Plasma processing apparatus and plasma processing method

Abstract

A plasma processing apparatus disclosed in the present invention has a direct current power source for generating a negative direct current voltage. A bias electrode of a substrate support provided in a chamber is alternately connected to the direct current power source and to ground. The time period during which the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground is set to be longer than the time period during which the potential of the bias electrode reaches the negative direct current voltage after the direct current power source is connected to the bias electrode.

Description

Technical Field

[0001] Exemplary embodiments of the present invention relate to a plasma processing apparatus and a plasma processing method. Background Technology

[0002] In plasma processing of a substrate, a plasma processing apparatus is used. The plasma processing apparatus includes a chamber and a substrate support. The substrate support has a lower electrode and an electrostatic chuck. The electrostatic chuck is disposed on the lower electrode. The substrate support supports an edge ring. The substrate is placed on the substrate support within the area surrounded by the edge ring. To introduce ions from the plasma into the substrate, a bias power is supplied to the lower electrode. Such a plasma processing apparatus is disclosed in Japanese Patent Application Publication No. 2019-36658. Summary of the Invention

[0003] This invention provides a technique for reducing the energy of ions directed toward the chamber walls of a plasma processing device.

[0004] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a plasma generation unit, a substrate support, a DC power supply, a first switch, an adjustment unit, and a control unit. The plasma generation unit is configured to generate plasma from gas within the chamber. The substrate support has a bias electrode and is disposed within the chamber. The DC power supply is configured to generate a negative DC voltage. The first switch is connected between the DC power supply and the bias electrode. The adjustment unit has at least one second switch connected between ground and the bias electrode. The control unit is configured to control the first switch and at least one second switch to alternately connect the DC power supply and ground to the bias electrode. The adjustment unit is configured such that the time until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to ground is longer than the time until the potential of the bias electrode reaches a negative DC voltage after the DC power supply is connected to the bias electrode.

[0005] According to an exemplary embodiment, the energy of ions directed toward the chamber wall of a plasma processing device can be reduced. Attached Figure Description

[0006] Figure 1 This is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment.

[0007] Figure 2 This is a diagram illustrating in detail the structure within the chamber of a plasma processing apparatus according to an exemplary embodiment.

[0008] Figure 3 This is a diagram illustrating an adjustment unit that can be used in a plasma processing apparatus according to an exemplary embodiment.

[0009] Figure 4 This is a diagram illustrating an example of the time-dependent change in the potential of a substrate.

[0010] Figure 5 This is a diagram illustrating an adjustment unit that can be used in a plasma processing apparatus according to an exemplary embodiment.

[0011] Figure 6 This is a diagram that schematically illustrates a plasma processing apparatus according to another exemplary embodiment.

[0012] Figure 7 This is a flowchart of a plasma processing method according to an exemplary embodiment. Detailed Implementation

[0013] The following describes various exemplary embodiments.

[0014] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a plasma generation unit, a substrate support, a DC power supply, a first switch, an adjustment unit, and a control unit. The plasma generation unit is configured to generate plasma from gas within the chamber. The substrate support has a bias electrode and is disposed within the chamber. The DC power supply is configured to generate a negative DC voltage. The first switch is connected between the DC power supply and the bias electrode. The adjustment unit has at least one second switch connected between ground and the bias electrode. The control unit is configured to control the first switch and at least one second switch to alternately connect the DC power supply and ground to the bias electrode. The adjustment unit is configured such that the time until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to ground is longer than the time until the potential of the bias electrode reaches a negative DC voltage after the DC power supply is connected to the bias electrode.

[0015] According to the above embodiment, since the time it takes for the bias electrode's potential to reach the ground potential after the bias electrode is connected to the ground is long, the amount of overshoot towards the positive side of the substrate potential after the bias electrode is connected to the ground is reduced. Therefore, the rise in plasma potential after the bias electrode is connected to the ground is suppressed. Consequently, the potential difference between the plasma and the chamber wall is reduced, and the energy of ions toward the chamber wall is reduced.

[0016] In one exemplary embodiment, the adjustment unit may further include a circuit element connected between the bias electrode and ground. The circuit element extends the time until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to ground. In one exemplary embodiment, the circuit element may include an inductor, a resistor, or a capacitor.

[0017] In one exemplary embodiment, the plasma processing apparatus may further include other circuit elements connected between the DC power supply and the bias electrode. In this embodiment, the circuit constant of the circuit element in the adjustment unit is greater than the circuit constant of the other circuit elements. In one exemplary embodiment, the other circuit elements may further include inductors, resistors, or capacitors.

[0018] In one exemplary embodiment, the control unit may be configured to control at least one second switch to intermittently connect the bias electrode to ground until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to ground.

[0019] In one exemplary embodiment, the adjustment unit may include a plurality of second switches, which are connected in parallel between the ground and the bias electrode as at least one second switch. The control unit is configured to intermittently and sequentially close the plurality of second switches until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground.

[0020] In one exemplary embodiment, the substrate support may further have a dielectric portion formed of a dielectric. A bias electrode may be disposed in the dielectric portion. In one exemplary embodiment, the dielectric portion may constitute an electrostatic chuck.

[0021] In one exemplary embodiment, the substrate support may have a first region on which a substrate is mounted and a second region on which an edge ring is mounted. A bias electrode is disposed in a dielectric portion in the first region. The substrate support may also have other bias electrodes. Other bias electrodes are disposed in a dielectric portion in the second region. The plasma processing apparatus may also include other DC power supplies, a third switch, and other adjustment units. The other DC power supply is configured to generate a negative DC voltage. The third switch is connected between the other DC power supply and other bias electrodes. The other adjustment unit has at least one fourth switch connected between ground and other bias electrodes. The control unit is configured to control the third switch and at least one fourth switch to alternately connect the other DC power supply and ground to the other bias electrodes. The time until the potential of the other bias electrode reaches the ground potential after the other adjustment unit connects the other bias electrode to ground is set to be longer than the time until the potential of the other bias electrode reaches a negative DC voltage after the other DC power supply is connected to the other bias electrode.

