Etching method and plasma processing apparatus

Abstract

A technique for improving mask selection ratio in etching is provided. The etching method according to the present disclosure includes: a step (a) of preparing a substrate including a silicon-containing film and a mask on the silicon-containing film, the mask including an opening pattern; (b) a step for forming a metal-containing film on the mask; and (c) etching the silicon-containing film by generating plasma from a first processing gas containing a hydrogen fluoride gas.

Description

Technical Field

[0001] Exemplary embodiments of the present disclosure relate to an etching method and a plasma processing apparatus. Background Art

[0002] Patent Document 1 discloses a method of etching a multilayer film.

[0003] Prior art literature

[0004] Patent Literature

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

[0006] Problem that the invention aims to solve

[0007] The present disclosure provides a technique for improving mask selectivity in etching.

[0008] Solutions for solving problems

[0009] In an exemplary embodiment of the present disclosure, an etching method is provided, which includes: step (a), preparing a substrate including a silicon-containing film and a mask on the silicon-containing film, the mask including an opening pattern; step (b), forming a metal-containing film on the mask; and step (c), generating plasma from a first processing gas including hydrogen fluoride gas to etch the silicon-containing film.

[0010] Effects of the Invention

[0011] According to an exemplary embodiment of the present disclosure, a technique for improving a mask selectivity ratio in etching can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a diagram for explaining a configuration example of a plasma processing system.

[0013] Figure 2 It is a diagram for explaining a configuration example of a capacitive coupling type plasma processing apparatus.

[0014] Figure 3 This is a diagram for explaining an example of the selectivity and the bowing.

[0015] Figure 4 This is a flowchart showing an example of this method.

[0016] Figure 5 2 is a diagram showing an example of a cross-sectional structure of the substrate W prepared in step ST1 .

[0017] Figure 6 1 is a diagram showing an example of a cross-sectional structure of the substrate W after being processed in step ST2 .

[0018] Figure 7 1 is a diagram showing an example of a cross-sectional structure of the substrate W after being processed in step ST3 .

[0019] Figure 8 This is a diagram showing an example of a cooler.

[0020] Fig. 9 This is a table showing the experimental conditions and experimental results of Experiment 1.

[0021] Fig.10 This is a table showing the experimental conditions and experimental results of Experiment 2.

[0022] Fig.11 3 is a graph showing the experimental results of Experiment 3. DETAILED DESCRIPTION

[0023] Hereinafter, each embodiment of the present disclosure will be described.

[0024] In an exemplary embodiment, an etching method is provided, comprising: step (a) of preparing a substrate including a silicon-containing film and a mask on the silicon-containing film, the mask including an opening pattern; step (b) of forming a metal-containing film on the mask; and step (c) of generating plasma from a first process gas including hydrogen fluoride gas to etch the silicon-containing film.

[0025] In an exemplary embodiment, the silicon-containing film includes a silicon oxide film, a silicon nitride film, a polysilicon film, or a stacked film including two or more thereof.

[0026] In an exemplary embodiment, the mask includes a silicon-containing film different from the silicon-containing film, or a carbon-containing film or a metal-containing film.

[0027] In an exemplary embodiment, the mask includes an amorphous carbon film or a spin-on carbon film.

[0028] In an exemplary embodiment, the mask includes a film including at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium, or an oxide film, a nitride film, or a carbide film including at least one metal.

[0029] In an exemplary embodiment, (b) includes forming the metal-containing film from a second process gas including a metal-containing gas.

[0030] In an exemplary embodiment, the metal-containing gas includes at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.

[0031] In an exemplary embodiment, the metal-containing gas includes tungsten hexafluoride or molybdenum hexafluoride.

[0032] In an exemplary embodiment, (b) includes generating a plasma from the second process gas to form the metal-containing film.

[0033] In an exemplary embodiment, (b) includes adsorbing a metal-containing precursor to a mask to form a metal-containing film.

