Substrate processing method and substrate processing apparatus

Abstract

The present application provides a substrate processing method and a substrate processing apparatus, which can achieve at least one of improving the productivity of etching and suppressing shape abnormality of a recess formed by etching. The substrate processing method includes a step a1), a step a2), a step a3), and a step a4). In the step a1), a substrate including a silicon-containing film is provided into a chamber. In the step a2), a processing gas including an HF gas is supplied into the chamber. In the step a3), the silicon-containing film is etched by a plasma generated from the processing gas to form a recess in the silicon-containing film. In the step a4), a control is performed so that the partial pressure of the HF gas decreases as the aspect ratio of the recess increases.

Description

Technical Field

[0001] Various aspects and embodiments of this disclosure relate to a substrate processing method and a substrate processing apparatus. Background Technology

[0002] For example, Patent Document 1 discloses a technique for etching silicon-containing films using plasma.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-39310 Summary of the Invention

[0006] The problem the invention aims to solve

[0007] This disclosure provides a substrate processing method and a substrate processing apparatus capable of improving etching productivity and suppressing at least one of the shape anomalies of recesses formed by etching.

[0008] Solution for solving the problem

[0009] One aspect of this disclosure is a substrate processing method, including steps a1), a2), a3), and a4). In step a1), a substrate containing a silicon-containing film is provided into a chamber. In step a2), a process gas containing HF gas is supplied into the chamber. In step a3), the silicon-containing film is etched using plasma generated from the process gas to form a recess in the silicon-containing film. In step a4), control is performed so that the partial pressure of the HF gas decreases as the aspect ratio of the recess increases.

[0010] The effects of the invention

[0011] According to various aspects and embodiments of this disclosure, it is possible to achieve at least one of improving etching productivity and suppressing shape anomalies in the recesses formed by etching. Attached Figure Description

[0012] Figure 1 This is a diagram illustrating an example of a plasma processing apparatus according to one embodiment of the present disclosure.

[0013] Figure 2 This is a diagram showing an example of a cross-section of a substrate being etched.

[0014] Figure 3A This is a diagram showing an example of a cross-section of a recess when there is a lot of etchant.

[0015] Figure 3B This is a diagram showing an example of a cross-section of a recess when there is little etchant.

[0016] Figure 4 This is a graph illustrating an example of the relationship between processing time and etching rate.

[0017] Figure 5 This is a diagram illustrating an example of the relationship between the depth of the recess and the etching rate.

[0018] Figure 6 This is a diagram illustrating the relationship between the vapor pressure of the reaction byproducts and the depth-to-width ratio of the recess.

[0019] Figure 7 This is a flowchart illustrating an example of a substrate processing method in one embodiment of the present disclosure.

[0020] Figure 8 This is a diagram illustrating an example of the change in the partial pressure of the etchant.

[0021] Figure 9 This is a flowchart illustrating other examples of substrate processing methods.

[0022] Figure 10 These are other examples of graphs illustrating changes in the partial pressure of the etchant.

[0023] Figure 11 These are other examples of graphs illustrating changes in the partial pressure of the etchant. Detailed Implementation

[0024] Hereinafter, embodiments of the disclosed substrate processing method and substrate processing apparatus will be described in detail based on the accompanying drawings. However, the disclosed substrate processing method and substrate processing apparatus are not limited by the following embodiments.

[0025] Furthermore, during etching, the etchant reacts with the target film. A portion of the target film that reacts with the etchant transforms into volatile reaction byproducts and is removed, thereby forming a recess in the target film. However, when the amount of etchant is high, at the bottom of the recess, the rate of reaction byproduct formation is faster than the rate of evaporation. Sometimes, the reaction byproducts cannot evaporate and deposit at the bottom of the recess. When reaction byproducts deposit at the bottom of the recess, they hinder the reaction between the etchant and the target film, thus reducing the etching rate. As the etching rate continues to decrease, etching eventually stops.

[0026] Additionally, when the amount of etchant is excessive, the bottom tip of the recess sometimes becomes tapered. When the bottom tip of the recess becomes tapered, it can sometimes cause the recess to bend in the depth direction. When the recess is formed in a bent manner, it can lead to undesirable conditions such as it connecting with adjacent recesses.

[0027] On the other hand, when the amount of etchant is small, the cross-section at the bottom of the recess becomes rectangular, but sometimes the etching rate becomes low. When the etching rate is low, the sidewalls of the recess are exposed to the etchant for a long time, so sometimes bending occurs on the sidewalls of the recess.

[0028] Therefore, this disclosure provides a technique that can achieve at least one of improving etching productivity and suppressing shape anomalies of the recesses formed by etching.

[0029] [Structure of the plasma processing device 100]

[0030] The following describes a structural example of the plasma processing apparatus 100. Figure 1 This diagram illustrates an example of a plasma processing apparatus 100 according to one embodiment of the present disclosure. The plasma processing apparatus 100 is a capacitively coupled plasma processing apparatus, including an apparatus body 1 and a control unit 2. The plasma processing apparatus 100 is an example of a substrate processing apparatus. The apparatus body 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. Additionally, the apparatus body 1 includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet includes a spray head 13. The substrate support 11 is disposed within the plasma processing chamber 10. The spray head 13 is disposed above the substrate support 11. In one embodiment, the spray head 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10.

[0031] The plasma processing chamber 10 has a plasma processing space 10s defined by a spray head 13, a side wall 10a of the plasma processing chamber 10, and a substrate support 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for discharging gas from the plasma processing space 10s. The side wall 10a is grounded. The spray head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10. Furthermore, a light sensor 114 capable of measuring the intensity of light of various wavelengths in the plasma within the plasma processing chamber 10 through a quartz window 113 can be installed in the plasma processing apparatus 100.

[0032] The substrate support portion 11 includes a main body portion 111 and an annular assembly 112. The main body portion 111 has a central region for supporting the substrate W, namely a substrate support surface 111a, and an annular region for supporting the annular assembly 112, namely an annular support surface 111b. The substrate W is sometimes also referred to as a wafer. In top view, the annular support surface 111b of the main body portion 111 surrounds the substrate support surface 111a of the main body portion 111. The substrate W is disposed on the substrate support surface 111a of the main body portion 111, and the annular assembly 112 is disposed on the annular support surface 111b of the main body portion 111 in such a way that it surrounds the substrate W on the substrate support surface 111a of the main body portion 111.

[0033] In one embodiment, the main body 111 includes an electrostatic chuck and a base. 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 is a substrate support surface 111a.

[0034] The annular assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring. Additionally, the substrate support 11 may include a temperature regulating module (not shown), configured to regulate at least one of the electrostatic chuck 1110, the annular assembly 112, and the substrate W to a target temperature. The temperature regulating 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 in the flow path. Furthermore, the substrate support 11 may include a heat transfer gas supply section configured to supply heat transfer gas between the substrate W and the substrate support surface 111a.

