, the second lower electrode and the second upper electrode may be electrically grounded. When a plasma sheath with a positive potential is formed between the second lower electrode and the second upper electrode, electrons near these electrodes travel toward the sheath. The electrons moving toward the sheath contribute to plasma generation, increasing the plasma density in the region surrounding the substrate. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0029] In one exemplary embodiment, the distance between the second upper electrode and the second lower electrode may be narrower than the distance between the first upper electrode and the first lower electrode. This strengthens the electric field in the region around the substrate (the region between the second upper electrode and the second lower electrode), thereby increasing the plasma density in this region. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0030] In one exemplary embodiment, the plasma processing apparatus may include a conductive edge ring between the substrate mounting area on which the substrate is mounted and the second lower electrode. The edge ring can adjust the electric field around the periphery of the substrate mounting area, thereby improving the uniformity of the plasma processing.

[0031] In one exemplary embodiment, the second upper electrode and the second lower electrode may be arranged so that the normal to the bottom surface of the recess is inclined with respect to the normal to the substrate mounting area. By changing the distance between the second upper electrode and the second lower electrode and / or the inclination angle, the intensity and shape of the plasma in the peripheral area of ​​the substrate can be changed. This improves the design freedom of the in-plane distribution of plasma density, thereby improving the in-plane uniformity of the plasma.

[0032] In one exemplary embodiment, the second upper electrode may be configured as an inner wall of the chamber or a deposit shield provided along the inner wall of the chamber. In this case, the second upper electrode also serves as the inner wall of the chamber or the deposit shield, thereby achieving the above-mentioned advantageous effects while reducing the number of parts.

[0033] Various exemplary embodiments will be described in detail below with reference to the drawings. Note that the same or equivalent parts in the drawings will be denoted by the same reference numerals, and redundant explanations will be omitted.

[0034] FIG. 1 is a diagram showing the basic structure of a plasma processing apparatus 1 according to an exemplary embodiment. The plasma processing apparatus 1 in this embodiment is, for example, a capacitively coupled parallel plate plasma etching apparatus. The plasma processing apparatus 1 has a substantially cylindrical chamber 10 formed, for example, of aluminum whose surface has been anodized. The chamber 10 is protectively grounded.

[0035] A cylindrical support table 14 is disposed on the bottom of the chamber 10 via an insulating plate made of ceramics or the like. A mounting table 16 made of aluminum or the like is provided on the support table 14. The mounting table 16 functions as a lower electrode (first lower electrode).

[0036] The mounting table 16 has a substrate mounting area on which a substrate is placed. An electrostatic chuck 18 is provided on the upper surface of the mounting table 16. The electrostatic chuck 18 attracts and holds a semiconductor wafer W, which is an example of a substrate, by electrostatic force. The electrostatic chuck 18 has a structure in which an electrode 20 formed of a conductive film is sandwiched between a pair of insulating layers or insulating sheets. A DC power supply SG is electrically connected to the electrode 20. The semiconductor wafer W is placed on the upper surface of the electrostatic chuck 18 and is attracted and held by the electrostatic chuck 18 by electrostatic force generated by a DC voltage supplied from the DC power supply SG. The upper surface of the electrostatic chuck 18 on which the semiconductor wafer W is placed is an example of a substrate mounting area of ​​the mounting table 16.

[0037] An edge ring ER is provided on the upper surface of the mounting table 16. The edge ring ER is provided to surround the substrate mounting area. The edge ring ER has an annular shape and is arranged so that the vertical central axis of the electrostatic chuck 18 coincides with the vertical central axis of the edge ring ER. The edge ring ER is made of a conductive material such as silicon. The edge ring ER may be arranged on the electrostatic chuck 18. When viewed from above, the edge ring ER is provided between the substrate mounting area and the auxiliary electrode AUX. The edge ring ER can adjust the electric field so that active species move vertically (perpendicular to the substrate surface) around the periphery of the substrate mounting area. The edge ring ER improves the uniformity of plasma processing such as etching. An insulating member 26 including a cylindrical inner wall member made of, for example, quartz is provided on the side surfaces of the mounting table 16 and the support table 14. The insulating member 26 can be composed of multiple parts, and conductive wiring can also be arranged inside.

[0038] The auxiliary electrode AUX is an annular member provided on the outer periphery of the edge ring ER, and is disposed so that the vertical central axis of the electrostatic chuck 18 coincides with the vertical central axis of the auxiliary electrode AUX. That is, the auxiliary electrode AUX is disposed concentrically with the edge ring ER, and is disposed in a region (substrate peripheral region) outside the substrate mounting region. The auxiliary electrode AUX is formed of a conductive material such as silicon, and is placed on an insulating member 26.

[0039] An annular coolant chamber, for example, is formed inside the mounting table 16. A coolant such as cooling water at a predetermined temperature is circulated and supplied into this coolant chamber from an external chiller unit via piping. The coolant circulating inside the coolant chamber controls the temperatures of the mounting table 16 and the electrostatic chuck 18, and the semiconductor wafer W on the electrostatic chuck 18 is controlled to a predetermined temperature.

[0040] Furthermore, a heat transfer gas such as He gas is supplied from a heat transfer gas supply mechanism (not shown) between the upper surface of the electrostatic chuck 18 and the rear surface of the semiconductor wafer W through piping inside the mounting table 16 .

[0041] An upper electrode 34 is provided above the mounting table 16, which functions as a lower electrode, so as to face the mounting table 16. The space between the upper electrode 34 and the mounting table 16 serves as a plasma generation space, and plasma PL is generated within this space.

[0042] The upper electrode 34 is supported on the upper part of the chamber 10 via an insulating shielding member 42. The insulating shielding member 42 may be a cylindrical insulating member having a step formed on its inner surface for support. The upper electrode 34 includes a first electrode plate 36 (first upper electrode), a second electrode plate 35 (second upper electrode), and an electrode support 38. The first electrode plate 36 forms a surface facing the mounting table 16 and has a number of discharge holes 37. The first electrode plate 36 and the second electrode plate 35 are preferably made of a low-resistance conductor or semiconductor with low Joule heat, such as silicon or SiC. The second electrode plate 35 has an annular shape and is concentrically disposed around the first electrode plate 36 so as to surround the first electrode plate 36. The first electrode plate 36 is disposed above the edge ring ER and the electrostatic chuck 18. The second electrode plate 35 is disposed above the auxiliary electrode AUX. The second electrode plate 35 is insulated from the first electrode plate 36 by an insulating member 39. When high-frequency power is applied to the upper electrode 34, the insulating member 39 may be formed thin so that high-frequency current can flow through it. The illustrated first electrode plate 36 and second electrode plate 35 are merely examples, and various modifications are possible.

[0043] The electrode support 38 detachably supports the first electrode plate 36 and the second electrode plate 35. The electrode support 38 has a water-cooled structure formed of a conductive material such as aluminum whose surface has been anodized. A gas diffusion chamber 40 is provided inside the electrode support 38. A number of gas circulation holes 41 that communicate with the discharge holes 37 extend downward from the gas diffusion chamber 40.

[0044] A gas inlet 62 is formed in the electrode support 38 to introduce a process gas into the gas diffusion chamber 40, and a gas supply pipe 64 is connected to the gas inlet 62. A process gas supply source 66 is connected to the gas supply pipe 64 via a valve 70 and a mass flow controller (MFC) 68. When etching a semiconductor wafer W, the process gas supply source 66 supplies a process gas for etching to the gas diffusion chamber 40 via the gas supply pipe 64. The process gas supplied into the gas diffusion chamber 40 diffuses within the gas diffusion chamber 40 and is discharged in a shower-like manner into the plasma processing space through the gas circulation holes 41 and the discharge holes 37. That is, the upper electrode 34 also functions as a showerhead for supplying the process gas into the plasma processing space.

[0045] A power supply SB is electrically connected to the second electrode plate 35 via a low-pass filter (LPF) 46 and a switch 47. In this example, the power supply SB is a variable DC power supply. The power supply SB outputs a negative DC voltage of a magnitude (absolute value) instructed by the control unit 95. The switch 47 controls the supply and cut-off of the negative DC voltage from the power supply SB to the second electrode plate 35.

[0046] The control unit 95 can be configured from a central processing unit (CPU) of a computer, and can execute processing steps stored in the memory unit 97. If the user interface 96 is an input device such as a keyboard or buttons, commands can be input from the input device to the control unit 95. If the user interface 96 is an output device such as a display, the processing results from the control unit 95 can be displayed.

[0047] A cylindrical ground conductor 10a is provided on the side wall of the chamber 10 above the height position of the upper electrode 34. The ground conductor 10a has a ceiling wall on its top.

[0048] A power supply SA is electrically connected to the mounting table 16, which functions as a lower electrode, via a first matching box 87. In this example, the power supply SA is a high-frequency power supply that generates a periodic signal. In this specification, a periodic signal refers to an electrical signal having a periodically changing voltage waveform and current waveform, and is output from a high-frequency power supply or a pulsed power supply. It also includes an electrical signal obtained by amplifying a periodic signal using an amplifier. A power supply SF is electrically connected to the mounting table 16 via a second matching box 88. The power supply SF in this example is also a high-frequency power supply that generates a periodic signal, but its power frequency is different from that of the power supply SA. The power supply SA is a power supply for plasma generation and outputs a first high-frequency power with a frequency of 13 MHz or higher, e.g., 40 MHz. The power supply SF is a power supply for ion attraction and outputs a second high-frequency power with a frequency lower than that of the power supply SA and lower than 27 MHz, e.g., 2 MHz. Instead of the power supply SF, a pulsed power supply that periodically outputs a negative-polarity pulsed voltage may be used as a power supply that generates a periodic signal. The pulse power supply may be a DC pulse power supply that periodically outputs a negative DC voltage, or an impulse power supply that instantaneously and periodically outputs a negative voltage.

