JP2022117670A - Plasma processing apparatus and plasma processing method - Google Patents

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

The present disclosure relates to a plasma processing apparatus and a plasma processing method.

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 with a frequency lower than the frequency of the high-frequency power for plasma generation are applied to a mounting table. do. In this plasma processing method, a pulse wave of high-frequency power for plasma generation and a pulse wave of high-frequency power for bias have a phase difference, and the duty ratio of the high-frequency power for plasma generation is the duty ratio of the high-frequency power for bias. Control to be above. Thereby, an offset is provided between the pulse wave of the high-frequency power for plasma generation and the pulse wave of the high-frequency power for bias.

JP 2016-157735 A

In order to suppress or improve bowing of etched recesses, variation in CD size, mask distortion and blockage, etc., it is important to finely control radicals, ion density, ion incident angle, sidewall protection, and the like.

The present disclosure provides techniques that can improve the performance of processes performed in plasma processing apparatuses.

According to one aspect of the present disclosure, a processing container that can be evacuated, a first electrode that is arranged in the processing container and supports a substrate to be processed, and a second electrode that faces the first electrode or an antenna, and a first high frequency connected to the first electrode, the second electrode or the antenna and supplying a first high frequency power pulse for plasma generation to the first electrode, the second electrode or the antenna a power supply unit, a second high frequency power supply unit connected to the first electrode for supplying a second high frequency power pulse for biasing to the first electrode, the first high frequency power supply unit and the first and a control unit for controlling the high-frequency power supply unit of No. 2, wherein the control unit provides an interval period for either the first high-frequency power pulse or the second high-frequency power pulse, and the first At least one of the pulse period of the high-frequency power pulse and the pulse period of the second high-frequency power pulse is set to be five times or more the period of the interval period, and the first high-frequency power pulse and the second high-frequency power pulse A substrate to be processed by plasma generated from a processing gas supplied into the processing chamber according to the outputs of the first high-frequency power pulse and the second high-frequency power pulse, with a duty ratio of 90% or less. A plasma processing apparatus is provided, the plasma processing apparatus being controlled to process the

According to one aspect, it is possible to improve the performance of the process performed in the plasma processing apparatus.

1 is a schematic cross-sectional view showing an example of a plasma processing system according to an embodiment; FIG. The figure which shows an example of the conventional plasma processing method. The figure which shows an example of the plasma processing method which concerns on embodiment. FIG. 4 is a diagram for explaining the plasma processing method according to the embodiment; FIG. 5 is a diagram showing an example of a plasma processing method according to Modification 1; FIG. 10 is a diagram showing an example of a plasma processing method according to Modification 2; FIG. 11 is a diagram for explaining a plasma processing method according to Modification 3; FIG. 11 is a diagram for explaining a plasma processing method according to Modification 4;

Hereinafter, embodiments for carrying out the present disclosure will be described with reference to the drawings. In each drawing, the same components are denoted by the same reference numerals, and redundant description may be omitted.

[Plasma treatment system]
A configuration example of the plasma processing system will be described below. The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a controller 2 . The plasma processing apparatus 1 includes an evacuable plasma processing chamber 10 , a gas supply 20 , a power supply 30 and an exhaust system 40 . Further, the plasma processing apparatus 1 includes a substrate supporting portion 11 and a gas introducing portion. The gas introduction is configured to introduce at least one process gas into the plasma processing chamber 10 . The gas introduction section includes a showerhead 13 . A substrate support 11 is positioned within the plasma processing chamber 10 . The showerhead 13 is arranged above the substrate support 11 . In embodiments, showerhead 13 forms at least a portion of the ceiling of plasma processing chamber 10 . The interior of the plasma processing chamber 10 has a plasma processing space 10 s defined by the shower head 13 , sidewalls 10 a of the plasma processing chamber 10 and the substrate support 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. . Side wall 10a is grounded. The showerhead 13 and substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10 .