[0035] The spray head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The spray head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of 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 plurality of gas inlets 13c. Additionally, the spray head 13 includes a conductive member. The conductive member of the spray head 13 functions as an upper electrode. Furthermore, in addition to the spray head 13, the gas inlet may also include one or more side gas injectors (SGIs), which are mounted on one or more openings formed in the sidewall 10a.

[0036] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the spray head 13 via a corresponding flow controller 22. Each flow controller 22 may, for example, include a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include one or more flow modulation devices for modulating or pulsedizing the flow rate of the at least one process gas.

[0037] The power supply 30 includes an RF (Radio Frequency) power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one of a source RF signal and a bias RF signal to a conductive member of the substrate support 11, a conductive member of the spray head 13, or both. This generates plasma from at least one processing gas supplied to the plasma processing space 10s. Specifically, in one embodiment, the conductive member of the substrate support 11 or the conductive member of the spray head 13 can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases within the plasma processing chamber 10. Furthermore, by providing a bias RF signal to the conductive member of the substrate support 11, a bias potential can be generated on the substrate W, attracting ionic components from the formed plasma to the substrate W.

[0038] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is coupled to, or coupled to, a conductive member of the substrate support 11 or a conductive member of the spray head 13 via at least one impedance matching circuit. The first RF generation unit 31a is configured to generate a source RF signal for generating plasma. The source RF signal may be referred to as source RF power. In one embodiment, the source RF signal has a frequency in the range of 13MHz to 150MHz. In one embodiment, the first RF generation unit 31a may be configured to generate multiple source RF signals with different frequencies. The generated one or more source RF signals are provided to, or to, a conductive member of the substrate support 11 or a conductive member of the spray head 13.

[0039] The second RF generation unit 31b is coupled to the conductive member of the substrate support portion 11 via at least one impedance matching circuit. The second RF generation unit 31b is configured to generate a bias RF signal. The bias RF signal can be referred to as bias RF power. In one embodiment, the bias RF signal has a frequency lower than that of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 400 kHz to 13.56 MHz. In one embodiment, the second RF generation unit 31b can be configured to generate multiple bias RF signals with different frequencies. The generated one or more bias RF signals are provided to the conductive member of the substrate support portion 11. In addition, in various embodiments, at least one of the source RF signal and the bias RF signal can be pulsed.

[0040] Additionally, the power supply 30 may include a DC (Direct Current) power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generating unit 32a and a second DC generating unit 32b. In one embodiment, the first DC generating unit 32a is connected to a conductive member of the substrate support 11 and is configured to generate a first DC signal. The generated first DC signal is applied to the conductive member of the substrate support 11. In other embodiments, the first DC signal may be applied to other electrodes, such as electrode 1110a in the electrostatic chuck 1110. In one embodiment, the second DC generating unit 32b is connected to a conductive member of the spray head 13 and is configured to generate a second DC signal. The generated second DC signal is applied to the conductive member of the spray head 13. In various embodiments, at least one of the first DC signal and the second DC signal may be pulsed. In addition, a first DC generating unit 32a and a second DC generating unit 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided to replace the second RF generating unit 31b.

[0041] The exhaust system 40 can be connected, for example, to a gas outlet 10e located 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 within the plasma processing space 10s is adjusted via the pressure regulating valve. The vacuum pump is a turbomolecular pump, a dry pump, or a combination thereof.

[0042] The control unit 2 processes computer-executable commands that cause the device body 1 to perform the various processes described herein. The control unit 2 can be configured to control various elements of the device body 1 to perform the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the device body 1. The control unit 2 may, for example, include a computer 2a. The computer 2a may, for example, include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 can be configured to perform various control actions based on programs stored in the storage unit 2a2. The processing unit 2a1 may include a CPU (Central Processing Unit). The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or combinations thereof. The communication interface 2a3 communicates with the device body 1 via a communication line such as a LAN (Local Area Network).

[0043] Here, it is explained that by Figure 1 Etching is performed using the plasma processing apparatus 100 illustrated in the diagram. In the etching process, for example, a plasma processing apparatus such as... Figure 2 The substrate W shown has a silicon-containing film 50, which is the film to be etched, and a mask 51 formed on the silicon-containing film 50. An opening 51a is formed in the mask 51.

[0044] In this embodiment, the silicon-containing film 50 includes a silicon oxide film and a silicon nitride film. Alternatively, the silicon-containing film 50 may be a film comprising a silicon oxide film and a polycrystalline silicon film, or a film comprising a silicon oxide film, a silicon nitride film, and a polycrystalline silicon film. Furthermore, the silicon-containing film 50 may be a silicon oxide film, a multilayer film of silicon oxide and silicon nitride, or a multilayer film of silicon oxide and polycrystalline silicon.

[0045] In this embodiment, a mask 51 is disposed on a silicon-containing film 50. The mask 51 is formed of a material having an etching rate lower than that of the silicon-containing film 50. The mask 51 can be formed of an organic material. That is, the mask 51 can contain carbon. For example, the mask 51 can be formed of an amorphous carbon film, a photoresist film, or a spin-coated carbon film (SOC film). Alternatively, the mask 51 can be formed of a silicon-containing film such as a silicon-containing antireflective film. Alternatively, the mask 51 can be a metal-containing mask formed of a metal-containing material such as titanium nitride, tungsten, or tungsten carbide.

[0046] In etching, Figure 2The illustrated substrate W is moved into the plasma processing chamber 10 and placed on the substrate support portion 11. Furthermore, by supplying voltage to the electrostatic chuck of the main body portion 111, the substrate W is held adsorbed on the substrate support surface 111a. Moreover, the gas inside the plasma processing chamber 10 is exhausted by the exhaust system 40, and processing gas is supplied to the plasma processing chamber 10 from the gas supply portion 20 via the spray head 13. In this embodiment, the processing gas includes HF gas. In this embodiment, HF gas is an example of an etchant.

[0047] Furthermore, the processing gas may contain a carbon-containing gas. As such a carbon-containing gas, at least one gas selected from the group consisting of fluorocarbon compound gases (CF-based gases) and hydrofluorocarbon gases (CHF-based gases) is preferred. As a CF-based gas, at least one gas selected from the group consisting of CF4, C2F2, C2F4, C3F8, C4F6, C4F8, and C5F8 can be used. In one example, the CF-based gas is C4F6 or C4F8. Additionally, as CHF-based gases, for example, gases derived from CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F4, C3H2F6, C3H3F5, C4H2F6, C4H2F8, C4H5F5, C5H2F6, and C5H2F can be used. 10 At least one gas selected from the group consisting of C5H3F7 gas and other gases. In one example, the CHF-based gas is at least one gas selected from the group consisting of C3H2F4 gas, C3H2F6 gas, C4H2F6 gas, and C4H2F8 gas. By including such a gas in the process gas, a carbon-containing deposit is formed on the surface of the mask 51, suppressing the etching of the mask 51. Therefore, the ratio (selectivity ratio) of the etching rate of the silicon-containing film to the etching rate of the mask 51 can be improved.

