Substrate processing method and substrate processing apparatus

Abstract

A substrate processing method is a substrate processing method in a substrate processing apparatus, including the following steps: step a), supplying a process gas of a specific condition to a processing container in which a stage for placing a processed object having an etching film and a mask on the etching film is placed; step b), performing plasma processing on the processed object by a first plasma of the process gas generated under first plasma generation conditions; step c), performing plasma processing on the processed object by a second plasma of the process gas generated under second plasma generation conditions, the second plasma generation conditions being plasma generation conditions in which conditions other than a condition of high-frequency power and a processing time in the first plasma generation conditions are the same; and step d), repeating the step b) and the step c).

Description

Technical Field

[0001] This disclosure relates to a substrate processing method and a substrate processing apparatus. Background Technology

[0002] In recent years, with the advancement of semiconductor miniaturization, damage to the sidewalls of holes in dry etching processes, such as changes in the composition of the object or penetration, has become a problem. In contrast, for example, it has been proposed to mitigate sidewall damage by repeating the steps of depositing a protective film and etching.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2013-021192

[0006] Patent Document 2: Japanese Patent Application Publication No. 2007-129260 Summary of the Invention

[0007] The problem the invention aims to solve

[0008] This disclosure provides a substrate processing method and a substrate processing apparatus capable of high-speed and low-damage etching compared to gas switching methods.

[0009] Solution for solving the problem

[0010] One aspect of the substrate processing method disclosed herein is a substrate processing method in a substrate processing apparatus, the substrate processing method comprising the following steps: step a), supplying a process gas under specific conditions to a processing container provided with a stage for placing a workpiece having an etched film and a mask on the etched film; step b), plasma processing the workpiece using a first plasma of a process gas generated under a first plasma generation condition; step c), plasma processing the workpiece using a second plasma of a process gas generated under a second plasma generation condition, the second plasma generation condition being a plasma generation condition that differs from the high-frequency power condition and processing time in the first plasma generation condition but is otherwise identical; and step d), repeating steps b) and c).

[0011] The effects of the invention

[0012] According to this disclosure, etching with high speed and low damage compared to gas switching methods can be performed. Attached Figure Description

[0013] Figure 1 This is a diagram illustrating an example of a plasma processing apparatus according to a first embodiment of the present disclosure.

[0014] Figure 2 This is a diagram illustrating an example of etching performed by a highly dissociative plasma.

[0015] Figure 3 This is a diagram illustrating an example of deposition via low-dissociation plasma.

[0016] Figure 4 This is a diagram illustrating an example of a reaction carried out by high-dissociation plasma and low-dissociation plasma in the first embodiment.

[0017] Figure 5 This is a flowchart illustrating an example of the etching process in the first embodiment.

[0018] Figure 6 This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas.

[0019] Figure 7 This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas.

[0020] Figure 8 This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas.

[0021] Figure 9 This is a diagram schematically illustrating an example of the state of a wafer during plasma processing.

[0022] Figure 10 This is a diagram illustrating an example of the experimental results in the first embodiment.

[0023] Figure 11 This is a diagram illustrating one example of the experimental results in the comparative examples.

[0024] Figure 12 This is a diagram illustrating an example of a reaction carried out using high-dissociation plasma, medium-dissociation plasma, and low-dissociation plasma in the second embodiment.

[0025] Figure 13 This is a flowchart illustrating an example of the etching process in the second embodiment.

[0026] Figure 14 This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas.

[0027] Figure 15 This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas.

[0028] Figure 16This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas.

[0029] Figure 17 This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas. Detailed Implementation

[0030] Hereinafter, embodiments of the substrate processing method and substrate processing apparatus of this disclosure will be described in detail with reference to the accompanying drawings. Furthermore, the technology of this disclosure is not intended to be limited by the following embodiments.

[0031] In etching processes, the process gas used must be switched while repeatedly performing the steps of depositing a protective film and etching. Therefore, replacing the process gas within the processing vessel takes time. This increases processing time and reduces productivity. Thus, a high-speed, low-damage etching method is desired compared to gas switching methods.

[0032] (First Implementation)

[0033] [Structure of the plasma processing device 100]

[0034] Figure 1 This is a diagram illustrating an example of a plasma processing apparatus according to a first embodiment of the present disclosure. The plasma processing apparatus 100 includes a main body 10 and a control unit 20. In this embodiment, the plasma processing apparatus 100 uses inductively coupled plasma (ICP) to etch a film formed on a semiconductor wafer (hereinafter also referred to as a wafer) W, which is an example of a workpiece. In this embodiment, the semiconductor wafer W has, for example, an etchable film and a mask formed on the etchable film.

[0035] The main body 10 has a generally cylindrical, hermetically sealed chamber 101 made of aluminum, for example, with its inner wall surface anodized. The chamber 101 is grounded. The chamber 101 is divided vertically by an upper top plate 102. The upper surface of the upper top plate 102 serves as an antenna chamber 103 for housing an antenna 113. The lower surface of the upper top plate 102 serves as a processing chamber 104 for generating plasma. In this embodiment, the upper top plate 102 is formed of quartz and constitutes the top wall of the processing chamber 104. Alternatively, the upper top plate 102 may also be made of ceramic such as Al2O3.

[0036] A gas supply pipe 124 is provided on the side wall 104a of the processing chamber 104. One end of the gas supply pipe 124 is connected to the space S inside the processing chamber 104, and the other end is connected to the gas supply mechanism 120. Gas supplied from the gas supply mechanism 120 is supplied to the space S via the gas supply pipe 124. The gas supply mechanism 120 includes gas supply sources 121a-121c, MFC (Mass Flow Controller) 122a-122c, and valves 123a-123c. The gas supply mechanism 120 is an example of a gas supply unit.

[0037] MFC 122a is connected to a gas supply source 121a that supplies carbon-containing gas, and controls the flow rate of the carbon-containing gas supplied from the gas supply source 121a. In this embodiment, the gas supply source 121a supplies, for example, C4F8 gas or C4F6 gas. Valve 123a controls the supply and cessation of the carbon-containing gas, whose flow rate is controlled by MFC 122a, to the gas supply pipe 124.

[0038] MFC 122b is connected to a gas supply source 121b that supplies halogen-containing gas and controls the flow rate of the halogen-containing gas supplied from the gas supply source 121b. In this embodiment, the gas supply source 121b supplies, for example, SF6 gas. Valve 123b controls the supply and cessation of the halogen-containing gas, whose flow rate is controlled by MFC 122b, to the gas supply pipe 124.

[0039] MFC 122c is connected to a gas supply source 121c that supplies rare gas and controls the flow rate of rare gas supplied from the gas supply source 121c. In this embodiment, the gas supply source 121c supplies, for example, Ar gas. Valve 123c controls the supply and cessation of the rare gas supply to the gas supply pipe 124, the flow rate of which is controlled by MFC 122c.

[0040] An antenna 113 is installed inside the antenna chamber 103. The antenna 113 has antenna leads 113a made of highly conductive metals such as copper and aluminum. The antenna leads 113a are formed in any shape, such as a loop or a spiral. The antenna 113 is separated from the upper top plate 102 by an insulating member 117.

