JP2023006977A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

To improve the process performance.SOLUTION: A plasma processing apparatus comprises: a first electrode provided on a substrate support part; a second electrode or an antenna opposed to the first electrode; a first high-frequency power supply part connected with the first electrode, and the second electrode or the antenna, and supplying a first high-frequency power pulse; a second high-frequency power supply part connected with the first electrode, and supplying a second high-frequency power pulse; and a controller that controls the first and second high-frequency power supply parts. The controller provides the first high-frequency power pulse with first and second interval times and provides the second high-frequency power pulse with third and fourth interval times, the first high-frequency power pulse being repeatedly turned on and off during the third interval time, the second high-frequency power pulse being repeatedly turned on and off during the first interval time, the second and fourth interval times being overlapped with each other, and controls substrate processing by a plasma of a process gas depending on the outputs 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

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 plasma processing container that can be evacuated; a first electrode provided on a substrate supporting portion arranged in the plasma processing container; and a second electrode or antenna 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 first high-frequency power supply unit; a second high-frequency power supply unit connected to the first electrode and supplying a second high-frequency power pulse for biasing the first electrode; and the first high-frequency power supply unit. and a control unit that controls the second high-frequency power supply unit, wherein the control unit controls the first high-frequency power pulse to turn off the first high-frequency power pulse, the first interval time and the second providing an interval time, providing the second high-frequency power pulse with a third interval time and a fourth interval time for turning off the second high-frequency power pulse, and setting the first high-frequency power pulse on during the third interval time and off repeatedly, the second high frequency power pulse repeats on and off during the first interval time, the second interval time and the fourth interval time overlap, the first high frequency power pulse and the A plasma processing apparatus is provided for controlling a substrate to be plasma processed by plasma generated from a processing gas supplied into the plasma processing chamber in response to the output of a second high frequency power pulse.

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 plasma processing method based on a reference example. 4A and 4B are views showing an example of a plasma processing method according to the first embodiment; FIG. FIG. 4 is a diagram for explaining a plasma processing method according to a reference example; 4A and 4B are diagrams for explaining the plasma processing method according to the first embodiment; FIG. FIG. 4 is a diagram showing an example of attenuation characteristics of radicals and the like; The figure which shows an example of the plasma processing method which concerns on 2nd Embodiment. The figure which shows an example of the plasma processing method which concerns on 3rd Embodiment.

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 processing 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 support section 11 and a gas introduction section. 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, the showerhead 13 forms at least part of the ceiling of the plasma processing chamber 10 . The inside 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 upper 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 channel. 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 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 an embodiment, 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 plasma processing method according to a reference example 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.

[Plasma processing method according to reference example]
FIG. 2 is a diagram showing an example of a plasma processing method according to a reference example. In the plasma processing method according to the reference example, HF and LF are pulse waves. The duty ratio of the HF pulse is 50%. The duty ratio of the LF pulse is 20%. In the example of FIG. 2, the phases of HF and LF are shifted by 50% with respect to 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). 50% of the cycle has HF on, 20% has LF on, and 30% has both HF and LF off for a total of 100%, or one cycle. For example, the frequency of one cycle is 1 kHz and the time of one cycle is 1000 μs.

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, reaction products (reaction products) generated during etching are exhausted from recesses of the etching target film 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, high-energy ions accelerate etching, generating a large amount of reaction products that adhere to the mask. This causes clogging of the mask above the film to be etched. Mask clogging refers to narrowing of the mask opening or complete blockage of the mask opening due to reaction products adhering 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 reaction products are not efficiently discharged from the concave portion of the etching target film of the etching target.

Therefore, in the plasma processing method according to the embodiment described below, while controlling the on and off times of the HF pulse and the LF pulse, in addition to the previous off time, two further off times are controlled, and a total of RF control with three Off Times is performed. This makes it possible to achieve both avoidance of mask clogging and high mask selectivity. A plasma processing method according to an embodiment will be described below.

