Plasma processing apparatus and plasma processing method

Abstract

The present invention provides a plasma processing apparatus and a plasma processing method that uses a plurality of high-frequency electric power pulse signals to improve the performance of processing. The plasma processing apparatus has a first RF generating section that generates a first RF pulse signal that has a first power level during a first period, a second power level during a second period, and a third power level during a third period, the first period being 30 μs or less; a second RF generating section that generates a second RF pulse signal that has a frequency lower than that of the first RF pulse signal, a fourth power level during the first period, and a fifth power level during at least one of the second period and the third period; and a third RF generating section that generates a third RF pulse signal that has a frequency lower than that of the second RF pulse signal, a sixth power level during the second period, and a seventh power level during at least one of the first period and the third period.

Description

Technical Field

[0001] This invention relates to plasma processing apparatus and plasma processing method. Background Technology

[0002] For example, Patent Document 1 proposes an ICP (Inductively Coupled Plasma) device having two high-frequency power supplies, supplying high-frequency electrical power at two frequencies to an antenna at the top of the chamber and a lower electrode (base). One of the two high-frequency power supplies supplies high-frequency electrical power for biasing at a frequency of, for example, 13 MHz, to the lower electrode. An antenna is positioned above the chamber, and the other high-frequency power supply supplies high-frequency electrical power for plasma excitation at, for example, 27 MHz, to the midpoint or vicinity of the line forming the outer coil of the antenna.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2019-67503 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This invention provides a technique for improving processing performance by using multiple high-frequency (RF) electrical power pulse signals.

[0008] Technical means for solving problems

[0009] According to one aspect of the present invention, a plasma processing apparatus is provided, comprising: a first matching circuit coupled to a chamber; a second matching circuit coupled to a chamber; a first RF generation unit configured to be coupled to the first matching circuit and capable of generating a first RF pulse signal comprising multiple pulse cycles, the multiple pulse cycles comprising a first period, a second period, and a third period, the first RF pulse signal having a first power level in the first period, a second power level in the second period, and a third power level in the third period, the first period being 30 μs or less; a second RF generation unit configured to be coupled to the second matching circuit and capable of generating a second RF pulse signal comprising multiple pulse cycles, the frequency of the second RF pulse signal being lower than the frequency of the first RF pulse signal, the second RF pulse signal having a fourth power level in the first period, and a fifth power level in at least one of the second and third periods; and a third RF generation unit configured to be coupled to the second matching circuit and capable of generating a third RF pulse signal comprising multiple pulse cycles, the frequency of the third RF pulse signal being lower than the frequency of the second RF pulse signal, the third RF pulse signal having a sixth power level in the second period, and a seventh power level in at least one of the first and third periods.

[0010] Invention Effects

[0011] According to one aspect of the invention, multiple high-frequency electrical power pulse signals can be used to improve processing performance. Attached Figure Description

[0012] Figure 1 This is a cross-sectional schematic diagram illustrating an example of a plasma processing system according to an embodiment.

[0013] Figure 2 This is a diagram illustrating an example of a plasma processing apparatus according to an embodiment.

[0014] Figure 3 This is a diagram illustrating an example of a matching circuit for two biased RF pulse signals in an embodiment.

[0015] Figure 4 This is a diagram illustrating an example of free radicals, ions, electron temperature, ion energy, and byproducts.

[0016] Figure 5 This is a diagram showing the pulse pattern of two high-frequency electrical power pulses of the implementation method.

[0017] Figure 6 This is a diagram showing the pulse patterns of the three frequencies of high-frequency electrical power pulses in the implementation method.

[0018] Explanation of reference numerals in the attached figures

[0019] 1. Plasma processing device

[0020] 2 Control Department

[0021] 10 chambers

[0022] 10s plasma processing space

[0023] 11. Substrate support

[0024] 12 Ring-shaped components

[0025] 13 Gas Inlet Section

[0026] 14 antennas

[0027] 20 Gas Supply Department

[0028] 21 Computer

[0029] 21a Processing Department

[0030] 21b Storage Section

[0031] 21c communication interface

[0032] 31 RF Power Supply Department

[0033] 31a Source RF Generation Unit

[0034] 31b First bias RF generation unit

[0035] 34b1 First Adjustment Circuit

[0036] 34b2 First Separation Circuit

[0037] 34c1 Second Adjustment Circuit

[0038] 34c2 Second Separator Circuit

[0039] 31c Second Bias RF Generation Unit

[0040] 33 First Matching Circuit

[0041] 34 Second Matching Circuit

[0042] 37 Power supply line Detailed Implementation

[0043] Hereinafter, embodiments for carrying out the present invention will be described with reference to the accompanying drawings. In the drawings, the same reference numerals are used to label the same components, and sometimes repeated descriptions are omitted.