[0049] The first matching device 87 matches the impedance of the power supply SA with the load impedance so that the impedance of the power supply SA and the load impedance appear to match when plasma is generated in the chamber 10. Similarly, the second matching device 88 matches the impedance of the power supply SF with the load impedance so that the impedance of the power supply SF and the load impedance appear to match when plasma is generated in the chamber 10.

[0050] An exhaust port is provided at the bottom of chamber 10, and an exhaust device 84 is connected to the exhaust port via an exhaust pipe. The exhaust device 84 has a vacuum pump such as a turbomolecular pump, and can reduce the pressure inside chamber 10 to a desired vacuum level. An opening 85 for loading and unloading a semiconductor wafer W is also provided in the sidewall of chamber 10, and opening 85 can be opened and closed by a gate valve 86.

[0051] A deposit shield is provided along the inner wall of the chamber 10 to prevent etching by-products (deposits) from adhering to the inner wall of the chamber 10. A deposit shield is also provided around the outer periphery of the insulating member 26. An exhaust plate (not shown) is provided between the deposit shield on the chamber wall side at the bottom of the chamber 10 and the deposit shield on the insulating member 26 side. The deposit shield and exhaust plate can be made of, for example, aluminum coated with ceramics such as Y2O3. The deposit shield can be electrically connected to ground potential (ground), preventing abnormal discharge within the chamber 10.

[0052] Each component of the plasma processing apparatus 1 is controlled by a control unit 95. A user interface 96 including a keyboard through which a process manager inputs commands to manage the plasma processing apparatus 1, a display that visualizes the operating status of the plasma processing apparatus 1, and the like is connected to the control unit 95.

[0053] The programs include a control program for realizing various processes executed in the plasma processing apparatus 1 under the control of the control unit 95, and a program for causing each component of the plasma processing apparatus 1 to execute a process according to processing conditions. These programs and recipes indicating the processing conditions are stored in a memory unit 97, which is connected to the control unit 95. The memory unit 97 is, for example, a hard disk or a semiconductor memory. The memory unit 97 may also be a portable storage medium readable by a computer. In this case, the control unit 95 acquires the control program and the like stored in the storage medium via a device that reads data from the storage medium. The storage medium is, for example, a CD-ROM or a DVD.

[0054] The control unit 95 reads out and executes any recipe from the storage unit 97 in response to an instruction from a user via the user interface 96, thereby controlling each unit of the plasma processing apparatus 1 and performing a predetermined plasma processing on the semiconductor wafer W. The plasma processing apparatus 1 in this embodiment includes the control unit 95, the user interface 96, and the storage unit 97.

[0055] When etching a semiconductor wafer W in the plasma processing apparatus 1 configured as described above, first, the gate valve 86 is controlled to an open state, and the semiconductor wafer W to be etched is loaded into the chamber 10 through the opening 85. Next, the semiconductor wafer W is placed on the electrostatic chuck 18. Then, a predetermined DC voltage is applied to the electrostatic chuck 18 from the DC power supply SG, and the semiconductor wafer W is attracted and held on the upper surface of the electrostatic chuck 18.

[0056] Then, a processing gas for etching or the like is supplied at a predetermined flow rate from processing gas supply source 66 to gas diffusion chamber 40, and the processing gas is supplied into chamber 10 via gas circulation holes 41 and outlet holes 37. Furthermore, chamber 10 is evacuated by exhaust device 84, and the pressure within chamber 10 is controlled to a predetermined pressure. With processing gas being supplied into chamber 10, high-frequency power for plasma generation is applied to mounting table 16 from power supply SA, and high-frequency power for ion attraction is applied to mounting table 16 from power supply SF. Furthermore, a negative DC voltage (potential) of a predetermined magnitude is applied to second electrode plate 35 from power supply SB.

[0057] The processing gas discharged from the discharge holes 37 of the upper electrode 34 is converted into plasma between the upper electrode 34 and the mounting table 16 by the high-frequency power applied to the mounting table 16. The radicals and ions generated by this plasma etch the semiconductor wafer W. The above processing is performed in response to instructions from the control unit 95.

[0058] Next, the potential of the auxiliary electrode will be described.

[0059] FIG. 2 is a diagram showing a vertical cross-sectional configuration of the basic structure of the main part of the plasma processing apparatus shown in FIG.

[0060] The edge ring ER and auxiliary electrode AUX are mounted on an insulating member 26 made of multiple components such as a quartz ring. The portion of the insulating member 26 on which the edge ring ER is mounted is thin, allowing high-frequency current from the power supplies SA and SF to flow to the edge ring ER via the mounting table 16. The auxiliary electrode AUX is coupled to the edge ring ER via a parasitic capacitance C. Furthermore, if the portion of the insulating member 26 on which the auxiliary electrode AUX is mounted is thin, high-frequency current from the power supplies SA and SF flows to the auxiliary electrode AUX via the mounting table 16. Therefore, the auxiliary electrode AUX has a periodically fluctuating potential. Furthermore, a self-bias voltage, which is a negative DC voltage, is generated in the auxiliary electrode AUX, and the potential of the auxiliary electrode AUX periodically fluctuates based on the self-bias voltage Vdc.

[0061] A DC voltage of −V2 is applied from a power supply SB to the second electrode plate 35 facing the auxiliary electrode AUX. Electrons having a negative charge (−) move in response to the electric field between the auxiliary electrode AUX and the plasma and the electric field between the plasma and the second electrode plate 35.

[0062] 3 is a graph showing the relationship between vertical position Z and potential V(au), and schematically illustrates the potential distribution between the auxiliary electrode AUX and the second electrode plate 35. Note that the vertically upward direction of the plasma processing apparatus is the positive direction of the Z axis, and each potential indicates a voltage relative to the ground potential (V=0). In addition, the magnitude (absolute value) of the negative voltage -V2 applied to the second electrode plate 35 can be set to be equal to the magnitude (absolute value) of the self-bias voltage Vdc, which is a negative voltage generated in the auxiliary electrode AUX.

[0063] The potential of the auxiliary electrode AUX periodically varies between a maximum value Vmax and a minimum value Vmin, with the self-bias voltage Vdc as the reference. When the potential of the auxiliary electrode AUX is the self-bias voltage Vdc, the potential distribution is as shown by the solid line. When the potential of the auxiliary electrode AUX is the maximum value Vmax or the minimum value Vmin, the potential distribution is as shown by the dotted line. The sheath thickness between the auxiliary electrode AUX and the plasma varies in accordance with the variation in the potential of the auxiliary electrode AUX.

[0064] When the sheath is thin, electrons present in the plasma near the auxiliary electrode AUX are subjected to a force due to the high electric field perpendicular to the surface of the auxiliary electrode AUX as the sheath thickens. The electrons subjected to this force are accelerated toward the second electrode plate 35 (toward the plasma) facing the auxiliary electrode AUX. Similarly, secondary electrons generated by ion collisions with the auxiliary electrode AUX are also subjected to a force due to the sheath electric field between the auxiliary electrode AUX and the plasma. The electrons subjected to this force are accelerated toward the second electrode plate 35 (toward the plasma). Some of these accelerated electrons collide with particles in the plasma, contributing to an increase in plasma density. Meanwhile, the remaining accelerated electrons that do not collide with particles in the plasma proceed toward the second electrode plate 35.

[0065] Accelerated electrons traveling toward second electrode plate 35 are subjected to a repulsive force by the sheath electric field between second electrode plate 35 and the plasma. The strength of the sheath electric field is proportional to the difference between the plasma potential and the wall potential. Therefore, if the difference between the plasma potential and the potential (wall potential) of second electrode plate 35 is smaller than the difference between the plasma potential and the potential (wall potential) of auxiliary electrode AUX (entry condition), the accelerated electrons will enter second electrode plate 35.

[0066] Furthermore, if the difference between the plasma potential and the potential (wall potential) of the second electrode plate 35 is greater than the difference between the plasma potential and the potential (wall potential) of the auxiliary electrode AUX (reflection condition), the accelerated electrons are subjected to a repulsive force in the direction opposite to the direction toward the second electrode plate 35. In other words, when this reflection condition is satisfied, the accelerated electrons are subjected to a repulsive force greater than the force received from the sheath electric field between the plasma potential and the auxiliary electrode AUX, and are accelerated toward the plasma (toward the auxiliary electrode AUX). Some of the accelerated electrons collide with particles in the plasma, contributing to an increase in plasma density.