[0041] One end of a power supply component 116 extending upwards towards the antenna chamber 103 is connected to terminal 118 of antenna lead 113a. One end of a power supply line 119 is connected to the other end of the power supply component 116, and a high-frequency power supply 115 is connected to the other end of the power supply line 119 via a matching adapter 114. The high-frequency power supply 115 supplies high-frequency power at frequencies above 10 MHz (e.g., 27 MHz) to the antenna 113 via the matching adapter 114, power supply line 119, power supply component 116, and terminal 118. This creates an induced electric field in the space S within the processing chamber 104 below the antenna 113, which plasmaizes the gas supplied from the gas supply pipe 124, generating inductively coupled plasma in space S. The antenna 113 is an example of a plasma generation unit. Furthermore, in the following description, the high-frequency power supplied from the high-frequency power supply 115 may sometimes be referred to as a second high-frequency power, a source, or a source.

[0042] A circular base 126, made of a conductive material such as aluminum, is provided on the bottom wall of the processing chamber 104. This base 126 is used to hold the wafer to be processed. The base 126 also functions as an electrode to attract ions (for biasing) in the generated plasma. The base 126 is supported by a cylindrical base support 127 made of an insulator.

[0043] Additionally, the base 126 is connected to a high-frequency power supply 128 for biasing via a power supply rod 130 and a matching device 129. High-frequency power at a frequency of 10 MHz or higher (e.g., 13 MHz) is supplied to the base 126 from the high-frequency power supply 128. Furthermore, in the following description, the high-frequency power supplied from the high-frequency power supply 128 may sometimes be referred to as first high-frequency power, bias, or bias. Additionally, the high-frequency power supply 128 sometimes functions as a plasma excitation power supply to generate plasma within space S. This plasma is capacitively coupled plasma (CCP).

[0044] An electrostatic holding disk 131 for holding the wafer W by electrostatic attraction is provided on the upper surface of the base 126. An edge ring 132 is provided on the outer periphery of the electrostatic holding disk 131 in a manner that surrounds the wafer W. The edge ring 132 is sometimes also referred to as a focusing ring.

[0045] Additionally, a flow path 133 for circulating refrigerant, such as cooling water, is formed inside the base 126. The flow path 133 is connected to a cooling unit (not shown) via a pipe 134, from which temperature-regulated refrigerant is supplied into the flow path 133 via the pipe 134.

[0046] A gas supply pipe 135 is provided inside the base 126 for supplying a heat transfer gas, such as He gas, between the electrostatic holding pad 131 and the wafer W. The gas supply pipe 135 passes through the electrostatic holding pad 131, connecting the space inside the gas supply pipe 135 with the space between the electrostatic holding pad 131 and the wafer W. Furthermore, multiple lifting pins (not shown) for transferring the wafer W are provided in the base 126 in a manner that allows them to protrude from and retract into the upper surface of the electrostatic holding pad 131.

[0047] A loading / unloading outlet 140 is provided on the side wall 104a of the processing chamber 104 for loading and unloading wafers W into and out of the processing chamber 104. The loading / unloading outlet 140 can be opened and closed by a gate valve G. By controlling the gate valve G to the open state, wafers W can be loaded and unloaded through the loading / unloading outlet 140. In addition, an annular partition 141 with a large number of through holes is provided between the outer side wall of the base support portion 127 and the side wall 104a of the processing chamber 104.

[0048] An exhaust port 142 is formed on the bottom wall of the processing chamber 104, and an exhaust mechanism 143 is provided at the exhaust port 142. The exhaust mechanism 143 includes an exhaust pipe 144 connected to the exhaust port 142, an APC (Auto Pressure Controller) valve 145 for controlling the pressure inside the processing chamber 104 by adjusting the opening of the exhaust pipe 144, and a vacuum pump 146 for venting the processing chamber 104 through the exhaust pipe 144. By venting the processing chamber 104 through the vacuum pump 146, the processing chamber 104 is maintained at a specified vacuum level during the plasma etching process by adjusting the opening of the APC valve 145.

[0049] The control unit 20 includes memory such as ROM (Read Only Memory) and RAM (Random Access Memory) and a processor such as a CPU (Central Processing Unit). The processor in the control unit 20 controls the various parts of the main body 10 by reading and executing programs stored in the memory within the control unit 20. The specific processing performed by the control unit 20 will be described later.

[0050] [Switching between etching and deposition based on plasma dissociation]

[0051] Here, use Figure 2 and Figure 3 This illustrates the switching between etching and deposition based on the degree of plasma dissociation. Figure 2 This is a diagram illustrating an example of etching performed by a highly dissociative plasma. Figure 3This is a diagram illustrating an example of deposition via low-dissociation plasma. In Figure 2 In this process, a silicon film is used as the etched film on wafer W, and a silicon oxide film is used as a mask. Additionally, in... Figure 3 In the process, deposits are formed on the silicon film on wafer W.

[0052] exist Figure 2 and Figure 3 Regarding the process gas, as a common specific condition, a mixture of SF6, C4F8, C4F6, and Ar at specified flow rates is used. Furthermore, the pressure in processing chamber 104 is set to 20 mTorr, and the processing time is set to 300 seconds.

[0053] Figure 2 This is an example of plasma processing where the high-frequency power (source) supplied from high-frequency power source 115 is set to 900W (CW, continuous wave) and the high-frequency power (bias) supplied from high-frequency power source 128 is set to 150W (CW). In this case, as... Figure 2 As shown, the silicon film 201 was etched by the high dissociation plasma and the mask 202 respectively.

[0054] Figure 3 This is an example of plasma processing where the high-frequency power (source) supplied from high-frequency power source 115 is set to 900W (1kHz, 5% duty cycle) and the high-frequency power (bias) supplied from high-frequency power source 128 is set to 0W. In this case, as... Figure 3 As shown, it can be seen that deposit 204 is deposited on silicon film 203 by low-dissociation plasma. That is, it can be seen that by controlling the applied high-frequency power to switch between low-dissociation plasma and high-dissociation plasma, etching and protective film deposition can be repeated.

[0055] Next, use Figure 4 To illustrate the reactions in each plasma. Figure 4 This is a diagram illustrating an example of the reaction carried out via high-dissociation plasma and low-dissociation plasma in the first embodiment. Figure 4 In the diagram, the reaction state in the low-dissociation plasma P1 is schematically shown in the left half, and the reaction state in the high-dissociation plasma P2 is schematically shown in the right half. (See diagram for reference.) Figure 4As shown, fluorinated carbon gases such as C4F8 and C4F6, used as the main gas, are introduced into the processing chamber 104, and halogen-containing gases such as SF6 and NF3, used as additive gases, are also introduced into the processing chamber 104. Furthermore, it is preferable that the halogen-containing gases are carbon-free. Additionally, the halogen-containing gases are supplied to replenish the etchant, and therefore may not always be supplied. Furthermore, an etchable film 210 as a silicon film and a mask 211 as a silicon oxide film are formed on the wafer W. The wafer W, the etchable film 210, and the mask 211 are shown schematically with an enlarged view.

[0056] Within the low-dissociation plasma P1, C4F8 dissociates, for example, into C4F7 and F, and SF6 dissociates, for example, into SF5 and F. In this case, C4F7 is generated as a large amount of deposit, while the amount of etchant (F) generated from SF6 is small. Due to its high adhesion coefficient, C4F7 forms deposits (reaction products) 212 on the mask 211 and on the sidewalls of the holes (cavities) of the etched film 210. In other words, a precursor for forming deposits on the wafer W is generated within the low-dissociation plasma P1. Furthermore, in the following description, the low-dissociation plasma P1 is sometimes referred to as the first plasma.

