Plasma processing device

Abstract

Provided is a technology capable of improving processing performance with respect to a substrate in a plasma processing device. A plasma processing device (1) comprises a chamber (10), a substrate supporting portion (11) disposed in the chamber (10), an RF signal generator (31), and a voltage pulse signal generator (32) configured to generate a voltage pulse signal. The voltage pulse signal has a sequence of voltage pulses having a reference voltage level (vref) in a first period (T1) included in each of a plurality of cycles and having a first voltage level (v1) in a second period (T2) included in each of the plurality of cycles. The absolute value of the first voltage level (v1) is larger than the absolute value of the reference voltage level (vref), and each of the plurality of voltage pulses included in the sequence of voltage pulses has an ON period longer than 0 seconds and equal to or shorter than 0.5 microseconds.

Description

Plasma processing equipment

[0001] Exemplary embodiments of this disclosure relate to plasma processing apparatus.

[0002] In a plasma processing apparatus, there is a technique described in Patent Document 1 for supplying an RF signal to the upper electrode and a DC signal to the lower electrode.

[0003] Japanese Patent Publication No. 2024-013548

[0004] This disclosure provides a technology that can improve the processing performance of a substrate in a plasma processing apparatus.

[0005] A plasma processing apparatus in one exemplary embodiment of the present disclosure comprises: a chamber; a substrate support disposed within the chamber, the substrate support having a conductive base; an electrostatic chuck disposed on the conductive base; and an electrode disposed within the electrostatic chuck; an RF signal generator configured to generate an RF signal for generating plasma in the chamber; and a voltage pulse signal generator electrically connected to the electrode and configured to generate a voltage pulse signal, wherein the voltage pulse signal has a reference voltage level in a first period included in each of a plurality of cycles, and a sequence of voltage pulses having the first voltage level in a second period included in each of the plurality of cycles, the absolute value of the first voltage level is greater than the absolute value of the reference voltage level, and each of the plurality of voltage pulses included in the sequence of voltage pulses has an on period of longer than 0 seconds and of 0.5 microseconds or less.

[0006] According to one exemplary embodiment of the present disclosure, a technology can be provided that can improve the processing performance of a substrate in a plasma processing apparatus.

[0007] This is a diagram illustrating an example configuration of a plasma processing system. This is a diagram illustrating an example configuration of a plasma processing apparatus. This is a diagram illustrating an example configuration of a substrate support section. This is a diagram illustrating examples of source RF signals and voltage pulse signals in each of multiple cycles. This is a diagram illustrating an example of a pulse cycle in a voltage pulse sequence. This is a diagram illustrating an example of a change in the surface potential of the substrate when a voltage pulse signal is supplied. This is a diagram illustrating an example of a change in the surface potential of the substrate and the edge ring when a voltage pulse signal is supplied. This is a diagram illustrating an example of a second voltage pulse signal in each of multiple cycles. This is a diagram illustrating an example of a pulse cycle in a second voltage pulse sequence.

[0008] The embodiments of this disclosure are described below.

[0009] In one exemplary embodiment, a plasma processing apparatus is provided, comprising: a chamber; a substrate support disposed within the chamber, the substrate support comprising a conductive base, an electrostatic chuck disposed on the conductive base, and an electrode disposed within the electrostatic chuck; an RF signal generator configured to generate an RF signal for generating plasma within the chamber; and a voltage pulse signal generator electrically connected to the electrode and configured to generate a voltage pulse signal, wherein the voltage pulse signal has a reference voltage level in a first period included in each of a plurality of cycles, and a sequence of voltage pulses having a first voltage level in a second period included in each of the plurality of cycles, the absolute value of the first voltage level being greater than the absolute value of the reference voltage level, and each of the plurality of voltage pulses included in the sequence of voltage pulses having an on-period longer than 0 seconds and less than or equal to 0.5 microseconds.

[0010] In one exemplary embodiment, the ON period is 0.3 μs or less.

[0011] In one exemplary embodiment, the first voltage level has negative polarity.

[0012] In one exemplary embodiment, the reference voltage level has a zero voltage level.

[0013] In one exemplary embodiment, the sequence of voltage pulses has a pulse frequency of 500 kHz or higher.

[0014] In one exemplary embodiment, the sequence of voltage pulses has a pulse frequency of 2 MHz or less.

[0015] In one exemplary embodiment, the multiple cycles have a repetition frequency in the range of 1 kHz to 100 kHz.

[0016] In one exemplary embodiment, the ON period is less than 50% of one pulse cycle in the sequence of voltage pulses.