[0067] Therefore, the potential of the second electrode plate 35 is set so that the difference between the plasma potential and the potential (wall potential) of the second electrode plate 35 is greater than the difference between the plasma potential and the potential (wall potential) of the auxiliary electrode AUX. This allows electrons that do not collide with particles in the plasma and contribute to improving the plasma density to be returned to the plasma, thereby contributing to improving the plasma density. The potential of the auxiliary electrode AUX periodically fluctuates between a maximum value Vmax and a minimum value Vmin, with the self-bias voltage Vdc as the reference. The plasma potential is higher than the potential of the auxiliary electrode AUX. Therefore, even if the potential of the second electrode plate 35 is ground potential (V=0), during the period when the potential of the auxiliary electrode AUX is positive, the difference between the plasma potential and the potential (wall potential) of the second electrode plate 35 is greater than the difference between the plasma potential and the potential (wall potential) of the auxiliary electrode AUX.

[0068] However, since the period during which the potential of the auxiliary electrode AUX is negative is longer, most of the accelerated electrons that do not collide with particles in the plasma enter the second electrode plate 35 and are unlikely to contribute to improving the plasma density.

[0069] Therefore, in this embodiment, a negative DC voltage -V2 having a magnitude (absolute value) equal to or greater than the magnitude (absolute value) of the negative self-bias voltage Vdc generated at the auxiliary electrode AUX is applied to the second electrode plate 35. By making the magnitude (absolute value) of the negative DC voltage -V2 equal to or greater than the magnitude (absolute value) of the negative self-bias voltage Vdc generated at the auxiliary electrode AUX, at least half of the accelerated electrons that do not collide with particles in the plasma can be returned to the plasma. This makes it possible to efficiently generate plasma even in the peripheral portion of the substrate where the plasma density is low. This improves the uniformity of the plasma.

[0070] As described above, the plasma processing apparatus of this example includes a power supply SB (second power supply) that supplies a DC voltage (-V2) to the second electrode plate 35. When a DC voltage is supplied to the second electrode plate 35, a force is applied to the electrons moving toward the second electrode plate 35, thereby controlling the plasma density in the vicinity of the second electrode plate 35. When a repulsive force is applied to these electrons, the electrons move away from the second electrode plate 35, increasing the plasma density in the peripheral region of the substrate. This makes it possible to adjust the ratio between the plasma density in the center of the substrate mounting region and the plasma density in the peripheral region of the substrate. This therefore makes it possible to improve the in-plane uniformity of the plasma.

[0071] The control unit 95 controls the output of the power supply SB (second power supply) so that a negative DC voltage (-V2) equal to or greater than the self-bias voltage (Vdc) generated at the auxiliary electrode AUX is generated at the second electrode plate 35. Note that the self-bias voltage (Vdc) is negative here. When the negative DC voltage (-V2) is applied to the second electrode plate 35, a repulsive force is exerted on electrons heading toward the second electrode plate 35, causing them to be reflected. The reflected electrons proceed toward the plasma region and contribute to plasma generation, thereby increasing the plasma density in the region surrounding the substrate. This can improve the in-plane uniformity of the plasma. This control can also be applied to all other embodiments.

[0072] Next, the shape of each electrode will be described in detail with reference to FIGS.

[0073] FIG. 4 is a diagram showing a vertical cross-sectional configuration of a main part of the plasma processing apparatus.

[0074] In the basic structure of the plasma processing apparatus shown in FIG. 2, the surfaces of the second electrode plate 35 and the auxiliary electrode AUX are flat. However, in this example, the surface of at least one of the second electrode plate 35 and the auxiliary electrode AUX has a recess D. The other electrode portion may be positioned normal to the surface of one recess D. In the plasma processing apparatus shown in FIG. 4, the lower surface of the second electrode plate 35 is processed into a concave shape to form an annular recess D. The annular recess D surrounds the vertical central axis of the substrate peripheral region. The surface of the recess D is a continuous curved surface such as a paraboloid. The upper surface of the auxiliary electrode AUX shown as an example is a flat surface that is flush with or parallel to the substrate mounting region. The normal to the surface of the recess D of the second electrode plate 35 intersects with the upper surface of the auxiliary electrode AUX. In other words, the auxiliary electrode AUX is positioned normal to the surface of the recess D of the second electrode plate 35.

[0075] In this example, because the lower surface of the second electrode plate 35 has the recess D, the density of intersections between multiple normals to the lower surface of the second electrode plate 35 and the upper surface of the auxiliary electrode AUX increases in the central region in the ring width direction compared to the case of FIG. 2. The central region in the ring width direction is a region of the annular auxiliary electrode AUX located between its outer and inner peripheral regions. Therefore, secondary electrons generated from the second electrode plate 35 and electrons accelerated by the sheath electric field between the second electrode plate 35 and the plasma are accelerated toward the central region in the ring width direction of the auxiliary electrode AUX. Because the accelerated electrons are focused toward the central region in the ring width direction of the auxiliary electrode AUX, an increase in plasma density on the substrate placement region side can be suppressed, and the in-plane uniformity of the plasma can be improved.

[0076] A horizontal plane P including the center position in the width direction (radial direction) of the lower surface of the second electrode plate 35 and the upper surface of the lower auxiliary electrode AUX HZN2 2. In other words, the lower surface of the second electrode plate 35 is located lower than the lower surface of the first electrode plate 36. The horizontal plane P HZN1 There is a distance (shortest distance ΔH1) between the first electrode plate 36 and the second electrode plate 35. This makes it possible to strengthen the electric field at the peripheral portion (second electrode plate 35) more than at the center portion (first electrode plate 36), thereby increasing the plasma density at the peripheral portion and improving the uniformity of the plasma.

[0077] As described above, the distance ΔH2 between the second electrode plate 35 (second lower electrode) and the auxiliary electrode AUX (second lower electrode) is narrower than the distance between the first electrode plate 36 and the mounting table 16 (ΔH1 + ΔH2 + the vertical distance from the surface of the auxiliary electrode AUX to the surface of the mounting table 16). Also, ΔH2<ΔH1+ΔH2. This strengthens the electric field in the region around the substrate (the region between the second electrode plate 35 and the auxiliary electrode AUX), thereby increasing the plasma density in this region. Furthermore, as in the example of FIG. 4, by lowering the height of the second electrode plate 35, the plasma density in the region below the second electrode plate 35 can be increased. Therefore, the in-plane uniformity of the plasma can be improved. This structure can also be applied to all other embodiments.

[0078] The vertical cross-sectional shape of the recess D does not have to be a curved shape.

[0079] FIG. 5 is a diagram showing a longitudinal cross-sectional configuration of the main parts of a plasma processing apparatus, and differs from the apparatus of FIG. 4 only in the shape of the recess D. That is, in this example, in a longitudinal cross section passing through the vertical central axis of the substrate mounting area, the lower surface of the second electrode plate 35 is processed into a shape in which the trapezoidal shape has been removed, forming the recess D. The recess D can also be configured with a tapered surface. The tapered surface is substantially flat within a small area. The intersection of the tapered surface and the longitudinal cross section passing through the vertical central axis of the substrate mounting area is a line segment rather than a curved shape. The outer tapered surface surrounds the vertical central axis of the substrate mounting area, and therefore can have the side shape of a truncated cone tapering vertically upward. Similarly, the inner tapered surface surrounds the vertical central axis of the substrate mounting area, and therefore can have the side shape of a truncated cone tapering vertically downward.

[0080] The inclination angle of the tapered surface can be set to the angle at which a normal to the tapered surface intersects with the auxiliary electrode AUX. Therefore, the auxiliary electrode AUX is located on a normal to the surface (tapered surface) of the recess D of the second electrode plate 35. More preferably, the angle is set so that the intersections of multiple normals to the lower surface of the second electrode plate 35 and the upper surface of the auxiliary electrode AUX are located within the central region in the ring width direction. This central region in the ring width direction is a region of the annular auxiliary electrode AUX located between its outer and inner peripheral regions. Since the intersections of multiple normals to the tapered surface of the second electrode plate 35 and the auxiliary electrode AUX are concentrated within the central region in the ring width direction, the same effects as those in FIG. 4 can be achieved.

[0081] The recess D may be provided in the auxiliary electrode AUX.

[0082] FIG. 6 is a diagram showing a longitudinal cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus. In this example, the auxiliary electrode AUX has a recess D. The shape of the recess D is the same as that of the recess D shown in FIG. 4, except that it is upside down. The surface of the recess D is a continuous curved surface such as a paraboloid. A normal to the surface of the recess D of the auxiliary electrode AUX intersects with the lower surface of the second electrode plate 35. That is, the second electrode plate 35 is located on the normal to the surface of the recess D of the auxiliary electrode AUX. Even if the recess D is provided in the auxiliary electrode AUX, electrons are focused toward the central region of the second electrode plate 35 in the ring width direction. Therefore, it is possible to further prevent the plasma density from becoming high in the central portion of the substrate placement area, thereby improving the in-plane uniformity of the plasma.

[0083] FIG. 7 is a diagram showing a vertical cross-sectional configuration of the periphery of a substrate in a plasma processing apparatus.

[0084] This example also shows a configuration in which the auxiliary electrode AUX has a recess D. The shape of the recess D is the same as that of the recess D shown in FIG. 5 except that it is upside down. The recess D is configured with a tapered surface similar to that shown in FIG. 5. The angle of the tapered surface can be set so that a normal to the tapered surface intersects with the second electrode plate 35. Therefore, the second electrode plate 35 is located on a normal to the surface (tapered surface) of the recess D of the auxiliary electrode AUX. More preferably, the intersection of multiple normals to the upper surface of the auxiliary electrode AUX and the lower surface of the second electrode plate 35 is within a central region in the ring width direction of the second electrode plate 35. This central region in the ring width direction is a region located between the outer peripheral region and the inner peripheral region of the annular second electrode plate 35. This allows for the same effects as those in FIG. 5 to be achieved.