[0048] Additionally, the processing gas may include at least one gas selected from the group consisting of phosphorus-containing gases, sulfur-containing gases, and boron-containing gases. For example, phosphorus-containing gases may be selected from PF3, PF5, POF3, HPF6, PCl3, PCl5, POCl3, PBr3, PBr5, POBr3, PI3, and P4O. 10At least one gas selected from the group consisting of P4O8, P4O6, PH3, Ca3P2, H3PO4, and Na3PO4. As a sulfur-containing gas, at least one gas selected from the group consisting of SF6, SO2, and COS can be used, for example. As a boron-containing gas, at least one gas selected from the group consisting of BCl3, BF3, BBr3, and B2H6 can be used, for example. These gases are deposited on the sidewalls of the recess formed by etching to form a protective film. Therefore, bending in the recess can be suppressed.

[0049] In addition, the processed gas may also include halogen-containing gases. Halogen-containing gases may be carbon-free. Halogen-containing gases can be fluorine-containing gases or gases containing other halogen elements besides fluorine. Fluorine-containing gases may include, for example, NF3, SF6, and BF3 gases. Gases containing other halogen elements besides fluorine may be at least one gas selected from the group consisting of chlorine-containing gases, bromine-containing gases, and iodine-containing gases. Chlorine-containing gases may include, for example, Cl2, HCl, SiCl2, SiCl4, CCl4, SiH2Cl2, Si2Cl6, CHCl3, CH2Cl2, CH3Cl, SO2Cl2, and BCl3 gases. Bromine-containing gases may include, for example, Br2, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, and BBr3 gases. Iodine-containing gases include, for example, HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3. Chemical species generated from these halogen-containing molecules are used to control the shape of the recesses formed by plasma etching.

[0050] Additionally, the processing gas may contain an oxygen-containing gas. The oxygen-containing gas may be, for example, at least one gas selected from the group consisting of O2, CO, CO2, H2O, and H2O2. In one example, the processing gas includes an oxygen-containing gas other than H2O, i.e., at least one gas selected from the group consisting of O2, CO, CO2, and H2O2. The oxygen-containing gas can suppress clogging of the opening 51a of the mask 51 during etching.

[0051] Furthermore, the processing gas can include inert gases. Inert gases, for example, can include rare gases such as Ar, Kr, and Xe, in addition to nitrogen.

[0052] Furthermore, a source RF signal is provided from the RF power supply 31 to the conductive members of the substrate support 11 or the conductive members of the spray head 13. This generates plasma from the process gas within the plasma processing chamber 10. Additionally, a bias RF signal is provided from the RF power supply 31 to the conductive members of the substrate support 11. This generates a bias potential on the substrate W, attracting ionic components from the plasma to the substrate W, and forming a recess 52 on the silicon-containing film 50 along the opening 51a formed in the mask 51. Alternatively, a first DC signal can be applied from the DC power supply 32 to the conductive members of the substrate support 11 instead of the bias RF signal from the RF power supply 31. Furthermore, a second DC signal can be applied from the DC power supply 32 to the conductive members of the spray head 13.

[0053] Here, with a high amount of etchant (i.e., a high partial pressure), a high etching rate can be achieved in the initial stage of etching. However, with a high partial pressure of the etchant, the rate of formation of reaction byproducts at the bottom of the recess 52 is faster than the rate of volatilization. Therefore, the reaction byproducts are difficult to volatilize, for example... Figure 3A As shown, reaction byproduct 53 is deposited at the bottom of the recess 52. When reaction byproduct 53 is deposited at the bottom of the recess 52, the reaction between the etchant and the silicon-containing film 50 is hindered by reaction byproduct 53, resulting in a decrease in the etching rate. When the etching rate continues to decrease, etching may eventually stop.

[0054] Additionally, when the partial pressure of the etchant is high, for example, Figure 3A As shown, the bottom front end of the recess 52 tapers. When the bottom front end of the recess 52 tapers, it sometimes causes the recess 52 to bend in the depth direction. When the recess 52 is formed in a bent manner, it can sometimes cause undesirable situations such as it connecting with adjacent recesses 52.

[0055] On the other hand, when the partial pressure of the etchant is low, for example, Figure 3B As shown, the bottom cross-section of the recess 52 is rectangular, but due to the small amount of etchant, the etching rate is low. When the etching rate is low, the sidewalls of the recess 52 are exposed to the etchant for a long time. Thus, for example... Figure 3B As shown, lateral etching progresses on the sidewalls of recess 52, sometimes promoting what is known as bending.

[0056] [Experimental Results]

[0057] Next, experiments were conducted to measure the changes in etching rate under various etching conditions. Figure 4 This is a graph illustrating an example of the relationship between processing time and etching rate. Figure 5 This is a diagram illustrating an example of the relationship between the depth of the recess 52 and the etching rate. Figure 4 and Figure 5 The main treatment conditions in Experiments 1 through 4 are shown below.

[0058] [Experiment 1]

[0059] Pressure inside plasma processing chamber 10: 27 mTor

[0060] Processing gas: HF gas

[0061] Source RF signal: 40MHz, 4500W

[0062] Bias RF signal: 400kHz, 7000W

[0063] Temperature of substrate W: -40℃

[0064] [Experiment 2]

[0065] Pressure within plasma processing chamber 10: 10 mTorr

[0066] Processing gas: HF gas

[0067] Source RF signal: 40MHz, 4500W

[0068] Bias RF signal: 400kHz, 7000W

[0069] Temperature of substrate W: -40℃

[0070] [Experiment 3]

[0071] Pressure inside plasma processing chamber 10: 27 mTorr

[0072] Gases processed: HF, Ar, O2

[0073] Source RF signal: 40MHz, 4500W

[0074] Bias RF signal: 400kHz, 7000W

[0075] Temperature of substrate W: -40℃

[0076] [Experiment 4]

[0077] Pressure inside plasma processing chamber 10: 27 mTorr

[0078] Gases processed: HF gas, BCl3 gas, C4F8 gas

[0079] Source RF signal: 40MHz, 4500W

[0080] Bias RF signal: 400kHz, 7000W

[0081] Temperature of substrate W: -40℃

[0082] Reference Figure 4 and Figure 5 Under the condition of high partial pressure of HF gas as etchant (Experiment 1), although a high etching rate was achieved in the initial stage of etching, the etching rate decreased sharply as etching progressed. That is, under the condition of high partial pressure of etchant, the etching rate decreased sharply with the increase of the depth-to-width ratio of the recess 52.