[0057] On the other hand, within the high dissociation plasma P2, C4F8 dissociates, for example, into C2F4 → CF2, or further into CF2 → CF and F. Additionally, SF6 dissociates, for example, into SFx and multiple F. In this case, a large amount of etchant (CF2, F) is generated. Furthermore, CF2, due to its low adhesion coefficient, reaches the bottom of the hole (cavity), and etching progresses. In other words, a precursor for etching the film is generated within the high dissociation plasma P2. Furthermore, in the following description, the high dissociation plasma P2 is sometimes referred to as the second plasma.

[0058] [Etching Method]

[0059] Next, the etching method involved in the first embodiment will be described. Figure 5 This is a flowchart illustrating an example of the etching process in the first embodiment.

[0060] In the etching method according to the first embodiment, the control unit 20 opens the gate valve G of the loading / unloading outlet 140, and loads the wafer W, on which the mask 211 is formed on the etched film 210, into the processing chamber 104 and places it on the electrostatic holding disk 131 of the base 126. The wafer W is held on the electrostatic holding disk 131 by applying a DC voltage. Afterwards, the control unit 20 closes the gate valve G and controls the exhaust mechanism 143, thereby venting gas from the space S to make the atmosphere of the space S a predetermined vacuum. In addition, the control unit 20 adjusts the temperature by controlling a temperature control module (not shown) to make the temperature of the wafer W a predetermined temperature (step S1).

[0061] Next, the control unit 20 initiates the supply of process gas (step S2). The control unit 20 supplies a mixture of C4F8, C4F6, SF6, and Ar to the processing chamber 104 via the gas supply pipe 124 as the process gas, which includes fluorinated carbon gas, halogenated gas, and rare gases. The supplied mixture fills the space S within the processing chamber 104. Furthermore, the fluorinated carbon gas can be other compounds with carbon-fluorine bonds, such as CF2 or C3F4. Additionally, hydrofluorocarbon gases such as CHF3 and CH2F2 can also be used, for example. Furthermore, in the first embodiment, the process gas conditions are set to be the same as before the etching process is completed.

[0062] The control unit 20 supplies a first high-frequency power (bias) for plasma excitation and biasing to the base 126 by controlling the high-frequency power supply 128. In space S, a mixed-gas plasma is generated by supplying the first high-frequency power for plasma excitation and biasing to the base 126. That is, in space S, a precursor for forming a deposit is generated using the first plasma (low-dissociation plasma P1) generated by the first high-frequency power. The generated plasma is used to perform plasma treatment on the wafer W. Specifically, the control unit 20 performs plasma treatment on the wafer W using the first plasma of the process gas generated under the first plasma generation conditions (step S3). The wafer W is exposed to the first plasma to form a deposit (reaction product) 212 on the mask 211, on the sidewalls of the holes (cavities) of the etched film 210. Furthermore, the first plasma is a capacitively coupled plasma (CCP) generated by the first high-frequency power applied to the base 126.

[0063] The control unit 20 supplies a second high-frequency power (source) for plasma excitation to the antenna 113 by controlling the high-frequency power supply 115. A mixed-gas plasma is generated by the induced electric field formed in space S. That is, in space S, a precursor for etching the etched film 210 is generated using the second plasma (high dissociation plasma P2) generated by the second high-frequency power. Additionally, the control unit 20 supplies a first high-frequency power (bias voltage) for bias voltage, which has a lower output than in step S3, to the base 126 by controlling the high-frequency power supply 128. The generated plasma is used to perform plasma processing on the wafer W. Specifically, the control unit 20 performs plasma processing on the wafer W (step S4) using a second plasma of process gas generated under second plasma generation conditions, which differ from the high-frequency power conditions and processing time in the first plasma generation conditions but are otherwise identical. The wafer W is exposed to the second plasma, and ions and free radicals are attracted to the wafer W side by a bias potential, so that the etching of the etched film 210 that is not covered by the mask 211 can proceed. In addition, the etching time of step S4 by the second plasma is set to a time that will not remove the deposits formed on the sidewalls of the hole in step S3, that is, a time that will not cause damage to the sidewalls.

[0064] The control unit 20 determines whether a predetermined shape has been obtained through steps S3 and S4 (step S5). If the control unit 20 determines that the predetermined shape has not been obtained (step S5: "No"), the process returns to step S3. On the other hand, if the control unit 20 determines that the predetermined shape has been obtained (step S5: "Yes"), the process ends. Furthermore, the control unit 20 may also include the following step between steps S3 and S4, or between steps S4 and S5: stopping the supply of the first high-frequency power and the second high-frequency power to stop plasma generation for a predetermined time.

[0065] When the process is finished, the control unit 20 stops supplying the process gas. Additionally, the control unit 20 applies opposite DC voltages to the electrostatic holding tray 131 to remove static electricity, thereby stripping the wafer W from the electrostatic holding tray 131. The control unit 20 then opens the gate valve G. The wafer W is then removed from the space S of the processing chamber 104 via the inlet / outlet 140. In this way, high-speed and low-damage etching can be performed in the plasma processing apparatus 100 compared to gas switching methods. Furthermore, it is possible to maintain a vertical shape during etching while achieving both high mask selectivity and high etch rate.

[0066] [High-frequency power application mode]

[0067] Next, use Figures 6 to 8 This is used to illustrate the relationship between the application mode of high-frequency electricity and the degree of dissociation of process gas. Figures 6 to 8 This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas.

[0068] Figure 6 The application mode 220 shown is an example of a mode in which one or more of the first high-frequency power (Bias) and the second high-frequency power (Source) are continuously supplied in cycle 221, which is a unit cycle. In application mode 220, the first high-frequency power switches between "High" and "Low", and the second high-frequency power switches between "Off" and "On". The first high-frequency power can be set, for example, to 150W (CW) for "High" and 75W (CW) for "Low". The second high-frequency power can be set, for example, to 0W for "Off" and 1100W for "On", which is 1100W (10Hz, 50% duty cycle).

[0069] In application mode 220, curve 222, representing the degree of dissociation of the process gas, is in the high-dissociation etching region 223 when the second high-frequency power is "on" and the first high-frequency power is "low". When the second high-frequency power switches to "off" and the first high-frequency power switches to "high", the degree of dissociation decreases, slowly transitioning to the low-dissociation deposition region 224. In application mode 220, the deposition and etching steps are repeated by repeating cycle 221.

[0070] Figure 7 The application mode 230 shown is an example of a mode in which the second high-frequency power (Source) is also "disconnected" simultaneously with the "disconnection" of the first high-frequency power (Bias) in cycle 231, which is a unit cycle. That is, application mode 230 includes a process of applying high-frequency power without generating new plasma. In application mode 230, the first high-frequency power switches between "high," "low," and "disconnected," while the second high-frequency power switches between "disconnected" and "on." The first high-frequency power can be set, for example, to 150W (CW) for "high," 75W (CW) for "low," and 0W for "disconnected." The second high-frequency power can be set, for example, to 0W for "disconnected" and 1100W for "on," which is 1100W (10Hz, 50% duty cycle).

[0071] In application mode 230, curve 232, representing the degree of dissociation of the process gas, is in the high-dissociation etching region 223 when the second high-frequency power is "on" and the first high-frequency power is "low". When both the first and second high-frequency powers are "off", curve 232 rapidly shifts to the low-dissociation deposition region 224. Subsequently, when the second high-frequency power is "off" and the first high-frequency power is "high", curve 232 maintains a fixed degree of dissociation in the low-dissociation deposition region 224. In application mode 230, the deposition and etching steps are repeated by repeating cycle 231.

