Plasma processing apparatus and plasma processing method

Abstract

To provide a technique capable of adjusting the thickness of the sheath on an edge ring and adjusting the distribution of plasma density in the radial direction.SOLUTION: A plasma processing apparatus disclosed herein includes a chamber, a substrate support, a high frequency power supply, and a bias power supply. The high frequency power supply supplies high frequency power to a high frequency electrode. The bias power supply provides an electrical bias to the bias electrode. An edge ring mounted on the substrate support is subject to some or another electrical bias. The outer ring extends radially outward with respect to the edge ring and receives some of the high frequency power. The power level of the high frequency power is changed in synchronization with the electrical bias within each cycle of the electrical bias.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] SUMMARY OF THE DISCLOSURE Exemplary embodiments of the present disclosure relate to a plasma processing apparatus and a plasma processing method. [Background technology]

[0002] A plasma processing apparatus is used for plasma processing of a substrate. The plasma processing apparatus includes a chamber, an electrostatic chuck, and a lower electrode. The electrostatic chuck and the lower electrode are provided in the chamber. The electrostatic chuck is provided on the lower electrode. The electrostatic chuck supports an edge ring placed thereon. The edge ring is sometimes called a focus ring. The electrostatic chuck supports a substrate placed in a region surrounded by the edge ring. When plasma processing is performed in the plasma processing apparatus, a gas is supplied into the chamber. Also, high frequency power is supplied to the lower electrode. A plasma is formed from the gas in the chamber. The substrate is processed by chemical species such as ions and radicals from the plasma.

[0003] When plasma processing is performed, the edge ring is consumed and the thickness of the edge ring is reduced. When the thickness of the edge ring is reduced, the position of the upper end of the plasma sheath (hereinafter referred to as the "sheath") above the edge ring is lowered. The vertical position of the upper end of the sheath above the edge ring and the vertical position of the upper end of the sheath above the substrate should be equal. Japanese Patent Laid-Open Publication No. 2008-227063 (hereinafter referred to as "Patent Document 1") discloses a plasma processing apparatus that makes it possible to adjust the vertical position of the upper end of the sheath above the edge ring. The plasma processing apparatus described in Patent Document 1 is configured to apply a DC voltage to the edge ring. In addition, the plasma processing apparatus described in Patent Document 1 is configured to adjust the power level of the high frequency power supplied to the lower electrode when the DC voltage is applied to the edge ring. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-227063 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure provides techniques that allow for adjustment of the sheath thickness on the edge ring and adjustment of the radial plasma density distribution. [Means for solving the problem]

[0006] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a radio frequency power supply, and a bias power supply. The substrate support has a bias electrode. The radio frequency power supply is configured to generate radio frequency power that is supplied to the radio frequency electrode to generate a plasma above a substrate supported by the substrate support in the chamber. The bias power supply is connected to the bias electrode through an electrical path. An edge ring is mounted on the substrate support. The edge ring is electrically connected to the bias power supply through an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to a separate bias power supply. An outer ring extends radially outwardly relative to the edge ring. The outer ring is electrically connected to the radio frequency power supply to receive a portion of the radio frequency power. The radio frequency power supply is configured to change a power level of the radio frequency power in synchronization with the electrical bias within each period of the electrical bias output from the bias power supply to the bias electrode. Effect of the Invention

[0007] According to one exemplary embodiment, it is possible to adjust the thickness of the sheath on the edge ring and adjust the distribution of plasma density in the radial direction. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment; [Diagram 2] 2(a) and 2(b) are each a timing chart of an example of high frequency power and electrical bias used in the plasma processing apparatus shown in FIG. [Diagram 3] 3(a) and 3(b) are timing charts of another example of high frequency power and electrical bias used in the plasma processing apparatus shown in FIG. [Figure 4] FIG. 13 is a schematic diagram of a plasma processing apparatus according to another exemplary embodiment. [Diagram 5] 5(a) and 5(b) are timing charts of an example of the first high frequency power, the second high frequency power, and the electric bias used in the plasma processing apparatus shown in FIG. [Figure 6] 6(a) and 6(b) are timing charts of the first high frequency power, the second high frequency power, and the electric bias in another example used in the plasma processing apparatus shown in FIG. [Figure 7] FIG. 13 is a schematic diagram of a plasma processing apparatus according to yet another exemplary embodiment. [Figure 8] FIG. 13 is a schematic diagram of a plasma processing apparatus according to yet another exemplary embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Various exemplary embodiments are described below.

[0010] In one exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a radio frequency power supply, and a bias power supply. The substrate support has a bias electrode. The radio frequency power supply is configured to generate radio frequency power that is supplied to the radio frequency electrode to generate a plasma above a substrate supported by the substrate support in the chamber. The bias power supply is connected to the bias electrode through an electrical path. An edge ring is mounted on the substrate support. The edge ring is electrically connected to the bias power supply through an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to a separate bias power supply. An outer ring extends radially outwardly relative to the edge ring. The outer ring is electrically connected to the radio frequency power supply to receive a portion of the radio frequency power. The radio frequency power supply is configured to change a power level of the radio frequency power in synchronization with the electrical bias within each period of the electrical bias output from the bias power supply to the bias electrode.

[0011] According to the above embodiment, the level of the negative bias on the edge ring is adjusted by an impedance adjuster or another bias power supply. Therefore, according to the above embodiment, it is possible to adjust the thickness of the sheath on the edge ring. Also, in the above embodiment, the power level of the high frequency power supplied to the outer ring is changed in each period of the electric bias. Therefore, according to the above embodiment, it is possible to adjust the distribution of plasma density in the radial direction in each period of the electric bias.

[0012] In one exemplary embodiment, the plasma processing apparatus may further include a first electrode and a second electrode. The first electrode is electrically coupled to the edge ring. The first electrode may be capacitively coupled to the edge ring. The second electrode is electrically coupled to the outer ring. The second electrode may be capacitively coupled to the outer ring. An impedance adjuster provides a variable impedance between the bias electrode and the first electrode or between the electrical path and the first electrode. The outer ring receives a portion of the RF power or another RF power from another RF power source via the second electrode.

[0013] In one exemplary embodiment, the RF power source may be configured to provide pulses of RF power to the RF electrode and the outer ring at the same time period within each period of the electrical bias.

[0014] In one exemplary embodiment, the same period may be a first period during which the electrical bias has a voltage equal to or greater than the average voltage of the electrical bias within the period or a second period during which the electrical bias has a voltage less than the average voltage within the period. If a pulse of RF power is supplied to the RF electrode and the outer ring during the first period, the density of the plasma above the substrate and around the outer ring can be increased. Also, if a pulse of RF power is supplied to the RF electrode and the outer ring during the second period, the density of the plasma above the substrate and around the outer ring can be increased relative to the density of the plasma above the substrate.

[0015] In one exemplary embodiment, the substrate support may include a base and an electrostatic chuck disposed on the base.

[0016] In one exemplary embodiment, the base may provide a lower electrode that is a bias electrode. The lower electrode may be a radio frequency electrode. A radio frequency power source may be electrically connected to the lower electrode via the electrical path.

[0017] In one exemplary embodiment, the plasma processing apparatus may further include an impedance adjuster, which provides a variable impedance between the electrical path and the outer ring or between the lower electrode and the outer ring.

[0018] In one exemplary embodiment, the plasma processing apparatus may further include a filter connected between the impedance adjuster and the second electrode, the filter providing a variable impedance between the electrical path and the outer ring or between the lower electrode and the outer ring. The filter may have a frequency characteristic that selectively passes high frequency power with respect to the electrical bias supplied from the bias power supply to the lower electrode.

