Plasma processing apparatus

Abstract

In a plasma processing apparatus according to an exemplary embodiment, a high-frequency power source generates high-frequency power supplied to generate plasma. The bias power supply supplies bias power to the lower electrode of the substrate support. The bias power varies the potential of the substrate during the period. The high-frequency power is supplied during at least a part of a first period in a period in which the potential of the substrate is relatively high. The power level of the high-frequency power decreases during a second period in a period in which the potential of the substrate is relatively low. During the first period and the second period, the sheath adjuster adjusts the position of the upper end of the sheath above the edge ring in the vertical direction.

Description

[0001] This application is a divisional application of an application with a filing date of December 26, 2019, application number 201911364552.X, and invention name “Plasma processing device and etching method”. Technical Field

[0002] An exemplary embodiment of the present invention relates to a plasma processing apparatus. Background Art

[0003] In plasma etching of a substrate, a plasma processing device is used. The plasma processing device includes a chamber, an electrostatic chuck, and a lower electrode. The electrostatic chuck and the lower electrode are arranged in the chamber. The electrostatic chuck is arranged on the lower electrode. The electrostatic chuck supports a focusing ring placed thereon. The electrostatic chuck supports a substrate arranged in an area surrounded by the focusing ring. When etching is performed in the plasma processing device, gas is supplied into the chamber. In addition, high-frequency power is supplied to the lower electrode. Plasma is formed by the gas in the chamber. The substrate is etched by chemical species such as ions and free radicals from the plasma.

[0004] When plasma etching is performed, the focus ring is consumed and the thickness of the focus ring is reduced. When the thickness of the focus ring is reduced, the position of the upper end of the plasma sheath (hereinafter referred to as "sheath") above the focus ring becomes lower. The position of the upper end of the sheath above the focus ring in the vertical direction should be equal to the position of the upper end of the sheath above the substrate in the vertical direction. Therefore, Japanese Patent Publication No. 2007-258417 and Japanese Patent Publication No. 2010-283028 describe plasma processing devices that can adjust the position of the upper end of the sheath above the focus ring in the vertical direction. The plasma processing devices described in these documents are configured to apply a DC voltage to the focus ring. Summary of the invention

[0005] The present invention provides a technology for adjusting the position of the upper end of a sheath above an edge ring in the vertical direction and reducing the difference between the etching rate at the edge of a substrate and the etching rate of the substrate further inside the edge.

[0006] In an exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a sheath regulator, a high-frequency power supply, a bias power supply, and a control unit. The substrate support has a lower electrode and an electrostatic chuck. The electrostatic chuck is disposed on the lower electrode. The substrate support is configured to support a substrate placed thereon in the chamber. The sheath regulator is configured to adjust the position of the upper end of the sheath above the edge ring in the vertical direction. The edge ring is configured to surround the edge of the substrate. The high-frequency power supply is configured to generate high-frequency power supplied to generate plasma from gas in the chamber. The high-frequency power has a first frequency. The bias power supply is configured to generate bias power. The bias power supply is electrically connected to the lower electrode. The bias power is set to change the potential of the substrate placed on the electrostatic chuck within a period specified by a second frequency. The second frequency is lower than the first frequency. The control unit is configured to control the sheath regulator and the high-frequency power supply. The control unit controls the high-frequency power supply so that the high-frequency power is supplied during at least a portion of the first period within the period. During the first period, the potential of the substrate placed on the electrostatic chuck is higher than the average value of the potential of the substrate in the cycle. The control unit controls the high-frequency power source so that the power level of the high-frequency power during the second period in the cycle is reduced compared to the power level of the high-frequency power during the first period. During the second period, the potential of the substrate placed on the electrostatic chuck is lower than the average value of the potential of the substrate in the cycle. The control unit controls the sheath adjuster in the first period and the second period to adjust the position of the upper end of the sheath in the vertical direction.

[0007] According to an exemplary embodiment, the position of the upper end of the sheath above the edge ring in the vertical direction can be adjusted, and the difference between the etching rate at the edge of the substrate and the etching rate of the substrate inside the edge can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment.

[0009] Figure 2 FIG. 1 is a timing chart showing high frequency power and bias power used in a plasma processing apparatus according to an exemplary embodiment.

[0010] Figure 3 (a) is a diagram showing an example of the vertical position of the upper end of the sheath in a state where the edge ring is consumed, Figure 3 (b) is a diagram showing an example of the corrected position of the upper end of the sheath in the vertical direction.

[0011] Figure 4 FIG. 1 is a timing chart showing high frequency power and bias power used in a plasma processing apparatus according to another exemplary embodiment.

[0012] Figure 5This is a diagram schematically showing a plasma processing apparatus according to still another embodiment.

[0013] Figure 6 (a) is a diagram showing an example of the vertical position of the upper end of the sheath in a state where the edge ring is consumed, Figure 6 (b) is a diagram showing an example of the corrected position of the upper end of the sheath in the vertical direction.

[0014] Figure 7 This is a diagram showing another example of an edge ring.

[0015] Figure 8 is a flow chart showing an etching method according to an exemplary embodiment. DETAILED DESCRIPTION

[0016] Various exemplary embodiments are described below.

