Plasma processing apparatus and plasma processing method

Abstract

The plasma processing apparatus of the present application has a plasma processing chamber, a substrate support, a bias power supply, and a high-frequency power supply. The substrate support is disposed in the plasma processing chamber and includes an electrode. The bias power supply is combined with the electrode and configured to generate bias power having a first frequency. The high-frequency power supply is combined with the plasma processing chamber and configured to generate high-frequency power having a second frequency higher than the first frequency. The high-frequency power has a first power level during a first period within one cycle of the bias power and a second power level lower than the first power level during a second period within one cycle of the bias power.

Description

TECHNICAL FIELD

[0001] An exemplary embodiment of the present application relates to a plasma processing apparatus and a plasma processing method. BACKGROUND

[0002] A plasma processing apparatus is used for processing of a substrate. A plasma processing apparatus has a chamber, a stage, a first high-frequency power source, and a second high-frequency power source. The stage is configured to support the substrate in the chamber. The stage includes a lower electrode. The first high-frequency power source is configured to generate high-frequency power for generating plasma from a gas in the chamber. The second high-frequency power source is configured to generate high-frequency bias power for attracting ions from the plasma to the substrate. The high-frequency bias power is supplied to the lower electrode. Japanese Patent Application Publication No. 2016-157735 discloses a plasma processing apparatus configured to supply at least one of the high-frequency power and the high-frequency bias power as pulsed power. SUMMARY

[0003] The present application provides a technique for improving uniformity of a radial density distribution of plasma and suppressing reduction or disappearance of a density of the plasma.

[0004] In an exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus has a plasma processing chamber, a substrate support, a bias power source, and a high-frequency power source. The substrate support is disposed in the plasma processing chamber and includes an electrode. The bias power source is associated with the electrode and configured to generate bias power having a first frequency. The high-frequency power source is associated with the plasma processing chamber and configured to generate high-frequency power having a second frequency higher than the first frequency. The high-frequency power has a first power level during a first period in one cycle of the bias power and a second power level lower than the first power level during a second period in the one cycle of the bias power.

[0005] According to an exemplary embodiment, it is possible to improve uniformity of a radial density distribution of plasma and suppress reduction or disappearance of a density of the plasma. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment.

[0007] Figure 2 FIG. 4 is a timing chart of an example of high-frequency power and electric bias used in the plasma processing apparatus according to an exemplary embodiment.

[0008] Figure 3 FIG. 5 is a timing chart of another example of high-frequency power and electric bias used in the plasma processing apparatus according to an exemplary embodiment.

[0009] Figure 4 is a timing chart of another example of an electric bias used in a plasma processing apparatus according to an example embodiment.

[0010] Figure 5 is a diagram schematically showing a plasma processing apparatus according to another example embodiment.

[0011] Figure 6 is a diagram showing an example of an edge ring that can be used in a plasma processing apparatus shown in Figure 5

[0012] Figure 7 is a diagram showing another example of an edge ring.

[0013] Figure 8 is a flowchart of a plasma processing method according to an example embodiment. DETAILED DESCRIPTION

[0014] Hereinafter, various example embodiments will be described.

[0015] In an example embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a plasma processing chamber, a substrate support, a bias power supply, and a high frequency (RF; Radio Frequency) power supply. The substrate support is disposed in the plasma processing chamber and includes a lower electrode. The bias power supply is coupled to the lower electrode and configured to generate a bias power having a first frequency. The high frequency power supply is coupled to the plasma processing chamber and configured to generate a high frequency power having a second frequency higher than the first frequency. In an embodiment, the high frequency power supply is coupled to at least one of two opposing electrodes, such as a lower electrode and an upper electrode. The high frequency power has a first power level during a first period within one cycle of the bias power and a second power level lower than the first power level during a second period within the one cycle of the bias power. The one cycle of the bias power is a natural cycle defined by the first frequency. That is, the natural cycle is the inverse of the first frequency. For example, when the first frequency is 400 kHz, the natural cycle is 2.5 μs. The first period is different from the second period. The second period can precede the first period or follow the first period.

[0016] ​In one example embodiment, the bias power includes at least one bias pulse in one period. The at least one bias pulse can have a pulse waveform of a rectangle, a trapezoid, a triangle, or a combination thereof, or can have a shaped pulse (also referred to as a tailored pulse) as disclosed in US2018 / 0166249A1. The at least one bias pulse has a positive polarity or a negative polarity. Also, the at least one bias pulse can include a plurality of bias pulses having a positive polarity and / or a negative polarity. In one embodiment, the bias power includes at least one positive bias pulse and at least one negative bias pulse in one period.

[0017] In one example embodiment, the bias power is a high-frequency bias power having a first frequency. In one embodiment, the bias power source is configured to continuously generate the high-frequency bias power. At this time, the high-frequency bias power does not include an off period.