The substrate support portion 11 includes a body portion 111 and a ring assembly 112 . The body portion 111 has a central region (substrate support surface) 111 a for supporting a substrate W, an example of which is a wafer, and an annular region (ring support surface) 111 b for supporting the ring assembly 112 . The annular region 111b of the body portion 111 surrounds the central region 111a of the body portion 111 in plan view. The substrate W is arranged on the central region 111 a of the main body 111 , and the ring assembly 112 is arranged on the annular region 111 b of the main body 111 so as to surround the substrate W on the central region 111 a of the main body 111 . In embodiments, the main body 111 includes a base and an electrostatic chuck. The base includes an electrically conductive member. The conductive member of the base functions as a lower electrode. An electrostatic chuck is arranged on the base. The top surface of the electrostatic chuck has a substrate support surface 111a. Ring assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring. Also, although not shown, the substrate supporter 11 may include a temperature control module configured to control at least one of the electrostatic chuck, the ring assembly 112, and the substrate W to a target temperature. The temperature control module may include heaters, heat transfer media, flow paths, or combinations thereof. A heat transfer fluid, such as brine or gas, flows through the flow path. Further, the substrate support section 11 may include a heat transfer gas supply section configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

The showerhead 13 is configured to introduce at least one processing gas from the gas supply 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas introduction ports 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s through a plurality of gas introduction ports 13c. Showerhead 13 also includes a conductive member. A conductive member of the showerhead 13 functions as an upper electrode. In addition to the showerhead 13, the gas introduction part may include one or more side gas injectors (SGI: Side Gas Injectors) attached to one or more openings formed in the side wall 10a.

Gas supply 20 may include at least one gas source 21 and at least one flow controller 22 . In embodiments, 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, gas supply 20 may include one or more flow modulation devices that modulate or pulse the flow rate of at least one process gas.

Power supply 30 includes an RF power supply 31 coupled to plasma processing chamber 10 via at least one impedance match circuit. RF power supply 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to conductive members of substrate support 11 and/or conductive members of showerhead 13 . be done. Thereby, plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Accordingly, RF power source 31 may function as at least part of a plasma generator configured to generate a plasma from one or more process gases in plasma processing chamber 10 . Further, by supplying the bias RF signal to the conductive member of the substrate supporting portion 11, a bias potential is generated in the substrate W, and ion components in the formed plasma can be drawn into the substrate W. FIG.

In an embodiment, the RF power supply 31 includes a first RF generator 31a and a second RF generator 31b. The first RF generator 31a is coupled to the conductive member of the substrate support 11 or the conductive member of the showerhead 13 via at least one impedance matching circuit to generate a source RF signal (source RF power) for plasma generation. is configured to generate In embodiments, the source RF signal has a frequency within the range of 13 MHz to 150 MHz. In embodiments, the first RF generator 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are provided to conductive members of the substrate support 11 or conductive members of the showerhead 13 . The second RF generator 31b is coupled to the conductive member of the substrate support 11 via at least one impedance matching circuit and configured to generate a bias RF signal (bias RF power). In embodiments, the bias RF signal has a lower frequency than the source RF signal. In embodiments, the bias RF signal has a frequency within 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. One or more bias RF signals generated 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.

The conductive member of the base of the substrate supporter 11 provided inside the plasma processing chamber 10 is an example of a first electrode arranged inside the processing chamber and supporting the substrate to be processed. The conductive member of the showerhead 13 is an example of a second electrode provided to face the first electrode. Instead of the showerhead 13, which is an example of the second electrode, an antenna may be provided facing the first 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 above the plasma processing chamber 10 so as to face the first electrode supporting the substrate to be processed, and the first RF generator 31a may be connected to the antenna.

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

Power supply 30 may also include a DC power supply 32 coupled to 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 members of substrate support 11 . In embodiments, the first DC signal may be applied to other electrodes, such as electrodes in an electrostatic chuck. In an embodiment, the second DC generator 32b is connected to the conductive member of the showerhead 13 and configured to generate a second DC signal. The generated second DC signal is applied to the conductive members of showerhead 13 . In various embodiments, at least one of the first and second DC signals may be pulsed. A first DC generator 32 a and a second DC generator 32 b are provided in addition to the RF power supply 31 .