[0044] [Plasma Processing System]

[0045] First, refer to Figure 1 and Figure 2The plasma processing system of the embodiment will be described. Figure 1 This is a cross-sectional schematic diagram illustrating an example of a plasma processing system according to an embodiment. Figure 2 This is a diagram illustrating an example of a plasma processing apparatus 1 according to an embodiment.

[0046] In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing apparatus 1 is configured to generate plasma from the processing gas within the chamber 10 by supplying three high-frequency electrical power pulses (three RF pulse signals) into the chamber 10. Alternatively, the plasma processing apparatus 1 can be configured to generate plasma from the processing gas within the chamber 10 by supplying two high-frequency electrical power pulses (two RF pulse signals) into the chamber 10. Furthermore, the plasma processing apparatus 1 processes the substrate by exposing the generated plasma to the substrate.

[0047] The plasma processing apparatus 1 includes a chamber 10, a substrate support 11, and a plasma generation unit. The chamber 10 defines a plasma processing space 10s. Furthermore, the chamber 10 has a gas inlet 10a for supplying at least one processing gas to the plasma processing space 10s, and a gas outlet 10b for discharging gas from the plasma processing space. The gas inlet 10a is connected to at least one gas supply unit 20.

[0048] Gas outlet 10b is, for example, an exhaust port located at the bottom of chamber 10, connected to exhaust system 40. Exhaust system 40 may include a pressure valve and a vacuum pump. The vacuum pump may include a turbomolecular pump, a roughing pump, or a combination thereof.

[0049] The substrate support 11 is disposed within the plasma processing space 10s, supporting the substrate W. The plasma generation unit is configured to generate plasma from at least one processing gas supplied to the plasma processing space 10s. The plasma generated in the plasma processing space 10s can be capacitively coupled plasma (CCP) or inductively coupled plasma (ICP).

[0050] The control unit 2 processes computer-executable commands that cause the plasma processing apparatus 1 to perform the various steps described herein. The control unit 2 can be configured to control the various elements of the plasma processing apparatus 1 to perform the various steps described herein. In embodiments, such as... Figure 1As shown, part or all of the control unit 2 is included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 21. The computer 21 may include, for example, a processing unit (CPU: Central Processing Unit) 21a, a storage unit 21b, and a communication interface 21c. The processing unit 21a may be configured to perform various control actions based on the program stored in the storage unit 21b. The storage unit 21b may also include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 21c may also communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0051] The following will Figure 2 Taking an inductively coupled plasma processing apparatus as an example, the structure of plasma processing apparatus 1 will be further described. Plasma processing apparatus 1 includes a chamber 10. Chamber 10 includes a dielectric window 10c and a sidewall 10d. The dielectric window 10c and sidewall 10d define a plasma processing space 10s within chamber 10. Furthermore, plasma processing apparatus 1 includes a substrate support 11, a gas inlet 13, a gas supply 20, an electrical power supply, and an antenna 14.

[0052] The substrate support 11 is disposed in the plasma processing space 10s within the chamber 10. The antenna 14 is disposed on the upper part or above the chamber 10 (dielectric window 10c).

[0053] The substrate support portion 11 includes a main body and an annular member (edge ​​ring) 12. The main body has a central region (substrate support surface) 11a for supporting a substrate (wafer) W and an annular region (edge ​​ring support surface) 11b for supporting the annular member 12. The annular region 11b of the main body surrounds the central region 11a of the main body. The substrate W is disposed on the central region 11a of the main body, and the annular member 12 is disposed on the annular region 11b of the main body in such a way that it surrounds the substrate W on the central region 11a of the main body. In an embodiment, the main body includes an electrostatic chuck 111 and a conductive member 112. The electrostatic chuck 111 is disposed on the conductive member 112. The conductive member 112 functions as an RF electrode, and the upper surface of the electrostatic chuck 111 functions as the substrate support surface (central region 11a). Furthermore, although not shown in the figure, in an embodiment, the substrate support portion 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 111 and the substrate W to a target temperature. The temperature control module may include a heater, a flow path, or a combination thereof. In the flow path, a temperature-regulating fluid such as a refrigerant or heat transfer gas can flow. Furthermore, the chamber 10, the substrate support 11, and the annular component 12 are configured such that axis Z is aligned with each other when each is centered on axis Z.

