Plasma processing method and plasma processing apparatus

Abstract

To provide a technique of controlling the electric potential of a plasma.SOLUTION: A plasma processing method contains: a step of arranging a substrate to a substrate support part; a step of supplying a processing gas for processing the substrate into a chamber; a step of generating a plasma of the processing gas in the chamber by supplying high frequency waves to an upper electrode or the substrate support part; a first application step of periodically applying a first bias voltage to the substrate support part in a first period in a period where the high frequency waves are supplied; and a second application step of periodically applying a second bias voltage to the upper electrode in a second period that is an integral multiple of the first period in a period where the high frequency waves are supplied.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Patent Document 1 describes a processing method as a technique for suppressing a decrease in the etching rate of a substrate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-36658 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for controlling the potential of a plasma. [Means for solving the problem]

[0005] In one exemplary embodiment of the present disclosure, there is provided a plasma processing method for plasma processing a substrate in a plasma processing apparatus, the plasma processing apparatus including a chamber, a substrate support provided in the chamber and configured to support the substrate, and an upper electrode provided in the chamber facing the substrate support, the plasma processing method including the steps of: placing a substrate on the substrate support, supplying a process gas for processing the substrate into the chamber, supplying a high frequency wave to the upper electrode or the substrate support to generate plasma of the process gas in the chamber, a first applying step of periodically applying a first pulse voltage to the upper electrode or the substrate support at a first period during the supply of the high frequency wave, and a second applying step of periodically applying a second pulse voltage to the upper electrode or the substrate support at a second period that is an integer fraction of the first period during the supply of the high frequency wave.

[0006] In one exemplary embodiment of the present disclosure, there is provided a plasma processing apparatus comprising: a chamber; a substrate support disposed within the chamber and configured to support a substrate; an upper electrode disposed within the chamber facing the substrate support; and a controller, wherein the controller performs control to place a substrate on the substrate support, supply a process gas for processing the substrate into the chamber, supply a high frequency wave to the upper electrode or the substrate support to generate plasma of the process gas within the chamber, periodically apply a first pulse voltage to the upper electrode or the substrate support at a first period during the supply of the high frequency wave, and periodically apply a second pulse voltage to the upper electrode or the substrate support at a second period that is an integer fraction of the first period during the supply of the high frequency wave. [Effects of the Invention]

[0007] According to an embodiment of the present disclosure, it is possible to provide a plasma processing method and a plasma processing apparatus capable of controlling the potential of plasma. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram schematically illustrating a substrate processing apparatus 1 according to an exemplary embodiment. [Figure 2] 2 is a partially enlarged view of a substrate support part 11 included in the substrate processing apparatus 1. FIG. [Figure 3] 1 is a flowchart illustrating a substrate processing method according to an exemplary embodiment. [Figure 4] 10 is a timing chart showing periods during which a source RF signal, a first DC signal, and a second DC signal are supplied or applied and stopped. [Figure 5] 4 is a timing chart showing an example of timing at which a first pulse voltage and a second pulse voltage are periodically applied. [Figure 6] 4 is a timing chart showing an example of timing at which a first pulse voltage and a second pulse voltage are periodically applied. [Figure 7] 4 is a timing chart showing an example of timing at which a first pulse voltage and a second pulse voltage are periodically applied. [Figure 8] 4 is a timing chart showing an example of timing at which a first pulse voltage and a second pulse voltage are periodically applied. [Figure 9] 4 is a timing chart showing an example of timing at which a first pulse voltage and a second pulse voltage are periodically applied. [Figure 10] 4 is a timing chart showing an example of timing at which a first pulse voltage and a second pulse voltage are periodically applied. [Figure 11] 4 is a timing chart showing an example of timing at which a first pulse voltage and a second pulse voltage are periodically applied. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, each embodiment of the present disclosure will be described.

[0010] In one exemplary embodiment, a plasma processing method for plasma processing a substrate in a plasma processing apparatus is provided. The plasma processing apparatus includes a chamber, a substrate support provided in the chamber and configured to support a substrate, and an upper electrode provided in the chamber facing the substrate support. The plasma processing method includes the steps of: placing the substrate on the substrate support, supplying a processing gas for processing the substrate into the chamber, supplying a high frequency wave to the upper electrode or the substrate support to generate plasma of the processing gas in the chamber, a first applying step of periodically applying a first pulse voltage to the substrate support at a first period during the supply of the high frequency wave, and a second applying step of periodically applying a second pulse voltage to the upper electrode at a second period that is an integer fraction of the first period, in synchronization with the application of the first pulse voltage, during the supply of the high frequency wave.

[0011] In one exemplary embodiment, the second applying step applies a second pulse voltage to the upper electrode or the substrate support in synchronization with the application of the first pulse voltage.

[0012] In one exemplary embodiment, the integer is one.

[0013] In one exemplary embodiment, the integer is 2 or greater.

[0014] In one exemplary embodiment, the first applying step includes a step of starting application of a first pulse voltage at a first time point and a step of stopping application of the first pulse voltage at a second time point that is later than the first time point, and the second applying step includes a step of starting application of a second pulse voltage at the first time point and a step of stopping application of the second pulse voltage at the second time point.