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

Controller 2 processes computer-executable instructions that cause plasma processing apparatus 1 to perform the various steps described in this disclosure. Controller 2 may be configured to control elements of plasma processing apparatus 1 to perform the various processes described herein. For example, the controller 2 controls the first RF generator 31a and the second RF generator 31b. In embodiments, part or all of the controller 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. Processing unit 2a1 can be configured to perform various control operations based on programs stored in storage unit 2a2. The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

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. FIG. Note that the plasma processing method according to the embodiment is controlled by the controller 2 . The source RF signal supplied from the first RF generator 31a is also referred to as first high frequency power or HF. A 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 generator 31b is also referred to as second high frequency power or LF. A pulse wave of the second high-frequency power is also referred to as an LF pulse.

[Conventional plasma processing method]
FIG. 2 is a diagram showing an example of a conventional plasma processing method. In conventional plasma processing methods, 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 HF and LF are shifted by 40% based on the time when HF is turned ON, and the ON times (supply time, application time) of HF and LF do not overlap. LF is turned on when HF is turned off (supply is stopped). 40% of the cycle has HF on, 25% has LF on, and 35% has both HF and LF off for a total of 100%.

Plasma and radicals are generated while the HF is turned on. While the LF is on, ions in the plasma are attracted to the substrate, promoting etching. While HF and LF are turned off, by-products (reaction products) generated during etching are exhausted from recesses formed in the etching target.

A high LF power is required to achieve high anisotropic etching while maintaining a high etching rate, that is, to achieve verticality of the etched shape. However, in the example of FIG. 2, while the LF is turned on, high-energy ions are applied to the film to be etched on the substrate by applying high-output LF power, while high-energy ions The mask can also be removed by etching. In addition, a large amount of byproducts adhere to the mask due to the promotion of etching by high-energy ions. This causes clogging of the mask above the film to be etched. Mask clogging refers to narrowing or complete blockage of the mask opening due to adhesion of by-products to the sidewalls of the mask. As a method of avoiding clogging of the mask, there is a method of turning off both the HF and the LF and setting a time (Off Time) to promote evacuation. However, if the LF is turned off for a short time, the by-products are not efficiently discharged from the concave portions of the etching object.

Therefore, in the plasma processing method according to the embodiment described below, the on and off times of the HF pulse and the LF pulse are controlled, and the on and off times of the LF are set at a lower frequency. This avoids mask clogging.

[Plasma processing method according to the embodiment]
A plasma processing method according to an embodiment will be described with reference to FIGS. 3 and 4. FIG. FIG. 3 is a diagram showing an example of the plasma processing method according to the embodiment. FIG. 4 is a diagram for explaining the plasma processing method according to the embodiment.

In the plasma processing method according to the embodiment, as shown in FIG. 3, an HF pulse frequency F1 (hereinafter also simply referred to as frequency F1) and an LF pulse frequency F2 (hereinafter also simply referred to as frequency F2) are set. , controls the cycle of turning on and off. The pulse period of the HF pulse indicated by pulse frequency F1 and the LF pulse indicated by pulse frequency F2 is 1 KHz in the example of FIG. The duty ratio (Duty1) of the HF pulse and the duty ratio (Duty2) of the LF pulse are 50%. HF and LF are synchronous, and the ON timing and OFF timing of HF and LF are the same in the first cycle and the second cycle. Note that Duty1 indicates the ON time of HF with respect to the total time of ON time and OFF time of HF. Also, Duty2 indicates the ON time of the LF with respect to the total time of the ON time and OFF time of the LF. The on-time and off-time of HF and LF are synchronized in the first and second cycles. However, HF and LF may be out of phase.

The LF pulse is turned off during the 3rd to 10th cycles. The time during which the LF pulse is turned off is also called an interval period. A pulse frequency F3 (hereinafter also simply referred to as frequency F3) indicates an interval period of the LF pulse (interval period of the LF pulse). Frequency F3, which is an interval period, is lower than frequency F1 and frequency F2. In the example of FIG. 3, frequencies F1 and F2 are ten times frequency F3. The interval period of the LF pulses, indicated by frequency F3, is 0.1 KHz in the example of FIG. Duty3 is the time to repeat the on/off cycle of the LF pulse indicated by Duty2 (total time of 1 cycle and 2 cycles in FIG. 3) and the total time of LF OFF time (total time of 3 to 10 cycles in FIG. 3 ) to repeat the on/off cycle of the LF pulse. 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.

