Plasma processing apparatus and plasma processing method

Abstract

To improve a process performance.SOLUTION: A plasma processing apparatus comprises: a first electrode that supports a substrate; a second electrode or an antenna opposed to the first electrode; a first high-frequency power supply unit that supplies a first high-frequency power pulse for plasma generation to the first electrode, the second electrode, or the antenna; a second high-frequency power supply unit that supplies a second high-frequency power pulse for bias to the first electrode; and a control unit. The control unit performs control to provide an interval period to any one of the first and second high-frequency power pulses, to set at least one of pulse cycles of the first and second high-frequency power pulses to five or more times the cycle of the interval period, to output the first and second high-frequency power pulses with duty ratios of 90% or less, and to process a processed substrate with plasma generated from a process gas in response to the output of the first and second high-frequency power pulses.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a plasma processing apparatus and a plasma processing method. [Background technology]

[0002] Patent Document 1 proposes a plasma processing method in which a pulse wave of high frequency power for plasma generation and a pulse wave of high frequency power for biasing, which has a lower frequency than the frequency of the high frequency power for plasma generation, are applied to a mounting table. In this plasma processing method, the pulse wave of high frequency power for plasma generation and the pulse wave of high frequency power for biasing have a phase difference, and the duty ratio of the high frequency power for plasma generation is controlled to be equal to or greater than the duty ratio of the high frequency power for biasing. This provides an offset between the pulse wave of high frequency power for plasma generation and the pulse wave of high frequency power for biasing. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2016-157735 A Summary of the Invention [Problem to be solved by the invention]

[0004] To reduce or improve bowing of etched recesses, CD size variations, mask distortion and blockage, etc., it is important to precisely control radicals, ion density, ion incidence angle, sidewall protection, etc.

[0005] The present disclosure provides techniques that can improve the performance of processes carried out in a plasma processing apparatus. [Means for solving the problem]

[0006] According to one aspect of the present disclosure, there is provided a process chamber capable of being evacuated to a vacuum, The aboveA first electrode is disposed in a processing vessel and supports a substrate to be processed. A second electrode or an antenna is provided opposite to the first electrode. A plasma generating element is connected to the first electrode, the second electrode, or the antenna. Consecutive multiple a first high frequency power supply unit that supplies a first high frequency power pulse; synchronized with the first radio frequency power pulse, For bias Consecutive multiple a second high frequency power supply unit that supplies a second high frequency power pulse; and and A control unit that controls the second high frequency power supply unit, In an etching process for an etching target film of one processing object, providing an interval period for either the first high frequency power pulse or the second high frequency power pulse; and the interval period is not provided for the other of the first high frequency power pulse or the second high frequency power pulse, The first high frequency power pulse No. 1 Pulse frequency and the second high frequency power pulse Second Pulse Frequency The interval period Repetition rate a duty ratio of the first high frequency power pulse and the second high frequency power pulse is set to 90% or less, and a plasma is generated from a processing gas supplied into the processing chamber in response to the output of the first high frequency power pulse and the second high frequency power pulse. The above A plasma processing apparatus is provided that controls to process a substrate to be processed. Effect of the Invention

[0007] According to one aspect, it is possible to improve the performance of a process carried out in a plasma processing apparatus. [Brief description of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a plasma processing system according to an embodiment. [Diagram 2] FIG. 1 is a diagram showing an example of a conventional plasma processing method. [Diagram 3] 1A to 1C are diagrams showing an example of a plasma processing method according to an embodiment; [Figure 4] 1A to 1C are diagrams for explaining a plasma processing method according to an embodiment; [Diagram 5] 10A to 10C are diagrams showing an example of a plasma processing method according to Modification 1. [Figure 6] 11A to 11C are diagrams showing an example of a plasma processing method according to Modification 2. [Figure 7] 13A to 13C are diagrams for explaining a plasma processing method according to Modification 3. [Figure 8] 13A to 13C are diagrams for explaining a plasma processing method according to Modification 4. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and duplicated descriptions may be omitted.

[0010] [Plasma processing system] An example of the configuration of a plasma processing system will be described below. The plasma processing system includes a capacitively coupled plasma processing device 1 and a control unit 2. The plasma processing device 1 includes a plasma processing chamber 10 that can be evacuated, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing device 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 disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support unit 11. In the embodiment, the shower head 13 constitutes at least a part of the ceiling of the plasma processing chamber 10. The inside of the plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port 13a for supplying at least one processing gas to the plasma processing space 10s and at least one gas exhaust port 10e for exhausting gas from the plasma processing space. The sidewall 10a is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0011] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region (substrate support surface) 111a for supporting a substrate W, for example a wafer, and an annular region (ring support surface) 111b for supporting the ring assembly 112. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. In the embodiment, the main body 111 includes a base and an electrostatic chuck. The base includes a conductive member. The conductive member of the base functions as a lower electrode. The electrostatic chuck is disposed on the base. The upper surface of the electrostatic chuck has a substrate support surface 111a. The ring assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring. Although not shown, the substrate support 11 may include a temperature adjustment module configured to adjust at least one of the electrostatic chuck, the ring assembly 112, and the substrate W to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

[0012] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes a conductive member. The conductive member of the shower head 13 functions as an upper electrode. In addition to the shower head 13, the gas introduction unit may include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0013] The gas supply 20 may include at least one gas source 21 and at least one flow controller 22. In an embodiment, the gas supply 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply 20 may include one or more flow modulation devices to modulate or pulse a flow rate of the at least one process gas.

