Plasma processing device and plasma processing method

Abstract

Provided is a technique for improving the waveform of a DC signal. A plasma processing device is provided. The plasma processing device is provided with a chamber, a substrate support unit, an RF generation unit, a DC generation unit, a first switch, and a control unit. The substrate support unit is disposed in the chamber and includes a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed in the electrostatic chuck. The RF generator is coupled to the conductive base via a first signal line and is configured to generate an RF signal. The DC generator is coupled to the bias electrode via a second signal line and is configured to generate a pulsed DC signal. The first switch is disposed on the first signal line. The control unit is configured to control the first switch to disconnect the electrical connection between the conductive base and the RF generation unit while the pulsed DC signal is supplied from the DC generation unit to the bias electrode.

Description

Plasma processing apparatus and plasma processing method

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

[0002] Patent Document 1 discloses controlling the connection between the mounting table and a high frequency power supply, and the connection between the mounting table and a square waveform DC voltage application unit.

[0003] JP 2016-105490 A

[0004] The present disclosure provides techniques for improving the waveform of a DC signal.

[0005] In one exemplary embodiment of the present disclosure, there is provided a plasma processing apparatus including: a chamber; a substrate support disposed in the chamber, the substrate support including a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed in the electrostatic chuck; an RF generator coupled to the conductive base via a first signal line and configured to generate an RF signal; a DC generator coupled to the bias electrode via a second signal line and configured to generate a pulsed DC signal; a first switch disposed on the first signal line; and a controller configured to control the first switch to disconnect an electrical connection between the conductive base and the RF generator while the pulsed DC signal is supplied from the DC generator to the bias electrode.

[0006] According to one exemplary embodiment of the present disclosure, a technique for improving the waveform of a DC signal can be provided.

[0007] FIG. 1 is a diagram for explaining an example of the configuration of a plasma processing system. FIG. 2 is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 3 is a diagram showing an example of the configuration of a substrate support and a power supply. FIG. 4 is a diagram showing another example of the configuration of a substrate support and a power supply. FIG. 5 is a diagram showing another example of the configuration of a substrate support and a power supply. FIG. 6 is a diagram showing another example of the configuration of a substrate support and a power supply. FIG. 7 is a diagram showing another example of the configuration of a substrate support and a power supply. FIG. 8 is a diagram showing an example of the supply of each signal in cycle CY. FIG. 9 is a diagram showing the waveform of a pulsed DC signal of Example 1. FIG. 10 is a diagram showing the waveform of a pulsed DC signal of Reference Example 1. FIG. 11 is a diagram showing the waveforms of pulsed DC signals of Example 2 and Reference Example 2.

[0008] Hereinafter, each embodiment of the present disclosure will be described.

[0009] In one exemplary embodiment, a plasma processing apparatus is provided, comprising: a chamber; a substrate support disposed within the chamber, the substrate support including a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed within the electrostatic chuck; an RF generator coupled to the conductive base via a first signal line and configured to generate an RF signal; a DC generator coupled to the bias electrode via a second signal line and configured to generate a pulsed DC signal; a first switch disposed on the first signal line; and a controller configured to control the first switch to disconnect an electrical connection between the conductive base and the RF generator while the pulsed DC signal is supplied from the DC generator to the bias electrode.

[0010] In one exemplary embodiment, the device further includes a second switch disposed on the second signal line, and the control unit is configured to control the second switch to disconnect the electrical connection between the DC generating unit and the bias electrode while the RF signal is supplied from the RF generating unit to the conductive base.

[0011] In one exemplary embodiment, the RF generator is a bias RF generator that generates a bias RF signal.

[0012] In one exemplary embodiment, the plasma processing apparatus further comprises an upper electrode disposed above the substrate support, and a source RF generator coupled to the upper electrode and configured to generate a source RF signal.

[0013] In one exemplary embodiment, the source RF signal has a first power level during a first period in each cycle, a second power level during a second period after the first period in each cycle, a third power level during a third period after the second period in each cycle, and a fourth power level during a fourth period after the third period in each cycle, the second power level being less than the first power level and the fourth power level being a zero power level; and the bias RF signal has a fifth power level during the first period in each cycle. a sixth power level in a second period within each cycle, a seventh power level in a third period within each cycle, and an eighth power level in a fourth period within each cycle, the fifth and eighth power levels being zero power levels; and the pulsed DC signal has a sequence of voltage pulses having a first voltage level in the first, second, and third periods within each cycle and a second voltage level in the fourth period within each cycle, the first voltage level being zero voltage level.

[0014] In one exemplary embodiment, the RF generator is a source RF generator that generates a source RF signal.

[0015] In one exemplary embodiment, the device further includes a bias RF generating unit coupled to the conductive base via a third signal line and configured to generate a bias RF signal, and a third switch disposed on the third signal line.

[0016] In one exemplary embodiment, the control unit is configured to control the third switch to disconnect the electrical connection between the conductive base and the bias RF generator while the pulsed DC signal is supplied from the DC generator to the bias electrode.

