Plasma processing apparatus

Abstract

The present application provides a kind of plasma processing device, can improve the in-plane uniformity of plasma.Plasma processing device has chamber, first lower electrode, second lower electrode, first upper electrode, second upper electrode and first power supply.First lower electrode is arranged in the inside of chamber, and the first lower electrode has substrate placement area for placing substrate.Second lower electrode is configured in the area outside substrate placement area.First upper electrode is configured opposite substrate placement area.Second upper electrode is configured in the area outside first upper electrode, and is configured opposite second lower electrode.At least one of first lower electrode and second lower electrode has recess.Second lower electrode or second upper electrode is located on the normal line of the surface of recess.

Description

Technical Field

[0001] The exemplary embodiments of this disclosure relate to a plasma processing apparatus. Background Technology

[0002] In the plasma processing apparatus disclosed in Patent Document 1 or Patent Document 2, a stepped ramp is provided around the upper electrode to increase the plasma density in the surrounding area.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Publication No. 2004-511906

[0006] Patent Document 2: Japanese Patent Application Publication No. 2009-239014 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] According to the aforementioned literature, by providing a stepped ramp around the periphery of the upper electrode, electrons can be concentrated near the ramp angle, thus enabling efficient plasma generation. On the other hand, there is a need for a plasma processing device that can improve the in-plane uniformity of the plasma.

[0009] Solution for solving the problem

[0010] 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 disposed inside the chamber and has a substrate mounting region for mounting a substrate. The second lower electrode is disposed in a region outside the substrate mounting region. The first upper electrode is disposed facing the substrate mounting region. The second upper electrode is disposed in a region outside the first upper electrode and facing 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.

[0011] The effects of the invention

[0012] According to the plasma processing device, the in-plane uniformity of the plasma can be improved. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating the basic structure of a plasma processing apparatus according to an exemplary embodiment.

[0014] Figure 2 This is a longitudinal cross-sectional view showing the basic structure of the main parts of the plasma processing apparatus involved in the exemplary embodiment.

[0015] Figure 3 It is a graph showing the relationship between position Z in the vertical direction and potential V(au).

[0016] Figure 4 This is a diagram showing the longitudinal cross-sectional structure of the main parts of the plasma processing apparatus involved in an exemplary embodiment.

[0017] Figure 5 This is a diagram showing the longitudinal cross-sectional structure of the main parts of the plasma processing apparatus involved in the illustrated embodiment.

[0018] Figure 6 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in the plasma processing apparatus according to the illustrated embodiment.

[0019] Figure 7 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in a plasma processing apparatus according to an exemplary embodiment.

[0020] Figure 8 This is a diagram illustrating an example of the positional relationship between the auxiliary electrode and the second electrode plate.

[0021] Figure 9 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in a plasma processing apparatus according to an exemplary embodiment.

[0022] Figure 10 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in a plasma processing apparatus according to an exemplary embodiment.

[0023] Figure 11 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in a plasma processing apparatus according to an exemplary embodiment.

[0024] Figure 12 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in a plasma processing apparatus according to an exemplary embodiment.

[0025] Figure 13 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in a plasma processing apparatus according to an exemplary embodiment.

[0026] Figure 14 This is a diagram showing the longitudinal cross-sectional structure of the main parts of the plasma processing apparatus involved in an exemplary embodiment.

[0027] Figure 15This is a diagram illustrating an example of the positional relationship between the auxiliary electrode and the second electrode plate.

[0028] Figure 16 It is a diagram showing the connection relationship between the power source and the electrodes. Detailed Implementation

[0029] The following describes various exemplary implementation methods.

[0030] 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 disposed inside the chamber and has a substrate mounting region for mounting a substrate. The second lower electrode is disposed in a region outside the substrate mounting region (hereinafter referred to as a substrate peripheral region). The first upper electrode is disposed facing the substrate mounting region. The second upper electrode is disposed in a region outside the first upper electrode and is disposed facing 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.

[0031] At least one of the second lower electrode and the second upper electrode has a recess. Electrons accelerated from near the surface of the recess on one side toward the other are concentrated, thereby increasing the plasma density in the peripheral region of the substrate and suppressing the increase in plasma density in the center of the substrate mounting region. As a result, the in-plane uniformity of the plasma can be improved.

[0032] In one exemplary embodiment, both the second lower electrode and the second upper electrode may have recesses. Alternatively, the recess of the second upper electrode may be located on the normal to the surface of the recess of the second lower electrode, and the recess of the second lower electrode may also be located on the normal to the surface of the recess of the second upper electrode. Electrons accelerated from the vicinity of the recess of one of the second lower and upper electrodes toward the recess of the other are concentrated. Conversely, electrons accelerated from the vicinity of the recess of the other electrode toward the recess of one electrode are also concentrated. Therefore, the plasma density in the peripheral region of the substrate increases. This suppresses the increase in plasma density at the center of the substrate mounting region. Consequently, the in-plane uniformity of the plasma can be improved.

[0033] 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. When a DC voltage is supplied to the second upper electrode, a force can be applied to electrons moving toward the second upper electrode, thereby controlling the plasma density near the second upper electrode. When a repulsive force is applied to these electrons, they move away from the second upper electrode, increasing the plasma density in the peripheral region of the substrate. This allows adjustment of the ratio of the plasma density at the center of the substrate mounting area to the plasma density in the peripheral region of the substrate. Consequently, the in-plane uniformity of the plasma can be improved.

[0034] In one exemplary embodiment, the plasma processing apparatus may further include a third power source that supplies a periodic signal to the second upper electrode. When a periodic signal is supplied to the second upper electrode, the density of the plasma generated near the second upper electrode can be increased. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0035] In one exemplary embodiment, the plasma processing apparatus may have a first power supply line and a second power supply line. The first power supply line is used to supply a periodic signal output from a third power source to a first upper electrode. The second power supply line is used to supply a periodic signal output from the third power source to a second upper electrode. A variable impedance circuit may be included in either the first or second power supply line.

[0036] By adjusting the impedance of the variable impedance circuit, the amount of power supplied to the upper electrode can be adjusted. Therefore, the ratio of power supplied to the first and second upper electrodes can be adjusted. The plasma density depends on the amount of power supplied to the electrodes. Therefore, by adjusting the ratio of the power supply, the in-plane uniformity of the plasma can be improved.

[0037] In one exemplary embodiment, the plasma processing apparatus may further include a fourth power source that supplies a DC voltage to the second lower electrode. When a DC voltage is supplied to the second lower electrode, a force can be applied to electrons moving toward the second lower electrode, thereby controlling the plasma density near the second lower electrode. When a repulsive force is applied to the electrons, the electrons move away from the second lower electrode, increasing the plasma density in the region surrounding the substrate. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0038] In one exemplary embodiment, the plasma processing apparatus may further include a third power supply line and a fourth power supply line. The third power supply line is used to supply a periodic signal output from the first power supply to the first lower electrode. The fourth power supply line is used to supply a periodic signal output from the first power supply to the second lower electrode. In the plasma processing apparatus, the third or fourth power supply line may also include a variable impedance circuit.

[0039] By adjusting the impedance of the variable impedance circuit, the amount of power supplied to the lower electrode can be adjusted. Therefore, the ratio of power supplied to the first and second lower electrodes can be adjusted. The plasma density depends on the amount of power supplied to the electrodes. Therefore, by adjusting the ratio of the power supply, the in-plane uniformity of the plasma can be improved.

[0040] In one exemplary embodiment, the plasma processing apparatus may further include a fifth power source that supplies a periodic signal to the second lower electrode. When a periodic signal is supplied to the second lower electrode, the density of the plasma generated near the second lower electrode can be increased. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0041] In one exemplary embodiment, the plasma processing apparatus may also include a sensor that measures the self-bias voltage or voltage waveform generated at 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 based on the measured values ​​obtained from the sensor.

[0042] The impedance control of the variable impedance circuit controls the plasma density generated in the space on the substrate mounting area (the space between the first lower electrode and the first upper electrode) and the space on the substrate periphery (the space between the second lower electrode and the second upper electrode). The measured value obtained by the sensor is related to the plasma density in the substrate periphery region. Therefore, by adjusting the impedance of the variable impedance circuit according to the plasma density corresponding to the measured value, the power supply to the electrode connected to the variable impedance circuit can be adjusted. The plasma density depends on the power supply to the electrode being targeted. Therefore, by adjusting the ratio of the power supply based on the sensor's measurement value, the in-plane uniformity of the plasma can be improved.

[0043] In one exemplary embodiment, the plasma processing apparatus may also include a sensor that measures the self-bias voltage or voltage waveform generated at the second lower electrode. The plasma processing apparatus may also include a control unit that controls the output of the second power supply based on the measured values ​​from the sensor.

[0044] The measured value obtained by the sensor is related to the amount of electrons reflected from the second lower electrode, i.e., the plasma density in the region surrounding the substrate. Furthermore, the plasma density can be adjusted by changing the output of the second power supply. Therefore, by adjusting the output of the second power supply according to the plasma density corresponding to the measured value, the plasma density in the region surrounding the substrate can be controlled. This improves the in-plane uniformity of the plasma.

[0045] In one exemplary embodiment, the plasma processing apparatus may also include a sensor that measures the self-bias voltage or voltage waveform generated at the second lower electrode. The plasma processing apparatus may also include a control unit that controls the output of the fifth power supply based on the measurements taken by the sensor.

[0046] The measured value obtained by the sensor is related to the amount of electrons reflected from the second lower electrode, i.e., the plasma density in the region surrounding the substrate. When the control unit adjusts the output of the fifth power supply according to the plasma density corresponding to the measured value, the plasma density in the region surrounding the substrate can be controlled. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0047] In one exemplary embodiment, the control unit may control the output of the second power supply to generate a negative DC voltage at the second upper electrode that is greater than or equal to the self-bias voltage generated by the second lower electrode.