[0014] The power source 30 includes an RF power source 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power source 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to a conductive member of the substrate support 11 and / or a conductive member of the showerhead 13. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power source 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more processing gases in the plasma processing chamber 10. In addition, by supplying a bias RF signal to the conductive member of the substrate support 11, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.

[0015] In the embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to the conductive member of the substrate support 11 or the conductive member of the shower head 13 via at least one impedance matching circuit, and is configured to generate a source RF signal (source RF power) for plasma generation. In the embodiment, the source RF signal has a frequency in the range of 13 MHz to 150 MHz. In the embodiment, the first RF generating 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 the conductive member of the substrate support 11 or the conductive member of the shower head 13. The second RF generating unit 31b is coupled to the conductive member of the substrate support 11 via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). In the embodiment, the bias RF signal has a lower frequency than the source RF signal. In the embodiment, the bias RF signal has a frequency in the range of 400 KHz to 13.56 MHz. In embodiments, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated bias RF signal or signals are provided to the conductive members of the substrate support 11. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0016] The conductive member of the base of the substrate support 11 provided in the plasma processing chamber 10 is an example of a first electrode disposed in the processing vessel and supporting the substrate to be processed. The conductive member of the shower head 13 is an example of a second electrode provided opposite the first electrode. An antenna may be provided opposite the first electrode instead of the shower head 13, which is an example of the second electrode. The plasma processing system may include an inductively coupled plasma processing apparatus instead of the capacitively coupled plasma processing apparatus 1. In the inductively coupled plasma processing apparatus, an antenna may be provided on the upper part of the plasma processing chamber 10 opposite the first electrode supporting the substrate to be processed, and the first RF generating unit 31a may be connected to the antenna.

[0017] The first RF generating unit 31a may be connected to the first electrode, the second electrode, or the antenna. The first RF generating unit 31a is an example of a first high frequency power supplying unit that supplies a first high frequency power pulse (hereinafter also referred to as an "HF pulse"), which is a pulse wave of a first high frequency power for generating plasma, to the first electrode, the second electrode, or the antenna. The second RF generating unit 31b is an example of a second high frequency power supplying unit that is connected to the first electrode and supplies a second high frequency power pulse (hereinafter also referred to as an "LF pulse"), which is a pulse wave of a second high frequency power for biasing, to the first electrode.

[0018] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In an embodiment, the first DC generator 32a is connected to a conductive member of the substrate support 11 and configured to generate a first DC signal. The generated first bias DC signal is applied to the conductive member of the substrate support 11. In an embodiment, the first DC signal may be applied to another electrode, such as an electrode in an electrostatic chuck. In an embodiment, the second DC generator 32b is connected to a conductive member of the showerhead 13 and configured to generate a second DC signal. The generated second DC signal is applied to the conductive member of the showerhead 13. In various embodiments, at least one of the first and second DC signals may be pulsed. The first DC generator 32a and the second DC generator 32b are provided in addition to the RF power supply 31.

[0019] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0020] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to execute various steps described in the present disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to execute various steps described herein. For example, the control unit 2 controls the first RF generating unit 31a and the second RF generating unit 31b. In the embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations based on a program stored in the storage unit 2a2. The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0021] Next, an example of a conventional plasma processing method will be described with reference to FIG. 2, and then a plasma processing method according to an embodiment will be described with reference to FIGS. 3 and 4. The plasma processing method according to the embodiment is controlled by a control unit 2. The source RF signal supplied from the first RF generating unit 31a is also referred to as a first high frequency power or HF. The pulse wave of the first high frequency power is also referred to as an HF pulse. The bias RF signal supplied from the second RF generating unit 31b is also referred to as a second high frequency power or LF. The pulse wave of the second high frequency power is also referred to as an LF pulse.

[0022] [Conventional plasma processing method] FIG. 2 is a diagram showing an example of a conventional plasma processing method. In the conventional plasma processing method, the HF and LF are pulse waves. The duty ratio of the HF pulse is 40%. The duty ratio of the LF pulse is 25%. In the example of FIG. 2, the phases of the HF and LF are shifted by 40% based on the time when the HF is turned on, and the on-times (supply time, application time) of the HF and LF do not overlap. The LF is turned on when the HF is turned off (supply is stopped). The HF is turned on for 40% of one cycle, the LF is turned on for 25%, and the HF and LF are turned off for 35%, totaling 100%.