[0017] In one exemplary embodiment, the ON period is less than 20% of one pulse cycle in the sequence of voltage pulses.

[0018] In one exemplary embodiment, a plasma processing apparatus is provided, comprising: a plasma processing chamber; a substrate support portion disposed within the plasma processing chamber; an electrode disposed within the substrate support portion; and a voltage pulse signal generator electrically connected to the electrode and configured to generate a voltage pulse signal, wherein the voltage pulse signal has a sequence of voltage pulses, and each of the plurality of voltage pulses included in the sequence of voltage pulses has an on-period longer than 0 seconds and of 0.5 microseconds or less.

[0019] In one exemplary embodiment, the plasma processing apparatus according to claim 10, wherein the ON period is 0.3 μs or less.

[0020] In one exemplary embodiment, the sequence of voltage pulses has a first voltage level, and the first voltage level has a negative polarity.

[0021] In one exemplary embodiment, the sequence of voltage pulses has a pulse frequency of 500 kHz or higher.

[0022] In one exemplary embodiment, the sequence of voltage pulses has a pulse frequency of 2 MHz or less.

[0023] In one exemplary embodiment, the ON period is less than 50% of one pulse cycle in the sequence of voltage pulses.

[0024] In one exemplary embodiment, the ON period is less than 20% of one pulse cycle in the sequence of voltage pulses.

[0025] Hereinafter, each embodiment of this disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are denoted by the same reference numeral, and redundant explanations are omitted. Unless otherwise specified, positional relationships such as top, bottom, 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 actual ratios are not limited to those shown.

[0026] <Example of a Plasma Processing System> Figure 1 is a diagram illustrating an example of the configuration 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 unit 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 outlet for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas outlet is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is located in the plasma processing space and has a substrate support surface for supporting a substrate.

[0027] The plasma generation unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), ECR (Electron Cyclotron Resonance) plasma, helicon wave excited plasma (HWP), or surface wave plasma (SWP), etc. Various types of plasma generation units, including AC (Alternating Current) plasma generation units and DC (Direct Current) plasma generation units, may also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0028] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 may be configured to control the elements of the plasma processing apparatus 1 to perform the 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 is implemented, for example, by a computer 2a. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The functions realized by the processing unit 2a1 described herein may be implemented in a circuit or processing circuit, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), a conventional circuit, and / or a combination thereof, programmed to realize the described functions. The processor is considered to be a circuit or processing circuit, including transistors and other circuits. The processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be pre-stored in the storage unit 2a2 or retrieved via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).In this disclosure, circuits, units, and means are hardware programmed to perform or configured to perform the functions described. Such hardware may be any hardware described in this disclosure, or any hardware known to be programmed to perform or execute the functions described. If such hardware is a processor that is considered to be a type of circuit, such circuit, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0029] The following describes an example configuration of a capacitively coupled plasma processing apparatus as an example of a plasma processing apparatus 1. Figure 2 is a diagram illustrating an example configuration of a capacitively coupled plasma processing apparatus.

[0030] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is located inside the plasma processing chamber 10. The shower head 13 is located above the substrate support unit 11. In one embodiment, the shower head 13 constitutes 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 shower head 13, the side walls 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support unit 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0031] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the 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 portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the ring support surface for supporting the ring assembly 112.

[0032] 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 placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic chuck electrode 1111b placed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also called a clamping electrode. In one embodiment, the electrostatic chuck electrode 1111b is electrically connected or coupled to a chuck power supply. The chuck power supply may be a DC power supply or an AC power supply. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Furthermore, other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have an annular region 111b. In this case, the ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulating member, or it may be placed on both the electrostatic chuck 1111 and the annular insulating member. In addition, at least one bias electrode, which is electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed inside the ceramic member 1111a. In this case, at least one bias electrode functions as a lower electrode. Also, the conductive member of the base 1110 and the bias electrode inside the ceramic member 1111a may function as multiple lower electrodes. In one embodiment, the first voltage generation unit 32a, which functions as a voltage pulse generation unit described later, is electrically connected or coupled to the bias electrode inside the ceramic member 1111a, and the first RF generation unit 31a, described later, is electrically connected or coupled to the conductive member of the base 1110. Furthermore, the electrostatic chuck electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0033] 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 covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are formed of an insulating material.

[0034] The substrate support section 11 may also include a temperature control 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 control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0035] 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 a plurality of gas inlet ports 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 through the plurality of gas inlet ports 13c. The showerhead 13 also includes at least one 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 side wall 10a.

[0036] 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 processing gas to the shower head 13 from a corresponding gas source 21 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of at least one processing gas.