[0072] Figure 8 The application mode 240 shown is an example of a mode in cycle 241, which is a unit cycle, where after the first high-frequency power (Bias) is "high," there is a period where both the first high-frequency power and the second high-frequency power (Source) are "off." That is, application mode 240 includes a process of applying high-frequency power without generating new plasma. In application mode 240, the first high-frequency power switches between "high," "off," and "low," and the second high-frequency power switches between "off" and "on." The first high-frequency power can be set, for example, to 150W (CW) for "high," 0W for "off," and 75W (CW) for "low." Furthermore, the second high-frequency power can be set, for example, to 0W for "off" and 1100W for "on," which is 1100W (10Hz, 50% duty cycle).

[0073] In application mode 240, curve 242, representing the degree of dissociation of the process gas, is in the high-dissociation etching region 223 when the second high-frequency power is "on" and the first high-frequency power is "low". When the second high-frequency power switches to "off" and the first high-frequency power switches to "high", the degree of dissociation decreases. When both the first and second high-frequency powers are "off", curve 242 rapidly shifts to the low-dissociation deposition region 224, and then becomes an undissociated state. In application mode 240, the deposition and etching steps are repeated by repeating cycle 241.

[0074] Furthermore, in the high-frequency power application mode, when the degree of dissociation of the process gas shifts from a high dissociation state (etching) to a low dissociation state (deposition), the presence of residual components from the high dissociation state in the low dissociation state can sometimes affect the deposition characteristics. Therefore, it is more preferable, as in application mode 230, to pause the application of the first high-frequency power during the switch from a high dissociation state until the residual components from the high dissociation state disappear. Moreover, during the transition from a low dissociation state to a high dissociation state, even if residual components from the low dissociation state are present, they will dissociate directly, thus minimizing the impact on etching characteristics.

[0075] [Wafer state during plasma processing]

[0076] Next, use Figure 9 This is to illustrate the state of the wafer during plasma processing. Figure 9 This is a diagram schematically illustrating an example of the state of a wafer during plasma processing. Figure 9 The diagram schematically shows a cross-section of wafer W during plasma processing, depicting the etching of the aperture (hole) of the etched film 210 through the opening of mask 211. A protective film 251 composed of deposits is formed on the surface of mask 211 and the sidewalls of the aperture. However, no protective film 251 is formed on the bottom 252 of the aperture. At the bottom 252 of the aperture, by repeatedly performing the deposition and etching steps, the formation of the protective film 251 on the sidewalls of the aperture, the etching of the bottom 252 of the aperture, and the formation of the protective film 251 on the sidewalls of the etched film 210 exposed by etching are meticulously repeated. This reduces damage to the sidewalls of the aperture.

[0077] [Experimental Results]

[0078] Next, use Figure 10 and Figure 11 To illustrate the experimental results. Figure 10 This is a diagram illustrating an example of the experimental results in the first embodiment. (See diagram for example.) Figure 10 As shown, in the experiment of the first embodiment, with Figure 6 The application mode 220 shown applies a high-frequency power to a wafer W having a silicon oxide film 261 serving as a mask on a silicon film 260. The first high-frequency power (Bias) is set to "Low" at 75W (CW) and "High" at 150W (CW). Additionally, the second high-frequency power (Source) is set to 1100W (10Hz, 50% duty cycle). That is, Figure 10 The application mode is a cycle of 100 ms, switching between deposition and etching every 50 ms. That is, the process switches from etching to deposition when the protective film on the sidewalls disappears. A mixture of C4F8, C4F6, SF6, and Ar was used as the process gas. The processing time was set to 900 seconds, and the pressure inside the processing chamber 104 was set to 20 mTorr. As a result, the sidewalls of the etched holes in the silicon film 260 do not suffer from wall depressions (scallops) and instead have smooth sidewalls.

[0079] Figure 11 This is a diagram illustrating one example of the experimental results in the comparative examples. For example... Figure 11As shown, in the comparative example experiment, a high-frequency power was applied to a wafer having a silicon oxide film 263 serving as a mask on a silicon film 262, using an application mode that switched between deposition and etching every 30 seconds for both the source and bias. Regarding the source, it was set to 1100W (1kHz, 5% duty cycle) during deposition and 1100W (CW) during etching. Regarding the bias, it was set to 125W (CW) during deposition and 75W (CW) during etching. That is, Figure 11 The application mode was a 60-second cycle, switching between deposition and etching every 30 seconds. A mixture of C4F8, C4F6, SF6, and Ar was used as the process gas. The processing time was set to 10 cycles (600 seconds), and the pressure within the processing chamber 104 was set to 20 mTorr. As a result, the sidewalls of the etched apertures in the silicon film 262 produced fan-shaped grooves 264 corresponding to the switching between deposition and etching. Figure 10 and Figure 11 The experimental results show that, in the first embodiment, low-damage etching is possible.

[0080] (Second Implementation)

[0081] In the first embodiment described above, a deposit 212 is formed on the sidewall of the hole portion of the etched film 210 on the mask 211 using a first plasma. However, the deposit can also be attached to the middle portion of the hole using a third plasma with a process gas having a higher degree of dissociation than the first plasma and a lower degree of dissociation than the second plasma. This embodiment will be described as the second embodiment. Furthermore, descriptions of repetitive structures and operations are omitted by using the same reference numerals for structures identical to those in the plasma processing apparatus 100 of the first embodiment. In the following description, the first plasma will be described as a low-dissociation plasma, the second plasma as a high-dissociation plasma, and the third plasma as a medium-dissociation plasma.

[0082] First, use Figure 12 The reactions in each plasma of the second embodiment will be explained. Figure 12 This is a diagram illustrating an example of a reaction carried out by high-dissociation plasma, medium-dissociation plasma, and low-dissociation plasma in the second embodiment. Figure 12 In the diagram, the reaction state in the low-dissociation plasma P11 is schematically shown on the left, the reaction state in the medium-dissociation plasma P12 is schematically shown in the center, and the reaction state in the high-dissociation plasma P13 is schematically shown on the right. (See diagram for reference.) Figure 12As shown, fluorinated carbon gases such as C4F8 and C4F6, used as the main gas, are introduced into the processing chamber 104, and halogen-containing gases such as SF6 and NF3, used as additive gases, are also introduced into the processing chamber 104. Furthermore, it is preferable that the halogen-containing gases are carbon-free. Additionally, the halogen-containing gases are supplied to replenish the etchant, and therefore may not always be supplied. Furthermore, an etchable film 210 as a silicon film and a mask 211 as a silicon oxide film are formed on the wafer W. The wafer W, the etchable film 210, and the mask 211 are shown schematically with an enlarged view.

[0083] Within the low dissociation plasma P11, and Figure 4 Similarly, within the low-dissociation plasma P1 shown, C4F8 dissociates, for example, into C4F7 and F, and SF6 dissociates, for example, into SF5 and F. Furthermore, in... Figure 12 The illustration of SF6 is omitted. In this case, C4F7 is generated as a large amount of deposit, while the etchant (F) generated from SF6 is small. Due to its high adhesion coefficient, C4F7 forms deposits (reaction products) 212 on the mask 211, on the upper part of the sidewalls of the holes (holes) of the etched film 210. That is, a precursor for forming deposits on the wafer W is generated within the low-dissociation plasma P11. On the other hand, as etching progresses and the holes of the etched film 210 become deeper, in the case of low-dissociation plasma P11, the holes may sometimes be clogged by deposits 212. Therefore, the clogging of the holes can be suppressed by using the medium-dissociation plasma P12, which will be described below.