[0023] While the HF is on, plasma and radicals are generated. While the LF is on, ions in the plasma are attracted to the substrate, accelerating the etching. While the HF and LF are off, by-products (reaction products) generated during etching are exhausted from the recesses formed in the object to be etched.

[0024] In order to achieve high anisotropic etching, i.e., verticality of the etching profile, while maintaining a high etching rate, high-output LF power is required. However, in the example of FIG. 2, while the LF is on, high-output LF power is applied, and while the etching target film on the substrate is etched by high-energy ions, the mask is also scraped by the etching of the high-energy ions. In addition, a large amount of by-products adhere to the mask as the etching is accelerated by the high-energy ions. This causes clogging of the mask on the etching target film. Mask clogging refers to the narrowing of the opening of the mask or the complete blocking of the opening of the mask due to the by-products adhering to the side walls of the mask. One method of avoiding mask clogging is to turn off both the HF and LF and provide a time (Off Time) to promote exhaust. However, if the LF is turned off for a short time, the by-products are not efficiently exhausted from the recesses of the etching target.

[0025] Therefore, in the plasma processing method according to the embodiment described below, the on and off times of the HF and LF pulses are controlled, and the on and off times of the LF are set at a lower frequency, thereby making it possible to avoid mask clogging.

[0026] [Plasma Processing Method According to the Embodiment] A plasma processing method according to an embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 is a diagram illustrating an example of the plasma processing method according to an embodiment. Fig. 4 is a diagram for explaining the plasma processing method according to an embodiment.

[0027] In the plasma processing method according to the embodiment, as shown in FIG. 3, the HF pulse frequency F 1st place and LF pulse frequency F 2 The frequency of the HF pulse represented by the pulse frequency F1 and the frequency of the LF pulse represented by the pulse frequency F2 are set to control the on and off cycle. frequency is 1 KHz in the example of FIG. 3. The duty ratio of the HF pulse (Duty1) and the duty ratio of the LF pulse (Duty2) are 50%. The HF and LF are synchronized, and the on and off timings of the HF and LF are the same in the first and second cycles. Duty1 indicates the on time of the HF relative to the total on and off times of the HF. Duty2 indicates the on time of the LF relative to the total on and off times of the LF. The on and off times of the HF and LF are synchronized in the first and second cycles. However, the phases of the HF and LF may be shifted.

[0028] The LF pulse is turned off between the third cycle and the tenth cycle. The time during which the LF pulse is turned off is also called the interval period. repetition frequency F 3 is , LF pulse interval period (LF pulse interval period) Repetition frequency Interval period Repetition frequency is repetition The frequency F3 is Pulse Frequency F1 and Pulse This is lower than frequency F2. In the example in Figure 3, Pulse Frequency F1 and Pulse Frequency F2 is repetition This is 10 times the frequency F3. repetition Interval period of LF pulses indicated by frequency F3 Repetition frequency is 0.1 KHz in the example of Fig. 3. Duty3 indicates the time for repeating the on / off cycle of the LF pulse indicated by Duty2 relative to the total time of the LF off time (total time of 1st and 2nd cycles in Fig. 3) and the total time of the LF off time (total time of 3rd to 10th cycles in Fig. 3). The ratio of the HF on time to one cycle time is set to Duty1 so that the total time of the HF on time and off time does not exceed one cycle time.

[0029] In the example of Fig. 3, the interval period during which the LF is continuously in the OFF state is set to 80% of the total time of the repeating on / off cycle of the LF pulse indicated by Duty 2 (total cycle time of 1 cycle and 2 cycles) and the LF interval period. Duty 3 is set to 20% of the total time of the repeating on / off cycle of the LF pulse indicated by Duty 2 (total cycle time of 1 cycle and 2 cycles) and the interval period during which the LF is continuously in the OFF state.

[0030] When Duty3 is 20%, the on / off cycle of the LF pulse is repeated twice while the on / off cycle of the HF pulse is repeated 10 times. During the first and second cycles, the on / off of the HF pulse and the LF pulse is repeated periodically. During the third to tenth cycles, the on / off of the HF pulse is repeated periodically as in the first and second cycles, but the LF is controlled to be off. In the example of FIG. 3, the LF pulse is synchronized with the HF pulse in the first and second cycles, but this is not limiting, and the LF pulse may be synchronized with the HF pulse from the third cycle onwards.

[0031] The control unit 2 controls the substrate W to be processed by plasma generated from the processing gas supplied into the plasma processing chamber 10 according to the output of the HF pulse and the LF pulse. By providing an interval period during which only the LF is turned off, it is possible to avoid mask clogging. The reason for this will be described with reference to FIG.