In the example of FIG. 3, the interval period in which LF is continuously turned off is the total time of repeating the on/off cycle of the LF pulse indicated by Duty2 (total cycle time of 1 cycle and 2 cycles) and LF. It is set to 80% of the total time with the interval period. Duty3 is set to 20% of the total time of the LF pulse repeating ON and OFF indicated by Duty2 (total cycle time of 1 cycle and 2 cycles) and the interval period in which LF is continuously turned off. .

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 ten times. The on/off of the HF pulse and LF pulse is periodically repeated between the first cycle and the second cycle. During the 3rd to 10th cycles, the on/off of the HF pulse is periodically repeated in the 1st and 2nd cycles, but the LF is controlled to be off. The example of FIG. 3 shows an example in which the LF pulse is synchronized with the HF pulse in the 1st and 2nd cycles, but the present invention is not limited to this, and the LF pulse may be synchronized with the HF pulse in the 3rd and subsequent cycles. .

The controller 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 outputs of the HF pulse and the LF pulse. Accordingly, mask clogging can be avoided by providing an interval period in which only the LF is turned off. The reason will be described with reference to FIG.

In this embodiment, for example, a SiO ₂ 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.

In period A of the first cycle shown in FIG. 4, the HF pulse and LF pulse are controlled to be on. Therefore, as shown in the upper part of FIG. 4A, HF contributes to the generation of plasma and radicals, and ions, electrons, and radicals are generated. Further, as shown in the lower part of FIG. 4A, the LF draws high-energy ions into the concave portion of the etching target film 101 . Accordingly, in period A, etching is mainly promoted by ions having high energy. The ion energy is high, the etching rate is high, the incident angle of the ions is relatively narrow, and the etching tends to progress vertically, but the damage to the mask 102 is large.

In the B period of the 1st cycle, the HF pulse and LF pulse are controlled to be off. Therefore, in period B, the plasma and radicals generated in period A are attenuated, and as shown in the upper part of FIG. It is discharged from the concave portion of the target film 101, and the evacuation is facilitated. In addition, as shown in the lower part of FIG. 4B, ions having weaker energy than the ions in the period A etch the top and sides of the mask 102, resulting in by-products adhering to the sides of the mask. remove things.

In periods A and B of the second cycle, the same operation as in the first cycle is repeated, and etching is mainly promoted in the A period, and exhaust is mainly promoted in the B period.

During the 3rd to 10th 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, similarly to the 1st and 2nd cycles.

In the C period of the third cycle, HF is controlled to be on and LF is controlled to be off. Therefore, plasma and radicals are generated by HF, as shown in the upper part of FIG. 4(c). In addition, since there is no ion attraction by the LF, as shown in the lower part of FIG.

During the D period of the third cycle, the HF and LF pulses are turned off. Therefore, since the plasma and radicals are attenuated and LF does not attract ions, as shown in the upper part of FIG. In the 3rd cycle to the 10th cycle, the decrease in (c) and (d) is repeated, so that by-products can be actively exhausted from the recessed portions of the film 101 to be etched. By thus providing an interval period for turning off the LF, clogging of the mask can be avoided and the throughput can be improved.

[Modification]
(Modification 1)
Next, Modification 1 in which the HF pulse is provided with an interval period will be described with reference to FIG. FIG. 5 is a diagram showing an example of a plasma processing method according to Modification 1. As shown in FIG. In Modification 1, the HF pulse is turned off during the 8th cycle to the 10th cycle, which is the interval period of the HF pulse. Further, in Modification 1, the LF pulse is not provided with an interval period.

The pulse period of the HF pulse indicated by the pulse frequency F1 and the LF pulse indicated by the pulse frequency F2 is 1 KHz in the first modification. The duty ratio of the HF pulse (Duty1 is 50%, and the duty ratio of the LF pulse (Duty2) is 25%. HF and LF are synchronized, and the timing of turning on HF and LF in the 1st to 7th cycles are the same, and the turn-off timing of LF is earlier than that of HF, although there may be a phase difference between HF and LF.

