Plasma processing apparatus and plasma processing method

Abstract

To improve performance of a process.SOLUTION: A plasma processing apparatus comprises: a first electrode that supports a substrate; a second electrode or an antenna that faces the first electrode; a first high-frequency power supplying unit that is connected to the first electrode, the second electrode or the antenna, and supplies first high-frequency power for generating plasma to the first electrode, the second electrode or the antenna; a second high-frequency power supplying unit that is connected to the first electrode, and supplies second high-frequency power for a bias to the first electrode; and a control unit that controls the first high-frequency power supplying unit and the second high-frequency power supplying unit, the control unit performing control to sequentially and repetitively output first high-frequency power of a first level and first high-frequency power of a second level, to output second high-frequency power of a third level in a first period before the first high-frequency power of the first level is output after the first high-frequency power of the second level is output, and to process the substrate by plasma generated from a processed gas according to the output of the first high-frequency power and the second high-frequency power.SELECTED DRAWING: Figure 4

Description

[Technical field]

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

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

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

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

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

[0006] According to one aspect of the present disclosure, there is provided a processing vessel that can be evacuated to a vacuum, a first electrode that is disposed in the processing vessel and that supports a substrate to be processed, a second electrode or an antenna that faces the first electrode, a first high frequency power supply unit that is connected to the first electrode, the second electrode, or the antenna and that supplies a first high frequency power for plasma generation to the first electrode, the second electrode, or the antenna, a second high frequency power supply unit that is connected to the first electrode and that supplies a second high frequency power for bias to the first electrode, and a controller that controls the first high frequency power supply unit and the second high frequency power supply unit, the first high frequency power supply unit outputs the first high frequency power of a first level and the first high frequency power of a second level in sequence and repeatedly outputs the second high frequency power of a third level from the second high frequency power supply unit during a first period after the first high frequency power supply unit outputs the first high frequency power of the second level and before the first high frequency power of the first level is output; and in response to the outputs of the first high frequency power and the second high frequency power, a substrate to be processed is processed by plasma generated from a processing gas supplied into the processing vessel. Effect of the Invention

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

[0008] [Figure 1] 1 is a schematic cross-sectional view illustrating an example of a plasma processing system according to an embodiment. [Diagram 2] FIG. 1 is a diagram showing an example of a conventional plasma processing method. [Diagram 3] 1A to 1C are views showing an example of a plasma processing method according to a first embodiment. [Figure 4] 1A to 1C are views showing an example of a plasma processing method according to a first embodiment. [Diagram 5] FIG. 1 is a diagram for explaining the decay of radicals and the like. [Figure 6]10A to 10C are views showing an example of a plasma processing method according to a second embodiment. [Figure 7] 11A to 11C are views showing an example of a plasma processing method according to a third embodiment. [Figure 8] 13A to 13C are views showing an example of a plasma processing method according to a fourth embodiment. [Figure 9] 13A to 13C are views showing an example of a plasma processing method according to a fifth embodiment. [Figure 10] 13A to 13C are views showing an example of a plasma processing method according to a sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

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

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

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

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

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

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

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

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

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

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

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

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

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

[0022] [Conventional plasma processing method] 2(a) and (b) are diagrams showing an example of a conventional plasma processing method. In the conventional plasma processing method, in the example of FIG. 2(a), HF is a continuous wave, and LF is a pulse wave (LF pulse). In the example of FIG. 2(b), HF and LF are pulse waves (HF pulse, LF pulse).

[0023] In the example of Fig. 2(a), the LF pulse is repeatedly turned on intermittently while the HF is turned on (supplied).In the example of Fig. 2(b), the LF pulse is turned on a predetermined period after the HF pulse is turned on, and the HF pulse is repeatedly turned on at the same timing as the LF pulse is turned off.

[0024] While the HF is on, plasma and radicals are generated. While the LF is on, ions in the plasma are attracted to the substrate, accelerating the etching. While the HF and LF are off, by-products (reaction products) generated during etching are exhausted from recesses formed in the film to be etched.

[0025] In order to achieve high anisotropic etching, i.e., verticality of the etching profile, while maintaining a high etching rate, a high-output LF power is required. However, in the example of FIG. 2, while the LF is on, high-output LF power is applied, and while the etching target film on the substrate is etched by high-energy ions, the mask is also etched by the high-energy ions. In addition, a large amount of by-products adhere to the mask as the etching is accelerated by the high-energy ions. This causes clogging of the mask on the etching target film. Mask clogging refers to the narrowing of the mask opening or the complete blockage of the mask opening due to by-products adhering to the sidewall of the mask. As a method for avoiding mask clogging, there is a method of turning off both the HF and LF before applying HF and providing a time (Off Time) to accelerate exhaust.