[0017] In one exemplary embodiment, the control unit is configured to control the first switch to disconnect the electrical connection between the DC generator and the bias electrode while the bias RF signal is supplied from the bias RF generator to the conductive base.

[0018] In one exemplary embodiment, the source RF signal has a first power level during a first period in each cycle, a second power level during a second period after the first period in each cycle, a third power level during a third period after the second period in each cycle, and a fourth power level during a fourth period after the third period in each cycle, the second power level being less than the first power level and the fourth power level being a zero power level; and the bias RF signal has a fifth power level during the first period in each cycle. a sixth power level in a second period within each cycle, a seventh power level in a third period within each cycle, and an eighth power level in a fourth period within each cycle, the fifth and eighth power levels being zero power levels; and the pulsed DC signal has a sequence of voltage pulses having a first voltage level in the first, second, and third periods within each cycle and a second voltage level in the fourth period within each cycle, the first voltage level being zero voltage level.

[0019] In one exemplary embodiment, a plasma processing method is provided that is performed in a plasma processing apparatus, the plasma processing apparatus including: a chamber; a substrate support disposed in the chamber, the substrate support including a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed in the electrostatic chuck; an RF generator coupled to the conductive base via a first signal line and configured to generate an RF signal; a DC generator coupled to the bias electrode via a second signal line and configured to generate a pulsed DC signal; and a first switch disposed on the first signal line, the plasma processing method including: (a) supplying an RF signal from the RF generator to the conductive base via the first signal line; and (b) supplying the pulsed DC signal from the DC generator to the bias electrode via the second signal line, wherein during (b), the first switch disconnects the electrical connection between the conductive base and the RF generator.

[0020] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are designated by the same reference numerals, and redundant explanations will be omitted. Unless otherwise specified, the positional relationships, such as up, down, left, and right, will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

[0021] <Configuration Example of Plasma Processing System> FIG. 1 is a diagram illustrating a configuration example of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0022] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma generated in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like. Various types of plasma generators may be used, including alternating current (AC) plasma generators and direct current (DC) plasma generators. In one embodiment, the AC signal (AC power) used in the AC plasma generator has a frequency in the range of 100 kHz to 10 GHz. Thus, AC signals include radio frequency (RF) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0023] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0024] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0025] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0026] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0027] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32, which will be described later, may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal, which will be described later, is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0028] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0029] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the backside of the substrate W and the central region 111a.

[0030] The showerhead 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The process gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0031] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

[0032] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This generates a plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generation unit 12. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0033] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0034] The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0035] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0036] In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0037] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0038] 3A is a diagram showing an example of the configuration of the substrate support unit and the power supply. In one embodiment, the substrate support unit 11 includes a conductive base 1110 and an electrostatic chuck 1111 disposed on the base 1110. The conductive base 1110 may be made of, for example, aluminum. A chuck electrode 1111b and a bias electrode 1111c are disposed inside the electrostatic chuck 1111. The bias electrode 1111c may be disposed below the chuck electrode 1111b. The bias electrode 1111c is grounded, and a first parasitic capacitor C1 may be generated between the bias electrode 1111c and the ground potential.

[0039] In one embodiment, a first RF generator 31a that generates a source RF signal is coupled to the showerhead 13. A second RF generator 31b that generates a bias RF signal is coupled to the base 1110 via a first signal line L1. The base 1110 is grounded, and a second parasitic capacitor C2 may be generated between the base 1110 and the ground potential.

[0040] In one embodiment, the first signal line L1 is provided with an impedance matching circuit 50 and a first switch S1, in this order, from the second RF generating unit 31b toward the base 1110. The first switch S1 may be provided outside the chamber 10. The first switch S1 is configured to be controlled by the control unit 2 to turn on (connect power to) or disconnect the electrical connection between the second RF generating unit 31b and the base 1110. In one embodiment, an RF filter may be provided on the first signal line L1 between the second RF generating unit 31b and the first switch S1. The RF filter is configured to suppress the source RF signal from entering the second RF generating unit 31b via the first signal line L1. The RF filter may be provided outside the chamber 10.

[0041] In one embodiment, the first DC generator 32a is coupled to the bias electrode 1111c via a second signal line L2. In one embodiment, the first DC generator generates a pulsed DC signal. The second signal line L2 from the first DC generator 32a to the bias electrode 1111c is grounded, and a third parasitic capacitor C3 may be generated between a node n on the second signal line L2 and the ground potential.

[0042] In one embodiment, a second switch S2 is disposed on the second signal line L2. The second switch S2 may be disposed outside the chamber 10. The second switch S2 is controlled by the control unit 2 to turn on (connect current to) or disconnect the electrical connection between the first DC generating unit 32a and the bias electrode 1111c.