[0022] In one exemplary embodiment, the substrate support may have a lower electrode as a bias electrode and an electrostatic chuck disposed on the lower electrode.

[0023] In another exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a step (a) of preparing a substrate on a substrate support within a cavity of a plasma processing apparatus. The plasma processing method also includes a step (b) of generating plasma within the cavity. The plasma processing method includes a step (c) of alternately connecting a bias electrode of the substrate support to a DC power supply and ground. The DC power supply is configured to generate a negative DC voltage. In step (c), the time until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to ground is set to be longer than the time until the potential of the bias electrode reaches the negative DC voltage after the DC power supply is connected to the bias electrode.

[0024] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same or equivalent parts are labeled with the same symbols.

[0025] Figure 1 This is a diagram that roughly illustrates a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 1 includes a chamber 10. Figure 2 This is a diagram showing in detail the structure within the chamber of a plasma processing apparatus according to an exemplary embodiment. (As shown...) Figure 2 As shown, the plasma processing device 1 can be a capacitively coupled plasma processing device.

[0026] The chamber 10 provides an internal space 10s. The central axis of the internal space 10s is an axis AX extending in a vertical direction. In one embodiment, the chamber 10 includes a chamber body 12. The chamber body 12 has a generally cylindrical shape. The internal space 10s is disposed within the chamber body 12. The chamber body 12 is formed, for example, of aluminum. The chamber body 12 is electrically grounded. A plasma-resistant membrane is formed on the inner wall surface of the chamber body 12, i.e., on the wall surface dividing the internal space 10s. This membrane can be a ceramic membrane formed by anodizing or by yttrium oxide.

[0027] The sidewall of the chamber body 12 is provided with a passage 12p. When the substrate W is transported between the internal space 10s and the outside of the chamber 10, the substrate W passes through the passage 12p. A gate valve 12g is provided along the sidewall of the chamber body 12 for opening and closing the passage 12p.

[0028] The plasma processing apparatus 1 also includes a substrate support 16. The substrate support 16 is configured to support a substrate W placed on it within the chamber 10. The substrate W has a generally disc-shaped form. The substrate support 16 is supported by a support portion 17. The support portion 17 extends upward from the bottom of the chamber body 12. The support portion 17 has a generally cylindrical shape. The support portion 17 is formed of an insulating material such as quartz.

[0029] The substrate support 16 may have a base 18 and an electrostatic chuck 20. The base 18 and the electrostatic chuck 20 may be disposed in the chamber 10. The lower electrode 18 is formed of a conductive material such as aluminum and has a generally disc-shaped form.

[0030] The base 18 has a flow path 18f inside it. Flow path 18f is for a heat exchange medium. The heat exchange medium is, for example, a liquid refrigerant. Flow path 18f receives the heat exchange medium from a supply device (e.g., a cooling unit) located outside the chamber 10. The heat exchange medium flows through flow path 18f and returns to the supply device via piping 23b.

[0031] An electrostatic chuck 20 is disposed on a base 18. When a substrate W is processed in the internal space 10s, the substrate W is placed on and held by the electrostatic chuck 20. A substrate support 16 can support an edge ring ER mounted thereon. The edge ring ER is a plate having a generally ring shape. The edge ring ER may be conductive. The edge ring ER is formed, for example, from silicon or silicon carbide. The edge ring ER is mounted on the substrate support 16 with its central axis aligned with axis AX. The substrate W, housed within the chamber 10, is disposed on the electrostatic chuck 20 and within the area surrounded by the edge ring ER.

[0032] The plasma processing apparatus 1 may also provide a gas supply line 25. The gas supply line 25 supplies heat transfer gas, such as He gas, from the gas supply mechanism to the gap between the upper surface of the electrostatic chuck 20 (the first region described later) and the back surface (lower surface) of the substrate W.

[0033] The plasma processing apparatus 1 may also include an outer peripheral portion 28 and an outer peripheral portion 29. The outer peripheral portion 28 extends upward from the bottom of the chamber body 12. The outer peripheral portion 28 has a generally cylindrical shape and extends along the outer periphery of the support portion 17. The outer peripheral portion 28 is formed of a conductive material and has a generally cylindrical shape. The outer peripheral portion 28 is electrically grounded. A plasma-resistant film is formed on the surface of the outer peripheral portion 28. This film may be a ceramic film formed by anodizing or formed of yttrium oxide.

[0034] An outer peripheral portion 29 is disposed on an outer peripheral portion 28. The outer peripheral portion 29 is formed of an insulating material. For example, the outer peripheral portion 29 is formed of ceramic such as quartz. The outer peripheral portion 29 has a generally cylindrical shape. The outer peripheral portion 29 extends along the outer periphery of the base 18 and the electrostatic chuck 20.

[0035] The plasma processing apparatus 1 also includes an upper electrode 30. The upper electrode 30 is disposed above the substrate support 16. The upper electrode 30, together with the component 32, seals the upper opening of the chamber body 12. The component 32 is insulating. The upper electrode 30 is supported on the upper part of the chamber body 12 via the component 32.