[0054] The gas inlet 13 is configured to supply at least one processing gas from the gas supply unit 20 to the plasma processing space 10s. In this embodiment, the gas inlet 13 is disposed above the substrate support 11 and installed in the central opening formed in the dielectric window 10c.

[0055] The gas supply unit 20 may also include at least one gas source 23 and at least one flow controller 22. In an embodiment, the gas supply unit 20 is configured to supply one or more processing gases from their respective gas sources 23 to the gas inlet unit 13 via their respective flow controllers 22. Each flow controller 22 may also include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may also include one or more flow modulation devices for modulating or pulsedizing the flow rate of one or more processing gases.

[0056] The power supply unit includes an RF power supply unit 31 coupled to the chamber 10. The RF power supply unit 31 is configured to supply three RF signals (RF power) to the conductive member 112 or the antenna 14 of the substrate support 11. Thus, plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Alternatively, the plasma generation unit may be configured to include a gas supply unit 20 supplying at least one processing gas to the plasma processing space 10s and an RF power supply unit 31, capable of generating plasma from the processing gas.

[0057] Antenna 14 includes one or more coils. In one embodiment, antenna 14 may also include an outer coil and an inner coil arranged coaxially. In this case, the RF power supply unit 31 may be connected to both the outer coil and the inner coil, or it may be connected to either the outer coil or the inner coil. In the former case, the same RF generating unit may be connected to both the outer coil and the inner coil, or different RF generating units may be connected to the outer coil and the inner coil respectively.

[0058] In this embodiment, the RF power supply unit 31 includes a generation source RF generation unit 31a, a first bias RF generation unit 31b, and a second bias RF generation unit 31c. The generation source RF generation unit 31a is coupled to the antenna 14, and the first bias RF generation unit 31b and the second bias RF generation unit 31c are coupled to the conductive component 112. The generation source RF generation unit 31a is configured to be connected to the antenna 14 via a first matching circuit 33 and is capable of generating a first RF pulse signal (hereinafter referred to as HF power) for plasma generation. In this embodiment, the first RF pulse signal has a frequency in the range of 20MHz to 60MHz. The generated first RF pulse signal is supplied to the antenna 14. The first RF pulse signal includes multiple pulse cycles, each pulse cycle comprising a first period, a second period, and a third period. The first RF pulse signal has a first power level in the first period, a second power level in the second period, and a third power level in the third period, with the first period being 30μs or less. The first RF pulse signal has at least three power levels, each of which is 0 or greater. Therefore, the first RF pulse signal can have high / medium / low power levels, all of which are greater than 0. Furthermore, the first RF pulse signal can also have high / low power levels and a zero power level (Off). The RF generation unit 31a is an example of a first RF generation unit configured to be coupled to the first matching circuit 33 and capable of generating a first RF pulse signal containing multiple pulse cycles.

[0059] Furthermore, the first bias RF generation unit is configured to be connected to the conductive component 112 of the substrate support portion 11 via the second matching circuit 34 and the power supply line 37, and is capable of generating a second RF pulse signal (hereinafter referred to as LF1 power). The generated second RF pulse signal is supplied to the conductive component 112 of the substrate support portion 11. In an embodiment, the second RF pulse signal has a frequency lower than that of the first RF pulse signal. In an embodiment, the second RF pulse signal has a frequency in the range of 1MHz to 15MHz. The second RF pulse signal has a fourth power level in the first period, and a fifth power level in at least one of the second and third periods. Thus, the second RF pulse signal can have high / low power levels, which are greater than 0. In addition, the second RF pulse signal can also have a power level greater than 0 and a zero power level, i.e., have an on / off signal. The first bias RF generation unit is an example of a second RF generation unit configured to be coupled to the second matching circuit 34 and capable of generating a second RF pulse signal containing multiple pulse cycles.