[0032] In this embodiment, for example, a SiO2 film is formed as the etching target film 101, and a mask 102 such as an organic film is formed thereon. However, the film structure on the substrate W is not limited to this.

[0033] In the period A of the first cycle shown in Fig. 4, the HF pulse and the LF pulse are controlled to be ON. Thus, as shown in the upper part of Fig. 4(a), the HF contributes to the generation of plasma and radicals, and ions, electrons, and radicals are generated. Also, as shown in the lower part of Fig. 4(a), the LF draws high-energy ions into the recesses of the film 101 to be etched. As a result, in the period A, etching is mainly promoted by the ions with high energy. The ion energy is high, the etching rate is fast, and the ion incidence angle is relatively narrow, so etching tends to proceed vertically, but damage to the mask 102 is large.

[0034] In period B of the first cycle, the HF pulse and the LF pulse are controlled to be off. Therefore, in period B, the plasma and radicals generated in period A decay, and as shown in the upper part of Fig. 4(b), by-products (reaction products) generated during etching in period A are discharged from the recesses of the film 101 to be etched, facilitating exhaust. Also, as shown in the lower part of Fig. 4(b), ions having weaker energy than those in period A etch the top and sides of the mask 102, thereby removing the by-products attached to the sides of the mask.

[0035] In the periods A and B of the second cycle, the same operations as in the first cycle are repeated, with etching being mainly promoted in the period A and exhaust being mainly promoted in the period B.

[0036] During the third to tenth cycles, the LF pulse is turned off, and only the HF pulse is repeatedly turned on and off at a duty ratio of 50% set to Duty1, similar to the first and second cycles.

[0037] In the third cycle, during period C, HF is controlled to be ON and LF is controlled to be OFF. Therefore, as shown in the upper part of FIG. 4(c), plasma and radicals are generated by HF. Also, since there is no attraction of ions by LF, exhaust of by-products from the recesses of the film 101 to be etched is promoted, as shown in the lower part of FIG. 4(c).

[0038] In period D of the third cycle, the HF pulse and the LF pulse are turned off. Therefore, the plasma and radicals are attenuated and there is no attraction of ions by the LF, so that exhaust of by-products from the recesses of the film 101 to be etched is further promoted as shown in the upper part of FIG. 4(d). In the third to tenth cycles, the reductions of (c) and (d) are repeated, so that exhaust of by-products from the recesses of the film 101 to be etched can be actively performed. In this way, by providing an interval period in which the LF is turned off, mask clogging can be avoided and throughput can be improved.

[0039] [Variations] (Variation 1) Next, Modification 1 in which an interval period is provided in the HF pulse will be described with reference to Fig. 5. Fig. 5 is a diagram showing an example of a plasma processing method according to Modification 1. In Modification 1, the HF pulse is turned off between the 8th and 10th cycles, which is the interval period of the HF pulse. Also, in Modification 1, no interval period is provided in the LF pulse.

[0040] A pulse of an HF pulse indicated by a pulse frequency F1 and a pulse of an LF pulse indicated by a pulse frequency F2 frequencyis 1 KHz in Modification 1. The duty ratio of the HF pulse (Duty 1) is 50%, and the duty ratio of the LF pulse (Duty 2) is 25%. HF and LF are synchronized, and the on timing of HF and LF is the same in the 1st to 7th cycles, and the off timing of LF is earlier than that of HF. However, there may be a phase difference between HF and LF.

[0041] Interval Period Repetition frequency is repetition The frequency F3 is Pulse Frequency F1 and Pulse Lower than frequency F2. Pulse Frequency F1 and Pulse Frequency F2 is repetition It is 10 times the frequency F3. In the first modification, the interval period during which the HF is continuously in the off state is set to 30% of the total time of the repeating on / off cycle of the HF pulse indicated by Duty1 (total cycle time of 1 cycle to 7 cycles) and the HF interval period. Duty3 is set to 70% of the total time of the repeating on and off cycle of the HF pulse indicated by Duty1 (total cycle time of 1 cycle to 7 cycles) and the interval period during which the HF is continuously in the off state.

[0042] When Duty3 is 70%, the on / off cycle of the LF pulse is repeated 10 times while the on / off cycle of the HF pulse is repeated 7 times. During the 1st to 7th cycles, the on / off of the HF pulse and the LF pulse is repeated periodically. During the 8th to 10th cycles, the on / off of the LF pulse is repeated periodically, but the HF is controlled to be off. In the first modification, an example is shown in which the LF pulse is synchronized with the HF pulse during the 1st to 7th cycles, but this is not limiting.