[0036] The upper electrode 30 includes a top plate 34 and a support 36. The lower surface of the top plate 34 divides an internal space 10s. The top plate 34 provides a plurality of gas holes 34a. The plurality of gas holes 34a penetrate the top plate 34 along the thickness direction (vertical direction) and open toward the internal space 10s. The top plate 34 is formed, for example, of silicon. Alternatively, the top plate 34 may have a structure in which a plasma-resistant film is formed on the surface of an aluminum component. This film may be a ceramic film formed by anodizing or formed of yttrium oxide.

[0037] The support body 36 detachably supports the top plate 34. The support body 36 is formed of a conductive material, such as aluminum. The support body 36 provides a gas diffusion chamber 36a inside. The support body 36 also provides a plurality of gas holes 36b. The plurality of gas holes 36b extend downward from the gas diffusion chamber 36a. The plurality of gas holes 36b are respectively connected to the plurality of gas holes 34a. The support body 36 also provides a gas inlet port 36c. The gas inlet port 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas inlet port 36c.

[0038] A gas source group 40 is connected to the gas supply pipe 38 via a valve group 41, a flow controller group 42, and a valve group 43. The gas supply unit comprises the gas source group 40, valve group 41, flow controller group 42, and valve group 43. The gas source group 40 includes multiple gas sources. Valve groups 41 and 43 each include multiple valves (e.g., open and close valves). The flow controller group 42 includes multiple flow controllers. These flow controllers are either mass flow controllers or pressure-controlled flow controllers. The multiple gas sources of the gas source group 40 are connected to the gas supply pipe 38 via valves corresponding to valve group 41, flow controllers corresponding to flow controller group 42, and valves corresponding to valve group 43. The plasma processing apparatus 1 can supply gas from one or more selected gas sources from the multiple gas sources of the gas source group 40 at individually regulated flow rates to the internal space for 10 seconds.

[0039] The plasma processing apparatus 1 may also include a baffle component 48. The baffle 48 is disposed between the outer periphery 28 and the side wall of the chamber body 12. The baffle component 48 may be constructed, for example, by coating an aluminum component with a ceramic such as yttrium oxide. The baffle 48 provides multiple through holes. Below the baffle 48, an exhaust pipe 52 is connected to the bottom of the chamber body 12. An exhaust device 50 is connected to the exhaust pipe 52. The exhaust device 50 has a pressure controller such as an automatic pressure control valve and a vacuum pump such as a turbomolecular pump, which can reduce the pressure in the internal space for 10 seconds.

[0040] The substrate support 16 will now be described in detail. As described above, the substrate support 16 includes a base 18 and an electrostatic chuck 20. Figure 1As shown, a high-frequency power supply 61 is connected to the base 18 via an integrator 62. The base 18 constitutes the lower electrode. Alternatively, the high-frequency power supply 61 may not be electrically connected to the base 18, but may be connected to the upper electrode 30 via the integrator 62.

[0041] The high-frequency power supply 61 is a power source for generating high-frequency electricity for plasma generation. That is, the high-frequency power supply 61 constitutes the plasma generation unit in one embodiment. The high-frequency electricity generated by the high-frequency power supply 61 has a frequency in the range of 27 to 100 MHz, for example, 40 MHz or 60 MHz. The high-frequency electricity from the high-frequency power supply 61 is supplied to the base station 18 via the integrator 62. The high-frequency power supply 61 can supply a continuous wave of high-frequency electricity. Alternatively, the high-frequency power supply 61 can supply pulses of high-frequency electricity. The pulses of high-frequency electricity can be supplied more than once within the bias period described later. The integrator 62 has an integration circuit. The integration circuit of the integrator 62 has a variable impedance. The impedance adjustment of the integration circuit of the integrator 62 is to reduce the reflection of the load from the high-frequency power supply 61.

[0042] In the plasma processing apparatus 1, if high-frequency power is supplied from the high-frequency power supply 61, the gas in the chamber 10 is excited, and plasma is generated from the gas. The substrate W is processed by chemical species such as ions and / or free radicals from the generated plasma. For example, the substrate W is etched.

[0043] In one embodiment, the substrate support 16 has a dielectric portion 20d. The dielectric portion 20d is formed of a dielectric such as aluminum nitride or aluminum oxide. The dielectric portion 20d has a generally disc-shaped form. The dielectric portion 20d is disposed on the base 18. In one embodiment, the dielectric portion 20d constitutes an electrostatic chuck 20.

[0044] In one embodiment, the substrate support 16 has a first region 21 and a second region 22. The first region 21 and the second region 22 are provided by an electrostatic chuck 20. Figure 1 In the diagram, the boundary between region 1 (21) and region 22 is indicated by a dashed line. Alternatively, region 1 (21) and region 22 can also be separated from each other.

[0045] The first region 21 is configured to support a substrate W mounted thereon (i.e., on its upper surface). The first region 21 is a region having a disk shape. The central axis of the first region 21 is substantially aligned with axis aX. The first region 21 includes a portion (central portion) of the dielectric portion 20d. In one embodiment, the thickness of the dielectric portion 20d in the second region 22 may be less than the thickness of the dielectric portion 20d in the first region 21. The vertical position of the upper surface of the dielectric portion 20d in the second region 22 may be lower than the vertical position of the upper surface of the dielectric portion 20d in the first region 21.

[0046] The first region 21 has an electrode 21a (chuck electrode). Electrode 21a is a film-like electrode disposed within the dielectric portion 20d in the first region 21. A DC power supply 55 is connected to electrode 21a via a switch 56. Additionally, a filter for reducing or blocking high-frequency power can be connected between electrode 21a and the DC power supply 55, besides the switch 56. When a DC voltage from the DC power supply 55 is applied to electrode 21a, an electrostatic attraction is generated between the first region 21 and the substrate W. Through this electrostatic attraction, the substrate W is attracted to and held by the first region 21.