[0018] In another example embodiment, a plasma processing apparatus is provided. The plasma processing apparatus has a chamber, a substrate support, a bias power source, and a high-frequency power source. The substrate support includes a lower electrode configured to support a substrate in the chamber. The bias power source is configured to generate an electric bias for attracting ions to the substrate and is electrically connected to the lower electrode. The electric bias varies a potential of the substrate in a period defined by a first frequency. The high-frequency power source is configured to generate a high-frequency power having a second frequency for generating a plasma from a gas in the chamber. The high-frequency power source is configured to supply a first pulse of the high-frequency power in a first period and a second pulse of the high-frequency power in a second period. The first period at least partially overlaps with the period defined by the first frequency and has a time length shorter than a time length of the period. The second period at least partially overlaps with the period defined by the first frequency and has a time length shorter than the time length of the period. The second pulse has a power level lower than a power level of the first pulse.

[0019] In a case where the high-frequency power is continuously supplied, i.e., in a case of a continuous wave of the high-frequency power, a density of the plasma in the chamber is high in the center and is low in a radial outer side. In the above-described embodiment, the high-frequency power is supplied as the first pulse. Therefore, according to the above-described embodiment, uniformity of a radial density distribution of the plasma is high. Also, in the above-described embodiment, after the first pulse is supplied, the second pulse of the high-frequency power having a relatively low power is supplied. Therefore, according to the above-described embodiment, a decrease or disappearance of the density of the plasma can be suppressed.

[0020] In one example embodiment, the electric bias can be a pulse wave periodically generated with a period defined by a first frequency. The pulse wave includes a pulse of a negative direct current voltage.

[0021] In one example embodiment, the first period and the second period can each be a period within a period defined by the first frequency in which a pulse of the negative DC voltage from the bias power supply is not supplied. According to this embodiment, reflection of each of the first pulse and the second pulse is reduced.

[0022] In one example embodiment, the high-frequency power supply can be configured to supply, in a period between the first period and the second period, high-frequency power having a power level lower than the power level of the first pulse and the power level of the second pulse and greater than 0 W.

[0023] In one example embodiment, the first period can overlap with a period in which a pulse of the negative DC voltage from the bias power supply is supplied. The second period can be a period within a period in which a pulse of the negative DC voltage from the bias power supply is not supplied.

[0024] In one example embodiment, the high-frequency power supply can also be configured to supply, in a period between the second period and an end time of the period defined by the first frequency, high-frequency power. The high-frequency power supplied in the period between the second period and the end time of the period has a power level lower than the power level of the first pulse and the power level of the second pulse and greater than 0 W.

[0025] In one example embodiment, the electric bias can be high-frequency bias power having the first frequency.

[0026] In one example embodiment, the plasma processing apparatus can further have a matcher connected between the bias power supply and the lower electrode. The first pulse and the second pulse can also be supplied when an impedance of a load with respect to the bias power supply is in a substantially matched state.

[0027] In yet another example embodiment, a plasma processing method is provided. The plasma processing method includes a process of preparing a substrate on a substrate support provided in a chamber of a plasma processing apparatus. The plasma processing apparatus has a bias power supply and a high-frequency power supply. The bias power supply is configured to generate an electric bias that varies a potential of the substrate in a period defined by a first frequency. The high-frequency power supply is configured to generate high-frequency power having a second frequency. The plasma processing method includes a process of supplying the electric bias from the bias power supply to a lower electrode of the substrate support. The plasma processing method also includes a process of supplying, from the high-frequency power supply, a first pulse of the high-frequency power in a first period. The first period at least partially overlaps with the period defined by the first frequency and has a time length shorter than a time length of the period. The plasma processing method also includes a process of supplying, from the high-frequency power supply, a second pulse of the high-frequency power in a second period within the period defined by the first frequency. The second period at least partially overlaps with the period defined by the first frequency and has a time length shorter than the time length of the period. The second pulse has a power level lower than a power level of the first pulse.

[0028] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In addition, in the drawings, the same or equivalent portions are denoted by the same symbols.

[0029] Figure 1 is a view schematically showing a plasma processing apparatus according to an exemplary embodiment. Figure 1 The plasma processing apparatus 1 shown is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 1 is provided with a plasma processing chamber 10. An internal space 10s is provided in the chamber 10. A central axis of the internal space 10s is an axis AX extending in the vertical direction. In an embodiment, the chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The internal space 10s is provided in the chamber body 12. The chamber body 12 is made of, for example, aluminum. The chamber body 12 is electrically grounded. A film having plasma resistance is formed on an inner wall surface of the chamber body 12, that is, a wall surface that divides the internal space 10s. The film can be a film formed by an anodization treatment or a ceramic film such as a film formed of yttrium oxide.

[0030] A passage 12p is formed in a side wall of the chamber body 12. When a substrate W is carried 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 side wall of the chamber body 12 for opening and closing of the passage 12p.

[0031] The plasma processing apparatus 1 is also provided with a substrate support 16. The substrate support 16 is configured to support a substrate W placed thereon in the chamber 10. The substrate W has a substantially disc shape. The substrate support 16 is supported by a support portion 17. The support portion 17 extends upward from a bottom of the chamber body 12. The support portion 17 has a substantially cylindrical shape. The support portion 17 is formed of an insulating material such as quartz.