[0037] The power supply system 30 includes a power supply 31 that is electrically connected or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected or coupled to the plasma processing chamber 10 via at least one impedance matcher. The impedance matcher may be a mechanically controlled matcher or an electronically controlled matcher. The 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. Thereby, plasma is generated from at least one process gas supplied to the plasma processing space 10s. Therefore, the power supply 31 can function as at least a part of the plasma generation unit 12. Also, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and the ion component in the formed plasma can be drawn into the substrate W.

[0038] The power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode, and is configured to generate a source RF signal (source RF power) for generating plasma in the plasma processing space 10s. In one embodiment, the first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matcher. In one embodiment, the source RF signal has a frequency within the range of 10 MHz to 150 MHz. In one embodiment, the first RF generation unit 31a may be configured to generate a plurality of 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.

[0039] The second RF generation unit 31b is electrically connected or coupled to at least one lower electrode and is configured to generate a bias RF signal (bias RF power). In one embodiment, the second RF generation unit 31b is electrically connected or coupled to at least one lower electrode via at least one impedance matcher. When the first RF generation unit 31a is electrically connected or coupled to the lower electrode, the second RF generation unit 31b may be electrically connected or coupled to the same lower electrode or may be electrically connected or coupled to another lower electrode. 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 within the range of 100 kHz to 60 MHz. In one embodiment, the second RF generation unit 31b may be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0040] Also, the power supply system 30 may include a power supply 32 that is electrically connected or coupled to the plasma processing chamber 10. The power supply 32 includes a first voltage generation unit 32a and a second voltage generation unit 32b. In one embodiment, the first voltage generation unit 32a is electrically connected or coupled to at least one lower electrode and is configured to generate a first voltage signal. The generated first voltage signal is applied to at least one lower electrode. In one embodiment, the second voltage generation unit 32b is electrically connected or coupled to at least one upper electrode and is configured to generate a second voltage signal. The generated second voltage signal is applied to at least one upper electrode.

[0041] In various embodiments, the first and / or second voltage signals may be pulsed. In this case, the first voltage generation unit 32a and / or the second voltage generation unit 32b function as voltage pulse generation units configured to generate a sequence of voltage pulses. Thus, the sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. In one embodiment, the sequence of voltage pulses has a plurality of cycles, each cycle including a burst of voltage pulses in a first period and a constant reference voltage in a second period. That is, in the sequence of voltage pulses, the burst of voltage pulses is repeated. The absolute value of the voltage level of the voltage pulse is greater than the absolute value of the voltage level of the reference voltage. The voltage pulse may have an arbitrary waveform having a rectangle, trapezoid, triangle, or a combination thereof, and the arbitrary waveform may change over time. The voltage pulse may have positive polarity or negative polarity. The sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. The first and second voltage generation units 32a and 32b may be provided in addition to the power supply 31, and the first voltage generation unit 32a may be provided in place of the second RF generation unit 31b.

[0042] The exhaust system 40 may be connected to, for example, a gas outlet 10e located 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 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.

[0043] As described above, the substrate support portion 11 has an electrode (lower electrode). In one embodiment, as shown in Figure 3, the substrate support portion 11 may have a substrate bias electrode 200, which is an example of an electrode, within the electrostatic chuck 1111. The substrate bias electrode 200 is positioned below the substrate support surface 111a of the substrate support portion 11. The substrate bias electrode 200 may be a conductive base 1110.

[0044] In one embodiment, the first voltage generation unit 32a may have a first voltage pulse generator 300. The first voltage pulse generator 300 is electrically connected to the substrate bias electrode 200 and is configured to generate a first voltage pulse signal and supply it to the substrate bias electrode 200. The first RF generation unit 31a is configured to generate a source RF signal and supply it to the lower electrode or the upper electrode. The first RF generation unit 31a is an example of an RF generator.

[0045] In one embodiment, as shown in Figure 4, the first voltage pulse signal has a given multiple repeating cycle C1(n) (where n is an integer). In one embodiment, each of the multiple cycles C1(n) may have a first period T1 and a second period T2 in that order. In one embodiment, the cycle C1(n) consisting of the first period T1 and the second period T2 may be repeated a given number of times. The repetition frequency of cycle C1(n) may be in the range of 1 kHz to 100 kHz.

[0046] In one embodiment, the first voltage pulse signal is set to a constant reference voltage level (v) during the first period T1. ｒｅｆ ) has. In one embodiment, the reference voltage level (v ｒｅｆ ) may be at a zero voltage level.