[0048] When a negative DC voltage is applied to the second upper electrode, a repulsive force is exerted on electrons heading towards the second upper electrode, causing the electrons to be reflected. The reflected electrons travel towards the plasma region, contributing to plasma generation, thus increasing the plasma density in the region surrounding the substrate. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0049] In one exemplary embodiment, the second lower electrode and the second upper electrode may also be electrically grounded. If 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 the generation of plasma, thus increasing the plasma density in the region surrounding the substrate. Therefore, as described above, the in-plane uniformity of the plasma can be improved.

[0050] In one exemplary embodiment, the spacing between the second upper electrode and the second lower electrode may be narrower than the spacing between the first upper electrode and the first lower electrode. This strengthens the electric field in the peripheral region of the substrate (the region between the second upper electrode and the second lower electrode), thereby increasing the plasma density in that region. Consequently, as described above, the in-plane uniformity of the plasma can be improved.

[0051] In one exemplary embodiment, the plasma processing apparatus may have a conductive edge ring between the substrate mounting region for mounting the substrate and the second lower electrode. The edge ring can adjust the electric field at the periphery of the substrate mounting region. Therefore, the uniformity of the plasma processing can be improved.

[0052] In one exemplary embodiment, the second upper electrode and the second lower electrode may be arranged such that the normal to the bottom surface of the recess is inclined relative 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 aforementioned inclination angle, the intensity and shape of the plasma in the substrate peripheral region can be changed. The design freedom of the in-plane distribution of plasma density is increased, thereby improving the in-plane uniformity of the plasma.

[0053] In one exemplary embodiment, the second upper electrode may also be formed by the inner wall of the chamber or a deposit shield disposed along the inner wall of the chamber. In this case, the second upper electrode serves as both the inner wall of the chamber and the deposit shield, thus reducing the number of components while achieving the aforementioned effects.

[0054] The following description, with reference to the accompanying drawings, details various exemplary embodiments. Furthermore, in the drawings, identical or equivalent parts are labeled with the same reference numerals, and repeated descriptions are omitted.

[0055] Figure 1 This diagram illustrates the basic structure of a plasma processing apparatus 1 according to an exemplary embodiment. The plasma processing apparatus 1 of this embodiment is, for example, a capacitively coupled parallel-plate plasma etching apparatus. The plasma processing apparatus 1 has, for example, a generally cylindrical chamber 10 formed of aluminum with an anodized surface. The chamber 10 is safely grounded.

[0056] At the bottom of chamber 10, a cylindrical support platform 14 is disposed with respect to an insulating plate made of ceramic or the like. A mounting platform 16 made of, for example, aluminum is provided on the support platform 14. The mounting platform 16 functions as a lower electrode (first lower electrode).

[0057] The stage 16 has a substrate mounting area for mounting a substrate. An electrostatic chuck 18 is provided on the upper surface of the stage 16 to attract and hold a semiconductor wafer W, an example of a substrate, using electrostatic force. The electrostatic chuck 18 has a structure in which electrodes 20 formed of a conductive film are sandwiched between a pair of insulating layers or insulating plates. The electrodes 20 are electrically connected to a DC power supply SG. The semiconductor wafer W is placed on the upper surface of the electrostatic chuck 18, and is attracted and held in the electrostatic chuck 18 by the electrostatic force generated by the DC voltage supplied from the DC power supply SG. The upper surface of the electrostatic chuck 18 for mounting the semiconductor wafer W is an example of the substrate mounting area of ​​the stage 16.

[0058] An edge ring ER is provided on the upper surface of the mounting stage 16. The edge ring ER is provided in a manner that surrounds the substrate mounting area. The edge ring ER has a ring shape and is arranged such that the vertical central axis of the electrostatic chuck 18 is aligned with the vertical central axis of the edge ring ER. The edge ring ER is formed of a material with equal conductivity. The edge ring ER can be disposed on the electrostatic chuck 18. When viewed from above, the edge ring ER is disposed between the substrate mounting area and the auxiliary electrode AUX. The edge ring ER can adjust the electric field so that the active species travel in the vertical direction (the direction perpendicular to the substrate surface) at the periphery of the substrate mounting area. The edge ring ER improves the uniformity of plasma processing such as etching. An insulating member 26, for example formed of quartz, is provided on the side of the mounting stage 16 and the support stage 14. The insulating member 26 includes a cylindrical inner wall member. The insulating member 26 can be composed of multiple components, and conductive wiring can be arranged inside the insulating member 26.

[0059] The auxiliary electrode AUX is an annular component disposed on the outer periphery of the edge ring ER, arranged such 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 and the edge ring ER are arranged concentrically, and the auxiliary electrode AUX is disposed in the region outside the substrate mounting area (substrate periphery region). The auxiliary electrode AUX is formed of a conductive material such as silicon and is mounted on the insulating member 26.

[0060] An annular refrigerant chamber is formed inside the mounting stage 16. Cooling water or other refrigerant at a specified temperature is circulated into this chamber from an external cooling device via piping. The temperature of the mounting stage 16 and the electrostatic chuck 18 is controlled by the refrigerant circulating within the chamber, thereby maintaining the semiconductor wafer W on the electrostatic chuck 18 at a specified temperature.

[0061] Additionally, heat transfer gases such as He gas from a heat transfer gas supply mechanism (not shown) are supplied via piping inside the stage 16 to the space between the upper surface of the electrostatic chuck 18 and the back surface of the semiconductor wafer W.

[0062] Above the mounting stage 16, which functions as the lower electrode, an upper electrode 34 is disposed facing the mounting stage 16. The space between the upper electrode 34 and the mounting stage 16 is a plasma generation space, in which plasma PL is generated.

[0063] 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 can be a cylindrical insulating member with supporting steps provided on its inner surface. The upper electrode 34 has 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 facing surface opposite to the mounting stage 16, and the first electrode plate 36 has a plurality of ejection holes 37. Preferably, the first electrode plate 36 and the second electrode plate 35 are formed of a low-resistance conductor or semiconductor with low Joule heating, for example preferably silicon or SiC. The second electrode plate 35 has an annular shape and is concentrically arranged around the first electrode plate 36 in a manner surrounding the first electrode plate 36. The first electrode plate 36 is positioned above the edge ring ER and the electrostatic chuck 18. The second electrode plate 35 is positioned above the auxiliary electrode AUX. The second electrode plate 35 is insulated from the first electrode plate 36 by an insulating member 39. Furthermore, the insulating member 39 can be made thinner to allow high-frequency current to flow through it when high-frequency power is applied to the upper electrode 34. The first electrode plate 36 and the second electrode plate 35 shown in the figure are examples and can be modified in various ways.

[0064] The electrode support 38 supports the first electrode plate 36 and the second electrode plate 35 in a detachable manner. Furthermore, the electrode support 38 has a water-cooling structure made of a conductive material such as aluminum with an anodized surface. A gas diffusion chamber 40 is provided inside the electrode support 38. Multiple gas flow holes 41 extending downward from the gas diffusion chamber 40 and communicating with the ejection holes 37 extend from it.

[0065] A gas inlet 62 for introducing process gas into the gas diffusion chamber 40 is formed on the electrode support 38, and the gas inlet 62 is connected to a gas supply pipe 64. The gas supply pipe 64 is connected to the process gas supply source 66 via a valve 70 and a mass flow controller (MFC) 68. In the case of etching the semiconductor wafer W, the process gas for etching is supplied from the process gas supply source 66 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 sprayed out into the plasma processing space in a spray-like manner through the gas flow holes 41 and the ejection holes 37. That is, the upper electrode 34 also functions as a spray head for supplying process gas into the plasma processing space.

[0066] The second electrode plate 35 is electrically connected to the power supply SB 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 the magnitude (absolute value) indicated by the control unit 95. The switch 47 controls the supply and disconnection of the negative DC voltage from the power supply SB to the second electrode plate 35.

[0067] Furthermore, the control unit 95 can be configured as a central processing unit (CPU) of a computer, capable of executing processing steps stored in the storage unit 97. When the user interface 96 is an input device such as a keyboard or buttons, commands can be input to the control unit 95 from the input device. When the user interface 96 is an output device such as a display, the processing results from the control unit 95 can be displayed.

[0068] A cylindrical grounding conductor 10a is disposed on the side wall of the chamber 10 at a position higher than the upper electrode 34. The grounding conductor 10a has a top wall at its upper part.

[0069] The stage 16, which functions as the lower electrode, is electrically connected to the power supply SA via a first matching unit 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 with periodically changing voltage and current waveforms, specifically an electrical signal output by a high-frequency power supply or a pulsed power supply. It also includes electrical signals amplified by an amplifier to produce any periodic signal. Furthermore, the stage 16 is electrically connected to the power supply SF via a second matching unit 88. In this example, the power supply SF is also a high-frequency power supply that generates a periodic signal, but its frequency differs from that of the power supply SA. The power supply SA is a power supply for generating plasma, outputting a first high-frequency power with a frequency of 13 MHz or higher, for example, 40 MHz. The power supply SF is a power supply for attracting ions, outputting a second high-frequency power with a frequency lower than that of the high-frequency power supply SA, specifically 27 MHz or lower, for example, 2 MHz. Alternatively, a pulsed power supply that periodically outputs a pulsed negative voltage can be used instead of the power supply SF to generate the periodic signal. As a pulse power supply, it can be a DC pulse power supply that periodically outputs a negative DC voltage, or a pulse power supply that instantaneously and periodically outputs a negative voltage.

[0070] When plasma is generated within chamber 10, the first matching device 87 matches the impedance of power supply SA with the load impedance so that the impedance of power supply SA appears to be identical to the load impedance. Similarly, when plasma is generated within chamber 10, the second matching device 88 matches the impedance of power supply SF with the load impedance so that the impedance of power supply SF appears to be identical to the load impedance.