[0085] The recess D may be provided in both the auxiliary electrode AUX and the second electrode plate 35.

[0086] FIG. 8 is a diagram showing an example of the positional relationship between the auxiliary electrode AUX and the second electrode plate 35. As shown in FIG.

[0087] In this example, both the auxiliary electrode AUX and the second electrode plate 25 have a recess D. The recess D of the second electrode plate 35 is located on a normal line NAUX to the surface of the recess D of the auxiliary electrode AUX. In addition, the recess D of the auxiliary electrode AUX is located on a normal line N35 to the surface of the recess D of the second electrode plate 35.

[0088] A plurality of normals (NAUX, NAUXa) can be set to the surface of the recess D in the auxiliary electrode AUX. The central normal NAUX is the normal to the deepest part of the recess D in the auxiliary electrode AUX. The normal NAUX extends toward the deepest part of the recess D in the second electrode plate 35.

[0089] A plurality of normals (N35, N35a) can also be set to the surface of the recess D in the second electrode plate 35. The central normal N35 is the normal to the deepest part of the recess D in the second electrode plate 35. The normal N35 extends toward the deepest part of the recess D in the auxiliary electrode AUX.

[0090] When an XYZ three-dimensional Cartesian coordinate system is set, the horizontal plane is represented by the XY plane. In this example, the longitudinal section passing through the vertical central axis of the substrate mounting area is given by the XZ plane. If this central axis is taken as the Z axis, the shape of the recess D of the auxiliary electrode AUX when viewed from the Z axis direction is a ring centered on the Z axis. The shape of the recess D of the second electrode plate 35 when viewed from the Z axis direction is also a ring centered on the Z axis.

[0091] Electrons near the surface of the recessed portion D of the auxiliary electrode AUX are accelerated in the XZ plane toward the recessed portion D of the second electrode plate 35. The accelerated electrons are focused toward the second electrode plate 35. Conversely, electrons near the surface of the recessed portion D of the second electrode plate 35 are accelerated in the XZ plane toward the recessed portion D of the auxiliary electrode AUX. These accelerated electrons are focused toward the auxiliary electrode AUX. Therefore, the plasma density in the peripheral region of the substrate increases. This makes it possible to suppress an increase in plasma density in the central portion of the substrate mounting region. Therefore, it is possible to improve the in-plane uniformity of the plasma.

[0092] Next, the power supply to the auxiliary electrode will be described.

[0093] In the above, an example has been described in which high-frequency power is supplied to the auxiliary electrode AUX via the edge ring ER or the mounting table 16. However, a configuration in which wiring is connected to the auxiliary electrode AUX and the auxiliary electrode AUX is directly connected to a high-frequency power supply may also be adopted. Alternatively, an electrode may be provided inside the dielectric below the auxiliary electrode AUX, and the electrode may be connected to the high-frequency power supply via wiring. High-frequency power can be supplied to the auxiliary electrode AUX by capacitively coupling the electrode inside the dielectric below the auxiliary electrode AUX with the auxiliary electrode AUX. The power supply connected to the auxiliary electrode AUX may be the power supply SA and / or the power supply SF, or may be a high-frequency power supply, a pulse power supply, or a DC power supply different from the power supplies SA and SF.

[0094] 9 is a diagram showing a vertical cross-sectional configuration of the periphery of a substrate in a plasma processing apparatus according to an exemplary embodiment. This example shows an example in which a plurality of power sources and an auxiliary electrode AUX are connected by wiring.

[0095] The power supply SA is connected to the mounting table 16 via a first matching box 87, a common line L0, and a first branch line L1. The power supply SA is also connected to the auxiliary electrode AUX via the first matching box 87, a common line L0, and a second branch line L2. The common line L0 branches into a first branch line L1 and a second branch line L2, and the second branch line L2 is connected to the auxiliary electrode AUX without passing through the mounting table 16. The power supply SA in this example is a high-frequency power supply for generating plasma.

[0096] The power supply SF is connected to the mounting table 16 via a second matching box 88, a common line L0, and a first branch line L1. The power supply SF is also connected to the auxiliary electrode AUX via a second matching box 88, a common line L0, and a second branch line L2. The power supply SF in this example is a high-frequency power supply for attracting ions.

[0097] A first variable impedance circuit 81 and / or a second variable impedance circuit 82 are provided on the first branch wiring L1 and / or the second branch wiring L2. Each variable impedance circuit may have any configuration as long as its impedance is variable. In one example, the first variable impedance circuit 81 and / or the second variable impedance circuit 82 may include a variable capacitor.

[0098] Furthermore, a sensor 83 that measures the self-bias voltage or voltage waveform generated at the auxiliary electrode AUX may be provided between the auxiliary electrode AUX and the second variable impedance circuit 82. The control unit 95 can also determine the peak-to-peak voltage (Vpp: Volt peak to peak) from this voltage waveform. In this case, the magnitude of the self-bias voltage or peak-to-peak voltage obtained by the sensor 83 may be fed back to the control unit 95 shown in FIG. 1. The control unit 95 shown in FIG. 1 may control the power supply SA, the power supply SF, the power supply SB, the first variable impedance circuit 81, and / or the second variable impedance circuit 82.

[0099] The control unit 95 shown in FIG. 1 controls the output of these power supplies to control the impedance of the variable impedance circuit. For example, when the plasma density in the substrate peripheral region is lower than a reference value, the control unit 95 performs control to increase the plasma density. For example, the control unit 95 reduces the impedance of the second variable impedance circuit 82 so as to increase the amount of power flowing through the second branch wiring L2. Furthermore, as shown in FIG. 3, the control unit 95 increases the magnitude (absolute value) of the negative bias voltage (-V2) output from the power supply SB (FIG. 1). This feedback control can increase the plasma density in the substrate peripheral region. Furthermore, when the plasma density in the substrate peripheral region is equal to or higher than the reference value, the control unit 95 performs control to decrease the plasma density in the opposite manner to the above.

[0100] In the plasma processing apparatus of this example, the first and second high frequency powers are supplied to the auxiliary electrode AUX from the power supplies SA and SF via the second variable impedance circuit 82. This makes it possible to adjust the high frequency power supplied to the central and peripheral portions of the mounting table 16, thereby actively controlling the potential of the auxiliary electrode AUX. This allows for control to further improve the in-plane uniformity of the plasma.

[0101] An electrode may be provided inside the dielectric below the auxiliary electrode AUX, and the various power sources exemplified above may be connected to this electrode instead of the auxiliary electrode AUX.

[0102] The plasma processing apparatus of this example has a power transmission path (third power supply line) passing through the first branch wiring L1 and a power transmission path (fourth power supply line) passing through the second branch wiring L2. The third power supply line supplies a periodic signal output from the power supply SA (first power supply) to the mounting table 16 (first lower electrode). The fourth power supply line supplies the periodic signal output from the power supply SA (first power supply) to the auxiliary electrode AUX (second lower electrode). The plasma processing apparatus has a first variable impedance circuit 81 on the first branch wiring L1. The plasma processing apparatus has a second variable impedance circuit 82 on the second branch wiring L2. Even if only one of these variable impedance circuits is used, the power distribution function can be achieved.

[0103] By adjusting the impedances in the first variable impedance circuit 81 and the second variable impedance circuit 82, the amount of power supplied to the target lower electrode can be adjusted. Therefore, the ratio of power supplied to the mounting table 16 and the auxiliary electrode AUX can be adjusted. The plasma density depends on the amount of power supplied to the target electrode. Therefore, by adjusting the ratio of the power supplies, the in-plane uniformity of the plasma can be improved.

[0104] FIG. 10 is a diagram showing a vertical cross-sectional configuration of the periphery of a substrate in a plasma processing apparatus according to an exemplary embodiment.

[0105] The power supply SA is connected to the mounting table 16 via a first matching box 87. In this embodiment, the power supply SA is a high-frequency power supply for generating plasma. The power supply SA supplies a first high-frequency power to the mounting table 16.

[0106] The power supply SF is connected to the mounting table 16 via a second matching box 88. In this embodiment, the power supply SF is a high-frequency power supply for attracting ions. The power supply SF supplies a second high-frequency power to the mounting table 16.

[0107] The power supply SE is connected to the auxiliary electrode AUX via a sensor 83. The power supply SE controls the potential of the auxiliary electrode AUX. By adjusting the potential of the auxiliary electrode AUX, the plasma density in the region surrounding the substrate can be controlled. Furthermore, by adjusting the output of the plasma generating power supply SA, the plasma density in the substrate placement region can be adjusted. The power supply SE is a power supply different from the power supplies SA and SF, and may be a high-frequency power supply. Furthermore, the power supply SE may be a pulse power supply.

[0108] The plasma processing apparatus of this example includes a power supply SE (fifth power supply) that supplies a periodic signal to the auxiliary electrode AUX. When the periodic signal is supplied to the auxiliary electrode AUX, the density of the plasma generated in the vicinity of the auxiliary electrode AUX can be improved.