[0047] In one embodiment, the first voltage pulse signal has a sequence of voltage pulses SC1 during a second period T2. The sequence of voltage pulses SC1 includes a plurality of voltage pulses DP1. As shown in Figure 5, each of the plurality of voltage pulses DP1 has an on-period Ton having a first voltage level (v1). Each of the plurality of voltage pulses DP1 has a reference voltage level (v ｒｅｆ It has an off period Toff which has ). In one embodiment, the first voltage level (v1) has negative polarity. The absolute value of the first voltage level (v1) is the reference voltage level (v ｒｅｆ It is greater than the absolute value of the reference voltage level (v). ｒｅｆ ) may be at a zero voltage level.

[0048] The ON period Ton is longer than 0 seconds and less than or equal to 0.5 microseconds. The ON period Ton may be longer than 0 seconds and less than or equal to 0.3 microseconds.

[0049] The voltage pulse sequence SC1 has a pulse frequency of 500 kHz or higher. That is, in the voltage pulse sequence SC1, the voltage pulse DP1 is performed at a pulse frequency of 500 kHz or higher. The voltage pulse sequence SC1 may have a pulse frequency of 2 MHz or lower.

[0050] The ON period Ton is less than 50% of one pulse cycle PC(m) (where m is an integer) of the voltage pulse sequence SC1. That is, the ON period Ton of each of multiple pulse cycles PC(m) is shorter than the OFF period Toff, and the pulse duty cycle (Ton / (Ton + Toff) × 100) is less than 50%. The ON period Ton may be less than 20% of the pulse cycle PC(m) of the voltage pulse sequence SC1.

[0051] In one embodiment, each of the multiple voltage pulses DP1 may have a rectangular pulse waveform, or it may have various pulse waveforms such as trapezoidal, triangular, or a combination thereof.

[0052] In one embodiment, the source RF signal generated by the first RF generation unit 31a has a common cycle C1(n) with the voltage pulse signal. The source RF signal has a first power level (p1) during a first period T1 and a second power level (p2) during a second period T2. The first power level (p1) may be zero power level. The first power level (p1) may be greater than zero power level. The second power level (p2) is greater than the first power level (p1).

[0053] In one embodiment, as shown in Figure 3, the substrate support portion 11 has a ring support surface 111b that surrounds the substrate W on the substrate support surface 111a. An edge ring 350 is placed on the ring support surface 111b. The edge ring 350 is included in the ring assembly 112. In one embodiment, the substrate support portion 11 may have a ring bias electrode 400, which is an example of an electrode, inside the electrostatic chuck 1111. The ring bias electrode 400 is placed below the ring support surface 111b inside the electrostatic chuck 1111.

[0054] The first voltage generation unit 32a may have a second voltage pulse generator 410. The second voltage pulse generator 410 is electrically connected to the ring bias electrode 400 and is configured to generate and supply a second voltage pulse signal to the ring bias electrode 400. The second voltage pulse signal may be the same as the first voltage pulse signal. The second voltage pulse signal is generated at a reference voltage level (v) during a first period included in each of a plurality of cycles C1(n). ｒｅｆ ) may have a sequence SC1 of voltage pulses during the second period T2.

[0055] <Example of Plasma Processing> The plasma processing apparatus 1 performs plasma processing on a substrate. The plasma processing includes etching processing, which involves etching a film on the substrate W using plasma. The etching processing includes forming a plurality of holes in the film on the substrate (film to be etched). In one embodiment, the plasma processing is performed by the control unit 2 in the plasma processing apparatus 1.

[0056] In the plasma processing apparatus 1 shown in Figure 2, first, a substrate W is transported into the chamber 10 by a transport arm, placed on a substrate support section 11 by a lifter, and held by suction on the substrate support section 11. The substrate W provided at this time has a film to be etched and a mask on the film to be etched, and the mask may have at least one opening.

[0057] The temperature of the substrate support section 11 or the substrate W is adjusted by a temperature control module. In one embodiment, a refrigerant is supplied from a chiller unit to the flow path 1110a of the substrate support section 11.

[0058] The processing gas is supplied into the chamber 10 by the gas supply unit 20 through the shower head 13. The processing gas contains gases that generate active species necessary for etching the substrate W.

[0059] A source RF signal is generated by the first RF generation unit 31a and supplied to the upper or lower electrode of the chamber 10. This generates plasma from the processing gas on the substrate support unit 11 within the chamber 10. A first voltage pulse signal is generated by the first voltage pulse generator 300 and supplied to the substrate bias electrode 200 of the substrate support unit 11. This draws ionic components in the plasma into the substrate. Furthermore, a second voltage pulse signal is generated by the second voltage pulse generator 410 and supplied to the ring bias electrode 400 of the substrate support unit 11. This draws ionic components in the plasma towards the edge ring 350 around the substrate. In this way, the film to be etched on the substrate W is etched.

