Patent ID: 12243723

DETAILED DESCRIPTION

Hereinafter, various exemplary embodiments will be described.

In an exemplary embodiment, a plasma processing apparatus is provided. The plasma processing apparatus is provided with a chamber, an electrostatic chuck, a first feed line, and a second feed line. The electrostatic chuck includes a first region on which a substrate is placed and a second region on which an edge ring is placed. The first region includes a first electrode provided therein. The second region including a second electrode provided therein. The first feed line connects the first electrode and a bias power supply generating a pulse of a voltage applied to the first electrode to each other. The second feed line connects the second electrode and the bias power supply or another bias power supply generating a pulse of the voltage applied to the second electrode to each other. The second feed line includes one or more sockets and one or more feed pins. The one or more feed pins have flexibility in a radial direction thereof and are fitted into the one or more sockets.

Since each of one or more feed pins of a second feed line has flexibility in a radial direction thereof, the feed pin is reduced in diameter by being fitted into the corresponding socket. Accordingly, each of the one or more feed pins of the second feed line is held by the corresponding socket to reliably come into contact with the corresponding socket. Therefore, according to the above embodiment, it is possible to stably supply the pulse of a voltage, which is bias energy, to an edge ring.

In an exemplary embodiment, the second feed line may include a plurality of sockets as the one or more sockets and may include a plurality of feed pins fitted into the plurality of sockets, respectively, as the one or more feed pins. The second feed line may include a common line and a plurality of branch lines. The plurality of branch lines are branched from the common line and connected to the second electrode. Each of the plurality of branch lines includes one of the plurality of sockets and one of the plurality of feed pins.

In an exemplary embodiment, the first feed line may include a socket and a feed pin. The feed pin of the first feed line may have flexibility in a radial direction thereof and may be fitted into the socket of the first feed line.

In an exemplary embodiment, the plasma processing apparatus may further comprise a base and a feed pipe. The electrostatic chuck is provided on the base. The feed pipe is configured to transmit radio-frequency power to the base and extends in a vertical direction below the base. The common line and the first feed line extend upward through an inner hole of the feed pipe.

In an exemplary embodiment, the second feed line may include an annular member having conductivity. The common line may be connected to the annular member. The first feed line may extend upward through an inner hole of the annular member. The plurality of branch lines may be connected between the annular member and the second electrode, and may extend in a radial direction from the annular member.

In an exemplary embodiment, the plurality of branch lines may have substantially the same length.

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

FIG.1is a view schematically illustrating a plasma processing apparatus according to an exemplary embodiment. The plasma processing apparatus1illustrated inFIG.1includes a chamber10. The chamber10provides an internal space10stherein. The internal space10scan be depressurized. Plasma is generated in the internal space10s.

The chamber10may include a chamber body12and a top portion14. The chamber body12configures a side wall and a bottom portion of the chamber10. The chamber body12has a substantially cylindrical shape. A central axis of the chamber body12substantially coincides with an axis AX that extends in the vertical direction. The chamber body12is electrically grounded. The chamber body12is formed of, for example, aluminum. A corrosion-resistant film is formed on the surface of the chamber body12. The corrosion-resistant film is formed of, for example, a material such as aluminum oxide or yttrium oxide.

An opening12pis formed on the side wall of the chamber10. The opening12pis provided by the chamber body12. The opening12pis openable and closable by a gate valve12g. A substrate W passes through the opening12pwhen being transferred between the internal space10sand the outside of the chamber10.

The chamber body12may include a first member12aand a second member12b. The first member12ahas a substantially cylindrical shape. The first member12aconfigures the bottom portion and a part of the side wall of the chamber10. The second member12bhas a substantially cylindrical shape. The second member12bis provided on the first member12a. The second member12bconfigures another part of the side wall of the chamber10. The second member12bprovides an opening12p.

The plasma processing apparatus1further includes a substrate support16. The substrate support16is provided in the internal space10s. The substrate support16is configured to support the substrate W placed thereon. A bottom plate17is provided below the substrate support16. The bottom plate17is supported by the bottom portion of the chamber10, for example, the first member12a. A support18extends upward from the bottom plate17. The support18has a substantially cylindrical shape. The support18is formed of, for example, an insulating material such as quartz. The substrate support16is mounted on the support18and is supported by the support18.