[0109] The plasma processing apparatus of this embodiment further includes a sensor 83 that measures the self-bias voltage or voltage waveform generated at the auxiliary electrode AUX. The control unit 95 shown in FIG. 1 may control the output of the power supply SB (second power supply) according to the measurement value obtained by the sensor 83. The measurement value obtained by the sensor 83 correlates with the amount of electrons reflected by the auxiliary electrode AUX, i.e., the plasma density in the peripheral region of the substrate. As described above, the plasma density can be adjusted by adjusting the output of the power supply SB. Therefore, the control unit 95 adjusts the output of the power supply SB according to the plasma density corresponding to the measurement value. For example, if the plasma density corresponding to the measurement value of the sensor 83 is lower than a reference value, the control unit 95 increases the output of the power supply SB (the magnitude of the negative bias voltage). Furthermore, if the plasma density corresponding to the measurement value of the sensor 83 is equal to or greater than the reference value, the control unit 95 decreases the output of the power supply SB (the magnitude of the negative bias voltage). This feedback control allows the plasma density in the peripheral region of the substrate to approach the reference value. Therefore, the in-plane uniformity of the plasma can be improved.

[0110] The plasma processing apparatus of this example includes a sensor 83 that measures the self-bias voltage or voltage waveform generated at the auxiliary electrode AUX. The control unit 95 may control the output of the power supply SE (fifth power supply) according to the measurement value obtained by the sensor 83. The measurement value obtained by the sensor 83 correlates with the amount of electrons reflected by the auxiliary electrode AUX, i.e., the plasma density in the peripheral region of the substrate. The control unit 95 adjusts the output of the power supply SE according to the plasma density corresponding to the measurement value, thereby controlling the plasma density in the peripheral region of the substrate. For example, if the plasma density corresponding to the measurement value of the sensor 83 is lower than a reference value, the output of the power supply SE (the magnitude of the amplitude center voltage of the negative bias voltage and / or the power) is increased. If the plasma density corresponding to the measurement value of the sensor 83 is equal to or greater than the reference value, the output of the power supply SE (the magnitude of the amplitude center voltage of the negative bias voltage and / or the power) is decreased. This allows the plasma density in the peripheral region of the substrate to be controlled to approach the reference value. This feedback control improves the in-plane uniformity of the plasma. The correlation between the reference value and the measured value and the plasma density can be stored in advance in the storage unit 97 of FIG.

[0111] Note that a power supply SD (fourth power supply) that generates a DC voltage can be used instead of the power supply SE (fifth power supply). Also, in addition to the power supply SE, a power supply SD that generates a DC voltage may be connected to the auxiliary electrode AUX. That is, the plasma processing apparatus of this example may include a power supply SD (fourth power supply) that supplies a DC voltage to the auxiliary electrode AUX (second lower electrode).

[0112] Instead of or in addition to the power supply SA connected to the mounting table 16 and generating the first high-frequency power (a periodic signal), a power supply SC (third power supply) shown in Fig. 12 or 16 described below may be connected to the second electrode plate 35. In this case, the output from the power supply SC may be branched as shown in Fig. 12.

[0113] When a DC voltage is supplied to the auxiliary electrode AUX, a force is applied to electrons moving toward the auxiliary electrode AUX, thereby controlling the plasma density near the auxiliary electrode AUX. For example, if the plasma density measured by the sensor 83 is lower than a reference value, the control unit 95 increases the output of the power supply SD (the magnitude of the negative bias voltage). This applies a repulsive force to the electrons, causing them to move away from the auxiliary electrode AUX (toward the plasma). These electrons contribute to plasma generation, so the plasma density in the peripheral region of the substrate increases toward the reference value. Conversely, if the plasma density measured by the sensor 83 is equal to or higher than the reference value, the control unit 95 decreases the output of the power supply SD (the magnitude of the negative bias voltage). In this way, the control unit 95 shown in FIG. 1 controls the plasma density in the peripheral region of the substrate, thereby improving the in-plane uniformity of the plasma density.

[0114] The plasma processing apparatus in this example supplies high-frequency power to the auxiliary electrode AUX using a power supply SE (SD) that is different from the power supplies SA and SF. Therefore, the high-frequency power supplied to the peripheral region of the substrate from the power supply SE (SD) can be adjusted independently of the power supplies SA and SF that generate plasma in the center of the mounting table 16, and the potential of the auxiliary electrode AUX can be actively controlled. Therefore, the plasma can be controlled to have higher in-plane uniformity.

[0115] 11 is a diagram showing a longitudinal cross-sectional configuration of the periphery of a substrate in a plasma processing apparatus according to an exemplary embodiment. As shown in this example, a power supply electrode 73 may be provided inside an insulating member 26 located below the auxiliary electrode AUX. The plasma processing apparatus shown in FIG. 11 has a power supply SE (SD) connected to the power supply electrode 73 via a sensor 83, instead of the auxiliary electrode AUX in FIG. 10. The configuration of FIG. 11 is the same as that shown in FIG. 10, except that the potential applied to the auxiliary electrode AUX is controlled via the electrode 73, and similar effects are achieved.

[0116] That is, the electrode 73 is connected to a power supply SE (SD). A sensor 83 for measuring the self-bias voltage or voltage waveform generated in the auxiliary electrode AUX may be provided between the electrode 73 and the power supply SE (SD). The sensor 83 may be directly connected to the auxiliary electrode AUX. The self-bias voltage or voltage waveform (or the magnitude of the peak-to-peak voltage) obtained by the sensor 83 may be fed back to the control unit 95 (FIG. 1) to control the plasma density as in the case of FIG. 10. The control unit 95 may control the output of the power supply SE (SD) or the power supply SB (FIG. 1).

[0117] The plasma processing apparatus in this example supplies high-frequency power to the auxiliary electrode AUX using a power supply SE (SD) that is different from the power supplies SA and SF. Therefore, the high-frequency power supplied to the peripheral region of the substrate from the power supply SE (SD) can be adjusted independently of the power supplies SA and SF that generate plasma in the center of the mounting table 16, and the potential of the auxiliary electrode AUX can be actively controlled. Therefore, the plasma can be controlled to have higher in-plane uniformity.

[0118] Various types of connection between the auxiliary electrode AUX and the power supply are possible. For example, a power supply SE that generates high-frequency power is connected to the electrode 73. Alternatively, a power supply SD that generates a DC voltage is connected to the electrode 73 instead of the power supply SE that generates high-frequency power. Alternatively, the power supply SE that generates a high-frequency voltage may be connected to the electrode 73, and the power supply SD that generates a DC voltage may be connected to the auxiliary electrode AUX.

[0119] The power supply SD may be a DC power supply. The potential of the auxiliary electrode AUX (voltage between it and the ground potential) fluctuates periodically with reference to the self-bias voltage Vdc (amplitude center voltage) shown in FIG. 3 . Therefore, the average value of the potential of the auxiliary electrode AUX is Vdc. The potential of the auxiliary electrode AUX can be varied by directly connecting it to an AC power supply. Alternatively, the potential of the auxiliary electrode AUX can be varied by coupling it to the AC potential applied to the mounting table 16. Here, when a negative DC voltage Va is applied to the electrode 73 by the power supply SD, the average value of the potential of the auxiliary electrode AUX becomes the sum of Vdc and Va. In other words, by connecting the power supply SD, which is a DC power supply, to the electrode 73 or the auxiliary electrode AUX, the periodically fluctuating potential of the auxiliary electrode AUX can be corrected overall.

[0120] It is also possible to configure both the power source SE and the power source SD as high frequency power sources. In this case, the first and second high frequency powers are applied to the auxiliary electrode AUX or the electrode 73.

[0121] In the above, an example has been described in which a DC voltage is applied from power supply SB to second electrode plate 35. Instead of power supply SB that generates a DC voltage, power supply SC that generates an AC voltage can also be connected to second electrode plate 35. Next, a case in which high-frequency power is applied to second electrode plate 35 will be described.

[0122] 12 is a diagram showing a longitudinal cross-sectional configuration of the periphery of a substrate in a plasma processing apparatus according to an exemplary embodiment. In the plasma processing apparatus of this example, the power supply SA for plasma generation shown in FIG. 11 is removed from the mounting table 16, and instead, the power supply SC is connected to the second electrode plate 35 and the electrode support 38 (first electrode plate 36). In other words, this example shows an example in which the power supply for plasma generation is connected to the upper electrode, not the lower electrode. The power supply for plasma generation may also be connected to the upper electrode in addition to the lower electrode.

[0123] The power supply SC is connected to the electrode support 38 (first electrode plate 36) via a first matching box 87, a common wiring L0, and a first branch wiring L1. The power supply SC in this example is a high-frequency power supply for generating plasma, and supplies first high-frequency power from the power supply SC to the electrode support 38 and the first electrode plate 36 via the first branch wiring L1.

[0124] Furthermore, the power supply SC is connected to the second electrode plate 35 via a first matching box 87, a common wiring L0, and a second branch wiring L2. The common wiring L0 branches into a first branch wiring L1 and a second branch wiring L2, and the second branch wiring L2 is connected to the second electrode plate 35 without passing through the electrode support 38. From the power supply SC of this example, a first high frequency power is supplied to the second electrode plate 35 via the second branch wiring L2.

[0125] The power supply SF is connected to the mounting table 16 via a second matching box 8. The power supply SF in this example is a high frequency power supply for attracting ions.

[0126] The power supply SE is connected to the auxiliary electrode AXU via the sensor 83. In this example, the power supply SE is an AC power supply, but a DC power supply SD can also be used instead of the power supply SE. Either or both of the power supplies SE and SD can be connected to the auxiliary electrode AUX. The effects of using the power supply SE (SD) are as described above.