[0034] In an exemplary embodiment, (b) includes generating plasma from a gas that oxidizes or reduces at least a portion of the metal-containing precursor adsorbed on the mask to form the metal-containing film.

[0035] In an exemplary embodiment, in (b), a portion of the metal-containing precursor adsorbed to the mask is not oxidized or reduced.

[0036] In an exemplary embodiment, (b) includes forming the metal-containing film by physical evaporation.

[0037] In an exemplary embodiment, (a) includes disposing a substrate on a substrate support portion, and (b) includes forming a metal-containing film by sputtering a metal-containing electrode disposed opposite to the substrate support portion.

[0038] In an exemplary embodiment, regarding the etching method, the first process gas further includes a phosphorus-containing gas.

[0039] In an exemplary embodiment, the phosphorus-containing gas includes phosphorus halide or phosphorus chloride.

[0040] In an exemplary embodiment, the first process gas includes a carbon-containing gas.

[0041] In an exemplary embodiment, the first process gas further includes a halogen-containing gas.

[0042] In an exemplary embodiment, the first process gas includes at least one gas selected from the group consisting of an oxygen-containing gas, a boron-containing gas, and a metal-containing gas.

[0043] In an exemplary embodiment, the flow rate of the hydrogen fluoride gas is the largest among the first process gases.

[0044] In an exemplary embodiment, in (b), the temperature of a substrate support portion that supports the substrate is set to a first temperature, and in (c), the temperature of the substrate support portion is set to a second temperature that is lower than the first temperature.

[0045] In an exemplary embodiment, the first temperature is above 0°C, and the second temperature is below 0°C.

[0046] In an exemplary embodiment, in the etching method, a cycle including (b) and (c) is repeated a plurality of times.

[0047] In an exemplary embodiment, an etching method is provided, comprising: step (a) of preparing a substrate including a silicon-containing film and a mask on the silicon-containing film, the mask including an opening pattern; step (b) of forming a metal-containing film on the mask; and step (c) of generating plasma from a first process gas to etch the silicon-containing film.

[0048] In one exemplary embodiment, the first process gas includes one or more gases that generate a plasma including a hydrogen fluoride species when the plasma is generated from the first process gas.

[0049] In an exemplary embodiment, a plasma processing apparatus is provided, the plasma processing apparatus comprising a chamber and a control unit. In the plasma processing apparatus, the control unit is configured to perform the following control: control (a) to prepare a substrate including a silicon-containing film and a mask on the silicon-containing film in the chamber, the mask including an opening pattern; control (b) to form a metal-containing film on the mask; and control (c) to generate plasma from a first processing gas including hydrogen fluoride gas to etch the silicon-containing film.

[0050] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, in each of the drawings, the same reference numerals are given to the same or identical elements, and repeated descriptions are omitted. Unless otherwise specified, the positional relationships such as up, down, left, and right are described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

[0051] <Configuration Example of Plasma Processing System>

[0052] Figure 1 : is a diagram for illustrating a structural example of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing device 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing device 1 is an example of a substrate processing device. The plasma processing device 1 includes a plasma processing chamber 10, a substrate support portion 11, and a plasma generating portion 12. The plasma processing chamber 10 has a plasma processing space. In addition, the plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to the gas supply portion 20 described later, and the gas exhaust port is connected to the exhaust system 40 described later. The substrate support portion 11 is arranged in the plasma processing space and has a substrate supporting surface for supporting a substrate.

[0053] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be a capacitively coupled plasma (CCP: Capacitively Coupled Plasma), an inductively coupled plasma (ICP: Inductively Coupled Plasma), an ECR plasma (Electron-Cyclotron-resonance plasma: Electron Cyclotron Resonance), a helicon wave excited plasma (HWP: Helicon Wave Plasma), or a surface wave plasma (SWP: Surface Wave Plasma), etc. In addition, various types of plasma generating units including an AC (Alternating Current: Alternating Current) plasma generating unit and a DC (Direct Current: Direct Current) plasma generating unit may also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generating unit has a frequency in the range of 100kHz to 10GHz. Therefore, the AC signal includes an RF (Radio Frequency: Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100kHz to 150MHz.