[0019] In one exemplary embodiment, the bias electrode may be disposed within the electrostatic chuck. The base may provide a lower electrode that is a radio frequency electrode. The radio frequency power source may be electrically connected to the lower electrode. In one exemplary embodiment, the plasma processing apparatus may further include an impedance adjuster that provides a variable impedance between an electrical path connecting the radio frequency power source to the lower electrode and the outer ring, and between the lower electrode and the outer ring.

[0020] In another exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support, a first high frequency power supply, a bias power supply, and a second high frequency power supply. The substrate support has a bias electrode. The first high frequency power supply is configured to generate a first high frequency power supplied to the high frequency electrode to generate a plasma above a substrate supported by the substrate support in the chamber. The bias power supply is connected to the bias electrode through an electrical path. The second high frequency power supply is configured to generate a second high frequency power supplied to the outer ring. The outer ring extends radially outwardly relative to an edge ring mounted on the substrate support. The edge ring is electrically connected to the bias power supply through an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to another bias power supply. The second high frequency power supply is configured to change a power level of the second high frequency power in synchronization with the electrical bias within each period of the electrical bias output from the bias power supply to the bias electrode.

[0021] According to the above embodiment, the level of the negative bias on the edge ring is adjusted by an impedance adjuster or another bias power supply. Therefore, according to the above embodiment, it is possible to adjust the thickness of the sheath on the edge ring. Also, in the above embodiment, the power level of the second high frequency power supplied to the outer ring is changed in each period of the electric bias. Therefore, according to the above embodiment, it is possible to adjust the distribution of plasma density in the radial direction in each period of the electric bias.

[0022] In one exemplary embodiment, the plasma processing apparatus may further include a first electrode and a second electrode. The first electrode is electrically coupled to the edge ring. The first electrode may be capacitively coupled to the edge ring. The second electrode is electrically coupled to the outer ring. The second electrode may be capacitively coupled to the outer ring. An impedance adjuster provides a variable impedance between the bias electrode and the first electrode or between the electrical path and the first electrode. The outer ring receives a second RF power via the second electrode.

[0023] In one exemplary embodiment, the substrate support may include a base and an electrostatic chuck disposed on the base.

[0024] In one exemplary embodiment, the base may provide a lower electrode that is a bias electrode. The lower electrode may be a radio frequency electrode. A radio frequency power source may be electrically connected to the lower electrode via the electrical path.

[0025] In one exemplary embodiment, the bias electrode may be disposed within the electrostatic chuck. The base may provide a lower electrode that is a radio frequency electrode. The first radio frequency power source may be electrically connected to the lower electrode.

[0026] In one exemplary embodiment, the second RF power source may be configured to provide a pulse of the second RF power to the outer ring at the same time period within each period of the electrical bias.

[0027] In one exemplary embodiment, each period of the electric bias includes a first period during which the electric bias has a voltage equal to or greater than the average voltage of the electric bias in the period or a second period during which the electric bias has a voltage lower than the average voltage in the period. The same period may be the first period. In this embodiment, the radial plasma density distribution is adjusted by the ratio of the second high frequency power supplied to the outer ring and the first high frequency power supplied to the high frequency electrode during the period when the sheath on the substrate is thin.

[0028] In one exemplary embodiment, the first high frequency power source may supply a continuous wave of the first high frequency power during both the first time period and the second time period, or may supply a pulse of the first high frequency power during the second time period.

[0029] In one exemplary embodiment, the first radio frequency power source may provide a pulse of a first radio frequency power for a first duration.

[0030] In one exemplary embodiment, the outer ring may extend around the edge ring.

[0031] In one exemplary embodiment, the bias power supply may be configured to provide a high frequency bias power to the bias electrode or to periodically apply a pulsed voltage or a voltage having an arbitrary waveform to the lower electrode. The pulsed voltage may have a negative polarity. The pulsed voltage may be a pulsed negative polarity DC voltage.

[0032] In yet another exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a step (a1) of supplying high frequency power from a high frequency power source to a high frequency electrode to generate plasma above a substrate supported by a substrate support in a chamber of a plasma processing apparatus. The plasma processing method further includes a step (b1) of applying an electric bias from a bias power source to a bias electrode of the substrate support. The plasma processing apparatus includes a chamber, a substrate support, a high frequency power source, and a bias power source connected to the bias electrode via an electrical path. An edge ring is mounted on the substrate support. The edge ring is electrically connected to the bias power source via an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to another bias power source. An outer ring extends radially outward relative to the edge ring. The outer ring is electrically connected to the high frequency power source to receive a portion of the high frequency power. In the step (a1), the high frequency power source changes a power level of the high frequency power in synchronization with the electrical bias within each period of the electrical bias output from the bias power source to the bias electrode.

[0033] In one exemplary embodiment, in step (a1), the radio frequency power source may supply pulses of radio frequency power to the radio frequency electrode and the outer ring during a same period in each period of the electrical bias, which may be a first period during which the electrical bias has a voltage equal to or greater than an average voltage of the electrical bias during the period or a second period during which the electrical bias has a voltage less than the average voltage during the period.

[0034] In yet another exemplary embodiment, a plasma processing method is provided. The plasma processing method includes a step (a2) of supplying a first high frequency power from a first high frequency power source to a high frequency electrode to generate a plasma above a substrate supported by a substrate support in a chamber of the plasma processing apparatus. The plasma processing method further includes a step (b2) of providing an electrical bias from a bias power source to a bias electrode of the substrate support. The plasma processing method further includes a step (c2) of supplying a second high frequency power from a second high frequency power source to an outer ring. The plasma processing apparatus includes a chamber, a substrate support, a first high frequency power source, a bias power source connected to the bias electrode via an electrical path, and a second high frequency power source. An edge ring is mounted on the substrate support. The edge ring is electrically connected to the bias power source via an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to another bias power source. The outer ring extends radially outward relative to the edge ring. In step (c2), the second high frequency power supply changes the power level of the second high frequency power in synchronization with the electric bias within each period of the electric bias.

[0035] In one exemplary embodiment, in step (c2), the second high frequency power supply may supply pulses of the second high frequency power to the outer ring during the same period in each period of the electric bias. Each period of the electric bias may include a first period during which the electric bias has a voltage equal to or greater than the average voltage of the electric bias during the period, or a second period during which the electric bias has a voltage lower than the average voltage during the period. The same period may be the first period.

[0036] Various exemplary embodiments will now be described in detail with reference to the drawings, in which the same or corresponding parts are designated by the same reference numerals.

[0037] Fig. 1 is a schematic diagram of a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus 1 shown in Fig. 1 is a capacitively coupled plasma processing apparatus. The plasma processing apparatus 1 includes a chamber 10. The chamber 10 provides an internal space 10s therein. The central axis of the internal space 10s is an axis AX extending in the vertical direction.

[0038] In one embodiment, the chamber 10 may include a chamber body 12. The chamber body 12 has a generally cylindrical shape. An 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 plasma-resistant film is formed on the inner wall surface of the chamber body 12, i.e., the wall surface defining the internal space 10s. This film may be a ceramic film, such as a film formed by anodization or a film formed from yttrium oxide.

[0039] The sidewall of the chamber body 12 provides a passage 12p. The substrate W passes through the passage 12p when being transferred between the internal space 10s and the outside of the chamber 10. A gate valve 12g is provided along the sidewall of the chamber body 12 to open and close the passage 12p.

[0040] The plasma processing apparatus 1 further includes a substrate support 16. The substrate support 16 is configured to support the substrate W placed thereon in the chamber 10. The substrate W has a substantially disk shape. The substrate W is placed on the substrate support 16 such that its center is located on the axis line AX. The substrate support 16 is configured to further support an edge ring ER. The edge ring ER has an annular shape. The edge ring ER may be conductive. The edge ring ER is made of, for example, silicon or silicon carbide. The edge ring ER is placed on the substrate support 16 such that its central axis coincides with the axis line AX. The substrate W is disposed on the substrate support 16 and within a region surrounded by the edge ring ER.