[0084] Within the dissociation plasma P12, C4F8 dissociates, for example, into C2F4 and C2F4, and SF6 dissociates, for example, into SF5 and F. Furthermore, in Figure 12 The illustration of SF6 is omitted. In this case, C2F4 is produced as a deposit, and the amount of etchant (F) generated from SF6 is small. C2F4 does not accumulate on mask 211 due to its moderate adhesion coefficient, but forms a deposit (reaction product) 213 in the middle of the sidewalls of the holes (cavities) of the etched film 210. In other words, a precursor for forming a deposit on wafer W is generated within the dissociative plasma P12.

[0085] Within the highly dissociated plasma P13, and Figure 4 Similarly, within the highly dissociated plasma P2 shown, C4F8 dissociates, for example, into C2F4→CF2, or further into CF2→CF and F. Additionally, SF6 dissociates, for example, into SFx and multiple F molecules. Furthermore, in... Figure 12The illustration of SF6 is omitted. In this case, a large amount of etchant (CF2, F) is generated. Furthermore, CF2, due to its low adhesion coefficient, reaches the bottom of the hole (cavity), thus etching progresses. In other words, a precursor for etching the film is generated within the highly dissociative plasma P13.

[0086] [Etching Method]

[0087] Next, the etching method according to the second embodiment will be described. Figure 13 This is a flowchart illustrating an example of the etching process in the second embodiment.

[0088] Following step S2, the control unit 20 supplies the first high-frequency power (bias) for plasma excitation and bias to the base 126 by controlling the high-frequency power supply 128. Here, the applied power (output) of the first high-frequency power is set to a higher value than that when the first plasma is generated. In space S, a mixed gas plasma is generated by supplying the first high-frequency power for plasma excitation and bias to the base 126. That is, in space S, a precursor for forming a deposit is generated using the third plasma (dissociation plasma P12) generated by the first high-frequency power. The wafer W is plasma-treated using the generated plasma. That is, the control unit 20 performs plasma treatment on the wafer W using the third plasma of the process gas generated under the third plasma generation conditions (step S11). The wafer W is exposed to the third plasma to form a deposit (reaction product) 213 on the sidewall of the hole (hole) of the etched film 210. Furthermore, the third plasma is a capacitively coupled plasma (CCP) generated by the first high-frequency power applied to the base 126. Next, the process proceeds to step S3.

[0089] Furthermore, similar to the first embodiment, the control unit 20 may also include the following step between step S3 and step S4, or between step S4 and step S5: stopping the supply of the first high-frequency power and the second high-frequency power to stop plasma generation for a predetermined time. Alternatively, the control unit 20 may execute step S11 immediately after step S3, that is, between step S3 and step S4, instead of executing step S11 immediately before step S3.

[0090] In this second embodiment, by using the dissociation plasma P12, clogging of the aperture can be suppressed, and the middle portion of the aperture's sidewall can be protected. That is, by controlling the degree of dissociation of the process gas according to the level of the first high-frequency power, the generation of a buildup precursor that easily deposits on the upper surface of the mask 211 and a buildup precursor that easily deposits on the mask 211 and the sides of the etched film 210 after etching can be switched, thereby easily forming a protective film conformally. Furthermore, by protecting the portions of the sidewall of the etched aperture that are prone to becoming curved, a state in which a vertical shape can be easily obtained in subsequent etching steps can be achieved.

[0091] [High-frequency power application mode]

[0092] Next, use Figures 14 to 17 This will illustrate the relationship between the high-frequency power application mode and the degree of dissociation of the process gas in the second embodiment. Figures 14 to 17 This is a graph illustrating an example of the relationship between the application mode of high-frequency electricity and the degree of dissociation of the process gas.

[0093] Figure 14 The application mode 270 shown is an example of a mode in which the second high-frequency power (Source) is also "disconnected" simultaneously with the "disconnection" of the first high-frequency power (Bias) in cycle 271, which is a unit cycle, and the output of the first high-frequency power has three stages. That is, application mode 270 includes a process of applying high-frequency power without generating new plasma. In application mode 270, the first high-frequency power is switched between "high," "medium," "low," and "disconnected," and the second high-frequency power is switched between "disconnected" and "connected." Furthermore, in Figure 14 In this context, the height of the curve represents the "high," "medium," and "low" of the first high-frequency power. The first high-frequency power can be set, for example, to: "high" 225W (CW), "medium" 150W (CW), "low" 75W (CW), and "off" 0W. That is, the "medium" of application mode 270 corresponds to the first embodiment. Figure 7 The application mode 230 shown is "High". Furthermore, the "High" range corresponds to the third plasma generation condition, the "Medium" range corresponds to the first plasma generation condition, and the "Low" range corresponds to the second plasma generation condition. Additionally, the second high-frequency power can be set, for example, to "Off" as 0W and "On" as 1100W, which is 1100W (10Hz, 50% duty cycle).

[0094] In application mode 270, curve 272, representing the degree of dissociation of the process gas, is located in the high-dissociation etching region 223 when the second high-frequency power is "on" and the first high-frequency power is "low". When both the first and second high-frequency powers are "off", curve 272 rapidly shifts to the low-dissociation deposition region 224. Subsequently, when the second high-frequency power is "off" and the first high-frequency power is "high", curve 272 becomes a region within the low-dissociation deposition region 224 that maintains a fixed degree of dissociation, close to the high-dissociation etching region 223, i.e., a region of medium dissociation. Figure 14 The "deposition 1" interval in the text. Next, when the second high-frequency power is "off" and the first high-frequency power is "medium", curve 272 becomes a state in the low-dissociation deposition region 224 that further shifts towards the low-dissociation side while maintaining a fixed degree of dissociation. Figure 14 The "Deposition 2" interval in the text. In application mode 270, the medium-dissociation and low-dissociation deposition (deposition) steps and the etching step are repeated by repeating cycle 271.

[0095] Figure 15 The application mode 280 shown is the "high" and "medium" of the first high-frequency power. Figure 14 The application mode 270 shown represents the opposite application modes of the first high-frequency power, "high" and "medium". The first high-frequency power can be set, for example, to "high" 225W (CW), "medium" 150W (CW), "low" 75W (CW), and "off" 0W. Furthermore, the second high-frequency power can be set, for example, to "off" 0W and "on" 1100W, which is 1100W (10Hz, 50% duty cycle).

[0096] In application mode 280, curve 282, representing the degree of dissociation of the process gas, is located in the high-dissociation etching region 223 when the second high-frequency power is "on" and the first high-frequency power is "low". When both the first and second high-frequency powers are "off", curve 282 rapidly shifts to the low-dissociation deposition region 224. Subsequently, when the second high-frequency power is "off" and the first high-frequency power is "medium", curve 282 becomes a region in the low-dissociation deposition region 224 that maintains a fixed degree of dissociation on the low-dissociation side away from the high-dissociation etching region 223. Figure 15 The interval of "Deposition 2" in the middle. Then, when the second high-frequency power is "off" and the first high-frequency power is "high", curve 272 becomes a region that shifts towards the high-dissociation etched region 223 in the low-dissociation deposition region 224, i.e., the medium-dissociation region, and maintains a fixed degree of dissociation. Figure 15The "Deposition 1" interval in the text. In application mode 280, the low-dissociation and medium-dissociation deposition (deposition) steps and the etching step are repeated by repeating cycle 281.