[0083] On the other hand, under the condition of reducing the partial pressure of HF gas by lowering the pressure inside the plasma processing chamber 10 (Experiment 2), the etching rate was lower in the initial stage of etching compared to the conditions in Experiment 1, but the decrease in etching rate was suppressed compared to the conditions in Experiment 1. Furthermore, under the condition of reducing the partial pressure of HF gas by adding other gases besides HF gas as an etchant to the processing gas (Experiment 3), and under the condition of reducing the partial pressure of HF gas by adding a gas with the effect of removing HF gas (Experiment 4), the decrease in etching rate as etching progresses was also suppressed compared to the conditions in Experiment 1. That is, under the condition of low etchant partial pressure (Experiments 2-4), although the etching rate was lower in the initial stage of etching compared to the conditions in Experiment 1, the decrease in etching rate as the aspect ratio of the recess 52 increased was suppressed. Moreover, a gas with the effect of removing HF gas refers to a gas that reacts with elements contained in HF gas to generate compounds different from HF gas, thereby removing or reducing HF gas inside the plasma processing chamber 10.

[0084] [Relationship between the vapor pressure of reaction byproduct 53 and the depth-to-width ratio of recess 52]

[0085] Figure 6 This is a diagram illustrating an example of the relationship between the vapor pressure of reaction byproduct 53 and the aspect ratio of the recess 52. For example... Figure 6 As shown, when the flow rate of reaction byproduct 53 is set to Γ By When the position in the depth direction of the recess 52 is set as AR, the pressure p(AR) in the recess 52 is expressed as in the following formula (1).

[0086]

Number 1

[0087]

[0088] In the above equation (1), P0 represents the pressure inside the plasma processing chamber 10, m represents the mass of the etchant molecules, k represents the Boltzmann constant, and T represents the temperature of the substrate W.

[0089] As can be clearly seen from equation (1) above, the pressure p(AR) within the recess 52 is proportional to the depth AR of the recess 52. That is, the pressure p(AR) at the bottom of the recess 52 is proportional to the depth AR of the recess 52. max ) is proportional to the depth-to-width ratio of the recess 52.

[0090] At the bottom of the recess 52, the generated reaction byproduct 53 volatilizes, thereby advancing the etching along the depth direction of the recess 52. At the bottom of the recess 52, in order for the generated reaction byproduct 53 to volatilize, the vapor pressure P of the reaction byproduct 53 needs to be reduced. d The pressure p(AR) at the bottom of the concave portion 52 max Large. That is, in order for etching in the depth direction of the recess 52 to progress, the vapor pressure P of the reaction byproduct 53 is large. d The pressure p(AR) at the bottom of the recess 52 max It needs to satisfy the following relationship (2).

[0091]

Number 2

[0092]

[0093] When the above equation (2) is transformed, it becomes the following equation (3).

[0094]

Number 3

[0095]

[0096] The flow rate Γ of reaction byproduct 53 By It is proportional to the etching rate, so according to the above equation (3), the following can be known.

[0097] 1. When the etching rate is high, the pressure inside the recess 52 increases.

[0098] 2. When the pressure p(AR) within the recess 52 exceeds the vapor pressure P of the reaction byproduct 53 d At that time, reaction byproduct 53 no longer volatilizes.

[0099] 3. Etching stops when the reaction byproduct 53 ceases to volatilize. (Physical sputtering continues.)

[0100] Furthermore, the following conclusions were reached.

[0101] • The flow rate Γ of reaction byproduct 53 By The upper limit is determined by the vapor pressure P of reaction byproduct 53. d The aspect ratio of the recess 52 is determined by the depth.

[0102] • The flow rate Γ of reaction byproduct 53 By The upper limit of the etching rate is proportional to the etching rate, therefore it is also determined by the vapor pressure P of the reaction byproduct 53.d The aspect ratio of the recess 52 is determined by the depth.

[0103] The lower the temperature of the substrate W, the lower the etching rate.

[0104] The higher the pressure inside the plasma processing chamber 10, the lower the etching rate.

[0105] Therefore, in the initial stage of etching with a small aspect ratio, it is preferable to increase the etching rate by increasing the partial pressure of the etchant. Furthermore, as the aspect ratio increases, the reaction byproduct 53 becomes less volatile, resulting in a decrease in the etching rate. Therefore, it is preferable to promote the volatilization of the reaction byproduct 53 by reducing the partial pressure of the etchant, thereby suppressing the decrease in the etching rate. This allows for an overall improvement in the productivity of etching for forming the recess 52.

[0106] Additionally, by reducing the partial pressure of the etchant, for example... Figure 3B As shown, the bottom cross-section of the reaction byproduct 53 can be formed into a rectangular shape. This allows the shape of the recess 52 to approximate a predetermined shape. Furthermore, by reducing the partial pressure of the etchant, the taper of the bottom tip of the recess 52 can be suppressed, thus preventing the recess 52 from forming in a bent manner in the depth direction.

[0107] Furthermore, in the initial stage of etching with a small aspect ratio, the etching rate is increased by increasing the partial pressure of the etchant, thereby shortening the time until the recess 52 of the desired depth is formed. This shortens the time the sidewalls of the recess 52 are exposed to the etchant, thus suppressing the lateral expansion of the sidewalls of the recess 52.

[0108] Four methods are considered as ways to reduce the partial pressure of the etchant. The first method is to reduce the partial pressure of the etchant by lowering the pressure within the plasma processing chamber 10. The second method is to add a diluent gas into the plasma processing chamber 10. Preferably, the diluent gas is a gas that does not contribute to etching; for example, rare gases such as argon and inactive gases such as nitrogen can be considered. This also reduces the partial pressure of the etchant within the plasma processing chamber 10. Furthermore, in the second method, the pressure within the plasma processing chamber 10 can be kept constant or not when adding the diluent gas.

[0109] The third method is to supply a reactive gas with the function of removing etchant into the plasma processing chamber 10. More specifically, it is a method of supplying a reactive gas into the plasma processing chamber 10 to react with elements contained in the etchant to generate a compound different from the etchant. When the etchant is HF gas, a chlorine-containing gas can be used as the reactive gas, for example. As the chlorine-containing gas, at least one gas selected from the group consisting of Cl2 gas, HCl gas, CHCl3 gas, CH2Cl2 gas, CH3Cl gas, CCl4 gas, BCl3 gas, SiCl4 gas, SiH2Cl2 gas, and Si2Cl6 gas can be used. By such a method, the number of etchant molecules in the plasma processing chamber 10 can be reduced, thereby reducing the partial pressure of the etchant in the plasma processing chamber 10. Furthermore, as described above, the processing gas sometimes includes a chlorine-containing gas as a halogen-containing gas. In this case, by adding a chlorine-containing gas as a reactive gas, i.e., increasing the flow rate ratio of the chlorine-containing gas, the partial pressure of the etchant in the plasma processing chamber 10 can be reduced.