[0060] In the etching process of the substrate W, as shown in Figure 4, the source RF signal and the first voltage pulse signal have a cycle C1(n) that is repeated multiple times. In the first period T1 included in each of the multiple cycles C1(n), the source RF signal has a first power level (p1). The first power level (p1) may be zero power level. The first voltage pulse signal has a reference voltage level (v ｒｅｆ ) has a reference voltage level (v ｒｅｆ ) may be at a zero voltage level.

[0061] In the second period T2 included in each of the plurality of cycles C1(n), the source RF signal has a second power level (p2). The second power level (p2) is greater than the first power level (p1). The first voltage pulse signal has a sequence SC1 of voltage pulses. As shown in FIG. 5, each of the plurality of voltage pulses DP1 has an on-period Ton having a first voltage level (v1). The on-period Ton is longer than 0 seconds and not more than 0.5 μs. The on-period Ton is less than 50% of one pulse cycle PC(m) of the sequence SC1 of voltage pulses. The sequence SC1 of voltage pulses has a pulse frequency of 500 kHz or more. The first voltage level (v1) may be constant in the plurality of cycles C1(n).

[0062] In the first period T1, the second voltage pulse signal has a reference voltage level (v ｒｅｆ ), and in the second period T2, it may have a sequence SC1 of voltage pulses similar to the first voltage pulse signal. That is, as shown in FIG. 8, in the first period T1 included in each of the plurality of cycles C1(n), the second voltage pulse signal has a second reference voltage level (v ｒｅｆ ). The second reference voltage level (v ｒｅｆ ) may be a zero voltage level. The second reference voltage level (v ｒｅｆ ) may be the same as the reference voltage level (v ｒｅｆ ) of the first voltage pulse signal. In the second period T2 included in each of the plurality of cycles C1(n), the second voltage pulse signal has a sequence SC2 of second voltage pulses having a second voltage level. Each of the plurality of voltage pulses DP2 included in the sequence SC2 of second voltage pulses has an on-period Ton having a second voltage level (v2), as shown in FIG. 9. The on-period Ton is longer than 0 seconds and not more than 0.5 μs. The on-period Ton is less than 50% of one pulse cycle PC2(m) of the sequence SC2 of second voltage pulses. The sequence SC2 of second voltage pulses has a pulse frequency of 500 kHz or more. The second voltage level (v2) may be constant in the plurality of cycles C1(n).

[0063] Then, a cycle C1(n) consisting of a first period T1 and a second period T2 is repeated a given number of times. In this way, the film to be etched on the substrate is etched.

[0064] According to this exemplary embodiment, the plasma processing apparatus 1 comprises a chamber 10, a substrate support 11, a first RF generation unit 31a, and a first voltage generation unit 32a. The first voltage generation unit 32a is electrically connected to the substrate bias electrode 200 and configured to generate a voltage pulse signal. The voltage pulse signal generates a reference voltage level (v) during a first period T1 included in each of a plurality of cycles C1(n). ｒｅｆ The system has a sequence SC1 of voltage pulses having a first voltage level (v1) in a second period T2 included in each of the multiple cycles C1(n). The absolute value of the first voltage level (v1) is equal to the reference voltage level (v ｒｅｆ It is greater than the absolute value of ). Each of the multiple voltage pulses DP1 included in the voltage pulse sequence SC1 has an on-period Ton that is longer than 0 seconds and less than or equal to 0.5 μs.

[0065] According to this exemplary embodiment, the on-period Ton of each voltage pulse DP1 included in the voltage pulse sequence SC1 is 0.5 μs or less. This allows multiple voltage pulses DP1 with short on-periods Ton to be supplied to the substrate bias electrode 200. Since the plasma sheath is thought to grow immediately after the start of supplying the voltage pulse signal, supplying multiple voltage pulses DP1 with short on-periods Ton effectively promotes plasma sheath growth and increases the ion flux on the substrate. As a result, the etching shape of the film to be etched by plasma processing can be improved.

[0066] As shown in Figure 6, the surface potential Vw of the substrate decreases over time in each voltage pulse DP1. In this embodiment, the short on-period Ton suppresses the decrease in the surface potential Vw of the substrate in each voltage pulse DP1. As a result, plasma processing of the substrate is performed stably.