[0026] Therefore, in the plasma processing methods according to the first to sixth embodiments described below, both HF and LF are turned off before HF is applied, and a time (Off Time) is provided to promote exhaust. This makes it possible to maintain the etching rate while avoiding mask clogging.

[0027] First Embodiment [Plasma treatment method] First, the plasma processing method according to the first embodiment will be described with reference to Fig. 3 to Fig. 5. Fig. 3 and Fig. 4 are diagrams illustrating an example of the plasma processing method according to the first embodiment. Fig. 5 is a diagram for explaining the decay of radicals and the like.

[0028] In the plasma processing methods according to the first to sixth embodiments, as shown in FIG. 3 and other figures, HF and LF are output as pulse waves, that is, HF pulses and LF pulses.

[0029] 3, for example, HF has a frequency of, for example, 100 MHz and is a pulse wave (HF pulse) that repeats on and off. LF has a frequency of, for example, 13.56 MHz and is a pulse wave (LF pulse) that repeats on and off.

[0030] In the example of Figure 3, the duty ratio of the HF pulse is 20%. The duty ratio of the LF pulse is 25%. In the example of Figure 3, the HF and LF are controlled to be out of phase with each other, and the on-time (supply time, application time) of the HF and LF do not overlap. Immediately after the HF is turned off (supply is stopped), there is a period during which the HF and LF are off (OFF time: 25% of one cycle), and then the LF is turned on.

[0031] The duty ratio of the LF pulse is 25%. After the LF is turned on, there is a period during which the HF and LF are turned off again (OFF time: 30% of one cycle), and then the HF is turned on in the next cycle.

[0032] For the first 20% of one cycle, HF is on and LF is off (first step). For the next 25%, HF and LF are off (second step). For the next 25%, HF is off and LF is on (third step). For the next 30%, HF and LF are off (fourth step). This makes the total of each step in one cycle 100%. In the example of Figure 3, the phases of the HF pulse and LF pulse are controlled to be shifted. The OFF time of the fourth step is necessary to promote exhaust. The OFF time of the second step is preferably provided to control the ratio of radicals and ions in the plasma. After the first cycle, the same operation is repeated for the second cycle, third cycle, etc.

[0033] Specifically, as shown in Fig. 4, in period A in which the first step is executed, HF is turned on and LF is turned off. Therefore, in period A, HF contributes to the generation of plasma and radicals, and ions, electrons, and radicals are generated, as shown in Fig. 4(a).

[0034] Note that the LF may be controlled to Low instead of being turned off during periods A, B, and D1. Controlling the LF to Low refers to control to output an LF with a power higher than 0 W and lower than the output level of the LF output during the on time.

[0035] When LF is controlled to low, ions can be controlled more effectively than when LF is controlled to off. Ions cannot follow HF. On the other hand, LF has a lower frequency than HF, so ions can follow changes in the LF frequency. Therefore, by controlling LF to low, ions can be mainly controlled.

[0036] In the following period B in which the second step is performed, HF is turned off and LF is also turned off. In period B, the amount of radicals and ions can be controlled. FIG. 5, an enlarged view of the graph in FIG. 4(b), shows the decay of radicals, ions and electrons. The horizontal axis of FIG. 5 is time and the vertical axis is the normalized decay amount. When the HF power is switched from on (Power ON) to off (Power OFF), the electrons (Plasma Potential) decay rapidly first. Next, the positive ions (Plasma Density) decay. In contrast, the decay of radicals is gradual.

[0037] Thus, since electrons and ions decay relatively quickly while radicals decay relatively slowly, the ratio of radicals to cations increases and the ion energy decreases during period B, making it possible to control the amount of radicals and ions.

[0038] 4, instead of turning off the HF, the HF may be controlled to Low during period B and the following periods C and D1. Controlling the HF to Low means outputting the HF at a power higher than 0 W and lower than the output level of the HF output during the ON time.

[0039] When HF is controlled to low, more radicals can be generated than when HF is controlled to off, so radicals can be controlled. Therefore, when radical control is desired, it is better to control HF to low than to turn it on and then off. Ions cannot follow the changes in HF, which has a higher frequency than LF. For this reason, by controlling HF to low, radicals can be mainly controlled.