[0043] In the case of the modified example 1, the operations (a) and (b) shown in the A period and the B period of FIG. 4 are repeated in the 1st to 7th cycles. However, in the modified example 1, the LF on time is shorter than that in the embodiment, so the degree of attraction of high-energy ions is smaller, and the etching rate is lower, but the damage to the mask is less. In the interval period from the 8th to the 10th cycles, the LF pulse is repeatedly turned on and off, and the HF pulse is controlled to be off. As a result, the collision between the reaction product and the ions during etching is suppressed, and the mask selectivity is improved. In addition, in the HF interval period from the 8th to the 10th cycles, the electron density in the plasma is reduced, so the incident angle of the ions is relatively narrow, and etching tends to proceed vertically. The above is the effect of the modified example 1 in which an interval period is provided in the HF pulse.

[0044] (Variation 2) Next, a second modification in which an interval period is provided between the HF pulse and the LF pulse will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of a plasma processing method according to the second modification.

[0045] In Modification 2, an interval period is provided for both the HF pulse and the LF pulse. As shown in Fig. 6, the LF pulse is turned off between the 8th cycle and the 10th cycle, which is the interval period of the LF pulse. Also, in Modification 2, the HF pulse is turned off between the 6th cycle and the 10th cycle, which is the interval period of the HF pulse. In this way, in Modification 2, an interval period is provided for both the HF pulse and the LF pulse.

[0046] A pulse of an HF pulse indicated by a pulse frequency F1 and a pulse of an LF pulse indicated by a pulse frequency F2 frequencyIn the example of Figure 6, it is 1KHz. The duty ratio of the HF pulse (Duty1) is 50%, and the duty ratio of the LF pulse (Duty2) is 25%. There is a phase difference between HF and LF, and LF is turned on when HF is turned off. The phase difference between HF and LF and the on / off timing are the same in the 1st to 5th cycles. However, HF and LF may be synchronized.

[0047] Interval Period Repetition frequency is repetition The frequency F3 is Pulse Frequency F1 and Pulse Lower than frequency F2. Pulse Frequency F1 and Pulse Frequency F2 is repetition It is 10 times the frequency F3. In the example of Fig. 6, the interval period during which the HF is continuously in the off state is set to 50% of the total time of the repeated on / off cycle of the HF pulse indicated by Duty1 (total cycle time of 1 cycle to 5 cycles) and the HF interval period. The interval period during which the LF is continuously in the off state is set to 30% of the total time of the repeated on / off cycle of the LF pulse indicated by Duty2 (total cycle time of 1 cycle to 7 cycles) and the LF interval period.

[0048] Duty 3 is set to 50% of the total time during which the HF pulse repeats on and off as indicated by Duty 1 (total cycle time of 1 to 5 cycles) and the interval period during which the HF is continuously in the off state. Duty 4 is set to 70% of the total time during which the LF pulse repeats on and off as indicated by Duty 2 (total cycle time of 1 to 7 cycles) and the interval period during which the LF is continuously in the off state.

[0049] When Duty3 is 50% and Duty4 is 70%, the HF pulse and LF pulse are turned on and off periodically during the 1st to 5th cycles. During the 6th to 7th cycles, the LF pulse is turned on and off periodically, but the HF is controlled to be off. During the 8th to 10th cycles, both the HF pulse and the LF pulse are turned off. The effect of Modification 2 is generally the same as that of Modification 3, except that the effect of the 6th to 7th cycles becomes the effect of the 9th to 10th cycles of Modification 3, and the effect of the 8th to 10th cycles becomes the effect of the 6th to 8th cycles of Modification 3.

[0050] (Variation 3) Next, Modification 3 in which an interval period is provided between the HF pulse and the LF pulse will be described with reference to Fig. 7. Fig. 7 is a diagram for explaining a plasma processing method according to Modification 3. Modification 3 is different from Modification 2 in that the LF is shifted by -20%, and the other configurations are the same.

[0051] In the case of the third modification, in the first to fifth cycles, the HF pulse is turned on, and then the LF pulse is controlled to be turned on. Therefore, while the HF pulse is on, as shown in FIG. 7(a), the HF contributes to the generation of plasma and radicals, and ions, electrons, and radicals are generated. Also, while the LF pulse is on, as shown in FIG. 7(b), the LF draws high-energy ions into the recesses of the film 101 to be etched. As a result, etching is mainly promoted by the ions with high energy. The ion energy is high, the etching rate is fast, and the ion incidence angle is relatively narrow, so that etching tends to proceed vertically.

[0052] In the sixth to eighth cycles, the HF pulse and the LF pulse are turned off. Therefore, the plasma and radicals are attenuated, and as shown in FIG. 7(c), the exhaust of by-products from the recesses of the film 101 to be etched is further promoted. In the ninth to tenth cycles, only the LF pulse is turned on. Since the HF is turned off, as shown in FIG. 7(d), etching is promoted by ions of medium energy since the HF does not contribute to the generation of plasma and radicals. The etching rate is medium due to the ions with medium ion energy, and damage to the mask 102 is reduced. In this way, the amount of damage to the mask 102 can be adjusted by adjusting the shift amount of the HF and LF.