[0043] In one embodiment, an RF filter 60 may be disposed on the second signal line L2. The RF filter 60 may be disposed, for example, between the node n and the second switch S2. The RF filter 60 is configured to suppress the source RF signal and / or the bias RF signal (hereinafter also referred to as "RF signal") from entering the first DC generating unit 32a via the second signal line L2. The RF filter 60 may remove signals of a specific frequency depending on the frequency of the RF signal. The RF filter 60 may be a coil. The RF filter 60 may be disposed outside the chamber 10. In one embodiment, the RF filter 60 may not be provided.

[0044] In one embodiment, in addition to the RF filter 60, a ringing suppression circuit 62 may be disposed on the second signal line L2. The ringing suppression circuit 62 may be disposed, for example, between the first DC generator 32a and the node n. For example, when the second switch S2 is turned on (conducting) and the first switch S1 is turned off, resonance occurs between the inductor of the RF filter 60 and the capacitors on the signal line (the first to third parasitic capacitors C1 to C3), which may cause ringing (high-frequency components) in the pulsed DC signal. Furthermore, when the first switch S1 and the second switch S2 are simultaneously connected, resonance occurs between the inductor of the RF filter 60 and the capacitors on the signal line (the first to third parasitic capacitors C1 to C3, the impedance matching circuit 50), which may cause ringing (high-frequency components) in the pulsed DC signal. The ringing suppression circuit 62 is configured to suppress ringing superimposed on such pulsed DC signal. The ringing suppression circuit 62 may be configured to include a parallel resonant circuit 620. The ringing suppression circuit 62 may be configured to include a ferrite core 622. The ringing suppression circuit 62 may be disposed outside the chamber 10.

[0045] FIG. 3B is a diagram showing another example of the configuration of the substrate support and power supply. In this example, the first RF generating unit 31a, which generates a source RF signal, is coupled to the base 1110 via a third signal line L3. In one embodiment, the third signal line L3 is provided with an impedance matching circuit 52 and a third switch S3, in this order, from the first RF generating unit 31a toward the base 1110. The third switch S3 may be disposed outside the chamber 10. The third switch S3 is configured to be controlled by the controller 2 to turn on (connect current to) or disconnect the electrical connection between the first RF generating unit 31a and the base 1110. The other configuration may be similar to the configuration shown in FIG. 3A. Note that in FIG. 3B, the first signal line L1 and the third signal line L3 are each coupled to the base 1110, but this is not limited to this. For example, a first signal line L1 extending from the first switch S1 to the base 1110 and a third signal line L3 extending from the third switch S3 to the base 1110 may be joined into one signal line before being coupled to the base 1110. Then, the one signal line may be coupled to the base 1110.

[0046] FIG. 3C shows another example of the configuration of the substrate support and power supply. In this example, the first DC generating unit 32a is coupled to the base 1110 via the second signal line L2. The other configuration may be the same as the configuration shown in FIG. 3A. In the configuration shown in FIG. 3B, the first DC generating unit 32a may be coupled to the base 1110 via the second signal line L2, as in FIG. 3C. In FIG. 3C, the first signal line L1 and the second signal line L2 are each coupled to the base 1110, but this is not limiting. For example, the first signal line L1 extending from the first switch S1 to the base 1110 and the second signal line L2 extending from the second switch S2 to the base 1110 may be joined into a single signal line before being coupled to the base 1110. This single signal line may then be coupled to the base 1110.

[0047] FIG. 3D shows another example of the configuration of the substrate support and power supply. In this example, the second RF generator 31b is coupled to the bias electrode 1111c via the first signal line L1. The other configurations may be similar to those shown in FIG. 3A. In the configuration shown in FIG. 3B, the first DC generator 32a may be coupled to the bias electrode 1111c via the second signal line L2, as in FIG. 3D. In FIG. 3D, the first signal line L1 and the second signal line L2 are each coupled to the bias electrode 1111c, but this is not limited thereto. For example, the first signal line L1 extending from the first switch S1 to the bias electrode 1111c and the second signal line L2 extending from the second switch S2 to the bias electrode 1111c may be merged into a single signal line before being coupled to the bias electrode 1111c. This single signal line may then be coupled to the bias electrode 1111c.

[0048] 3A-3D, the electrostatic chuck 1111 may include another bias electrode in addition to or in place of the bias electrode 1111c. The other bias electrode may be disposed within the electrostatic chuck 1111 between the ring assembly 112 and the base 1110. The first DC generator 32a may be coupled to the other bias electrode.