[Plasma processing method according to the embodiment]
(First embodiment)
A plasma processing method according to the first embodiment will be described with reference to FIG. FIG. 3 is a diagram showing an example of the plasma processing method according to the first embodiment. In the plasma processing method according to the embodiment, as shown in FIG. 3, the pulse period of the HF pulse is indicated by the frequency F1, the pulse period of the LF pulse is indicated by the frequency F2, and the HF pulse and the LF pulse are turned on at each pulse period. and off cycles are controlled.

In the example of FIG. 3, the pulse period of the HF pulse indicated by frequency F1 and the pulse period of the LF pulse indicated by frequency F2 are each 10 kHz. However, not limited to this, the pulse period of the HF pulse and the pulse period of the LF pulse may each be in the range of 10 kHz to 20 kHz, and may be the same as in the present disclosure, or may be different.

Duty1 (first duty ratio) of the HF pulse indicates the ON time of HF with respect to the total time of ON time and OFF time of HF. In the example of FIG. 3, Duty1 is 75%, and the HF pulse periodically repeats HF on and off so that 3/4 of one cycle is on and 1/4 is off. The time during which the HF is repeatedly turned on and off in this manner is also referred to as the "output time of the HF pulse". In the example of FIG. 3, the 1st to 5th cycles are the HF pulse output time.

The HF pulse has a first interval time and a second interval time for turning off the HF. The 6th to 7th cycles are the first interval time ((1) in FIG. 3), and the 8th to 10th cycles are the second interval time (2). The first interval time (1) and the second interval time (2) may be continuous or discontinuous.

The LF pulse Duty2 (second duty ratio) indicates the LF ON time with respect to the total time of the LF ON time and OFF time. In the example of FIG. 3, Duty2 is 50%, and the LF pulse periodically repeats LF on and off so that 1/2 of one cycle is on and 1/2 is off. The time during which the LF is repeatedly turned on and off in this way is also referred to as the "LF pulse output time". In the example of FIG. 3, the 6th and 7th cycles are the LF pulse output time.

The LF pulse has a third interval time and a fourth interval time for turning off the LF. The 1st to 5th cycles are the third interval time ((3)), and the 8th to 10th cycles are the fourth interval time (4). The third interval time (3) and the fourth interval time (4) may be continuous or discontinuous.

The output time of the HF pulse and the output time of the LF pulse do not overlap. The HF pulse output time and the third interval time (3) overlap, and the LF pulse output time and the first interval time (1) overlap. In the present disclosure, the output time of the HF pulse is followed by the output time of the LF pulse, followed by an interval time during which both the HF pulse and the LF pulse are turned off, but this is not the only option. For example, the output time of the LF pulse may be followed by the output time of the HF pulse, followed by an interval time during which both the HF pulse and the LF pulse are turned off. For example, after the output time of the LF pulse, there may be an interval time during which both the HF pulse and the LF pulse are turned off, followed by the output time of the HF pulse.

In the present disclosure, the output time of the HF pulse and the output time of the LF pulse are completely shifted, and the on timing of the HF pulse and the on timing of the LF pulse do not overlap. However, the output time of the HF pulse and the output time of the LF pulse may partially overlap. In the present disclosure, the third interval time (3) and the HF pulse output time completely overlap, but they may partially overlap. In the present disclosure, the first interval time (1) and the LF pulse output time completely overlap, but they may partially overlap. The first interval time (1) and the third interval time (3) do not overlap. The second interval time (2) and the fourth interval time (4) overlap.

The interval period in which the second interval time (2) and the fourth interval time (4) overlap is indicated by frequency F3. The frequency F3 is a period in which the interval time in which the second interval time (2) and the fourth interval time (4) overlap appears repeatedly, and is 1 kHz in the example of FIG. It may be 2 kHz. The interval period indicated by frequency F3 is longer in cycle than the pulse periods of HF and LF indicated by frequencies F1 and F2. In the example of FIG. 3, frequency F1 and frequency F2 are ten times frequency F3. Frequency F1 and frequency F2 may be ten times or more of frequency F3.