The substrate support16includes a base20and an electrostatic chuck22. The base20has a substantial disk shape. A central axis of the base20substantially coincides with the axis AX. The base20is formed of a conductor such as aluminum. A flow channel20fis formed in the base20. The flow channel20fextends, for example, in a spiral shape. Refrigerant is supplied to the flow channel20ffrom the chiller unit26. The chiller unit26is provided outside the chamber10. The chiller unit26supplies, for example, a liquid refrigerant to the flow channel20f. The refrigerant supplied to the flow channel20fflows through the flow channel20fand is returned to the chiller unit26.

The electrostatic chuck22is provided on the base20. The electrostatic chuck22has a substantial disk shape. The electrostatic chuck22is configured to hold the substrate W placed thereon by electrostatic attraction. Additionally, the electrostatic chuck22is configured to support an edge ring ER placed thereon. The edge ring ER is formed of, for example, silicon, quartz, or silicon carbide. The edge ring ER is used to improve the in-plane uniformity of plasma processing with respect to the substrate W. The substrate W is disposed in a region surrounded by the edge ring ER and on the electrostatic chuck22.

The substrate support16may further include a ring27, a tubular portion28, and a tubular portion29. The ring27is provided between the edge ring ER and the base20. The ring27is formed of an insulating material. The tubular portion28extends along the outer peripheries of the base20, the ring27, and the support18. The tubular portion28is provided on the tubular portion29. The tubular portion28is formed of an insulating material having corrosion resistance. The tubular portion28is formed of, for example, quartz. The tubular portion29extends along the outer periphery of the support18. The tubular portion29is formed of an insulating material having corrosion resistance. The tubular portion29is formed of, for example, quartz.

The top portion14is provided to close an upper end opening of the chamber10. The top portion14includes an upper electrode30. The top portion14may further include a member32and a member34. The member32is a substantially annular plate and is formed of a metal such as aluminum. The member32is provided on the side wall of the chamber10via a member58described below. That is, the member32is provided on the member58. The member34is provided between the upper electrode30and the member32. The member34extends in a circumferential direction with respect to the axis AX. The member34is formed of an insulating material such as quartz. The upper electrode30is disposed via the member34in an opening defined by the member32. The upper electrode30is supported by the member32via the member34.

The upper electrode30includes a ceiling plate36and a support38. The ceiling plate36has a substantial disk shape. The ceiling plate36is in contact with the internal space10s. A plurality of gas discharge holes36hare formed on the ceiling plate36. The plurality of gas discharge holes36hpenetrate the ceiling plate36in a plate thickness direction (vertical direction). The ceiling plate36is formed of silicon, aluminum oxide, or quartz. Alternatively, the ceiling plate36may be configured by forming a corrosion-resistant film on the surface of a member made of a conductor such as aluminum. The corrosion-resistant film is formed of for example, a material such as aluminum oxide or yttrium oxide.

The support38is provided on the ceiling plate36. The support38supports the ceiling plate36in a detachable manner. The support38is formed of for example, aluminum. A flow channel38fis formed in the support38. The flow channel38fextends, for example, in a spiral shape in the support38. Refrigerant is supplied to the flow channel38ffrom the chiller unit40. The chiller unit40is provided outside the chamber10. The chiller unit40supplies a liquid refrigerant (for example, cooling water) to the flow channel38f. The refrigerant supplied to the flow channel38fflows through the flow channel38fand is returned to the chiller unit40.

A gas diffusion chamber38dis formed inside the support38. A plurality of holes38hare formed in the support38. The plurality of holes38hextend downward from the gas diffusion chamber38dand are connected to the plurality of gas discharge holes36h, respectively. The support38is provided with a port38p. The port38pis connected to the gas diffusion chamber38d. A gas source group41is connected to the port38pvia a valve group42, a flow rate controller group43, and a valve group44.

The gas source group41includes a plurality of gas sources. Each of the valve group42and the valve group44includes a plurality of valves. The flow rate controller group43includes a plurality of flow rate controllers. Each of the plurality of flow rate controllers is a mass flow controller or a pressure-controlled flow rate controller. Each of the plurality of gas sources of the gas source group41is connected to the port38pvia the corresponding valve of the valve group44, the corresponding flow rate controller of the flow rate controller group43, and the corresponding valve of the valve group42. In the plasma processing apparatus1, gas from each of one or more gas sources selected from the plurality of gas sources in the gas source group41is supplied to the gas diffusion chamber38d. The gas supplied to the gas diffusion chamber38dis supplied to the internal space10sfrom the plurality of gas discharge holes36h.