[0032] The substrate support 16 has a lower electrode 18 and an electrostatic chuck 20. The lower electrode 18 and the electrostatic chuck 20 are provided in the chamber 10. The lower electrode 18 is formed of an electrically conductive material such as aluminum and has a substantially disc shape.

[0033] A flow path 18f is formed in the lower electrode 18. The flow path 18f is a flow path for a heat exchange medium. As the heat exchange medium, a refrigerant in a liquid state or a refrigerant (for example, chlorofluorocarbon) that cools the lower electrode 18 by gasification thereof is used. A supply device (for example, a cooling unit) of the heat exchange medium is connected to the flow path 18f. The supply device is provided outside the chamber 10. The heat exchange medium is supplied from the supply device to the flow path 18f via a pipe 23a. The heat exchange medium supplied to the flow path 18f is returned to the supply device via a pipe 23b.

[0034] The electrostatic chuck 20 is provided on the lower electrode 18. When the substrate W is processed in the internal space 10s, the substrate W is placed on the electrostatic chuck 20 and held by the electrostatic chuck 20.

[0035] The electrostatic chuck 20 has a main body and an electrode. The main body of the electrostatic chuck 20 is formed of a dielectric such as alumina or aluminum nitride. The main body of the electrostatic chuck 20 has a substantially disc shape. The central axis of the electrostatic chuck 20 substantially coincides with the axis AX. The electrode of the electrostatic chuck 20 is provided in the main body. The electrode of the electrostatic chuck 20 has a film shape. A direct-current power source is electrically connected to the electrode of the electrostatic chuck 20 via a switch. When a voltage from the direct-current power source is applied to the electrode of the electrostatic chuck 20, electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. The substrate W is attracted to the electrostatic chuck 20 and held by the electrostatic chuck 20 by the generated electrostatic attraction.

[0036] The electrostatic chuck 20 includes a substrate placement region. The substrate placement region is a region having a substantially disc shape. The central axis of the substrate placement region substantially coincides with the axis AX. The substrate W is placed on the upper surface of the substrate placement region when processed in the chamber 10.

[0037] In one embodiment, the electrostatic chuck 20 can further include an edge ring placement region. The edge ring placement region extends in the circumferential direction in a manner of surrounding the substrate placement region about the central axis of the electrostatic chuck 20. The edge ring ER is mounted on the upper surface of the edge ring placement region. The edge ring ER has a ring shape. The edge ring ER is placed on the edge ring placement region in a manner in which the central axis thereof coincides with the axis AX. The substrate W is disposed in a region surrounded by the edge ring ER. That is, the edge ring ER is disposed so as to surround the edge of the substrate W. The edge ring ER can have electrical conductivity. The edge ring ER is formed of, for example, silicon or silicon carbide. The edge ring ER can be formed of a dielectric such as quartz.

[0038] The plasma processing apparatus 1 can further be provided with a gas supply line 25. The gas supply line 25 supplies a heat transfer gas such as He gas from a gas supply mechanism to a gap between the upper surface of the electrostatic chuck 20 and the back surface (lower surface) of the substrate W.

[0039] The plasma processing apparatus 1 can further be provided with an insulating region 27. The insulating region 27 is disposed on the support portion 17. The insulating region 27 is disposed on the outer side of the lower electrode 18 in the radial direction with respect to the axis AX. The insulating region 27 extends in the circumferential direction along the outer peripheral surface of the lower electrode 18. The insulating region 27 is formed of an insulator such as quartz. The edge ring ER is placed on the insulating region 27 and the edge ring placement region.

[0040] The plasma processing apparatus 1 further includes an upper electrode 30. The upper electrode 30 is disposed above the substrate support 16. That is, the upper electrode 30 is disposed above the lower electrode 18. The upper electrode 30 closes the upper opening of the chamber main body 12 together with a member 32. The member 32 is insulative. The upper electrode 30 is supported to the upper portion of the chamber main body 12 via the member 32.

[0041] The upper electrode 30 includes a top plate 34 and a support body 36. A lower surface of the top plate 34 divides the internal space 10s. A plurality of exhaust holes 34a are formed in the top plate 34. The plurality of exhaust holes 34a respectively penetrate the top plate 34 in a plate thickness direction (a vertical direction). The top plate 34 is not limited, and is formed of silicon, for example. Alternatively, the top plate 34 can have a structure in which a film having plasma resistance is provided on a surface of an aluminum member. The film can be a film formed by an anodization treatment or a ceramic film formed of yttrium oxide.

[0042] The support body 36 detachably supports the top plate 34. The support body 36 is formed of an electrically conductive material such as aluminum, for example. A gas diffusion chamber 36a is provided in the inside of the support body 36. A plurality of gas holes 36b extend downward from the gas diffusion chamber 36a. The plurality of gas holes 36b respectively communicate with the plurality of exhaust holes 34a. A gas introduction port 36c is formed in the support body 36. The gas introduction port 36c is connected to the gas diffusion chamber 36a. A gas supply pipe 38 is connected to the gas introduction port 36c.