[0127] Since high-frequency power is supplied to the second electrode plate 35, a self-bias voltage, which is a negative DC voltage, is generated. Therefore, the magnitude (absolute value) of the self-bias voltage generated in the second electrode plate 35 is set to be the same as the magnitude (absolute value) of the self-bias voltage generated in the auxiliary electrode AUX. Alternatively, the magnitude (absolute value) of the self-bias voltage generated in the second electrode plate 35 may be set to be equal to or greater than the magnitude (absolute value) of the self-bias voltage generated in the auxiliary electrode AUX. This allows accelerated electrons that do not collide with particles in the plasma to be efficiently returned to the plasma.

[0128] A first variable impedance circuit 81a and / or a second variable impedance circuit 82a are provided on the first branch wiring L1 and / or the second branch wiring L2. Each variable impedance circuit may have any configuration as long as its impedance is variable. In one example, the first variable impedance circuit 81a and / or the second variable impedance circuit 82a may include a variable capacitor.

[0129] Furthermore, a sensor 83a that measures the self-bias voltage or voltage waveform generated on the second electrode plate 35 may be provided between the second electrode plate 35 and the second variable impedance circuit 82a. In this case, the self-bias voltage or voltage waveform (or the magnitude of the peak-to-peak voltage) acquired by the sensor 83a may be fed back to the control unit 95 shown in Fig. 1, and feedback control similar to that described above may be performed. The control unit 95 shown in Fig. 1 controls the power supply SC, the power supply SF, the power supply SE (SD), the first variable impedance circuit 81a, and / or the second variable impedance circuit 82a, and can set the plasma density in the peripheral region of the substrate to a target reference value.

[0130] The plasma processing apparatus of this example has a power supply SC (third power supply) that supplies a periodic signal to the second electrode plate 35. When the periodic signal is supplied to the second electrode plate 35, it is possible to improve the density of the plasma generated in the vicinity of the second electrode plate 35. In Fig. 12, the power supply SF (first power supply) that supplies a periodic signal to the mounting table 16 (first lower electrode) is a power supply for attracting ions.

[0131] The plasma processing apparatus of this example has a power transmission path (first power supply line) passing through a first branch wiring L1 and a power transmission path (second power supply line) passing through a second branch wiring L2. The first power supply line supplies a periodic signal output from a power supply SC (third power supply) to a first electrode plate 36 (first upper electrode) via an electrode support 38. The second power supply line supplies a periodic signal output from the power supply SC to a second electrode plate 35 (second upper electrode). A first variable impedance circuit 81a and a second variable impedance circuit 82a are provided on the first branch wiring L1 (first power supply line) or the second branch wiring L2 (second power supply line).

[0132] By adjusting the impedance in the first variable impedance circuit 81a and / or the second variable impedance circuit 82a, the amount of power supplied to the target upper electrode can be adjusted. Therefore, the ratio of power supplied to the first electrode plate 36 and the second electrode plate 35 can be adjusted. Plasma density depends on the amount of power supplied to the target electrode. Therefore, by adjusting the ratio of the power supplies, the in-plane uniformity of the plasma can be improved.

[0133] In this example, the power supply SA may also be connected to the mounting table 16 as in the example shown in FIGS.

[0134] As described above, the plasma processing apparatus of FIG. 12 includes a sensor 83 that measures the self-bias voltage or voltage waveform generated in the auxiliary electrode AUX and a sensor 83a that measures the self-bias voltage or voltage waveform generated in the second electrode plate 35. Feedback control based on the sensor output is possible even with only one of these sensors 83 and 83a. The control unit 95 shown in FIG. 1 controls the impedance of the first variable impedance circuit 81a and the impedance of the second variable impedance circuit 82a according to the measurement values ​​measured by the sensors 83 and 83a. These measurement values ​​are the self-bias voltage or voltage waveform (or the magnitude of the peak-to-peak voltage). Note that, as shown in FIG. 9, high-frequency power may be applied to the lower auxiliary electrode AUX from power supplies SA and SF via variable impedance circuits. In this case, the control unit 95 shown in FIG. 1 includes a sensor 83 that measures the self-bias voltage generated in the auxiliary electrode AUX (second lower electrode) and controls the impedance of the variable impedance circuits 81 and 82 shown in FIG. 9 according to the measurement value measured by the sensor 83.

[0135] The amount of power that can be transmitted varies depending on the impedance value. There is a correlation between the plasma density in the substrate peripheral region and the measurement value. If the measurement value indicates that the plasma density in the substrate peripheral region is lower than the reference value, the control unit 95 performs control to increase the plasma density. If the measurement value indicates that the plasma density in the substrate peripheral region is equal to or higher than the reference value, the control unit 95 performs control to decrease the plasma density. The reference value and the correlation between the measurement value and the plasma density can also be stored in advance in the memory unit 97 of FIG. 1.

[0136] The method for increasing the plasma density in the substrate peripheral region is as described above. The impedance of the variable impedance circuit controls the plasma density generated in the space above the substrate mounting region (the space between the mounting table 16 and the first electrode plate 36) and the space above the substrate peripheral region (the space between the auxiliary electrode AUX and the second electrode plate 35). The measurement value obtained by the sensor correlates with the plasma density in the substrate peripheral region. Therefore, the control unit 95 can adjust the amount of power supplied to the electrodes connected to the variable impedance circuits 81a and 82a by adjusting the impedance of the variable impedance circuits 81a and 82a according to the plasma density corresponding to the measurement value. The plasma density depends on the amount of power supplied to the target electrode. Therefore, the in-plane uniformity of the plasma can be improved by adjusting the ratio of the power supply amounts based on the measurement values ​​obtained by the sensors 83 and 83a.

[0137] 13 is a diagram showing a vertical cross-sectional configuration of a substrate and its surroundings in a plasma processing apparatus according to an exemplary embodiment. This example is different from the plasma processing apparatus shown in FIG. 12 only in the power supply connection relationship on the upper side, and the other configurations are the same.

[0138] The power supply SC is connected to the electrode support 38 (first electrode plate 36) via a first matching box 87. The power supply SB is connected to the second electrode plate 35 via a sensor 83a. The power supply SC is a high-frequency power supply for generating plasma shown in FIG. 12. The upper power supply SB can have the same configuration as the lower power supply SE (SD). In other words, the power supply SB is a DC power supply that generates a DC voltage, but it may also be a pulse power supply or a high-frequency power supply. In addition to the power supply SB (DC voltage), another power supply (pulse power supply, high-frequency power supply) may be connected to the second electrode plate 35.

[0139] In either case, as shown in FIG. 3, the average (or effective) value of the potential of the second electrode plate 35 is equal to or greater than the average (or effective) value of the potential of the auxiliary electrode AUX (Condition 1) is satisfied. The outputs of the power supplies SB and SE (SD) are set to satisfy Condition 1. To satisfy Condition 1, the outputs of the power supplies SC and SF may be controlled in addition to the outputs of the power supplies SB and SE (SD). That is, to satisfy Condition 1, the outputs of at least one of the power supplies SB, SE (SD), SC, and SF may be controlled. When the power supply is a high-frequency power supply (AC power supply), the variable impedance circuits described above may be provided between the power supply and the electrode. The impedances of these variable impedance circuits may be controlled to satisfy Condition 1. These controls may also be performed based on the values ​​of the self-bias voltage or voltage waveform (or the magnitude of the peak-to-peak voltage) generated at the second electrode plate 35 and / or the auxiliary electrode AUX obtained from the sensors 83 and 83a. The feedback control method is the same as the control described above.

[0140] This allows accelerated electrons that do not collide with particles in the plasma to be efficiently returned to the plasma, enabling efficient plasma generation even around the substrate where the plasma density is low, thereby improving plasma uniformity.

[0141] The second electrode plate 35 and the auxiliary electrode AUX need only face each other at the periphery of the substrate, and do not have to be arranged parallel to the substrate placement area. In addition, the second electrode plate 35 and the auxiliary electrode AUX do not have to be connected to a DC power supply or a high-frequency power supply.

[0142] FIG. 14 is a diagram showing a vertical cross-sectional configuration of the periphery of a substrate in a plasma processing apparatus.

[0143] As shown in the figure, the insulating member 26 has an inclined surface, and the auxiliary electrode AUX is placed on the inclined surface. The auxiliary electrode AUX is electrically connected to the chamber 10 via wiring and is grounded. The shape of the auxiliary electrode AUX is shown as the same as that shown in Figure 6, but the shape is not limited to this. The shape of the recess D can also be the shape shown in Figure 7, or the recess D may be omitted and the electrode may be flat. A second electrode plate 35b having a flat surface inclined from the horizontal direction is provided facing the auxiliary electrode AUX. That is, the second electrode plate 35b is positioned on the normal to the surface of the recess D of the auxiliary electrode AUX. The second electrode plate 35b is grounded via the sidewall of the chamber 10. The second electrode plate 35b may be formed by the sidewall of the chamber 10 or by a deposit shield. Furthermore, the recess D may be formed on the second electrode plate 35b rather than on the auxiliary electrode AUX side, as in the second electrode plate 35 shown in Figure 4 or Figure 5. The recesses D may be provided in both the auxiliary electrode AUX and the second electrode plate 35b.