[0015] In one exemplary embodiment, the first applying step includes a step of starting application of a first pulse voltage at a first time point and a step of stopping application of the first pulse voltage at a second time point that is later than the first time point, and the second applying step includes a step of starting application of a second pulse voltage between the first time point and the second time point and a step of stopping application of the second pulse voltage at a time point that is later than the second time point.

[0016] In one exemplary embodiment, the first applying step includes a step of starting application of a first pulse voltage at a first time point and a step of stopping application of the first pulse voltage at a second time point that is later than the first time point, and the second applying step includes a step of starting application of a second pulse voltage at a second time point and a step of stopping application of the second pulse voltage at a time point that is later than the second time point.

[0017] In one exemplary embodiment, the first applying step includes starting application of a first pulse voltage at a first time point and stopping application of the first pulse voltage at a second time point that is later than the first time point, and the second applying step includes starting application of a second pulse voltage at a third time point that is later than the second time point and stopping application of the second pulse voltage at a time point that is later than the third time point.

[0018] In one exemplary embodiment, the time interval between the start and end of application of the second pulse voltage is equal to the time interval between the start and end of application of the first pulse voltage.

[0019] In one exemplary embodiment, the time interval between the start and end of application of the second pulse voltage is longer than the time interval between the start and end of application of the first pulse voltage.

[0020] In one exemplary embodiment, the time interval between the start and end of application of the second pulse voltage is shorter than the time interval between the start and end of application of the first pulse voltage.

[0021] In one exemplary embodiment, generating the plasma includes applying a radio frequency to the substrate support.

[0022] In one exemplary embodiment, the first applying step applies a negative voltage as a first pulse voltage to the substrate support.

[0023] In one exemplary embodiment, the second applying step applies a negative voltage to the upper electrode as a second pulse voltage.

[0024] In one exemplary embodiment, a plasma processing apparatus is provided, comprising: a chamber; a substrate support disposed within the chamber and configured to support a substrate; an upper electrode disposed within the chamber facing the substrate support; and a controller, wherein the controller performs control to place the substrate on the substrate support, supply a process gas for processing the substrate into the chamber, supply a high frequency wave to the upper electrode or the substrate support to generate plasma of the process gas within the chamber, and periodically apply a first pulse voltage to the substrate support at a first period during the period during which the high frequency wave is supplied, and periodically apply a second pulse voltage to the upper electrode at a second period that is an integer fraction of the first period during the period during which the high frequency wave is supplied.

[0025] 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.

[0026] FIG. 1 is a schematic diagram illustrating a substrate processing apparatus 1 according to an exemplary embodiment. The substrate processing apparatus 1 is a capacitively coupled plasma processing apparatus. The substrate processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, an exhaust system 40, and a controller 50. The substrate 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 exemplary 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 has at least one gas inlet for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space. The sidewall 10a is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the plasma processing chamber 10 housing.

[0027] FIG. 2 is a partially enlarged view showing an example of a substrate support unit 11 included in the substrate processing apparatus 1. The substrate support unit 11 includes a main body 111 and a ring assembly 112. The main body 111 includes a base 113, an electrostatic chuck 114, and an electrode plate 117. The main body 111 also has a central region (substrate support surface) 111a for supporting a substrate (wafer) W and an annular region (ring support surface) 111b for supporting the ring assembly 112. 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. The base 113 may include a conductive member. The conductive member of the base 113 can function as a lower electrode. The electrostatic chuck 114 is disposed on a base. The upper surface of the electrostatic chuck 114 has a substrate support surface 111a. The ring assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring.

[0028] The electrostatic chuck 114 includes a chuck electrode 115 and a bias electrode 116 therein. The chuck electrode 115 includes an electrode 115a provided between the substrate support surface 111a and the base 113. The electrode 115a may be a planar electrode corresponding to the shape of the substrate support surface 111a. The chuck electrode 115 may also include electrodes 115b and 115c provided between the ring assembly 112 and the base 113. The electrodes 115b and 115c may be annular electrodes corresponding to the shape of the ring assembly 112. The electrode 115c is provided outside the electrode 115b. The bias electrode 116 includes an electrode 116a provided between the electrode 115a (or the substrate support surface 111a) and the base 113. The electrode 116a may be a planar electrode corresponding to the shape of the substrate support surface 111a and / or the electrode 115a. The bias electrode 116 may also include an electrode 116 b provided between the ring assembly and the base 113 .

[0029] When a conductive member included in the base 113 functions as the lower electrode, the electrostatic chuck 114 does not need to include the bias electrode 116. Furthermore, the chuck electrode 115 may function as the lower electrode. When the chuck electrode 115 functions as the lower electrode, the electrostatic chuck 114 does not need to include the bias electrode 116. Furthermore, the electrostatic chuck 114 may be configured such that a portion including the electrodes 115a and 116a and a portion including the electrodes 115b and 115c and the electrode 116b are separate components.

[0030] Although not shown, the substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 114, 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 path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111 a.

[0031] Returning to FIG. 1 , the showerhead 13 is configured to introduce at least one processing 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 processing 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 a conductive member. The conductive member of the showerhead 13 functions as an upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0032] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one exemplary 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 one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.