[0049] FIG. 3E shows another example of the configuration of the substrate support and power supply. In this example, the electrostatic chuck 1111 includes a bias electrode 1111d in addition to the bias electrode 1111c. The bias electrode 1111d has an annular shape and is disposed outside the bias electrode 1111c between the ring assembly 112 and the base 1110. The first DC generator 32a is coupled to both the bias electrode 1111c and the bias electrode 1111d. In the example shown in FIG. 3E, the first DC generator 32a is connected to the lower surface of the conductive base 1110 via a second signal line L2 and is coupled to the bias electrode 1111c and the bias electrode 1111d from the upper surface of the base 1110 via signal lines La and Lb, respectively. In one embodiment, the second RF generator 31b may be coupled to the same electrode as the first DC generator 32a. For example, as shown in FIG. 3E , the second RF generating unit 31b may be coupled to both the bias electrode 1111c and another bias electrode 1111d. That is, the second RF generating unit 31b may be connected to the lower surface of the conductive base 1110 via a first signal line L1, and may be coupled to the bias electrode 1111c and another bias electrode 111d from the upper surface of the base 1110 via signal lines La and Lb, respectively. Note that in FIG. 3E , the first signal line L1 and the second signal line L2 are each coupled to the lower surface of the base 1110, but this is not limited thereto. For example, the first signal line L1 extending from the first switch S1 to the base 1110 and the second signal line L2 extending from the second switch S2 to the base 1110 may be merged into a single signal line before being coupled to the base 1110. Then, the single signal line may be coupled to the base 1110.

[0050] 3F illustrates another example of a substrate support and power supply configuration. In one embodiment, the first signal line L1 and the second signal line L2 may be connected outside the chamber 10 and coupled to the lower electrode. For example, as shown in FIG. 3F, the first signal line L1 and the second signal line L2 may be connected outside the chamber 10 and coupled to the bias electrode 1111d.

[0051] In one embodiment, some or all of the components of the first signal line L1 and the second signal line L2 may be configured as a single unit outside the chamber 10. For example, as shown in FIG. 3F , the unit PU outside the chamber 10 includes a first switch S1, an impedance matching circuit 50, and an RF filter 52 for the first signal line L1. The unit PU further includes a second switch S2 and a parallel resonant circuit 64 for the second signal line L2. The unit PU may include the above components within a single housing. The RF filter 52 is configured to suppress the source RF signal from entering the second RF generating unit 31b via the first signal line L1. In one embodiment, as shown in FIG. 3F , a DC control unit 66 may be disposed outside the unit PU and between the first DC generating unit 32a and the parallel resonant circuit 64 for the second signal line L2. The DC control unit 66 may include a ringing suppression circuit 62 (see FIG. 3A ) disposed therein.

[0052] 3A to 3F, the first switch S1 to the third switch S3 (hereinafter also referred to as "each switch") may be, for example, an electronic switch. The electronic switch may be configured to include an element that switches an electrical signal, such as a field effect transistor (FET). The electronic switch including a FET may be configured similarly to the switching unit described in U.S. Pat. No. 10,553,407 (e.g., switching unit 72 shown in FIG. 3 of the specification), for example.

[0053] <Example of Plasma Processing Method> The plasma processing performed using the plasma processing apparatus 1 includes an etching process that uses plasma to etch a film on the substrate W. In one embodiment, the plasma processing is executed by the control unit 2.

[0054] First, the substrate W is carried into the chamber 10 by the transport arm, placed on the substrate support 11 by the lifter, and held by suction on the substrate support 11 as shown in FIG.

[0055] Next, the processing gas is supplied to the shower head 13 by the gas supply unit 20, and is then supplied to the plasma processing space 10s from the shower head 13. The processing gas supplied at this time includes a gas that generates activated species necessary for etching the substrate W.

[0056] In one embodiment, a source RF signal for plasma generation is supplied to the lower electrode and / or the upper electrode. A bias signal for ion attraction may be supplied to the lower electrode. At this time, the atmosphere in the plasma processing space 10s may be exhausted through the gas exhaust port 10e, and the pressure in the plasma processing space 10s may be reduced to a predetermined pressure. As a result, plasma is generated in the plasma processing space 10s, and the substrate W is etched.

[0057] (Example of plasma processing in the configuration shown in FIG. 3A) When the plasma processing apparatus 1 has the configuration shown in FIG. 3A, a source RF signal generated by the first RF generating unit 31a is supplied to the shower head 13. A bias RF signal generated by the second RF generating unit 31b is supplied to the base 1110 via a first signal line L1. A pulsed DC signal generated by the first DC generating unit 32a is supplied to the bias electrode 1111c via a second signal line L2.

[0058] In one embodiment, the control unit 2 may control the first switch S1 to disconnect the electrical connection between the base 1110 and the second RF generating unit 31b while the pulsed DC signal is supplied from the first DC generating unit 32a to the bias electrode 1111c. When the base 1110 and the second RF generating unit 31b are electrically connected, resonance may occur between the first DC generating unit 32a and the second RF generating unit 31b and / or the impedance matching circuit 50, causing ringing (high-frequency components) in the pulsed DC signal. By disconnecting the electrical connection between the base 1110 and the second RF generating unit 31b, the ringing superimposed on the pulsed DC signal can be suppressed.