[0040] In the following period C in which the third step is executed, the HF is turned off and the LF is turned on. During this period, as shown in Fig. 4(c), the LF draws high-energy ions into the recesses of the film 101 to be etched. As a result, the ions in the plasma are drawn into the substrate, and the etching is mainly promoted by the ions with high energy. Also, since the plasma density decreases during period B mainly due to the attenuation of electrons, ions, and radicals, when the LF is turned on during period C, the ions with high energy are smoothly drawn in, and etching can be promoted.

[0041] In period C, the ion energy is high and the etching rate is fast, so the ion incident angle is relatively narrow and etching tends to proceed vertically, but damage to the mask 102 tends to be large.

[0042] In the subsequent period D1 in which the fourth step is executed, HF and LF are also turned off. During this period, by-products generated during etching in period C are exhausted from the recesses formed in the film 101 to be etched, as shown in FIG. 4(d). This allows ions and the like that have accumulated at the bottom of the recesses to be exhausted, and charge cancellation is performed. In addition, as shown in FIG. 4(e), ions with low energy etch the top and sides of the mask 102, thereby removing by-products that have adhered to the sides of the mask 102. This suppresses clogging.

[0043] According to the plasma processing method of the first embodiment, the first RF generating unit 31a outputs HF power at a first level during period A, and HF power at a second level is output in sequence and repeatedly during periods B to D1. After the first RF generating unit 31a outputs HF power at the second level, the second DC generating unit 32b outputs LF power at a third level during a first period before the HF power at the first level is output during the next period A. By this control, the substrate W is processed by plasma generated from the processing gas supplied into the plasma processing chamber 10 according to the output of the HF and LF powers. The period D1 shown in FIG. 4 is an example of the first period.

[0044] Moreover, in the plasma processing method according to the first embodiment, there is a second period from when the HF power of the second level is output until when the LF power of the third level is output. Period B shown in FIG. 4 is an example of the second period. By providing periods during which both HF and LF are controlled to be off or low in period B and period D1, it is possible to control radicals and ions and promote exhaust. Period B in each embodiment described below is an example of the second period.

[0045] In addition, in Fig. 4, the period A in which the HF of the first level is controlled to be on is shown as the first control of one cycle, but this is not limited to this, and the period C in which the LF of the third level is controlled to be on may be the first control of one cycle. The other periods B and D1 may also be the first control of one cycle. Similarly, in each of the following embodiments, the HF and LF are not limited to being controlled in order from the period A. For example, after plasma ignition, depending on the process conditions, the HF and LF may be controlled periodically, starting from the control of LF on in period C, such as C → D1 → A → B → C...

[0046] <Second embodiment> [Plasma treatment method] Next, a plasma processing method according to a second embodiment will be described with reference to Fig. 6. Fig. 6 is a diagram showing an example of the plasma processing method according to the second embodiment.

[0047] The plasma processing method according to the second embodiment differs from the plasma processing method according to the first embodiment in that it has periods E and F in addition to periods A to D2. In other words, the control of HF and LF during periods A to D2 in the plasma processing method according to the second embodiment and the effects shown in Figures 6(a) to 6(e) are the same as the control of HF and LF during periods A to D1 in the plasma processing method according to the first embodiment and the effects shown in Figures 4(a) to 4(e).

[0048] 6, HF is turned on and LF is turned off during period A. Therefore, during period A, HF contributes to the generation of plasma and radicals, and ions, electrons, and radicals are generated, as shown in FIG.

[0049] In the following period B, HF is turned off and LF is turned off. In period B, as shown in Fig. 5 and Fig. 6(b), electrons and ions decay relatively quickly while radicals decay relatively slowly, so that in period B, the ratio of radicals to ions increases due to the difference in decay speed, and the amount of radicals and ions can be controlled.

[0050] In the following period C, the HF is turned off and the LF is turned on. During this period, as shown in Fig. 6(c), the LF draws high-energy ions into the recesses of the film 101 to be etched. As a result, the ions in the plasma are drawn into the substrate, and the etching is mainly promoted by the high-energy ions. Also, since the plasma density decreases during period B mainly due to the attenuation of electrons, ions, and radicals, when the LF is turned on during period C, the high-energy ions are smoothly drawn in and etching is promoted.