[0033] 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), such as a source RF signal and a bias RF signal, to the conductive members of the substrate support 11 and / or the conductive members of the showerhead 13. This causes plasma to be formed from at least one process gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate plasma from one or more process gases in the plasma processing chamber 10. Furthermore, supplying a bias RF signal to the conductive members of the substrate support 11 generates a bias potential on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0034] In one exemplary 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 a conductive member of the substrate support 11 and / or a conductive member of the showerhead 13 via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one exemplary embodiment, the source RF signal is a continuous wave or pulse wave including a high frequency wave having a frequency in the range of 13 MHz to 150 MHz. In one exemplary 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 the conductive member of the substrate support 11 and / or the showerhead 13. The one or more source RF signals may be supplied to the base 113, the chuck electrode 115, or the bias electrode 116 of the substrate support 11. The second RF generator 31b is coupled to the conductive member of the substrate support 11 via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). In one exemplary embodiment, the bias RF signal has a lower frequency than the source RF signal. In one exemplary embodiment, the bias RF signal is a continuous wave or pulsed wave including a high frequency having a frequency in the range of 400 kHz to 13.56 MHz. In one exemplary 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 the base 113, the chuck electrode 115, or the bias electrode 116 of the substrate support 11. 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 exemplary embodiment, the first DC generator 32a is connected to a conductive member of the substrate support 11 and configured to generate a first DC signal. The generated first bias DC signal is applied to the conductive member of the substrate support 11. In one exemplary embodiment, the first DC signal may be applied to the base 113 of the substrate support 11, the chuck electrode 115, or the electrode 116a and / or electrode 116b included in the bias electrode 116. In one exemplary embodiment, the second DC generator 32b is connected to a conductive member of the showerhead 13 and configured to generate a second DC signal. The generated second DC signal is applied to the conductive member of the showerhead 13. In various embodiments, at least one of the first and second DC signals may be pulsed. 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. The first DC signal and the second DC signal may be generated such that one frequency is an integer multiple of the other frequency. For example, the second DC generating unit 31b may generate the second DC signal in synchronization with the period of the first DC signal. The first DC signal and the second DC signal have a frequency of, for example, 400 kHz. The first DC signal and the second DC signal may be generated in synchronization with the period of the source RF signal and / or the bias RF signal.

[0036] The DC power supply 32 generates a DC voltage applied to electrodes 115a, 115b, and 115c included in the chuck electrode 115 (see FIG. 2). The electrodes 115b and 115c may form a bipolar electrostatic chuck. Alternatively, the electrodes 115a, 115b, and 115c may be integrally formed. The DC power supply 32 may be configured to apply different DC voltages to the electrodes 115a, 115b, and 115c, respectively, or may be configured to apply the same DC voltage to the electrodes 115a, 115b, and 115c. Note that the power supply 30 may include a power supply that generates the voltage applied to the chuck electrode 115, separate from the DC power supply 32.

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

[0038] The control unit 50 processes computer-executable instructions that cause the substrate processing apparatus 1 to perform various processes described in this disclosure. The control unit 50 may be configured to control each element of the substrate processing apparatus 1 to perform the various processes described herein. In one exemplary embodiment, part or all of the control unit 50 may be provided as part of a device configuration external to the substrate processing apparatus 1. The control unit 50 may include, for example, a computer 50a. The computer 50a may include, for example, a processing unit (CPU: Central Processing Unit) 50a1, a memory unit 50a2, and a communication interface 50a3. The processing unit 50a1 may be configured to perform various control operations based on programs stored in the memory unit 50a2. The memory unit 50a2 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 50a3 may communicate with other components of the substrate processing apparatus 1 via a communication line such as a local area network (LAN).

[0039] The plasma formed 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), or surface wave plasma (SWP). 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. Therefore, the AC signal includes a radio frequency (RF) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 200 kHz to 150 MHz.

[0040] Fig. 3 is a flowchart showing a substrate processing method (hereinafter also referred to as "this processing method") according to an example embodiment. Fig. 4 is a timing chart showing an example of periods during which the source RF signal, the first DC signal, and the second DC signal are supplied or applied and stopped in this processing method.

[0041] FIG. 4 shows an example in which pulse waves are used as the source RF signal and the first and second DC signals. That is, as an example, the source RF signal is a pulse wave including an electrical pulse during the H period. The first and second DC signals are also pulse waves having an electrical pulse during the H period. In FIG. 4, the horizontal axis represents time. In FIG. 5, the vertical axis represents the power level of the source RF signal (as an example, the effective value of the power of the source RF signal) and the voltage levels of the first and second DC signals (as an example, the effective values ​​of the absolute values ​​of the voltages of the first and second DC signals). "L1" in the source RF signal indicates that the source RF signal is not supplied or is lower than the power level indicated by "H1." "L2" and "L3" in the first and second DC signals indicate that the first and second DC signals are not supplied or are lower than the voltage levels indicated by "H2" and "H3," respectively.

[0042] This processing method (see FIG. 3) includes the steps of placing a substrate W on a substrate support 11 (ST1), supplying a processing gas into the plasma processing chamber 10 (ST2), supplying a source RF signal (an example of high frequency) to the lower electrode (ST3), applying a pulse voltage (ST4), stopping the supply of the source RF signal (ST5), determining the completion of etching (ST6), and stopping the supply of the processing gas (ST7).