Frequency F3, which is an interval period, is lower than frequency F1 and frequency F2. Frequencies F1 and F2 are ten times the frequency F3. In modification 1, the interval period in which HF is continuously turned off is the total time of repeating the on/off cycle of the HF pulse indicated by Duty1 (total cycle time of 1 cycle to 7 cycles) and the interval of HF It is set to 30% of the total time with the period. Duty3 is set to 70% of the total time of the HF pulse repeating ON and OFF indicated by Duty1 (total cycle time of 1 cycle to 7 cycles) and the interval period in which HF is continuously turned off. .

When Duty3 is 70%, the on/off cycle of the HF pulse is repeated seven times while the on/off cycle of the LF pulse is repeated ten times. During the 1st to 7th cycles, the HF pulse and the LF pulse are periodically turned on/off. During the 8th to 10th cycles, the LF pulse is periodically turned on/off, but the HF is controlled to be off. Modification 1 shows an example in which the LF pulse is synchronized with the HF pulse in the 1st to 7th cycles, but is not limited to this.

In the case of Modification 1, the operations (a) and (b) shown in periods A and B in FIG. 4 are repeated in the 1st to 7th cycles. However, in Modification 1, since the ON time of the LF is shorter than in the embodiment, the degree of attraction of ions with high energy is reduced, and the etching rate is reduced, but the damage to the mask is reduced. In the interval period of the 8th cycle to the 10th cycle, the LF pulse is repeatedly turned on and off, and the HF pulse is controlled to be off. As a result, collisions between reaction products and ions during etching are suppressed, and the mask selectivity is improved. Further, in the interval period of HF from the 8th cycle to the 10th cycle, the electron density in the plasma decreases, so the incident angle of ions is relatively narrow and the etching tends to proceed vertically. The above is the effect of Modification 1 in which the interval period is provided in the HF pulse.

(Modification 2)
Next, Modification 2 in which the HF pulse and the LF pulse are provided with an interval period will be described with reference to FIG. FIG. 6 is a diagram showing an example of a plasma processing method according to Modification 2. In FIG.

In Modification 2, both the HF pulse and the LF pulse are provided with an interval period. As shown in FIG. 6, the LF pulse is turned off during the 8th to 10th cycles, which is the interval period of the LF pulse. In the second modification, the HF pulse is turned off during the 6th cycle to the 10th cycle, which is the interval period of the HF pulse. Thus, in Modification 2, both the HF pulse and the LF pulse are provided with an interval period.

The pulse period of the HF pulse indicated by pulse frequency F1 and the LF pulse indicated by pulse frequency F2 is 1 KHz in the example of FIG. The duty ratio (Duty1) of the HF pulse is 50%, and the duty ratio (Duty2) of the LF pulse is 25%. There is a phase difference between HF and LF, and LF is turned on at the timing when HF is turned off. The phase difference and on/off timing between HF and LF are the same in the 1st to 5th cycles, but HF and LF may be synchronized.

Frequency F3, which is an interval period, is lower than frequency F1 and frequency F2. Frequencies F1 and F2 are ten times the frequency F3. In the example of FIG. 6, the interval period in which HF is continuously turned off is the total time of repeating the on/off cycle of the HF pulse indicated by Duty1 (total cycle time of 1 cycle to 5 cycles) and HF. It is set to 50% of the total time with the interval period. The interval period in which the LF is continuously off is the total time of repeating the on/off cycle of the LF pulse indicated by Duty2 (total cycle time of 1 cycle to 7 cycles) and the interval period of the LF. is set to 30% of

Duty3 is set to 50% of the total time of the HF pulse repeating ON and OFF indicated by Duty1 (total cycle time of 1 cycle to 5 cycles) and the interval period in which HF is continuously turned off. . Duty4 is set to 70% of the total time of the LF pulse repeating ON and OFF indicated by Duty2 (total cycle time of 1 cycle to 7 cycles) and the interval period in which LF is continuously turned off. .

When Duty3 is 50% and Duty4 is 70%, the HF pulse and LF pulse are periodically turned on/off during the 1st to 5th cycles. During the 6th and 7th cycles, the on/off of the LF pulse is periodically repeated, but the HF is controlled to be off. Both the HF and LF pulses are turned off during the 8th to 10th cycles. The effect of Modification 2 is that the effect of the 6th to 7th cycles is the effect of the 9th to 10th cycles of Modification 3, and the effect of the 8th to 10th cycles is the effect of the 6th to the 6th cycles of Modification 3. The effect is substantially the same as that of Modified Example 3 below, except that the effect is the eighth cycle.