[0060] Furthermore, the second bias RF generation unit is configured to be connected to the conductive component 112 of the substrate support portion 11 via the second matching circuit 34 and the power supply line 37, and is capable of generating a third RF pulse signal (hereinafter referred to as LF2 power). The generated third RF pulse signal is supplied to the conductive component 112 of the substrate support portion 11. In an embodiment, the third RF pulse signal has a frequency lower than that of the second RF pulse signal. In an embodiment, the third RF pulse signal has a frequency in the range of 100kHz to 4MHz. The third RF pulse signal has a sixth power level in the second period, and a seventh power level in at least one of the first and third periods, and the third RF pulse signal has at least two power levels, each of which is 0 or higher. Thus, the third RF pulse signal can have high / low power levels, which are greater than 0. In addition, the third RF pulse signal can have a power level greater than 0 and a zero power level, i.e., an on / off signal. The second bias RF generation unit is an example of a third RF generation unit configured to be coupled to the second matching circuit 34 and capable of generating a third RF pulse signal containing multiple pulse cycles.

[0061] In this way, the first RF pulse signal, the second RF pulse signal, and the third RF pulse signal are pulsed. The second RF pulse signal and the third RF pulse signal are pulsed between an on state and an off state, or between two or more different on states (high / low). The first RF pulse signal is pulsed between two or more different on states (high / low) and an off state, or between three or more different on states (high / medium / low). The first RF pulse signal can be pulsed between an on state and an off state, or between two different on states (high / low).

[0062] The first matching circuit 33 is connected to the RF generation source 31a and the antenna 14, and is connected to the chamber 10 via the antenna 14. The first matching circuit 33 enables a first RF pulse signal to be supplied from the RF generation source 31a to the antenna 14 via the first matching circuit 33. Furthermore, in other plasma processing apparatuses, the first matching circuit 33 can be connected to components other than the antenna 14. For example, in a capacitively coupled plasma processing apparatus containing two opposing electrodes, the first matching circuit 33 can be connected to one of the two electrodes.

[0063] The second matching circuit 34 is connected to the first bias RF generation unit 31b, the second bias RF generation unit 31c, and the substrate support unit 11 (conductive member 112). The second matching circuit 34 enables a second RF pulse signal to be supplied from the first bias RF generation unit 31b to the substrate support unit 11 via the second matching circuit 34. Furthermore, the second matching circuit 34 enables a third RF pulse signal to be supplied from the second bias RF generation unit 31c to the substrate support unit 11 via the second matching circuit 34.

[0064] Control unit 2 outputs control signals to instruct the supply of pulse signals to the generation source RF generation unit 31a, the first bias RF generation unit 31b, and the second bias RF generation unit 31c, respectively. This allows the supply of a first RF pulse signal, a second RF pulse signal, and a third RF pulse signal comprising multiple pulse cycles at predetermined timings, generating plasma from the processing gas within chamber 10. The substrate is then processed by exposing it to the generated plasma. This improves processing efficiency and enables high-precision substrate processing. The timing of the on / off states or power levels above 0 for the first RF pulse signal, the second RF pulse signal, and the third RF pulse signal controlled by control unit 2 will be described later.

[0065] [An example of the internal structure of the second matching circuit]

[0066] Next, refer to Figure 3 An example of the structure of the second matching circuit 34 will be described. Figure 3 This is a diagram illustrating an example of the internal structure of the second matching circuit 34 in the implementation method.

[0067] The first bias RF generator 31b and the second bias RF generator 31c are connected to the substrate support 11 (conductive member 112) via the second matching circuit 34 and the power supply line 37. In the following description, the second RF pulse signal supplied from the first bias RF generator 31b will be referred to as LF1 power. Furthermore, in the following description, the third RF pulse signal supplied from the second bias RF generator 31c will be referred to as LF2 power.

[0068] When the second RF pulse signal (LF1 power) supplied from the first bias RF generation unit 31b is coupled to the opposite side (the side of the second bias RF generation unit 31c) via the power supply line 36 in the second matching circuit 34, the supply efficiency of the LF1 power supplied to the chamber 10 decreases. Similarly, when the third RF pulse signal (LF2 power) supplied from the second bias RF generation unit 31c is coupled to the opposite side (the side of the first bias RF generation unit 31b) via the power supply line 36, the supply efficiency of the LF2 power supplied to the chamber 10 decreases. As a result, due to the decrease in the supply of bias power to the chamber 10, it is difficult to control ion energy, and the processing performance deteriorates.