[0043] In step ST1, a substrate W is placed on a substrate support 11. The substrate W may be, for example, a substrate in which a base film, a film to be etched by this processing method, a mask film having a predetermined pattern, etc. are laminated on a silicon wafer. The film to be etched may be, for example, a dielectric film, a semiconductor film, a metal film, etc.

[0044] In step ST2, a processing gas is supplied into the plasma processing chamber 10. The processing gas is a gas used to etch the film to be etched formed on the substrate W. The type of processing gas may be appropriately selected based on the material of the film to be etched, the material of the mask film, the material of the base film, the pattern of the mask film, the etching depth, etc.

[0045] In step ST3, a source RF signal is supplied to the substrate support 11. The source RF signal is a pulse wave having an electric pulse in an H period (see FIG. 4). Each electric pulse included in the source RF signal includes a high-frequency continuous wave. The high-frequency wave has a frequency, for example, in the range of 13 MHz to 150 MHz. When the source RF signal is supplied to the substrate support 11, plasma is formed from the processing gas supplied into the plasma processing chamber 10. In another embodiment, the source RF signal may be supplied to an upper electrode included in the showerhead 13.

[0046] In step ST4, an electric pulse is applied to the upper electrode and the substrate support 11. Step ST4 includes a step (ST41) of applying a first DC signal to the substrate support 11, and a step (ST42) of applying a second DC signal to the upper electrode included in the shower head 13. Step ST3, step ST41, and step ST42 may be started simultaneously or at different times.

[0047] The first DC signal is a pulse wave having an electric pulse in a period H. That is, in step ST41, the electric pulse included in the first DC signal is applied to the substrate support part 11 periodically.

[0048] The second DC signal is a pulse wave having an electric pulse in a period H. That is, in step ST42, the electric pulse included in the second DC signal is periodically applied to the upper electrode.

[0049] In step ST5, the supply of the source RF signal that has been supplied to the substrate support part 11 is stopped. This ends the H period and starts a period H1 during which the supply of the source RF signal is stopped (see FIG. 4). The power of the source RF signal in the L period is lower than the power of the source RF signal in the H period. Furthermore, the power of the source RF signal in the L period may be 0 W (watts). Furthermore, the supply of the first pulse voltage P1 and the second pulse voltage P2 may also be stopped in the L period.

[0050] In step ST6, it is determined whether or not to terminate the etching process of the film to be etched. If the etching process is to be continued, the process returns to step ST3, and a new H period is started. On the other hand, if the etching process is to be terminated, the supply of the processing gas is stopped in step ST7, and the etching process is terminated.

[0051] 5 to 11 are timing charts showing examples of the timing at which the first pulse voltage P1 and the second pulse voltage P2 are periodically applied during period H. The relationship between the source RF signal and the first and second DC signals in step ST4 (see FIG. 3) will be described with reference to FIGS.

[0052] 5 to 11, the horizontal axis represents time. The amplitude in the timing charts represents the power of the source RF signal, the voltage of the first DC signal, and the voltage of the second DC signal. During the H period shown in FIGS. 5 to 11, the power of the source RF signal varies at a constant frequency (for example, a frequency within a range of 13 MHz to 150 MHz).

[0053] 5 to 11, the first DC signal is a square wave whose voltage is VH1 or VL1. The second DC signal is a square wave whose voltage is VH2 or VL2. For convenience of explanation, the voltage of the first DC signal becoming VL1 is also referred to as "applying a first pulse voltage P1," and the pulses included in the first DC signal are also referred to as "first pulse voltage P1." The voltage of the second DC signal becoming VL2 is also referred to as "applying a second pulse voltage P2," and the pulses included in the second DC signal are also referred to as "second pulse voltage P2." The waveforms of one or more pulse voltages P1 included in the first DC signal and / or one or more pulse voltages P1 included in the second DC signal may be, in addition to a square wave, a triangular wave, a trapezoidal wave, an impulse, or any other signal whose voltage changes at a constant period and can apply a predetermined bias voltage to the upper electrode or the substrate support member 11. Moreover, the voltages VH1 and VH2 may be 0 V, and the voltages VL1 and VL2 may be negative voltages.

[0054] The example in Fig. 5 will be described. As shown in Fig. 5, when the H period starts at time t1, the voltage of the first DC signal becomes VL1, and a first pulse voltage P1 is applied to the substrate support member 11. Then, the first pulse voltage P1 is applied to the substrate support member 11 from time t1 to time t2 (period Ta1). When the first pulse voltage P1 is applied to the substrate support member 11, activated species present in the plasma are attracted to the substrate W placed on the substrate support member 11. As a result, the activated species collide with a film to be etched formed on the substrate W, and the film to be etched is etched.

[0055] At time t2, when the application of the first pulse voltage P1 is stopped, the application of the second pulse voltage P2 is started. The application of the second pulse voltage P2 may be started based on the end of the application of the first pulse voltage P1. The second pulse voltage P2 is applied to the upper electrode during a period Tb1 from time t2 to time t3.

[0056] At time t4, when a period Ta2 has elapsed since time t2, period PDa, which is one cycle of the first DC signal, ends. That is, at time t4, the voltage of the first DC signal becomes VL1 again, and the next cycle of the first DC signal begins. Also, at time t5, when a period Tb2 has elapsed since time t3, period PDb, which is one cycle of the second DC signal, ends. Also, at time t5, the voltage of the second DC signal becomes VL2 again, and the next cycle of the second DC signal begins. By repeating the above operations, step ST4 of this example is executed.