[0054] The control unit 2 processes computer executable commands that cause the plasma processing device 1 to perform various processes described in the present disclosure. The control unit 2 can be configured to control the various elements of the plasma processing device 1 to perform the various processes described herein. In one embodiment, a part or all of the control unit 2 may also be included in the plasma processing device 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 can be configured to perform various control actions by reading a program from the storage unit 2a2 and executing the read program. The program can be stored in the storage unit 2a2 in advance, or it can be obtained via a medium when necessary. The obtained program is stored in the storage unit 2a2, and is read and executed from the storage unit 2a2 by the processing unit 2a1. The medium can be various storage media that can be read by the computer 2a, or it can be a communication line connected to the communication interface 2a3. The processing unit 2a1 can be a CPU (Central Processing Unit). The storage unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0055] <Configuration Example of Capacitively Coupled Plasma Processing Apparatus>

[0056] Next, a configuration example of a capacitive coupling type plasma processing apparatus will be described as an example of the plasma processing apparatus 1 . Figure 2 It is a diagram for explaining a configuration example of a capacitive coupling type plasma processing apparatus.

[0057] A capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. In addition, the plasma processing apparatus 1 includes a substrate support unit 11 and a gas inlet unit. The gas inlet unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet unit includes a shower head 13. The substrate support unit 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, the side wall 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support unit 11 are electrically insulated from the shell of the plasma processing chamber 10.

[0058] The substrate support portion 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central area 111a for supporting a substrate W, and an annular area 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular area 111b of the main body 111 surrounds the central area 111a of the main body 111 when viewed from above. The substrate W is arranged on the central area 111a of the main body 111, and the ring assembly 112 is arranged on the annular area 111b of the main body 111 in a manner that surrounds the substrate W on the central area 111a of the main body 111. Therefore, the central area 111a is also referred to as a substrate supporting surface for supporting the substrate W, and the annular area 111b is also referred to as a ring supporting surface for supporting the ring assembly 112.

[0059] In one embodiment, the main body 111 includes a base 1110 and an electrostatic holding disk 1111. The base 1110 includes a conductive component. The conductive component of the base 1110 can function as a lower electrode. The electrostatic holding disk 1111 is arranged on the base 1110. The electrostatic holding disk 1111 includes a ceramic component 1111a and an electrostatic electrode 1111b arranged in the ceramic component 1111a. The ceramic component 1111a has a central area 111a. In one embodiment, the ceramic component 1111a also has an annular area 111b. In addition, other components surrounding the electrostatic holding disk 1111, such as an annular electrostatic holding disk and an annular insulating component, may also have an annular area 111b. In this case, the ring assembly 112 may be arranged on the annular electrostatic holding disk or the annular insulating component, or may be arranged on both the electrostatic holding disk 1111 and the annular insulating component. In addition, at least one RF / DC electrode combined with the RF power supply 31 and / or DC power supply 32 described later may also be arranged in the ceramic component 1111a. In this case, at least one RF / DC electrode functions as a lower electrode. When the bias RF signal and / or DC signal described later is supplied to at least one RF / DC electrode, the RF / DC electrode is also referred to as a bias electrode. In addition, the conductive component of the base 1110 and at least one RF / DC electrode may also function as multiple lower electrodes. In addition, the electrostatic electrode 1111b may also function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0060] The ring assembly 112 includes one or more ring-shaped members. In one embodiment, the one or more ring-shaped members include one or more edge rings and at least one cover ring. The edge ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0061] In addition, the substrate support 11 may also include a temperature control module, which is configured to adjust at least one of the electrostatic holding disk 1111, the ring assembly 112 and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or gas flows in the flow path 1110a. In one embodiment, a flow path 1110a is formed in the base 1110, and one or more heaters are arranged in the ceramic component 1111a of the electrostatic holding disk 1111. In addition, the substrate support 11 may also include a heat transfer gas supply unit, which is configured to supply a heat transfer gas to the gap between the back side of the substrate W and the central area 111a.