[0097] Figure 16 The application mode 290 shown is relative to Figure 14 The application mode 270 shown is an application mode in which the applied power corresponding to the "high" and "medium" of the first high-frequency power changes from a "high" value to a "medium" value over time. The first high-frequency power can be set, for example, to an initial value of 225W (CW) for "high", a terminal value of 150W (CW) for "medium", 75W (CW) for "low", and 0W for "off". Furthermore, the second high-frequency power can be set, for example, to 0W for "off" and 1100W for "on", which is 1100W (10Hz, 50% duty cycle).

[0098] In application mode 290, curve 292, representing the degree of dissociation of the process gas, is located in the high-dissociation etching region 223 when the second high-frequency power is "on" and the first high-frequency power is "low". When both the first and second high-frequency powers are "off", curve 292 rapidly shifts towards the low-dissociation deposition region 224. Subsequently, when the second high-frequency power is "off" and the first high-frequency power changes from "high" to "medium" over time, the degree of dissociation of curve 292 also changes over time according to the change in the first high-frequency power. In this case, curve 292 becomes a region in the low-dissociation deposition region 224 that is close to the high-dissociation etching region 223, that is, a medium-dissociation region, with a gentler slope and gradually shifts towards the low-dissociation side. Figure 16 The interval from "Deposition 1" to "Deposition 2" is shown in Figure 290. In application mode 290, the accumulation (deposition) steps of medium dissociation and low dissociation, as well as the etching step, are repeated by repeating cycle 291. Furthermore, the interval from "Deposition 1" to "Deposition 2" can be a linear time-varying change or a curved time-varying change represented by a dashed line.

[0099] Figure 17 The application mode 300 shown is the time-varying variation of the first high-frequency power and Figure 16 The application mode 290 shown is an application mode with the first high-frequency power changing over time in the opposite direction. The first high-frequency power can be set, for example, to a terminal value of 225W (CW) for "high", an initial value of 150W (CW) for "medium", 75W (CW) for "low", and 0W for "off". The second high-frequency power can be set, for example, to 0W for "off" and 1100W for "on", which is 1100W (10Hz, 50% duty cycle).

[0100] In application mode 300, curve 302, representing the degree of dissociation of the process gas, is located in the high-dissociation etching region 223 when the second high-frequency power is "on" and the first high-frequency power is "low". When both the first and second high-frequency powers are "off", curve 302 rapidly shifts towards the low-dissociation deposition region 224. Subsequently, when the second high-frequency power is "off" and the first high-frequency power changes from "medium" to "high" over time, the degree of dissociation of curve 302 also changes over time according to the change in the first high-frequency power. In this case, curve 302 becomes a state where the slope reverses in the low-dissociation side of the low-dissociation deposition region 224, away from the high-dissociation etching region 223, and shifts towards the region gradually approaching the high-dissociation etching region 223, that is, the medium-dissociation region. Figure 17 The interval from "Deposition 2" to "Deposition 1" in the model. In application mode 300, the low-dissociation and medium-dissociation deposition (deposition) steps and etching steps are repeated by repeating cycle 301. Furthermore, the interval from "Deposition 2" to "Deposition 1" can not only be a linear time-varying change, but also... Figure 16 Similarly, it is set as a curved change over time.

[0101] In addition, from Figures 14 to 17 In the application modes 270, 280, 290, and 300 shown, by changing one or more of the application power ("high" and "medium") of the first high-frequency power and the processing time, the attachment sites of the deposits 212 and 213 can be controlled from the upper part of the mask 211 to the middle part of the sidewall of the hole of the etched film 210. Furthermore, the time variations in the first and third plasma generation conditions represented in application modes 290 and 300 can also be applied to the first plasma generation conditions in application modes 220, 230, and 240 of the first embodiment.

[0102] In various plasma generation conditions, the first high-frequency power can be controlled, for example, based on the etching depth of the aperture of the etched film 210. In this case, at the start of etching, emphasis is placed on the deposition of deposits onto the upper part of the mask 211, for example, by setting the first high-frequency power to an application power and processing time equivalent to the "high" applied power shown in application mode 230 of the first embodiment. When etching progresses to the middle position of the aperture, emphasis is placed on the deposition of deposits onto the sidewalls of the aperture, for example, by setting the first high-frequency power to the "high" and "medium" applied power and processing time shown in application mode 270. Furthermore, when etching progresses to the deep position of the aperture, emphasis is placed on etching, for example, by lowering the "high" and "medium" applied power shown in application mode 270 and shortening the processing time. In this way, by changing the first high-frequency power and processing time in the low-dissociation and medium-dissociation deposition (deposition) steps and the etching step, the adhesion site of the deposits can be controlled.

[0103] [Variation Example]

[0104] In the embodiments described above, the first plasma (low dissociation plasmas P1 and P11) and the third plasma (medium dissociation plasma P12) are configured as capacitively coupled plasmas (CCP), and the second plasma (high dissociation plasmas P2 and P13) is configured as an inductively coupled plasma (ICP), but this is not a limitation. As a combination of plasma generation methods, a combination of configuring the first and third plasmas as capacitively coupled plasmas (CCP) and the second plasma as a microwave plasma can also be used. Alternatively, the output of the high-frequency power can be relatively varied to use a combination of configuring the first plasma as a low-output inductively coupled plasma (ICP), the third plasma as a medium-output inductively coupled plasma (ICP), and the second plasma as a high-output inductively coupled plasma (ICP). Furthermore, the frequency of the high-frequency power can be relatively varied to use a combination of configuring the first plasma as a low-frequency inductively coupled plasma (ICP), the third plasma as a medium-frequency inductively coupled plasma (ICP), and the second plasma as a high-frequency inductively coupled plasma (ICP). Alternatively, the output of the high-frequency power can be relatively varied to use a combination of capacitively coupled plasma (CCP) with the first plasma set to low output, a capacitively coupled plasma (CCP) with the third plasma set to medium output, and a capacitively coupled plasma (CCP) with the second plasma set to high output. Alternatively, the frequency of the high-frequency power can be relatively varied to use a combination of capacitively coupled plasma (CCP) with the first plasma set to low frequency, a capacitively coupled plasma (CCP) with the third plasma set to medium frequency, and a capacitively coupled plasma (CCP) with the second plasma set to high frequency. In this case, the high-frequency power on the first and third plasma sides is set to LF (Low Frequency), and the high-frequency power on the second plasma side is set to HF (High Frequency). Furthermore, the above-described variations also include combinations of the first and second plasmas (without a third plasma).

[0105] According to the first embodiment, the control unit 20 executes step a), in which a process gas with specific conditions is supplied to a processing container (chamber 101, processing chamber 104) equipped with a mounting stage (base 126) for mounting a workpiece (wafer W) having an etched film and a mask on the etched film. The control unit 20 executes step b), in which the workpiece is plasma-treated by a first plasma of the process gas generated under a first plasma generation condition. The control unit 20 executes step c), in which the workpiece is plasma-treated by a second plasma of the process gas generated under a second plasma generation condition, which is a plasma generation condition that differs from the high-frequency power condition and processing time in the first plasma generation condition but is otherwise identical. The control unit 20 executes step d), in which steps b) and c) are repeated. As a result, high-speed and low-damage etching can be performed compared to gas switching methods.