The plasma processing apparatus1further includes a member58. The member58is partially provided in the internal space10s. That is, a part of the member58is exposed to plasma in the internal space10s. The member58extends from the internal space10stoward the outside of the chamber10and is exposed to a space outside the chamber10.

The member58extends along an inner wall surface of the chamber10to prevent the accumulation of by-products resulting from the plasma processing on the inner wall surface of the chamber10. Specifically, the member58extends along the inner wall surface of the chamber body12or the inner wall surface of the second member12b. The member58has a substantially cylindrical shape. The member58may be configured by forming a corrosion-resistant film on the surface of a member made of a conductor such as aluminum. The corrosion-resistant film is formed of a material such as aluminum oxide or yttrium oxide.

The member58is held between the chamber body12and the top portion14. For example, the member58is held between the second member12bof the chamber body12and the member32of the top portion14.

The plasma processing apparatus1may further include a spacer59. The spacer59has a plate shape and extends in the circumferential direction around the axis AX. The spacer59is provided between the member58and the chamber10. The spacer59is formed of, for example, a conductor. The spacer59may be formed of a material having a thermal conductivity lower than that of aluminum. The spacer59may be formed of, for example, stainless steel. The spacer59may be formed of a material other than the stainless steel as long as a material having a thermal conductivity lower than that of aluminum is provided. Alternatively, the spacer59may be formed of aluminum.

The spacer59is provided between the member58and the second member12b. The spacer59and the second member12bare fixed to the first member12aby using a screw60a. The screw60apenetrates the spacer59and the second member12band is screwed into a screw hole of the first member12a. The member58is fixed to the spacer59by using a screw60b. The screw60bpenetrates the member58and is screwed into the screw hole of the spacer59.

The plasma processing apparatus1may further include a heater unit62. The heater unit62includes a main body62mand a heater62h. The heater62his configured to heat the member58. The heater62hcan be a resistance beating element. The heater62his provided in the main body62m. The main body62mis in thermal contact with the member58. The main body62mis in physical contact with the member58. The main body62mis formed of a conductor such as aluminum. The heater62his configured to heat the member58via the main body62m.

The main body62mis a substantially annular plate and extends in the circumferential direction to surround the upper electrode30. In an embodiment, the top portion14further includes a member56. The member56is a substantially annular plate. The member56extends in the circumferential direction in a region radially outside the ceiling plate36. The radial direction is a radial direction with respect to the axis AX. The heater unit62is provided between the member56and the member32and between the member34and the member58.

A baffle member72is provided between the member58and the support18. In an embodiment, the baffle member72has a substantially cylindrical shape. An upper end of the baffle member72is formed in a flange shape. A lower end of the baffle member72is formed in a substantially annular shape and extends radially inward. An outer edge of the upper end of the baffle member72is coupled to a lower end of the member58. An inner edge of the lower end of the baffle member72is held between the tubular portion29and the bottom plate17. The baffle member72is formed of a plate made of a conductor such as aluminum. A corrosion-resistant film is formed on the surface of the baffle member72. The corrosion-resistant film is formed of, for example, a material such as aluminum oxide or yttrium oxide. A plurality of through-holes are formed in the baffle member72.

The internal space10sincludes an exhaust region that extends below the baffle member72. An exhaust device74is connected to the exhaust region. The exhaust device74includes a pressure regulator such as an automatic pressure control valve and a decompression pump such as a turbo molecular pump.

An opening58pis formed in the member58. The opening58pis formed in the member58to face the opening12p. The substrate W passes through the openings12pand58pwhen being transferred between the internal space10sand the outside of the chamber10.

The plasma processing apparatus1may further include a shutter mechanism76. The shutter mechanism76is configured to open and close the opening58p. The shutter mechanism76has a valve76vand a shaft76s. The shutter mechanism76may further include a tubular body76aand a driver76d.

The valve76vcloses the opening58pin a state in which the valve76vis disposed in the opening58p. The valve76vis supported by the shaft76s. That is, the shaft76sis coupled to the valve76v. The shaft76sextends downward from the valve76v.