[0062] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas introduction ports 13c. The processing gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s from the plurality of gas introduction ports 13c through the gas diffusion chamber 13b. In addition, the shower head 13 includes at least one upper electrode. In addition, the gas introduction unit may also include one or more side gas injection units (SGI: Side Gas Injector) in addition to the shower head 13, and the one or more side gas injection units are installed in one or more openings formed in the side wall 10a.

[0063] 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 processing gas from the respective corresponding gas sources 21 to the shower head 13 via the respective corresponding flow controllers 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. In addition, the gas supply unit 20 may also include at least one flow modulation device, which modulates or pulses the flow of at least one processing gas.

[0064] The power supply 30 includes an RF 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 RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. Thus, plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of the plasma generating unit 12. In addition, a bias potential can be generated on the substrate W by supplying a bias RF signal to at least one lower electrode, and ion components in the formed plasma can be attracted to the substrate W.

[0065] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit, and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may also be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0066] The second RF generating unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit, and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100kHz to 60MHz. In one embodiment, the second RF generating unit 31b may also be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In addition, in various embodiments, at least one of the source RF signal and the bias RF signal may also be pulsed.

[0067] In addition, the power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generating unit 32a and a second DC generating unit 32b. In one embodiment, the first DC generating unit 32a is connected to at least one lower electrode and is configured to generate a first DC signal. The generated first DC signal is applied to at least one lower electrode. In one embodiment, the second DC generating unit 32b is connected to at least one upper electrode and is configured to generate a second DC signal. The generated second DC signal is applied to at least one upper electrode.

[0068] In various embodiments, the first and second DC signals may also be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulse may have a rectangular, trapezoidal, triangular or a combination thereof pulse waveform. In one embodiment, a waveform generator for generating a sequence of voltage pulses according to a DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. In the case where the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulse may have a positive polarity or a negative polarity. In addition, the sequence of voltage pulses may also include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses in one cycle. In addition, the first and second DC generators 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generator 32a may be provided to replace the second RF generator 31b.

[0069] The exhaust system 40 can be connected to, for example, a gas exhaust port 10e disposed at the bottom of the plasma processing chamber 10. The exhaust system 40 can include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump can include a turbomolecular pump, a dry pump, or a combination thereof.

[0070] <An Example of State of Substrate Before and After Plasma Etching>

[0071] One of the indicators for evaluating plasma etching is the selectivity between the mask and the etching target film. For example, the selectivity can be expressed by the ratio of the etching rate of the etching target film to the etching rate of the mask when the etching target film is etched through the mask.

[0072] In addition, as one of the shape abnormalities in plasma etching, bowing is known. Bowing is a phenomenon in which the opening size of a part of the side wall of the recess formed by etching becomes larger than the opening size of the top of the recess. The part where the bowing occurs has, for example, a barrel-shaped shape when observed in cross section. It is believed that the bowing may be caused by a part of the side wall of the recess being cut off by ions rebounding from a mask or the like.

[0073] Figure 3 is a diagram for explaining an example of selectivity and bow bending. Figure 3 Among them, (A) is a diagram showing an example of a cross-sectional structure of a substrate in a state where a mask MK including an opening OP is formed on an etching target film EF. (B) is a diagram showing an example of a cross-sectional structure of a substrate in a state where the etching target film EF is etched through the opening OP of the mask MK under a certain condition. (C) is a diagram showing an example of a cross-sectional structure of a substrate in a state where the etching target film EF is etched through the opening OP of the mask MK under other conditions.

[0074] exist Figure 3 In (B), the selectivity can be expressed by Db / Da, that is, the etching amount (or etching rate) of the etching target film EF relative to the etching amount (or etching rate) of the mask MK. Figure 3 In (C), the selectivity can be expressed by Db / Dc, that is, the etching amount (or etching rate) of the etching target film EF relative to the etching amount (or etching rate) of the mask MK. Figure 3 The selection ratio in (B) Figure 3 The selectivity in (C) is high. The selectivity may vary depending on the material of the mask MK, the material of the etching target film EF, etching conditions, and the like.