[0017] In an exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a sheath regulator, a high-frequency power supply, a bias power supply, and a control unit. The substrate support has a lower electrode and an electrostatic chuck. The electrostatic chuck is disposed on the lower electrode. The substrate support is configured to support a substrate placed thereon in the chamber. The sheath regulator is configured to adjust the position of the upper end of the sheath above the edge ring in the vertical direction. The edge ring is configured to surround the edge of the substrate. The high-frequency power supply is configured to be a high-frequency power supplied to generate plasma from gas in the chamber. The high-frequency power has a first frequency. The bias power supply is configured to generate a bias power. The bias power supply is electrically connected to the lower electrode. The bias power is set to change the potential of the substrate placed on the electrostatic chuck within a period specified by a second frequency. The second frequency is lower than the first frequency. The control unit is configured to control the sheath regulator and the high-frequency power supply. The control unit controls the high-frequency power supply so that the high-frequency power is supplied during at least a portion of the first period within the period. During the first period, the potential of the substrate placed on the electrostatic chuck is higher than the average value of the potential of the substrate in the cycle. The control unit controls the high-frequency power source so that the power level of the high-frequency power during the second period in the cycle is reduced compared to the power level of the high-frequency power during the first period. During the second period, the potential of the substrate placed on the electrostatic chuck is lower than the average value of the potential of the substrate in the cycle. The control unit controls the sheath adjuster in the first period and the second period to adjust the position of the upper end of the sheath in the vertical direction.

[0018] When the position of the upper end of the sheath in the vertical direction is adjusted by the sheath adjuster, the impedance of the path of the high-frequency power reaching the plasma via the edge ring becomes larger. As a result, the power level of the high-frequency power supplied to the edge ring is reduced, and the power level of the high-frequency power supplied to the substrate is relatively increased. Therefore, a difference is generated between the etching rate at the edge of the substrate and the etching rate of the substrate further inside than the edge. In the above-mentioned embodiment, the high-frequency power is supplied during at least a part of the first period within the cycle of the bias power. During the first period, the potential difference between the substrate and the plasma is small, and the etching of the substrate proceeds relatively slowly, or the etching of the substrate is not substantially performed. On the other hand, during the second period, the potential difference between the substrate and the plasma is large, and the etching of the substrate is performed, but the power level of the high-frequency power is set to a low level or zero. Therefore, according to the above-mentioned embodiment, even if the position of the upper end of the sheath in the vertical direction is adjusted by the sheath adjuster, the difference between the etching rate at the edge of the substrate and the etching rate of the substrate further inside than the edge becomes smaller.

[0019] In an exemplary embodiment, the control unit may control the high-frequency power supply so as to stop supplying the high-frequency power during the second period.

[0020] In an exemplary embodiment, the sheath adjuster may be configured to apply a voltage to the edge ring in order to adjust the position of the upper end of the sheath in the vertical direction.

[0021] In an exemplary embodiment, the sheath adjuster may be configured to move the edge ring upward in order to adjust the position of the upper end of the sheath in the vertical direction.

[0022] In an exemplary embodiment, the bias power supply may be configured to supply a high-frequency bias power having a second frequency as the bias power to the lower electrode.

[0023] In an exemplary embodiment, the first period may be a period during which the high-frequency bias power output from the bias power supply has a positive potential, and the second period may be a period during which the high-frequency bias power output from the bias power supply has a negative potential.

[0024] In an exemplary embodiment, the bias power supply may be configured to apply a pulsed direct current voltage as the bias power to the lower electrode at a period defined by the second frequency.

[0025] In an exemplary embodiment, the first period may be a period during which a pulsed DC voltage is not applied to the lower electrode, and the second period may be a period during which a pulsed DC voltage having a negative polarity is applied to the lower electrode.

[0026] In one exemplary embodiment, the plasma processing apparatus may further include a voltage sensor for measuring the potential of the substrate.

[0027] In another exemplary embodiment, an etching method using a plasma processing device is provided. The plasma processing device includes a chamber, a substrate support, a sheath regulator, a high-frequency power supply, and a bias power supply. The substrate support has a lower electrode and an electrostatic chuck. The electrostatic chuck is disposed on the lower electrode. The substrate support is configured to support a substrate placed thereon in the chamber. The sheath regulator is configured to adjust the position of the upper end of the sheath above the edge ring in the vertical direction. The edge ring is configured to surround the edge of the substrate. The high-frequency power supply is configured to generate high-frequency power supplied to generate plasma from gas in the chamber. The high-frequency power has a first frequency. The bias power supply is configured to generate bias power. The bias power supply is electrically connected to the lower electrode. The bias power is set to change the potential of the substrate placed on the electrostatic chuck within a period specified by a second frequency. The second frequency is lower than the first frequency. The etching method is performed in a state where the substrate is placed on the electrostatic chuck. The etching method includes a step of supplying high-frequency power during at least a portion of a first period within the period. During the first period, the potential of the substrate is higher than the average value of the potential of the substrate within the period. The etching method further includes a step of reducing the power level of the high frequency power in the second period within the cycle compared to the power level of the high frequency power in the first period. In the second period, the potential of the substrate is lower than the average value of the potential of the substrate in the cycle. The ions in the plasma generated in the chamber in the first period are accelerated toward the substrate in the second period, and the substrate placed on the electrostatic chuck is etched. In the first period and the second period, the position of the upper end of the sheath in the vertical direction is adjusted by the sheath adjuster.

[0028] In an exemplary embodiment, the supply of high-frequency power may be stopped during the second period.

[0029] In an exemplary embodiment, the sheath adjuster may be configured to apply a voltage to the edge ring in order to adjust the position of the upper end of the sheath in the vertical direction.

[0030] In an exemplary embodiment, the sheath adjuster may be configured to move the edge ring upward in order to adjust the position of the upper end of the sheath in the vertical direction.

[0031] In an exemplary embodiment, the bias power supply may be configured to supply a high-frequency bias power having a second frequency as the bias power to the lower electrode.