[0059] In one embodiment, the control unit 2 may control the second switch S2 to disconnect the electrical connection between the bias electrode 1111c and the first DC generation unit 32a while a source RF signal is supplied from the first RF generation unit 31a to the shower head 13. The control unit 2 may also control the second switch S2 to disconnect the electrical connection between the bias electrode 1111c and the first DC generation unit 32a while a bias RF signal is supplied from the second RF generation unit 31b to the base 1110. This prevents the source RF signal and / or the bias RF signal from entering the first DC generation unit 32a via the second signal line L2. This makes it possible to eliminate the RF filter on the second signal line L2, or to reduce the coil constant of the RF filter.

[0060] (Example of plasma processing in the configuration shown in FIG. 3B) When the plasma processing apparatus 1 has the configuration shown in FIG. 3B, a source RF signal generated by the first RF generating unit 31a is supplied to the base 1110 via a third signal line L3. A bias RF signal generated by the second RF generating unit 31b is supplied to the base 1110 via a first signal line L1. A pulsed DC signal generated by the first DC generating unit 32a is supplied to the bias electrode 1111c via a second signal line L2.

[0061] In one embodiment, the control unit 2 may control the third switch S3 to disconnect the electrical connection between the base 1110 and the first RF generating unit 31a while the pulsed DC signal is supplied from the first DC generating unit 32a to the bias electrode 1111c. The control unit 2 may also control the first switch S1 to disconnect the electrical connection between the base 1110 and the second RF generating unit 31b while the pulsed DC signal is supplied from the first DC generating unit 32a to the bias electrode 1111c. When the base 1110 is electrically connected to the first RF generating unit 31a and the second RF generating unit 31b, resonance may occur between the first DC generating unit 32a, the first RF generating unit 31a and / or the impedance matching circuit 52, and the second RF generating unit 31b and / or the impedance matching circuit 50, causing ringing (high-frequency components) in the pulsed DC signal. By disconnecting the electrical connection between the base 1110 and the first RF generating unit 31a and the second RF generating unit 31b, it is possible to suppress ringing superimposed on the pulsed DC signal.

[0062] In one embodiment, the control unit 2 may control the second switch S2 to disconnect the electrical connection between the bias electrode 1111c and the first DC generation unit 32a while a source RF signal is supplied from the first RF generation unit 31a to the shower head 13. The control unit 2 may also control the second switch S2 to disconnect the electrical connection between the bias electrode 1111c and the first DC generation unit 32a while a bias RF signal is supplied from the second RF generation unit 31b to the base 1110. This prevents the source RF signal and / or the bias RF signal from entering the first DC generation unit 32a via the second signal line L2. This makes it possible to eliminate the RF filter on the second signal line L2, or to reduce the coil constant of the RF filter.

[0063] (Example of Supply of Each Signal) Fig. 4 is a diagram showing an example of supply of each signal in a cycle CY. In Fig. 4, "RF1", "RF2", and "DC" respectively indicate a source RF signal, a bias RF signal, and a pulsed DC signal. As shown in Fig. 4, a cycle CY has a first period T1, a second period T2, a third period T3, and a fourth period T4, in this order. The cycle CY is executed multiple times at a predetermined repetition frequency (e.g., 0.1 kHz to 50 kHz) during plasma processing of a substrate W.

[0064] In one embodiment, the source RF signal (RF1) has a first power level P1 during a first period T1 within each cycle CY, a second power level P2 during a second period T2 within each cycle, a third power level P3 during a third period T3 within each cycle, and a fourth power level P4 during a fourth period T4 within each cycle. In one embodiment, the first power level P1 has a higher power level (Hi) than the second to fourth power levels. In one embodiment, the second power level P2 and the third power level have a lower power level (Lo) than the first power level P1. Note that the third power level P3 may be the same as the second power level P2 or may be greater or less than the second power level P2. The fourth power level P4 has a zero power level.

[0065] In one embodiment, the bias RF signal (RF2) has a fifth power level P5 during a first period T1 in each cycle CY, a sixth power level P6 during a second period T2 in each cycle, a seventh power level P7 during a third period T3 in each cycle, and an eighth power level P8 during a fourth period T4 in each cycle. In one embodiment, the fifth power level P5, the seventh power level P7, and the eighth power level P8 have zero power levels. The sixth power level P6 has a power level greater than zero. Note that the seventh power level P7 may have a power level greater than zero. The seventh power level P7 may have the same power level as the sixth power level P6, or may have a power level greater than or less than the sixth power level P6.

[0066] In one embodiment, the pulsed DC signal (DC) has a sequence of voltage pulses having a first voltage level V1 in a first period T1, a second period T2, and a third period T3 within each cycle CY and a second voltage level V2 in a fourth period within each cycle CY. In one embodiment, the first voltage level V1 has a zero voltage level. In one embodiment, the second voltage level V2 has negative polarity. In one embodiment, the sequence of voltage pulses having the second voltage level V2 has a predetermined pulse frequency. For example, the pulse frequency may be 100 kHz to 1 MHz, or 300 kHz to 600 Hz. In one example, the pulse frequency is 400 kHz. The duty ratio (proportion of pulse-on time in one period) of the sequence of voltage pulses may be 10% to 50%.