[0051] In the following period F, the HF is turned on to a middle level, which is lower than the output level in period A and higher than the output level in period C, and the LF is turned on. During this period, plasma and radicals with a lower density than the plasma density shown in FIG. 6(a) are generated, and the high-energy ions therein are drawn into the recesses in the film 101 to be etched by the LF, as shown in FIG. 6(f). As a result, the ions in the plasma are drawn into the substrate, and the etching is mainly promoted by the ions with high energy. In addition, by-products generated during etching adhere to the side walls of the recesses formed in the film 101 to be etched and to the sides and top of the mask 102. In addition, O 2 supplied as a sidewall protection gas is also generated. 2 The gas is dissociated by HF and O 2 The radicals are attached to the sidewalls of the recesses and to the sides and top of the mask 102. As a result, in period F, a protective film 105 is formed on the sidewalls of the recesses formed in the etching target film 101. Note that, since HF is turned off in period C, O 2 supplied as a sidewall protective gas is not used. 2 Dissociation of the gas does not proceed, and the protective film 105 is unlikely to be formed on the side walls of the recess formed in the etching target film 101 .

[0052] In the following E period, HF is turned on to the middle level as in F period, and LF is turned off. During this period, HF generates plasma and radicals with a lower density than that at high power due to the middle level power. As a result, as shown in FIG. 6(e), ions with weak energy etch the top and sides of the mask 102, removing by-products attached to the sides of the mask. This prevents mask clogging.

[0053] In the following period D2, HF is turned off and LF is also turned off. During this period, by-products generated during etching are exhausted from recesses formed in the etching target film 101, as shown in Fig. 6(d). Period D2 is an example of a third period in which HF power of the second level is outputted after HF power of the fourth level is outputted and before HF power of the first level is outputted.

[0054] In the plasma processing method according to the second embodiment, HF power of a first level is output in period A, HF power of a second level is output in periods B, C, and D2, and HF power of a fourth level is output in periods F and E, and this is repeated in sequence. After HF power of the second level is output, LF power of a third level is output in a third period (period D2) before HF power of the first level is output in the next period A. According to the plasma processing method according to the second embodiment, LF power of a level higher than the third level is output in period C, and then HF power of the fourth level is output in periods F and E.

[0055] In the plasma processing method according to the second embodiment, similarly to the plasma processing method according to the first embodiment, periods in which both HF and LF are controlled to be off or low are provided before and after period A in which the first level HF is on. This makes it possible to control radicals and ions and promote exhaust. In this embodiment, HF and LF are off in periods B and D2. Period D2 is an example of a third period before period A, and period B is an example of a second period after period A.

[0056] Furthermore, in the plasma processing method according to the second embodiment, in periods F and E, HF is controlled to a middle level that is lower than the output level in period A and higher than the output level in period B, etc. LF is turned on in period F and turned off in period E.

[0057] As a result, by-products generated during etching in period C adhere to the side walls of the recesses in the etching target film 101 and the sides and upper part of the mask 102 in period F, thereby suppressing bowing and damage to the mask. In period E, ions with low energy etch the upper part and sides of the mask 102, thereby removing the by-products adhered to the sides of the mask and suppressing clogging.

[0058] <Third embodiment> [Plasma treatment method] Next, a plasma processing method according to a third embodiment will be described with reference to Fig. 7. Fig. 7 is a diagram showing an example of the plasma processing method according to the third embodiment.

[0059] The plasma processing method according to the third embodiment has a period G between the periods C and D3, which is different from the plasma processing method according to the first embodiment which does not have period G as shown in Fig. 4. That is, the control of HF and LF during the periods A to D3 in the plasma processing method according to the third embodiment and the effects shown in Figs. 7(a) to (d) are the same as the control of HF and LF during the periods A to D1 in the plasma processing method according to the first embodiment and the effects shown in Figs. 4(a) to (e).

[0060] In period A in Fig. 7, HF is turned on and LF is turned off. During this period, HF contributes to the generation of plasma and radicals, similar to the effect of period A shown in Fig. 4(a), and ions, electrons, and radicals are generated.

[0061] In the following period B, HF is turned off and LF is turned off. In period B, the ratio of radicals to ions increases due to the difference in the decay speed of electrons, ions, and radicals, similar to the effect of period B shown in Fig. 4(b), and as a result, the amount of radicals and ions can be controlled.

[0062] In the following period C, the HF is turned off and the LF is turned on. During this period, the LF draws high-energy ions into the recesses of the film 101 to be etched, similar to the effect of period C shown in FIG. 4(c), and mainly promotes etching.