[0041] The substrate support 16 may be surrounded by an insulating portion 17. The insulating portion 17 extends circumferentially outside the substrate support 16 in a radial direction relative to the axis line AX. The insulating portion 17 is formed of an insulating material such as quartz. The insulating portion 17 may support the substrate support 16.

[0042] The substrate support 16 has a base 18. The substrate support 16 may further have an electrostatic chuck 20. The base 18 and the electrostatic chuck 20 are provided in the chamber 10. The base 18 is made of a conductive material such as aluminum, and has a substantially disk shape. The central axis of the base 18 is an axis line AX.

[0043] The base 18 provides a flow path 18f therein. The flow path 18f is a flow path for a heat exchange medium. The heat exchange medium is, for example, a refrigerant. The flow path 18f is connected to a supply device 22 for the heat exchange medium. The supply device 22 is provided outside the chamber 10. The flow path 18f receives the heat exchange medium supplied from the supply device 22. The heat exchange medium supplied to the flow path 18f flows through the flow path 18f and is returned to the supply device 22.

[0044] The electrostatic chuck 20 is provided on the base 18. The substrate W is placed on and held by the electrostatic chuck 20 when being processed in the internal space 10s.

[0045] The electrostatic chuck 20 has a body and a chuck electrode. The body of the electrostatic chuck 20 is formed of a dielectric material such as aluminum oxide or aluminum nitride. The body of the electrostatic chuck 20 has a substantially disk shape. The central axis of the electrostatic chuck 20 is an axis line AX. The chuck electrode is provided within the body of the electrostatic chuck 20. The chuck electrode has a film shape. The chuck electrode is electrically connected to a DC power supply via a switch. When a voltage from the DC power supply is applied to the chuck electrode, an electrostatic attractive force is generated between the electrostatic chuck 20 and the substrate W. The generated electrostatic attractive force attracts the substrate W to the electrostatic chuck 20 and the substrate W is held by the electrostatic chuck 20.

[0046] The electrostatic chuck 20 includes a substrate mounting area. The substrate mounting area is a substantially disk-shaped area. The central axis of the substrate mounting area is an axis line AX. When the substrate W is processed in the chamber 10, it is placed on the upper surface of the substrate mounting area.

[0047] In one embodiment, the electrostatic chuck 20 may further include an edge ring mounting region. The edge ring mounting region extends in a circumferential direction around the central axis of the electrostatic chuck 20 to surround the substrate mounting region. An edge ring ER is mounted on an upper surface of the edge ring mounting region. The edge ring ER may be partially mounted on the insulating portion 17.

[0048] The plasma processing apparatus 1 may be provided with a gas supply line 24. The gas supply line 24 supplies a heat transfer gas, for example, He gas, from a gas supply mechanism to a gap between the upper surface of the electrostatic chuck 20 and the rear surface (lower surface) of the substrate W.

[0049] 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 by the upper part of the chamber body 12 via the member 32.

[0050] The upper electrode 30 may include a top plate 34 and a support 36. The lower surface of the top plate 34 defines an internal space 10s. The top plate 34 provides a plurality of gas discharge holes 34a. Each of the plurality of gas discharge holes 34a penetrates the top plate 34 in the plate thickness direction (vertical direction). The top plate 34 is made of, for example, silicon. Alternatively, the top plate 34 may have a structure in which a plasma-resistant film is provided on the surface of an aluminum member. This film may be a ceramic film, such as a film formed by anodizing or a film formed of yttrium oxide.

[0051] The support 36 detachably supports the top plate 34. The support 36 is formed of a conductive material such as aluminum. The support 36 provides a gas diffusion chamber 36a therein. The support 36 further provides a plurality of gas holes 36b. The plurality of gas holes 36b extend downward from the gas diffusion chamber 36a and communicate with the plurality of gas discharge holes 34a, respectively. The support 36 further provides a gas introduction port 36c. 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.

[0052] The gas source group 40 is connected to the gas supply pipe 38 via the valve group 41, the flow rate controller group 42, and the valve group 43. The gas source group 40, the valve group 41, the flow rate controller group 42, and the valve group 43 configure a gas supply unit. The gas source group 40 includes a plurality of gas sources. Each of the valve group 41 and the valve group 43 includes a plurality of valves (e.g., on-off valves). The flow rate controller group 42 includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers of the flow rate controller group 42 is a mass flow controller or a pressure control type flow rate controller. Each of the plurality of gas sources of the gas source group 40 is connected to the gas supply pipe 38 via a corresponding valve of the valve group 41, a corresponding flow rate controller of the flow rate controller group 42, and a corresponding valve of the valve group 43. The plasma processing apparatus 1 can supply 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 individually adjusted flow rates.

[0053] The plasma processing apparatus 1 may further include a baffle member 48. The baffle member 48 extends between the insulating portion 17 and the side wall of the chamber body 12. The baffle member 48 may be formed, for example, by coating an aluminum member with a ceramic such as yttrium oxide. The baffle member 48 provides a plurality of through holes. The space above the baffle member 48 and the space below the baffle member 48 are connected via the plurality of through holes in the baffle member 48.

[0054] The plasma processing apparatus 1 may further include an exhaust device 50. The exhaust device 50 is connected to the bottom of the chamber body 12 below the baffle member 48 via an 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 in the internal space 10s.

[0055] The plasma processing apparatus 1 further includes a high-frequency power supply 61. The high-frequency power supply 61 generates high-frequency power HF to be supplied to a high-frequency electrode to generate plasma above the substrate W supported by the substrate support 16. 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 one embodiment, the high-frequency electrode is the base 18. That is, in one embodiment, the base 18 provides a lower electrode that is a high-frequency electrode. The high-frequency power supply 61 is connected to the base 18 via a matching device 63. The matching device 63 has a matching circuit configured to match the impedance of the load side (base 18 side) of the high-frequency power supply 61 to the output impedance of the high-frequency power supply 61. In one embodiment, the high-frequency power supply 61 may be connected to the base 18 via the matching device 63 and an electrical path 71. In one embodiment, the electrical path 71 connects the bias power supply 62 to the base 18. That is, in one embodiment, the base 18 provides a lower electrode that is a bias electrode.

[0056] The bias power supply 62 is configured to provide an electric bias EB to a bias electrode of the substrate support 16 (base 18 in the example of FIG. 1 ). The electric bias EB can be used to attract ions to the substrate W.

[0057] In one embodiment, the bias power supply 62 may generate a high frequency bias power as the electric bias EB. The high frequency bias power has a second frequency. The second frequency is different from the frequency of the high frequency power HF. The second frequency may be lower than the first frequency. The second frequency is a frequency in the range of 50 kHz to 27 MHz, for example, 400 kHz. Note that, when the high frequency power supply 61 is connected to the upper electrode 30 instead of the base 18, the second frequency may be lower or higher than the first frequency, or may be the same as the first frequency.

[0058] In order to supply high frequency bias power to the bias electrode, the bias power supply 62 is connected to the bias electrode (the base 18 in the example of FIG. 1) via a matching device 64. The matching device 64 has a matching circuit configured to match the impedance of the load side of the bias power supply 62 to the output impedance of the bias power supply 62.

[0059] In another embodiment, the bias power supply 62 may be configured to periodically apply a voltage pulse (i.e., a pulsed voltage) or a voltage having an arbitrary waveform as the electric bias EB to the bias electrode (the base 18 in the example of FIG. 1). The voltage pulse may have negative polarity. The voltage pulse may be a negative DC voltage pulse. The voltage pulse is applied to the base 18 at a period defined by a second frequency. In this embodiment, the second frequency may be a frequency within a range of 1 kHz to 1 MHz. The voltage of the pulse may change during the period in which the pulse is applied to the bias electrode.