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

In the case of modification 3, the LF pulse is turned on after the HF pulse is turned on in the 1st to 5th cycles. Therefore, while the HF pulse is on, as shown in FIG. 7A, HF contributes to the generation of plasma and radicals, generating ions, electrons, and radicals. Further, while the LF pulse is on, as shown in FIG. 7B, the LF draws high-energy ions into the concave portion of the etching target film 101 . Thereby, etching is mainly promoted by ions having high energy. The ion energy is high, the etching rate is high, the incident angle of the ions is relatively narrow, and the etching tends to proceed vertically.

In the 6th to 8th cycles, the HF and LF pulses are turned off. Therefore, the plasma and radicals are attenuated, and as shown in FIG. Only the LF pulse is turned on in the 9th to 10th cycles. Since the HF is turned off, as shown in FIG. 7(d), ions of moderate energy accelerate the etching because the HF does not contribute to the generation of plasma and radicals. Ions with medium ion energy provide a medium etching rate and less damage to the mask 102 . By adjusting the shift amounts of HF and LF in this way, the amount of damage to the mask 102 can be adjusted.

(Modification 4)
Next, Modification 4 in which the HF pulse and the LF pulse are provided with an interval period will be described with reference to FIG. FIG. 8 is a diagram for explaining the plasma processing method according to Modification 4. As shown in FIG. In Modification 2 of FIG. 6, the interval period of the HF pulse is longer than that of the LF pulse, whereas in Modification 4, the interval period of the HF pulse is shorter than that of the LF pulse.

In the case of modification 4, the LF pulse is turned on after the HF pulse is turned on in the 1st to 6th cycles. Therefore, while the HF pulse is on, as shown in FIG. 8A, HF contributes to the generation of plasma and radicals, generating ions, electrons, and radicals. Also, while the LF pulse is on, as shown in FIG. 8B, the LF draws high-energy ions into the concave portion of the etching target film 101 . Thereby, etching is mainly promoted by ions having high energy. The ion energy is high, the etching rate is high, the incident angle of the ions is relatively narrow, and the etching tends to progress vertically, but the damage to the mask 102 is large. However, since there is a phase difference between HF and LF, and LF is shifted by -20%, damage to mask 102 is improved over the case where HF and LF are synchronized.

In the 7th and 8th 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. 8A, HF contributes to the generation of plasma and radicals, generating ions, electrons, and radicals. In addition, since the LF pulse is turned off, as shown in FIG. 8C, ions having weaker energy than the ions in the first to sixth cycles etch the top and sides of the mask 102. This removes the by-product adhering to the sides of the mask.

In the 9th to 10th cycles, the HF and LF pulses are turned off. Therefore, the plasma and radicals are attenuated, and the LF does not attract ions, so that the by-products are further expelled from the concave portions of the etching target film 101 as shown in FIG. 8(d).

As described above, according to the inventions according to Modifications 1 to 4, by providing an interval period in which LF and HF are turned off, it is possible to further avoid clogging of the mask and increase the exhaust efficiency. .

Also in the inventions according to Modifications 1 to 4, while HF is on, HF contributes to the generation of plasma and radicals, generating ions, electrons, and radicals. Etching is mainly promoted by ions having high energy while the LF is on. Thereby, the etching rate can be maintained and the throughput can be improved. Further, by providing a phase difference between HF and LF and turning on LF after HF is turned on, damage to the mask 102 can be improved.

Also in the inventions according to Modifications 1 to 4, at least one of the pulse period F1 of the HF pulse and the pulse period F2 of the LF pulse is set at least five times the period F3 of the interval period. Also, the duty ratio (Duty1) of the HF pulse and the duty ratio (Duty2) of the LF pulse are output at 90% or less. Then, control is performed so that the substrate is processed by plasma generated from the processing gas supplied into the processing chamber according to the outputs of the HF pulse and the LF pulse.

(Other modifications)
A frequency F1 indicating the pulse period of the HF pulse may be set to 1 KHz or more and 20 KHz or less.