[0043] A gas source group 40 is connected to the gas supply pipe 38 via a valve group 41, a flow rate controller group 42, and a valve group 43. A gas supply portion is constituted by the gas source group 40, the valve group 41, the flow rate controller group 42, and the valve group 43. The gas source group 40 includes a plurality of gas sources. The valve group 41 and the valve group 43 each include a plurality of valves (e.g., on-off valves). The flow rate controller group 42 includes a plurality of flow rate controllers. The plurality of flow rate controllers of the flow rate controller group 42 are each a mass flow controller or a pressure control type flow rate controller. The plurality of gas sources of the gas source group 40 are each connected to the gas supply pipe 38 via a valve corresponding to the valve group 41, a flow rate controller corresponding to the flow rate controller group 42, and a valve corresponding to the valve group 43. The plasma processing apparatus 1 can supply a gas from one or more gas sources selected from the plurality of gas sources of the gas source group 40 to the internal space 10s at a flow rate individually adjusted.

[0044] A baffle 48 is provided between the substrate support 16 or the support portion 17 and the side wall of the chamber main body 12. The baffle 48 can be formed by, for example, coating a ceramic such as yttria on an aluminum member. A plurality of through-holes are formed in the baffle 48. A gas exhaust pipe 52 is connected to the bottom of the chamber main body 12 below the baffle 48. An exhaust device 50 is connected to the gas 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 turbo molecular pump, and can reduce the pressure of the internal space 10s.

[0045] The plasma processing apparatus 1 further has a high-frequency power source 61. The high-frequency power source 61 is a power source that generates high-frequency electric power RF. The high-frequency electric power RF is used to generate plasma from a gas in the chamber 10. The high-frequency electric power RF has a second frequency. The second frequency is a frequency in a range of 13 to 200 MHz, for example, a frequency of 40 MHz or 60 MHz. In order to supply the high-frequency electric power RF to the lower electrode 18, the high-frequency power source 61 is connected to the lower electrode 18 via a matching circuit 63. The matching circuit 63 is configured to match the impedance of the load side (lower electrode 18 side) of the high-frequency power source 61 to the output impedance of the high-frequency power source 61. In addition, the high-frequency power source 61 can not be electrically connected to the lower electrode 18, but can be connected to the upper electrode 30 via the matching circuit 63.

[0046] The plasma processing apparatus 1 further has a bias power source 62. The bias power source 62 is connected to the lower electrode 18 via a circuit 64. The bias power source 62 generates an electric bias (bias electric power) EB. The electric bias EB is used to attract ions to the substrate W. The electric bias EB is set to vary the potential of the substrate W placed on the electrostatic chuck 20 within a period CP defined by a first frequency. The period CP is the inverse of the first frequency. The first frequency can be a frequency lower than the second frequency. The first frequency is, for example, a frequency of 50 kHz or more and 27 MHz or less.

[0047] Figure 2 A timing chart of an example of the high-frequency electric power and the electric bias used in the plasma processing apparatus according to one example embodiment. Figure 3 A timing chart of another example of the high-frequency electric power and the electric bias used in the plasma processing apparatus according to one example embodiment. In one embodiment, as Figure 2 or Figure 3As shown, the pulse wave PLW is used as the electric bias EB. In the case where the pulse wave PLW is used as the electric bias EB, the circuit 64 includes a filter circuit that blocks or reduces the high-frequency electric power RF. The pulse wave PLW is periodically applied to the lower electrode 18 with a pulse period CP. The pulse wave PLW includes at least one bias pulse. In one embodiment, the pulse wave PLW includes a negative direct-current voltage pulse NPL. The pulse NPL is also periodically applied to the lower electrode 18 with the period CP. The pulse NPL is applied to the lower electrode 18 for a period PA within the period CP. The voltage level of the pulse wave PLW can be 0 V for a period PB other than the period PA within the period CP. Alternatively, the voltage level of the pulse wave PLW can have an absolute value that is smaller than the absolute value of the voltage of the pulse NPL for the period PB. Also, the voltage level of the pulse wave PLW can have a positive value that is smaller than the value of the voltage of the pulse NPL for the period PB. In addition, the start timing and the length of the period CP, the voltage level of the pulse wave PLW, and the proportion of the period PA within the period CP (i.e., the duty ratio) can be specified in the bias power supply 62 by a control signal from the control section MC.

[0048] When plasma etching is performed in the plasma processing apparatus 1, a gas is supplied to the internal space 10s. Then, by supplying the high-frequency electric power RF, the gas is excited in the internal space 10s. Also, by the electric bias EB applied to the lower electrode 18, ions from the plasma are attracted to the substrate W. Then, the substrate W is processed by chemical species such as ions and / or radicals from the plasma. For example, plasma etching of the substrate W is performed.