Duty3 is the time to repeat the on and off of the HF pulse indicated by Duty1 (output time of the HF pulse), the time to repeat the on and off of the LF pulse indicated by Duty2 (output time of the LF pulse), the HF pulse and the LF pulse are both turned off and the total output time of the HF and LF pulses with respect to the total time (1000 μs in the example of FIG. 3). In the example of FIG. 3, Duty3 is 70% (HF pulse output time is 50%, LF pulse output time is 20%), but not limited to this, Duty3 may be 10%-90%.

Each off-time of the HF pulse within the output time of the HF pulse is shorter than the first interval time (1) and the second interval time (2). Each of the off times of the LF pulse within the output time of the LF pulse is shorter than the third interval time (3) and the fourth interval time (4).

During cycles 1 to 5, the HF pulse is turned on and off 5 times, during which the LF is controlled to be off in the third interval time (3). During the 6-7 cycles, the LF pulse is turned on and off twice, during which the HF is controlled to be off for the first interval time (1). During 8-10 cycles, the second interval time (2) and the fourth interval time (4) in which both the HF and LF pulses are controlled off. In the example of FIG. 3, the interval time at which both HF and LF are turned off is set to 30%, but the interval time indicated by the second interval time (2) and the fourth interval time (4) is 10%. % or more and 90% or less.

The control unit 2 controls the first RF generation unit 31a and the second RF generation unit 31a to process the substrate W with 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. 2 RF generator 31b. As a result, it is possible to achieve both avoidance of clogging of the mask and improvement of the high selectivity of the mask. The reason for this will be described with reference to the reference example of FIG. 4 and the drawings relating to the embodiment of FIGS.

FIG. 4 is a diagram for explaining a plasma processing method according to a reference example. FIG. 5 is a diagram for explaining the plasma processing method according to the first embodiment. FIG. 6 is a diagram showing an example of attenuation characteristics of radicals and the like. In the reference example and the present embodiment, for example, a SiO ₂ film is formed as an etching target film 101 on a substrate, and a mask 102 such as an organic film is formed thereon. The etching target film 101 is etched according to the pattern of the mask 102 to form recesses (holes or the like) corresponding to the pattern in the etching target film 101 . However, the film structure on the substrate W is not limited to this.

In the plasma processing method according to the reference example shown in FIG. 4, there is an interval time during which the HF pulse and LF pulse are turned off during 8 to 10 cycles. Between 1 and 7 cycles, the pulse period of the HF and LF pulses is 1 kHz in the example of FIG. Both the duty ratio of the HF pulse and the duty ratio of the LF pulse are 50%. There is a phase difference between HF and LF, and LF is turned on at the timing when HF is turned off.

The interval period is 0.1 kHz, which is longer than the pulse periods of the HF and LF pulses. The pulse period of the HF and LF pulses is ten times the interval period.

The interval cycle is set to 30% of the total time of the HF pulse and LF pulse repeating on and off (total cycle time of 1 to 7 cycles) and the interval time in which HF and LF are continuously off. there is

In period A of the first cycle shown in FIG. 4, the HF pulse is controlled to be ON and the LF pulse is controlled to be OFF. Therefore, in period A, as shown in FIG. 4A, HF contributes to the generation of plasma and radicals, ions, electrons, and radicals are generated, and high-density plasma is generated.

In period B of the first cycle shown in FIG. 4, the LF pulse is controlled to be ON and the HF pulse is controlled to be OFF. Therefore, during the B period, the LF draws high-energy ions into the concave portion of the etching target film 101 . As a result, during the B period, ions having high energy promote etching. In addition, since high-density plasma is generated in period A, the number of ions in the high-density plasma is large and ion energy is high in period B, so etching is promoted, and the amount of reaction products is relatively large. Become.