[0071] An exhaust port is provided at the bottom of the chamber 10, which is connected to an exhaust device 84 via an exhaust pipe. The exhaust device 84 has a vacuum pump such as a turbomolecular pump, which can reduce the pressure inside the chamber 10 to the desired vacuum level. In addition, an opening 85 for loading and unloading the semiconductor wafer W is provided on the side wall of the chamber 10, and the opening 85 can be opened and closed by a gate valve 86.

[0072] A deposition shield is provided along the inner wall of the chamber 10 to prevent etching byproducts (deposits) from adhering to the inner wall of the chamber 10. Additionally, the deposition shield is also provided on the outer periphery of the insulating member 26. An venting plate (not shown) is provided between the deposition shield on the chamber wall side and the deposition shield on the insulating member 26 side at the bottom of the chamber 10. For example, a material coated with a ceramic such as Y₂O₃ on aluminum can be appropriately used as the deposition shield and the venting plate. The deposition shield can be electrically connected to a ground potential (ground) to prevent abnormal discharge within the chamber 10.

[0073] Each component of the plasma processing apparatus 1 is controlled by a control unit 95. The control unit 95 is connected to a user interface 96, which includes a keyboard for process managers to input commands and manage the plasma processing apparatus 1, and a display that visually displays the operating status of the plasma processing apparatus 1.

[0074] As a program, there are control programs for implementing various processes performed by the plasma processing apparatus 1 under the control of the control unit 95, and programs for executing processes by each component of the plasma processing apparatus 1 according to processing conditions. These programs and the process indicating the processing conditions are stored in the storage unit 97, which is connected to the control unit 95. The storage unit 97 is, for example, a hard disk or a semiconductor memory. Alternatively, the storage unit 97 can be a portable storage medium that can be read by a computer. In this case, the control unit 95 obtains the control programs 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 DVD.

[0075] The control unit 95 reads any process from the storage unit 97 and executes the read process based on instructions received from the user via the user interface 96, thereby controlling each part of the plasma processing apparatus 1 to perform a prescribed plasma processing on the semiconductor wafer W. Furthermore, the plasma processing apparatus 1 of this embodiment includes a control unit 95, a user interface 96, and a storage unit 97.

[0076] In the plasma processing apparatus 1 configured as described above, when etching a semiconductor wafer W, firstly, the gate valve 86 is opened, and the semiconductor wafer W to be etched is moved into the chamber 10 through the opening 85. Next, the semiconductor wafer W is placed on an electrostatic chuck 18. Then, a predetermined DC voltage is applied to the electrostatic chuck 18 from the DC power supply SG to attract and hold the semiconductor wafer W on the upper surface of the electrostatic chuck 18.

[0077] Furthermore, a processing gas for etching and other purposes is supplied to the gas diffusion chamber 40 from the processing gas supply source 66 at a predetermined flow rate, and this processing gas is supplied into the chamber 10 via the gas flow port 41 and the ejection port 37. Additionally, the chamber 10 is vented by the exhaust device 84 to control the pressure within the chamber 10 to a predetermined pressure. With the processing gas supplied to the chamber 10, high-frequency power for plasma generation is applied to the stage 16 from the power supply SA, and high-frequency power for ion attraction is applied to the stage 16 from the power supply SF. Furthermore, a predetermined negative DC voltage (potential) is applied to the second electrode plate 35 from the power supply SB.

[0078] Between the upper electrode 34 and the mounting stage 16, a process gas ejected from the ejection hole 37 of the upper electrode 34 is plasmaized by a high-frequency power applied to the mounting stage 16. Free radicals and ions generated from this plasma are used to etch the semiconductor wafer W. The above process is performed according to instructions from the control unit 95.

[0079] Next, the potential of the auxiliary electrode will be explained.

[0080] Figure 2 It means Figure 1 The diagram shows a longitudinal cross-sectional view of the basic structure of the main part of the plasma processing device.

[0081] An edge ring ER and an auxiliary electrode AUX are mounted on an insulating member 26 comprising multiple components, including a quartz ring. The portion of the insulating member 26 where the edge ring ER is mounted is made relatively thin, allowing high-frequency currents from power supplies SA and SF to flow to the edge ring ER via a mounting stage 16. The auxiliary electrode AUX is coupled to the edge ring ER via a parasitic capacitance C. Furthermore, because the portion of the insulating member 26 where the auxiliary electrode AUX is mounted is made relatively thin, high-frequency currents from power supplies SA and SF flow to the auxiliary electrode AUX via the mounting stage 16. Therefore, the auxiliary electrode AUX has a periodically varying potential. Additionally, since a self-bias voltage, which is a negative DC voltage, is generated at the auxiliary electrode AUX, the potential of the auxiliary electrode AUX varies periodically with respect to the self-bias voltage Vdc.

[0082] A DC voltage of -V2 is applied from the power source SB to the second electrode plate 35 facing the auxiliary electrode AUX. Electrons with negative charges (-) move according 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.

[0083] Figure 3 This is a graph showing the relationship between the vertical position Z and the potential V(au), schematically representing the potential distribution between the auxiliary electrode AUX and the second electrode plate 35. Furthermore, the vertically upward direction of the plasma processing apparatus is set as the positive direction of the Z-axis, and each potential represents a voltage referenced to the ground potential (V=0). Additionally, 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 at the auxiliary electrode AUX.

[0084] The potential of the auxiliary electrode AUX varies periodically between its maximum value Vmax and minimum value Vmin, with the self-bias voltage Vdc as a reference. When the potential of the auxiliary electrode AUX is at the self-bias voltage Vdc, the potential distribution is shown as a solid line. When the potential of the auxiliary electrode AUX is at its maximum value Vmax or minimum value Vmin, the potential distribution is shown as a dashed line. The sheath thickness between the auxiliary electrode AUX and the plasma varies according to the change in the potential of the auxiliary electrode AUX.

[0085] In the case of a thin sheath, electrons in the plasma near the auxiliary electrode AUX are subjected to a force from the high electric field applied perpendicularly to the surface of the auxiliary electrode AUX in the case of a thick sheath. Electrons subjected to this force are accelerated toward the second electrode plate 35 (towards the plasma) facing the auxiliary electrode AUX. Additionally, secondary electrons generated by collisions between ions and the auxiliary electrode AUX are similarly subjected to a force from the sheath electric field between the auxiliary electrode AUX and the plasma. These electrons are also accelerated toward the second electrode plate 35 (towards the plasma). Some of these accelerated electrons collide with particles in the plasma, contributing to an increase in plasma density. On the other hand, the remaining accelerated electrons that do not collide with particles in the plasma travel toward the second electrode plate 35.

[0086] Accelerated electrons traveling toward the second electrode plate 35 are repelled by the sheath electric field between the 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 the second electrode plate 35 is smaller than the difference between the plasma potential and the potential (wall potential) of the auxiliary electrode AUX (entry condition), the accelerated electrons enter the second electrode plate 35.

[0087] 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), then the accelerated electrons experience a repulsive force in the opposite direction to that towards the second electrode plate 35. That is, under this reflection condition, the accelerated electrons experience a greater repulsive force than the force from the sheath electric field between the plasma potential and the auxiliary electrode AUX, and are accelerated towards the plasma (towards the auxiliary electrode AUX). A portion of the accelerated electrons collide with particles in the plasma, contributing to an increase in plasma density.

[0088] Therefore, the potential of the second electrode plate 35 is set such 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 did not collide with particles in the plasma and did not contribute to increasing plasma density to return to the plasma, thus contributing to increasing plasma density. Furthermore, the potential of the auxiliary electrode AUX periodically varies between its maximum value Vmax and minimum value Vmin, based on the self-bias voltage Vdc. Additionally, the plasma potential is higher than the potential of the auxiliary electrode AUX. Therefore, even when the potential of the second electrode plate 35 is grounded (V = 0), during periods 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.

[0089] However, the auxiliary electrode AUX has a longer period of negative potential, so most of the accelerated electrons that do not collide with particles in the plasma have difficulty entering the second electrode plate 35 to help increase the plasma density.

[0090] Therefore, in this method, a negative DC voltage -V2 is applied to the second electrode plate 35, the magnitude (absolute value) of which is greater than or equal to the magnitude (absolute value) of the negative self-bias voltage Vdc generated at the auxiliary electrode AUX. By setting the magnitude (absolute value) of the negative DC voltage -V2 to be greater than or equal to 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 return to the plasma. Thus, plasma can be efficiently generated even at the periphery of the substrate where the plasma density is low. Therefore, the uniformity of the plasma can be improved.

[0091] As explained 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 can be applied to electrons moving toward the second electrode plate 35, thereby controlling the plasma density near the second electrode plate 35. When a repulsive force is applied to these electrons, they move away from the second electrode plate 35, increasing the plasma density in the peripheral region of the substrate. This allows adjustment of the ratio of the plasma density at the center of the substrate mounting area to the plasma density in the peripheral region of the substrate. Consequently, the in-plane uniformity of the plasma can be improved.

[0092] The control unit 95 controls the output of the power supply SB (second power supply) to generate a negative DC voltage (-V2) on the second electrode plate 35, the magnitude of which is greater than the self-bias voltage (Vdc) generated by the auxiliary electrode AUX. Furthermore, here, the self-bias voltage (Vdc) is negative. When a negative DC voltage (-V2) is supplied to the second electrode plate 35, a repulsive force is applied to electrons moving towards the second electrode plate 35, causing the electrons to be reflected. The reflected electrons travel towards the plasma region, contributing to plasma generation, thus increasing the plasma density in the region surrounding the substrate. Therefore, the in-plane uniformity of the plasma can be improved. This control can also be applied to all other embodiments.