The tubular body76ahas a tubular shape. The tubular body76ais directly or indirectly fixed to the chamber body12. The shaft76sis movable up and down through the inside of the tubular body76a. The driver76dgenerates power for moving the shaft76sup and down. The driver76dincludes, for example, a motor.

In an embodiment, the plasma processing apparatus1may further include a controller80. The controller80is configured to control each part of the plasma processing apparatus1. The controller80is, for example, a computer device. The controller80has a processor, a storage unit, an input device such as a keyboard, a display device, and an input and output interface for signals. A control program and recipe data are stored in the storage unit. The processor executes the control program and sends a control signal to each unit of the plasma processing apparatus1via the input and output interface in accordance with the recipe data.

Hereinafter, the substrate support16of the plasma processing apparatus1and the configuration related thereto will be described in detail. In the following description, reference will be made toFIGS.2and3in addition toFIG.1.FIG.2is a cross-sectional view of the substrate support of the plasma processing apparatus according to an exemplary embodiment.FIG.3is a partially enlarged cross-sectional view of the substrate support of the plasma processing apparatus according to an exemplary embodiment.

As described above, in an embodiment, the substrate support16includes the base20. A feed pipe57extends downward below the base20. The feed pipe57is a pipe formed of a conductor. A central axis of the feed pipe57substantially coincides with the axis AX. An upper end of the feed pipe57is connected to the base20.

The plasma processing apparatus1further includes a radio-frequency power supply51. The radio-frequency power supply51is connected to the feed pipe57via a matcher51mand is connected to the base20via the feed pipe57. The radio-frequency power supply51is a power supply configured to generate radio-frequency power for plasma generation. The frequency of the radio-frequency power generated by the radio-frequency power supply51is, for example, a frequency of 13.56 MHz or more and 150 MHz or less. The matcher51mhas a matching circuit for matching the impedance of a load side (base20side) of the radio-frequency power supply51with the output impedance of the radio-frequency power supply51. In another embodiment, the radio-frequency power supply51may be connected to the upper electrode30via the matcher51minstead of the base20.

As described above, the electrostatic chuck22is provided on the base20. The electrostatic chuck22provides a first region22aand a second region22b. The first region22ais configured to support the substrate W placed on thereon. The second region22bis configured to support the edge ring ER placed thereon. The first region22ais a substantially circular region in a plan view, and a central axis thereof substantially coincides with the axis AX. The second region22bis a substantially annular region in a plan view and extends in the circumferential direction to surround the first region22a.

The electrostatic chuck22includes a dielectric portion22m. The dielectric portion22mis formed of ceramic such as aluminum oxide and aluminum nitride. The dielectric portion22mhas a substantial disk shape. A central region of the dielectric portion22mconfigures the first region22a, and a peripheral region of the dielectric portion22mconfigures the second region22b.

The first region22aincludes a chuck electrode224. The chuck electrode224is a film formed of a conductive material and is provided in the dielectric portion22min the first region22a. The chuck electrode224may have a substantially circular shape in a plan view. A DC power supply52is electrically connected to the chuck electrode224via a filter52f. The filter52fis a low-pass filter. When a DC voltage from the DC power supply52is applied to the chuck electrode224, an electrostatic attraction force is generated between the first region22aand the substrate W placed on the first region22a. The substrate W is attracted to the first region22aby the generated electrostatic attraction force and is held by the electrostatic chuck22on the first region22a.

The first region22afurther includes a first electrode221. The first electrode221is a film formed of a conductive material. The first electrode221is provided in the dielectric portion22min the first region22a. The first electrode221may be provided such that the chuck electrode224is located between an upper surface of the first region22aand the first electrode221. The first electrode221may have a substantially circular shape in a plan view.

The plasma processing apparatus1further includes a first feed line81. The first feed line81connects a bias power supply54and the first electrode221to each other. Details of the first feed line81will be described below.

The bias power supply54generates a pulse of a voltage applied to the first electrode221as bias energy to draw ions into the substrate W from the plasma generated in the chamber10. The pulse of the voltage may be a negative pulse of the voltage or a positive pulse of the voltage. The pulse of the voltage may have any waveform, such as a rectangular pulse or a triangular pulse. The bias power supply54may periodically apply the pulse of the voltage to the first electrode221. The time length of a cycle in which the pulse of the voltage is applied from the bias power supply54to the first electrode221is the reciprocal of a bias frequency. The bias frequency is, for example, a frequency in a range of 100 kHz or more and 13.56 MHz or less.