[0069] Therefore, the second matching circuit 34 of this embodiment includes a first adjustment circuit 34b1, a first separation circuit 34b2, a second adjustment circuit 34c1, and a second separation circuit 34c2. The first adjustment circuit 34b1 and the first separation circuit 34b2 are connected between the first bias RF generation unit 31b and the power supply line 37. The second adjustment circuit 34c1 and the second separation circuit 34c2 are connected between the second bias RF generation unit 31c and the power supply line 37. According to this structure, the second RF pulse signal (LF1 power) generated by the first bias RF generation unit 31b is supplied to the substrate support unit 11 (conductive member 112) while its coupling with the second bias RF generation unit 31c is suppressed. Furthermore, the third RF pulse signal (LF2 power) generated by the second bias RF generation unit 31c is supplied to the substrate support unit 11 (conductive member 112) while its coupling with the first bias RF generation unit 31b is suppressed.

[0070] The first adjustment circuit 34b1 has a variable element configured to match the impedance of the load side (substrate support 11 side) of the first bias RF generation unit 31b with the output impedance of the first bias RF generation unit 31b. In one embodiment, the variable element of the first adjustment circuit 34b1 is a variable capacitor.

[0071] The second separation circuit 34c2 is connected between the second bias RF generation unit 31c and the substrate support unit 11 to prevent the coupling of the second RF pulse signal, which is the electrical power of LF1, from the first bias RF generation unit 31b.

[0072] The second adjustment circuit 34c1 has a variable element configured to match the impedance of the load side (substrate support 11 side) of the second bias RF generation unit 31c with the output impedance of the second bias RF generation unit 31c. In one embodiment, the variable element of the second adjustment circuit 34c1 is a variable inductor.

[0073] The first separation circuit 34b2 is connected between the first bias RF generation unit 31b and the substrate support unit 11 to prevent the coupling of the third RF pulse signal, which is the electrical power of LF2, from the second bias RF generation unit 31c.

[0074] The second separation circuit 34c2 is an RF choke circuit containing inductor L2. The first separation circuit 34b2 is a resonant circuit containing capacitor C1 and inductor L1. The first separation circuit 34b2 is composed of capacitor C1 and inductor L1. The second separation circuit 34c2 is composed of inductor L2.

[0075] The first separation circuit 34b2 sets the circuit constants of C1 and L1 such that its impedance is 0 or close to 0 when viewed from the second RF pulse signal, and high when viewed from the third RF pulse signal, treating the side of the first bias RF generation unit 31b as a wall. Therefore, the impedance in the first separation circuit 34b2 when viewed from the third RF pulse signal is denoted as Z. LF2 Let the load impedance of the plasma be denoted as Z. chamber At that time, Z LF2 >>Z chamber .

[0076] Furthermore, the second separation circuit 34c2 sets the circuit constant of L2 such that its impedance is 0 or close to 0 when viewed from the third RF pulse signal, and its impedance is high when viewed from the second RF pulse signal, treating the side of the second bias RF generation unit 31c as a wall. Therefore, the impedance in the second separation circuit 34c2 when viewed from the second RF pulse signal is denoted as Z. LF1 At that time, Z LF1 >>Z chamber Established.

[0077] In this way, by setting the circuit constants of the first separation circuit 34b2 as described above, the impedance Z in the first separation circuit 34b2 is... LF2 Much greater than the load impedance Z of the plasma chamber Therefore, the first separation circuit 34b2 prevents the coupling of the third RF pulse signal from the second bias RF generation unit 31c. Figure 3 (LF2 power → ×). As a result, LF2 power is supplied to chamber 10 via power supply line 37, thereby suppressing the reduction in the supply efficiency of LF2 power.

[0078] Similarly, by setting the circuit constants of the second separation circuit 34c2 as described above, the impedance Z in the second separation circuit 34c2 is... LF1 Much greater than the load impedance Z of the plasma chamber Therefore, the second separation circuit 34c2 prevents the coupling of the second RF pulse signal from the first bias RF generation unit 31b. Figure 3 (LF1 power → ×). As a result, LF1 power is supplied to chamber 10 via power supply line 37, thereby suppressing the reduction in the supply efficiency of LF1 power.

[0079] Using this structure, pulse signals with two bias electrical powers (LF1 power and LF2 power) with different frequencies can be efficiently supplied to the substrate support 11.

[0080] [Pulse signal]

[0081] For example, when etching deep holes with high aspect ratios, pulse signals of HF, LF1, and LF2 power can be used to make the ion incident angle perpendicular or to improve the mask selectivity.