[0093] Next, use Figures 4-7 The shape of each electrode will be explained in detail.

[0094] Figure 4 This is a diagram showing the longitudinal cross-sectional structure of the main part of the plasma processing device.

[0095] exist Figure 2 In the basic configuration of the plasma processing apparatus shown, the surfaces of the second electrode plate 35 and the auxiliary electrode AUX are flat surfaces. However, in this example, at least one of the surfaces of the second electrode plate 35 and the auxiliary electrode AUX has a recess D. It is also possible that the electrode portion of the other electrode is located on the normal to the surface facing the recess D of one electrode. Figure 4 In the plasma processing apparatus shown, the lower surface of the second electrode plate 35 is machined into a concave surface, forming an annular recess D. The annular recess D surrounds the vertical central axis of the peripheral region of the substrate. The surface of the recess D is a continuous curved surface, like a parabola. As an example, the upper surface of the auxiliary electrode AUX shown is a flat surface, which is either coplanar with or parallel to the substrate mounting area. The normal to the surface of the recess D of the second electrode plate 35 intersects the upper surface of the auxiliary electrode AUX. That is, the auxiliary electrode AUX is located on the normal to the surface of the recess D of the second electrode plate 35.

[0096] In this example, the lower surface of the second electrode plate 35 has a recess D, therefore, compared to Figure 2 In this case, 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 within the central region in the annular width direction increases. The central region in the annular width direction is the region located between the outer and inner peripheral regions of the annular auxiliary electrode AUX. 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 annular width direction of the auxiliary electrode AUX. The accelerated electrons accumulate toward the central region in the annular width direction of the auxiliary electrode AUX, thus suppressing the increase in plasma density on the substrate mounting area side and improving the in-plane uniformity of the plasma.

[0097] The center position of the lower surface of the second electrode plate 35 in the width direction (radial direction) is parallel to the horizontal plane P of the upper surface of the auxiliary electrode AUX including the lower part. HZN2 The distance between them (shortest distance ΔH2) can be compared to Figure 2 In this case, the distance is narrow. In other words, the lower surface of the second electrode plate 35 is located further below the lower surface of the first electrode plate 36. The center position of the lower surface of the second electrode plate 35 in the width direction (radial) is perpendicular to the horizontal plane P containing the lower surface of the first electrode plate 36. HZN1 The distance between them is the shortest distance ΔH1. As a result, the electric field of the peripheral part (second electrode plate 35) is stronger than that of the central part (first electrode plate 36), thus increasing the plasma density of the peripheral part and improving the uniformity of the plasma.

[0098] As described above, the gap ΔH2 between the second electrode plate 35 (second upper electrode) and the auxiliary electrode AUX (second lower electrode) is narrower than the gap between the first electrode plate 36 and the mounting stage 16 (ΔH1 + ΔH2 + vertical distance from the surface of the auxiliary electrode AUX to the surface of the mounting stage (16)). Furthermore, ΔH2 < ΔH1 + ΔH2. Therefore, the electric field in the peripheral region of the substrate (the region between the second electrode plate 35 and the auxiliary electrode AUX) can be strengthened, thereby increasing the plasma density in that region. Additionally, as... Figure 4 As shown in the example, by lowering the height of the second electrode plate 35, the plasma density in the lower region of the second electrode plate 35 can be increased. Therefore, the in-plane uniformity of the plasma can be improved. This configuration can also be applied to all other embodiments.

[0099] Furthermore, the longitudinal cross-sectional shape of the recess D may not be a curved shape.

[0100] Figure 5 This is a diagram showing the longitudinal cross-sectional structure of the main part of the plasma processing device; only the shape of the recess D is similar to... Figure 4 The apparatus differs. Specifically, in this example, the lower surface of the second electrode plate 35 is machined into a shape after removing the trapezoidal shape within a longitudinal section along the vertical central axis of the substrate mounting area to form a recess D. The recess D can also be formed by a conical surface. The conical surface is approximately planar within a small area. The intersection of the conical surface and the longitudinal section along the vertical central axis of the substrate mounting area is not a curve, but a line segment. The outer conical surface surrounds the vertical central axis of the substrate mounting area, thus having a truncated cone shape that tapers towards the vertical. Similarly, the inner conical surface surrounds the vertical central axis of the substrate mounting area, thus having a truncated cone shape that tapers towards the vertical.

[0101] The tilt angle of the conical surface can be set to the angle at which the normal of the conical surface intersects the auxiliary electrode AUX. Therefore, the auxiliary electrode AUX is located on the normal of the surface (conical surface) of the recess D of the second electrode plate 35. More preferably, the tilt angle of the conical surface is such that the intersection point of the plurality of normals of the lower surface of the second electrode plate 35 with the upper surface of the auxiliary electrode AUX exists within the central region in the annular width direction. This central region in the annular width direction is the region located between the outer and inner peripheral regions of the annular auxiliary electrode AUX. Since the intersection points of the plurality of normals of the conical surface of the second electrode plate 35 with the auxiliary electrode AUX are concentrated within the central region in the annular width direction, it can achieve the effect of... Figure 4 The same effect is achieved in the same situation.

[0102] The recess D can also be located on the auxiliary electrode AUX.

[0103] Figure 6 This is a diagram showing the longitudinal cross-sectional structure of the periphery of a substrate in a plasma processing apparatus. In this example, the auxiliary electrode AUX is shown with a recessed portion D. Figure 4 Compared to the shape of the recess D shown, the shape of the recess D is flipped vertically, but otherwise identical. The surface of the recess D is a continuous curved surface like a parabola. The normal to the surface of the recess D facing the auxiliary electrode AUX intersects 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 facing the auxiliary electrode AUX. Even when the recess D is provided on the auxiliary electrode AUX, electrons accumulate towards the central region in the circumferential width direction of the second electrode plate 35. Therefore, it is possible to further suppress the increase in plasma density in the central part of the substrate mounting area and improve the in-plane uniformity of the plasma.

[0104] Figure 7 This is a diagram showing the longitudinal cross-sectional structure around the substrate in a plasma processing device.

[0105] This example also illustrates that the auxiliary electrode AUX has a recessed portion D. (And...) Figure 5Comparing the shapes of the recesses D shown, the shape of the recesses D is flipped vertically, but otherwise identical. Recess D is composed of... Figure 5 The cone surface is constructed in the same way as in the case of the auxiliary electrode AUX. The angle of the cone surface can be set to the angle at which the normal of the cone surface intersects with the second electrode plate 35. Therefore, the second electrode plate 35 is located on the normal of the surface (cone surface) of the recess D for the auxiliary electrode AUX. More preferably, the angle of the cone surface is such that the intersection point of the multiple normals of the upper surface of the auxiliary electrode AUX with the lower surface of the second electrode plate 35 exists in the central region of the annular width direction of the second electrode plate 35. This central region of the annular width direction is the region of the annular second electrode plate 35 located between its outer peripheral region and inner peripheral region. Thus, it can achieve the same effect as Figure 5 The same effect applies to the same situation.

[0106] In addition, the recess D can also be provided on both the auxiliary electrode AUX and the second electrode plate 35.

[0107] Figure 8 This is a diagram illustrating an example of the positional relationship between the auxiliary electrode AUX and the second electrode plate 35.

[0108] In this example, both the auxiliary electrode AUX and the second electrode plate 25 have recesses D. The recess D of the second electrode plate 35 lies on the normal NAUX of the surface of the recess D of the auxiliary electrode AUX. Additionally, the recess D of the auxiliary electrode AUX lies on the normal N35 of the surface of the recess D of the second electrode plate 35.

[0109] Multiple normals (NAUX, NAUXa) can be set on the surface of the recess D of the auxiliary electrode AUX. The central normal NAUX is the normal at the deepest part of the recess D in the auxiliary electrode AUX. The normal NAUX extends toward the deepest part of the recess D of the second electrode plate 35.

[0110] Multiple normals (N35, N35a) can also be set on the surface of the recess D of the second electrode plate 35. The central normal N35 is the normal at the deepest part of the recess D of the second electrode plate 35. Normal N35 extends toward the deepest part of the recess D of the auxiliary electrode AUX.

[0111] With the XYZ three-dimensional orthogonal coordinate system established, the horizontal plane is represented by the XY plane. In this example, the XZ plane is used to show the longitudinal section along the vertical central axis passing through the substrate mounting area. When this central axis is set as the Z-axis, the shape of the recess D of the auxiliary electrode AUX, 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, viewed from the Z-axis direction, is also a ring centered on the Z-axis.

[0112] In the XZ plane, electrons near the surface of the recess D of the auxiliary electrode AUX are accelerated toward the recess D of the second electrode plate 35. The accelerated electrons then accumulate toward the second electrode plate 35. Conversely, in the XZ plane, electrons near the surface of the recess D of the second electrode plate 35 are accelerated toward the recess D of the auxiliary electrode AUX. These accelerated electrons then accumulate toward the auxiliary electrode AUX. Therefore, the plasma density in the peripheral region of the substrate increases. This suppresses the increase in plasma density in the central portion of the substrate mounting region. Consequently, the in-plane uniformity of the plasma can be improved.

[0113] Next, the power supply for the auxiliary electrode will be explained.

[0114] The example described above, supplying high-frequency power to the auxiliary electrode AUX via the edge ring ER or the mounting stage 16, is also illustrated. However, the auxiliary electrode AUX can also be configured to be directly connected to a high-frequency power supply via wiring. Alternatively, an electrode can be disposed within the dielectric of the lower portion of the auxiliary electrode AUX, and this electrode can be connected to the high-frequency power supply via wiring. The electrode within the dielectric of the lower portion of the auxiliary electrode AUX is capacitively coupled to the auxiliary electrode AUX, thereby enabling the supply of high-frequency power to the auxiliary electrode AUX. The power supply connected to the auxiliary electrode AUX can be power supply SA and / or power supply SF, or it can be a high-frequency power supply, pulsed power supply, or DC power supply different from power supply SA and power supply SF.