[0032] In an exemplary embodiment, the first period may be a period during which the high-frequency bias power output from the bias power supply has a positive potential, and the second period may be a period during which the high-frequency bias power output from the bias power supply has a negative potential.

[0033] In an exemplary embodiment, the bias power supply may be configured to apply a pulsed direct current voltage as the bias power to the lower electrode at a period defined by the second frequency.

[0034] In an exemplary embodiment, the first period may be a period during which a pulsed DC voltage is not applied to the lower electrode, and the second period may be a period during which a pulsed DC voltage having a negative polarity is applied to the lower electrode.

[0035] Hereinafter, various exemplary embodiments will be described in detail with reference to the accompanying drawings. In addition, in each of the drawings, the same or equivalent parts are denoted by the same symbols.

[0036] Figure 1 FIG. 1 is a diagram schematically showing a plasma processing apparatus according to an exemplary embodiment. Figure 1 The plasma processing device 1 shown is a capacitively coupled plasma processing device. The plasma processing device 1 includes a chamber 10. An internal space 10s is provided in the chamber 10. The central axis of the internal space 10s is an axis AX extending in the vertical direction. In one embodiment, the chamber 10 includes a chamber body 12. The chamber body 12 has a substantially cylindrical shape. The internal space 10s is arranged in the chamber body 12. The chamber body 12 is made of aluminum, for example. The chamber body 12 is electrically grounded. A plasma-resistant film is formed on the inner wall surface of the chamber body 12, that is, the wall surface that divides the internal space 10s. The film can be a ceramic film such as a film formed by anodizing or a film formed of yttrium oxide.

[0037] A passage 12p is formed in the side wall of the chamber body 12. The substrate W passes through the passage 12p when being transported between the internal space 10s and the outside of the chamber 10. A gate valve 12g is provided along the side wall of the chamber body 12 to open and close the passage 12p.

[0038] The plasma processing apparatus 1 further includes 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 disk shape. 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 substantially cylindrical shape. The support portion 17 is formed of an insulating material such as quartz.

[0039] The substrate support 16 includes 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 a conductive material such as aluminum and has a substantially disk shape.

[0040] 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 liquid refrigerant or a refrigerant (for example, chlorofluorocarbon) that cools the lower electrode 18 by its gasification is used. A supply device (for example, a cooling unit) for 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 the pipe 23a. The heat exchange medium supplied to the flow path 18f is returned to the supply device via the pipe 23b.

[0041] The electrostatic chuck 20 is provided on the lower electrode 18. When being processed in the internal space 10s, the substrate W is placed on the electrostatic chuck 20 and held by the electrostatic chuck 20.

[0042] 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 aluminum oxide or aluminum nitride. The main body of the electrostatic chuck 20 has a roughly disc shape. The central axis of the electrostatic chuck 20 is roughly consistent with the axis AX. The electrode of the electrostatic chuck 20 is arranged in the main body. The electrode of the electrostatic chuck 20 has a membrane shape. A DC power supply is electrically connected to the electrode of the electrostatic chuck 20 via a switch. When the voltage from the DC power supply is applied to the electrode of the electrostatic chuck 20, an electrostatic attraction is generated between the electrostatic chuck 20 and the substrate W. By the generated electrostatic attraction, the substrate W is attracted to the electrostatic chuck 20 and is held by the electrostatic chuck 20.

[0043] The electrostatic chuck 20 includes a substrate mounting region. The substrate mounting region is a region having a substantially disk shape. The central axis of the substrate mounting region is substantially consistent with the axis AX. When being processed in the chamber 10, the substrate W is mounted on the upper surface of the substrate mounting region.

[0044] In one embodiment, the electrostatic chuck 20 may further include an edge ring mounting area. The edge ring mounting area extends circumferentially in a manner surrounding the substrate mounting area around the central axis of the electrostatic chuck 20. An edge ring FR is mounted on the upper surface of the edge ring mounting area. The edge ring FR has a ring shape. The edge ring FR is mounted on the edge ring mounting area in a manner such that its central axis is consistent with the axis AX. The substrate W is arranged in the area surrounded by the edge ring FR. That is, the edge ring FR is arranged to surround the edge of the substrate W. The edge ring FR may have conductivity. The edge ring FR is formed, for example, of silicon or silicon carbide. The edge ring FR may be formed of a dielectric such as quartz.

[0045] The plasma processing apparatus 1 may further include 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.

[0046] The plasma processing device 1 may further include an insulating region 27. The insulating region 27 is disposed on the support portion 17. The insulating region 27 is disposed radially outside the lower electrode 18 relative to the axis AX. The insulating region 27 extends circumferentially 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 FR is mounted on the insulating region 27 and the edge ring mounting region.

[0047] The plasma processing apparatus 1 further includes an upper electrode 30 . The upper electrode 30 is provided above the substrate support 16 . The upper electrode 30 closes the upper opening of the chamber body 12 together with a member 32 . The member 32 has insulating properties. The upper electrode 30 is supported on the upper portion of the chamber body 12 via the member 32 .

[0048] The upper electrode 30 includes a top plate 34 and a support body 36. The lower surface of the top plate 34 divides the internal space 10s. A plurality of exhaust holes 34a are formed on the top plate 34. The plurality of exhaust holes 34a penetrate the top plate 34 in the plate thickness direction (vertical direction). The top plate 34 is not limited, and is formed of silicon, for example. Alternatively, the top plate 34 may have a structure in which a plasma-resistant film is provided on the surface of an aluminum component. The film may be a ceramic film such as a film formed by anodizing or a film formed of yttrium oxide.