[0082] Figure 4 This is a diagram illustrating an example of free radicals, ions, electron temperature, ion energy, and byproducts. Figure 4 The horizontal axis represents the elapsed time (1 cycle) after the RF power supply is stopped (turned off). Figure 4 The vertical axis represents the state of radicals, ions, electron temperature (Te), ion energy (ε1), and by-products at each time point during the turn-off time.

[0083] Accordingly, the change in radicals is slow after the RF power is turned off, whereas the changes in ions and plasma temperature (Te) are faster. Considering the decay of radicals and ions, energy changes, etc., in such a plasma, pulse signals are used to control the HF and LF power (e.g., LF1 and LF2 power). As an example of a pulse signal for supplying LF power after turning off the HF power, consider controlling the LF power to be turned off initially when the plasma temperature (Te) is high, and then turned on after the plasma temperature (Te) decreases. Therefore, although ions may remain, using LF power at the low plasma temperature (Te) allows for efficient ion introduction into the substrate.

[0084] As another example of a pulse signal for the LF power supplied after the HF power is turned off, the LF2 power is controlled while the plasma electron temperature Te remains almost unchanged, using ε1, which represents the ion energy, as a plasma parameter. Thus, the ion energy ε1 can be controlled to make the ion incident angle more perpendicular.

[0085] In this way, by meticulously controlling the timing of turning the HF and LF power on / off states based on variations in plasma parameters such as free radicals, ions, plasma electron temperature, ion energy, and byproducts, the processing performance can be improved. The timing of supplying the high-frequency power pulse signal will be discussed below. Figures 5-6 This will be explained. Furthermore, the timing of the supply of the high-frequency electrical power pulse signal is controlled by the control unit 2.

[0086] (Pulse signals at two frequencies)

[0087] Figure 5 This is a diagram showing the pulse patterns of two high-frequency electrical power pulses at different frequencies in the embodiment. As... Figure 5 The high-frequency power pulses shown, specifically the HF power (source power) and LF1 power (bias power) pulse signals, each contain multiple pulse cycles. The timing of each pulse signal supply is explained below. Figure 5 The horizontal axis represents the time of one cycle, and the vertical axis represents the on / off state of HF power and LF1 power. Taking period (1) and period (2) as one cycle, the control of each pulse signal of HF power and LF1 power is repeated.

[0088] In the control of high-frequency electrical power pulses at two frequencies, the on-state of HF electrical power and the on-state of LF1 electrical power overlap in time. During the period when HF electrical power is on, LF1 electrical power is on; during the period when HF electrical power is off, LF1 electrical power is off. The RF generation unit 31a is configured to generate a first RF pulse signal (HF electrical power). In this embodiment, the first RF pulse signal has two power levels (On / Off). For example, the first RF pulse signal may have a frequency of 27MHz.

[0089] The first bias RF generation unit 31b is configured to generate a second RF pulse signal (LF1 power). In this embodiment, the second RF pulse signal has two power levels (On / Off). The frequency of the second RF pulse signal is lower than the frequency of the first RF pulse signal. For example, the second RF pulse signal has a frequency of 13MHz.

[0090] Figure 5 During the period (1), the HF power and LF1 power remain in the on state. That is, at time t0, the HF power and LF1 power switch to the on state, and at time t1, the HF power and LF1 power switch to the off state. Thus, during the time from time t0 to time t1, by supplying the HF power, a plasma containing free radicals and ions is generated, and by supplying the LF1 power, the ion flow (ion quantity) reaching the bottom of the etched recess is controlled, thereby promoting etching.

[0091] At time t1 after period (1), the HF power and LF1 power transition to the off state. During period (2), the HF power and LF1 power remain in the off state. During period (2), the HF power is in the off state, therefore... Figure 4 As illustrated in the example, the free radicals, ions, and plasma temperatures decay based on time constants. Furthermore, during period (2), the HF and LF1 electrical powers are off, thus the byproducts are degassed. Period (2), representing the degassing period, is preset to a time during which byproducts do not adhere to the substrate W.

[0092] At time t2 after the exhaust period, the system returns from period (2) to period (1), and at time t0, the HF and LF1 power supplies are switched on again. Then, the control of each pulse signal of the HF and LF1 power supplies is repeated, with period (1) and period (2) as one cycle. One cycle is 10kHz to 20kHz. Multiple pulse cycles have the same time period, and each pulse cycle has a time period of 50μs to 100μs. That is, one cycle of the pulse cycle is 50μs to 100μs.

[0093] In this example, the first bias RF generation unit 31b is configured to synchronize the change time of the power level of the second RF pulse signal with the change time of the power level of the first RF pulse signal.