The second region22bincludes a chuck electrode225. The chuck electrode225is a film formed of a conductive material and is provided in the dielectric portion22min the second region22b. The chuck electrode225may have a substantially annular shape in a plan view or may extend around the axis AX. A DC power supply53is electrically connected to the chuck electrode225via a filter53f. The filter53fis a low-pass filter. When a DC voltage from the DC power supply53is applied to the chuck electrode225, an electrostatic attraction force is generated between the second region22band the edge ring ER placed on the second region22b. The edge ring ER is attracted to the second region22bby the generated electrostatic attraction force and is held by the electrostatic chuck22on the second region22b. In addition, the second region22bmay include a pair of electrodes configuring a bipolar electrostatic chuck as chuck electrodes.

The second region22bfurther includes a second electrode222. The second electrode222is a film formed of a conductive material. The second electrode222may have a substantially annular shape in a plan view or may extend around the axis AX. The second electrode222is provided in the dielectric portion22min the second region22b. In addition, the chuck electrode225may extend between the second electrode222and an upper surface of the second region22b.

The plasma processing apparatus1further includes a second feed line82. The second feed line82connects a bias power supply55and the second electrode222to each other. Details of the second feed line82will be described below. Alternatively, the second feed line82may connect the bias power supply54and the second electrode222to each other. In this case, the plasma processing apparatus1may not include the bias power supply55.

The bias power supply55generates a pulse of a voltage applied to the second electrode222as bias energy to draw ions into the substrate W from the plasma generated in the chamber10. The pulse of the voltage may be a negative pulse of the voltage or a positive pulse of the voltage. The pulse of the voltage can have any waveform, such as a rectangular pulse or a triangular pulse. The bias power supply55may periodically apply the pulse of the voltage to the second electrode222. The time length of a cycle in which the pulse of the voltage is applied from the bias power supply55to the second electrode222is the reciprocal of a bias frequency. The bias frequency is, for example, a frequency in a range of 100 kHz or more and 13.56 MHz or less.

In an embodiment, a through-hole is formed substantially in the center of the base20. An insulator83is fitted into the through-hole. The insulator83is formed of an insulating material. The insulator83may have a substantially cylindrical shape. The electrostatic chuck22further includes a terminal22e. The terminal22eis connected to the first electrode221and is exposed to an inner hole of the insulator83at a lower surface of the electrostatic chuck22.

The first feed line81includes a socket81sand a feed pin81p. The feed pin81pand the socket81sare formed of a conductor, such as a metal. The socket81sis provided in the inner hole of the insulator83. The socket81shas an upper portion including an upper end thereof and a lower portion. The upper portion of the socket81smay have a substantially columnar shape. The lower portion of the socket81smay have a substantially cylindrical shape. The upper end of the socket81sis connected to the terminal22e. The upper end of the socket81sis brazed to, for example, the terminal22e.

FIG.4is a view illustrating a feed pin and a socket that can be adopted in the plasma processing apparatus according to an exemplary embodiment. The feed pin81pmay have the same structure as a feed pin100illustrated inFIG.4, and the socket81smay have the same structure as a socket102illustrated inFIG.4.

The feed pin100has a flexible portion100fas a portion between one end and the other end of the feed pin100. The flexible portion100fhas a diameter larger than the diameter of other portions of the feed pin100in the longitudinal direction. Additionally, the flexible portion100fhas flexibility in the radial direction. That is, the flexible portion100fis configured to be elastically deformable in the radial direction. In an embodiment, the flexible portion100fis hollow and provides a plurality of notches100sarranged in the circumferential direction. In the socket102, the flexible portion100fcomes into contact with an inner surface of the socket102in a state where the diameter of the flexible portion100fis reduced, and is held by the socket102.

In the plasma processing apparatus1, since the feed pin81pand the socket81shave the same structure as the feed pin100and the socket102, the feed pin81pis held by the socket81sand reliably comes into contact with the socket81s. Accordingly, the bias energy from the bias power supply54, that is, the pulse of the voltage is stably supplied to the first electrode221.