[0057] In this example, during period Ta1, when positive ions present in the plasma are attracted to the substrate W and the film to be etched is etched, the etched portion of the substrate W (for example, the bottom of a hole formed in the film to be etched) may become positively charged by the positive ions. On the other hand, when the second pulse voltage P2 is applied to the upper electrode, the positive ions present in the plasma are attracted to the upper electrode and collide with the upper electrode. When the positive ions collide with the upper electrode, secondary electrons are emitted from the upper electrode. The emitted secondary electrons are accelerated by the upper electrode, which is at a negative potential (voltage V2), and reach the substrate W. Then, the secondary electrons that have reached the substrate W eliminate or reduce the charge on the positively charged portion of the substrate W (for example, the bottom of a hole formed in the film to be etched).

[0058] Furthermore, in this example, the voltage VH2 of the second DC signal may be 0 V during the period Ta1. This suppresses the emission of secondary electrons from the upper electrode during the period Ta1, and also suppresses the electrons from being accelerated toward the substrate W by the potential of the upper electrode. As a result, during the period Ta1, the vicinity of the surface of the substrate W is suppressed from being negatively charged by electrons. This allows the secondary electrons emitted from the upper electrode during the period Tb1 to reach a positively charged portion of the substrate W (for example, the bottom of a hole formed in the film to be etched) without being decelerated near the surface of the substrate W.

[0059] Furthermore, in this example, at time t2, near the time when the application of the first pulse voltage P1 to the substrate support member 11 is stopped, the second pulse voltage P2 is applied to the upper electrode. This makes it possible to prevent the potentials of the substrate W and plasma from increasing significantly when the voltage of the first DC signal applied to the substrate support member 11 changes from VL1 to VH1 (i.e., when the application of the first pulse voltage P1 is stopped). Therefore, in this example, it is possible to reduce sputtering of the inner wall of the plasma processing chamber 10 (see FIG. 1) by the plasma with increased potential.

[0060] An example shown in Fig. 6 will be described. In the example shown in Fig. 6, the application of the second pulse voltage P2 starts at time t3, which is delayed from time t2. That is, in the example shown in Fig. 6, there is a period between period Ta1 and period Tb1 during which neither the first pulse voltage P1 nor the second pulse voltage P2 is applied. The application of the second pulse voltage P2 may start based on the fact that the application of the first pulse voltage P1 has stopped at time t2.

[0061] 6, during one cycle of the first DC signal, period PDa, the voltage is VL1 from time t1 to time t2, and then VH1 from time t2 to time t5. That is, during period Ta1, which is the period from time t1 to time t2, a first pulse voltage P1 is applied to substrate support member 11. During period Ta2, which is the period from time t2 to time t5, the application of first pulse voltage P1 to substrate support member 11 is stopped. This ends period PDa, which is one cycle of the first DC signal. At the same time, at time t5, the voltage of the first DC signal again becomes VL1, and the next cycle of the first DC signal begins.

[0062] In the example shown in FIG. 6, during one cycle of the second DC signal, period PDb, the voltage is VL2 from time t3 to time t4, and is 0 V from time t4 to time t6. That is, during period Tb1, which is the period from time t3 to time t4, the second pulse voltage P2 is applied to the upper electrode. During period Tb2, which is the period from time t4 to time t6, the application of the second pulse voltage P2 to the upper electrode is stopped. This ends period PDb, which is one cycle of the second DC signal. At the same time, at time t6, the voltage of the second DC signal becomes VL2 again, and the next cycle of the second DC signal begins. By repeating the above operations, step ST4 of this example is performed.

[0063] In this example, the second pulse voltage P2 is applied after a certain period of time has elapsed since the end of the period Ta1 during which the first pulse voltage P1 is applied. This allows secondary electrons to be efficiently emitted from the upper electrode. Furthermore, the thickness of the sheath formed between the upper electrode and the plasma increases, reducing the electron annihilation rate in the plasma. Therefore, the plasma density can be efficiently increased in the plasma processing chamber 10.

[0064] An example shown in Fig. 7 will be described. In the example shown in Fig. 7, the application of the second pulse voltage P2 is started at time t2, which is before time t3, when the period Ta1 during which the first pulse voltage P1 is applied, ends. That is, in the example shown in Fig. 7, the first pulse voltage P1 and the second pulse voltage P2 are applied with a partial overlap in time between time t2 and time t3. The application of the second pulse voltage P2 may be started based on the start of the application of the first pulse voltage P1 at time t1.

[0065] 7, during one cycle of the first DC signal, period PDa, the voltage is VL1 from time t1 to time t3, and then VH1 from time t3 to time t5. That is, during period Ta1, which is the period from time t1 to time t3, a first pulse voltage P1 is applied to substrate support member 11. During period Ta2, which is the period from time t3 to time t5, the application of first pulse voltage P1 to substrate support member 11 is stopped. This ends period PDa, which is one cycle of the first DC signal. At the same time, at time t5, the voltage of the first DC signal again becomes VL1, and the next cycle of the first DC signal begins.