[0063] In the following G period, the LF is turned on to a middle level that is smaller than the output level in the C period and larger than the output level in the D3 period, and the HF is turned off. During this period, as an effect of FIG. 7(g), although not shown, the energy of the ions drawn into the recesses of the etching target film 101 can be controlled by the difference in the power level of the LF. This changes the energy when the ions are drawn into the substrate, and the etching rate is controlled. For example, in the G period, the power of the LF is smaller than that in the C period, so the energy of the ions drawn into the recesses is also smaller, and the etching rate decreases, but the damage to the mask 102 is reduced. In addition, the amount of by-products generated during etching that adhere to the sidewalls of the recesses formed in the etching target film 101 and the sides and top of the mask 102 is controlled. The middle level LF output in the G period is an example of the LF power of the fifth level.

[0064] In the following period D3, LF and HF are turned off. During this period, as shown in FIG. 4(d), by-products generated during etching are exhausted from the recesses formed in the film 101 to be etched. Also, as shown in FIG. 4(e), ions with low energy etch the top and sides of the mask 102, thereby removing by-products attached to the sides of the mask 102. This suppresses clogging.

[0065] The D3 period is an example of a fourth period in which LF power at the fifth level is output in the G period, and then HF power at the second level is output before HF power at the first level is output.

[0066] In the plasma processing method according to the third embodiment, HF power of a first level is output in period A, and HF power of a second level is output in periods B, C, G, and D3, and this is repeated in sequence. After HF power of the second level is output, LF power of a third level is output in a fourth period (period D3) before HF power of the first level is output in the next period A. LF power of a fifth level is output in period G immediately preceding the fourth period. In this embodiment, control is performed so that LF power of the third level is further output during the period G after LF power of the fifth level is output and before HF power of the first level is output.

[0067] According to the plasma processing method of the third embodiment, similarly to the plasma processing method of the first embodiment, periods in which both HF and LF are controlled to be OFF or Low are provided in a first period before period A in which HF at a first level is ON, and in a second period after period A. This makes it possible to control radicals and ions and promote exhaust.

[0068] Furthermore, in the plasma processing method according to the third embodiment, in addition to the on / off control of HF and LF in the plasma processing method according to the first embodiment, a fifth level of LF power lower than the LF power in period C is output during period G. This controls the strength of ion attraction during period G, thereby controlling the etching rate and the amount of by-products adhering to the sidewall of a recess formed in the film to be etched.

[0069] The middle level of LF shown in period G is an example of LF power at the fifth level. In this embodiment, LF power at the fifth level is output, and then LF power at a third level lower than the fifth level is output.

[0070] <Fourth embodiment> [Plasma treatment method] Next, a plasma processing method according to a fourth embodiment will be described with reference to Fig. 8. Fig. 8 is a diagram showing an example of the plasma processing method according to the fourth embodiment.

[0071] The plasma processing method according to the fourth embodiment is a combination of the HF control of the plasma processing method according to the second embodiment shown in FIG. 6 and the LF control of the plasma processing method according to the third embodiment shown in FIG. 7. That is, the HF pulse controlled in the plasma processing method according to the fourth embodiment is the same as the HF pulse controlled in the plasma processing method according to the second embodiment. Also, the LF pulse controlled in the plasma processing method according to the fourth embodiment is the same as the LF pulse controlled in the plasma processing method according to the third embodiment. The HF and LF control in the A period to the D3 period of the plasma processing method according to the fourth embodiment and the effects shown in FIG. 8(a) to (d) are the same as the HF and LF control in the A period to the D1 period of the plasma processing method according to the first embodiment and the effects shown in FIG. 4(a) to (e). The HF and LF control in the F period of the plasma processing method according to the fourth embodiment and the effects shown in FIG. 8(f) are the same as the HF and LF control in the F period of the plasma processing method according to the second embodiment and the effects shown in FIG. 6(f).

[0072] In this embodiment, there is a fourth period in which LF power of a fifth level is output in period H, and then HF power of a second level is output before HF power of a first level is output in the following period A. Period D3 is an example of the fourth period.

[0073] In the plasma processing method according to the fourth embodiment, HF power of a first level is output in period A, HF power of a second level is output in periods B, C, and D3, and HF power of a fourth level is output in periods F and H, and this is repeated in sequence. After HF power of the second level is output, LF power of a third level is output in a fourth period (period D3) before HF power of the first level is output in the next period A. LF power of a fifth level is output in period H immediately preceding the fourth period.

[0074] As a result, in the H period, HF is turned on to the middle level, which is the same output level as in the F period, and LF is turned on to the middle level, which is lower than the output levels in the C and F periods and higher than the output level in the D3 period.