In an embodiment, the first feed line81may further include a wiring line81w. The wiring line81wconnects the feed pin81pto the bias power supply54. In an embodiment, the first feed line81extends upward through an inner hole of the feed pipe57. Specifically, parts of the wiring line81wand the feed pin81pof the first feed line81extend in the inner hole of the feed pipe57. In an embodiment, an annular member82ris provided in the feed pipe57. The first feed line81may extend upward through an inner hole of the annular member82r. Specifically, the wiring line81wmay extend upward through the inner hole of the annular member82r.

In an embodiment, a plurality of through-holes are formed in the base20. The plurality of through-holes are arranged in the circumferential direction around the axis AX. A plurality of insulators84are fitted in the plurality of through-holes. Each of the plurality of insulators84is formed of an insulating material. Each of the plurality of insulators84may have a substantially cylindrical shape. The electrostatic chuck22further includes a plurality of terminals22f. Each of the plurality of terminals22fis connected to the second electrode222and is exposed to an inner hole of the corresponding insulator among the plurality of insulators84at the lower surface of the electrostatic chuck22.

The second feed line82includes one or more sockets82sand one or more feed pins82p. The one or more sockets82sand the one or more feed pins82pare formed of a conductor, such as a metal. In an embodiment, the second feed line82includes the plurality of sockets82sand the plurality of feed pins82p. Each feed pin82pis fitted in the corresponding socket82s.

The plurality of sockets82sextend in the inner holes of the corresponding insulators among the plurality of insulators84. The plurality of sockets82sare held by the corresponding insulators among the plurality of insulators84via a sleeve86. The plurality of sockets82smay have a substantially cylindrical shape closed at upper ends thereof. The upper ends of the plurality of sockets82sare connected to the plurality of terminals22f, respectively. In an embodiment, the second feed line82includes a plurality of wiring lines82t. The plurality of wiring lines82tis composed of, for example, stranded wires. The plurality of wiring lines82tconnect the plurality of sockets82sto the plurality of terminals22frespectively.

In the plasma processing apparatus1, each feed pin82pand each socket82shave the same structure as the feed pin100and the socket102. Accordingly, each feed pin82pis held by the corresponding socket82sand reliably comes into contact with the corresponding socket82s. Therefore, the bias energy from the bias power supply55, that is, the pulse of the voltage is stably supplied to the edge ring ER via the second electrode222.

Hereinafter,FIG.5will be referred to in addition toFIGS.1to4.FIG.5is a plan view illustrating the second feed line of the plasma processing apparatus according to an exemplary embodiment. In an embodiment, the second feed line82may include a common line82c, the annular member82r, and a plurality of branch lines82b.

The annular member82rhas an annular shape and is formed of a conductor, such as a metal. A central axis of the annular member82rsubstantially coincides with the axis AX. The annular member82ris provided in the inner hole of the feed pipe57. The annular member82ris held by a holder88and may be supported by the feed pipe57via the holder88. The holder88is formed of an insulating material and is interposed between the feed pipe57and the annular member82r.

The common line82cis a wiring line formed of a conductor and connects the bias power supply55(or the bias power supply54) to the annular member82r. The common line82cextends upward through the inner hole of the feed pipe57and is connected to the annular member82rin the feed pipe57.

The plurality of branch lines82bconnect the second electrode222to the annular member82r. Each of the plurality of branch lines82bincludes one of the plurality of feed pins82pand one of the plurality of sockets82s. The plurality of branch lines82bmay have the same length as each other. The plurality of branch lines82bmay be arranged at equal intervals in the circumferential direction with respect to the axis AX.

In an embodiment, each of the plurality of branch lines82bmay further include a wiring line82wand a joint82j. The wiring line82wextends in the radial direction with respect to the axis AX from one end thereof connected to the annular member82rand is connected to the joint82jat the other end thereof. The wiring line82wextends in the radial direction through a hole of the holder88and a hole of the feed pipe57. The wiring line82wmay be bent between the annular member82rand the joint82j. For example, the wiring line82wmay extend in a curved shape between the annular member82rand the joint82j.