[0047] The first region 21 may also have an electrode 21c. The electrode 21c is a film-shaped electrode and is disposed in the dielectric portion 20d in the first region 21. The electrode 21c constitutes a bias electrode. In addition, the electrode 21a may extend in the vertical direction closer to the upper surface of the first region 21 than the electrode 21c.

[0048] The plasma processing apparatus 1 also includes a DC power supply 63. The DC power supply 63 is configured to generate a negative DC voltage and apply this negative DC voltage to the electrode 21c. The plasma processing apparatus 1 also includes a switch 64 (first switch). The switch 64 is connected between the DC power supply 63 and the electrode 21c. The plasma processing apparatus 1 may also include an adjustment unit 65 and a filter 66. The adjustment unit 65 and the filter 66 are connected between the DC power supply 63 and the electrode 21c. The adjustment unit 65 and the filter 66 may also be connected between the switch 64 and the electrode 21c.

[0049] The second region 22 is configured to surround the first region 21. The second region 22 is a generally annular region. The central axis of the second region 22 is approximately aligned with the axis aX. The second region 22 is configured to support an edge ring ER mounted thereon (i.e., on its upper surface). The second region 22 includes another portion (edge ​​portion) of the dielectric portion 20d.

[0050] The second region 22 has electrodes 22a and 22b. Electrodes 22a and 22b constitute a bipolar electrode. Electrodes 22a and 22b are both film-shaped electrodes. Electrodes 22a and 22b are disposed in the dielectric portion 20d in the second region 22.

[0051] A DC power supply 71 is connected to electrode 22a via switch 72 and filter 73. Filter 73 is an electrical filter that cuts off or reduces high-frequency power. Filter 73 prevents high-frequency power from flowing into DC power supply 71, or reduces the high-frequency power flowing into DC power supply 71.

[0052] A DC power supply 74 is connected to electrode 22b via switch 75 and filter 76. Filter 76 is an electrical filter that cuts off or reduces high-frequency power. Filter 76 prevents high-frequency power from flowing into DC power supply 74, or reduces the high-frequency power flowing into DC power supply 74.

[0053] DC power supplies 71 and 74 apply DC voltages to electrodes 22a and 22b, respectively. Furthermore, the set potentials of electrodes 22a and 22b can be any one of positive, negative, or 0V. For example, the potential of electrode 22a can be set to positive, and the potential of electrode 22b can be set to negative. Moreover, the potential difference between electrodes 22a and 22b can be formed using a single DC power supply, rather than two DC power supplies.

[0054] For example, if a potential difference is applied between electrodes 22a and 22b, an electrostatic attraction is generated between the second region 22 and the edge ring ER, and the second region 22 functions as a bipolar electrostatic chuck. Therefore, even without plasma generation, the second region 22 is able to hold the edge ring ER. The edge ring ER is attracted to the second region 22 by the generated electrostatic attraction and held by the second region 22.

[0055] The second region 22 may also have a gas conduit 22g. The gas conduit 22g is a gas conduit designed for supplying heat transfer gas, such as He gas, between the second region 22 and the edge ring ER. The gas conduit 22g is connected to the gas supply structure 90, which serves as the heat transfer gas source.

[0056] The second region 22 also has an electrode 22c. Electrode 22c is a film-shaped electrode and is disposed in the dielectric portion 20d in the second region 22. Electrode 22c constitutes other bias electrodes. In addition, electrodes 22a and 22b may extend in the vertical direction closer to the upper surface of the second region 22 than electrode 22c.

[0057] The plasma processing apparatus 1 also includes a DC power supply 83. The DC power supply 83 is configured to generate a negative DC voltage and apply this negative DC voltage to the electrode 22c. The plasma processing apparatus 1 also includes a switch 84 (a third switch). The switch 84 is connected between the DC power supply 83 and the electrode 22c. The plasma processing apparatus 1 may also include an adjustment unit 85 and a filter 86. The adjustment unit 85 and the filter 86 are connected between the DC power supply 83 and the electrode 22c. The adjustment unit 85 and the filter 86 may also be connected between the switch 84 and the electrode 22c.

[0058] like Figure 2As shown, in one embodiment, the plasma processing apparatus 1 further includes a control unit MC. The control unit MC can be a computer equipped with a processor, storage device, input device, display device, etc. The control unit MC controls each part of the plasma processing apparatus 1. Specifically, the control unit MC executes a control program stored in the storage device and controls each part of the plasma processing apparatus 1 based on process data stored in the storage device. Through the control of the control unit MC, the program specified by the process data is executed in the plasma processing apparatus 1. For example, the plasma processing methods of various embodiments described later are executed in the plasma processing apparatus 1.

[0059] The following is for reference. Figure 3 . Figure 3 This diagram illustrates an adjustment unit that can be used in a plasma processing apparatus according to an exemplary embodiment. Filter 66 is an electrical filter that cuts off or reduces the high-frequency power generated by the high-frequency power supply 61. Filter 66 prevents the high-frequency power generated by the high-frequency power supply 61 from flowing into the DC power supply 63, or reduces the high-frequency power flowing into the DC power supply 63. For example... Figure 3 As shown, filter 66 can be an LC filter or other types of filters.

[0060] The adjustment unit 67 includes a switch 67s (second switch) and a circuit element 67d. The switch 67s and circuit element 67d are connected in series between ground and electrode 21c (or filter 66). When plasma is generated within chamber 10, the control unit MC controls the switches 64 and 67s by alternately connecting the DC power supply 63 and ground to electrode 21c. Therefore, pulses of negative DC voltage are intermittently applied to electrode 21c. These pulses of negative DC voltage can be applied periodically to electrode 21c. The period (time interval) of applying the negative DC voltage pulses to electrode 21c, i.e., the frequency of the specified bias period, is, for example, a frequency of 1 kHz or higher and 27 MHz or lower.