[0049] In the plasma processing apparatus 1, as shown in Figure 2 or Figure 3 As shown, the high-frequency power supply 61 supplies a first pulse RFP1 of the high-frequency electric power RF for a first period P1. The first period P1 has a length shorter than the length of the period CP and at least partially overlaps with the period CP. Also, the high-frequency power supply 61 supplies a second pulse RFP2 of the high-frequency electric power RF for a second period P2. The second period P2 is a period different from the first period P1. The second period P2 has a length shorter than the length of the period CP and at least partially overlaps with the period CP. The power level of the second pulse RFP2 (second power level) is lower than the power level of the first pulse RFP1 (first power level). The first period P1 and the second period P2 and the power level of the high-frequency electric power RF can be specified in the high-frequency power supply 61 by a control signal from the control section MC. The power level of the high-frequency electric power RF that can be specified in the high-frequency power supply 61 includes the power level of the first pulse RFP1 and the power level of the second pulse RFP2.

[0050] In one embodiment, as shown in Figure 2As shown, the first period P1 and the second period P2 are periods within a period CP in which the pulse NPL is not supplied (i.e., a period PB). In the period PB, the thickness of the sheath (plasma sheath) becomes thin, and the impedance becomes small. Therefore, the reflection of each of the first pulse RFP1 and the second pulse RFP2 is suppressed. In this embodiment, as shown in FIG. 6, the high-frequency power source 61 can be configured to supply the high-frequency power RF in a third period P3 between the first period P1 and the second period P2. The power level of the high-frequency power RF supplied in the period P3 between the period P1 and the period P2 can have a third power level lower than the power level of the first pulse RFP1 and the power level of the second pulse RFP2 and greater than 0 W. In addition, in this embodiment, the power level of the high-frequency power RF in the period PA can be 0 W. Alternatively, the power level of the high-frequency power RF in the period PA can be greater than 0 W and lower than the power level of the first pulse, the power level of the second pulse, and the power level of the high-frequency power RF in the period P3. Figure 2 As shown, the first period P1 and the second period P2 are periods within a period CP in which the pulse NPL is not supplied (i.e., a period PB). In the period PB, the thickness of the sheath (plasma sheath) becomes thin, and the impedance becomes small. Therefore, the reflection of each of the first pulse RFP1 and the second pulse RFP2 is suppressed. In this embodiment, as shown in FIG. 6, the high-frequency power source 61 can be configured to supply the high-frequency power RF in a third period P3 between the first period P1 and the second period P2. The power level of the high-frequency power RF supplied in the period P3 between the period P1 and the period P2 can have a third power level lower than the power level of the first pulse RFP1 and the power level of the second pulse RFP2 and greater than 0 W. In addition, in this embodiment, the power level of the high-frequency power RF in the period PA can be 0 W. Alternatively, the power level of the high-frequency power RF in the period PA can be greater than 0 W and lower than the power level of the first pulse, the power level of the second pulse, and the power level of the high-frequency power RF in the period P3.

[0051] In one embodiment, as shown in FIG. 5, the first period P1 and the second period P2 are periods within a period CP in which the pulse NPL is not supplied (i.e., a period PB). In the period PB, the thickness of the sheath (plasma sheath) becomes thin, and the impedance becomes small. Therefore, the reflection of each of the first pulse RFP1 and the second pulse RFP2 is suppressed. In this embodiment, as shown in FIG. 6, the high-frequency power source 61 can be configured to supply the high-frequency power RF in a third period P3 between the first period P1 and the second period P2. The power level of the high-frequency power RF supplied in the period P3 between the period P1 and the period P2 can have a third power level lower than the power level of the first pulse RFP1 and the power level of the second pulse RFP2 and greater than 0 W. In addition, in this embodiment, the power level of the high-frequency power RF in the period PA can be 0 W. Alternatively, the power level of the high-frequency power RF in the period PA can be greater than 0 W and lower than the power level of the first pulse, the power level of the second pulse, and the power level of the high-frequency power RF in the period P3. Figure 3 Figure 3 In one embodiment, as shown in FIG. 5, the first period P1 and the second period P2 are periods within a period CP in which the pulse NPL is not supplied (i.e., a period PB). In the period PB, the thickness of the sheath (plasma sheath) becomes thin, and the impedance becomes small. Therefore, the reflection of each of the first pulse RFP1 and the second pulse RFP2 is suppressed. In this embodiment, as shown in FIG. 6, the high-frequency power source 61 can be configured to supply the high-frequency power RF in a third period P3 between the first period P1 and the second period P2. The power level of the high-frequency power RF supplied in the period P3 between the period P1 and the period P2 can have a third power level lower than the power level of the first pulse RFP1 and the power level of the second pulse RFP2 and greater than 0 W. In addition, in this embodiment, the power level of the high-frequency power RF in the period PA can be 0 W. Alternatively, the power level of the high-frequency power RF in the period PA can be greater than 0 W and lower than the power level of the first pulse, the power level of the second pulse, and the power level of the high-frequency power RF in the period P3.