[0053] (Variation 4) Next, a fourth modification in which an interval period is provided between the HF pulse and the LF pulse will be described with reference to Fig. 8. Fig. 8 is a diagram for explaining a plasma processing method according to the fourth modification. The fourth modification is different from the second modification in Fig. 6 in that the interval period of the HF pulse is longer than the interval period of the LF pulse, whereas the fourth modification is different in that the interval period of the HF pulse is shorter than the interval period of the LF pulse.

[0054] In the case of the fourth modification, in the first to sixth cycles, the HF pulse is turned on, and then the LF pulse is controlled to be turned on. Therefore, while the HF pulse is on, as shown in FIG. 8(a), the HF contributes to the generation of plasma and radicals, and ions, electrons, and radicals are generated. Also, while the LF pulse is on, as shown in FIG. 8(b), the LF draws high-energy ions into the recesses of the film 101 to be etched. As a result, etching is mainly promoted by the ions having high energy. The ion energy is high, the etching rate is fast, the ion incidence angle is relatively narrow, and etching tends to proceed vertically, but the damage to the mask 102 is large. However, since there is a phase difference between the HF and LF and the LF is shifted by -20%, the damage to the mask 102 is improved compared to when the HF and LF are synchronized.

[0055] In the seventh to eighth cycles, the HF pulse is repeatedly turned on and off, and the LF pulse is turned off. While the HF pulse is on, as shown in Fig. 8(a), the HF contributes to the generation of plasma and radicals, and ions, electrons, and radicals are generated. Also, because the LF pulse is off, as shown in Fig. 8(c), ions with weaker energy than those in the first to sixth cycles etch the top and sides of the mask 102, removing by-products adhering to the sides of the mask.

[0056] In the ninth to tenth cycles, the HF pulse and the LF pulse are turned off. Therefore, the plasma and radicals are attenuated and there is no attraction of ions by the LF, so that exhaust of by-products from the recesses of the etching target film 101 is further promoted, as shown in FIG. 8(d).

[0057] As described above, according to the inventions relating to Modifications 1 to 4, by providing an interval period during which LF and HF are turned off, it is possible to further prevent mask clogging and increase exhaust efficiency.

[0058] Also, in the inventions according to Modifications 1 to 4, while the HF is on, the HF contributes to the generation of plasma and radicals, and ions, electrons, and radicals are generated. While the LF is on, etching is mainly promoted by ions having high energy. This makes it possible to maintain the etching rate and improve the throughput. Also, by providing a phase difference between the HF and LF and turning on the LF after the HF is on, damage to the mask 102 can be improved.

[0059] In the inventions according to Modifications 1 to 4, the pulse of the HF pulse is also frequency F1 and LF pulses frequency At least one of F2 is set to the interval period. Repetition rateF3 is set to 5 times or more. In addition, the duty ratio of the HF pulse (Duty 1) and the duty ratio of the LF pulse (Duty 2) are output at 90% or less. Then, the substrate is processed by plasma generated from the processing gas supplied into the processing vessel according to the output of the HF pulse and the LF pulse.

[0060] (Other variations) HF pulsed pulse frequency Show Pulse The frequency F1 may be set to be equal to or greater than 1 KHz and equal to or less than 20 KHz.

[0061] Duty1 is set to 90% or less. If Duty1 is set to 90% or more, the possibility of mask clogging increases, and the promotion of exhaust of by-products from recesses in the etching target film 101 is hindered. Furthermore, Duty1 is preferably 10% or more and 90% or less. If Duty1 is less than 10%, the time that HF ​​is turned on is short, and there is a possibility that plasma will not be ignited.

[0062] LF Pulse Interval period in of Repetition rate Show repetition The frequency F3 may be set to 0.1 KHz or more and 1 KHz or less. Duty2 is preferably set to 10% or more and 90% or less. If Duty2 is set to less than 10%, the time that LF is turned on is shortened, and the exhaust of by-products from the recesses of the etching target film 101 is improved, but the etching rate is reduced. If Duty2 is set to more than 90%, the etching rate is increased, but the exhaust of by-products from the recesses of the etching target film 101 is deteriorated, which may cause mask clogging (mask blockage) and cause an etch stop.

[0063] Furthermore, it is more preferable that Duty2 is 60% or more and 80% or less. This further optimizes the interval for turning off the LF, thereby optimizing the balance between exhaust of by-products and the etching rate, and while avoiding mask clogging, it is possible to maintain the etching rate and improve throughput.

[0064] Pulse The frequency F1 is repetition It is set to be at least five times the frequency F3. Pulse The frequency F1 is repetition It is more preferable that the frequency is 10 times or more the frequency F3, which allows sufficient time for exhausting the by-products and suppresses mask clogging.