[0061] The regulating unit 65 is connected between the DC power supply 63 and the electrode 21c. In one embodiment, the regulating unit 65 is connected between the switch 64 and the filter 66. The regulating unit 65 is configured to regulate the time until the potential of the electrode 21c reaches the negative DC voltage applied by the DC power supply 63 after the electrode 21c is connected to the DC power supply 63 (hereinafter referred to as "first time").

[0062] The regulating unit 65 includes circuit elements. These circuit elements can be inductors or resistors. When the circuit elements of the regulating unit 65 are inductors or resistors, they are connected between the switch 64 and the electrode 21c. Alternatively, the circuit elements of the regulating unit 65 can be capacitors. When the circuit elements of the regulating unit 65 are capacitors, they are connected between a node on the line connecting the switch 64 and the electrode 21c and ground.

[0063] To increase the energy of the ions supplied from the plasma to the substrate W, the first time can be set to a short time. Therefore, the circuit constants (inductance, resistance, or capacitance) of the circuit elements of the adjustment unit 65 can have values ​​smaller than the circuit constants of the circuit elements 67d of the adjustment unit 67. In addition, the adjustment unit 65 can have a circuit that includes two or more of the aforementioned inductors, resistive elements, and capacitors.

[0064] The adjustment unit 67 is configured such that the time until the potential of electrode 21c reaches the ground potential after electrode 21c is connected to the ground (hereinafter referred to as "the second time") is longer than the first time. Specifically, in order to extend the second time, circuit element 67d of the adjustment unit 67 is used.

[0065] Circuit element 67d can be an inductor. Circuit element 67d can also be a resistor. When circuit element 67d is an inductor or a resistor, it is connected between switch 67s and electrode 21c. Alternatively, circuit element 67d can also be a capacitor. When circuit element 67d is a capacitor, it is connected between a node on the line connecting switch 67s and electrode 21c and ground. The circuit constant (inductance, resistance, or capacitance) of circuit element 67d is set to a value greater than the circuit constant of the aforementioned circuit element in adjustment unit 65. Furthermore, adjustment unit 67 can replace a single circuit element, having a circuit that includes two or more of the aforementioned inductors, resistors, and capacitors.

[0066] Filter 86 is an electrical filter that cuts off or reduces the high-frequency power generated by high-frequency power supply 61. Filter 86 prevents the high-frequency power generated by high-frequency power supply 61 from flowing into DC power supply 83, or reduces the high-frequency power flowing into DC power supply 83. Filter 86 is as follows: Figure 3 As shown, it can be an LC filter or other types of filters.

[0067] The regulating unit 87 includes a switch 87s (the fourth switch) and a circuit element 87d. The switch 87s and circuit element 87d are connected in series between the ground and the electrode 22c (or the filter 86). When the switches 84 and 87s generate plasma within the chamber 10, the control unit MC controls the alternating connection of the DC power supply 83 and the ground to the electrode 22c. Therefore, pulses of negative DC voltage are intermittently applied to the electrode 22c. These pulses of negative DC voltage can be applied periodically to the electrode 22c. The frequency of the period (time interval) for applying the pulses of negative DC voltage to the electrode 22c is specified to be, for example, a frequency of 1 kHz or higher and 27 MHz or lower. Furthermore, the pulses of negative DC voltage applied to the electrode 22c can be synchronized with the pulses of negative DC voltage applied to the electrode 21c.

[0068] The regulating unit 85 is connected between the DC power supply 83 and the electrode 22c. In one embodiment, the regulating unit 85 is connected between the switch 84 and the filter 86. The regulating unit 85 is configured to regulate the time until the potential of the electrode 22c reaches the negative DC voltage applied by the DC power supply 83 after the electrode 22c is connected to the DC power supply 83 (hereinafter referred to as "the third time").

[0069] The regulating unit 85 includes circuit elements. These circuit elements can be inductors or resistors. When the circuit elements of the regulating unit 85 are inductors or resistors, they are connected between the switch 84 and the electrode 22c. Alternatively, the circuit elements of the regulating unit 85 can be capacitors. When the circuit elements of the regulating unit 85 are capacitors, they are connected between a node on the line connecting the switch 84 and the electrode 22c and ground.

[0070] The circuit constants (inductance, resistance, or capacitance) of the circuit elements in the adjustment unit 85 can be smaller than the circuit constants of the circuit elements 87d in the adjustment unit 87. Furthermore, the adjustment unit 85 can have a circuit that includes two or more of the aforementioned inductors, resistors, and capacitors.

[0071] The adjustment unit 87 is configured such that the time until the potential of electrode 22c reaches the ground potential after electrode 22c is connected to the ground (hereinafter referred to as "the fourth time") is longer than the third time. Specifically, in order to extend the fourth time, circuit element 87d of the adjustment unit 87 is used.

[0072] Circuit element 87d can be an inductor. Circuit element 87d can also be a resistor. When circuit element 87d is an inductor or a resistor, it is connected between switch 87s and electrode 22c. Alternatively, circuit element 87d can also be a capacitor. When circuit element 87d is a capacitor, it is connected between a node on the line connecting switch 87s and electrode 22c and ground.

[0073] The circuit constant (inductance, resistance, or capacitance) of circuit element 87d is set to a value greater than that of the circuit constant of the aforementioned circuit element in adjustment unit 85. Furthermore, adjustment unit 87 can replace a single circuit element and has a circuit that includes two or more of the aforementioned inductors, resistors, and capacitors.