[0049] The support body 36 supports the top plate 34 in a detachable manner. The support body 36 is formed of a conductive material such as aluminum. A gas diffusion chamber 36a is provided inside the support body 36. A 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 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.

[0050] 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 is composed of the gas source group 40, the valve group 41, the flow 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 controller group 42 includes a plurality of flow controllers. The plurality of flow controllers of the flow controller group 42 are respectively mass flow controllers or pressure-controlled flow controllers. The plurality of gas sources of the gas source group 40 are respectively connected to the gas supply pipe 38 via a valve corresponding to the valve group 41, a flow controller corresponding to the flow controller group 42 and a valve corresponding to the valve group 43. The plasma processing device 1 is capable of supplying 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 separately regulated flow rate.

[0051] A baffle 48 is provided between the substrate support 16 or the support portion 17 and the side wall of the chamber body 12. The baffle 48 can be formed by coating a ceramic such as yttrium oxide on an aluminum member, for example. A plurality of through holes are formed in the baffle 48. 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, and can reduce the pressure of the internal space 10s.

[0052] The plasma processing apparatus 1 further includes a high-frequency power supply 61. The high-frequency power supply 61 is a power supply that generates high-frequency power HF. The high-frequency power HF is used to generate plasma from the gas in the chamber 10. The high-frequency power HF has a first frequency. The first frequency is a frequency in the range of 27 to 100 MHz, for example, a frequency of 40 MHz or 60 MHz. In order to supply the high-frequency power HF to the lower electrode 18, the high-frequency power supply 61 is connected to the lower electrode 18 via a matching circuit 63. The matching circuit 63 is configured to match the output impedance of the high-frequency power supply 61 with the impedance of the load side (lower electrode 18 side). In addition, the high-frequency power supply 61 may not be electrically connected to the lower electrode 18, but may be connected to the upper electrode 30 via the matching circuit 63.

[0053] The plasma processing apparatus 1 further includes a bias power supply 62. The bias power supply 62 is electrically connected to the lower electrode 18. The bias power supply 62 generates bias power. The bias power is used to attract ions to the substrate W. The bias power is set to a period P defined by the second frequency. B The potential of the substrate W placed on the electrostatic chuck 20 is changed. The second frequency is lower than the first frequency.

[0054] Figure 2 FIG. 1 is a timing diagram showing high frequency power and bias power used in a plasma processing apparatus according to an exemplary embodiment. Figure 2 As shown, the bias power is a high-frequency bias power LF. In this embodiment, the second frequency, that is, the frequency of the high-frequency bias power LF is a frequency in the range of 50kHz to 27MHz, for example, 400kHz. In this embodiment, in order to supply the high-frequency bias power LF to the lower electrode 18, the bias power supply 62 is connected to the lower electrode 18 via the matching circuit 64. The matching circuit 64 is configured to match the output impedance of the bias power supply 62 with the impedance of the load side (lower electrode 18 side).

[0055] When plasma etching is performed in the plasma processing device 1, gas is supplied to the internal space 10s. Then, by supplying high frequency power HF and bias power, the gas is excited in the internal space 10s. As a result, plasma is generated in the internal space 10s. The substrate W is etched by chemical species such as ions and / or radicals from the generated plasma. That is, plasma etching is performed.

[0056] Below, reference Figure 3 (a) and Figure 3 (b). Figure 3 (a) is a diagram showing an example of the vertical position of the upper end of the sheath in a state where the edge ring is consumed. Figure 3 (b) is a diagram showing an example of the vertical position of the upper end of the sheath to be corrected. Figure 3 (a) and Figure 3 In each of (b), the position of the upper end of the sheath in the vertical direction (hereinafter referred to as "upper end position") is indicated by a dotted line. Figure 3 (a) and Figure 3 In each of (b), the traveling direction of ions relative to the substrate W is indicated by an arrow.

[0057] When plasma etching of the substrate W is performed, as shown in FIG. Figure 3 As shown in (a), the edge ring FR is consumed. When the edge ring FR is consumed, the thickness of the edge ring FR decreases, and the position of the upper surface of the edge ring FR in the vertical direction becomes lower. When the position of the upper surface of the edge ring FR in the vertical direction becomes lower, the upper end position of the sheath above the edge ring FR is lower than the upper end position of the sheath above the substrate W. As a result, the upper end of the sheath is inclined near the edge of the substrate W, and the traveling direction of the ions supplied to the edge of the substrate W becomes inclined relative to the vertical direction.

[0058] In order to correct the traveling direction of the ions to the vertical direction (i.e., the direction perpendicular to the edge of the substrate W), as shown in FIG. Figure 1 As shown, the plasma processing apparatus 1 further includes a sheath adjuster 74. The sheath adjuster 74 is configured to adjust the upper end position of the sheath above the edge ring FR. The sheath adjuster 74 adjusts the upper end position of the sheath above the edge ring FR to eliminate or reduce the difference between the upper end position of the sheath above the edge ring FR and the upper end position of the sheath above the substrate W.

[0059] In one embodiment, the sheath regulator 74 is configured to apply a voltage V to the edge ring FR. N Power supply. Voltage V N In this embodiment, the sheath regulator 74 is connected to the edge ring FR via the filter 75 and the lead wire 76. The filter 75 is a filter for blocking or reducing high-frequency power flowing into the sheath regulator 74.