[0094] Furthermore, period (1) is set to 30 μs or less. The next period (2) is set to any time, which can be longer than 30 μs. That is, in this example, the HF power and LF1 power are kept on for a time of 30 μs or less during period (1), and kept off for any time during period (2), and the on / off state is repeated. By making the supply time of LF1 power in one cycle less than 30 μs in this way, the ions can be controlled vertically to perform highly anisotropic etching.

[0095] Furthermore, the HF power level during period (1) is an example of the first power level, and the HF power level during period (2) is an example of the second power level. The LF1 power level during period (1) is an example of the third power level, and the LF1 power level during period (2) is an example of the fourth power level.

[0096] (Pulse signals at 3 frequencies)

[0097] Figure 6 This is a diagram showing the pulse patterns of high-frequency electrical power pulses at three frequencies according to the implementation method. First, as... Figure 6 The pulse signals of the three high-frequency electrical powers shown—HF power (Source Power), LF1 power (Bias1 Power), and LF2 power (Bias2 Power)—each contain multiple pulse cycles. The timing of each pulse signal supply is explained below. Figure 6 The horizontal axis represents the time of one cycle, and the vertical axis represents the on / off state of HF power, LF1 power and LF2 power. The control of each pulse signal of HF power, LF1 power and LF2 power is repeated with the period (1) to (3) as one cycle.

[0098] In the control of three high-frequency power pulses, the on-states of LF1 and LF2 do not overlap in time. During the period when LF1 is on, LF2 is off, and vice versa. The on-states of HF and LF1, and HF and LF2, may or may not overlap in time.

[0099] The RF generation unit 31a is configured to generate a first RF pulse signal (HF electrical power). In this embodiment, the first RF pulse signal has three power levels (high / low / none). These power levels can be arbitrarily set and changed according to the target processing. For example, the first RF pulse signal has a frequency of 27MHz.

[0100] The first bias RF generation unit 31b is configured to generate a second RF pulse signal (LF1 power). In this embodiment, the second RF pulse signal has two power levels (On / Off). That is, the second RF pulse signal has two or more power levels, including a zero power level. The frequency of the second RF pulse signal is lower than the frequency of the first RF pulse signal. For example, the second RF pulse signal has a frequency of 13MHz.

[0101] The second bias RF generation unit 31c is configured to generate a third RF pulse signal (LF2 electrical power). In this embodiment, the third RF pulse signal has two power levels (On / Off). That is, the third RF pulse signal has two or more power levels, including a zero power level. The frequency of the third RF pulse signal is lower than the frequency of the second RF pulse signal. For example, the third RF pulse signal has a frequency of 1.2 MHz.

[0102] Figure 6 In this context, the source power (HF power) represents the state of the first RF pulse signal, the first bias power (LF1 power) represents the state of the second RF pulse signal, and the second bias power (LF2 power) represents the state of the third RF pulse signal.

[0103] Figure 6 During period (1), the HF power has a high power level, the LF1 power is on, and the LF2 power is off. That is, from time t0 to time t... 11 Time T s In this process, plasma containing free radicals and ions is generated by supplying HF electric power. Furthermore, from time t0 to time t... 11 During the etching process, the ion flow (ion quantity) reaching the bottom of the etched recess can be controlled by the supply of electrical power from LF1, thus promoting etching. Therefore, as... Figure 6 As shown in (a), the target film 100 is etched via mask 101, and free radicals R are mainly attached to the inner wall of the holes HL formed in the etched target film 100. In addition, ions are controlled to control the ion flow reaching the bottom of the etched recess.

[0104] Furthermore, period (1) is set to a time of 30 μs or less. In addition, the subsequent periods (2) and (3) are set to any time, which can be longer than 30 μs. That is, in this example, the HF power and LF1 power are kept on for a time of 30 μs or less during period (1). By supplying LF1 power for a short time of 30 μs or less during period (1) in this way, it is possible to further control the ions to be vertical and perform highly anisotropic etching.

[0105] After period (1), at time t 11 The HF power level shifts from high power level to low power level (or off state), the LF1 power level shifts to off state, and the LF2 power level shifts to on state. Thus, as... Figure 4As shown in the example, the free radicals, ions, and plasma temperature decay with their respective time constants. Based on the decay state of these plasma parameters, the LF2 power is turned on during the period (2) when the power level of the HF power is controlled to decrease or be turned off, and during the period (3) when the byproducts are vented.