[0106] Furthermore, according to each embodiment, the second plasma is in a state where the process gas has a higher degree of dissociation compared to the first plasma. As a result, the deposition and etching steps can be repeated.

[0107] Furthermore, according to each embodiment, in step b), a protective film is formed on the workpiece using the reaction products generated by the first plasma. Additionally, in step c), the etchable film is etched using an etchant generated by the second plasma. As a result, the formation of fan-shaped grooves on the sidewalls of the holes can be suppressed.

[0108] Furthermore, according to various embodiments, the second plasma generation condition is a condition that generates a bias potential on the workpiece. As a result, the film to be etched can be etched.

[0109] Furthermore, according to the first embodiment, the control unit 20 executes process e), in which no plasma is generated. Additionally, in process d), processes b), c), and e) are repeated in the order of processes b), c), and e). As a result, the degree of dissociation of the process gas can be rapidly shifted from a high dissociation state to a low dissociation state.

[0110] Furthermore, according to the first embodiment, the conditions for the process gas introduced in step e) are the same as those for the process gas introduced in steps b) and c). As a result, the decrease in productivity caused by the switching of process gases can be suppressed.

[0111] Furthermore, according to various embodiments, the film to be etched is a silicon film, the mask is a silicon-containing film, and the process gas includes fluorocarbon gas or hydrofluorocarbon gas. As a result, the silicon film can be etched.

[0112] Furthermore, according to various embodiments, the process gas also includes a halogen-containing gas. As a result, more etchant can be supplied in a highly dissociated state.

[0113] Furthermore, according to each embodiment, the halogen-containing gas does not contain carbon. As a result, the formation of reaction products can be suppressed under highly dissociated conditions.

[0114] Furthermore, according to various embodiments, the process gas includes: a first gas capable of generating a precursor for forming deposits on the workpiece through plasma-based dissociation; and a second gas capable of generating a precursor for etching the film through plasma-based dissociation. As a result, the formation of fan-shaped grooves at the sidewalls of the aperture can be suppressed.

[0115] Furthermore, according to each embodiment, the first plasma is a capacitively coupled plasma, and the second plasma is an inductively coupled plasma. As a result, high-speed and low-damage etching can be performed compared to gas switching methods.

[0116] Furthermore, according to various embodiments, the first plasma is a capacitively coupled plasma, and the second plasma is a microwave plasma. As a result, high-speed and low-damage etching can be performed compared to gas switching methods.

[0117] Furthermore, according to various embodiments, the first plasma and the second plasma are inductively coupled plasmas or capacitively coupled plasmas, and the frequency of the high-frequency power in the second plasma generation conditions is higher than the frequency of the high-frequency power in the first plasma generation conditions. As a result, the deposition and etching steps can be repeated.

[0118] Furthermore, according to various embodiments, the first plasma and the second plasma are inductively coupled plasmas or capacitively coupled plasmas, and the applied high-frequency power in the second plasma generation conditions is higher than the applied high-frequency power in the first plasma generation conditions. As a result, the deposition and etching steps can be repeated.

[0119] Furthermore, according to various embodiments, the first plasma generation conditions include varying the applied power, which serves as a high-frequency power condition, over time. As a result, the extent of the protective film formed by the reaction products (accumulation material) can be controlled.

[0120] Furthermore, according to each embodiment, the high-frequency power conditions and processing time in the first and second plasma generation conditions are adjusted based on the depth of the etched film. As a result, the formation of fan-shaped grooves on the sidewalls of the aperture can be suppressed.

[0121] Furthermore, according to the second embodiment, the control unit 20 executes step f), in which the workpiece is subjected to plasma treatment using a third plasma of process gas generated under a third plasma generation condition. The third plasma generation condition is a plasma generation condition that differs from the first and second plasma generation conditions in terms of high-frequency power and processing time, but is otherwise identical. Additionally, step f) is executed at least once before or immediately after step b). As a result, clogging of the orifice can be suppressed, and the middle portion of the orifice's sidewall can be protected.

[0122] Furthermore, according to the second embodiment, the third plasma has a higher degree of dissociation of the process gas compared to the first plasma, and a lower degree of dissociation of the process gas compared to the second plasma. As a result, clogging of the orifice can be suppressed, and the middle portion of the orifice's sidewall can be protected.

[0123] Furthermore, according to the second embodiment, in step f), a protective film is formed on the workpiece using reaction products generated by the third plasma. As a result, the middle portion of the sidewall of the hole can be protected.

[0124] Furthermore, according to the second embodiment, a protective film is formed on the upper surface of the mask using reaction products generated by the first plasma, and a protective film is formed on the side surfaces of the mask and the etched film using reaction products generated by the third plasma. As a result, protection can be provided from the upper surface of the mask to the middle portion of the sidewall of the hole.

[0125] Furthermore, according to the second embodiment, the third plasma is an inductively coupled plasma or a capacitively coupled plasma, and the frequency of the high-frequency power in the third plasma generation conditions is higher than the frequency of the high-frequency power in the first plasma generation conditions and lower than the frequency of the high-frequency power in the second plasma generation conditions. As a result, both deposition and etching steps can be repeated.

[0126] Furthermore, according to the second embodiment, the third plasma is an inductively coupled plasma or a capacitively coupled plasma. The applied high-frequency power in the third plasma generation conditions is higher than the applied high-frequency power in the first plasma generation conditions, but lower than the applied high-frequency power in the second plasma generation conditions. As a result, both deposition and etching steps can be repeated.

[0127] Furthermore, according to the second embodiment, the high-frequency power conditions and processing time in the first, second, and third plasma generation conditions are adjusted based on the depth of the etched film. As a result, a vertical shape is easily obtained on the sidewalls of the hole.

[0128] Furthermore, according to the second embodiment, the first plasma generation conditions and the third plasma generation conditions include varying the applied power, which is a high-frequency power condition, over time. As a result, the extent of the protective film formed by the reaction products (accumulation material) can be controlled.

[0129] It should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. The above embodiments may be omitted, substituted, or modified in various ways without departing from the scope and spirit of the appended claims.

[0130] Furthermore, in the embodiments described above, inductively coupled plasma (ICP), capacitively coupled plasma (CCP), and microwave plasma have been cited as plasma sources, but the method is not limited to these. For example, any plasma source such as magnetron plasma can also be used as a plasma source.

[0131] Furthermore, in the embodiments described above, silicon films are listed as the films to be etched, but the method is not limited to this. For example, it can be applied to etching of various silicon-containing films such as silicon oxide films and silicon nitride films as the films to be etched.

[0132] Explanation of reference numerals in the attached figures

[0133] 10: Main body; 20: Control unit; 100: Plasma processing device; 101: Chamber; 103: Antenna chamber; 104: Processing chamber; 115, 128: High-frequency power supply; 120: Gas supply mechanism; 124: Gas supply pipe; 126: Base; 131: Electrostatic holding disk; S: Space; W: Wafer

Claims

1. A substrate processing method, which is a substrate processing method in a substrate processing apparatus, the substrate processing method comprising the following steps: Step a) Supplying a process gas under specific conditions to a processing container equipped with a stage for holding a workpiece having an etched film and a mask on the etched film. Step b) involves plasma treatment of the workpiece using a first plasma of the process gas generated under the first plasma generation conditions. Step c) The object to be processed is subjected to plasma treatment by the second plasma of the process gas generated under the second plasma generation conditions. The second plasma generation conditions are different from the high-frequency power conditions and processing time in the first plasma generation conditions, but the other conditions are the same. The state of the second plasma is that the process gas has a higher degree of dissociation than the state of the first plasma. Process e) does not generate plasma; as well as Step d) is performed by repeating steps b), c), and e in the order of steps b), c), and e).