[0144] 14, the insulating member 39 shown in FIG. 13 does not exist, and the horizontal end of the first electrode plate 36 abuts against the inner peripheral surface of the insulating shielding member 42. The first electrode plate 36 and the second electrode plate 35b are electrically separated by the insulating shielding member 42.

[0145] In the plasma processing apparatus of this embodiment, the auxiliary electrode AUX having the recess D is placed on an inclined surface, and the second electrode plate 35b faces the recess D with a flat surface inclined from the horizontal direction. That is, the auxiliary electrode AUX is disposed so that the normal to the bottom surface of the recess D is inclined with respect to the normal to the substrate placement region.

[0146] In the plasma processing apparatus of this embodiment, the second electrode plate 35b and the auxiliary electrode AUX are grounded and have the same potential. The plasma PL generated between the mounting table 16 and the first electrode plate 36 diffuses into the space between the auxiliary electrode AUX and the second electrode plate 35b. The strength of the sheath electric field is proportional to the difference between the plasma potential and the wall potential. Furthermore, the plasma potential increases with increasing bias power and is maximized when the bias power is positive. This creates a large potential gradient between the potential of the grounded auxiliary electrode AUX and the plasma. When the sheath is thin, electrons present in the plasma near the auxiliary electrode AUX are accelerated toward the second electrode plate 35b (toward the plasma) facing the auxiliary electrode AUX. Some of the accelerated electrons collide with particles in the plasma, contributing to an increase in plasma density. Meanwhile, the remaining accelerated electrons that do not collide with particles in the plasma are subjected to a repulsive force by the sheath electric field between the second electrode plate 35b and the plasma and are returned to the plasma. Similarly, electrons present in the plasma near the second electrode plate 35b when the sheath is thin are accelerated toward the plasma and are subjected to a repulsive force by the sheath electric field between the auxiliary electrode AUX and the plasma, returning to the plasma. Therefore, accelerated electrons travel back and forth in the space between the second electrode plate 35b and the auxiliary electrode AUX, improving the plasma density around the substrate. This improves the uniformity of the plasma.

[0147] Alternatively, a high frequency power supply and / or a DC power supply may be electrically connected to the auxiliary electrode AUX and the second electrode plate 35b to apply a potential to the auxiliary electrode AUX and the second electrode plate 35b.

[0148] FIG. 15 is a diagram showing an example of the positional relationship between the auxiliary electrode AUX and the second electrode plate 35b.

[0149] Both the auxiliary electrode AUX and the second electrode plate 35b have a recess D. A plurality of normals (NAUX, NAUXa) can be set to the surface of the recess D in the auxiliary electrode AUX. The normal NAUX extends toward the deepest part of the recess D in the second electrode plate 35b. The normal NAUX at the deepest part of the recess D of the auxiliary electrode AUX is inclined with respect to the vertical direction (Z-axis direction).

[0150] A plurality of normals (N35, N35a) can also be set to the surface of the recess D in the second electrode plate 35b. The normal N35 is a normal to the deepest part of the recess D in the second electrode plate 35. The normal N35 extends toward the deepest part of the recess D in the auxiliary electrode AUX. The normal N35 to the deepest part of the recess D in the second electrode plate 35b is also inclined with respect to the vertical direction (Z-axis direction). Except for the inclination, the shape of each recess D is the same as that described in FIG. 8.

[0151] A normal N18 to the surface of the substrate mounting area on the electrostatic chuck 18 is parallel to the vertical direction (Z-axis direction). The second electrode plate 35b and the auxiliary electrode AUX are arranged so that the normal NAUX (or N35) to the bottom surface of the recess D is inclined at an angle θ with respect to the normal N18 to the substrate mounting area. By changing the distance between the second electrode plate 35b and the auxiliary electrode AUX and the inclination angle θ, the intensity and shape of the plasma in the area surrounding the substrate can be changed. This improves the design freedom of the in-plane distribution of plasma density, thereby improving the in-plane uniformity of the plasma.

[0152] Electrons near the surface of the recessed portion D of the auxiliary electrode AUX are accelerated in the XZ plane toward the recessed portion D of the second electrode plate 35b. The accelerated electrons are focused toward the second electrode plate 35b. Conversely, electrons near the surface of the recessed portion D of the second electrode plate 35b are accelerated in the XZ plane toward the recessed portion D of the auxiliary electrode AUX. These accelerated electrons are focused toward the auxiliary electrode AUX. This increases the plasma density in the peripheral region of the substrate. This makes it possible to suppress an increase in plasma density in the central portion of the substrate mounting region. This makes it possible to improve the in-plane uniformity of the plasma.

[0153] The second electrode plate 35b may be configured as an inner wall of the chamber 10 (processing vessel) or a deposit shield provided along the inner wall of the chamber 10. The inner wall surface of the chamber 10 shown in FIG. 1 corresponds to these elements. In this case, the second electrode plate 35b also serves as the inner wall of the chamber or the deposit shield, thereby achieving the above-described effects and reducing the number of parts. The structures of FIGS. 14 and 15 can also be applied to other embodiments.

[0154] 16 is a diagram showing the connection relationship between the power supply and the electrodes. The electrodes and the power supply described above can be electrically connected in various ways.

[0155] For example, in the above-described embodiment, the second electrode plate 35 (35b) and the auxiliary electrode AUX may be electrically grounded. In this case, the auxiliary electrode AUX is connected to a ground potential G1, and the second electrode plate 35 is connected to a ground potential G2. When a plasma sheath with a positive potential is formed between the auxiliary electrode AUX and the second electrode plate 35, electrons near these electrodes travel toward the sheath. The electrons that move toward the sheath contribute to plasma generation, increasing the plasma density in the region surrounding the substrate. This improves the in-plane uniformity of the plasma.

[0156] The electrode group below the plasma generation region includes a mounting table 16 and an auxiliary electrode AUX. These electrode groups include a power supply circuit group S for the lower electrode group.DOWN Power supply circuit group S DOWN includes a first power supply SA, a power supply SF for attracting ions, a fourth power supply SD, a fifth power supply SE, a ground potential G1, and a distribution circuit DIV1 for distributing power.

[0157] The electrode group above the plasma generation region includes a first electrode plate 36 and a second electrode plate 35. These electrode groups include a power supply circuit group S for the upper electrode group. UP Power supply circuit group S UP includes a third power supply SC, a second power supply SB, a ground potential G2, and a distribution circuit DIV2 that distributes power.

[0158] As shown in Figure 9, the configuration of the lower distribution circuit DIV1 is a circuit that includes a variable impedance circuit in the power transmission path, and changes the power supply ratio to the connected electrodes depending on the value of these impedances.

[0159] Power can be supplied to the mounting table 16 and auxiliary electrode AUX from the lower power supply via the distribution circuit DIV1. Power can also be supplied to the mounting table 16 and auxiliary electrode AUX from the lower power supply without via the distribution circuit DIV1. The first power supply SA is a high-frequency power supply, and the power supply SF for ion attraction is a power supply with a lower frequency than the first power supply SA. The fourth power supply SD is a DC power supply, and the fifth power supply SE is a high-frequency power supply. There are multiple combinations of these power supplies.

[0160] The power supply SF for ion attraction is connected to the mounting table 16 with or without a distribution circuit DIV1. The power supply for plasma generation is designated as a first power supply SA. The first power supply SA can be connected to the mounting table 16 with or without a distribution circuit DIV1. Any one of the fourth power supply SD, the fifth power supply SE, and the ground potential G1 can be connected to the auxiliary electrode AUX. Both the fourth power supply SD and the fifth power supply SE can be connected to the auxiliary electrode AUX without the distribution circuit DIV1. A sensor for measuring the self-bias voltage or voltage waveform of the auxiliary electrode AUX can be provided in the connected path. The outputs of the first power supply SA, the fourth power supply SD, and the fifth power supply SE may be connected to the mounting table 16 and the auxiliary electrode AUX via the distribution circuit DIV1. A sensor for measuring the self-bias voltage or voltage waveform can be provided in any of the power transmission paths, and control may be performed based on the feedback method described above to improve the in-plane plasma uniformity.

[0161] As shown in FIG. 12, the upper distribution circuit DIV2 is configured as a circuit that includes a variable impedance circuit in the power transmission path, and changes the power supply ratio to the connected electrodes according to the ratio of these impedances.

[0162] Power can be supplied from the upper power supply to the first electrode plate 36 and the second electrode plate 35 via the distribution circuit DIV2. Power can also be supplied from the upper power supply to the first electrode plate 36 and the second electrode plate 35 without via the distribution circuit DIV2. The third power supply SC is a high-frequency power supply. The second power supply SB is a DC power supply, but can also be a pulse power supply or a high-frequency power supply. The second power supply SB may be equipped with a DC power supply and a high-frequency power supply (a power supply that supplies a periodic signal), and may be configured to apply a DC voltage and an AC voltage (high-frequency voltage) to the second electrode plate 35 from each.