[0074] The following is for reference. Figure 4 . Figure 4 This is a graph illustrating an example of the time-dependent change in the potential of a substrate. In Figure 4 In the diagram, the dashed and solid lines represent the time-varying potentials of the substrate W when the electrode 21c is alternately connected to the DC power supply 63 and grounded, respectively, within the plasma processing apparatus 1. Figure 4 In the diagram, the dashed line represents the time-varying potential of the substrate W when the circuit constant of circuit element 67d is the same as that of the circuit element of adjustment unit 65. Figure 4 In the diagram, the solid line represents the time-varying potential of the substrate W when the circuit constant of circuit element 67d is greater than the circuit constant of the circuit element of adjustment unit 65. Figure 4 In the diagram, t1 represents the moment when electrode 21c is connected to DC power supply 63, and t2 represents the moment when electrode 21c is connected to ground.

[0075] When the circuit constant of circuit element 67d is relatively small, that is, when the second time is relatively short, such as in Figure 4 As shown by the dotted line, the overshoot of electrode 21c to the positive side of the potential of the substrate W after grounding is relatively large. The plasma potential rises with the substrate potential, therefore, when the second time interval is relatively short, the potential difference between the plasma and the wall of chamber 10 increases. Consequently, when the second time interval is relatively short, the energy of the ions toward the wall of chamber 10 increases. As a result, the wall of chamber 10 or nearby components are damaged, and particles are released.

[0076] On the other hand, when the circuit constant of circuit element 67d is relatively large, i.e., when the second time is relatively long, such as in Figure 4As shown by the solid line, the amount of overshoot to the positive side of the potential of the substrate W after connecting to electrode 21c is reduced. As a result, the rise in potential of the plasma after electrode 21c is connected to ground is suppressed. Similarly, the rise in potential of the plasma after electrode 22c is connected to ground is suppressed. Therefore, the potential difference between the plasma and the wall of chamber 10 is reduced, and the energy of the ions toward the wall of chamber 10 is reduced.

[0077] Furthermore, in the plasma processing apparatus 1, since the time from when the DC power supply 63 is connected to the electrode 21c until the potential of the electrode 21c reaches the negative DC voltage is short, higher energy ions are supplied to the substrate W.

[0078] The following is for reference. Figure 5 . Figure 5 This diagram illustrates an adjustment unit that can be used in a plasma processing apparatus according to an exemplary embodiment. In plasma processing apparatus 1, the adjustment unit that can be used... Figure 5 The adjustment section 67 and adjustment section 87 are shown.

[0079] Figure 5 The adjustment unit 67 shown has a plurality of switches 67s1, 67s2 (a plurality of second switches). The plurality of switches 67s1, 67s2 are connected in parallel between the ground and the electrode 21c. In one embodiment, the plurality of switches 67s1, 67s2 are connected in parallel between the filter 66 and the ground.

[0080] like Figure 5 As shown, the adjustment unit 67 may also have multiple circuit elements 67d1 and 67d2. These multiple circuit elements 67d1 and 67d2 are connected in series with multiple switches 67s1 and 67s2, respectively. The multiple circuit elements 67d1 and 67d2 can be either inductors or resistors. When the multiple circuit elements 67d1 and 67d2 are either inductors or resistors, they are connected between the corresponding switch (switch 67s1 or switch 67s2) and the electrode 21c. Alternatively, the multiple circuit elements 67d1 and 67d2 can be capacitors. When the multiple circuit elements 67d1 and 67d2 are capacitors, they are connected between a node on the line connecting the corresponding switch (switch 67s1 or switch 67s2) and the electrode 21c and ground.

[0081] The circuit constants of each of the multiple circuit elements 67d1 and 67d2 can be the same as, or greater than, the circuit constants of the circuit elements in the adjustment unit 65. Furthermore, the number of switches and the number of circuit elements in the adjustment unit 67 can each be greater than two. Moreover, instead of a single circuit element 67d1, the adjustment unit 67 can also have a circuit including two or more of the aforementioned inductors, resistors, and capacitors. Similarly, instead of a single circuit element 67d2, the adjustment unit 67 can also have a circuit including two or more of the aforementioned inductors, resistors, and capacitors.

[0082] When using Figure 5 In the case of the adjustment unit 67 shown, when plasma is generated in the chamber 10, the control unit MC controls the switch 64 and multiple switches 67s1 and 67s2 by alternately connecting the DC power supply 63 and ground to the electrode 21c. When using Figure 5 In the case of the adjustment unit 67 shown, the control unit MC controls multiple switches 67s1 and 67s2 by intermittently connecting electrode 21c to ground until the potential of electrode 21c reaches the ground potential. In one embodiment, the control unit MC controls multiple switches 67s1 and 67s2 by intermittently and sequentially closing multiple switches 67s1 and 67s2 until the potential of electrode 21c reaches the ground potential after connecting electrode 21c to ground.

[0083] Figure 5 The adjustment unit 87 shown has a plurality of switches 87s1 and 87s2. The plurality of switches 87s1 and 87s2 are connected in parallel between the ground and the electrode 22c. In one embodiment, the plurality of switches 87s1 and 87s2 are connected in parallel between the filter 86 and the ground.