When reaction products generated during etching adhere to the side surfaces and top surface of the mask 102 to form a protective film, the selectivity of the mask 102 can be improved. However, since the high-density plasma is generated in the period A, the number of ions in the high-density plasma is large in the subsequent period B, so ions with various incident angles are generated, and the ion incident angle distribution is large. . Therefore, as shown in FIG. 4B, ions with various angles of incidence enter the recesses of the film 101 to be etched, and therefore, are likely to collide with reaction products in the recesses. This collision inhibits the evacuation of the reaction products, making it difficult for the reaction products to be discharged from the recesses of the etching target film 101. As a result, the reaction products adhere to the side and top surfaces of the mask 102, forming a protective film. is also hindered, and the mask selection ratio is not improved.

The above phenomenon is repeated in periods A and B in the second to seventh cycles shown in FIG. Since both the HF pulse and the LF pulse are controlled to be off during the interval time of the 8th to 10th cycles, as shown in FIG. be done.

As described above, in the case of the plasma processing method according to the reference example shown in FIG. 4, the ions in the high-density plasma generated in the period A inhibit the exhaust of the reaction product during the period B, and the reaction product is masked. It is difficult to adhere to the side or top surface of the This makes it difficult to improve the high selectivity of the mask.

On the other hand, in the plasma processing method according to the present embodiment, as shown in FIG. 5, the times during which both the HF pulse and the LF pulse are turned off are "Off time 1," "Off time 2," and "Off time 3." is provided. The interval times of Off time1 and Off time2 are shorter than the interval time of Off time3.

In period C of the first cycle shown in FIG. 5, the HF pulse is controlled to be ON and the LF pulse is controlled to be OFF. Therefore, in period C, as shown in FIG. 5A, HF contributes to the generation of plasma and radicals, ions, electrons, and radicals are generated, and high-density plasma is generated.

In the D period of the first cycle, both the HF pulse and the LF pulse are turned off for a short period of time, eg, 10 to 100 μs. FIG. 6 shows attenuation characteristics of electrons, ions and radicals. The horizontal axis in FIG. 6 is time, and the vertical axis is normalized attenuation. When the RF power (HF) is switched from on to off, the electron temperature (Plasma Potential) first decays sharply. Next, the ions (Plasma Density) are attenuated. In contrast, decay of radicals is moderate.

As a result, in this embodiment, even if HF is turned off during period D, the plasma density can be maintained at a moderate level without deactivating the radicals necessary for etching. In the 1st to 5th cycles, the HF pulse is periodically turned on and off in this way, and the HF is turned on intermittently, so that the plasma density is moderately controlled without increasing the density. In the 1st to 5th cycles, the LF pulse is the third interval time (3) controlled to be off.

In the case of high-density plasma, since the number of ions in the plasma is large, ions with various angles of incidence are generated and the distribution of the angles of incidence of ions is large. On the other hand, by providing Off time 1 in the output time of the HF pulse and controlling the plasma density to an intermediate level as in the present embodiment, the number of ions in the plasma can be reduced more than in the case of high-density plasma. As a result, the distribution of incident angles of ions can be reduced. In other words, it is possible to generate ions having relatively uniform incident angles. As a result, as shown in FIG. 5B, the angles of the ions incident on the etching target film 101 are aligned in the vertical direction to some extent, and the ions can be given directivity.

As shown in FIG. 5(c), collisions between reaction products generated during etching and ions used in the next etching are reduced by the directivity of ion incidence with little variation in the angle of incidence of ions. be able to. In the 6th and 7th cycles, the LF pulse is turned on in the E period to attract ions, and the action of undeactivated radicals is added to promote etching. The accelerated etching also increases the amount of reaction products produced at time E. FIG. Therefore, in the following time F, a short time of 10 to 100 μs, for example, Off time 2 is provided in the output time of the LF pulse to promote the evacuation of reaction products. As the evacuation of reaction products during etching is accelerated, the amount of reaction products adhering to the side and top surfaces of the mask 102 increases. Thereby, the mask selection ratio can be improved. During this period, the HF pulse is the first interval time (1) and is controlled to be off.