[0075] exist Figure 3In the example (C), a barrel-shaped bow Bow is generated on the upper side of the concave portion RC (low aspect ratio region) when viewed from the cross section. The opening size of the portion of the concave portion RC where the bow Bow is generated is larger than the opening size of the middle to lower side of the concave portion RC (medium aspect ratio region to high aspect ratio region). In addition, the bow is generated not only on the upper side of the concave portion RC, but sometimes also on the middle to lower side of the concave portion RC.

[0076] An etching method according to an exemplary embodiment of the present disclosure (hereinafter also referred to as "this method") can improve the selectivity in etching. In addition, this method can suppress bowing in etching. The following is described with reference to the accompanying drawings.

[0077] <An example of this method>

[0078] Figure 4 1 is a flowchart showing an example of the present method. The present method includes a step ST1 of preparing a substrate, a step ST2 of forming a metal-containing film on a mask, and a step ST3 of etching an etching target film. In one embodiment, the processing in each step can be performed by a plasma processing device 1 (see Figure 1 , Figure 2 In the following example, the control unit 2 controls the capacitively coupled plasma processing device 1 (refer to Figure 2 ) to execute this method.

[0079] (Step ST1: Preparation of substrate)

[0080] A substrate is prepared in step ST1 . In step ST1 , a substrate W is placed in the central region 111 a of the substrate support 11 and is held on the substrate support 11 by the electrostatic holding disk 1111 . Figure 5 1 is a diagram showing an example of a cross-sectional structure of a substrate W prepared in step ST1. Figure 5 As shown, the substrate W includes an etching target film EF and a mask MK disposed on the etching target film EF. In one embodiment, the etching target film EF may also be formed on the base film UF. The substrate W may be used for manufacturing semiconductor devices. The semiconductor devices include, for example, semiconductor memory devices such as DRAM and 3D-NAND flash memory.

[0081] In one embodiment, the base film UF is a silicon wafer, an organic film formed on a silicon wafer, a dielectric film, a metal film, a semiconductor film, etc. In one embodiment, the base film UF may also include an etching stop film. In one embodiment, the etching stop film includes at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, indium, gallium and zinc. The etching stop film may, for example, include carbides or silicides of the above metals. The etching stop film may, for example, be a tungsten-containing film. The etching stop film may also further include tungsten and at least one selected from the group consisting of silicon, carbon and nitrogen. In one example, the etching stop film includes at least one selected from the group consisting of tungsten carbide, tungsten silicide, WSiN and WSiC. The etching stop film may, for example, include at least one selected from the group consisting of ruthenium, tungsten silicide, titanium nitride, molybdenum and InGaZnO.

[0082] In one embodiment, the base film UF may be formed by stacking a plurality of films. When the base film UF is formed by a plurality of films, the etching stopper film may be formed on the uppermost layer of the base film UF. That is, the etching stopper film may be arranged to be in contact with the etching target film EF.

[0083] The etching target film EF is a film to be etched by this method. The etching target film EF may be composed of a single film or may be composed of a plurality of films stacked on top of each other.

[0084] In one embodiment, the etching object film EF is a silicon-containing film. The silicon-containing film can be a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a silicon carbonitride film, a polysilicon film, or a carbon-containing silicon film. The silicon-containing film can also be composed of a plurality of films stacked together. For example, the silicon-containing film can be composed of a silicon oxide film and a silicon nitride film stacked alternately. For example, the silicon-containing film can also be composed of a silicon oxide film and a polysilicon film stacked alternately. For example, the silicon-containing film can also be a stacked film including a silicon nitride film, a silicon oxide film, and a polysilicon film. For example, the silicon-containing film can also be composed of a silicon oxide film and a silicon carbonitride film stacked together. For example, the silicon-containing film can also be a stacked film including a silicon oxide film, a silicon nitride film, and a silicon carbonitride film. The silicon-containing film can be a silicon-containing film doped with phosphorus, boron, nitrogen, etc.