2. The substrate processing method according to claim 1, characterized in that, In step b), a protective film is formed on the workpiece using the reaction products generated by the first plasma. In step c), the etched film is etched using an etchant generated by the second plasma.

3. The substrate processing method according to claim 1 or 2, characterized in that, The second plasma generation condition is the condition that generates a bias potential on the object being treated.

4. The substrate processing method according to claim 1, characterized in that, The conditions under which the process gas is introduced in step e) are the same as those under which the process gas is introduced in steps b) and c).

5. The substrate processing method according to claim 1 or 2, characterized in that, The etched film is a silicon film. The mask is a silicon-containing film. The process gas contains fluorocarbon gas or hydrofluorocarbon gas.

6. The substrate processing method according to claim 5, characterized in that, The process gas also includes halogen-containing gases.

7. The substrate processing method according to claim 6, characterized in that, The halogen-containing gas does not contain carbon.

8. The substrate processing method according to claim 1 or 2, characterized in that, The process gas includes: a first gas capable of generating a precursor for forming an accumulation on the workpiece through plasma-based dissociation; and a second gas capable of generating a precursor for etching the etched film through plasma-based dissociation.

9. The substrate processing method according to claim 1 or 2, characterized in that, The first plasma and the second plasma are inductively coupled plasmas or capacitively coupled plasmas. The frequency of the high-frequency power in the second plasma generation condition is higher than the frequency of the high-frequency power in the first plasma generation condition.

10. The substrate processing method according to claim 1 or 2, characterized in that, The first plasma and the second plasma are inductively coupled plasmas or capacitively coupled plasmas. The applied high-frequency power in the second plasma generation condition is higher than the applied high-frequency power in the first plasma generation condition.

11. The substrate processing method according to claim 1 or 2, characterized in that, The first plasma generation condition includes varying the applied power, which is a condition for the high-frequency power, over time.

12. The substrate processing method according to claim 1 or 2, characterized in that, The high-frequency power conditions and the processing time in the first plasma generation conditions and the second plasma generation conditions are adjusted according to the depth of the etched film after etching.

13. A substrate processing method, which is a substrate processing method in a substrate processing apparatus, the substrate processing method comprising the following steps: Step a) Supplying a process gas under specific conditions to a processing container equipped with a stage for holding a workpiece having an etched film and a mask on the etched film. Step b) involves plasma treatment of the workpiece using a first plasma of the process gas generated under the first plasma generation conditions. Step c) involves plasma treatment of the workpiece using a second plasma generated by the process gas under a second plasma generation condition. The second plasma generation condition is the same as the first plasma generation condition but different in terms of high-frequency power and processing time. Step d), repeating steps b) and c); and Step f) involves plasma treatment of the workpiece using a third plasma of the process gas generated under third plasma generation conditions. These third plasma generation conditions differ from the first and second plasma generation conditions in terms of the high-frequency power and processing time, while other conditions remain the same. Furthermore, the third plasma exhibits a higher degree of dissociation of the process gas compared to the first plasma, and a lower degree of dissociation compared to the second plasma. The process f is performed at least in either the process immediately before or immediately after the process b).

14. The substrate processing method according to claim 13, characterized in that, In step f), a protective film is formed on the workpiece using the reaction products generated by the third plasma.

15. The substrate processing method according to claim 14, characterized in that, The protective film is formed on the upper surface of the mask using the reaction products generated by the first plasma. The protective film is formed on the sides of the mask and the sides of the etched film after etching using the reaction products generated by the third plasma.

16. The substrate processing method according to any one of claims 13 to 15, characterized in that, The third plasma is either an inductively coupled plasma or a capacitively coupled plasma. The frequency of the high-frequency power in the third plasma generation condition is higher than the frequency of the high-frequency power in the first plasma generation condition and lower than the frequency of the high-frequency power in the second plasma generation condition.

17. The substrate processing method according to any one of claims 13 to 15, characterized in that, The third plasma is either an inductively coupled plasma or a capacitively coupled plasma. The applied high-frequency power in the third plasma generation condition is higher than the applied high-frequency power in the first plasma generation condition and lower than the applied high-frequency power in the second plasma generation condition.

18. The substrate processing method according to any one of claims 13 to 15, characterized in that, The conditions of the high-frequency power and the processing time in the first plasma generation conditions, the second plasma generation conditions and the third plasma generation conditions are adjusted according to the depth of the etched film.

19. The substrate processing method according to any one of claims 13 to 15, characterized in that, The first plasma generation condition and the third plasma generation condition include changing the applied power, which is a condition for the high-frequency power, over time.

20. A substrate processing apparatus, characterized in that, have: Handling containers; A stage, disposed within the processing container, for holding a workpiece having an etched film and a mask on the etched film; and Control Department Wherein, a) the control unit is configured to control the substrate processing apparatus to supply process gas of specific conditions to the processing container. b) The control unit is configured to control the substrate processing apparatus to perform plasma processing on the workpiece using a first plasma of the process gas generated under the first plasma generation conditions. c) The control unit is configured to control the substrate processing apparatus to perform plasma processing on the workpiece using a second plasma of the process gas generated under a second plasma generation condition. The second plasma generation condition is a plasma generation condition that differs from the high-frequency power condition and processing time in the first plasma generation condition, but is otherwise identical. Furthermore, the state of the second plasma is such that the process gas has a higher degree of dissociation compared to the state of the first plasma. e) The control unit is configured to control the substrate processing apparatus to prevent the generation of plasma. d) The control unit is configured to control the substrate processing apparatus to repeat b), c), and e) in the order of b), c), and e).

21. A substrate processing apparatus, characterized in that, have: Handling containers; A stage, disposed within the processing container, for holding a workpiece having an etched film and a mask on the etched film; and Control Department Wherein, a) the control unit is configured to control the substrate processing apparatus to supply process gas of specific conditions to the processing container. b) The control unit is configured to control the substrate processing apparatus to perform plasma processing on the workpiece using a first plasma of the process gas generated under the first plasma generation conditions. c) The control unit is configured to control the substrate processing apparatus to perform plasma processing on the workpiece using a second plasma generated by the process gas under a second plasma generation condition, wherein the second plasma generation condition is a plasma generation condition that differs from the high-frequency power condition and processing time in the first plasma generation condition, but is otherwise identical. d) The control unit is configured to control the substrate processing apparatus to repeat steps b) and c). f) The control unit is configured to control the substrate processing apparatus to perform plasma processing on the workpiece using a third plasma of the process gas generated under a third plasma generation condition. The third plasma generation condition is a plasma generation condition that differs from the high-frequency power condition and processing time in the first and second plasma generation conditions, but is otherwise identical. Furthermore, the state of the third plasma is such that the process gas has a higher degree of dissociation than the state of the first plasma, and a lower degree of dissociation than the state of the second plasma. f) is performed on at least one of the two terms: immediately before b) and immediately after b).

Images