[0067] Furthermore, as shown in Figure 7, the difference between the substrate surface potential Vw and the edge ring surface potential Vr increases over time in each voltage pulse DP1. According to this embodiment, by shortening the on-period Ton, the difference between the substrate surface potential Vw and the edge ring surface potential Vr generated in each voltage pulse DP1 can be reduced. As a result, the etching shape at the outer periphery of the substrate is improved, and consequently, the uniformity within the substrate surface during plasma processing can be improved.

[0068] According to this exemplary embodiment, the voltage pulse sequence SC1 has a pulse frequency of 500 kHz or higher, so the voltage pulse DP1 is repeated at a high frequency. This makes it possible to increase the ion flux on the substrate, and as a result, the etching shape of the film to be etched by plasma treatment can be improved.

[0069] The etchable film was etched to form multiple holes under two conditions: Condition 1 (on-period Ton of each voltage pulse DP1 in the voltage pulse sequence SC1: 0.5 μs (pulse frequency: 400 kHz)) and Condition 2 (on-period Ton of each voltage pulse DP1 in the voltage pulse sequence SC1: 0.3 μs (pulse frequency: 600 kHz)), and the variation (3σ) in the positions of the bottoms of the multiple holes was measured. The variation (3σ) in the positions of the bottoms of the multiple holes under Condition 1 was reduced by approximately 26% compared to the variation (3σ) under Condition 2. In addition, the boeing (hole diameter) under Condition 1 was reduced by approximately 9% compared to the boeing under Condition 2. This confirmed that shortening the on-period Ton of each voltage pulse DP1 tends to improve the etched shape.

[0070] In the above embodiment, the voltage pulse signal, that is, the voltage pulse signal in which each of the plurality of voltage pulses DP1 included in the voltage pulse sequence SC1 has an on period Ton of 0.5 μs or less, may be supplied to the substrate bias electrode 200 and the ring bias electrode 400, or to the ring bias electrode 400.

[0071] In the embodiments described above, a capacitively coupled plasma apparatus was used as an example, but the invention is not limited to this and may be applied to other plasma apparatuses. For example, an inductively coupled plasma apparatus may be used instead of a capacitively coupled plasma apparatus. In this case, the inductively coupled plasma apparatus includes an antenna and a lower electrode. The lower electrode is located within the substrate support, and the antenna is located above or above the chamber. In one embodiment, the first RF generation unit 31a may be electrically connected to the antenna, and the first voltage generation unit 32a may be electrically connected to the lower electrode.

[0072] Embodiments of this disclosure further include the following embodiments:

[0073] (Note 1) A plasma processing apparatus comprising: a chamber; a substrate support portion disposed within the chamber, the substrate support portion having a conductive base, an electrostatic chuck disposed on the conductive base, and an electrode disposed within the electrostatic chuck; an RF signal generator configured to generate an RF signal for generating plasma within the chamber; and a voltage pulse signal generator electrically connected to the electrode and configured to generate a voltage pulse signal, wherein the voltage pulse signal has a reference voltage level in a first period included in each of a plurality of cycles, and a sequence of voltage pulses having a first voltage level in a second period included in each of the plurality of cycles, the absolute value of the first voltage level is greater than the absolute value of the reference voltage level, and each of the plurality of voltage pulses included in the sequence of voltage pulses has an on period longer than 0 seconds and of 0.5 μs or less.

[0074] (Note 2) The plasma processing apparatus according to Note 1, wherein the ON period is 0.3 μs or less.

[0075] (Note 3) The plasma processing apparatus according to Note 1 or 2, wherein the first voltage level has negative polarity.

[0076] (Note 4) The plasma processing apparatus according to any one of Notes 1 to 3, wherein the reference voltage level has a zero voltage level.

[0077] (Note 5) The plasma processing apparatus according to any one of Notes 1 to 3, wherein the sequence of voltage pulses has a pulse frequency of 500 kHz or higher.

[0078] (Note 6) The plasma processing apparatus according to any one of Notes 1 to 5, wherein the sequence of voltage pulses has a pulse frequency of 2 MHz or less.

[0079] (Note 7) The plasma processing apparatus according to any one of Notes 1 to 6, wherein the plurality of cycles have a repetition frequency in the range of 1 kHz to 100 kHz.

[0080] (Note 8) The plasma processing apparatus according to any one of Notes 1 to 7, wherein the ON period is less than 50% of one pulse cycle in the sequence of voltage pulses.

[0081] (Note 9) The plasma processing apparatus according to any one of Notes 1 to 7, wherein the ON period is less than 20% of one pulse cycle in the sequence of voltage pulses.