[0085] The mask MK has a pattern that is transferred to the etching target film EF by etching. The mask MK may be a single-layer mask consisting of one layer, or a multi-layer mask consisting of two or more layers. Figure 5 As shown, the side wall SS of the mask MK defines at least one opening OP on the etching target film EF. The opening OP is a space on the etching target film EF and is surrounded by the side wall SS of the mask MK. That is, the upper surface of the etching target film EF has an area covered by the mask MK and an area exposed at the bottom of the opening OP.

[0086] The opening OP can be viewed from above the substrate W, that is, Figure 5 The mask MK has an arbitrary shape when observing the substrate W from the top to the bottom. The shape may be, for example, a circle, an ellipse, a rectangle, a line, or a shape obtained by combining one or more of them. The mask MK may also have a plurality of side walls, and the plurality of side walls define a plurality of openings OP. The plurality of openings OP may respectively have a line shape, and be arranged at certain intervals to form a pattern of line width and line spacing. In addition, the plurality of openings OP may respectively have a hole shape to form an array pattern. In one example, the aspect ratio of the mask MK (the ratio of the depth to the width of the opening OP) may be greater than 20, may be greater than 30, or may be greater than 40.

[0087] The mask MK can be appropriately selected according to the etching target film EF. In one embodiment, the mask MK is formed of a material whose etching rate with respect to the plasma formed in the steps ST2 and ST3 is lower than the etching rate of the etching target film EF.

[0088] In one embodiment, the mask MK is a carbon-containing mask, a silicon-containing mask or a metal-containing mask. In one example, the carbon-containing mask is an amorphous carbon (ACL) film, a spin-on carbon (SOC) film or a photoresist film. The ACL film may also be doped with elements such as boron, arsenic, tungsten, and xenon.

[0089] When the mask MK is a silicon-containing mask and the etching target film EF is a silicon-containing film, the mask MK may be a silicon-containing film different from the etching target film EF. For example, when the etching target film EF is a stacked film of a silicon oxide film and a silicon nitride film, the mask MK may be a polysilicon film.

[0090] The metal-containing mask can be a metal-containing film containing tungsten (W), molybdenum (Mo), titanium (Ti), or the like.

[0091] The base film UF, the etching object film EF and the mask MK can be formed by any method. For example, the base film UF, the etching object film EF and the mask MK can be formed by a CVD method, an ALD method, a PVD method, a spin coating method, etc. The mask MK can also be formed by photolithography, for example. In addition, the opening OP of the mask MK can be formed by etching the mask MK. The base film UF, the etching object film EF and the mask MK can be flat films, respectively, or films with projections and depressions. In addition, the substrate W can also have other films under the base film UF. In this case, a recessed portion having a shape corresponding to the opening OP can also be formed in the etching object film EF and the base film UF, and used as a mask for etching the other film.

[0092] At least a part of the process of forming the base film UF, the etching target film EF and the mask MK of the substrate W can be performed in the plasma processing space 10s as a part of the step ST11. For example, in the case of forming the opening OP of the mask MK by etching, the etching of the step ST11 and the etching of the step ST2 can be performed continuously in the plasma processing space 10s. In one embodiment, the substrate W can be provided to the plasma processing space 10s after all or part of the substrate W is formed in a device or chamber outside the plasma processing device 1.

[0093] In one embodiment, after the substrate W is provided to the central area 111a of the substrate support 11, the substrate support 11 is controlled to a given temperature by the temperature control module. In one example, controlling the temperature of the substrate support 11 to a given temperature includes making the temperature of the heat transfer fluid flowing in the flow path 1110a or the heater temperature a given temperature, or a temperature different from the given temperature. In addition, the timing when the heat transfer fluid starts to flow in the flow path 1110a may be before the substrate W is placed on the substrate support 11, or after the substrate W is placed on the substrate support 11, or at the same time. In addition, the temperature of the substrate support 11 may be controlled to a given temperature before step ST1.