[0075] As a result, in the plasma processing method according to the fourth embodiment, both HF and LF are controlled to the middle level during the H period. As an effect of Fig. 8(h), the middle level HF can generate plasma and radicals with a lower density than the plasma density generated by the high level HF during the A period. Also, the middle level LF weakens the strength of attracting ions compared to the C period, and can control the etching rate and the amount of by-products adhering to the sidewall of the recess formed in the etching target film 101 and the mask 102.

[0076] <Fifth embodiment> [Plasma treatment method] Next, a plasma processing method according to a fifth embodiment will be described with reference to Fig. 9. Fig. 9 is a diagram showing an example of the plasma processing method according to the fifth embodiment.

[0077] The plasma processing method according to the fifth embodiment differs from the plasma processing method according to the fourth embodiment in that HF ​​is controlled to be off and LF is controlled to a middle level as shown in the period G instead of the period H of the plasma processing method according to the fourth embodiment. That is, the control and effect of HF and LF in the periods A to D3 and F of the plasma processing method according to the fifth embodiment are the same as those of the plasma processing method according to the fourth embodiment. In other words, the control of HF and LF in the periods A to D3 of the plasma processing method according to the fifth embodiment and the effect shown in Figs. 9(a) to (d) are the same as the control of HF and LF in the periods A to D1 of the plasma processing method according to the first embodiment and the effect shown in Figs. 4(a) to (e). The control of HF and LF in the period F of the plasma processing method according to the fifth embodiment and the effect shown in Fig. 9(f) are the same as the control of HF and LF in the period F of the plasma processing method according to the second embodiment and the effect shown in Fig. 6(f).

[0078] In the plasma processing method according to the fifth embodiment, the HF is off while the LF is controlled to the middle level in the G period. The LF controlled to the middle level in the G period is an example of the fifth level of LF power. The control of the HF and LF in the G period and the effect shown in FIG. 9(g) are the same as the control of the HF and LF in the G period and the effect of the plasma processing method according to the third embodiment.

[0079] In the plasma processing method according to the fifth embodiment, HF power of a first level is output in period A, HF power of a second level is output in periods B, C, G, and D3, and HF power of a fourth level is output in period F, and this is repeated in sequence. After HF power of the second level is output, LF power of a third level is output in a fourth period (period D3) before HF power of the first level is output in the next period A. LF power of a fifth level is output in period G immediately preceding the fourth period.

[0080] According to the plasma processing method of the fifth embodiment, HF power of the fourth level is output during period F, and then LF power of the fifth level is output. At this time, in the plasma processing method of the fourth embodiment, LF power of the fifth level, i.e., middle level, is output while HF power of the fourth level, i.e., middle level, is output. On the other hand, in the plasma processing method of the fifth embodiment, LF power of the fifth level is output after the output of HF power of the fourth level is stopped (i.e., when it is stopped).

[0081] Sixth embodiment [Plasma treatment method] Next, a plasma processing method according to the sixth embodiment will be described with reference to FIG. 10. FIG. 10 is a diagram showing an example of the plasma processing method according to the sixth embodiment. In the plasma processing method according to the sixth embodiment, HF is controlled to three levels, high level (800 W), middle level (500 W) and low level (250 W). It may be controlled to four levels, high level, middle level, low level and off (0 W). LF is controlled to two levels, on and off.

[0082] 6, the plasma processing method according to the second embodiment is controlled so that a fourth level, i.e., a middle level, HF power is output in periods F and E. In contrast, the plasma processing method according to the sixth embodiment is controlled so that a middle level HF power is output in period F, and then a sixth level, i.e., a low level, HF power is output in period E.

[0083] That is, in this embodiment, the HF power is controlled to be output at the sixth level after the HF power at the fourth level is output and before the HF power at the first level is output. Note that the HF may be controlled to be off in the B period, the C period, and the D2 period, or may be controlled to a power level lower than the sixth level. Note that the LF power is output at the third level except for the I period (the C period and the first half of the F period).

[0084] In the plasma processing method according to the sixth embodiment, HF power of a first level is output in period A, HF power of a second level is output in periods B, C, and D2, HF power of a fourth level is output in period F, and HF power of a sixth level is output in period E. After HF power of the second level is output, LF power of a third level is output in a third period (period D2) before HF power of the first level is output in the next period A.