[0106] In this embodiment, during period (2), the HF power is maintained at a low power level, the LF1 power is maintained in the off state, and the LF2 power is maintained in the on state. During period (2), the LF2 power is supplied at a frequency lower than that of the LF1 power supplied during period (1). The Vpp of the LF2 power is greater than that of the LF1 power. Therefore, during period (2), compared to period (1), the bias voltage Vpp can be made larger, the ion energy εl can be made larger, and the ion incident angle can be controlled more vertically. Therefore, during period (2), the ion flow reaching the bottom of the etched recess can be controlled, such as... Figure 6 As shown in (b), byproducts such as B remaining at the bottom corner of hole HL are etched, which can promote etching.

[0107] At time t 12 The HF power is switched off (or at a low power level), the LF1 power remains off, and the LF2 power is switched off. During this period (3), the exhaust of byproducts is controlled. That is, during this period (3), the HF power, LF1 power, and LF2 power remain off. Thus, as Figure 6 As shown in (c), the byproduct B attached to the hole HL is vented. This facilitates etching in the next cycle. Period (3) is preset to a time during which byproduct B will not reattach to the substrate W.

[0108] At time t 13 During period (1), the HF power is switched to a high power level, the LF1 power is switched to the on state, and the LF2 power remains in the off state. The processing is repeated between periods (1) and (3), with one cycle being 10kHz to 20kHz and period (1) being less than 30μs. The multiple pulse cycles are 50μs to 100μs respectively.

[0109] In this way, when etching deep holes with high aspect ratios, using pulsed signals of HF, LF1, and LF2 power can improve mask selectivity and make the ion incident angle perpendicular. This allows for a more perpendicular etched shape or promotes etching. However, etching deep holes with high aspect ratios is just one example of substrate processing; the types of processing are not limited to this.

[0110] Figure 6In the example, the power level of HF is controlled to three power levels, and the power levels of LF1 and LF2 are controlled to two power levels in the on / off state, but this is not a limitation. For example, the power level of HF can also be controlled to four or more power levels.

[0111] Furthermore, the HF power level during period (1) is an example of the first power level, the HF power level during period (2) is an example of the second power level, and the HF power level during period (3) is an example of the third power level. The LF1 power level during period (1) is an example of the fourth power level, and the LF1 power level during periods (2) and / or (3) is an example of the fifth power level. The LF2 power level during period (2) is an example of the sixth power level, and the LF1 power level during periods (1) and / or (3) is an example of the seventh power level.

[0112] As explained above, the plasma processing apparatus and plasma processing method according to this embodiment can use multiple high-frequency electrical power pulse signals to improve processing performance.

[0113] All aspects of the plasma processing apparatus and plasma processing method disclosed herein are illustrative and not limiting. Various modifications and improvements can be made to the embodiments without departing from their essence. The items described in the above embodiments can also be implemented by other structures without contradiction, and furthermore, can be combined without contradiction.

Claims

1. A plasma processing device, characterized in that, have: chamber; A first matching circuit coupled to the chamber; A second matching circuit coupled to the chamber; The first RF generation unit is configured to be coupled to the first matching circuit and is capable of generating a first RF pulse signal. The first RF pulse signal has a first power level greater than zero in a first period within each cycle, a second power level smaller than the first power level but greater than zero in a second period after the first period within each cycle, and a zero power level in a third period after the second period within each cycle. The first period is 30 μs or less. The second RF generation unit is configured to be coupled to the second matching circuit and is capable of generating a second RF pulse signal. The frequency of the second RF pulse signal is lower than the frequency of the first RF pulse signal. The second RF pulse signal has a third power level greater than zero during the first period and a zero power level during the second period and the third period. and The third RF generation unit is configured to be coupled to the second matching circuit and is capable of generating a third RF pulse signal. The frequency of the third RF pulse signal is lower than the frequency of the second RF pulse signal. The third RF pulse signal has a fourth power level greater than zero during the second period and a zero power level during the first period and the third period.

2. The plasma processing apparatus as described in claim 1, characterized in that: Each period has a duration of 50μs to 100μs.

3. The plasma processing apparatus as described in claim 1 or 2, characterized in that: The first RF pulse signal has a frequency of 20MHz to 60MHz. The second RF pulse signal has a frequency of 1MHz to 15MHz. The third RF pulse signal has a frequency of 100kHz to 4MHz.

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