If there is no Off time 2, the LF pulse continues to be turned on in the 6th and 7th cycles, and etching progresses due to ion attraction. Therefore, although the amount of reaction products produced increases, exhaust is not promoted. When there is Off time 2, etching progresses due to the attraction of ions and the action of radicals while the LF pulse is turned on, and while the LF pulse is turned off, the evacuation of reaction products is promoted and the mask selectivity is improved. be able to. In this way, as shown in FIG. 5(c), by alternately providing an E period during which the LF pulse is turned on and an F period during which the LF pulse is turned off, the etching is accelerated, the evacuation of reaction products is accelerated, and mask selection is performed. ratio can be improved.

Off time 3 is the second interval time (2) of the HF pulse and the fourth interval time (4) of the LF pulse, and both the HF pulse and the LF pulse are controlled to be off. During the 8th to 10th cycles, the evacuation of reaction products is sufficiently promoted as shown in FIG. 5(d). As a result, the reaction product adheres to the mask 102 while being exhausted from the concave portion formed in the etching target film 101, and the mask selectivity can be improved.

As described above, Off time 1 is provided in the plasma processing method according to the present embodiment. Thereby, the plasma density can be moderately controlled during the D period in which the HF pulse is turned off.

In addition, by providing Off time 2, the collision between the reaction product generated during etching and the ions used in the next etching during the E period during which the LF pulse is turned on is reduced, the etching is accelerated, and the LF pulse is turned off during the F period. Since collisions with ions are reduced, it is possible to accelerate the evacuation of reaction products and improve the mask selectivity. By repeating this alternately, it is possible to improve the evacuation and the mask selectivity during etching. In addition, by providing Off time 3, the exhaust of the reaction product can be sufficiently accelerated. Accordingly, in the plasma processing method according to the present embodiment, it is possible to achieve both avoidance of clogging of the mask and high selectivity of the mask. Thereby, the performance of the process performed in the plasma processing apparatus can be improved.

The above is an example, and in the plasma processing method according to the first embodiment, the HF pulse is periodically turned on and off in the 1st to 5th cycles, and the LF pulse is turned on and off in the 6th to 7th cycles. Although it repeats periodically, the cycle in which the HF pulse and the LF pulse are repeated is not limited to this.

(Second embodiment)
A plasma processing method according to the second embodiment will be described with reference to FIG. FIG. 7 is a diagram showing an example of a plasma processing method according to the second embodiment. The difference between the plasma processing method according to the second embodiment and the plasma processing method according to the first embodiment is that the HF pulse has two pulse periods of 20 kHz and 10 kHz, and the duty ratio is different. Also, the pulse period of the LF pulse is the same, but the duty ratio is different. Other conditions are the same.

In the HF pulse output time of the 1st to 5th cycles, the pulse period is 10 kHz and the duty ratio is 75% in the 1st, 3rd and 5th cycles. The second and fourth cycles have a pulse period of 20 kHz and a duty ratio of 80%. As a result, Off time 1 occurs once per cycle in the 1st, 3rd and 5th cycles, and Off time 1 occurs twice per cycle in the 2nd and 4th cycles.

In the LF pulse output time of the 6th to 7th cycles, the pulse period is 10 kHz in all of the 6th to 7th cycles, the duty ratio is 75% in the 6th cycle, and the duty ratio is 50% in the 7th cycle. be. As a result, Off time 2 occurs once per cycle in the 6th and 7th cycles.

The above is only an example, and in the plasma processing method according to the second embodiment, either the frequency of the pulse cycle of the HF pulse or the duty ratio may be the same. Also, the pulse period of the LF pulse may be different. At least one of the HF pulse and the LF pulse may have three or more frequencies and duty ratios.

(Third Embodiment)
A plasma processing method according to the third embodiment will be described with reference to FIG. FIG. 8 is a diagram showing an example of a plasma processing method according to the third embodiment. The plasma processing method according to the third embodiment differs from the plasma processing method according to the first embodiment in that there are two types of HF pulse amplitudes and two types of LF pulse amplitudes. Other conditions are the same.