The joint82jof each of the plurality of branch lines82bis held between the member24and the member25. The member24and the member25are provided between the support18and the base20. One of the plurality of feed pins82pis connected to each joint82jof the plurality of branch lines82b. Each of the plurality of feed pins82pextends upward from the joint82jand is fitted into the corresponding socket82s.

According to the second feed line82including the common line82c, the annular member82r, and the plurality of branch lines82b, the bias energy can be equally supplied to the edge ring ER in the circumferential direction.

While various exemplary embodiments have been described above, various additions, omissions, substitutions and changes may be made without being limited to the exemplary embodiments described above. Elements of the different embodiments may be combined to form another embodiment.

For example, the second feed line82may include a single feed pin and a single socket.

Additionally, in another embodiment, a plasma processing apparatus may be a capacitively-coupled plasma processing apparatus different from the plasma processing apparatus1. In yet another embodiment, a plasma processing apparatus may be an inductively coupled plasma processing apparatus, an electron cyclotron resonance (ECR) plasma processing apparatus, or a plasma processing apparatus that generates plasma using a surface wave such as microwaves.

Hereinafter, the first to fourth experiments performed for the evaluation of the plasma processing apparatus1will be described. In the first to fourth experiments, plasma etching of a silicon oxide film of a sample substrate was performed using the plasma processing apparatus1. The plasma processing apparatus1used in the first to fourth experiments had six feed pins82p, six sockets82s, and six branch lines82b. The number of branch lines82bused in the first to fourth experiments, that is, the number of power supply lines was different from each other. In the first experiment, the six feed pins82pwere fitted into the six sockets82s, respectively. That is, in the first experiment, the bias power supply55was connected to the second electrode222by using all of the plurality of branch lines82b. In the second experiment, one feed pin82pwas removed from one socket82sand the bias power supply55was connected to the second electrode222by using five branch lines82b. In the third experiment, the three feed pins82pwere removed from the three sockets82sand the bias power supply55was connected to the second electrode222by using the three branch lines82b. In the fourth experiment, the five feed pins82pwere removed from the five sockets82sand the bias power supply55was connected to the second electrode222by using one branch line82b. Hereinafter, the conditions for the plasma etching in the first to fourth experiments are shown. In addition, in the first to fourth experiments, the radio-frequency power of the radio-frequency power supply51, the pulse of the voltage of the bias power supply54, and the pulse of the voltage of the bias power supply55were on-off modulated by a repetition frequency of 10 kHz and an ON duty ratio of 60% and synchronized with each other.

<Number of Power Supply Lines in First to Fourth Experiments>

First experiment (No. 1): 6Second experiment (No. 2): 5Third experiment (No. 3): 3Fourth experiment (No. 4): 1
<Plasma Etching Conditions in First to Fourth Experiments>Processing gas: Mixed gas of CF4gas, O2gas, and Ar gasPressure in chamber10: 10 mTorr (1.333 Pa)Radio-frequency power of radio-frequency power supply51: 2500 W and 40 MHzPulse of voltage of bias power supply54: −3600 V, 400 kHz bias frequency, and 20% ON duty ratioPulse of voltage of bias power supply55: −360 V, 400 kHz bias frequency, and 20% ON duty ratio

In the first to fourth experiments, the etching rates of silicon oxide films at a plurality of positions in the radial direction of the sample substrate were obtained. Then, a difference ΔER between the etching rate of a silicon oxide film at each of the plurality of positions obtained in each of the second to fourth experiments and the etching rate of a silicon oxide film at the corresponding position obtained in the first experiment was determined.FIG.6shows the results of the experiments. InFIG.6, the horizontal axis represents a plurality of positions in the radial direction of the sample substrate as distances from the center of the sample substrate. InFIG.6, the vertical axis represents ΔER. Additionally, inFIG.6, No. 2. No. 3, and No. 4 indicate the ΔER of the second to fourth experiments, respectively. As illustrated inFIG.6, in the fourth experiment, that is a case where the bias power supply55is connected to the second electrode222by using only one branch line among the six branch lines82b, ΔER has a negative value having a large absolute value. Accordingly, the etching rate was significantly decreased. On the other hand, in a case where the bias power supply55was connected to the second electrode222by using more branch lines82b, the absolute value of ΔER becomes smaller. Accordingly, it was confirmed that it is preferable to use a plurality of branch lines82b.

From the foregoing description, it will be appreciated 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 following claims.