[0060] In an embodiment, the plasma processing apparatus 1 may further include a first electrode 81. The first electrode 81 is electrically coupled to the edge ring ER. The first electrode 81 may be capacitively coupled to the edge ring ER. The first electrode 81 is disposed below the edge ring ER. In an embodiment, the first electrode 81 may be provided in an edge ring mounting region of the electrostatic chuck 20. In another embodiment, the first electrode 81 may be provided in the insulating portion 17. The first electrode 81 may be directly coupled to the edge ring ER. The first electrode 81 may be a single electrode or may extend in a circumferential direction around the axis line AX. Alternatively, the first electrode 81 may include a plurality of electrodes arranged along a circumferential direction around the axis line AX. The plurality of electrodes constituting the first electrode 81 may be arranged at equal intervals.

[0061] In one embodiment, the plasma processing apparatus 1 may further include an impedance adjuster 83. The impedance adjuster 83 provides a variable impedance. The variable impedance of the impedance adjuster 83 may be controlled by a controller MC described later. In one embodiment, the impedance adjuster 83 is connected between the high-frequency electrode (the base 18 in the example of FIG. 1) and the first electrode 81. In one embodiment, the impedance adjuster 83 includes one or more variable impedance elements. The one or more variable impedance elements may include a variable capacitance capacitor. In another embodiment, the impedance adjuster 83 may include a circuit configured of a parallel connection of a plurality of series circuits. Each of the plurality of series circuits may include a series connection of a fixed impedance element and a switching element. The fixed impedance element is, for example, a fixed capacitance capacitor.

[0062] In one embodiment, the plasma processing apparatus 1 may further include a second electrode 82. The second electrode 82 is electrically coupled to the outer ring OR. The second electrode 82 may be capacitively coupled to the outer ring OR. The outer ring OR has an annular shape. The outer ring OR may be conductive. The outer ring OR is formed of, for example, silicon or silicon carbide. The outer ring OR extends radially outwardly relative to the edge ring ER. The outer ring OR is disposed such that its central axis coincides with the axis AX. In one embodiment, the outer ring OR extends to surround the edge ring ER. The outer ring OR may be placed on the substrate support 16 or on the insulating portion 17.

[0063] The second electrode 82 may be disposed below the outer ring OR as shown in FIG. 1. The second electrode 82 may be provided in or on the surface of the insulating portion 17. The second electrode 82 may be directly coupled to the outer ring OR. The second electrode 82 may be a single electrode, and may extend in a circumferential direction around the axis line AX. Alternatively, the second electrode 82 may include a plurality of electrodes arranged along a circumferential direction around the axis line AX. The plurality of electrodes constituting the second electrode 82 may be arranged at equal intervals.

[0064] In the plasma processing apparatus 1, a portion of the high frequency power HF is supplied to the outer ring OR. In one embodiment, a portion of the high frequency power HF is supplied to the outer ring OR through the second electrode 82. The outer ring OR is connected to the electrical path 71 through an impedance adjuster 84. In one embodiment, the second electrode 82 is connected to the electrical path 71 through the impedance adjuster 84. That is, the impedance adjuster 84 is connected between the electrical path 71 and the second electrode 82. The impedance adjuster 84 provides a variable impedance. The variable impedance of the impedance adjuster 84 can be controlled by the control unit MC. In one embodiment, the impedance adjuster 84 includes one or more variable impedance elements. The one or more impedance elements may include a variable capacitance capacitor. In another embodiment, the impedance adjuster 84 may include a circuit configured of a parallel connection of a plurality of series circuits. Each of the plurality of series circuits may include a series connection of a fixed impedance element and a switching element. The fixed impedance element is, for example, a fixed capacitance capacitor.

[0065] In one embodiment, the plasma processing apparatus 1 may further include a control unit MC. The control unit MC is a computer including a processor, a storage device, an input device, a display device, etc., and controls each part of the plasma processing apparatus 1. Specifically, the control unit MC executes a control program stored in the storage device, and controls each part of the plasma processing apparatus 1 based on recipe data stored in the storage device. Under the control of the control unit MC, a process specified by the recipe data is executed in the plasma processing apparatus 1.

[0066] In one embodiment, the electrical path 71 may be configured to distribute power to the base 18 uniformly in the circumferential direction about the axis AX. In one embodiment, the electrical path 71 may include a plurality of branch lines respectively connected to a plurality of positions on the base 18. The plurality of positions have an equal distance from the axis AX and are arranged at equal intervals in the circumferential direction about the axis AX. Furthermore, the plurality of branch lines of the electrical path 71 are arranged at equal intervals in the circumferential direction about the axis AX. Furthermore, the electrical lengths of the electrical path 71 for each of the plurality of positions on the base 18 are approximately equal to each other. According to this embodiment, it is possible to uniformly supply power to the base 18 via the electrical path 71.

[0067] In one embodiment, the plasma processing apparatus 1 may further include an electric path 72. The electric path 72 is an electric path for power distributed between the bias electrode (the base 18 in the example of FIG. 1) and the edge ring ER (or the first electrode 81) and supplied to the first electrode 81. The electric path 72 may include a plurality of branch lines respectively connected to a plurality of positions of the edge ring ER (or the first electrode 81). The plurality of positions have an equal distance from the axis line AX and are arranged at equal intervals in the circumferential direction about the axis line AX. In addition, the plurality of branch lines of the electric path 72 are arranged at equal intervals in the circumferential direction about the axis line AX. In addition, the electrical lengths of the electric path 72 for each of the plurality of positions of the edge ring ER (or the first electrode 81) are approximately equal to each other. According to this embodiment, it is possible to uniformly supply power to the edge ring ER via the electric path 72.

[0068] In one embodiment, the plasma processing apparatus 1 may further include an electric path 73. The electric path 73 is an electric path for power distributed between the high-frequency electrode (the base 18 in the example of FIG. 1) and the outer ring OR (or the second electrode 82) and supplied to the outer ring OR. The electric path 73 may include a plurality of branch lines respectively connected to a plurality of positions of the outer ring OR (or the second electrode 82). The plurality of positions have an equal distance from the axis line AX and are arranged at equal intervals in the circumferential direction about the axis line AX. In addition, the plurality of branch lines of the electric path 73 are arranged at equal intervals in the circumferential direction about the axis line AX. In addition, the electrical lengths of the electric path 73 for the respective positions of the outer ring OR (or the second electrode 82) are approximately equal to each other. According to this embodiment, it is possible to uniformly supply power to the outer ring OR via the electric path 73.

[0069] In one embodiment, the plasma processing apparatus 1 may further include a filter 74. The filter 74 is connected between the impedance adjuster 84 and the outer ring OR (or the second electrode 82). The filter 74 may have a frequency characteristic that selectively passes the high frequency power HF with respect to the electric bias EB. Alternatively, the filter 74 may have a frequency characteristic that selectively passes the electric bias EB with respect to the high frequency power HF. Alternatively, the pass band of the filter 74 may be changeable to any one of the band of the high frequency power HF, the band of the electric bias EB, and both bands.

[0070] Hereinafter, reference will be made to Figures 2(a), 2(b), 3(a), and 3(b) along with Figure 1. Figures 2(a) and 2(b) are each a timing chart of an example of high frequency power and an electric bias used in the plasma processing apparatus shown in Figure 1. Figures 3(a) and 3(b) are each a timing chart of another example of high frequency power and an electric bias used in the plasma processing apparatus shown in Figure 1. These figures show the power level of the high frequency power HF and the voltage level of the electric bias EB.