[0060] Voltage V N It can be a DC voltage or a high frequency voltage. Voltage V N The level of V determines the adjustment amount of the upper end position of the sheath. The adjustment amount of the upper end position of the sheath, that is, the voltage V N The level of V is determined based on a parameter reflecting the thickness of the edge ring FR. The parameter may be a measured value of the thickness of the edge ring FR measured optically or electrically, a position of the upper surface of the edge ring FR measured optically or electrically in the vertical direction, or a time period for which the edge ring FR is exposed to the plasma. Using such a parameter and the voltage V N The prescribed relationship between the levels determines the voltage V N For example, the predetermined parameters and voltage V N The relationship between the levels is specified so that if the thickness of the edge ring FR decreases, the voltage V N When the voltage V with the determined level increases N When applied to the edge ring FR, as Figure 3 As shown in (b), the difference between the upper end position of the sheath above the edge ring FR and the upper end position of the sheath above the substrate W is eliminated or reduced.

[0061] In addition, the voltage V N It can be a pulsed high frequency voltage or a pulsed DC voltage. N It can be periodically applied to the edge ring FR. When the pulsed DC voltage is used as the voltage V N When a voltage V is periodically applied to the edge ring FR N During the period when the voltage V is applied to the edge ring FR N The level can be changed.

[0062] When the upper end position of the sheath is corrected by the sheath adjuster 74, the impedance of the path of the high frequency power reaching the plasma via the edge ring becomes larger. This is because when the voltage V is applied to the edge ring FR, the high frequency power of the plasma is increased. N When the upper end position of the sheath is adjusted by adjusting the upper end position of the sheath, the thickness of the sheath increases above the edge ring FR. When the impedance of the path of the high-frequency power reaching the plasma via the edge ring increases, the power level of the high-frequency power supplied to the edge ring decreases. Furthermore, when the impedance of the path of the high-frequency power reaching the plasma via the edge ring increases, the power level of the high-frequency power supplied to the substrate W increases. As a result, relative to the etching rate at the edge of the substrate W, the etching rate of the substrate W further inside than the edge becomes higher.

[0063] In the plasma processing apparatus 1 , in order to reduce the difference between the etching rate at the edge of the substrate and the etching rate of the substrate inside the edge, the control unit MC controls the supply timing of the high-frequency power HF.

[0064] The control unit MC is a computer including a processor, a storage device, an input device, a display device, etc., and controls each unit of the plasma processing apparatus 1. The control unit MC executes a control program stored in the storage device, and controls each unit of the plasma processing apparatus 1 according to the process data stored in the storage device. Through the control by the control unit MC, the process specified by the process data is executed in the plasma processing apparatus 1. The etching method according to the embodiment described below can be executed in the plasma processing apparatus 1 through the control of each unit of the plasma processing apparatus 1 by the control unit MC.

[0065] As described above, the control unit MC can determine the voltage V N The above parameters are related to the voltage V N The prescribed relationship between the levels of V and V can be stored in the storage device of the control unit MC as data in the form of a function or table. The control unit MC can control the sheath regulator 74 to set the voltage V having the determined level to N Applied to the edge ring FR.

[0066] The control unit MC controls the high frequency power supply 61 so that B The high frequency power HF may be supplied during at least a portion of the first period P1 in the period P1. The high frequency power HF may be supplied during the entire first period P1. During the first period P1, the potential of the substrate W placed on the electrostatic chuck 20 is higher than that of the period P1. B The average potential V of the substrate W within AVE The control unit MC controls the high frequency power supply 61 so that B In the second period P2, the power level of the high frequency power HF is reduced compared to the power level of the high frequency power HF in the first period P1. In the second period P2, the potential of the substrate W placed on the electrostatic chuck 20 is lower than the average value V AVE In one embodiment, the control unit MC may control the high frequency power source 61 to stop supplying the high frequency power HF during the second period P2. The control unit MC controls the sheath adjuster 74 during the first period P1 and the second period P2 to adjust the vertical position of the upper end of the sheath.

[0067] In the plasma processing apparatus 1, during the period P of the bias power BThe high-frequency power HF is supplied during at least a portion of the first period P1 within the plasma. During the first period P1, the potential difference between the substrate W and the plasma is small, and the etching of the substrate W proceeds relatively slowly, or the etching of the substrate W is not substantially performed. On the other hand, during the second period P2, the potential difference between the substrate W and the plasma is large, and the etching of the substrate W proceeds, but the power level of the high-frequency power HF is set to a low level or zero. Therefore, according to the plasma processing apparatus 1, even if the position of the upper end of the sheath in the vertical direction is adjusted by the sheath adjuster 74, the difference between the etching rate at the edge of the substrate W and the etching rate of the substrate further inside than the edge becomes smaller.

[0068] In one embodiment, if Figure 2 As shown, the high-frequency bias power LF is used as the bias power. The first period P1 may be a period during which the high-frequency bias power LF output from the bias power supply 62 has a positive potential. The second period P2 may be a period during which the high-frequency bias power LF output from the bias power supply 62 has a negative potential. In this embodiment, the synchronization pulse, the delay time, and the supply time are given to the high-frequency power supply 61 from the control unit MC. The synchronization pulse is synchronized with the high-frequency bias power LF. The delay time is determined from the period P determined by the synchronization pulse. B The supply time is the length of the supply time of the high frequency power HF. The high frequency power source 61 is B The start time of the supply time is delayed by the delay time to supply the high-frequency power HF to the lower electrode 18. As a result, in the first period P1, the high-frequency power HF is supplied to the lower electrode 18. In addition, the delay time may be zero.