Duty1 is set to 90% or less. This is because setting Duty 1 to 90% or more increases the possibility of clogging of the mask and inhibits the promotion of exhaust of by-products from the concave portions of the etching target film 101 . Furthermore, Duty1 is preferably 10% or more and 90% or less. This is because if Duty1 is less than 10%, the time during which HF is turned on is short, and there is a possibility that plasma will not ignite.

A frequency F3 indicating the pulse period of the LF pulse may be set to 0.1 KHz or more and 1 KHz or less. Duty2 is preferably 10% or more and 90% or less. When Duty2 is set to less than 10%, the time during which the LF is turned on is shortened, and by-products are better exhausted from the concave portions of the etching target film 101, but the etching rate is lowered. Also, if Duty2 is greater than 90%, the etching rate increases, but the exhaust of by-products from the concave portions of the etching target film 101 deteriorates, clogging of the mask (mask clogging) occurs, and etch stop occurs. there is a possibility.

Furthermore, Duty2 is more preferably 60% or more and 80% or less. As a result, by further optimizing the interval time for turning off the LF, it is possible to optimize the balance between the exhaust of by-products and the etching rate, avoid clogging of the mask, maintain the etching rate, and improve the throughput. can be made

The frequency F1 is set to be five times or more the frequency F3. More preferably, the frequency F1 is ten times or more the frequency F3. As a result, it is possible to secure the time for exhausting the by-products and suppress the clogging of the mask.

The HF pulse and the LF pulse may have a phase difference. That is, the ON time of the LF pulse and the ON time of the HF pulse may be out of sync. For example, the on-time of the LF pulse and the on-time of the HF pulse may be shifted by 100%. If the on-time of the LF pulse and the on-time of the HF pulse are 100% shifted, the on-time of the LF pulse and the on-time of the HF pulse do not overlap.

The HF pulses are, for example, powers in the range 300W to 2400W. The LF pulse has a power in the range of 500W to 7000W, for example.

The control unit 2 determines that (1) frequency F1, (2) Duty1, (3) frequency F3, (4) Duty2, and (5) frequency F1 are five times or more of frequency F3 within the ranges shown above. , to satisfy all five conditions (1) to (5). Under this condition, the plasma processing method according to this embodiment is performed.

Of the above five conditions, the power is controlled to 0 W during the off time of the HF, but the power may be controlled to be Low instead of turning off the HF. Controlling HF to Low means control to output HF with power higher than 0 W and power lower than the output level of HF output during the ON time.

Similarly, although the example in which the power is controlled to 0 W during the LF off time has been described, it may be controlled to be Low instead of turning off the LF. Controlling the LF to Low means control to output the LF with power higher than 0 W and power lower than the output level of the LF output during the ON time.

When HF is controlled to be low, radicals can be generated more than when HF is controlled to be off, so radicals can be controlled. Therefore, when it is desired to control radicals, it is better to control HF to Low than to turn HF off after turning it on. Since HF has a higher frequency than LF, ions cannot follow changes in the frequency of HF. Therefore, by controlling HF to Low, mainly radicals are controlled.

When controlling LF to Low, ions can be controlled more than when controlling LF to OFF. Since LF has a lower frequency than HF, ions can follow changes in the frequency of LF. Therefore, ions can be mainly controlled by controlling LF to Low.

As described above, according to the plasma processing apparatus and the plasma processing method according to the present embodiment, mask clogging can be avoided by providing an interval period in which LF is controlled to be off or low, and throughput can be increased. can be improved.

By adjusting various parameters in each cycle indicated by the plasma processing method according to the present embodiment, it is possible to achieve a high selectivity of the mask with respect 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 for plasma processing, the set output of HF and LF (High power, Low power), HF and LF The pulse period (frequency F1, frequency F2) and the duty ratio of HF and LF (Duty1, Duty2) can be mentioned.

The plasma processing apparatus and plasma processing method according to the embodiments disclosed this time should be considered in all respects to be illustrative and not restrictive. Embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The items described in the above multiple embodiments can take other configurations within a consistent range, and can be combined within a consistent range.

The plasma processing apparatus of the present disclosure can be applied to any type of apparatus including Atomic Layer Deposition (ALD), Capacitively Coupled Plasma (CCP), and Inductively Coupled Plasma (ICP).