[0163] If the power source for generating plasma is a third power source SC, the third power source SC can be connected to the first electrode plate 36 with or without a distribution circuit DIV2. Any one of the third power source SC, the second power source SB, and the ground potential G2 can be connected to the second electrode plate 35. Both the third power source SC and the second power source SB can be connected to the second electrode plate 35 without the distribution circuit DIV2. A sensor for measuring the self-bias voltage or voltage waveform of the second electrode plate 35 can be provided in the connected path. The outputs of the third power source SC and the second power source SB may be connected to the first electrode plate 36 and the second electrode plate 35 via the distribution circuit DIV2. A sensor for measuring the self-bias voltage or voltage waveform can be provided in any of the power transmission paths, and control may be performed based on the feedback method described above to improve the in-plane uniformity of the plasma. Feedback control that improves the in-plane uniformity of the plasma can be applied to all embodiments. Feedforward control may be used instead of feedback control.

[0164] Also, the lower power supply circuit group S DOWN When one of the above power supplies connected to the auxiliary electrode AUX is selected, the upper power supply circuit group S UPAny of the power supplies described above connected to the second electrode plate 35 can be selected and combined. For example, power supply SD can be selected as the lower power supply that applies a DC voltage, and power supply SB can be selected as the upper power supply that applies a DC voltage. Alternatively, power supply SD can be selected as the lower power supply that applies a DC voltage, and power supply SB can be selected as the upper power supply that applies an AC voltage (a periodic signal). In this case, power supply SB can include a power supply that applies a DC voltage and a power supply that applies an AC voltage. If power supply SB includes an AC power supply, it can be connected in the same manner as power supply SC shown in FIG. 12 and can include a variable impedance circuit in the power transmission path. In any of the combinations, the output from the first power supply SA can be branched, as shown in FIG. 9, and a variable impedance circuit and a sensor for measuring the self-bias voltage or voltage waveform can be provided. A fifth power supply SE can be connected to the auxiliary electrode AUX alone or in combination with any of the power supply connections described above.

[0165] As described above, the plasma processing apparatus includes a chamber 10, a mounting table 16, an electrostatic chuck 18 (first lower electrode), and an auxiliary electrode AUX (second lower electrode). The plasma processing apparatus further includes a first electrode plate 36 (first upper electrode), second electrode plates 35, 35b (second upper electrode), and a first power supply SA (SF). The mounting table 16 and the electrostatic chuck 18 are provided inside the chamber 10 and have a substrate mounting area on which a semiconductor wafer W is mounted. The auxiliary electrode AUX is disposed in a substrate peripheral area. The first electrode plate 36 is disposed opposite the substrate mounting area. The second electrode plates 35, 35b are disposed in an area outside the first electrode plate 36 and opposite the auxiliary electrode AUX. The first power supply SA (SF) supplies a periodic signal to the mounting table 16. At least one of the auxiliary electrode AUX and the second electrode plates 35, 35b has a recess D. The auxiliary electrode AUX or the second electrode plate 35, 35b is located on the normal to the surface of the recess D.

[0166] Since electrons accelerated from the vicinity of the surface of the recess D of one of the auxiliary electrode AUX and the second electrode plate 35, 35b toward the other are converged, the plasma density increases in the peripheral region of the substrate, and it is possible to prevent the plasma density from becoming too high in the center of the substrate mounting region, thereby improving the in-plane uniformity of the plasma.

[0167] In addition, the structure in which only the lower surface of the second electrode plate 35 has the recess D, the structure in which only the upper surface of the auxiliary electrode AUX has the recess D, or the structure in which both of these have recesses can be applied to all embodiments. In the above description, the edge ring ER and the auxiliary electrode AUX may be integrated.

[0168] Although various exemplary embodiments have been described above, various omissions, substitutions, and modifications may be made without being limited to the above-described exemplary embodiments. Furthermore, elements from different embodiments may be combined to form other embodiments. It will be understood from the above description that various embodiments of the present disclosure have been described herein for illustrative purposes, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0169] 1...plasma processing apparatus, 10...chamber, 10a...ground conductor, 14...support table, 16...mounting table (first lower electrode), 18...electrostatic chuck, 26...insulating member, 34...upper electrode, 35, 35b...second electrode plate (second upper electrode), 36...first electrode plate (first upper electrode), 37...discharge hole, 38...electrode support, 39...insulating member, 40...gas diffusion chamber, 41...gas flow hole, 42...insulating shielding member, 62...gas inlet, 64...gas supply pipe, 66...processing gas supply Source, 70...valve, 81, 81a, 82, 82a...variable impedance circuit, 83, 83a...sensor, 84...exhaust device, 85...opening, 86...gate valve, 87...first matching box, 88...second matching box, SA...power supply, SB...power supply, SC...power supply, SD...power supply, SE...power supply, 95...control unit, 96...user interface, 97...memory unit, AUX...auxiliary electrode (second lower electrode), ER...edge ring, PL...plasma, W...semiconductor wafer, D...recess.

Claims

1. a chamber; a first lower electrode provided inside the chamber and having a substrate placement area on which a substrate is placed; a second lower electrode disposed in an area outside the substrate mounting area; a first upper electrode disposed opposite the substrate placement area; a second upper electrode disposed in an outer region of the first upper electrode and facing the second lower electrode; a first power supply that supplies a periodic signal to the first lower electrode; and At least one of the second lower electrode and the second upper electrode has a flat portion, a second power supply that supplies a periodic signal to the second upper electrode; a first power supply line that supplies the periodic signal output from the second power supply to the first upper electrode; a second power supply line that supplies the periodic signal output from the second power supply to the second upper electrode; and a variable impedance circuit is provided on the first power supply line or the second power supply line; A plasma processing apparatus further comprising a sensor for measuring a self-bias voltage or a voltage waveform generated in the second lower electrode or the second upper electrode, and a control unit for controlling the impedance of the variable impedance circuit in accordance with the measurement value measured by the sensor.

2. a chamber; a first lower electrode provided inside the chamber and having a substrate placement area on which a substrate is placed; a second lower electrode disposed in an area outside the substrate mounting area; a first upper electrode disposed opposite the substrate placement area; a second upper electrode disposed in an outer region of the first upper electrode and facing the second lower electrode; a first power supply that supplies a periodic signal to the first lower electrode; and At least one of the second lower electrode and the second upper electrode has a flat portion, a first power supply line that supplies the periodic signal output from the first power supply to the first lower electrode; a second power supply line that supplies the periodic signal output from the first power supply to the second lower electrode; and a variable impedance circuit is provided on the first power supply line or the second power supply line; A plasma processing apparatus further comprising a sensor for measuring a self-bias voltage or a voltage waveform generated in the second lower electrode or the second upper electrode, and a control unit for controlling the impedance of the variable impedance circuit in accordance with the measurement value measured by the sensor.

3. a chamber; a first lower electrode provided inside the chamber and having a substrate placement area on which a substrate is placed; a second lower electrode disposed in an area outside the substrate mounting area; a first upper electrode disposed opposite the substrate placement area; a second upper electrode disposed in an outer region of the first upper electrode and facing the second lower electrode; a first power supply that supplies a periodic signal to the first lower electrode; and At least one of the second lower electrode and the second upper electrode has a flat portion, a second power supply that supplies a periodic signal to the second lower electrode; A plasma processing apparatus further comprising a sensor for measuring a self-bias voltage or a voltage waveform generated in the second lower electrode, and a control unit for controlling the output of the second power supply in accordance with the measurement value measured by the sensor.

4. 4. The plasma processing apparatus according to claim 1, further comprising a power supply that supplies a DC voltage to the second upper electrode.

5. a chamber; a first lower electrode provided inside the chamber and having a substrate placement area on which a substrate is placed; a second lower electrode disposed in an area outside the substrate mounting area; a first upper electrode disposed opposite the substrate placement area; a second upper electrode disposed in an outer region of the first upper electrode and facing the second lower electrode; a first power supply that supplies a periodic signal to the first lower electrode; and At least one of the second lower electrode and the second upper electrode has a flat portion, a second power supply that supplies a DC voltage to the second upper electrode; A plasma processing apparatus further comprising a sensor for measuring a self-bias voltage or a voltage waveform generated in the second lower electrode, and a control unit for controlling the output of the second power supply in accordance with the measurement value measured by the sensor.

6. 6. The plasma processing apparatus according to claim 5, wherein the control unit controls the output of the second power supply so that a negative DC voltage greater than or equal to the self-bias voltage generated in the second lower electrode is generated in the second upper electrode.

7. 7. The plasma processing apparatus according to claim 5, further comprising a third power supply that supplies a periodic signal to the second upper electrode.

8. both the second lower electrode and the second upper electrode have the flat portion; The plasma processing apparatus according to any one of claims 1 to 6.

9. a first power supply line that supplies the periodic signal output from the third power supply to the first upper electrode; a second power supply line that supplies the periodic signal output from the third power supply to the second upper electrode; and 8. The plasma processing apparatus according to claim 7, further comprising a variable impedance circuit in the first power supply line or the second power supply line.

10. 10. The plasma processing apparatus according to claim 1, wherein the distance between the second upper electrode and the second lower electrode is narrower than the distance between the first upper electrode and the first lower electrode.

11. 11. The plasma processing apparatus according to claim 1, further comprising a conductive edge ring between the second lower electrode and the substrate placement area on which the substrate is placed.

12. A plasma processing apparatus described in any one of claims 1 to 11, wherein the second upper electrode has the flat portion, and the second upper electrode is positioned so that the normal to the flat portion of the second upper electrode is inclined with respect to the normal to the substrate mounting area.

13. 13. The plasma processing apparatus according to claim 12, wherein the second upper electrode is configured by a deposit shield provided on an inner wall of the chamber or along the inner wall of the chamber.

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