[0052] In one embodiment, as shown in FIG. 5, the first period P1 and the second period P2 are periods within a period CP in which the pulse NPL is not supplied (i.e., a period PB). In the period PB, the thickness of the sheath (plasma sheath) becomes thin, and the impedance becomes small. Therefore, the reflection of each of the first pulse RFP1 and the second pulse RFP2 is suppressed. In this embodiment, as shown in FIG. 6, the high-frequency power source 61 can be configured to supply the high-frequency power RF in a third period P3 between the first period P1 and the second period P2. The power level of the high-frequency power RF supplied in the period P3 between the period P1 and the period P2 can have a third power level lower than the power level of the first pulse RFP1 and the power level of the second pulse RFP2 and greater than 0 W. In addition, in this embodiment, the power level of the high-frequency power RF in the period PA can be 0 W. Alternatively, the power level of the high-frequency power RF in the period PA can be greater than 0 W and lower than the power level of the first pulse, the power level of the second pulse, and the power level of the high-frequency power RF in the period P3. Figure 1

[0053] ​​In one embodiment, the sheath regulator 74 is a power source configured to apply a voltage V N to the edge ring ER. The voltage V N may be a negative voltage. In addition, the voltage V N may also be a voltage having the same waveform as the electric bias EB. In this embodiment, the sheath regulator 74 is connected to the edge ring ER via a filter 75 and a lead 76. The filter 75 is a filter for blocking or reducing high-frequency power flowing into the sheath regulator 74.

[0054] The level of the voltage V N determines the amount of adjustment of the upper end position of the sheath above the edge ring ER. The amount of adjustment of the upper end position of the sheath above the edge ring ER, i.e., the level of the voltage V N is determined in accordance with a parameter indicative of the thickness of the edge ring ER. The parameter can be a measured value of the thickness of the edge ring ER optically or electrically measured, a position of the upper surface of the edge ring ER in the vertical direction optically or electrically measured, or a length of time during which the edge ring ER is exposed to the plasma. The level of the voltage V N is determined using a prescribed relationship between the parameter and the level of the voltage V N . For example, a prescribed relationship between the parameter and the level of the voltage V N is determined in advance such that the absolute value of the voltage V N increases if the thickness of the edge ring ER decreases. The relationship is stored as data in the form of a function or a table in a storage device of a control section MC described later. The level of the voltage V N is determined by the control section MC and specified to the sheath regulator 74. When the voltage V N having the determined level is applied to the edge ring ER by the sheath regulator 74, the difference between the upper end position of the sheath above the edge ring ER and the upper end position of the sheath above the substrate W is eliminated or reduced.

[0055] In addition, the voltage applied to the edge ring ER by the sheath regulator 74 can be a direct-current voltage or a high-frequency voltage. The voltage applied to the edge ring ER can also be a voltage having the same waveform as the electric bias EB. The voltage applied to the edge ring ER by the sheath regulator 74 can also be a pulsed high-frequency voltage or a pulsed direct-current voltage. That is, the voltage V N may be periodically applied to the edge ring ER. The voltage V N may be applied to the edge ring ER, for example, during the period PA within the cycle CP or a period overlapping the period PA. When a pulsed direct-current voltage is periodically applied to the edge ring ER as the voltage V N , the level of the voltage V N may be changed during the period in which the voltage V N is applied to the edge ring ER.

[0056] The control section MC is a computer provided with a processor, a storage device, an input device, a display device, and the like, and controls each section of the plasma processing apparatus 1. The control section MC executes a control program stored in the storage device, and controls each section of the plasma processing apparatus 1 according to process data stored in the storage device. A process specified by the process data is executed in the plasma processing apparatus 1 by control based on the control section MC. The plasma processing method according to the exemplary embodiments described later can be executed in the plasma processing apparatus 1 by control of each section of the plasma processing apparatus 1 based on the control section MC.

[0057] In a case where the high-frequency power RF is continuously supplied, that is, in a case of a continuous wave of the high-frequency power RF, the density of the plasma in the chamber 10 becomes high in the center (that is, a position on the axis AX and its vicinity) and low on the radially outer side. In the plasma processing apparatus 1, the high-frequency power RF is supplied as the first pulse RFP1. Therefore, according to the plasma processing apparatus 1, the uniformity of the radial density distribution of the plasma becomes high. Also, in the plasma processing apparatus 1, after the first pulse RFP1 is supplied, the second pulse RFP2 of the high-frequency power RF having a relatively low power is supplied. Therefore, according to the plasma processing apparatus 1, it is possible to suppress a decrease or disappearance of the density of the plasma.

[0058] Hereinafter, reference will be made to Figure 4 . Figure 4 is a timing chart of another example of the electric bias used in the plasma processing apparatus according to one exemplary embodiment. As shown in Figure 4 , the bias power supply 62 of the plasma processing apparatus 1 can also supply a high-frequency (RF) bias power as the electric bias EB to the lower electrode 18. The high-frequency bias power has the above-described first frequency. In this embodiment, the circuit 64 is a matching circuit configured to match the impedance of the load side (the lower electrode 18 side) of the bias power supply 62 to the output impedance of the bias power supply 62.