[0094] In one embodiment, the substrate W may be controlled to a given temperature instead of controlling the substrate support 11 to a given temperature. Controlling the temperature of the substrate W to a given temperature includes making the temperature of the substrate support 11, the heat transfer fluid flowing in the flow path 1110a, and / or the heater temperature a given temperature, or a temperature different from the given temperature.

[0095] (Step ST2: Formation of Metal-Containing Film)

[0096] In step ST2, a metal-containing film is formed on the mask MK. The metal-containing film MF may be formed on the upper surface TS and / or the side surface SS of the mask MK. The thickness of the metal-containing film MF formed on the side surface SS of the mask MK may be, for example, less than 10 nm, or may be less than 5 nm. The thickness of the metal-containing film MF formed on the side surface SS of the mask MK may also become thinner as it goes from the upper surface TS of the mask MK to the bottom of the opening OP. That is, the metal-containing film MF may also be a subconformal film. At the bottom of the opening OP of the mask MK, the metal-containing film MF may not be formed on the etching object film EF. The thickness of the metal-containing film MF formed at the bottom of the opening OP of the mask MK may also be thinner than the thickness of the metal-containing film MF formed on the upper surface TS and the side surface SS of the mask MK.

[0097] The metal-containing film MF may also be a conformal film. In this case, for example, the following step ST2 may be performed after the metal-containing film MF formed at the bottom of the opening OP is selectively removed by anisotropic etching. Thus, the metal-containing film MF remains on the upper surface TS and the side surface SS of the mask MK, while the metal-containing film MF at the bottom of the opening OP of the mask MK can be removed.

[0098] The metal-containing film MF may include at least one metal selected from the group consisting of tungsten (W), molybdenum (Mo), ruthenium (Ru), tin (Sn), titanium (Ti), tantalum (Ta), hafnium (Hf), chromium (Cr) and germanium (Ge), and may also include at least one metal selected from the group consisting of W, Mo, Ru and Sn, and may include a W-containing film. The metal-containing film MF may include carbides and / or silicides of the above-mentioned metals. In one example, the metal-containing film MF may include tungsten carbide (WC) and / or tungsten silicide (WSi).

[0099] The metal-containing film MF may be formed by chemical vapor deposition (CVD). Chemical vapor deposition may include plasma CVD. The metal-containing film MF may be formed using a process gas containing a metal-containing gas. The process gas is an example of a second process gas. In one embodiment, the metal-containing film MF may be formed by plasma generated from the process gas.

[0100] In the case of forming the metal-containing film MF by plasma CVD, first, a processing gas containing a metal-containing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. Next, a source RF signal is supplied to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13. As a result, a high-frequency electric field is generated between the shower head 13 and the substrate support 11, and plasma is generated from the processing gas in the plasma processing space 10s. At this time, a bias signal may not be supplied to the lower electrode of the substrate support 11. In addition, a bias signal may be supplied to the lower electrode of the substrate support 11. In this case, the level (power level or voltage level) of the bias signal may be lower than the level of the bias signal supplied to the substrate support 11 in step ST3. In addition, the bias signal may be a bias RF signal or a bias DC signal.

[0101] In one embodiment, during processing in step ST2, the temperature of the substrate support 11 or the substrate W can be controlled to the same temperature as the temperature set in step ST1, or can be controlled to a different temperature (for example, a temperature higher than the temperature set in step ST1).