[0115] Figure 9 This is a diagram showing the longitudinal cross-sectional structure of the periphery of a substrate in a plasma processing apparatus according to an exemplary embodiment. This example shows a case where multiple power supplies are connected to an auxiliary electrode AUX via wiring.

[0116] The power supply SA is connected to the mounting stage 16 via the first matching unit 87, the common wiring L0, and the first branch wiring L1. Additionally, the power supply SA is connected to the auxiliary electrode AUX via the first matching unit 87, the common wiring L0, and the second branch wiring L2. The common wiring L0 branches into the first branch wiring L1 and the second branch wiring L2, and the second branch wiring L2 is connected to the auxiliary electrode AUX without passing through the mounting stage 16. In this example, the power supply SA is a high-frequency power supply used to generate plasma.

[0117] The power supply SF is connected to the stage 16 via the second matching connector 88, the common wiring L0, and the first branch wiring L1. Additionally, the power supply SF is connected to the auxiliary electrode AUX via the second matching connector 88, the common wiring L0, and the second branch wiring L2. In this example, the power supply SF is a high-frequency power supply used for ion attraction.

[0118] 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 can be a circuit with any structure and variable impedance. In one example, the first variable impedance circuit 81 and / or the second variable impedance circuit 82 can include a variable capacitance capacitor.

[0119] Alternatively, a sensor 83 for measuring the self-bias voltage or voltage waveform generated at the auxiliary electrode AUX can be provided between the auxiliary electrode AUX and the second variable impedance circuit 82. The control unit 95 can also calculate the peak-to-peak voltage (Vpp) based on this voltage waveform. In this case, the magnitude of the self-bias voltage or peak-to-peak voltage obtained by the sensor 83 can be fed back to... Figure 1 The control unit 95 shown. Figure 1 The control unit 95 shown can control power supply SA, power supply SF, power supply SB, first variable impedance circuit 81 and / or second variable impedance circuit 82.

[0120] Figure 1 The control unit 95 shown controls the output of these power supplies and controls the impedance of the variable impedance circuit. For example, when the plasma density in the area surrounding the substrate is lower than a reference value, the control unit 95 controls the increase of the plasma density. For example, the control unit 95 reduces the impedance of the second variable impedance circuit 82 to increase the electric current flowing in the second branch wiring L2. Additionally, the control unit 95... Figure 3 As shown, make the power supply SB ( Figure 1 The magnitude (absolute value) of the negative bias voltage (-V2) output increases. This feedback control increases the plasma density in the region surrounding the substrate. Alternatively, if the plasma density in the region surrounding the substrate is above a reference value, the control unit 95 controls the plasma density to decrease using the opposite method described above.

[0121] In this plasma processing apparatus, a first high-frequency power and a second high-frequency power are supplied to the auxiliary electrode AUX from power supplies SA and SF via a second variable impedance circuit 82. Therefore, the high-frequency power supplied to the central and peripheral portions of the stage 16 can be adjusted, and the potential of the auxiliary electrode AUX can be actively controlled. Thus, control can be performed to further improve the in-plane uniformity of the plasma.

[0122] Alternatively, an electrode can be disposed inside the dielectric at the lower part of the auxiliary electrode AUX, and various power supplies, as illustrated, can be connected to the electrode instead of the auxiliary electrode AUX.

[0123] The plasma processing apparatus of this example has a power transmission path (third power supply line) via a first branch wiring L1 and a power transmission path (fourth power supply line) via a second branch wiring L2. The third power supply line is used to provide a periodic signal output from the power supply SA (first power supply) to the stage 16 (first lower electrode). The fourth power supply line is used to provide a 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. Power distribution can be achieved using only one of these variable impedance circuits.

[0124] By adjusting the impedances of the first variable impedance circuit 81 and the second variable impedance circuit 82, the amount of power supplied to the lower electrode can be adjusted. Therefore, the ratio of power supplied to the stage 16 and the auxiliary electrode AUX can be adjusted. The plasma density depends on the amount of power supplied to the electrode. Therefore, by adjusting the ratio of the power supply, the in-plane uniformity of the plasma can be improved.

[0125] Figure 10 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in the plasma processing apparatus according to the illustrated embodiment.

[0126] The power supply SA is connected to the stage 16 via a first matching unit 87. In this example, the power supply SA is a high-frequency power supply for generating plasma. High-frequency power is supplied from the power supply SA to the stage 16.

[0127] The power supply SF is connected to the stage 16 via a second matching device 88. In this example, the power supply SF is a high-frequency power supply used for ion attraction. Second high-frequency power is supplied from the power supply SF to the stage 16.

[0128] The power supply SE is connected to the auxiliary electrode AUX via 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 power supply SA used to generate plasma, the plasma density in the substrate mounting region can be adjusted. The power supply SE is a different power supply than the power supplies SA and SF, and can be a high-frequency power supply. Alternatively, the power supply SE can also be a pulsed power supply.

[0129] The plasma processing apparatus in this example includes a power supply SE (fifth power supply) that supplies a periodic signal to the auxiliary electrode AUX. When a periodic signal is supplied to the auxiliary electrode AUX, the density of the plasma generated near the auxiliary electrode AUX can be increased.

[0130] The plasma processing apparatus in this example also has a sensor 83 for measuring the self-bias voltage or voltage waveform generated at the auxiliary electrode AUX. Figure 1 The control unit 95 shown controls the output of the power supply SB (second power supply) based on the measured value obtained from the sensor 83. The measured value obtained from the sensor 83 is related to the amount of electrons reflected from the auxiliary electrode AUX, i.e., the plasma density in the region surrounding the substrate. Furthermore, 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 measured value. For example, if the plasma density corresponding to the measured value from the sensor 83 is lower than a reference value, the output of the power supply SB (the magnitude of the negative bias voltage) is increased. Conversely, if the plasma density corresponding to the measured value from the sensor 83 is higher than the reference value, the output of the power supply SB (the magnitude of the negative bias voltage) is decreased. Through this feedback control, control can be performed to bring the plasma density in the region surrounding the substrate closer to the reference value. Therefore, the in-plane uniformity of the plasma can be improved.

[0131] The plasma processing apparatus in 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 controls the output of the power supply SE (fifth power supply) based on the measured value obtained from the sensor 83. The measured value obtained from the sensor 83 is related to the amount of electrons reflected from the auxiliary electrode AUX, i.e., the plasma density in the substrate peripheral region. When the control unit 95 adjusts the output of the power supply SE based on the plasma density corresponding to the measured value, the plasma density in the substrate peripheral region can be controlled. For example, if the plasma density corresponding to the measured value from the sensor 83 is lower than a reference value, the output of the power supply SE (the magnitude and / or power of the negative bias amplitude center voltage) is increased. If the plasma density corresponding to the measured value from the sensor 83 is higher than the reference value, the output of the power supply SE (the magnitude and / or power of the negative bias amplitude center voltage) is decreased. Thus, control can be performed to bring the plasma density in the substrate peripheral region closer to the reference value. Through this feedback control, the in-plane uniformity of the plasma can be improved. Furthermore, the reference value and the correlation between the measured value and the plasma density can be pre-stored. Figure 1 The storage unit is located within 97.

[0132] Furthermore, a power supply SD (fourth power supply) that generates DC voltage can be used instead of power supply SE (fifth power supply). Alternatively, the power supply SD that generates DC voltage can be connected to the auxiliary electrode AUX instead of power supply SE. That is, the plasma processing apparatus in this example can be equipped with a power supply SD (fourth power supply) that supplies DC voltage to the auxiliary electrode AUX (second lower electrode).

[0133] Alternatively, the power supply SA, which is connected to the stage 16 and generates the first high-frequency power (a periodic signal), can be used instead of the power supply SA described later. Figure 12 or Figure 16 The power supply SC (third power supply) shown is connected to the second electrode plate 35, or the power supply SC (third power supply) can be connected to the second electrode plate 35 in addition to the power supply SA. In this case, the output from the power supply SC can also be... Figure 12 Branch as shown.

[0134] When a DC voltage is supplied to the auxiliary electrode AUX, a force can be applied to electrons moving towards the auxiliary electrode AUX, thus controlling the plasma density near the auxiliary electrode AUX. For example, if the plasma density corresponding to the measurement value of 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 (the direction of the plasma). These electrons contribute to plasma generation, thus increasing the plasma density in the area surrounding the substrate in a manner close to the reference value. Conversely, if the plasma density corresponding to the measurement value of sensor 83 is 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, Figure 1 The control unit 95 shown can control the plasma density in the area surrounding the substrate and improve the in-plane uniformity of the plasma density.

[0135] In this example, the plasma processing apparatus uses a power supply SE (SD) different from the power supplies SA and SF to supply high-frequency power to the auxiliary electrode AUX. Therefore, the high-frequency power supplied from the power supply SE (SD) to the peripheral region of the substrate can be adjusted independently of the power supplies SA and SF that generate plasma in the center of the stage 16, and the potential of the auxiliary electrode AUX can be actively controlled. Thus, control can be performed to further improve the in-plane uniformity of the plasma.

[0136] Figure 11 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in the plasma processing apparatus according to the illustrated embodiment. As shown in this example, an electrode 73 for supplying power can be provided inside the insulating member 26 located below the auxiliary electrode AUX. Figure 11 The plasma processing apparatus shown connects the power supply SE (SD) to the electrode 73 for supplying power via sensor 83, rather than directly to... Figure 10 The auxiliary electrode AUX in the circuit. Regarding... Figure 11 The structure, apart from controlling the potential supplied to the auxiliary electrode AUX via electrode 73, is similar to... Figure 10 The same structure achieves the same effect.