[0071] In Fig. 2(a), Fig. 2(b), Fig. 3(a), and Fig. 3(b), "H" of the high frequency power HF indicates that the power level of the high frequency power HF is high. "L" of the high frequency power HF indicates that the power level of the high frequency power HF is lower than the level indicated by "H". "ON" of the high frequency power HF indicates that the high frequency power HF is being supplied, and "OFF" of the high frequency power HF indicates that the supply of the high frequency power HF is stopped, i.e., the high frequency power HF is 0 (W). "ON" of the electric bias EB indicates that a voltage pulse (e.g., a negative DC voltage pulse) is being applied to the base 18. "OFF" of the electric bias EB indicates that the voltage pulse is stopped, i.e., the voltage of the electric bias EB is 0 (V).

[0072] The period CY of the electric bias EB includes a first period P1 and a second period P2. The first period P1 is a period during which the electric bias EB has a voltage equal to or greater than the average voltage of the electric bias EB in the period CY. The first period P1 is, for example, a period during which the electric bias EB has a positive or zero voltage. The second period P2 is a period during which the electric bias EB has a voltage lower than the average voltage. The second period P2 is, for example, a period during which the electric bias EB has a negative voltage. As shown in FIG. 2(a) and FIG. 2(b), the electric bias EB may be a high-frequency bias power. Alternatively, as shown in FIG. 3(a) and FIG. 3(b), the electric bias EB may include a pulse of voltage (for example, a pulse of negative DC voltage) periodically applied to the bias electrode.

[0073] In the plasma processing apparatus 1, the radio frequency power supply 61 is configured to change the power level of the radio frequency power HF in synchronization with the electric bias EB within each cycle CY of the electric bias EB. In one embodiment, the radio frequency power supply 61 may supply a pulse of the radio frequency power HF to the radio frequency electrode (the base 18 in the example of FIG. 1) and the outer ring OR during the same period within each cycle CY of the electric bias EB.

[0074] In the example shown in FIG. 2(a) and the example shown in FIG. 3(a), a pulse of high frequency power HF is supplied to the high frequency electrode (base 18 in the example of FIG. 1) and the outer ring OR in the first period P1. In the first period P1, the thickness of the sheath (plasma sheath) on the substrate W is small, and the impedance on the substrate W is small. Therefore, in the first period P1, the high frequency power HF coupled to the plasma through the substrate W is relatively large compared to the high frequency power HF coupled to the plasma around the outer ring OR. As a result, in these examples, the plasma density in the region above the center of the substrate W is relatively increased compared to the plasma density in the region above the edge of the substrate W. Therefore, according to these examples, it is possible to correct the plasma density distribution in which the plasma density is high in the region above the edge of the substrate W and low in the region above the center of the substrate W to a uniform density distribution in the radial direction. In addition, in these examples, it is possible to adjust the plasma density distribution in the radial direction in the space including the region outside the region above the edge ring ER.

[0075] In the example shown in FIG. 2(b) and the example shown in FIG. 3(b), a pulse of high frequency power HF is supplied to the high frequency electrode (base 18 in the example of FIG. 1) and the outer ring OR in the second period P2. In the second period P2, the thickness of the sheath (plasma sheath) on the substrate W is large, and the impedance on the substrate W is large. Therefore, in the second period P2, the high frequency power HF coupled to the plasma around the outer ring OR is relatively large compared to the high frequency power HF coupled to the plasma through the substrate W. As a result, in these examples, the plasma density in the region above the edge of the substrate W is increased. Therefore, in these examples, it is possible to correct the plasma density distribution, in which the plasma density is low in the region above the edge of the substrate W and the plasma density is high in the region above the center of the substrate W, to a uniform density distribution in the radial direction. In addition, in these examples, it is possible to adjust the plasma density distribution in the radial direction in the space including the region outside the region above the edge ring ER.

[0076] In the plasma processing apparatus 1, the power level of the high frequency power HF in each cycle CY is changed by the control of the high frequency power supply 61 by the control unit MC. In the plasma processing apparatus 1 of one embodiment, the supply timing of the pulse of the high frequency power HF can be set by the control of the high frequency power supply 61 by the control unit MC. In addition, the distribution ratio of the high frequency power between the high frequency electrode (base 18 in the example of FIG. 1) and the outer ring OR can be set by the control of the impedance of the impedance adjuster 84 by the control unit MC. In addition, the distribution ratio of the electric bias EB between the bias electrode (base 18 in the example of FIG. 1) and the edge ring ER can be set by the control of the impedance of the impedance adjuster 83 by the control unit MC.

[0077] The control unit MC may specify the thickness of the edge ring ER from measurements by one or more sensors or the time of use of the edge ring ER. The control unit MC may adjust the impedance of the impedance adjuster 83 according to the specified thickness of the edge ring ER so as to uniformize the height position of the interface between the plasma and the sheath in the radial direction. The control unit MC may store in advance in the storage device the relationship between the thickness of the edge ring ER and the impedance of the impedance adjuster 83 in the form of a table or a function. The control unit MC may determine the impedance of the impedance adjuster 83 from the thickness of the edge ring ER by utilizing the relationship.

[0078] The control unit MC may set the impedance of the impedance adjuster 84 so as to uniformize the distribution of plasma density in the radial direction according to the specified thickness of the edge ring ER or one or more measured values ​​measured by one or more sensors. The one or more sensors may include a sensor that measures the distribution of plasma density in the internal space 10s. The one or more sensors may include a sensor that measures the voltage of each of the substrate W, the edge ring ER, and the outer ring OR. The one or more sensors may include a sensor that measures the current flowing through each of the substrate W, the edge ring ER, and the outer ring OR. The one or more sensors may include a sensor that measures the emission intensity distribution in the internal space 10s. The control unit MC may store in advance in the storage device a relationship between the specified thickness of the edge ring ER or one or more measured values ​​measured by one or more sensors and the impedance of the impedance adjuster 84 in the form of a table or a function. The control unit MC may determine the impedance of the impedance adjuster 84 from the thickness of the edge ring ER or one or more measured values ​​measured by one or more sensors using the relationship.

[0079] According to the plasma processing apparatus 1, the distribution ratio of the electric bias EB between the bias electrode (base 18 in the example of FIG. 1) and the edge ring ER is adjusted by the impedance adjuster 83. Therefore, the level of the negative bias at the edge ring ER is adjusted by the impedance adjuster 83. This makes it possible to adjust the thickness of the sheath on the edge ring ER. Also, in the plasma processing apparatus 1, the power level of the high frequency power HF supplied to the outer ring OR is changed within each period CY of the electric bias EB. Therefore, according to the plasma processing apparatus 1, it becomes possible to adjust the distribution of plasma density in the radial direction within each period CY.

[0080] Furthermore, when a pulse of high frequency power HF is supplied to the high frequency electrode and the outer ring OR in the first period P1, the plasma density on the substrate W and the plasma density around the outer ring OR can be increased. When a pulse of high frequency power HF is supplied to the high frequency electrode and the second electrode 82 in the second period P2, the plasma density around the outer ring OR can be increased relative to the plasma density on the substrate W. Therefore, according to the plasma processing apparatus 1, it is possible to adjust the radial plasma density distribution within each cycle CY.

[0081] A plasma processing method using the plasma processing apparatus 1 will be described below. The plasma processing method includes steps (a1) and (b1). In step (a1), a high frequency power HF is supplied from a high frequency power supply 61 to a high frequency electrode (base 18 in the example of FIG. 1) in order to generate plasma from a gas in the chamber 10. In step (b1), an electric bias EB is applied from a bias power supply 62 to the bias electrode (base 18 in the example of FIG. 1). In step (a1), the high frequency power supply 61 changes the power level of the high frequency power HF in synchronization with the electric bias EB within each cycle CY.

[0082] In step (a1), the high frequency power supply 61 may supply a pulse of high frequency power HF to the high frequency electrode (the base 18 in FIG. 1) and the second electrode 82 during the same period in each cycle CY. The same period may be the first period P1 or the second period P2 in the cycle CY. At P2 It's fine.