[0085] [Duty ratio] The possible values ​​of the duty ratio and the like in the plasma processing method according to the sixth embodiment will be described with reference to Fig. 10. The present invention is also applicable to the plasma processing methods according to the first to fifth embodiments. As shown in Fig. 10 as an example, the cycle period is indicated by xFeq (frequency), for example, and xFeq is in the range of 0.1 to 2 kHz.

[0086] LF Duty, which indicates the ratio (proportion) that LF is on during one cycle, is set in the range of 1 to 90%. Offset is 0 to 99%. The sum of LF Duty and offset is set to a value smaller than 100%.

[0087] HF Duty1 to Duty5 shown in Fig. 10 have a resolution of, for example, 1%. The HF power in period A is controlled to, for example, 800 W. The HF power in period A may be in the range of 50 to 2000 W. The HF power in period A may be in the range of 100 to 1000 W.

[0088] The HF power in periods B and C is controlled to, for example, 0 W, that is, off. The HF power in periods B and C may be in the range of 50 to 2000 W. The HF power in periods B and C may be in the range of 100 to 1000 W.

[0089] The HF power in the F period is controlled to, for example, 500 W. The HF power in the F period may be in the range of 50 to 2000 W. The HF power in the F period may be in the range of 100 to 1000 W.

[0090] The HF power in the E period is controlled to, for example, 250 W. The HF power in the E period may be in the range of 50 to 2000 W. The HF power in the E period is controlled to, for example, 0 W, that is, off. The HF power in the E period may be in the range of 100 to 1000 W.

[0091] The HF power in the D2 period is controlled to, for example, 0 W, that is, off. The HF power in the D2 period may be in the range of 50 to 2000 W. The HF power in the D2 period may be in the range of 100 to 1000 W.

[0092] HF Duty1 in period A, HF Duty2 in period B+C, HF Duty3 in period F, HF Duty4 in period E, and HF Duty5 in period D2 can each be set in the range of 1 to 90%. HF Duty1 to Duty5 are determined so that the total value of the five duty ratios of HF Duty1 to Duty5 is 100%. The total value of the five duty ratios of HF Duty1 to Duty5 is set to a value smaller than 100%.

[0093] As described above, the plasma processing methods according to the first to sixth embodiments can be used according to the type and characteristics of the process. For example, by providing a middle level of LF, the degree of ion attraction can be controlled by changing the power level of the LF. By using the plasma processing methods according to the first to sixth embodiments according to the type and characteristics of the process, the performance of the process can be improved.

[0094] The appropriate values ​​of HF and LF, such as high level, middle level, and low level, vary depending on the type of film 101 to be etched. Therefore, the optimal HF and LF levels according to the film 101 to be etched are calculated in advance from the above-mentioned allowable power range and stored in the storage unit. The control unit 2 refers to the storage unit and controls the HF and LF levels to optimal values ​​according to the process parameters and the type of film 101 to be etched. This can further improve the process performance.

[0095] Furthermore, by adjusting various parameters, it is possible to achieve a high selectivity ratio of the mask to the film 101 to be etched. For example, the various parameters include the time of each step (on, off, etc.) of each cycle, the gas ratio of the processing gas used in the plasma processing, the set output (high power, low power) of HF and LF, the pulse period of HF and LF, and the duty ratio of HF and LF.

[0096] By using the plasma processing methods according to the first to sixth embodiments appropriately and adjusting the parameters, the process performance can be improved. As an example of the process performance improvement, it is possible to improve the etching rate, suppress bowing, protect the mask, suppress clogging of the mask, and promote exhaust of by-products from recesses formed in the film 101 to be etched. As another example of the process performance improvement, it is possible to obtain high perpendicularity of holes for each process, enabling highly anisotropic etching. As another example of the process performance improvement, it is possible to suppress variation in the CD (Critical Dimension) value of recesses formed in the film 101 to be etched.

[0097] The plasma processing apparatus and the plasma processing method according to the embodiments disclosed herein should be considered as illustrative and not restrictive in all respects. The embodiments can be modified and improved in various ways without departing from the scope and spirit of the appended claims. The matters described in the above embodiments can be configured in other ways as long as they are not inconsistent, and can be combined as long as they are not inconsistent.