In the HF pulse output time of the 1st to 5th cycles, the amplitude of the 1st, 3rd and 5th cycles is A1, and the amplitude of the 2nd and 4th cycles is A2. In the output time of the LF pulse in the 6th and 7th cycles, the amplitude is B1 at the 6th cycle and B2 at the 7th cycle.

The above is an example, and the output time of each HF pulse and LF pulse may be controlled by changing at least one of the pulse period, duty, and amplitude for each cycle. At least one of the HF pulse and the LF pulse may have three or more amplitudes.

(others)
Duty1 is set to 90% or less. This is because setting Duty1 to 90% or more increases the possibility of clogging of the mask and inhibits the promotion of the evacuation of reaction 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 plasma may not be ignited.

Duty2 is preferably 10% or more and 90% or less. This is because when Duty2 is set to less than 10%, the time during which LF is turned on is shortened, and the reaction products are better exhausted from the recesses 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 discharge of reaction products from the concave portions of the etching target film 101 becomes poor, causing clogging of the mask (mask clogging) and etch stop. This is because it is possible.

As described above, according to the plasma processing apparatus and the plasma processing method of the present embodiment, it is possible to achieve both avoidance of mask clogging and high mask selectivity. Thereby, the performance of the process performed in the plasma processing apparatus can be improved.

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 (11)

an evacuable plasma processing vessel;
a first electrode provided on a substrate supporting portion arranged in the plasma processing container;
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 the first high-frequency power pulse with a first interval time and a second interval time for turning off the first high-frequency power pulse;
providing the second high-frequency power pulse with a third interval time and a fourth interval time for turning off the second high-frequency power pulse;
the first high-frequency power pulse is repeatedly turned on and off during the third interval time;
the second high-frequency power pulse is repeatedly turned on and off during the first interval time;
the second interval time and the fourth interval time overlap,
controlling the substrate to be plasma-processed by plasma generated from the processing gas supplied into the plasma processing container according to the outputs of the first high-frequency power pulse and the second high-frequency power pulse;
Plasma processing equipment. The first duty ratio of the first high-frequency power pulse and the second duty ratio of the second high-frequency power pulse are each 10% or more and 90% or less.
The plasma processing apparatus according to claim 1. A third duty ratio of the second interval time and the fourth interval time is 10% or more and 90% or less.
The plasma processing apparatus according to claim 1 or 2. The period of the first high-frequency power pulse and the period of the second high-frequency power pulse are each 10 times or more the period of the second interval time or the fourth interval time,
The plasma processing apparatus according to any one of claims 1-3. The cycle of the second interval time and the fourth interval time is 1 kHz or more and 2 kHz or less.
The plasma processing apparatus according to any one of claims 1-4. The period of the first high-frequency power pulse and the period of the second high-frequency power pulse are each 10 kHz or more and 20 kHz or less,
The plasma processing apparatus according to any one of claims 1-5. The period of the first high frequency power pulse and the period of the second high frequency power pulse are the same.
The plasma processing apparatus according to any one of claims 1-6. Duty ratios of the first high-frequency power pulse and the second high-frequency power pulse are the same,
The plasma processing apparatus according to any one of claims 1-7. the first interval time and the third interval time do not overlap;
The plasma processing apparatus according to any one of claims 1-8. the amplitude of at least one of the first RF power pulse or the second RF power pulse has a plurality of power or voltage levels;
The plasma processing apparatus according to any one of claims 1-9. an evacuable plasma processing vessel;
a first electrode provided on a substrate supporting portion arranged in the plasma processing container;
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 the first high-frequency power pulse with a first interval time and a second interval time for turning off the first high-frequency power pulse;
providing the second high-frequency power pulse with a third interval time and a fourth interval time for turning off the second high-frequency power pulse;
the first high-frequency power pulse is repeatedly turned on and off during the third interval time;
the second high-frequency power pulse is repeatedly turned on and off during the first interval time;
the second interval time and the fourth interval time overlap,
Plasma processing a substrate with plasma generated from a processing gas supplied into the plasma processing chamber 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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