[0084] like Figure 5 As shown, the adjustment unit 87 may also have multiple circuit elements 87d1 and 87d2. These multiple circuit elements 87d1 and 87d2 are connected in series with multiple switches 87s1 and 87s2, respectively. The multiple circuit elements 87d1 and 87d2 can be either inductors or resistors. When the multiple circuit elements 87d1 and 87d2 are either inductors or resistors, they are connected between the corresponding switch (switch 87s1 or switch 87s2) and the electrode 22c. Alternatively, the multiple circuit elements 87d1 and 87d2 can be capacitors. When the multiple circuit elements 87d1 and 87d2 are capacitors, they are connected between a node on the line connecting the corresponding switch (switch 87s1 or switch 87s2) and the electrode 22c and ground.

[0085] The circuit constants of each of the multiple circuit elements 87d1 and 87d2 can be the same as, or greater than, the circuit constants of the circuit elements in the regulating unit 85. Furthermore, the number of switches and the number of circuit elements in the regulating unit 87 can each be greater than two. Moreover, instead of a single circuit element 87d1, the regulating unit 87 can also have a circuit including two or more of the aforementioned inductors, resistors, and capacitors. Similarly, instead of a single circuit element 87d2, the regulating unit 87 can also have a circuit including two or more of the aforementioned inductors, resistors, and capacitors.

[0086] When using Figure 5 In the case of the adjustment unit 87 shown, when plasma is generated in the chamber 10, the control unit MC controls the switch 84 and multiple switches 87s1 and 87s2 by alternately connecting the DC power supply 83 and ground to the electrode 22c. When using Figure 5 In the case of the adjustment unit 87 shown, the control unit MC controls multiple switches 87s1 and 87s2 by intermittently connecting electrode 22c to ground until the potential of electrode 22c reaches the ground potential. In one embodiment, the control unit MC controls multiple switches 87s1 and 87s2 by intermittently and sequentially closing multiple switches 87s1 and 87s2 until the potential of electrode 22c reaches the ground potential after connecting electrode 22c to ground.

[0087] When using Figure 5 In the case of the adjustment unit 67 shown, the time it takes for the potential of electrode 21c to reach the ground potential after electrode 21c is connected to ground is longer. Therefore, the amount of overshoot towards the positive side of the potential of the substrate W after electrode 21c is connected to ground is reduced. As a result, the rise in the potential of the plasma after electrode 21c is connected to ground is suppressed. Similarly, the rise in the potential of the plasma after electrode 22c is connected to ground is suppressed. Therefore, the potential difference between the plasma potential and the wall of chamber 10 is reduced, and the energy of the ions toward the wall of chamber 10 is reduced.

[0088] Furthermore, the regulating unit 67 may have a single switch instead of multiple switches 67s1 and 67s2. The control unit MC may control the single switch by intermittently closing the single switch until the potential of electrode 21c reaches the ground potential after electrode 21c is connected to ground. Also, the regulating unit 87 may have a single switch instead of multiple switches 87s1 and 87s2. The control unit MC may control the single switch by intermittently closing the single switch until the potential of electrode 22c reaches the ground potential after electrode 22c is connected to ground.

[0089] The following is for reference. Figure 6 . Figure 6This is a diagram that schematically illustrates a plasma processing apparatus according to another exemplary embodiment. Figure 6 The plasma processing apparatus 1b shown does not include a DC power supply 83, a switch 84, an adjustment unit 85, a filter 86, or an adjustment unit 87. In the plasma processing apparatus 1b, the base 18 constitutes a bias electrode. That is, the DC power supply 63 is connected to the base 18 via the switch 64, the adjustment unit 65, and the filter 66. The base 18, filter 66, and adjustment unit 67 are connected to ground. The other structures of the plasma processing apparatus 1b can be the same as the corresponding structure of the plasma processing apparatus 1.

[0090] The following is for reference. Figure 7 . Figure 7 This is a flowchart of a plasma processing method according to an exemplary embodiment. Figure 7 The plasma processing method shown (hereinafter referred to as "method MT") can be performed using plasma processing apparatus 1 or 1B.

[0091] In step ST1 of method MT, a substrate is prepared on a substrate support of the plasma processing apparatus. When using plasma processing apparatus 1 or 1B, the substrate W is placed on the substrate support 16. The substrate W can be held by an electrostatic chuck 20.

[0092] In process ST2, plasma is generated from gas in the chamber. When plasma processing device 1 or 1B is used, gas from the gas supply unit is supplied into the chamber 10, the pressure in the chamber 10 is reduced by the exhaust device 50, and high-frequency power is supplied from the high-frequency power supply 61.

[0093] Step ST3 is performed while plasma is generated within the chamber. In step ST3, the bias electrodes of the substrate support are alternately connected to a DC power supply and ground. When using plasma processing apparatus 1, electrode 21c is alternately connected to DC power supply 63 and ground, and electrode 22c is alternately connected to DC power supply 83 and ground. When using plasma processing apparatus 1B, base 18 is alternately connected to DC power supply 63 and ground.

[0094] In process ST3, the time it takes for the potential of the bias electrode to reach the ground potential after the bias electrode is connected to ground is longer than the time it takes for the potential of the bias electrode to reach a negative DC voltage after the DC power supply is connected to the bias electrode. When using plasma processing apparatus 1 or 1B, the time it takes for the potential of electrode 21c or base 18 to reach the ground potential after the electrode 21c or base 18 is grounded is longer than the time it takes for the potential of electrode 21c or base 18 to reach a negative DC voltage after the DC power supply 63 is connected to the electrode 21c or base 18. Therefore, an adjustment unit 67 is used in plasma processing apparatus 1 or 1B. Furthermore, when using plasma processing apparatus 1, the time it takes for the potential of electrode 22c to reach the ground potential after the electrode 22c is connected to ground is longer than the time it takes for the potential of electrode 22c to reach a negative DC voltage after the DC power supply 83 is connected to the electrode 22c. Therefore, an adjustment unit 87 is used in plasma processing apparatus 1.