[0098] The plasma processing apparatus of the present disclosure can be applied to any type of apparatus, including atomic layer deposition (ALD) apparatus, capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron cyclotron resonance plasma (ECR), and helicon wave plasma (HWP). [Explanation of symbols]

[0099] 1. Plasma processing equipment 2. Control section 2a Computer 2a1 Processing section 2a2 Storage section 2a3 Communication Interface 10 Plasma Processing Chamber 11 Substrate support 13. Shower Head 21 Gas Source 20 Gas supply section 30 power supply 31 RF power supply 31a First RF generation unit 31b Second RF generation unit 32a First DC generation unit 32b Second DC generation section 40 Exhaust system 100 Silicon substrate 101 Film to be etched 102 Mask 111 Main body 112 Ring Assembly

Claims

1. a processing vessel capable of being evacuated; a first electrode disposed in the processing chamber and supporting a substrate to be processed; a second electrode or antenna provided opposite the first electrode; a first high frequency power supply unit connected to the first electrode, the second electrode, or the antenna and configured to supply a first high frequency power for generating plasma to the first electrode, the second electrode, or the antenna; a second high frequency power supply unit connected to the first electrode and configured to supply a second high frequency power for bias 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 is outputting the first high frequency power at a first level and the first high frequency power at a second level lower than the first level from the first high frequency power supply unit in sequence; after the first high frequency power supply unit outputs the first high frequency power at the second level, the second high frequency power supply unit outputs the second high frequency power at a third level during a first period before the first high frequency power at the first level is output, a second period is provided between the output of the first high frequency power at the second level and the output of the second high frequency power at the third level; outputting the second high frequency power at the third level during the first period, and then outputting the first high frequency power at a fourth level that is lower than the first level and higher than the second level; a third period in which the first high frequency power of the second level and the second high frequency power of a low level lower than the third level are outputted after the first high frequency power of the fourth level is outputted and before the first high frequency power of the first level is outputted, a plasma processing apparatus that performs control so as to process a substrate to be processed with plasma generated from a processing gas supplied into the processing vessel in accordance with outputs of the first high frequency power and the second high frequency power.

2. The control unit is a control is performed so that the second high frequency power of a fifth level, which is lower than the third level and higher than the low level, is outputted after the second high frequency power of the third level is outputted and before the first high frequency power of the first level is outputted. The plasma processing apparatus according to claim 1 .

3. The control unit is control so as to have a fourth period during which the first high frequency power at the second level is output after the second high frequency power at the fifth level is output and before the first high frequency power at the first level is output; The plasma processing apparatus according to claim 2 .

4. The control unit is controlling the output of the first high frequency power at the fourth level and then the output of the second high frequency power at the fifth level; The plasma processing apparatus according to claim 3 .

5. The control unit is controlling the output of the second high frequency power at the fifth level while the first high frequency power at the fourth level is being output; The plasma processing apparatus according to claim 4 .

6. The control unit is control so as to stop output of the first high frequency power at the fourth level and then output the second high frequency power at the fifth level; The plasma processing apparatus according to claim 4 .

7. The control unit is control so that the first high frequency power of a sixth level, which is lower than the fourth level and higher than the second level, is output after the first high frequency power of the fourth level is output and before the first high frequency power of the first level is output; The plasma processing apparatus according to claim 1 .

8. The LF Duty, which indicates the ratio of time that the LF is on during one cycle, is set in the range of 1 to 90%. The plasma processing apparatus according to any one of claims 1 to 7.

9. a processing vessel capable of being evacuated; a first electrode disposed in the processing chamber and supporting a substrate to be processed; a second electrode or antenna provided opposite the first electrode; a first high frequency power supply unit connected to the first electrode, the second electrode, or the antenna and configured to supply a first high frequency power for generating plasma to the first electrode, the second electrode, or the antenna; a second high frequency power supply unit connected to the first electrode and configured to supply a second high frequency power for bias to the first electrode; A plasma processing method performed in a plasma processing apparatus comprising: outputting the first high frequency power at a first level and the first high frequency power at a second level lower than the first level from the first high frequency power supply unit in sequence; after the first high frequency power supply unit outputs the first high frequency power at the second level, the second high frequency power supply unit outputs the second high frequency power at a third level during a first period before the first high frequency power at the first level is output, a second period is provided between the output of the first high frequency power at the second level and the output of the second high frequency power at the third level; outputting the second high frequency power at the third level during the first period, and then outputting the first high frequency power at a fourth level that is lower than the first level and higher than the second level; a third period in which the first high frequency power of the second level and the second high frequency power of a low level lower than the third level are outputted after the first high frequency power of the fourth level is outputted and before the first high frequency power of the first level is outputted, a substrate to be processed is processed with plasma generated from a processing gas supplied into the processing chamber in response to outputs of the first high frequency power and the second high frequency power. Plasma treatment method.

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