[0067] In one embodiment, during the first period T1 to the third period T3 in which the source RF signal and / or the bias RF signal is supplied, the control unit 2 may control the second switch S2 (see FIGS. 3A and 3B) to disconnect the electrical connection between the bias electrode 1111c and the first DC generating unit 32a. This makes it possible to prevent the source RF signal and / or the bias RF signal from entering the first DC generating unit 32a via the second signal line L2.

[0068] In one embodiment, during the fourth period T4 in which the pulsed DC signal is supplied, the control unit 2 may control the first switch S1 (FIG. 3A) to disconnect the electrical connection between the base 1110 and the second RF generating unit 31b. Also, in another embodiment, during the fourth period T4 in which the pulsed DC signal is supplied, the control unit 2 may control the first switch S1 and the third switch S3 (see FIG. 3B) to disconnect the electrical connection between the base 1110 and the first RF generating unit 31a and the second RF generating unit 31b. This suppresses ringing from being superimposed on the pulsed DC signal.

[0069] In the example shown in FIG. 4 , a source RF signal, a bias RF signal, and a pulsed DC signal are supplied during the first period T1 to the third period T4 of a cycle CY, but this is not limiting. For example, during one or more cycles CY, only the source RF signal and / or the bias RF signal may be supplied. During these one or more cycles CY, the controller 2 may control the second switch S2 to disconnect the electrical connection between the lower electrode and the first DC generator 32a. Furthermore, during another one or more cycles CY, only the pulsed DC signal may be supplied. During these one or more cycles CY, the controller 2 may control the first switch S1 to disconnect the electrical connection between the lower electrode and the second RF generator 31b.

[0070] According to the plasma processing method of the embodiment, the waveform of the DC signal can be improved.

[0071] <Examples> The present disclosure is not limited in any way by the following examples.

[0072] 3A was used. While a pulsed DC signal was being supplied from the first DC generator 32a to the bias electrode 1111c, the electrical connection between the base 1110 and the second RF generator 31b was cut off, and the substrate potential on the electrostatic chuck 1111 was measured.

[0073] 3A was used in Reference Example 1. While a pulsed DC signal was being supplied from the first DC generator 32a to the bias electrode 1111c, the electrical connection between the base 1110 and the second RF generator 31b was turned on (energized), and the substrate potential on the electrostatic chuck 1111 was measured.

[0074] 5A is a diagram showing the waveform of a pulsed DC signal in Example 1. FIG. 5B is a diagram showing the waveform of a pulsed DC signal in Reference Example 1. The substrate potential in Example 1 was such that the pulsed DC signal had a waveform closer to a square waveform than in Reference Example 1. That is, it was confirmed that ringing (high-frequency components) superimposed on the pulsed DC signal was reduced.

[0075] 3F was used in Example 2. While a pulsed DC signal was supplied from the first DC generator 32a to the bias electrode 1111c, the electrical connection between the bias electrode 1111c and the second RF generator 31b was cut off, and the substrate potential on the electrostatic chuck 1111 was measured.

[0076] 3F was used in Reference Example 2. While a pulsed DC signal was supplied from the first DC generator 32a to the bias electrode 1111c, the electrical connection between the bias electrode 1111c and the second RF generator 31b was turned on (energized), and the substrate potential on the electrostatic chuck 1111 was measured.

[0077] 6 is a diagram showing the waveform (E2) of the pulsed DC signal in Example 2 and the waveform (R2) of the pulsed DC signal in Reference Example 2. As shown in Fig. 6, the substrate potential in Example 2 had an earlier rise time of the pulsed DC signal than in Reference Example 2. This is thought to be because in Example 2, the lower electrode and the second RF generating unit 31b were electrically disconnected, thereby suppressing the influence of the capacitive components of the RF filter 52 and the like on the first signal line L1.

[0078] Embodiments of the present disclosure further include the following aspects.

[0079] (Supplementary Note 1) A plasma processing apparatus comprising: a chamber; a substrate support disposed in the chamber, the substrate support including a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed in the electrostatic chuck; an RF generator coupled to the conductive base via a first signal line and configured to generate an RF signal; a DC generator coupled to the bias electrode via a second signal line and configured to generate a pulsed DC signal; a first switch disposed on the first signal line; and a controller configured to control the first switch to disconnect an electrical connection between the conductive base and the RF generator while the pulsed DC signal is supplied from the DC generator to the bias electrode.

[0080] (Supplementary Note 2) The plasma processing apparatus according to Supplementary Note 1, further comprising a second switch arranged on the second signal line, wherein the control unit is configured to control the second switch to disconnect the electrical connection between the DC generation unit and the bias electrode while the RF signal is supplied from the RF generation unit to the conductive base.