[0059] In a case where the high-frequency bias power is used as the electric bias EB, the first pulse RFP1 and the second pulse RFP2 can be supplied, respectively, when the impedance of the load of the bias power supply 62 is in a substantially matched state. That is, the first period P1 and the second period P2 can overlap, respectively, with a period in which the impedance of the load of the bias power supply 62 is in a substantially matched state with respect to the output impedance of the bias power supply 62 within the cycle CP. In addition, the load of the bias power supply 62 includes the plasma generated in the chamber 10.

[0060] Hereinafter, reference will be made to Figure 5 and Figure 6 . Figure 5 is a diagram schematically showing a plasma processing apparatus according to another exemplary embodiment. Figure 6is indicated that the plasma processing device is capable of Figure 5 A drawing of an example of an edge ring used in the plasma processing device shown. Figure 5 The plasma processing device 1B is different from the plasma processing device 1 in that an edge ring ERB is used instead of the edge ring ER. Also, the plasma processing device 1B is different from the plasma processing device 1 in that a sheath adjuster 74B is provided instead of the sheath adjuster 74. In other respects, the structure of the plasma processing device 1B can be the same as that of the plasma processing device 1.

[0061] As shown in FIG. 1, the edge ring ER is provided on the edge ring placement region. The edge ring ER is provided on the edge ring placement region so as to surround the edge of the substrate W. The edge ring ER is provided on the edge ring placement region so as to surround the edge of the substrate W. The edge ring ER is provided on the edge ring placement region so as to surround the edge of the substrate W. The edge ring ER is provided on the edge ring placement region so as to surround the edge of the substrate W. Figure 6 As shown in FIG. 1, the edge ring ER is provided on the edge ring placement region. The edge ring ER is provided on the edge ring placement region so as to surround the edge of the substrate W. The edge ring ER is provided on the edge ring placement region so as to surround the edge of the substrate W. The edge ring ER is provided on the edge ring placement region so as to surround the edge of the substrate W. The edge ring ER is provided on the edge ring placement region so as to surround the edge of the substrate W.

[0062] The sheath adjuster 74B is configured to move the second annular portion ER2 upward in order to adjust the position of the upper surface of the second annular portion ER2 in the vertical direction. In an example, the sheath adjuster 74B includes a driving device 74a and a shaft 74b. The shaft 74b supports the second annular portion ER2 and extends downward from the second annular portion ER2. The driving device 74a is configured to generate a driving force for moving the second annular portion ER2 along the vertical direction via the shaft 74b.

[0063] The sheath adjuster 74B is configured to adjust the amount of adjustment of the upper end position of the sheath above the edge ring ERB, i.e., the position of the upper surface of the second annular portion ER2 in the vertical direction, in order to correct the traveling direction of ions from the plasma to be perpendicular to the edge of the substrate W. The sheath adjuster 74B moves the second annular portion ER2 along the vertical direction so that the position of the upper surface of the second annular portion ER2 in the vertical direction coincides with the position of the upper surface of the substrate W on the electrostatic chuck 20 in the vertical direction.

[0064] The amount of adjustment of the upper end position of the sheath above the edge ring ERB, i.e., the amount of movement of the 2nd annular portion ER2, is determined in accordance with a parameter that reflects the thickness of the edge ring ERB, i.e., the thickness of the 2nd annular portion ER2. The parameter can be a measured value of the thickness of the 2nd annular portion ER2 that is optically or electrically measured, a position of the upper surface of the 2nd annular portion ER2 in the vertical direction that is optically or electrically measured, or a length of time for which the edge ring ERB is exposed to the plasma. The amount of movement of the 2nd annular portion ER2 is determined using a prescribed relationship between the parameter and the amount of movement of the 2nd annular portion ER2. For example, a prescribed relationship between the parameter and the amount of movement of the 2nd annular portion ER2 is determined in advance so that the amount of movement of the 2nd annular portion ER2 increases if the thickness of the 2nd annular portion ER2 decreases. When the 2nd annular portion ER2 is moved upward only by the determined amount of movement, the difference between the upper end position of the sheath on the edge ring ERB and the upper end position of the sheath above the substrate W is eliminated or reduced.

[0065] In the plasma processing apparatus IB, as described above, the control section MC can determine the amount of movement of the 2nd annular portion ER2. The prescribed relationship between the parameter and the amount of movement of the 2nd annular portion ER2 can be saved in the storage device of the control section MC as data in the form of a function or a table. The control section MC can control the sheath adjuster 74B so that the 2nd annular portion ER2 is moved upward by the determined amount of movement.