[0065] The HF pulse and the LF pulse may have a phase difference. In other words, the timing of the on-time of the LF pulse and the on-time of the HF pulse may be shifted. For example, the on-time of the LF pulse and the on-time of the HF pulse may be shifted by 100%. When the on-time of the LF pulse and the on-time of the HF pulse are shifted by 100%, the on-time of the LF pulse and the on-time of the HF pulse do not overlap.

[0066] The HF pulse has a power in the range of, for example, 300 W to 2400 W. The LF pulse has a power in the range of, for example, 500 W to 7000 W.

[0067] The control unit 2, within the scope described above, (1) Pulse Frequency F1, (2) Duty1, (3) repetition Frequency F3, (4) Duty2, and (5) Pulse Frequency F1 is repetition The frequency is controlled so as to satisfy all five conditions (1) to (5), ie, that the frequency is five times or more the frequency F3. Under these conditions, the plasma processing method according to the present embodiment is performed.

[0068] Of the above five conditions, an example has been described in which the power is controlled to 0 W during the HF off time, but instead of turning the HF off, it may be controlled to Low. Controlling the HF to Low means outputting an HF with a power higher than 0 W and lower than the output level of the HF output during the on time.

[0069] Similarly, an example has been described in which the power is controlled to 0 W during the off time of the LF, but the LF may be controlled to Low instead of being turned off. Controlling the LF to Low refers to control in which the LF is output with a power higher than 0 W and a lower power than the output level of the LF output during the on time.

[0070] When HF is controlled to low, more radicals can be generated than when HF is controlled to off, so radicals can be controlled. Therefore, when radical control is desired, it is better to control HF to low than to turn it on and then off. HF has a higher frequency than LF, so ions cannot follow the change in HF frequency. For this reason, radicals are mainly controlled by controlling HF to low.

[0071] When LF is controlled to low, ions can be controlled more than when LF is controlled to off. Because LF has a lower frequency than HF, ions can follow the change in LF frequency. Therefore, by controlling LF to low, ions can be mainly controlled.

[0072] As described above, according to the plasma processing apparatus and plasma processing method of this embodiment, by providing an interval period during which the LF is controlled to be off or low, mask clogging can be avoided and throughput can be improved.

[0073] In addition, by adjusting various parameters in each cycle shown in the plasma processing method according to this embodiment, it is possible to achieve a high selectivity ratio of the mask to the film 101 to be etched. For example, the various parameters include the time of each step (on, off, etc.) of each cycle, the gas ratio of the processing gas used in the plasma processing, the set output of HF and LF (high power, low power), the pulse of HF and LF, etc. frequency ( Pulse Frequency F1, Pulse These include the frequency F2), and the HF and LF duty ratios (Duty1, Duty2).

[0074] The plasma processing apparatus and the plasma processing method according to the embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0075] The plasma processing apparatus of the present disclosure can be any type of apparatus, including an atomic layer deposition (ALD) apparatus, a capacitively coupled plasma (CCP) apparatus, and an inductively coupled plasma (ICP) apparatus. [Explanation of symbols]

[0076] 1. Plasma processing equipment 2. Control section 2a Computer 2a1 Processing section 2a2 Storage section 2a3 Communication Interface 10 Plasma Processing Chamber 11 Substrate support 13. Shower Head 21 Gas Source 20 Gas supply section 30 power supply 31 RF power supply 31a First RF generation unit 31b Second RF generation unit 32a First DC generation unit 32b Second DC generation section 40 Exhaust system 100 Silicon substrate 101 Film to be etched 102 Mask 111 Main body 112 Ring Assembly

Claims

1. a processing vessel capable of being evacuated; a first electrode disposed in the processing chamber and supporting a substrate to be processed; a second electrode or antenna provided opposite the first electrode; a first high frequency power supply unit connected to the first electrode, the second electrode, or the antenna and configured to supply a plurality of successive first high frequency power pulses for plasma generation to the first electrode, the second electrode, or the antenna; a second high frequency power supply connected to the first electrode and configured to supply a plurality of continuous second high frequency power pulses for biasing to the first electrode in synchronization with the first high frequency power pulses; a control unit that controls the first high frequency power supply unit and the second high frequency power supply unit, The control unit is In an etching process for an etching target film of the substrate to be processed, providing an interval period for either the first high frequency power pulse or the second high frequency power pulse, and not providing the interval period for the other of the first high frequency power pulse or the second high frequency power pulse; a first pulse frequency of the first high frequency power pulse and a second pulse frequency of the second high frequency power pulse are set to be 5 times or more the repetition frequency of the interval period; The first high frequency power pulse and the second high frequency power pulse are output with a duty ratio of 90% or less, controlling the processing target substrate to be processed by plasma generated from a processing gas supplied into the processing chamber in response to outputs of the first high frequency power pulse and the second high frequency power pulse; Plasma processing equipment.