[0095] The above descriptions have illustrated various exemplary embodiments, but the embodiments are not limited to these exemplary embodiments. Various additions, omissions, substitutions, and modifications can be made. Furthermore, elements from different embodiments can be combined to form other embodiments.

[0096] For example, in other embodiments, the plasma processing apparatus may be a capacitively coupled plasma processing apparatus other than plasma processing apparatus 1 and plasma processing apparatus 1b. In yet another embodiment, the plasma processing apparatus may be of a type other than capacitively coupled plasma processing apparatus. Such a plasma processing apparatus may be an inductively coupled plasma processing apparatus, an electron cyclotron resonance (ECR) plasma processing apparatus, or a plasma processing apparatus that generates plasma from surface waves such as microwaves.

[0097] Furthermore, the plasma processing device 1 may not include circuit element 67d, and switch 67s may be connected to electrode 21c via circuit element of adjustment unit 65. The plasma processing device 1 may not include circuit element 87d, and switch 87s may be connected to electrode 22c via circuit element of adjustment unit 85.

[0098] Furthermore, switch 64, adjustment unit 65, and adjustment unit 67 can be included in DC power supply 63. Also, switch 84, adjustment unit 85, and adjustment unit 87 can be included in DC power supply 83. Furthermore, DC power supply 63 and DC power supply 83 can each be configured to generate the same small electrical waveform, amplify the generated waveform using an amplifier, and apply it to the corresponding electrode. The waveforms generated by DC power supply 63 and DC power supply 83 can be sawtooth-shaped waveforms, triangular waveforms, or pulse waveforms, rather than rectangular waves. DC power supply 63 and DC power supply 83 can each be a pulse power supply that applies a negative voltage.

[0099] As can be understood from the above description, various embodiments of the present invention have been described in this specification for illustrative purposes, and various modifications can be made without departing from the scope and spirit of the invention. Therefore, the embodiments disclosed in this specification are not intended to be limiting, and the true scope and spirit are indicated by the scope of the appended claims.

Claims

1. A plasma processing apparatus, comprising: Chamber; The plasma generation unit is configured to generate plasma from gas within the chamber; A substrate support having a bias electrode and disposed within the cavity; A DC power supply configured to generate a negative DC voltage; The first switch is connected between the DC power supply and the bias electrode; The adjustment section has at least one second switch connected between the ground and the bias electrode; and The control unit is configured to control the first switch and the at least one second switch to alternately connect the DC power supply and the ground to the bias electrode. The adjustment unit is configured such that the time until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground is longer than the time until the potential of the bias electrode reaches the negative DC voltage after the DC power supply is connected to the bias electrode.

2. The plasma processing apparatus according to claim 1, wherein, The adjustment unit further includes: a circuit element connected between the bias electrode and the ground, which extends the time until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground.

3. The plasma processing apparatus according to claim 2, wherein, The circuit elements include inductors, resistors, or capacitors.

4. The plasma processing apparatus according to claim 2 or 3, further comprising: Other circuit components are connected between the DC power supply and the bias electrode. The circuit constant of the circuit element in the adjustment section is greater than the circuit constant of the other circuit elements.

5. The plasma processing apparatus according to claim 4, wherein, The other circuit elements include inductors, resistors, or capacitors.

6. The plasma processing apparatus according to claim 1, wherein, The control unit is configured to control the at least one second switch to intermittently connect the bias electrode to the ground until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground.

7. The plasma processing apparatus according to claim 6, wherein, The adjustment unit includes: a plurality of second switches, which, as the at least one second switch, are connected in parallel between the ground and the bias electrode. The control unit is configured to intermittently and sequentially close the plurality of second switches until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground.

8. The plasma processing apparatus according to claim 1, wherein... The substrate support further includes: a dielectric portion formed of a dielectric material. The bias electrode is disposed in the dielectric portion.

9. The plasma processing apparatus according to claim 8, wherein, The dielectric section constitutes an electrostatic chuck.

10. The plasma processing apparatus according to claim 8, wherein, The substrate support has a first region on which a substrate is mounted and a second region on which an edge ring is mounted. The bias electrode is disposed in the dielectric portion in the first region. The substrate support also has other bias electrodes disposed in the dielectric portion in the second region. The plasma processing device also includes: Other DC power supplies are configured to generate negative DC voltage; A third switch is connected between the other DC power supply and the other bias electrodes; and Other adjustment units have at least one fourth switch connected between the ground and the other bias electrodes. The control unit is configured to control the third switch and the at least one fourth switch to alternately connect the other DC power supply and the ground to the other bias electrodes. The other adjustment unit is configured such that the time until the potential of the other bias electrode reaches the ground potential after the other bias electrode is connected to the ground is longer than the time until the potential of the other bias electrode reaches the negative DC voltage after the other DC power supply is connected to the other bias electrode.

11. The plasma processing apparatus according to claim 1, wherein, The substrate support has a lower electrode that serves as the bias electrode and an electrostatic chuck disposed on the lower electrode.

12. A plasma processing method, comprising: (a) The process of preparing a substrate on a substrate support within the chamber of a plasma processing apparatus; (b) The process of generating plasma within the chamber; and (c) The process of alternately connecting the bias electrodes of the substrate support to a DC power supply and ground, wherein the DC power supply is configured to generate a negative DC voltage. In (c), the time until the potential of the bias electrode reaches the ground potential after the bias electrode is connected to the ground is set to be longer than the time until the potential of the bias electrode reaches the negative DC voltage after the DC power supply is connected to the bias electrode.

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