[0083] Reference will now be made to Fig. 4. Fig. 4 is a diagram illustrating a plasma processing apparatus according to another exemplary embodiment. Differences between the plasma processing apparatus 1B illustrated in Fig. 4 and the plasma processing apparatus 1 will be described below.

[0084] The plasma processing apparatus 1B does not include an impedance adjuster 84. In addition to the high frequency power supply 61 (first high frequency power supply) that generates the high frequency power HF (first high frequency power), the plasma processing apparatus 1B further includes a high frequency power supply 91 as a second high frequency power supply. The high frequency power supply 91 is configured to generate the high frequency power HF2 (second high frequency power) that is supplied to the second electrode 82. The frequency of the high frequency power generated by the high frequency power supply 91 may be the same as or different from the frequency of the high frequency power HF.

[0085] The high frequency power supply 91 is connected to the outer ring OR via a matching unit 93 and an electrical path 75. The high frequency power supply 91 may be connected to the second electrode 82 via the matching unit 93 and the electrical path 75. The matching unit 93 has a matching circuit configured to match the impedance of the load side of the high frequency power supply 91 to the output impedance of the high frequency power supply 91.

[0086] In one embodiment, the electrical path 75 may include a plurality of branch lines respectively connected to a plurality of positions of the outer ring OR (or the second electrode 82). The plurality of positions are equally spaced from the axis line AX and are arranged at equal intervals in the circumferential direction about the axis line AX. The plurality of branch lines of the electrical path 75 are also arranged at equal intervals in the circumferential direction about the axis line AX. The electrical lengths of the electrical path 75 for each of the plurality of positions of the outer ring OR (or the second electrode 82) are approximately equal to each other. According to this embodiment, it is possible to uniformly supply power to the outer ring OR via the electrical path 75.

[0087] Hereinafter, reference will be made to (a) of FIG. 5, (b) of FIG. 5, (a) of FIG. 6, and (b) of FIG. 6 together with FIG. 4. (a) of FIG. 5 and (b) of FIG. 5 are timing charts of the first high frequency power, the second high frequency power, and the electric bias of an example used in the plasma processing apparatus shown in FIG. 4. (a) of FIG. 6 and (b) of FIG. 6 are timing charts of the first high frequency power, the second high frequency power, and the electric bias of another example used in the plasma processing apparatus shown in FIG. 4. (a) of FIG. 5, (b) of FIG. 5, (a) of FIG. 6, and (b) of FIG. 6 show the power level of the high frequency power HF (first high frequency power), the power level of the high frequency power HF2 (second high frequency power), and the voltage level of the electric bias EB.

[0088] In FIG. 5(a), FIG. 5(b), FIG. 6(a), and FIG. 6(b), "H" of the high frequency power HF indicates that the power level of the high frequency power HF is high. "L" of the high frequency power HF indicates that the power level of the high frequency power HF is lower than the level indicated by "H". "ON" of the high frequency power HF indicates that the high frequency power HF is being supplied, and "OFF" of the high frequency power HF indicates that the supply of the high frequency power HF is stopped, i.e., the high frequency power HF is 0 (W). In these figures, "H" of the high frequency power HF2 indicates that the power level of the high frequency power HF2 is high, and "L" of the high frequency power HF2 indicates that the power level of the high frequency power HF2 is lower than the level indicated by "H". "ON" of the high frequency power HF2 indicates that the high frequency power HF2 is being supplied, and "OFF" of the high frequency power HF2 indicates that the supply of the high frequency power HF2 is stopped, i.e., the high frequency power HF2 is 0 (W). Moreover, the "ON" state of the electric bias EB indicates that a voltage pulse (e.g., a negative DC voltage pulse) is being applied to the base 18. Moreover, the "OFF" state of the electric bias EB indicates that the voltage pulse is stopped, that is, the voltage of the electric bias EB is 0 (V).

[0089] Similar to the electric bias EB described above with respect to the plasma processing apparatus 1, in the plasma processing apparatus 1B, the first period P1 is a period during which the electric bias EB has a voltage equal to or greater than the average voltage of the electric bias EB within the period CY. The first period P1 is, for example, a period during which the electric bias EB has a positive or zero voltage. The second period P2 is a period during which the electric bias EB has a voltage lower than the average voltage. The second period P2 is, for example, a period during which the electric bias EB has a negative voltage. As shown in FIG. 5(a) and FIG. 6(a), the electric bias EB may be a high-frequency bias power. Alternatively, as shown in FIG. 5(b) and FIG. 6(b), the electric bias EB may include a voltage pulse (e.g., a negative DC voltage pulse) periodically applied to the base 18.

[0090] In the plasma processing apparatus 1B, the radio frequency power supply 91 is configured to change the power level of the radio frequency power HF2 in synchronization with the electric bias EB within each cycle CY of the electric bias EB. In one embodiment, the radio frequency power supply 91 may be configured to supply a pulse of the radio frequency power HF2 to the outer ring OR during the same period within each cycle CY.

[0091] In the example shown in Fig. 5(a) and the example shown in Fig. 5(b), a pulse of high frequency power HF2 is supplied to the outer ring OR in the first period P1. In these examples, as shown by solid lines in Fig. 5(a) and Fig. 5(b), a pulse of high frequency power HF may be supplied to the high frequency electrode (the base 18 in the example of Fig. 4) and the edge ring ER in the second period P2. Alternatively, in these examples, as shown by dashed lines in Fig. 5(a) and Fig. 5(b), a continuous wave of high frequency power HF may be supplied to the high frequency electrode (the base 18 in the example of Fig. 4) and the edge ring ER in both the first period P1 and the second period P2.

[0092] In the example shown in FIG. 5(a) and the example shown in FIG. 5(b), the pulse of the high frequency power HF2 supplied in the first period P1 increases the plasma density around the outer ring OR in the first period P1. Also, a relatively large portion of the high frequency power HF supplied in the second period P2 is coupled to the plasma around the outer ring OR. As a result, in these examples, the plasma density in the region above the edge of the substrate W is relatively increased compared to the plasma density in the region above the center of the substrate W. Therefore, according to these examples, it is possible to correct the plasma density distribution, in which the plasma density is low in the region above the edge of the substrate W and the plasma density is high in the region above the center of the substrate W, to a uniform density distribution in the radial direction. Also, in these examples, it is possible to adjust the plasma density distribution in the radial direction in the space including the region outside the region above the edge ring ER.

[0093] In the example shown in FIG. 6(a) and the example shown in FIG. 6(b), a pulse of high frequency power HF2 is supplied to the outer ring OR in the first period P1. In these examples, a pulse of high frequency power HF is supplied to the high frequency electrode (the base 18 in the example of FIG. 4) and the edge ring ER in the first period P1. In the first period P1, the thickness of the sheath (plasma sheath) on the substrate W is small, and the impedance on the substrate W is small. Therefore, a relatively large amount of high frequency power HF is coupled to the plasma through the center of the substrate W. As a result, in these examples, the plasma density is high in the region above the center of the substrate W. Therefore, in these examples, it is possible to correct the plasma density distribution, in which the plasma density is high in the region above the edge of the substrate W and the plasma density is low in the region above the center of the substrate W, to a uniform density distribution in the radial direction. In these examples, the high frequency power HF2 supplied in the first period P1 makes it possible to adjust the plasma density distribution in the radial direction in the space including the region outside the region above the edge ring ER.

[0094] In the plasma processing apparatus 1B, the supply of the high frequency power HF in each cycle CY is performed by the control of the high frequency power supply 61 by the control unit MC. Moreover, the change in the power level of the high frequency power HF2 in each cycle CY is performed by the control of the high frequency power supply 91 by the control unit MC. Moreover, in the plasma processing apparatus 1B, the distribution ratio of the electric bias EB between the high frequency electrode (base 18 in the example of FIG. 4) and the edge ring ER can be set by the control of the impedance of the impedance adjuster 83 by the control unit MC. Similar to the control unit MC of the plasma processing apparatus 1, the control unit MC may determine the impedance of the impedance adjuster 83 from the thickness of the edge ring ER.