[0081] (Supplementary Note 3) The plasma processing apparatus according to Supplementary Note 1 or Supplementary Note 2, wherein the RF generating unit is a bias RF generating unit that generates a bias RF signal.

[0082] (Supplementary Note 4) The plasma processing apparatus according to Supplementary Note 3, further comprising: an upper electrode disposed above the substrate support; and a source RF generating unit coupled to the upper electrode and configured to generate a source RF signal.

[0083] (Supplementary Note 5) The source RF signal has a first power level during a first period in each cycle, a second power level during a second period after the first period in each cycle, a third power level during a third period after the second period in each cycle, and a fourth power level during a fourth period after the third period in each cycle, the second power level being lower than the first power level and the fourth power level being zero power level; the bias RF signal has a fifth power level during the first period in each cycle, a sixth power level during the second period in each cycle, a seventh power level during the third period in each cycle, and an eighth power level during the fourth period in each cycle, the fifth power level and the eighth power level being zero power levels; 5. The plasma processing apparatus of claim 4, wherein the pulsed DC signal comprises a sequence of voltage pulses having a first voltage level during the first period, the second period, and the third period in each cycle and a second voltage level during the fourth period in each cycle, the first voltage level being a zero voltage level.

[0084] (Supplementary Note 6) The plasma processing apparatus according to Supplementary Note 1 or Supplementary Note 2, wherein the RF generating unit is a source RF generating unit that generates a source RF signal.

[0085] (Supplementary Note 7) The plasma processing apparatus according to Supplementary Note 6, further comprising: a bias RF generating unit coupled to the conductive base via a third signal line and configured to generate a bias RF signal; and a third switch disposed on the third signal line.

[0086] (Supplementary Note 8) The plasma processing apparatus according to Supplementary Note 7, wherein the control unit is configured to control the third switch to disconnect the electrical connection between the conductive base and the bias RF generation unit while the pulsed DC signal is supplied from the DC generation unit to the bias electrode.

[0087] (Supplementary Note 9) The plasma processing apparatus according to Supplementary Note 7 or Supplementary Note 8, wherein the control unit is configured to control the first switch to disconnect the electrical connection between the DC generation unit and the bias electrode while the bias RF signal is supplied from the bias RF generation unit to the conductive base.

[0088] (Supplementary Note 10) The source RF signal has a first power level during a first period in each cycle, a second power level during a second period after the first period in each cycle, a third power level during a third period after the second period in each cycle, and a fourth power level during a fourth period after the third period in each cycle, the second power level being lower than the first power level and the fourth power level being zero power level; the bias RF signal has a fifth power level during the first period in each cycle, a sixth power level during the second period in each cycle, a seventh power level during the third period in each cycle, and an eighth power level during the fourth period in each cycle, the fifth power level and the eighth power level being zero power levels; 10. The plasma processing apparatus of claim 7, wherein the pulsed DC signal comprises a sequence of voltage pulses having a first voltage level during the first period, the second period, and the third period in each cycle, and a second voltage level during the fourth period in each cycle, and the first voltage level is a zero voltage level.

[0089] (Supplementary Note 11) A plasma processing method performed in a plasma processing apparatus, the plasma processing apparatus comprising: a chamber; a substrate support disposed in the chamber, the substrate support including a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed in the electrostatic chuck; an RF generation unit coupled to the conductive base via a first signal line and configured to generate an RF signal; a DC generation unit coupled to the bias electrode via a second signal line and configured to generate a pulsed DC signal; and a first switch disposed on the first signal line, the plasma processing method comprising: (a) supplying the RF signal from the RF generation unit to the conductive base via the first signal line; and (b) supplying the pulsed DC signal from the DC generation unit to the bias electrode via the second signal line, wherein during (b), the first switch disconnects the electrical connection between the conductive base and the RF generation unit.

[0090] (Supplementary Note 12) A plasma processing apparatus comprising: a chamber; a substrate support disposed in the chamber, the substrate support including a conductive base and an electrostatic chuck disposed on the conductive base; an RF generation unit coupled to the conductive base via a first signal line and configured to generate an RF signal; a DC generation unit coupled to the conductive base via a second signal line and configured to generate a pulsed DC signal; a first switch disposed on the first signal line; and a controller configured to control the first switch to disconnect an electrical connection between the conductive base and the RF generation unit while the pulsed DC signal is supplied from the DC generation unit to the conductive base.

[0091] (Supplementary Note 13) A plasma processing apparatus comprising: a chamber; a substrate support disposed in the chamber, the substrate support including a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed in the electrostatic chuck; an RF generation unit coupled to the bias electrode via a first signal line and configured to generate an RF signal; a DC generation unit coupled to the bias electrode via a second signal line and configured to generate a pulsed DC signal; a first switch disposed on the first signal line; and a controller configured to control the first switch to disconnect an electrical connection between the conductive base and the RF generation unit while the pulsed DC signal is supplied from the DC generation unit to the bias electrode.