[0069] In one embodiment, the plasma processing apparatus 1 may further include a voltage sensor 78. The voltage sensor 78 is configured to directly or indirectly measure the potential of the substrate W. Figure 1 In the example shown, the voltage sensor 78 is configured to measure the potential of the lower electrode 18. Specifically, the voltage sensor 78 measures the potential of the power supply circuit connected between the lower electrode 18 and the bias power supply 62. In this embodiment, the control unit MC increases the potential of the substrate W measured by the voltage sensor 78 to a value higher than that during the period P. B The average potential V of the substrate W in AVE The period is determined as the first period P1. The control unit MC controls the high-frequency power source 61 to supply the high-frequency power HF during the first period P1. The control unit MC sets the potential of the substrate W measured by the voltage sensor 78 to be lower than the average value V AVEThe period of time during which the substrate W is subjected to the first period P1 is determined as the second period P2. The control unit MC controls the high-frequency power source 61 so that the power level of the high-frequency power HF in the second period P2 is reduced compared to the power level of the high-frequency power HF in the first period P1, or stops supplying the high-frequency power HF. AVE It can be a preset value.

[0070] Another embodiment will be described below. Figure 4 1 is a timing diagram showing high-frequency power and bias power used in a plasma processing apparatus according to another exemplary embodiment. In a plasma processing apparatus 1 according to another embodiment, a bias power supply 62 is configured to apply a pulsed DC voltage VB as bias power to a lower electrode 18. The DC voltage VB is applied to the lower electrode 18 at a repetition frequency as a second frequency. In an embodiment using a pulsed DC voltage VB, the second frequency is greater than 50 kHz and less than 27 MHz. In this embodiment, the matching circuit 64 can be omitted. In this embodiment, the first period P1 can be a period during which the DC voltage VB is not applied to the lower electrode. The second period P2 can be a period during which a pulsed DC voltage VB having a negative polarity is applied to the lower electrode. Alternatively, as described above, the first period P1 and the second period P2 can be determined based on the potential of the substrate W measured by the voltage sensor 78. In other respects, the plasma processing apparatus 1 using the DC voltage VB as bias power can be the same as the plasma processing apparatus 1 using the high-frequency bias power LF as bias power.

[0071] Below, reference Figure 5 , Figure 6 (a) and Figure 6 (b) A plasma processing apparatus according to still another embodiment will be described. Figure 5 This is a diagram schematically showing a plasma processing apparatus according to still another embodiment. Figure 6 (a) is a diagram showing an example of the vertical position of the upper end of the sheath in a state where the edge ring is consumed, Figure 6 (b) is a diagram showing an example of the vertical position of the upper end of the sheath to be corrected. Figure 6 (a) and Figure 6 In each of (b), the upper end position of the sheath is indicated by a dotted line. Figure 6 (a) and Figure 6 In each of (b), the traveling direction of ions relative to the substrate W is indicated by an arrow.

[0072] Figure 5The plasma processing apparatus 1B shown is different from the plasma processing apparatus 1 in that an edge ring FRB is used instead of the edge ring FR. Also, the plasma processing apparatus 1B is different from the plasma processing apparatus 1 in that a sheath regulator 74B is provided instead of the sheath regulator 74. In other respects, the structure of the plasma processing apparatus 1B may be the same as that of the plasma processing apparatus 1.

[0073] like Figure 6 (a) and Figure 6 As shown in (b), the edge ring FRB has a first annular portion FR1 and a second annular portion FR2. The first annular portion FR1 and the second annular portion FR2 are separated from each other. The first annular portion FR1 is annular and plate-shaped, and is placed on the edge ring holding area in a manner extending around the axis AX. The substrate W is placed on the substrate holding area in a manner such that its edge is located on the first annular portion FR1. The second annular portion FR2 is annular and plate-shaped, and is placed on the edge ring holding area in a manner extending around the axis AX. The second annular portion FR2 is located radially outside the first annular portion FR1.

[0074] The sheath adjuster 74B is a moving device configured to move the edge ring FRB upward in order to adjust the position of the upper surface of the edge ring FRB in the vertical direction. Specifically, the sheath adjuster 74B is configured to move the second annular portion FR2 upward in order to adjust the position of the upper surface of the second annular portion FR2 in the vertical direction. In one example, the sheath adjuster 74B includes a drive device 74a and a shaft 74b. The shaft 74b supports the second annular portion FR2 and extends downward from the second annular portion FR2. The drive device 74a is configured to generate a driving force for moving the second annular portion FR2 in the vertical direction via the shaft 74b.

[0075] When plasma etching of the substrate W is performed, as shown in FIG. Figure 6 As shown in (a), the edge ring FRB is consumed. When the edge ring FRB is consumed, the thickness of the second annular portion FR2 decreases, and the position of the upper surface of the second annular portion FR2 in the vertical direction becomes lower. When the position of the upper surface of the second annular portion FR2 in the vertical direction becomes lower, the upper end position of the sheath on the edge ring FRB is lower than the upper end position of the sheath above the substrate W. As a result, the upper end of the sheath is inclined near the edge of the substrate W, and the traveling direction of the ions supplied to the edge of the substrate W becomes inclined relative to the vertical direction.

[0076] In order to correct the traveling direction of ions to the vertical direction, the sheath adjuster 74B is configured to adjust the upper end position of the sheath on the edge ring FRB. The sheath adjuster 74B adjusts the upper end position of the sheath on the edge ring FRB to eliminate or reduce the difference between the upper end position of the sheath on the edge ring FRB and the upper end position of the sheath above the substrate W. Specifically, the sheath adjuster 74B moves the second annular portion FR2 upward so that the position of the upper surface of the second annular portion FR2 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.