[0095] In the plasma processing apparatus 1B, the control unit MC may adjust the settings of the high frequency power supply 61 and the high frequency power supply 91 so as to uniformize the distribution of plasma density in the radial direction according to the specified thickness of the edge ring ER or one or more measured values ​​measured by one or more sensors. That is, the control unit MC may adjust the supply timing and power level of the high frequency power HF and the supply timing and power level of the high frequency power HF2. The one or more sensors may include a sensor that measures the distribution of plasma density in the internal space 10s. The one or more sensors may include a sensor that measures the voltage of each of the substrate W, the edge ring ER, and the outer ring OR. The one or more sensors may include a sensor that measures the current flowing through each of the substrate W, the edge ring ER, and the outer ring OR. The one or more sensors may include a sensor that measures the emission intensity distribution in the internal space 10s. The control unit MC may store in advance in its storage device the relationship between the specified thickness of the edge ring ER or one or more measured values ​​measured by one or more sensors and the settings of the high frequency power supply 61 and the high frequency power supply 91 in the form of a table or a function. The controller MC may use this relationship to determine the settings of the high frequency power supplies 61 and 91 from the thickness of the edge ring ER or one or more measured values ​​measured by one or more sensors.

[0096] In the examples shown in Fig. 5(a), Fig. 5(b), Fig. 6(a), and Fig. 6(b), the power level of the high frequency power HF2 in the second period P2 may be set to a level indicated by "L" instead of 0. In the second period P2, the plasma density around the outer ring OR tends to decrease relatively significantly. Therefore, by supplying the high frequency power HF2 to the outer ring OR in the second period P2 as well, it is possible to suppress the fluctuation of the plasma density distribution in the radial direction.

[0097] In the plasma processing apparatus 1B, the distribution ratio of the electric bias EB between the high frequency electrode and the edge ring ER is adjusted by the impedance adjuster 83. Thus, the level of the negative bias in the edge ring ER is adjusted. This makes it possible to adjust the thickness of the sheath on the edge ring ER. Also, the power level of the high frequency power HF2 supplied to the outer ring OR in each period CY is changed. Thus, according to the plasma processing apparatus 1B, it becomes possible to adjust the distribution of plasma density in the radial direction in each period CY. Also, in the plasma processing apparatus 1B, during the first period P1 in which the sheath on the substrate W is thin, the high frequency power HF2 supplied to the outer ring OR and the high frequency power HF supplied to the high frequency electrode are adjusted. HF and The radial distribution of plasma density is adjusted within each cycle CY by the ratio of

[0098] A plasma processing method using the plasma processing apparatus 1B will be described below. The plasma processing method includes steps (a2), (b2), and (c2). In step (a2), a high frequency power HF is supplied from a high frequency power supply 61 to a high frequency electrode (the base 18 in the example of FIG. 4) to generate plasma from a gas in the chamber 10. In step (b2), an electric bias EB is applied from a bias power supply 62 to a bias electrode (the base 18 in the example of FIG. 4). In step (c2), a high frequency power HF2 is supplied from a high frequency power supply 91 to an outer ring OR. In step (c2), the high frequency power supply 91 changes the power level of the high frequency power HF2 in synchronization with the electric bias EB within each cycle CY.

[0099] In step (c2), the high frequency power supply 61 may supply a pulse of high frequency power HF2 to the second electrode 82 during the same period in each cycle CY. The same period may be a first period P1 in the cycle CY.

[0100] Reference will now be made to Fig. 7. Fig. 7 is a schematic diagram of a plasma processing apparatus according to yet another exemplary embodiment. Differences between the plasma processing apparatus 1C and the plasma processing apparatus 1B shown in Fig. 7 will be described below.

[0101] The plasma processing apparatus 1C does not include the impedance adjuster 83. In the plasma processing apparatus 1C, a bias power supply 92 is connected to the edge ring ER (or the first electrode 81) via a matching device 94 and an electrical path 72. The bias power supply 92 is a power supply similar to the bias power supply 62. The matching device 94 includes a matching circuit for matching the impedance on the load side of the bias power supply 92 to the output impedance of the bias power supply 92.

[0102] In the plasma processing apparatus 1C, the control unit MC may specify the thickness of the edge ring ER from measurements by one or more sensors or the usage time of the edge ring ER. The control unit MC may set the level of the electric bias generated by the bias power supply 92 so as to uniformize the height position of the interface between the plasma and the sheath in the radial direction according to the specified thickness of the edge ring ER. The control unit MC may store in advance in the storage device the relationship between the thickness of the edge ring ER and the electric bias generated by the bias power supply 92 in the form of a table or a function. The control unit MC may determine the level of the electric bias generated by the bias power supply 92 from the thickness of the edge ring ER by utilizing the relationship.

[0103] In the plasma processing apparatus 1C, a separate high-frequency power supply that generates high-frequency power may be electrically connected to the edge ring ER (or the first electrode 81) via a matching box.

[0104] Reference will now be made to FIG. 8. FIG. 8 is a diagram that illustrates a schematic diagram of a plasma processing apparatus according to yet another exemplary embodiment. Hereinafter, differences between the plasma processing apparatus 1D illustrated in FIG. 8 and the plasma processing apparatus 1C will be described. In the plasma processing apparatus 1D, a bias electrode 21 is provided in an electrostatic chuck 20. The bias electrode 21 may also function as a chuck electrode, or may be an electrode separate from the chuck electrode. In the plasma processing apparatus 1D, a bias power supply 62 is connected to the bias electrode 21 via an electrical path separate from the electrical path 71.

[0105] Although various exemplary embodiments have been described above, the present invention is not limited to the above-described exemplary embodiments, and various additions, omissions, substitutions, and modifications may be made. In addition, elements in different embodiments can be combined to form other embodiments.

[0106] For example, in another embodiment, the high frequency power supply 61 may be connected to the upper electrode 30, rather than the base 18, via a matching box 63. In this case, the upper electrode 30 is used as the high frequency electrode.

[0107] In yet another embodiment, when the high-frequency power supply 61 is connected to the base 18 via the electrical path 71, the impedance adjuster 83 may be connected between the electrical path 71 and the edge ring ER (or the first electrode 81).

[0108] In yet another embodiment, the outer ring OR may be disposed at a position higher than the position of the edge ring ER in the vertical direction. In yet another embodiment, the outer ring OR may be disposed so as to surround the upper electrode 30. In this case, the outer ring OR may be disposed within the member 32.

[0109] In yet another embodiment, the impedance adjuster 84 may be connected between the base 18 and the outer ring OR (or the second electrode 82).

[0110] In yet another embodiment, a separate bias power supply may be connected to the outer ring OR (or the second electrode 82) via electrical path 75. The separate bias power supply may generate radio frequency bias power supplied to the outer ring OR, or may periodically generate a pulsed voltage or a voltage having an arbitrary waveform that is applied to the outer ring OR.

[0111] From the foregoing, it will be understood that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the appended claims. [Explanation of symbols]

[0112] 1...plasma processing apparatus, 10...chamber, 16...substrate support, 18...base, 61...high frequency power supply, 62...bias power supply, ER...edge ring, 81...first electrode, 83...impedance adjuster, OR...outer ring, 82...second electrode.