[0110] The fourth method is to reduce the flow rate of the etchant supplied into the plasma processing chamber 10. When the etchant is HF gas, reducing the flow rate of HF gas supplied into the plasma processing chamber 10 can reduce the partial pressure of HF gas within the plasma processing chamber 10.

[0111] [Substrate Processing Method]

[0112] Figure 7 This is a flowchart illustrating an example of a substrate processing method according to one embodiment of the present disclosure. The control unit 2 controls each part of the main body 1 to achieve... Figure 7 Each process shown in the example.

[0113] First, control unit 2 controls a conveying device (not shown) to, for example, transport... Figure 2 The substrate W shown is moved into the plasma processing chamber 10 (S10). Then, the substrate W is placed on the substrate support portion 11, and the substrate W is held on the substrate support surface 111a by supplying voltage to the electrostatic chuck of the main body portion 111. Step S10 is an example of process a1), process b1), process c1), and process d1).

[0114] Next, the gas inside the plasma processing chamber 10 is vented through the exhaust system 40, and a processing gas containing HF gas is supplied to the plasma processing chamber 10 (S11). Then, the pressure inside the plasma processing chamber 10 is adjusted to a predetermined pressure P1. The pressure P1 can be, for example, 5 mTorr (0.65 Pa) or more and 100 mTorr (13.3 Pa) or less. Step S11 is an example of steps a2), b2), c2), and d2).

[0115] Next, etching begins (S12). Step S12 is an example of steps a3), b3), c3), and d3). In step S12, plasma is generated from the process gas within the plasma processing chamber 10 by providing a source RF signal from the RF power supply 31 to the conductive member of the substrate support 11 or the conductive member of the spray head 13. The source RF signal can be set to, for example, 2 kW or more and 10 kW or less. Furthermore, a bias RF signal is provided from the RF power supply 31 to the conductive member of the substrate support 11. As a result, a bias potential is generated on the substrate W, and the ionic components in the plasma are attracted to the substrate W, initiating etching of the substrate W. The bias RF signal can be set to, for example, 2 kW or more. The power level of the bias RF signal can be set to 10 kW or more.

[0116] Furthermore, an electrical bias voltage other than the bias RF signal can be supplied to the conductive members of the substrate support 11 instead of the bias RF signal. In one example, the electrical bias voltage is a DC voltage. The electrical bias voltage can be supplied to the conductive members of the substrate support 11 to generate a negative potential on the substrate W. The electrical bias voltage can be supplied continuously or periodically. In the case of periodically supplying the electrical bias voltage, the period of the electrical bias voltage includes two periods. The electrical bias voltage in one of the two periods is a negative polarity voltage. The voltage level (i.e., absolute value) in one of the two periods is higher than the voltage level (i.e., absolute value) in the other period. The voltage in the other period can be either negative or positive polarity. The level of the negative polarity voltage in the other period can be greater than zero or zero.

[0117] The bias voltage can be a pulse wave or a continuous wave. When the bias voltage is a pulse wave, it can be a rectangular wave pulse, a triangular wave pulse, an impulse, or a pulse of other voltage waveforms.

[0118] Furthermore, in step S12, the temperature of the substrate support portion 11 can be controlled to a low temperature. The temperature of the substrate support portion 11 can be, for example, below 20°C, below 0°C, below -10°C, below -20°C, below -30°C, below -40°C, or below -70°C. The temperature of the substrate support portion 11 can be adjusted by a heat exchange medium supplied by a cooling unit (not shown).

[0119] Next, the control unit 2 determines whether the aspect ratio of the recess 52 reaches a predetermined first aspect ratio AR1 (S13). The control unit 2 determines whether the aspect ratio of the recess 52 reaches the first aspect ratio AR1 by determining whether the etching duration is equal to the etching duration until the aspect ratio of the recess 52 reaches the first aspect ratio AR1. The etching duration until the aspect ratio of the recess 52 reaches the first aspect ratio AR1 is determined in advance through experimentation. If the aspect ratio of the recess 52 does not reach the first aspect ratio AR1 (S13: "No"), the process shown in step S13 is executed again.

[0120] On the other hand, when the aspect ratio of the recess 52 reaches the first aspect ratio AR1 (S13: "Yes"), the control unit 2 controls each part of the device body 1 to reduce the partial pressure of the etchant from pressure P1 to pressure P2, which is lower than pressure P1 (S14). Step S14 is an example of steps a4), b4), c4), and d4). The control unit 2 controls, for example, the gas supply unit 20 and the exhaust system 40 to reduce the pressure inside the plasma processing chamber 10, thereby reducing the partial pressure of the etchant. Alternatively, the partial pressure of the etchant can be reduced by adding a gas other than the etchant into the plasma processing chamber 10. Another method to reduce the partial pressure of the etchant is to supply a reactive gas that reacts with elements contained in the etchant to remove the etchant into the plasma processing chamber 10.

[0121] Therefore, for example Figure 8 As shown, the partial pressure of the etchant is maintained at pressure P1 until the aspect ratio of the recess 52 reaches the first aspect ratio AR1. Moreover, after the aspect ratio of the recess 52 reaches the first aspect ratio AR1, the partial pressure of the etchant changes to pressure P2, which is lower than pressure P1.

[0122] Next, the control unit 2 determines whether the aspect ratio of the recess 52 reaches a predetermined second aspect ratio AR2 (S15). If the aspect ratio of the recess 52 does not reach the second aspect ratio AR2 (S15: "No"), the process shown in step S15 is executed again. On the other hand, if the aspect ratio of the recess 52 reaches the second aspect ratio AR2 (S15: "Yes"), Figure 7 The illustrated substrate processing method is now complete.

[0123] The above describes one embodiment. As described above, the substrate processing method in this embodiment includes steps a1), a2), a3), and a4). In step a1), a substrate W containing a silicon-containing film 50 is provided into the plasma processing chamber 10. In step a2), a processing gas containing HF gas is supplied into the plasma processing chamber 10. In step a3), the silicon-containing film 50 is etched using plasma generated from the processing gas to form a recess 52 in the silicon-containing film 50. In step a4), control is performed so that the partial pressure of the HF gas decreases as the aspect ratio of the recess 52 increases. This improves etching productivity and suppresses shape abnormalities in the recess 52 formed by etching.

[0124] Furthermore, in the above embodiment, in step a4), the partial pressure of HF gas is reduced by lowering the pressure inside the plasma processing chamber 10. This reduces the partial pressure of the etchant.