[0066] 7, during one cycle of the second DC signal, period PDb, the voltage is VL2 from time t2 to time t4, and then VH2 from time t4 to time t6. That is, during period Tb1, which is the period from time t2 to time t4, the second pulse voltage P2 is applied to the upper electrode. During period Tb2, which is the period from time t4 to time t6, the application of the second pulse voltage P2 to the upper electrode is stopped. This ends period PDb, which is one cycle of the second DC signal. At the same time, at time t6, the voltage of the second DC signal again becomes VL2, and the next cycle of the second DC signal begins. By repeating the above operations, step ST4 of this example is performed.

[0067] In this example, the period Ta1 during which the first pulse voltage P1 is applied and the period Tb1 during which the second pulse voltage P2 is applied partially overlap in time. This makes it possible to further suppress the rise in the potentials of the substrate W and plasma when the period Ta1 during which the first pulse voltage P1 is applied ends. In addition, it is possible to control the timing at which the rise in the potentials of the substrate W and plasma is suppressed.

[0068] An example shown in Fig. 8 will be described. In the example shown in Fig. 8, the application of the second pulse voltage P2 starts at time t1 when the first pulse voltage P1 is applied. Furthermore, the application of the second pulse voltage P2 also stops at time t2 when the application of the first pulse voltage P1 stops. That is, in the example shown in Fig. 8, the first pulse voltage P1 and the second pulse voltage P2 are applied so as to overlap in time. The application of the second pulse voltage P2 may start based on the start of the application of the second pulse voltage P2 at time t1.

[0069] 8, during one cycle of the first DC signal, period PDa, the voltage is VL1 from time t1 to time t2, and then VH1 from time t2 to time t3. That is, during period Ta1, which is the period from time t1 to time t2, a first pulse voltage P1 is applied to substrate support member 11. During period Ta2, which is the period from time t2 to time t3, the application of first pulse voltage P1 to substrate support member 11 is stopped. This ends period PDa, which is one cycle of the first DC signal. At the same time, at time t3, the voltage of the first DC signal again becomes VL1, and the next cycle of the first DC signal begins.

[0070] 8, during one cycle of the second DC signal, period PDb, the voltage is VL2 from time t1 to time t2, and then VH2 from time t2 to time t3. That is, during period Tb1, which is the period from time t1 to time t2, the second pulse voltage P2 is applied to the upper electrode. During period Tb2, which is the period from time t2 to time t3, the application of the second pulse voltage P2 to the upper electrode is stopped. This ends period PDb, which is one cycle of the second DC signal. At the same time, at time t3, the voltage of the second DC signal again becomes VL2, and the next cycle of the second DC signal begins. By repeating the above operations, step ST4 of this example is performed.

[0071] In this example, the second pulse voltage P2 is applied during the period Ta1 during which the first pulse voltage P1 is applied. This increases the density of the generated plasma. Furthermore, electrons emitted from the plasma or the substrate are decelerated or shielded by a sheath formed between the plasma and the upper electrode. Therefore, for example, the electrons can be prevented from entering the gas inlet 13c of the shower head 13 (upper electrode), thereby suppressing discharge at the gas inlet 13c.

[0072] An example shown in FIG. 9 will be described. In the example shown in FIG. 9, the duty ratio of the second DC signal is different from the duty ratio of the first DC signal. In the example shown in FIG. 9, the period Ta1 during which the first pulse voltage P1 is applied coincides in time with the period Tb2 during which the second pulse voltage P2 is not applied. Furthermore, the period Ta2 during which the first pulse voltage P1 is not applied coincides with the period Tb1 during which the second pulse voltage P2 is applied. The application of the second pulse voltage P2 may be started based on the start of application of the first pulse voltage P1 at time t1. Furthermore, the application of the second pulse voltage P2 may be started based on the end of application of the first pulse voltage P1 at time t2.

[0073] 9, during one period PDa, which is one cycle of the first DC signal, the voltage is VL1 from time t1 to time t2, and then VH2 from time t2 to time t3. That is, during period Ta1, which is the period from time t1 to time t2, the first pulse voltage P1 is applied to the substrate support member 11. During period Ta2, which is the period from time t2 to time t3, the application of the first pulse voltage P1 to the substrate support member 11 is stopped. This ends period PDa, which is one cycle of the first DC signal. At the same time, at time t3, the voltage of the first DC signal again becomes VL1, and the next cycle of the first DC signal begins.

[0074] 9, during one cycle of the second DC signal, period PDb, the voltage is VL2 from time t2 to time t3, and then VH2 from time t3 to time t4. That is, during period Tb1, which is the period from time t2 to time t3, the second pulse voltage P2 is applied to the upper electrode. During period Tb2, which is the period from time t3 to time t4, the application of the second pulse voltage P2 to the upper electrode is stopped. This ends period PDb, which is one cycle of the second DC signal. At the same time, at time t4, the voltage of the second DC signal again becomes VL2, and the next cycle of the second DC signal begins. By repeating the above operations, step ST4 of this example is performed.

[0075] In this example, the application of the second pulse voltage P2 begins in synchronization with the end of the period Ta1 during which the first pulse voltage P1 is applied, and the application of the second pulse voltage P2 ends in synchronization with the start of the period Ta1 during which the first pulse voltage P1 is applied. This makes it possible to suppress an increase in the potential of the substrate W and the plasma and to increase the plasma density around time t2 when the application of the first pulse voltage P1 ends. Furthermore, secondary electrons generated at the upper electrode eliminate or further reduce the charge on positively charged portions of the substrate W (for example, the bottom of a hole formed in the film to be etched).