1 plasma processing apparatus 2 control unit 2a computer 2a1 processing unit 2a2 storage unit 2a3 communication interface 10 plasma processing chamber 11 substrate support unit 13 shower head 21 gas source 20 gas supply unit 30 power supply 31 RF power supply 31a first RF generation unit 31b 2 RF generator 32a First DC generator 32b Second DC generator 40 Exhaust system 100 Silicon substrate 101 Etching target film 102 Mask 111 Main body 112 Ring assembly

Claims (10)

an evacuable processing container;
a first electrode arranged in the processing container and supporting the substrate to be processed;
a second electrode or antenna provided facing the first electrode;
a first high-frequency power supply unit connected to the first electrode, the second electrode, or the antenna and supplying 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 connected to the first electrode and supplying a second high-frequency power pulse for biasing to the first electrode;
a control unit that controls the first high-frequency power supply unit and the second high-frequency power supply unit,
The control unit
providing an interval period to either the first high-frequency power pulse or the second high-frequency power pulse;
setting at least one of the pulse period of the first high-frequency power pulse and the pulse period of the second high-frequency power pulse to be five times or more the period of the interval period;
Outputting the duty ratio of the first high frequency power pulse and the second high frequency power pulse at 90% or less,
controlling the substrate to be processed by plasma generated from the processing gas supplied into the processing container according to the outputs of the first high-frequency power pulse and the second high-frequency power pulse;
Plasma processing equipment. an evacuable processing container;
a first electrode arranged in the processing container and supporting the substrate to be processed;
a second electrode or antenna provided facing the first electrode;
a first high-frequency power supply unit connected to the first electrode, the second electrode, or the antenna and supplying 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 connected to the first electrode and supplying a second high-frequency power pulse for biasing to the first electrode;
a control unit that controls the first high-frequency power supply unit and the second high-frequency power supply unit,
The control unit
providing an interval period between the first high-frequency power pulse and the second high-frequency power pulse;
setting at least one of the pulse period of the first high-frequency power pulse and the pulse period of the second high-frequency power pulse to be five times or more the period of the interval period;
Outputting the duty ratio of the first high-frequency power pulse and the second high-frequency power pulse at 90% or less,
controlling the substrate to be processed by plasma generated from the processing gas supplied into the processing container according to the outputs of the first high-frequency power pulse and the second high-frequency power pulse;
Plasma processing equipment. At least one of the pulse period of the first high-frequency power pulse and the pulse period of the second high-frequency power pulse is 10 times or more the period of the interval period,
The plasma processing apparatus according to claim 1 or 2. 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 any one of claims 1-3. The duty ratio of the interval period is 10% or more and 90% or less,
The plasma processing apparatus according to any one of claims 1-4. The duty ratio of the interval period is 60% or more and 80% or less,
The plasma processing apparatus according to claim 5. The period of the interval period is 0.1 KHz or more and 1 KHz or less.
The plasma processing apparatus according to any one of claims 1-6. The pulse period of the first high-frequency power pulse and the pulse period of the second high-frequency power pulse are 1 KHz or more and 20 KHz or less,
The plasma processing apparatus according to any one of claims 1-7. The first high frequency power pulse and the second high frequency power pulse have a phase difference,
The plasma processing apparatus according to any one of claims 1-8. an evacuable processing container;
a first electrode arranged in the processing container and supporting the substrate to be processed;
a second electrode or antenna provided facing the first electrode;
a first high-frequency power supply unit connected to the first electrode, the second electrode, or the antenna and supplying 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 connected to the first electrode and supplying a second high-frequency power pulse for biasing to the first electrode;
A plasma processing method performed in a plasma processing apparatus comprising
providing an interval period to either the first high-frequency power pulse or the second high-frequency power pulse;
setting at least one of the pulse period of the first high-frequency power pulse and the pulse period of the second high-frequency power pulse to be five times or more the period of the interval period;
Outputting the duty ratio of the first high frequency power pulse and the second high frequency power pulse at 90% or less,
The substrate to be processed is processed with plasma generated from the processing gas supplied into the processing container according to the outputs of the first high frequency power pulse and the second high frequency power pulse;
Plasma treatment method.

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