[0082] (Note 10) The plasma processing apparatus according to any one of Notes 1 to 9, wherein the first voltage level is constant in the plurality of cycles.

[0083] (Note 11) The plasma processing process according to any one of Notes 1 to 10, further comprising: an edge ring arranged to surround a substrate on the electrostatic chuck; a ring electrode arranged below the edge ring within the electrostatic chuck; and a second voltage pulse signal generator electrically connected to the ring electrode and configured to generate a second voltage pulse signal, wherein the second voltage pulse signal has a second reference voltage level in the first period and a sequence of second voltage pulses having the second voltage level in the second period, the absolute value of the second voltage level is greater than the absolute value of the second reference voltage level, and each of the plurality of voltage pulses included in the sequence of second voltage pulses has an on period of longer than 0 seconds and of 0.5 μs or less.

[0084] (Note 12) The plasma processing apparatus according to any one of Notes 1 to 11, wherein the RF signal has a first power level during the first period and a second power level during the second period, the second power level being greater than the first power level.

[0085] (Note 13) A plasma processing apparatus comprising: a plasma processing chamber; a substrate support portion disposed within the plasma processing chamber; an electrode disposed within the substrate support portion; and a voltage pulse signal generator electrically connected to the electrode and configured to generate a voltage pulse signal, wherein the voltage pulse signal has a sequence of voltage pulses, and each of the plurality of voltage pulses included in the sequence of voltage pulses has an on-period longer than 0 seconds and of 0.5 μm seconds or less.

[0086] (Note 14) The plasma processing apparatus according to Note 13, wherein the ON period is 0.3 μs or less.

[0087] (Note 15) The plasma processing apparatus according to Note 13 or 14, wherein the sequence of voltage pulses has a first voltage level, and the first voltage level has negative polarity.

[0088] (Note 16) The plasma processing apparatus according to any one of Notes 13 to 15, wherein the sequence of voltage pulses has a pulse frequency of 500 kHz or higher.

[0089] (Note 17) The plasma processing apparatus according to any one of Notes 13 to 16, wherein the sequence of voltage pulses has a pulse frequency of 2 MHz or less.

[0090] (Note 18) The plasma processing apparatus according to any one of Notes 13 to 17, wherein the ON period is less than 50% of one pulse cycle in the sequence of voltage pulses.

[0091] (Note 19) The plasma processing apparatus according to any one of Notes 13 to 17, wherein the ON period is less than 20% of one pulse cycle in the sequence of voltage pulses.

[0092] (Note 20) The plasma processing apparatus according to any one of Notes 13 to 19, wherein the first voltage level is constant in the plurality of cycles.

[0093] (Note 21) The plasma processing process according to any one of Notes 13 to 20, further comprising: an edge ring arranged to surround a substrate on the substrate support portion; a ring electrode arranged below the edge ring within the substrate support portion; and a second voltage pulse signal generator electrically connected to the ring electrode and configured to generate a second voltage pulse signal, wherein the second voltage pulse signal has a second reference voltage level in the first period and a sequence of second voltage pulses having the second voltage level in the second period, the absolute value of the second voltage level is greater than the absolute value of the second reference voltage level, and each of the plurality of voltage pulses included in the sequence of second voltage pulses has an on period of longer than 0 seconds and of 0.5 μs or less.

[0094] (Note 22) The plasma apparatus according to any one of Notes 13 to 21, further comprising an RF signal generator configured to generate an RF signal for generating plasma in the chamber, wherein the RF signal has a first power level in the first period and a second power level in the second period, the second power level being greater than the first power level.

[0095] The embodiments described above are for illustrative purposes only and are not intended to limit the scope of this disclosure. The embodiments described above can be modified in various ways without departing from the scope and spirit of this disclosure. For example, some components of one embodiment can be added to other embodiments, or some components of one embodiment can be replaced with corresponding components of other embodiments.

[0096] 1...Plasma processing apparatus, 10...Chamber, 11...Substrate support section, 31a...First RF generation section, 32a...First voltage generation section, 200...Substrate bias electrode, 300...First voltage pulse generator, C1(n)...Cycle, T1...First period, T2...Second period, SC1...Voltage pulse sequence, DP1...Voltage pulse, Ton...On period, W...Substrate

Claims

1. A plasma processing apparatus comprising: a chamber; a substrate support portion disposed within the chamber, the substrate support portion having a conductive base, an electrostatic chuck disposed on the conductive base, and an electrode disposed within the electrostatic chuck; an RF signal generator configured to generate an RF signal for generating plasma within the chamber; and a voltage pulse signal generator electrically connected to the electrode and configured to generate a voltage pulse signal, wherein the voltage pulse signal has a reference voltage level in a first period included in each of a plurality of cycles, and a sequence of voltage pulses having a first voltage level in a second period included in each of the plurality of cycles, the absolute value of the first voltage level is greater than the absolute value of the reference voltage level, and each of the plurality of voltage pulses included in the sequence of voltage pulses has an on period longer than 0 seconds and of 0.5 microseconds or less.