[0137] That is, electrode 73 is connected to power supply SE (SD). A sensor 83 for measuring the self-bias voltage or voltage waveform generated at auxiliary electrode AUX can be placed between electrode 73 and power supply SE (SD). Sensor 83 can be directly connected to auxiliary electrode AUX. The self-bias voltage or voltage waveform (or the magnitude of the inter-peak voltage) acquired by sensor 83 is fed back to control unit 95. Figure 1 ),and Figure 10 The plasma density is controlled in the same manner. The power supply SE (SD) or power supply SB (SD) can be controlled via the control unit 95. Figure 1 ) output.

[0138] In this example, the plasma processing apparatus uses a power supply SE (SD) different from the power supplies SA and SF to supply high-frequency power to the auxiliary electrode AUX. Therefore, the high-frequency power supplied from the power supply SE (SD) to the peripheral region of the substrate can be adjusted independently of the power supplies SA and SF that generate plasma in the center of the stage 16, and the potential of the auxiliary electrode AUX can be actively controlled. Thus, control can be performed to further improve the in-plane uniformity of the plasma.

[0139] Various connection methods can be conceived regarding the relationship between the auxiliary electrode AUX and the power supply. For example, the power supply SE, which generates high-frequency power, can be connected to electrode 73. Alternatively, the power supply SD, which generates DC voltage, can be connected to electrode 73 instead of the high-frequency power supply SE. Connections such as connecting the high-frequency power supply SE to the auxiliary electrode AUX while the high-frequency power supply SE is connected to electrode 73 are also conceivable.

[0140] The power supply SD can be a DC power supply. The potential of the auxiliary electrode AUX (the voltage between it and ground potential) is... Figure 3 The self-bias voltage Vdc (amplitude center voltage) shown is periodically varied with reference. Therefore, the average potential of the auxiliary electrode AUX is Vdc. The potential of the auxiliary electrode AUX can be directly varied with an AC power supply. Alternatively, the potential of the auxiliary electrode AUX can be varied in a coupled manner with the AC potential supplied to the mounting stage 16. Here, when a negative DC voltage Va is applied to the electrode 73 via the power supply SD, the average potential of the auxiliary electrode AUX is the value obtained by adding Vdc and Va. That is, by connecting the power supply SD, which is a DC power supply, to the electrode 73 or the auxiliary electrode AUX, the periodically varying potential of the auxiliary electrode AUX can be corrected as a whole.

[0141] Furthermore, it is also possible to construct a structure where both power supply SE and power supply SD are high-frequency power supplies. In this case, a first high-frequency power and a second high-frequency power are provided to the auxiliary electrode AUX or electrode 73.

[0142] The example of applying a DC voltage from the power supply SB to the second electrode plate 35 was described above. Alternatively, an AC voltage-generating power supply SC can be connected to the second electrode plate 35 instead of the DC voltage-generating power supply SB. Next, the case of applying high-frequency power to the second electrode plate 35 will be described.

[0143] Figure 12 This is a diagram showing the longitudinal cross-sectional structure of the periphery of the substrate in the plasma processing apparatus according to the illustrated embodiment. In this example, the plasma processing apparatus shows that the substrate 16 has been removed... Figure 11 The example shown is of a power supply SA for generating plasma, with the power supply SC instead connected to the second electrode plate 35 and the electrode support 38 (first electrode plate 36). In other words, this example illustrates a case where the power supply for generating plasma is connected to the upper electrode instead of the lower electrode. Alternatively, the power supply for generating plasma could be connected to the lower electrode, and in addition, also to the upper electrode.

[0144] The power supply SC is connected to the electrode support 38 (first electrode plate 36) via the first matching unit 87, the common wiring L0, and the first branch wiring L1. In this example, the power supply SC is a high-frequency power supply for generating plasma, and a first high-frequency power is supplied from the power supply SC to the electrode support 38 and the first electrode plate 36 via the first branch wiring L1.

[0145] Additionally, the power supply SC is connected to the second electrode plate 35 via the first matching unit 87, the common wiring L0, and the second branch wiring L2. The common wiring L0 branches into the first branch wiring L1 and the 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. In this example, the power supply SC supplies the first high-frequency power to the second electrode plate 35 via the second branch wiring L2.

[0146] The power supply SF is connected to the stage 16 via the second matching unit 8. In this example, the power supply SF is a high-frequency power supply used for ion attraction.

[0147] The power supply SE is connected to the auxiliary electrode AXU via 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 power supply SE. Either power supply SE or power supply SD, or either power supply SD, can be connected to the auxiliary electrode AUX. The effect of using power supply SE (SD) is as described above.

[0148] Because high-frequency power is supplied to the second electrode plate 35, a self-bias voltage as a negative DC voltage is generated on the second electrode plate 35. Therefore, the magnitude (absolute value) of the self-bias voltage generated on the second electrode plate 35 is set to be the same as the magnitude (absolute value) of the self-bias voltage generated on the auxiliary electrode AUX. Alternatively, the magnitude (absolute value) of the self-bias voltage generated on the second electrode plate 35 may be set to be greater than the magnitude (absolute value) of the self-bias voltage generated on the auxiliary electrode AUX. As a result, accelerated electrons that have not collided with particles in the plasma can be efficiently returned to the plasma.

[0149] 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 can be a circuit with any structure and variable impedance. In one example, the first variable impedance circuit 81a and / or the second variable impedance circuit 82a can include a variable capacitance capacitor.

[0150] Alternatively, a sensor 83a for measuring the self-bias voltage or voltage waveform generated by the second electrode plate 35 can 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 inter-peak voltage) obtained by the sensor 83a can be fed back to... Figure 1 The control unit 95 shown performs the same feedback control as described above. Figure 1 The control unit 95 shown can control the power supply SC, power supply SF, power supply SE (SD), first variable impedance circuit 81a and / or second variable impedance circuit 82a to set the plasma density in the peripheral region of the substrate to a reference value as a target.

[0151] The plasma processing apparatus in this example has a power supply SC (third power supply) that supplies a periodic signal to the second electrode plate 35. When a periodic signal is supplied to the second electrode plate 35, the density of the plasma generated near the second electrode plate 35 can be increased. Furthermore, in Figure 12 In this process, a power supply SF (first power source) that supplies a periodic signal to the stage 16 (first lower electrode) is used to attract ions.

[0152] The plasma processing apparatus of this example has a power transmission path (first power supply line) via a first branch wiring L1 and a power transmission path (second power supply line) via a second branch wiring L2. The first power supply line is used to supply a periodic signal output from the power source SC (third power source) to the first electrode plate 36 (first upper electrode) via the electrode support 38. The second power supply line is used to supply a periodic signal output from the power source SC to the 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).

[0153] By adjusting the impedance of the first variable impedance circuit 81a and / or the second variable impedance circuit 82a, the amount of power supplied to the 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. The plasma density depends on the amount of power supplied to the electrode. Therefore, by adjusting the ratio of the power supply, the in-plane uniformity of the plasma can be improved.

[0154] In addition, in this example, it is also possible to... Figures 9-11 Connect the power supply SA to the stage 16 as shown in the example.

[0155] As explained above, Figure 12 The plasma processing apparatus includes a sensor 83 for measuring the self-bias voltage or voltage waveform generated at the auxiliary electrode AUX, and a sensor 83a for measuring the self-bias voltage or voltage waveform generated at the second electrode plate 35. Feedback control based on sensor output can be performed using only one of these sensors 83 and 83a. Figure 1 The control unit 95 shown controls the impedance of the first variable impedance circuit 81a and the impedance of the second variable impedance circuit 82a based on the measured values ​​obtained by sensors 83 and 83a. These measured values ​​are the self-bias voltage or voltage waveform (or the magnitude of the peak-to-peak voltage). Furthermore, as... Figure 9 As shown, high-frequency power can be supplied from power supplies SA and SF to the auxiliary electrode AUX on the lower side via a variable impedance circuit. In this case, Figure 1 The control unit 95 shown has a sensor 83 for measuring the self-bias voltage generated at the auxiliary electrode AUX (second lower electrode), and for controlling the circuit based on the measured value measured by the sensor 83. Figure 9 The impedances of the variable impedance circuits 81 and 82 shown.

[0156] The transmittable electrical force varies depending on the impedance value. The plasma density in the area surrounding the substrate is related to the measured value. If, based on the measured value, the plasma density in the area surrounding the substrate is determined to be lower than a reference value, the control unit 95 controls to increase the plasma density. If, based on the measured value, the plasma density in the area surrounding the substrate is determined to be higher than the reference value, the control unit 95 controls to decrease the plasma density. The reference value and the correlation between the measured value and the plasma density can also be pre-stored. Figure 1 The storage unit is located within 97.

[0157] The method for increasing the plasma density in the peripheral region of the substrate is as described above. The impedance of the variable impedance circuit controls the plasma density generated in the space on the substrate mounting area (the space between the mounting stage 16 and the first electrode plate 36) and the space in the peripheral region of the substrate (the space between the auxiliary electrode AUX and the second electrode plate 35). The measured value obtained by the sensor is related to the plasma density in the peripheral region of the substrate. Therefore, the control unit 95 adjusts the impedance of the variable impedance circuits 81a and 82a according to the plasma density corresponding to the measured value, thereby adjusting the amount of power supplied to the electrodes connected to the variable impedance circuits 81a and 82a. The plasma density depends on the amount of power supplied to the target electrode. Therefore, by adjusting the ratio of the amount of power supplied based on the measured values ​​of the sensors 83 and 83a, the in-plane uniformity of the plasma can be improved.