[0077] The adjustment amount of the upper end position of the sheath, that is, the movement amount of the second annular portion FR2 is determined based on a parameter reflecting the thickness of the edge ring FRB, that is, the thickness of the second annular portion FR2. The parameter can be a measured value of the thickness of the second annular portion FR2 measured optically or electrically, the position of the upper surface of the second annular portion FR2 in the vertical direction measured optically or electrically, or the length of time the edge ring FRB is exposed to the plasma. The movement amount of the second annular portion FR2 is determined using a prescribed relationship between such a parameter and the movement amount of the second annular portion FR2. For example, a prescribed relationship between a parameter and the movement amount of the second annular portion FR2 is predetermined so that if the thickness of the second annular portion FR2 decreases, the movement amount of the second annular portion FR2 increases. As Figure 6 As shown in (b), when the second annular portion FR2 moves upward by a predetermined amount, the difference between the upper end position of the sheath on the edge ring FRB and the upper end position of the sheath above the substrate W is eliminated or reduced.

[0078] In the plasma processing apparatus 1B, as described above, the control unit MC can determine the movement amount of the second annular portion FR2. The predetermined relationship between the above parameters and the movement amount of the second annular portion FR2 can be stored in a storage device of the control unit MC as data in a function or table format. The control unit MC can control the sheath adjuster 74B so that the second annular portion FR2 moves upward only by the determined movement amount.

[0079] When the upper end position of the sheath is corrected by the sheath adjuster 74B, the impedance of the path of the high-frequency power reaching the plasma via the edge ring FRB becomes larger. This is because the gap directly below the second annular portion FR2 becomes wider. When the impedance of the path of the high-frequency power reaching the plasma via the edge ring FRB becomes larger, the power level of the high-frequency power supplied to the edge ring FRB decreases. Also, when the impedance of the path of the high-frequency power reaching the plasma via the edge ring FRB becomes larger, the power level of the high-frequency power supplied to the substrate W increases relatively. As a result, relative to the etching rate of the edge of the substrate W, the etching rate of the substrate W that is closer to the inside than the edge becomes higher. Therefore, in the plasma processing apparatus 1B, as in the plasma processing apparatus 1, the supply timing of the high-frequency power HF is controlled by the control unit MC.

[0080] Figure 7 This is a diagram showing another example of an edge ring. Figure 7 In the edge ring FRB shown, the first annular portion FR1 has an inner circumference and an outer circumference. The upper surface of the inner circumference is located lower in the vertical direction than the upper surface of the outer circumference in the vertical direction. The substrate W is placed on the substrate placement area in such a way that its edge is located on or above the inner circumference of the first annular portion FR1. The second annular portion FR2 is arranged on the inner circumference of the first annular portion FR1 in such a way as to surround the edge of the substrate W. That is, in Figure 7 In the edge ring FRB shown, the second annular portion FR2 is arranged inside the outer periphery of the first annular portion FR1. Figure 7 In the case of the edge ring FRB shown, the shaft 74b of the sheath adjuster 74B extends downward from the second annular portion FR2 through the inner peripheral portion of the first annular portion FR1.

[0081] Below, reference Figure 8 . Figure 8 is a flow chart showing an etching method according to an exemplary embodiment. Figure 8 The etching method MT shown is performed using any of the plasma processing apparatuses according to the various embodiments, such as the plasma processing apparatus 1 and the plasma processing apparatus 1B described above.

[0082] The etching method MT is performed in a state where the substrate W is placed on the electrostatic chuck 20. In the etching method MT, gas is supplied from the gas supply unit into the chamber 10. Then, the pressure in the chamber 10 is set to a predetermined pressure by the exhaust device 50. Then, in the etching method MT, as the bias power, the high-frequency bias power LF or the pulsed DC voltage VB is supplied to the lower electrode 18.

[0083] In the etching method MT, step ST1 is performed. In the period P of the bias power B Step ST1 is performed during at least a portion of the first period P1 within the bias power. In step ST1, high frequency power HF is supplied. In the following step ST2, during the period P of the bias power B In step ST2, the power level of the high frequency power HF is reduced compared to the power level of the high frequency power HF in the first period P1, or the supply of the high frequency power HF is stopped. In the etching method MT, the ions in the plasma generated in the chamber 10 in the first period P1 are accelerated toward the substrate W in the second period P2, and the substrate W is etched. In the etching method MT, in the first period P1 and the second period P2, the position of the upper end of the sheath in the vertical direction is adjusted by the sheath adjuster (sheath adjuster 74 or sheath adjuster 74B).

[0084] In step ST3, it is determined whether the stop condition is satisfied. When the number of repetitions of step ST1 and step ST2 reaches a predetermined number of times, the stop condition is satisfied. If it is determined in step ST3 that the stop condition is not satisfied, step ST1 and step ST2 are performed again. On the other hand, if it is determined in step ST3 that the stop condition is satisfied, the execution of etching method MT ends.

[0085] Various exemplary embodiments have been described above, but the present invention is not limited to the exemplary embodiments described above, and various additions, omissions, substitutions, and changes may be made. Furthermore, elements in different embodiments may be combined to form other embodiments.

[0086] The plasma processing apparatus according to another embodiment may be a capacitively coupled plasma processing apparatus different from the plasma processing apparatus 1 and the plasma processing apparatus 1B. Furthermore, the plasma processing apparatus according to another embodiment may be an inductively coupled plasma processing apparatus. Furthermore, the plasma processing apparatus according to another embodiment may be an ECR (electron cyclotron resonance) plasma processing apparatus. Furthermore, the plasma processing apparatus according to another embodiment may be a plasma processing apparatus that generates plasma using surface waves such as microwaves.