[0125] Furthermore, in the above embodiment, in step a4), the partial pressure of HF gas can be reduced by adding dilution gas into the plasma processing chamber 10. At this time, the partial pressure of HF gas can be reduced while maintaining the pressure within the plasma processing chamber 10. In this way, the partial pressure of the etchant can also be reduced.

[0126] Furthermore, in the above embodiment, in step a4), the partial pressure of HF gas in the plasma processing chamber 10 can be reduced by supplying a reactive gas to the plasma processing chamber 10. This reactive gas is a reactive gas that reacts with elements contained in the molecules of HF gas to remove it. In this way, the partial pressure of the etchant can also be reduced.

[0127] Furthermore, in the above embodiment, in step a4), the partial pressure of the HF gas in the plasma processing chamber 10 can be reduced by decreasing the flow rate of the HF gas supplied to the plasma processing chamber 10. This also reduces the partial pressure of the etchant.

[0128] Furthermore, in the above embodiments, the reactive gas is, for example, a chlorine-containing gas. The chlorine-containing gas can be at least one gas selected from the group consisting of Cl2 gas, HCl gas, CHCl3 gas, CH2Cl2 gas, CH3Cl gas, CCl4 gas, BCl3 gas, SiCl4 gas, SiH2Cl2 gas, and Si2Cl6 gas. By adding such a gas into the plasma processing chamber 10, the partial pressure of the HF gas within the plasma processing chamber 10 can be reduced.

[0129] Furthermore, in the above embodiments, the processing gas may include a carbon-containing gas. As such a carbon-containing gas, at least one gas selected from the group consisting of CF-based gases and CHF-based gases is preferably preferred. As a CF-based gas, at least one gas selected from the group consisting of CF4, C2F2, C2F4, C3F8, C4F6, C4F8, and C5F8 can be used. As a CHF-based gas, examples include those consisting of CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, C4H2F8, C5H2F6, and C5H2F6. 10 At least one gas selected from the group consisting of gas and C5H3F7 gas. By including such a gas in the processing gas, a carbon-containing deposit is formed on the surface of mask 51, thereby suppressing the etching of mask 51. Therefore, the ratio (selectivity ratio) of the etching rate of the silicon-containing film to the etching rate of mask 51 can be improved.

[0130] Furthermore, in the above embodiments, the processing gas may include at least one gas selected from the group consisting of phosphorus-containing gases, sulfur-containing gases, and boron-containing gases. For example, phosphorus-containing gases may be selected from PF3, PF5, POF3, HPF6, PCl3, PCl5, POCl3, PBr3, PBr5, POBr3, PI3, and P4O. 10 At least one gas selected from the group consisting of P4O8, P4O6, PH3, Ca3P2, H3PO4, and Na3PO4. As a sulfur-containing gas, at least one gas selected from the group consisting of SF6, SO2, and COS can be used, for example. As a boron-containing gas, at least one gas selected from the group consisting of BCl3, BF3, BBr3, and B2H6 can be used, for example. These gases are deposited on the sidewalls of the recess 52 formed by etching to form a protective film. Therefore, bending in the recess 52 can be suppressed.

[0131] In addition, in the above embodiments, the silicon-containing film includes a silicon oxide film and at least one film selected from the group consisting of a silicon nitride film and a polycrystalline silicon film.

[0132] In addition, in the above embodiments, the silicon-containing film is a silicon oxide film, a multilayer film of silicon oxide film and silicon nitride film, or a multilayer film of silicon oxide film and polycrystalline silicon film.

[0133] Furthermore, the plasma processing apparatus in the above embodiment includes a plasma processing chamber 10, a substrate support 11, a plasma generation unit (a conductive member of the substrate support 11 or a conductive member of the spray head 13), and a control unit 2. The plasma processing chamber 10 has a gas supply port 13a and a gas outlet 10e. The substrate support 11 is disposed within the plasma processing chamber 10. A substrate W is placed on the substrate support 11. The plasma generation unit generates plasma from the processing gas supplied to the plasma processing chamber 10. The control unit 2 is configured to execute processes including steps d1), d2), d3), and d4). In step d1), the control unit 2 arranges a substrate W having a silicon-containing film 50 on the substrate support 11. In step d2), a processing gas containing HF gas is supplied to the plasma processing chamber 10 from the gas supply port 13a. In step d3), the control unit 2 generates plasma from the processing gas and uses the generated plasma to etch the silicon-containing film 50 to form a recess 52 in the silicon-containing film 50. In step d4), the control unit 2 controls the process so that the partial pressure of the HF gas decreases as the aspect ratio of the recess 52 increases. This allows for at least one of improving etching productivity and suppressing shape anomalies in the recess 52 formed by etching.

[0134] [other]

[0135] Furthermore, the technology disclosed in this application is not limited to the above-described embodiments, and various modifications can be made within the scope of its spirit.

[0136] For example, in the above embodiment, the partial pressure of the etchant is changed once during the formation of the recess 52, but the disclosed technology is not limited to this. Other methods may also be as follows: Figure 9 As shown, the partial pressure of the etchant is changed multiple times during the formation of the recess 52.

[0137] Figure 9 This is a flowchart illustrating other examples of substrate processing methods. The control unit 2 controls each part of the main body 1 to achieve... Figure 9 Each process shown in the example.

[0138] First, control unit 2 controls a conveying device (not shown) to transport, for example, a... Figure 2 The substrate W shown is placed into the plasma processing chamber 10 (S20). Then, the gas inside the plasma processing chamber 10 is vented through the exhaust system 40, and a processing gas containing HF gas is supplied into the plasma processing chamber 10 (S21). Then, etching begins (S22). The processing in steps S20 to S22 is similar to... Figure 7 The steps S10 to S12 illustrated are processed in the same way.

[0139] Next, the control unit 2 determines whether the aspect ratio of the recess 52 has increased by a predetermined first amount. The control unit 2 determines, for example, whether the etching duration has reached the etching duration until the aspect ratio of the recess 52 increases by the first amount. The etching duration until the aspect ratio of the recess 52 increases by the first amount is determined in advance through experimentation. If the aspect ratio of the recess 52 has not increased by the first amount (S23: "No"), the process shown in step S23 is executed again.

[0140] On the other hand, when the aspect ratio of the recess 52 increases by a first amount (S23: "Yes"), the control unit 2 controls each part of the main body 1 of the device to reduce the partial pressure of the etchant from pressure P1 to pressure P2, which is lower than pressure P1 (S24). Pressure P1 is an example of the first pressure, and pressure P2 is an example of the second pressure. The processing in step S24 is similar to... Figure 7 The process of step S14 shown is the same.

[0141] Next, the control unit 2 determines whether the aspect ratio of the recess 52 has increased by a predetermined second amount (S25). The control unit 2 determines, for example, whether the etching duration has reached the etching duration until the aspect ratio of the recess 52 increases by the second amount. The etching duration until the aspect ratio of the recess 52 increases by the second amount is determined in advance through experimentation. If the aspect ratio of the recess 52 has not increased by the second amount (S25: "No"), the process shown in step S25 is executed again.