[0076] An example shown in FIG. 10 will be described. In the example shown in FIG. 10, the duty ratio of the second DC signal is different from the duty ratio of the first DC signal. Furthermore, application of the second pulse voltage P2 begins at time t2, which is before time t3, when the period Ta1 during which the first pulse voltage P1 is applied, ends. That is, in the example shown in FIG. 10, there is a period between time t2 and time t3 during which the first pulse voltage P1 and the second pulse voltage P2 are applied with a partial overlap. Application of the second pulse voltage P2 may begin based on the start of application of the first pulse voltage P1 at time t1.

[0077] 10, during one period PDa of the first DC signal, the voltage is VL1 from time t1 to time t3, and then VH1 from time t3 to time t5. That is, during period Ta1, which is the period from time t1 to time t3, a first pulse voltage P1 is applied to substrate support member 11. During period Ta2, which is the period from time t3 to time t5, the application of first pulse voltage P1 to substrate support member 11 is stopped. This ends period PDa, which is one period of the first DC signal. At the same time, at time t5, the voltage of the first DC signal again becomes VL1, and the next period of the first DC signal begins.

[0078] 10, during one cycle of the second DC signal, period PDb, the voltage is VL2 from time t2 to time t4, and then VH2 from time t4 to time t6. That is, during period Tb1, which is the period from time t2 to time t4, the second pulse voltage P2 is applied to the upper electrode. During period Tb2, which is the period from time t4 to time t6, the application of the second pulse voltage P2 to the upper electrode is stopped. This ends period PDb, which is one cycle of the second DC signal. At the same time, at time t6, the voltage of the second DC signal again becomes VL2, and the next cycle of the second DC signal begins. By repeating the above operations, step ST4 of this example is performed.

[0079] In this example, the period Ta1 during which the first pulse voltage P1 is applied and the period Ta2 during which the second pulse voltage P2 is applied partially overlap in time. This makes it possible to further suppress the rise in the potential of the substrate W and the plasma when the period Ta1 during which the first pulse voltage P1 is applied ends. Also, it is possible to control the timing for suppressing the rise in the potential of the substrate W and the plasma. Also, the second pulse voltage P2 applied during the period Tb1 makes it possible to further increase the plasma density.

[0080] An example shown in FIG. 11 will be described. In the example shown in FIG. 11, the duty ratio of the second DC signal is different from the duty ratio of the first DC signal. Furthermore, at time t1 when the first pulse voltage P1 is applied, the application of the second pulse voltage P2 is started. That is, in the example shown in FIG. 11, the first pulse voltage P1 and the second pulse voltage P2 are applied so as to overlap in time. The application of the second pulse voltage P2 may be started based on the start of application of the first pulse voltage P1 at time t1.

[0081] 11, during one period PDa of the first DC signal, the voltage is VL1 from time t1 to time t2, and then VH1 from time t2 to time t4. That is, during period Ta1, which is the period from time t1 to time t2, a first pulse voltage P1 is applied to substrate support member 11. During period Ta2, which is the period from time t2 to time t4, the application of first pulse voltage P1 to substrate support member 11 is stopped. This ends period PDa, which is one period of the first DC signal. At the same time, at time t4, the voltage of the first DC signal again becomes VL1, and the next period of the first DC signal begins.

[0082] 11, during one cycle of the second DC signal, period PDb, the voltage is VL2 from time t1 to time t3, and then VH2 from time t3 to time t4. That is, during period Tb1, which is the period from time t1 to time t3, the second pulse voltage P2 is applied to the upper electrode. During period Tb2, which is the period from time t3 to time t4, the application of the second pulse voltage P2 to the upper electrode is stopped. This ends period PDb, which is one cycle of the second DC signal. At the same time, at time t4, the voltage of the second DC signal again becomes VL2, and the next cycle of the second DC signal begins. By repeating the above operations, step ST4 of this example is performed.

[0083] In this example, the second pulse voltage P2 is applied during the period Ta1 during which the first pulse voltage P1 is applied. This increases the density of the generated plasma. Furthermore, since charging of the shower head 13 (upper electrode) can be suppressed, discharge at the gas inlet 13c, for example, can be suppressed.

[0084] 5 to 11, the voltages VH1 and VH2 may be, for example, 0 V. The voltage VL1 may be, for example, a voltage that can set the potential of the substrate W to a negative potential. The voltage VH1 may be a positive voltage or a negative voltage. The voltage VL2 may be a voltage that can set the potential of the upper electrode to a negative potential. The voltage VH2 may be a positive voltage or a negative voltage.

[0085] 5 to 11, the period of the second DC signal is the same as the period of the first DC signal. That is, in the examples described with reference to FIGS. 5 to 11, during each period PDa, which is one period of the first DC signal, there is a period Tb1 during which the second pulse voltage P2 is applied. In other examples, the period of one of the first DC signal and the second DC signal may be an integer multiple of twice or more the period of the other. That is, in other examples, the second pulse voltage P2 may be applied once every two or more periods of the first DC signal. Also, the second pulse voltage P2 may be applied twice or more times per period of the first DC signal.