[0087] It can be understood from the above description that the various embodiments of the present invention are described in this specification for the purpose of explanation, and various changes can be made without departing from the scope and purpose of the present invention. Therefore, the various embodiments disclosed in this specification are not intended to be limited, and the true scope and purpose can be shown by the scope of the attached technical solutions.

Claims

1. A plasma processing device, comprising: Chamber; a substrate support disposed in the chamber and comprising an electrode; an edge ring disposed to surround a substrate on the substrate support; a bias RF generator electrically connected to the electrode and configured to generate a bias RF signal having a first frequency; a source RF generator configured to generate a source RF signal to generate a plasma from a gas in the chamber, the source RF signal having a second frequency greater than the first frequency, the source RF signal having a first power level during a first half of a cycle defined by the first frequency and having a second power level during a second half of the cycle, the second power level being less than the first power level; as well as A power supply is configured to apply a voltage signal to the edge ring based on consumption of the edge ring.

2. The plasma processing apparatus according to claim 1, wherein: The bias RF signal has a positive potential during the first half period and has a negative potential during the second half period.

3. The plasma processing apparatus according to claim 2, wherein: The second power level is a zero power level.

4. The plasma processing apparatus according to claim 2, wherein: The first frequency is in the range of 50 kHz to 27 MHz, and the second frequency is in the range of 27 MHz to 100 MHz.

5. The plasma processing apparatus according to claim 1, wherein: The source RF generator is connected to the electrode of the substrate supporter through a matching circuit. 6 . The plasma processing apparatus according to claim 1 , further comprising a voltage sensor configured to directly or indirectly measure a potential of the substrate.

7. A plasma processing device, comprising: Chamber; a substrate support disposed in the chamber and comprising an electrode; an edge ring disposed to surround a substrate on the substrate support; a first power supply configured to apply a first voltage signal to the electrode, the first voltage signal having a first voltage level during a first period in a repetitive time period and having a second voltage level during a second period in the repetitive time period, the absolute value of the second voltage level being greater than the absolute value of the first voltage level; an RF generator configured to generate an RF signal to generate a plasma from a gas in the chamber, the RF signal having a first power level during the first period and a second power level during the second period, the second power level being less than the first power level; as well as A second power supply is configured to apply a second voltage signal to the edge ring based on consumption of the edge ring.

8. The plasma processing apparatus according to claim 7, wherein: The first voltage level has a negative polarity.

9. The plasma processing apparatus according to claim 8, wherein: The second voltage level is a zero voltage level.

10. The plasma processing apparatus according to claim 7, wherein: The second power level is a zero power level.

11. The plasma processing apparatus according to claim 7, wherein: The RF signal has a frequency in the range of 27 MHz to 100 MHz, and the first voltage signal has a repetition frequency in the range of 50 kHz to 27 MHz.

12. The plasma processing apparatus according to claim 7, wherein: The source RF generator is connected to the electrode of the substrate supporter through a matching circuit. 13 . The plasma processing apparatus of claim 7 , further comprising a voltage sensor configured to directly or indirectly measure a potential of the substrate.

14. A plasma processing device, comprising: Chamber; a substrate support disposed in the chamber and comprising an electrode; an edge ring disposed to surround a substrate on the substrate support; a bias RF generator electrically connected to the electrode and configured to generate a bias RF signal having a first frequency; a source RF generator configured to generate a source RF signal to generate a plasma from a gas in the chamber, the source RF signal having a second frequency greater than the first frequency, the source RF signal having a first power level during a first half of a cycle defined by the first frequency and having a second power level during a second half of the cycle, the second power level being less than the first power level; as well as A drive device is configured to move the edge ring upward based on consumption of the edge ring.

15. The plasma processing apparatus according to claim 14, wherein: The second power level is a zero power level.

16. The plasma processing apparatus according to claim 14, wherein: The first frequency is in the range of 50 kHz to 27 MHz, and the second frequency is in the range of 27 MHz to 100 MHz.

17. The plasma processing apparatus according to claim 14, wherein: The source RF generator is connected to the electrode of the substrate supporter through a matching circuit. 18 . The plasma processing apparatus of claim 14 , further comprising a voltage sensor configured to directly or indirectly measure a potential of the substrate.

19. A plasma processing device comprising: Chamber; a substrate support disposed in the chamber and comprising an electrode; an edge ring disposed to surround a substrate on the substrate support; a power supply configured to apply a voltage signal to the electrode, the voltage signal having a first voltage level during a first period in a repetitive time period and having a second voltage level during a second period in the repetitive time period, the absolute value of the second voltage level being greater than the absolute value of the first voltage level; an RF generator configured to generate an RF signal to generate a plasma from a gas in the chamber, the RF signal having a first power level during the first period and a second power level during the second period, the second power level being less than the first power level; as well as A drive device is configured to move the edge ring upward based on consumption of the edge ring.

20. The plasma processing apparatus according to claim 19, wherein: The first voltage level has a negative polarity.

21. The plasma processing apparatus according to claim 20, wherein: The second voltage level is a zero voltage level.

22. The plasma processing apparatus according to claim 19, wherein: The second power level is a zero power level.

23. The plasma processing apparatus according to claim 19, wherein: The RF signal has a frequency in the range of 27 MHz to 100 MHz, and the voltage signal has a repetition frequency in the range of 50 kHz to 27 MHz.

24. The plasma processing apparatus according to claim 19, wherein: The source RF generator is connected to the electrode of the substrate supporter through a matching circuit. 25 . The plasma processing apparatus of claim 19 , further comprising a voltage sensor configured to directly or indirectly measure a potential of the substrate.

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