[0142] On the other hand, if the aspect ratio of the recess 52 increases by a second amount (S25: "Yes"), the control unit 2 determines whether the aspect ratio of the recess 52 has reached a predetermined third aspect ratio (S26). If the aspect ratio of the recess 52 has not reached the third aspect ratio (S26: "No"), the control unit 2 controls each part of the device body 1 to increase the partial pressure of the etchant from pressure P2 to pressure P1 (S27). Then, the process shown in step S23 is executed again. On the other hand, if the aspect ratio of the recess 52 reaches the third aspect ratio (S26: "Yes"), Figure 9 The illustrated substrate processing method is now complete.

[0143] Thus, during the period of etching of the recess 52, for example, Figure 10The etching agent is controlled as shown, so that the partial pressure of the etchant alternates between pressure P1 and pressure P2. Here, when the partial pressure of the etchant is controlled at pressure P1, etching is performed at a high etching rate to form the recess 52. Furthermore, when the partial pressure of the etchant is controlled at pressure P2, which is lower than pressure P1, the cross-section of the bottom of the recess 52 is formed into a rectangular shape. In this way, by controlling the partial pressure to alternately repeat as pressure P1 or pressure P2, the rapid progress of etching and the shaping of the bottom of the recess 52 are performed alternately. Therefore, it is possible to simultaneously improve etching productivity and suppress abnormal shapes of the recess 52 formed by etching.

[0144] Furthermore, in a process where the partial pressure of the etchant is alternately repeated as pressure P1 and pressure P2, for example, it can be done as follows: Figure 11 The pressure P1 on the higher side is controlled as shown, so that it gradually decreases as the depth-to-width ratio of the recess 52 increases. Figure 11 In the example, the pressure P1 is controlled so that it gradually decreases as the aspect ratio of the recess 52 increases, such as pressure P11, pressure P12, pressure P13, ... . This prevents the reaction byproduct 53 from becoming less volatile as the aspect ratio increases. Furthermore, the lower pressure P2 can be kept constant regardless of the increase in the aspect ratio of the recess 52.

[0145] Furthermore, the partial pressure of the etchant can be controlled based on the output value of the flow controller 22. Alternatively, the partial pressure of the etchant can be controlled based on an estimate obtained by monitoring the luminescence state of the plasma. For example, the luminescence state of the plasma can be measured using an optical sensor 114, such as an optical emission spectroscopy (OES) sensor, installed in the plasma processing chamber 10. Therefore, the partial pressure of the etchant can be measured even within the plasma, including the etchant that has dissociated or formed in the plasma, thus enabling precise control of the etchant's partial pressure.

[0146] Furthermore, in the above embodiment, HF gas is used as the etchant, but the disclosed technology is not limited to this. Alternatively, a gas capable of generating HF seeds within the plasma processing chamber 10 during plasma processing can be used. HF seeds include at least one of hydrogen fluoride gas, free radicals, and ions. In one example, the gas capable of generating HF seeds can be a hydrofluorocarbon gas. Alternatively, the gas capable of generating HF seeds can be a mixture containing a hydrogen source and a fluorine source. The hydrogen source can be, for example, H2, NH3, H2O, H2O2, or hydrocarbons. The fluorine source can be NF3, SF6, WF6, XeF2, fluorocarbons, or hydrofluorocarbons. When using a gas capable of generating HF seeds, control is performed so that the partial pressure of the HF seeds decreases as the aspect ratio of the recess 52 increases. For example, the partial pressure of the HF seeds can be calculated based on the luminescence state of the plasma measured by the OES as described above. Thus, it is possible to simultaneously improve etching productivity and suppress shape anomalies in the recess 52 formed by etching.

[0147] Alternatively, reactive species contained in the plasma generated from the process gas can be used as an etchant. As such a process gas, a process gas containing an etchant is used, wherein the etchant is at least one gas selected from the group consisting of gases containing fluorine atoms, gases containing carbon and fluorine, and gases containing carbon, hydrogen, and fluorine atoms. In the fluorine-containing gas, F radicals contained in the plasma generated from the fluorine-containing gas act as the etchant. In the carbon and fluorine-containing gas, CF radicals contained in the plasma generated from the carbon and fluorine-containing gas act as the etchant. In the carbon, hydrogen, and fluorine-containing gas, CF radicals contained in the plasma generated from the carbon, hydrogen, and fluorine-containing gas act as the etchant. Furthermore, control is performed so that the partial pressure of the etchant decreases with increasing aspect ratio. This allows for simultaneous improvement in etching productivity and suppression of shape anomalies in the recesses 52 formed by etching. Furthermore, when reducing the partial pressure of the etchant by adding a reactive gas, adding a reactive gas such as a hydrogen-containing gas or an oxygen-containing gas is considered.

[0148] Furthermore, in the above-described embodiment, control is performed to reduce the partial pressure of the HF gas (etchant) as the aspect ratio of the recess 52 formed by etching increases, but the disclosed technology is not limited to this. Alternatively, the partial pressure of the etchant can be adjusted to any value corresponding to the increase in the aspect ratio of the recess 52. That is, control can be performed to reduce the partial pressure of the etchant corresponding to the increase in the aspect ratio of the recess 52, or control can be performed to increase the partial pressure of the etchant. The effect of controlling the partial pressure of the HF gas (etchant) to decrease as the aspect ratio of the recess 52 increases is as described above. On the other hand, when the partial pressure of the HF gas (etchant) is controlled to increase as the aspect ratio of the recess 52 increases, etching can be performed after the shape of the recess is formed. Therefore, the etching rate can be increased while maintaining the shape of the recess.

[0149] Furthermore, in the above embodiments, as an example of a plasma source, a plasma processing apparatus 100 using capacitively coupled plasma (CCP) was described, but the plasma source is not limited to this. Examples of plasma sources other than capacitively coupled plasma include inductively coupled plasma (ICP), microwave-excited surface wave plasma (SWP), electron cyclotron resonance plasma (ECP), and helical wave-excited plasma (HWP).

[0150] Furthermore, it should be considered that the embodiments disclosed herein are illustrative in all respects and not restrictive. In fact, the above-described embodiments can be implemented in various ways. In addition, the above-described embodiments can be omitted, substituted, or modified in various ways without departing from the appended claims and their spirit.