[0086] In the examples shown in FIGS. 5 to 8, the first DC signal and the second DC signal have the same duty ratio. That is, the proportion of the period Ta1 in the period PDa, which is one cycle of the first DC signal, is equal to the proportion of the period Tb1 in the period PDb, which is one cycle of the second DC signal. In the examples shown in FIGS. 9 to 11, the first DC signal and the second DC signal have different duty ratios. That is, the proportion of the period Ta1 in the period PDa, which is one cycle of the first DC signal, is different from the proportion of the period Tb1 in the period PDb, which is one cycle of the second DC signal. Note that the duty ratios of the first DC signal and the second DC signal are not limited to these. For example, the duty ratios of the first DC signal and the second DC signal may be such that the periods Ta1 and Tb2 are longer than the periods Ta2 and Tb2, respectively. Furthermore, the duty ratio of the first DC signal and the second DC signal may be such that the period Ta1 is longer than the period Tb1.

[0087] The above embodiments have been described for illustrative purposes, and various modifications may be made without departing from the scope and spirit of the present disclosure. For example, the present processing method can be performed using a substrate processing apparatus using any plasma source, such as an inductively coupled plasma or a microwave plasma, in addition to the capacitively coupled substrate processing apparatus 1. [Explanation of symbols]

[0088] 1...substrate processing apparatus, 10...plasma processing chamber, 11...substrate support, 13...shower head, 20...gas supply unit, 21...gas source, 22...flow rate controller, 30...power supply, 31...RF power supply, 32...DC power supply, 40...exhaust system, 50...control unit, 111...main body, 112...ring assembly, W...substrate

Claims

1. A plasma processing method for plasma processing a substrate in a plasma processing apparatus, comprising: The plasma processing apparatus includes: a chamber; a substrate support disposed within the chamber and configured to support the substrate; an upper electrode provided in the chamber facing the substrate support; The plasma processing method comprises: placing a substrate on the substrate support; supplying a process gas into the chamber for processing the substrate; applying a high frequency wave to the upper electrode or the substrate support to generate a plasma of the processing gas within the chamber; a first applying step of periodically applying a first pulse voltage to the substrate support during a period in which the high frequency is continuously supplied; a second applying step of periodically applying a second pulse voltage to the upper electrode during the period in which the high frequency is continuously supplied; Including, The first applying step includes: starting application of the first pulse voltage at a first time point; stopping the application of the first pulse voltage at a second time point that is later than the first time point; restarting application of the first pulse voltage at a third time point that is later than the second time point; stopping the application of the first pulse voltage again at a fourth time point that is later than the third time point; Including, The second applying step includes: starting application of the second pulse voltage at the second time point; stopping the application of the second pulse voltage at a time between the second time point and the third time point; restarting application of the second pulse voltage at the fourth time point; Including, A plasma processing method, wherein a time interval from the first time point to the second time point is equal to or less than a time interval from the second time point to the third time point.

2. 2. The plasma processing method according to claim 1, wherein the step of generating the plasma comprises supplying the high frequency wave to the substrate support.

3. 3. The plasma processing method according to claim 1, wherein the first applying step applies a negative voltage as the first pulse voltage to the substrate support portion.

4. 4. The plasma processing method according to claim 1, wherein the second applying step applies a negative voltage as the second pulse voltage to the upper electrode.

5. 5. The plasma processing method according to claim 1, wherein the second applying step stops application of the second pulse voltage at the third time point.

6. a chamber; a substrate support disposed within the chamber and configured to support a substrate; an upper electrode provided in the chamber facing the substrate support; Control unit and The control unit comprises: controlling placement of a substrate on the substrate support; controlling supply of a process gas into the chamber for processing the substrate; supplying a high frequency to the upper electrode or the upper electrode to generate plasma of the processing gas within the chamber; a first application control for periodically applying a first pulse voltage to the substrate support during a period in which the high frequency power is continuously supplied; a second application control for periodically applying a second pulse voltage to the upper electrode during a period in which the high frequency is continuously supplied; Run The first application control includes: Controlling to start application of the first pulse voltage at a first time point; control to stop application of the first pulse voltage at a second time point that is later than the first time point; control to restart application of the first pulse voltage at a third time point that is later than the second time point; and stopping the application of the first pulse voltage again at a fourth time point that is later than the third time point. Including, The second application control includes: control to start application of the second pulse voltage at the second time point; control to stop application of the second pulse voltage at a time point between the second time point and the third time point; control to restart application of the second pulse voltage at the fourth time point; Including, a time interval from the first time point to the second time point is equal to or less than a time interval from the second time point to the third time point; Plasma processing equipment.

7. The plasma processing apparatus according to claim 6 , wherein the control for generating the plasma includes supplying the high frequency wave to the substrate support portion.

8. 8. The plasma processing apparatus according to claim 6, wherein the first application control applies a negative voltage as the first pulse voltage to the substrate support portion.

9. 9. The plasma processing apparatus according to claim 6, wherein the second application control applies a negative voltage as the second pulse voltage to the upper electrode.

10. 10. The plasma processing apparatus according to claim 6, wherein the second voltage application control stops application of the second pulse voltage at the third time point.

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