[0092] The above embodiments are described for the purpose of explanation and are not intended to limit the scope of the present disclosure. Various modifications can be made to the above embodiments without departing from the scope and spirit of the present disclosure. For example, some components in one embodiment can be added to other embodiments. Also, some components in one embodiment can be replaced with corresponding components in other embodiments.

[0093] REFERENCE SIGNS LIST 1...plasma processing apparatus, 2...controller, 10...plasma processing chamber, 11...substrate support, 1110...base, 1111...electrostatic chuck, 1111c...bias electrode, 13...shower head, 31a...first RF generator, 31b...second RF generator, 32a...first DC generator, L1...first signal line, L2...second signal line, L3...third signal line, S1...first switch, S2...second switch, S3...third switch, W...substrate

Claims

1. A plasma processing apparatus comprising: a chamber; a substrate support disposed within the chamber, the substrate support including a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed within the electrostatic chuck; an RF generator coupled to the conductive base via a first signal line and configured to generate an RF signal; a DC generator coupled to the bias electrode via a second signal line and configured to generate a pulsed DC signal; a first switch disposed on the first signal line; and a controller configured to control the first switch to disconnect an electrical connection between the conductive base and the RF generator while the pulsed DC signal is supplied from the DC generator to the bias electrode.

2. The plasma processing apparatus of claim 1, further comprising a second switch arranged on the second signal line, wherein the control unit is configured to control the second switch to disconnect the electrical connection between the DC generation unit and the bias electrode while the RF signal is supplied from the RF generation unit to the conductive base.

3. The plasma processing apparatus according to claim 1 or 2, wherein the RF generating unit is a bias RF generating unit that generates a bias RF signal.

4. The plasma processing apparatus of claim 3, further comprising: an upper electrode disposed above the substrate support; and a source RF generating section coupled to the upper electrode and configured to generate a source RF signal.

5. the source RF signal has a first power level during a first period in each cycle, a second power level during a second period after the first period in each cycle, a third power level during a third period after the second period in each cycle, and a fourth power level during a fourth period after the third period in each cycle, the second power level being less than the first power level and the fourth power level being a zero power level; the bias RF signal has a fifth power level during the first period in each cycle, a sixth power level during the second period in each cycle, a seventh power level during the third period in each cycle, and an eighth power level during the fourth period in each cycle, the fifth power level and the eighth power level being zero power levels; 5. The plasma processing apparatus of claim 4, wherein the pulsed DC signal comprises a sequence of voltage pulses having a first voltage level during the first period, the second period, and the third period in each cycle and a second voltage level during the fourth period in each cycle, the first voltage level being a zero voltage level.

6. The plasma processing apparatus according to claim 1 or 2, wherein the RF generating section is a source RF generating section that generates a source RF signal.

7. The plasma processing apparatus of claim 6, further comprising: a bias RF generating unit coupled to the conductive base via a third signal line and configured to generate a bias RF signal; and a third switch disposed on the third signal line.

8. The plasma processing apparatus of claim 7, wherein the control unit is configured to control the third switch to disconnect the electrical connection between the conductive base and the bias RF generating unit while the pulsed DC signal is supplied from the DC generating unit to the bias electrode.

9. The plasma processing apparatus of claim 7, wherein the control unit is configured to control the first switch to disconnect the electrical connection between the DC generation unit and the bias electrode while the bias RF signal is supplied from the bias RF generation unit to the conductive base.

10. the source RF signal has a first power level during a first period in each cycle, a second power level during a second period after the first period in each cycle, a third power level during a third period after the second period in each cycle, and a fourth power level during a fourth period after the third period in each cycle, the second power level being less than the first power level and the fourth power level being a zero power level; the bias RF signal has a fifth power level during the first period in each cycle, a sixth power level during the second period in each cycle, a seventh power level during the third period in each cycle, and an eighth power level during the fourth period in each cycle, the fifth power level and the eighth power level being zero power levels; 8. The plasma processing apparatus of claim 7, wherein the pulsed DC signal comprises a sequence of voltage pulses having a first voltage level during the first period, the second period, and the third period in each cycle and a second voltage level during the fourth period in each cycle, the first voltage level being a zero voltage level.

11. A plasma processing method performed in a plasma processing apparatus, the plasma processing apparatus comprising: a chamber; a substrate support disposed in the chamber, the substrate support including a conductive base, an electrostatic chuck disposed on the conductive base, and a bias electrode disposed in the electrostatic chuck; an RF generation unit coupled to the conductive base via a first signal line and configured to generate an RF signal; a DC generation unit coupled to the bias electrode via a second signal line and configured to generate a pulsed DC signal; and a first switch disposed on the first signal line, the plasma processing method comprising: (a) a step of supplying the RF signal from the RF generation unit to the conductive base via the first signal line; and (b) a step of supplying the pulsed DC signal from the DC generation unit to the bias electrode via the second signal line, and during (b), an electrical connection between the conductive base and the RF generation unit is cut off by the first switch.

Images