[0158] Figure 13 This is a diagram showing the longitudinal cross-sectional structure of the periphery of a substrate in a plasma processing apparatus according to an exemplary embodiment. Figure 12 Compared to the plasma processing device shown, the only difference in this example is the power supply connection on the upper side; the other structures are the same.

[0159] Power supply SC is connected to electrode support 38 (first electrode plate 36) via first matching adapter 87. Power supply SB is connected to second electrode plate 35 via sensor 83a. Power supply SC is... Figure 12 The diagram shows a high-frequency power supply for generating plasma. The upper power supply SB can have the same structure as the lower power supply SE (SD). In other words, the power supply SB is a DC power supply that generates DC voltage, but it can also be a pulsed power supply or a high-frequency power supply. In addition to the power supply SB (DC voltage), other power supplies (pulsed power supply, high-frequency power supply) are connected to the second electrode plate 35.

[0160] In any case, as Figure 3As shown, the average (or effective) potential of the second electrode plate 35 is greater than or equal to the average (or effective) potential of the auxiliary electrode AUX (condition 1). The outputs of power supplies SB and SE (SD) are set to satisfy (condition 1). In order to satisfy (condition 1), in addition to controlling the outputs of power supplies SB and SE (SD), power supplies SC and SF can also be controlled. That is, the output of at least one of power supplies SB, SE (SD), SC, and SF can be controlled to satisfy (condition 1). When the power supply is a high-frequency power supply (AC power supply), the above-mentioned variable impedance circuit can be set between the power supply and the electrode. The impedance of these variable impedance circuits can also be controlled to satisfy (condition 1). In addition, these controls can also be performed based on the values ​​of the self-bias voltage or voltage waveform (or the magnitude of the inter-peak voltage) generated by the second electrode plate 35 and / or the auxiliary electrode AUX obtained from sensors 83, 83a. The feedback control method is the same as the control described above.

[0161] This allows for the efficient return of accelerated electrons that did not collide with particles in the plasma to the plasma, and enables efficient plasma generation even at the periphery of a substrate with low plasma density. Consequently, the uniformity of the plasma can be improved.

[0162] The second electrode plate 35 and the auxiliary electrode AUX described above can face each other at the periphery of the substrate, or they can be arranged without being parallel to the substrate mounting area. Furthermore, the second electrode plate 35 and the auxiliary electrode AUX may not need to be connected to a DC power supply or a high-frequency power supply.

[0163] Figure 14 This is a diagram showing the longitudinal cross-sectional structure around the substrate in a plasma processing device.

[0164] As shown in the figure, the insulating member 26 has an inclined surface, on which the auxiliary electrode AUX is mounted. The auxiliary electrode AUX is electrically connected to the chamber 10 via wiring and is grounded. The shape of the auxiliary electrode AUX indicates that... Figure 6 The shape shown is the same as the linear shape, but the shape is not limited to this. The shape of the recess D can also be... Figure 7 The shape shown can also be flat without the recess D. A second electrode plate 35b is provided facing the auxiliary electrode AUX, and this second electrode plate 35b has a flat surface inclined relative to the horizontal direction. That is, the second electrode plate 35b is located on the normal line of the surface of the recess D facing the auxiliary electrode AUX. The second electrode plate 35b is grounded via the sidewall of the chamber 10. The second electrode plate 35b can be formed by the sidewall of the chamber 10 or by a deposited shielding member. In addition, as Figure 4 or Figure 5As shown in the second electrode plate 35, the recess D may be provided on the second electrode plate 35b instead of on the auxiliary electrode AUX side. Alternatively, the recess D may be provided on both the auxiliary electrode AUX and the second electrode plate 35b.

[0165] In addition, Figure 14 In, it does not exist. Figure 13 The horizontal end of the first electrode plate 36 in the insulating member 39 shown abuts against the inner circumferential 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.

[0166] In this plasma processing apparatus, an auxiliary electrode AUX with a recess D is placed on an inclined surface, and a second electrode plate 35b has a flat surface inclined relative to the horizontal direction and faces the auxiliary electrode AUX. That is, the normal of the bottom surface of the recess D configured for the auxiliary electrode AUX is inclined relative to the normal for the substrate mounting area.

[0167] In this plasma processing apparatus, the second electrode plate 35b and the auxiliary electrode AUX are grounded and have the same potential. The plasma PL generated between the stage 16 and the first electrode plate 36 diffuses into the space between the auxiliary electrode AUX and the second electrode plate 35b. The intensity of the sheath electric field is proportional to the difference between the plasma potential and the wall potential. Furthermore, the greater the bias power, the greater the plasma potential, and the plasma potential is maximum when the bias power is in positive phase. Therefore, a large potential gradient is generated between the potential of the grounded auxiliary electrode AUX and the plasma. In the case of a thin sheath, electrons in the plasma near the auxiliary electrode AUX are accelerated toward the second electrode plate 35b (towards 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. On the other hand, the remaining accelerated electrons that do not collide with particles in the plasma are repelled by the sheath electric field between the second electrode plate 35b and the plasma and return to the plasma. Furthermore, when the sheath is thin, electrons in the plasma near the second electrode plate 35b are also accelerated towards the plasma, repelled by the sheath electric field between the auxiliary electrode AUX and the plasma, and return to the plasma. Therefore, the reciprocating motion of accelerated electrons in the space between the second electrode plate 35b and the auxiliary electrode AUX increases the plasma density at the periphery of the substrate. This improves the uniformity of the plasma.

[0168] Alternatively, a high-frequency power supply and / or a DC power supply can be electrically connected to the auxiliary electrode AUX and the second electrode plate 35b to provide potential to the auxiliary electrode AUX and the second electrode plate 35b.

[0169] Figure 15This is a diagram illustrating an example of the positional relationship between the auxiliary electrode AUX and the second electrode plate 35b.

[0170] Both the auxiliary electrode AUX and the second electrode plate 35b have recesses D. Multiple normals (NAUX, NAUXa) can be defined on the surface of the recess D of the auxiliary electrode AUX. The normal NAUX extends towards the deepest part of the recess D of the second electrode plate 35b. The normal NAUX at the deepest part of the recess D of the auxiliary electrode AUX is inclined relative to the vertical direction (Z-axis direction).

[0171] Multiple normals (N35, N35a) can also be set on the surface of the recess D of the second electrode plate 35b. Normal N35 is the normal at the deepest part of the recess D of the second electrode plate 35. Normal N35 extends towards the deepest part of the recess D of the auxiliary electrode AUX. Normal N35 at the deepest part of the recess D of the second electrode plate 35b is also inclined relative to the vertical direction (Z-axis direction). Apart from this inclination, the shape of each recess D is similar to that in… Figure 8 The shapes described in the text are the same.

[0172] The normal N18 on 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 such that the normal NA UX (or N35) to the bottom surface of the recess D is tilted at an angle θ relative 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 aforementioned tilt angle θ, the intensity and shape of the plasma in the peripheral region of the substrate can be changed. The design freedom of the in-plane distribution of plasma density is increased, thus improving the in-plane uniformity of the plasma.

[0173] In the XZ plane, electrons near the surface of the recess D of the auxiliary electrode AUX are accelerated toward the recess D of the second electrode plate 35b. The accelerated electrons then accumulate toward the second electrode plate 35b. Conversely, in the XZ plane, electrons near the surface of the recess D of the second electrode plate 35b are accelerated toward the recess D of the auxiliary electrode AUX. These accelerated electrons then accumulate toward the auxiliary electrode AUX. Consequently, the plasma density in the peripheral region of the substrate increases. This suppresses the increase in plasma density in the central portion of the substrate mounting region. Therefore, the in-plane uniformity of the plasma can be improved.

[0174] Furthermore, the second electrode plate 35b may be formed by the inner wall of the chamber 10 (processing container) or by a deposit shielding element disposed along the inner wall of the chamber 10. Figure 1 The inner wall surface of the chamber 10 shown corresponds to these elements. In this case, the second electrode plate 35b also serves as the inner wall of the chamber or a deposit shield, thus reducing the number of components while achieving the aforementioned effects. Furthermore, Figure 14and Figure 15 The structure can also be applied to other implementation scenarios.

[0175] Figure 16 This is a diagram showing the connection relationship between the power source and the electrodes. The electrodes and power source described above can be electrically connected in various ways.

[0176] For example, in the above embodiment, the second electrode plate 35 (35b) and the auxiliary electrode AUX can be electrically grounded. In this case, the auxiliary electrode AUX is connected to the ground potential G1, and the second electrode plate 35 is connected to the ground potential G2. If 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 moving toward the sheath contribute to the generation of plasma, thus increasing the plasma density in the region surrounding the substrate. Therefore, the in-plane uniformity of the plasma can be improved.

[0177] As an electrode group located lower than the plasma generation region, there is a mounting stage 16 and an auxiliary electrode AUX. These electrode groups are connected to the power supply circuit group S used for the lower electrode group. DOWN Connection. Power circuit group S DOWN It 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.

[0178] As an electrode group located above the plasma generation region, there are a first electrode plate 36 and a second electrode plate 35. These electrode groups are compatible with the power supply circuit group S used for the upper electrode group. UP Connection. Power circuit group S UP It has a third power supply SC, a second power supply SB, a ground potential G2, and a distribution circuit DIV2 for distributing power.

[0179] like Figure 9 As shown, the structure of the distribution circuit DIV1 on the lower side is a circuit that includes a variable impedance circuit in the power transmission path. It is a circuit that changes the power supply ratio to the connected electrodes according to the values ​​of these impedances.

[0180] Power can be supplied from the lower power source to the stage 16 and the auxiliary electrode AUX via the distribution circuit DIV1. Power can also be supplied from the lower power source to the stage 16 and the auxiliary electrode AUX without going through the distribution circuit DIV1. The first power source SA is set to a high-frequency power source, and the power source SF used for ion attraction is set to a power source with a lower frequency than the first power source SA. The fourth power source SD is set to a DC power source, and the fifth power source SE is set to a high-frequency power source. Multiple combinations of these power sources exist.