[0151] Explanation of reference numerals in the attached figures

[0152] W: Substrate; 100: Plasma processing device; 1: Device body; 2: Control unit; 2a: Computer; 10: Plasma processing chamber; 10e: Gas exhaust port; 10s: Plasma processing space; 11: Substrate support; 111: Main body; 111a: Substrate support surface; 111b: Annular support surface; 112: Annular assembly; 113: Quartz window; 114: Optical sensor; 13a: Gas supply port; 20: Gas supply unit; 30: Power supply; 31: RF power supply; 32: DC power supply; 40: Exhaust system; 50: Silicon film; 51: Mask; 51a: Opening; 52: Recess; 53: Reaction byproduct.

Claims

1. A substrate processing method, comprising the following steps: Step a1) involves providing a substrate containing a silicon film into the cavity; Step a2), supplying a processing gas containing HF gas into the chamber; Step a3), etching the silicon-containing film using plasma generated from the processing gas to form recesses in the silicon-containing film; and In step a4), control is performed so that the partial pressure of the HF gas decreases as the depth-to-width ratio of the recess increases.

2. The substrate processing method according to claim 1, characterized in that, In step a4), the partial pressure of the HF gas is reduced by lowering the pressure inside the chamber.

3. The substrate processing method according to claim 1, characterized in that, In step a4), the partial pressure of the HF gas is reduced by adding dilution gas into the chamber.

4. The substrate processing method according to claim 1, characterized in that, In step a4), the partial pressure of the HF gas in the chamber is reduced by supplying a reactive gas to the chamber. The reactive gas is a reactive gas that reacts with elements contained in the molecules of the HF gas to remove the molecules of the HF gas.

5. The substrate processing method according to claim 4, characterized in that, The reactive gas is a chlorine-containing gas.

6. The substrate processing method according to claim 5, characterized in that, The chlorine-containing gas is at least one gas selected from the group consisting of Cl2 gas, HCl gas, CHCl3 gas, CH2Cl2 gas, CH3Cl gas, CCl4 gas, BCl3 gas, SiCl4 gas, SiH2Cl2 gas, and Si2Cl6 gas.

7. The substrate processing method according to claim 1, characterized in that, In step a4), the partial pressure of the HF gas in the chamber is reduced by decreasing the flow rate of the HF gas supplied to the chamber.

8. The substrate processing method according to any one of claims 1 to 7, characterized in that, In step a3), the partial pressure of the HF gas is controlled to a first partial pressure. In step a4), the partial pressure of the HF gas is controlled to a second partial pressure that is lower than the first partial pressure. Alternately repeat steps a3) and a4).

9. The substrate processing method according to claim 8, characterized in that, In step a3), which is repeated alternately with step a4), control is performed so that the first partial pressure gradually decreases as the depth-to-width ratio of the recess increases.

10. The substrate processing method according to any one of claims 1 to 7, characterized in that, The processed gas includes carbon-containing gases.

11. The substrate processing method according to claim 10, characterized in that, The carbon-containing gas is at least one gas selected from the group consisting of fluorocarbon gases and hydrofluorocarbon gases.

12. The substrate processing method according to claim 11, characterized in that, The fluorinated hydrocarbon gas is at least one gas selected from the group consisting of CF4 gas, C2F2 gas, C2F4 gas, C3F8 gas, C4F6 gas, C4F8 gas and C5F8 gas.

13. The substrate processing method according to claim 11, characterized in that, The hydrofluorocarbon gas is derived from CHF3, CH2F2, CH3F, C2HF5, C2H2F4, C2H3F3, C2H4F2, C3HF7, C3H2F2, C3H2F6, C3H2F4, C3H3F5, C4H5F5, C4H2F6, C4H2F8, C5H2F6, and C5H2F... 10 At least one gas selected from the group consisting of gas and C5H3F7 gas.

14. The substrate processing method according to any one of claims 1 to 7, characterized in that, The processing gas comprises at least one gas selected from the group consisting of phosphorus-containing gases, sulfur-containing gases, and boron-containing gases.

15. The substrate processing method according to claim 14, characterized in that, The phosphorus-containing gas is derived from PF3, PF5, POF3, HPF6, PCl3, PCl5, POCl3, PBr3, PBr5, POBr3, PI3, and P4O. 10 At least one gas selected from the group consisting of gas, P4O8 gas, P4O6 gas, PH3 gas, Ca3P2 gas, H3PO4 gas, and Na3PO4 gas.

16. The substrate processing method according to claim 14, characterized in that, The sulfur-containing gas is at least one gas selected from the group consisting of SF6 gas, SO2 gas and COS gas.

17. The substrate processing method according to claim 14, characterized in that, The boron-containing gas is at least one gas selected from the group consisting of BCl3 gas, BF3 gas, BBr3 gas and B2H6 gas.

18. The substrate processing method according to any one of claims 1 to 7, characterized in that, The silicon-containing film includes a silicon oxide film and at least one film selected from the group consisting of a silicon nitride film and a polycrystalline silicon film.

19. The substrate processing method according to any one of claims 1 to 7, characterized in that, The silicon-containing film is a silicon oxide film, a multilayer film of silicon oxide and silicon nitride, or a multilayer film of silicon oxide and polycrystalline silicon.

20. The substrate processing method according to any one of claims 1 to 7, characterized in that, In step a4), the partial pressure of the HF gas is estimated by monitoring the luminescence state of the plasma, and control is performed to reduce the estimated partial pressure of the HF gas.

21. A substrate processing method, comprising the following steps: Step b1) involves providing a substrate containing a silicon film into the cavity; Step b2) involves supplying a processing gas containing a gas capable of generating HF into the chamber. Step b3) involves etching the silicon-containing film using plasma generated from the processing gas to form recesses in the silicon-containing film; and Step b4) is controlled to reduce the partial pressure of the HF type as the depth-to-width ratio of the recess increases.

22. A substrate processing method, comprising the following steps: Step c1) involves providing a substrate containing a silicon film into the cavity; Step c2) Supplying a processing gas containing an etchant into the chamber, the etchant being at least one gas selected from the group consisting of a gas containing fluorine atoms, a gas containing carbon and fluorine, and a gas containing carbon, hydrogen, and fluorine atoms. Step c3) involves etching the silicon-containing film using plasma generated from the processing gas to form recesses in the silicon-containing film; and Step c4) involves changing the partial pressure of the etchant as the depth-to-width ratio of the recess increases.

23. A substrate processing apparatus comprising: A chamber having a gas supply port and a gas exhaust port; A substrate support portion is disposed within the cavity; A plasma generation unit that generates plasma from the processing gas supplied to the chamber; as well as Control Department in, The control unit is configured to execute a process including the following steps: Step d1) involves placing a substrate containing a silicon film on the substrate support portion; Step d2), supplying a processing gas containing HF gas into the chamber; Step d3), generating plasma from the processing gas, and using the generated plasma to etch the silicon-containing film to form a recess in the silicon-containing film; and In step d4), control is performed so that the partial pressure of the HF gas decreases as the depth-to-width ratio of the recess increases.

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