2. The plasma processing apparatus according to claim 1, wherein the ON period is 0.3 μs or less.

3. The plasma processing apparatus according to claim 1 or 2, wherein the first voltage level has negative polarity.

4. The plasma processing apparatus according to claim 3, wherein the reference voltage level has a zero voltage level.

5. The plasma processing apparatus according to claim 3, wherein the sequence of voltage pulses has a pulse frequency of 500 kHz or higher.

6. The plasma processing apparatus according to claim 5, wherein the sequence of voltage pulses has a pulse frequency of 2 MHz or less.

7. The plasma processing apparatus according to claim 6, wherein the plurality of cycles have a repetition frequency in the range of 1 kHz to 100 kHz.

8. The plasma processing apparatus according to claim 7, wherein the ON period is less than 50% of one pulse cycle in the sequence of voltage pulses.

9. The plasma processing apparatus according to claim 7, wherein the ON period is less than 20% of one pulse cycle in the sequence of voltage pulses.

10. The plasma processing apparatus according to claim 1, wherein the first voltage level is constant in the plurality of cycles.

11. The plasma processing process according to claim 1, further comprising: an edge ring arranged to surround a substrate on the electrostatic chuck; a ring electrode arranged below the edge ring within the electrostatic chuck; and a second voltage pulse signal generator electrically connected to the ring electrode and configured to generate a second voltage pulse signal, wherein the second voltage pulse signal has a second reference voltage level in the first period and a sequence of second voltage pulses having the second voltage level in the second period, the absolute value of the second voltage level is greater than the absolute value of the second reference voltage level, and each of the plurality of voltage pulses included in the sequence of second voltage pulses has an on period of longer than 0 seconds and of 0.5 microseconds or less.

12. The plasma processing apparatus according to claim 1, wherein the RF signal has a first power level during the first period and a second power level during the second period, the second power level being greater than the first power level.

13. A plasma processing apparatus comprising: a plasma processing chamber; a substrate support portion disposed within the plasma processing chamber; an electrode disposed within the substrate support portion; and a voltage pulse signal generator electrically connected to the electrode and configured to generate a voltage pulse signal, wherein the voltage pulse signal has a sequence of voltage pulses, and each of the plurality of voltage pulses included in the sequence of voltage pulses has an on-period longer than 0 seconds and of 0.5 microseconds or less.

14. The plasma processing apparatus according to claim 13, wherein the ON period is 0.3 μs or less.

15. The plasma processing apparatus according to claim 13 or 14, wherein the sequence of voltage pulses has a first voltage level, and the first voltage level has negative polarity.

16. The plasma processing apparatus according to claim 15, wherein the sequence of voltage pulses has a pulse frequency of 500 kHz or higher.

17. The plasma processing apparatus according to claim 16, wherein the sequence of voltage pulses has a pulse frequency of 2 MHz or less.

18. The plasma processing apparatus according to claim 16, wherein the ON period is less than 50% of one pulse cycle in the sequence of voltage pulses.

19. The plasma apparatus according to claim 16, wherein the ON period is less than 20% of one pulse cycle in the sequence of voltage pulses.

20. The plasma processing apparatus according to claim 13, wherein the first voltage level is constant in the plurality of cycles.

21. The plasma processing process according to claim 13, further comprising: an edge ring arranged to surround a substrate on the substrate support portion; a ring electrode arranged below the edge ring within the substrate support portion; and a second voltage pulse signal generator electrically connected to the ring electrode and configured to generate a second voltage pulse signal, wherein the second voltage pulse signal has a second reference voltage level in the first period and a sequence of second voltage pulses having the second voltage level in the second period, the absolute value of the second voltage level is greater than the absolute value of the second reference voltage level, and each of the plurality of voltage pulses included in the sequence of second voltage pulses has an on period longer than 0 seconds and of 0.5 μm seconds or less.

22. The plasma apparatus according to claim 13, further comprising an RF signal generator configured to generate an RF signal for generating plasma in the chamber, wherein the RF signal has a first power level in the first period and a second power level in the second period, the second power level being greater than the first power level.

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