[0181] The power supply SF for attracting ions is connected to the stage 16 via or without the distribution circuit DIV1. When the power supply for generating plasma is set as the first power supply SA, the first power supply SA can be connected to the stage 16 via or without the 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. Sensors for measuring the self-bias voltage or voltage waveform of the auxiliary electrode AUX can be installed in the connected paths. The outputs of the first power supply SA, the fourth power supply SD, and the fifth power supply SE can be connected to the stage 16 and the auxiliary electrode AUX via the distribution circuit DIV1. Sensors for measuring the self-bias voltage or voltage waveform can be configured in all power transmission paths, and control can be performed based on the above-described feedback method to improve the in-plane uniformity of the plasma.

[0182] like Figure 12 As shown, the upper distribution circuit DIV2 is a circuit that includes a variable impedance circuit in the power transmission path. It is a circuit that changes the power supply ratio to the connected electrodes according to the ratio of these impedances.

[0183] Power can be supplied from the upper power source 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 source to the first electrode plate 36 and the second electrode plate 35 without going through the distribution circuit DIV2. The third power source SC is a high-frequency power source. The second power source SB is a DC power source, but it can also be a pulse power source or a high-frequency power source. The second power source SB can have both a DC power source and a high-frequency power source (supplying power for periodic signals), and can be configured to apply DC voltage and AC voltage (high-frequency voltage) to the second electrode plate 35 respectively from these power sources.

[0184] When the power source for generating plasma is designated as the third power source SC, the third power source SC can be connected to the first electrode plate 36 via or without the 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. Sensors for measuring the self-bias voltage or voltage waveform of the second electrode plate 35 can be installed within the connected paths. The outputs of the third power source SC and the second power source SB can be connected to the first electrode plate 36 and the second electrode plate 35 via the distribution circuit DIV2. Sensors for measuring the self-bias voltage or voltage waveform can be configured in all power transmission paths, and control can be performed based on the aforementioned feedback method to improve the in-plane uniformity of the plasma. Feedback control that increases the in-plane uniformity of the plasma can be applied in all embodiments. Feedforward control can also be used instead of feedback control.

[0185] Additionally, when selecting the power supply circuit group S from the bottom side... DOWN When one of the aforementioned power supplies is connected to the auxiliary electrode AUX, it is possible to select the power supply circuit group S on the upper side. UP The power supply connected to the second electrode plate 35 can be combined with one of the aforementioned power supplies. For example, power supply SD can be selected as the lower power supply for applying a DC voltage, and power supply SB can be selected as the upper power supply for applying a DC voltage. Alternatively, power supply SD can be selected as the lower power supply for applying a DC voltage, and power supply SB can be selected as the upper power supply for applying an AC voltage (with a periodic signal). In this case, power supply SB can include both a power supply for applying a DC voltage and a power supply for applying an AC voltage. When power supply SB includes an AC power supply, it can be combined with... Figure 12 The power supply SC shown is wired in the same way, and includes a variable impedance circuit within the power transmission path. In all combinations, it is possible to achieve the following: Figure 9 The output from the first power supply SA is branched as shown, and sensors for measuring variable impedance circuits and self-bias or voltage waveforms can be configured. The fifth power supply SE can be connected to the auxiliary electrode AUX, either alone or in combination with any of the aforementioned power supply connections.

[0186] As described above, the plasma processing apparatus includes a chamber 10, a stage 16, an electrostatic chuck 18 (first lower electrode), and an auxiliary electrode AUX (second lower electrode). The plasma processing apparatus also includes a first electrode plate 36 (first upper electrode), second electrode plates 35, 35b (second upper electrodes), and a first power supply SA (SF). The stage 16 and electrostatic chuck 18 are disposed inside the chamber 10, having a substrate mounting area for mounting a semiconductor wafer W. The auxiliary electrode AUX is disposed in the peripheral region of the substrate. The first electrode plate 36 is disposed facing the substrate mounting area. The second electrode plates 35, 35b are disposed in the region outside the first electrode plate 36 and facing the auxiliary electrode AUX. The first power supply SA (SF) supplies a periodic signal to the stage 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 plates 35, 35b is located on the normal to the surface of the recess D.

[0187] Electrons accelerated from the vicinity of the recess D of one of the auxiliary electrode AUX and the second electrode plates 35, 35b toward the other are concentrated, thus increasing the plasma density in the peripheral region of the substrate and suppressing the increase in plasma density in the center of the substrate mounting region. Therefore, the in-plane uniformity of the plasma can be improved.

[0188] Furthermore, the configurations where only the lower surface of the second electrode plate 35 is a recess D, the configuration where only the upper surface of the auxiliary electrode AUX is a recess D, and the configuration where both are recesses can be applied to all embodiments. Additionally, as described above, the edge ring ER and the auxiliary electrode AUX can also be integrated.

[0189] The foregoing has described various exemplary embodiments, but is not limited to these exemplary embodiments; various omissions, substitutions, and modifications are possible. Furthermore, elements from different embodiments can be combined to form other embodiments. It should also be understood from the foregoing description that various embodiments of this disclosure have been described in this specification for illustrative purposes, and various modifications can be made without departing from the scope and spirit of this disclosure. Therefore, the various embodiments disclosed in this specification are not intended to limit the scope, and the true scope and spirit are indicated by the appended claims.

[0190] Explanation of reference numerals in the attached figures

[0191] 1: Plasma processing device; 10: Chamber; 10a: Grounding conductor; 14: Support platform; 16: Placement stage (first lower electrode); 18: Electrostatic chuck; 26: Insulating component; 34: Upper electrode; 35, 35b: Second electrode plate (second upper electrode); 36: First electrode plate (first upper electrode); 37: Ejection hole; 38: Electrode support; 39: Insulating component; 40: Gas diffusion chamber; 41: Gas flow hole; 42: Insulating shielding component; 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 device; 88: Second matching device; SA: Power supply; SB: Power supply; SC: Power supply; SD: Power supply; SE: Power supply; 95: Control unit; 96: User interface; 97: Storage unit; AUX: Auxiliary electrode (second lower electrode); ER: Edge ring; PL: Plasma; W: Semiconductor wafer; D: Recess.

Claims

1. A plasma processing device, comprising: Chamber; A first lower electrode is disposed inside the chamber and has a substrate mounting area for mounting a substrate. The second lower electrode is disposed in the region outside the substrate mounting area; The first upper electrode is disposed facing the substrate mounting area; A second upper electrode is disposed in a region outside the first upper electrode and is disposed facing the second lower electrode; and A first power source supplies a periodic signal to the first lower electrode. Both the second lower electrode and the second upper electrode have recesses. The recess of the second upper electrode is located on the normal line to the surface of the recess of the second lower electrode. Furthermore, the recess of the second lower electrode is located on the normal line of the surface of the recess of the second upper electrode. In this configuration, the recess of one of the second lower electrode and the second upper electrode is recessed in a direction away from the other. The plasma processing device also has: A fifth power source supplies a periodic signal to the second lower electrode; A sensor that measures the self-biased voltage or voltage waveform generated at the second lower electrode; and The control unit controls the output of the fifth power supply based on the measured values ​​obtained by the sensor.

2. The plasma processing apparatus according to claim 1, characterized in that, It also has a second power source that supplies DC voltage to the second upper electrode.

3. The plasma processing apparatus according to claim 1 or 2, characterized in that, It also has a third power source that supplies a periodic signal to the second upper electrode.

4. The plasma processing apparatus according to claim 3, characterized in that, It also has: A first power supply line is used to supply the first upper electrode with a periodic signal output from the third power supply; as well as A second power supply line is used to supply the second upper electrode with a periodic signal output from the third power supply. The first power supply line or the second power supply line has a variable impedance circuit.

5. The plasma processing apparatus according to claim 2, characterized in that, It also has a fourth power source, which supplies DC voltage to the second lower electrode.

6. The plasma processing apparatus according to claim 1 or 2, characterized in that, It also has: A third power supply line is used to supply the first lower electrode with a periodic signal output from the first power source; as well as A fourth power supply line is used to supply the second lower electrode with the periodic signal output from the first power supply. The third or fourth power supply line has a variable impedance circuit.

7. The plasma processing apparatus according to claim 4, characterized in that, The control unit also controls the impedance of the variable impedance circuit based on the measured values ​​obtained by the sensor.

8. The plasma processing apparatus according to claim 2, characterized in that, The control unit also controls the output of the second power supply based on the measured values ​​obtained by the sensor.

9. The plasma processing apparatus according to claim 8, characterized in that, The control unit controls the output of the second power supply so that the second upper electrode generates a negative DC voltage that is greater than or equal to the self-bias voltage generated by the second lower electrode.

10. The plasma processing apparatus according to claim 1 or 2, characterized in that, The second lower electrode and the second upper electrode are electrically grounded.

11. The plasma processing apparatus according to claim 1 or 2, characterized in that, The spacing between the second upper electrode and the second lower electrode is narrower than the spacing between the first upper electrode and the first lower electrode.

12. The plasma processing apparatus according to claim 1 or 2, characterized in that, A conductive edge ring is provided between the substrate mounting area for mounting the substrate and the second lower electrode.

13. The plasma processing apparatus according to claim 1 or 2, characterized in that, The second upper electrode and the second lower electrode are arranged such that the normal to the bottom surface of the recess is inclined relative to the normal to the substrate mounting area.

14. The plasma processing apparatus according to claim 13, characterized in that, The second upper electrode is formed by the inner wall of the chamber or a deposit shielding element disposed along the inner wall of the chamber.

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