[0066] Figure 7 is a drawing showing another example of an edge ring. Figure 7 In the edge ring ERB shown, the 1st annular portion ERI has an inner peripheral portion and an outer peripheral portion. The position of the upper surface of the inner peripheral portion in the vertical direction is lower than the position of the upper surface of the outer peripheral portion in the vertical direction. The substrate W is placed on the substrate placement region with its edge located on the inner peripheral portion of the 1st annular portion ERI. The 2nd annular portion ER2 is disposed on the inner peripheral portion of the 1st annular portion ERI so as to surround the edge of the substrate W. That is, in the edge ring ERB shown, the 2nd annular portion ER2 is disposed on the inner peripheral portion of the 1st annular portion ERI. Figure 7 In the edge ring ERB shown, the 2nd annular portion ER2 is disposed inside the outer peripheral portion of the 1st annular portion ERI. In the edge ring ERB shown, the 2nd annular portion ER2 is disposed on the inner peripheral portion of the 1st annular portion ERI. Figure 7 In the case of the edge ring ERB shown, the shaft 74b of the sheath adjuster 74B can reach the lower surface of the 2nd annular portion ER2 through the through-hole formed in the inner peripheral portion of the 1st annular portion ERI.

[0067] Hereinafter, reference will be made to Figure 8 . Figure 8 is a flowchart of a plasma processing method according to an example embodiment. Figure 8 The plasma processing method shown (hereinafter, referred to as "method MT") is performed using any one of the plasma processing apparatuses according to the various embodiments described above, such as the plasma processing apparatus 1, the plasma processing apparatus IB, and the like.

[0068] The method MT starts in the step ST1. In the step ST1, the substrate W is prepared in the chamber 10. In the chamber 10, the substrate W is placed on the electrostatic chuck 20. The steps ST2, ST3 and ST4 of the method MT are executed in a state where the substrate W is placed on the electrostatic chuck 20. In the method MT, the gas is supplied from the gas supply portion to the chamber 10. Then, the pressure in the chamber 10 is set to a prescribed pressure by the exhaust device 50.

[0069] In the step ST2, the electric bias EB is supplied to the lower electrode 18. In the step ST3, the first pulse RFP1 of the high-frequency power RF is supplied for the first period P1. In the step ST4, the second pulse RFP2 of the high-frequency power RF is supplied for the second period P2.

[0070] In the step ST5, it is determined whether or not the end condition is satisfied. In a case where the number of repetitions of the cycle CP reaches a prescribed number of times, the end condition is satisfied. When it is determined in the step ST5 that the end condition is not satisfied, the steps ST2, ST3 and ST4 are executed again. On the other hand, when it is determined in the step ST5 that the end condition is satisfied, the execution of the method MT is ended.

[0071] The above describes various exemplary embodiments, but is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions and changes can be made. Also, elements in different embodiments can be combined to form other embodiments.

[0072] In another embodiment, the plasma processing apparatus can also be an inductively coupled plasma processing apparatus, an ECR (electron cyclotron resonance) plasma processing apparatus, a plasma processing apparatus that generates plasma using a surface wave such as a microwave.

[0073] From the above description, it is understood that the embodiments of the present application are described in the specification for the purpose of illustration, and various changes can be made without departing from the scope and spirit of the present application. Therefore, the embodiments disclosed in the specification are not intended to be limiting, and the true scope and spirit can be shown by the scope of the appended claims.

Claims

1. A plasma processing apparatus comprising: a plasma processing chamber; a substrate support disposed in the plasma processing chamber and including an electrode; a bias power source coupled to the electrode and configured to generate an electric bias having a first voltage level during a first period of a cycle, a second voltage level during a second period of the cycle and after the second period, and a third period, the absolute value of the first voltage level being greater than the absolute value of the second voltage level; and a high frequency power source coupled to the plasma processing chamber and configured to generate a high frequency power having a first power level during the first period of the cycle, a second power level during the second period of the cycle, a third power level during the third period of the cycle, and a fourth power level during a fourth period between the second period and the third period of the cycle, the second power level being greater than the third power level, the third power level being greater than the first power level, and the fourth power level being a level between the first power level and the third power level.

2. The plasma processing apparatus according to claim 1, wherein the electric bias has a pulse waveform that is rectangular, trapezoidal, triangular, or a combination thereof.

3. The plasma processing apparatus according to claim 1, wherein the electric bias has a shaped pulse.

4. The plasma processing apparatus according to any one of claims 1 to 3, wherein the first voltage level has a negative polarity.

5. The plasma processing apparatus according to any one of claims 1 to 3, wherein the second voltage level is a zero voltage level.

6. The plasma processing apparatus according to any one of claims 1 to 3, wherein the first power level is a zero power level.

7. A plasma processing method for use in a plasma processing apparatus having a plasma processing chamber, a substrate support disposed in the plasma processing chamber and including a lower electrode, and an upper electrode disposed above the lower electrode, the plasma processing method comprising: a process of placing a substrate on the substrate support; a process of supplying an electric bias to the lower electrode, the electric bias having a first voltage level during a first period of a cycle, a second voltage level during a second period of the cycle and after the second period, and a third period, the absolute value of the first voltage level being greater than the absolute value of the second voltage level; and ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ a step of supplying high-frequency electric power to the upper electrode or the lower electrode, the high-frequency electric power having a first power level in the first period of the one cycle, a second power level in the second period of the one cycle, a third power level in the third period of the one cycle, and a fourth power level in a fourth period between the second period and the third period of the one cycle, the second power level being greater than the third power level, the third power level being greater than the first power level, and the fourth power level being a level between the first power level and the third power level.

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