2. The duty ratio of the interval period is 10% or more and 90% or less. The plasma processing apparatus according to claim 1 .

3. The duty ratio of the interval period is 60% or more and 80% or less. The plasma processing apparatus according to claim 2 .

4. a processing vessel capable of being evacuated; a first electrode disposed in the processing chamber and supporting a substrate to be processed; a second electrode or antenna provided opposite the first electrode; a first high frequency power supply unit connected to the first electrode, the second electrode, or the antenna and configured to supply a plurality of successive first high frequency power pulses for plasma generation to the first electrode, the second electrode, or the antenna; a second high frequency power supply connected to the first electrode and configured to supply a plurality of continuous second high frequency power pulses for biasing to the first electrode in synchronization with the first high frequency power pulses; a control unit that controls the first high frequency power supply unit and the second high frequency power supply unit, The control unit is In an etching process for an etching target film of the substrate to be processed, providing a first interval period for the first high frequency power pulse and providing a second interval period for the second high frequency power pulse, the second interval period being different from the first interval period; setting a first pulse frequency of the first high frequency power pulse and a second pulse frequency of the second high frequency power pulse to 5 times or more the repetition frequency of the first interval period and the second interval period; The first high frequency power pulse and the second high frequency power pulse are output with a duty ratio of 90% or less, controlling the processing target substrate to be processed by plasma generated from a processing gas supplied into the processing chamber in response to outputs of the first high frequency power pulse and the second high frequency power pulse; Plasma processing equipment.

5. The duty ratio of each of the first interval period and the second interval period is 10% or more and 90% or less. The plasma processing apparatus according to claim 4 .

6. The duty ratio of each of the first interval period and the second interval period is 60% or more and 80% or less. The plasma processing apparatus according to claim 5 .

7. The first pulse frequency and the second pulse frequency are 10 times or more the repetition frequency. The plasma processing apparatus according to claim 1 .

8. The duty ratio of the first high frequency power pulse and the second high frequency power pulse is 10% or more and 90% or less. The plasma processing apparatus according to claim 1 .

9. The repetition frequency is 0.1 KHz or more and 1 KHz or less. The plasma processing apparatus according to claim 1 .

10. The first pulse frequency and the second pulse frequency are 1 KHz or more and 20 KHz or less. The plasma processing apparatus according to claim 1 .

11. the first radio frequency power pulse and the second radio frequency power pulse have a phase difference; The plasma processing apparatus according to claim 1 .

12. a processing vessel capable of being evacuated; a first electrode disposed in the processing chamber and supporting a substrate to be processed; a second electrode or antenna provided opposite the first electrode; a first high frequency power supply unit connected to the first electrode, the second electrode, or the antenna and configured to supply a plurality of successive first high frequency power pulses for plasma generation to the first electrode, the second electrode, or the antenna; a second high frequency power supply connected to the first electrode and configured to supply a plurality of continuous second high frequency power pulses for biasing to the first electrode in synchronization with the first high frequency power pulses; A plasma processing method performed in a plasma processing apparatus comprising: In an etching process for an etching target film of the substrate to be processed, providing an interval period for either the first high frequency power pulse or the second high frequency power pulse, and not providing the interval period for the other of the first high frequency power pulse or the second high frequency power pulse; a first pulse frequency of the first high frequency power pulse and a second pulse frequency of the second high frequency power pulse are set to be 5 times or more the repetition frequency of the interval period; The first high frequency power pulse and the second high frequency power pulse are output with a duty ratio of 90% or less, the substrate is processed by plasma generated from a processing gas supplied into the processing chamber in response to outputs of the first high frequency power pulse and the second high frequency power pulse. Plasma treatment method.

13. A processing vessel capable of being evacuated to a vacuum; a first electrode disposed in the processing chamber and supporting a substrate to be processed; a second electrode or antenna provided opposite the first electrode; a first high frequency power supply unit connected to the first electrode, the second electrode, or the antenna and configured to supply a plurality of successive first high frequency power pulses for plasma generation to the first electrode, the second electrode, or the antenna; a second high frequency power supply connected to the first electrode and configured to supply a plurality of continuous second high frequency power pulses for biasing to the first electrode in synchronization with the first high frequency power pulses; A plasma processing method performed in a plasma processing apparatus comprising: In an etching process for an etching target film of the substrate to be processed, providing a first interval period for the first high frequency power pulse and providing a second interval period for the second high frequency power pulse, the second interval period being different from the first interval period; setting a first pulse frequency of the first high frequency power pulse and a second pulse frequency of the second high frequency power pulse to 5 times or more the repetition frequency of the first interval period and the second interval period; The first high frequency power pulse and the second high frequency power pulse are output with a duty ratio of 90% or less, the substrate is processed by plasma generated from a processing gas supplied into the processing chamber in response to outputs of the first high frequency power pulse and the second high frequency power pulse. Plasma treatment method.

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