Claims

1. A chamber; a substrate support having a bias electrode; a radio frequency power supply that generates radio frequency power that is supplied to a radio frequency electrode to generate a plasma above a substrate supported by the substrate support within the chamber; a bias power supply connected to the bias electrode via an electrical path; Equipped with an edge ring mounted on the substrate support is electrically connected to the bias power supply via an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to a separate bias power supply; an outer ring extending radially outwardly of the edge ring, electrically connected to the RF power source to receive a portion of the RF power; The high frequency power supply is configured to change the power level of the high frequency power in synchronization with the electric bias within each period of the electric bias output from the bias power supply to the bias electrode. Plasma processing equipment.

2. a first electrode electrically coupled to the edge ring; a second electrode electrically coupled to the outer ring; Further comprising: the impedance adjuster provides a variable impedance between the bias electrode and the first electrode or between the electrical path and the first electrode; the outer ring receives a portion of the high frequency power or another high frequency power from another high frequency power source via the second electrode; The plasma processing apparatus according to claim 1 .

3. 3. The plasma processing apparatus according to claim 1, wherein the high frequency power supply is configured to supply a pulse of the high frequency power to the high frequency electrode and the outer ring during the same period in each cycle of the electrical bias.

4. 4. The plasma processing apparatus of claim 3, wherein the same period is a first period during which the electrical bias has a voltage equal to or greater than an average voltage of the electrical bias within the period or a second period during which the electrical bias has a voltage lower than the average voltage within the period.

5. the substrate support includes a base and an electrostatic chuck provided on the base; the base provides a lower electrode which is the bias electrode; the lower electrode is the radio frequency electrode, the high frequency power source is electrically connected to the lower electrode via the electrical path; The plasma processing apparatus according to any one of claims 1 to 4.

6. The plasma processing apparatus of claim 5 , further comprising an impedance adjuster that provides a variable impedance between the electrical path and the outer ring or between the lower electrode and the outer ring.

7. a filter connected between the impedance adjuster and the outer ring to provide a variable impedance between the electrical path and the outer ring or between the lower electrode and the outer ring; the filter has a frequency characteristic that selectively passes the high frequency power with respect to the electric bias supplied from the bias power supply to the lower electrode. The plasma processing apparatus according to claim 6 .

8. the substrate support includes a base and an electrostatic chuck provided on the base; the bias electrode is provided in the electrostatic chuck, the base provides a lower electrode which is the high-frequency electrode; The high frequency power source is electrically connected to the lower electrode. The plasma processing apparatus according to any one of claims 1 to 4.

9. 9. The plasma processing apparatus of claim 8, further comprising an impedance adjuster that provides a variable impedance between an electrical path connecting the high frequency power supply to the lower electrode and the outer ring, or between the lower electrode and the outer ring.

10. A chamber; a substrate support having a bias electrode; a first high frequency power supply generating a first high frequency power supplied to a high frequency electrode to generate a plasma above a substrate supported by the substrate support in the chamber; a bias power supply connected to the bias electrode via an electrical path; a second RF power supply configured to generate a second RF power supplied to an outer ring, the outer ring extending radially outwardly from an edge ring mounted on the substrate support; Equipped with the edge ring is electrically connected to the bias power supply through an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to a separate bias power supply; A plasma processing apparatus, wherein the second high frequency power supply is configured to change the power level of the second high frequency power in synchronization with the electric bias within each period of the electric bias output from the bias power supply to the bias electrode.

11. a first electrode electrically coupled to the edge ring; a second electrode electrically coupled to the outer ring; Further comprising: the impedance adjuster provides a variable impedance between the bias electrode and the first electrode or between the electrical path and the first electrode; the outer ring receives the second high frequency power via the second electrode; The plasma processing apparatus according to claim 10.

12. the substrate support includes a base and an electrostatic chuck provided on the base; the base provides a lower electrode which is the bias electrode; the lower electrode is the radio frequency electrode, the first high frequency power supply is electrically connected to the lower electrode via the electrical path; The plasma processing apparatus according to claim 10 or 11.

13. the substrate support includes a base and an electrostatic chuck provided on the base; the bias electrode is provided in the electrostatic chuck, the base provides a lower electrode which is the high-frequency electrode; the first high frequency power supply is electrically connected to the lower electrode; The plasma processing apparatus according to claim 10 or 11.

14. The plasma processing apparatus of any one of claims 10 to 13, wherein the second high frequency power supply is configured to supply a pulse of the second high frequency power to the outer ring during the same period within each cycle of the electrical bias.

15. each period of the electrical bias includes a first period during which the electrical bias has a voltage equal to or greater than an average voltage of the electrical bias within the period and a second period during which the electrical bias has a voltage less than the average voltage within the period; The same period of time is the first period of time. The plasma processing apparatus according to claim 14.

16. 16. The plasma processing apparatus of claim 15, wherein the first high frequency power supply supplies a continuous wave of the first high frequency power in both the first period and the second period, or supplies a pulse of the first high frequency power in the second period.

17. The plasma processing apparatus of claim 15 , wherein the first high frequency power supply supplies a pulse of the first high frequency power during the first period.

18. 18. The plasma processing apparatus of claim 1, wherein the outer ring extends so as to surround the edge ring.

19. The plasma processing apparatus according to any one of claims 1 to 18, wherein the bias power supply is configured to supply high-frequency bias power to the bias electrode, or to periodically apply a pulsed voltage or a voltage having an arbitrary waveform to the bias electrode.

20. (a1) supplying radio frequency power from a radio frequency power source to a radio frequency electrode to generate a plasma above a substrate supported by a substrate support in a chamber of a plasma processing apparatus; (b1) applying an electric bias from a bias power supply to a bias electrode of the substrate support; Including, The plasma processing apparatus includes: The chamber; The substrate support; The high frequency power source; the bias power supply connected to the bias electrode via an electrical path; Equipped with an edge ring mounted on the substrate support is electrically connected to the bias power supply via an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to a separate bias power supply; an outer ring extending radially outwardly of the edge ring, electrically connected to the RF power source to receive a portion of the RF power; In the (a1), the high frequency power supply changes a power level of the high frequency power in synchronization with the electric bias within each period of the electric bias output from the bias power supply to the bias electrode. Plasma treatment method.

21. 21. The plasma processing method according to claim 20, wherein in (a1), the high frequency power supply supplies the pulses of the high frequency power to the high frequency electrode and the outer ring during the same period in each cycle of the electrical bias.

22. 22. The plasma processing method of claim 21, wherein the same period is a first period during which the electrical bias has a voltage equal to or greater than an average voltage of the electrical bias within the period or a second period during which the electrical bias has a voltage less than the average voltage within the period.

23. (a2) supplying a first high frequency power from a first high frequency power source to a high frequency electrode to generate a plasma above a substrate supported by a substrate support in a chamber of the plasma processing apparatus; (b2) applying an electric bias from a bias power supply to a bias electrode of the substrate support; (c2) supplying a second high frequency power from a second high frequency power supply to the outer ring; Including, The plasma processing apparatus includes: The chamber; The substrate support; The first high frequency power source; the bias power supply connected to the bias electrode via an electrical path; The second high frequency power source; Equipped with an edge ring mounted on the substrate support is electrically connected to the bias power supply via an impedance adjuster that provides a variable impedance between the bias electrode and the edge ring or between the electrical path and the edge ring, or is electrically connected to a separate bias power supply; the outer ring extends radially outwardly relative to the edge ring; In the (c2), the second high frequency power supply changes a power level of the second high frequency power in synchronization with the electric bias within each period of the electric bias. Plasma treatment method.

24. 24. The plasma processing method of claim 23, wherein in (c2), the second high frequency power supply supplies a pulse of the second high frequency power to the outer ring during a same period in each cycle of the electrical bias.

25. each period of the electrical bias includes a first period during which the electrical bias has a voltage equal to or greater than an average voltage of the electrical bias within the period and a second period during which the electrical bias has a voltage less than the average voltage within the period; The same period of time is the first period of time. The plasma processing method according to claim 24.

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