[0102] In step ST2, the metal-containing gas contained in the processing gas can be a gas containing at least one metal selected from the group consisting of tungsten (W), molybdenum (Mo), ruthenium (Ru), tin (Sn), titanium (Ti), tantalum (Ta), hafnium (Hf), chromium (Cr) and germanium (Ge) (hereinafter also referred to as "metal M"). The gas containing metal M can be a gas containing an oxide, nitride, sulfide or halide of metal M. For example, the processing gas can be a gas containing a halide of metal M, or a gas containing a fluoride of metal M. In one example, the processing gas can contain WF6 gas, WCl6 gas, etc. In one example, the metal-containing gas can be WF2 gas, WF4 gas, WF5 gas, WF6 gas, WCl2 gas, WCl4 gas, WCl5 gas, WCl6 gas, MoF4 gas, MoCl6 gas, TiCl4 gas, etc. In one example, the metal-containing gas can be RuO3 gas, RuO4 gas, RuF5 gas, RuF6 gas. In one embodiment, the processing gas further includes an inert gas, such as Ar gas, He gas, Kr gas or other noble gas, or nitrogen gas.

[0103] In step ST2, the processing gas may further include an oxidizing gas or a reducing gas. As the oxidizing gas, oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), etc. may be used. As the reducing gas, a hydrogen-containing gas such as hydrogen (H2) may be used.

[0104] In step ST2, the processing gas may also include additional gases such as carbon-containing gas and silicon-containing gas. When the processing gas includes carbon-containing gas, a metal carbide film can be formed as the metal-containing film MF. For example, when the processing gas includes tungsten-containing gas and carbon-containing gas, a tungsten carbide film can be formed as the metal-containing film MF. The carbon-containing gas can be a hydrocarbon gas such as methane (CH4). In addition, when the processing gas includes silicon-containing gas, a metal silicide can be formed as the metal-containing film MF. For example, when the processing gas includes tungsten-containing gas and silicon-containing gas, a tungsten silicide film can be formed as the metal-containing film MF. The silicon-containing gas can be an aminosilane gas, etc.

[0105] Figure 6 1 is a diagram showing an example of a cross-sectional structure of a substrate W after processing in step ST2. Figure 6As shown, a metal-containing film MF is formed on the surface of the mask MK through the process in step ST2. The metal-containing film MF is a film containing the metal M contained in the process gas used in step ST2. In one embodiment, the metal-containing film MF is continuously formed from the upper surface TP of the mask MK to the side wall SS of the mask MK. In one embodiment, the metal-containing film MF may also be formed from the side wall SS of the mask MK to at least a portion of the bottom of the opening OP (the surface of the etching target film EF). The metal-containing film MF can provide protection for the mask MK during the etching of the etching target film EF in step ST3.

[0106] In step ST2 , the metal-containing film MF can be formed by atomic layer deposition (ALD) or molecular layer deposition (MLD).

[0107] In the case of forming the metal-containing film MF by ALD or MLD, a gas containing a precursor and a reaction gas are used as the processing gas. In this case, the substrate W can be exposed to a plasma generated from the reaction gas after being exposed to the gas containing the precursor. When the substrate W is exposed to the gas containing the precursor, the precursor gas is adsorbed on the surface of the mask MK to form a precursor layer. In this state, when the substrate W is exposed to the plasma generated from the reaction gas, the metal-containing film MF is formed from the precursor layer. In addition, after the substrate W is exposed to the gas containing the precursor and / or after being exposed to the plasma generated from the reaction gas, a noble gas or nitrogen gas can be supplied into the chamber to purge the remaining gas containing the precursor and the reaction gas. In addition, in the case of forming a sub-conformal metal-containing film MF on the surface of the mask MK by ALD or MLD, the supply of the gas containing the precursor can be stopped before the adsorption of the precursor to the surface of the mask MK is completed, or the reaction of the precursor layer with the reaction gas can be stopped before the formation of the metal-containing film MF from the precursor layer is completed.

[0108] The gas containing the precursor can be a metal-containing gas. As an example, the metal-containing gas can be the gas containing the metal M mentioned above. The reaction gas can be an oxidizing gas for oxidizing the precursor or a reducing gas for reducing the precursor. As an example, the oxidizing gas can be oxygen (O2), carbon monoxide (CO), carbon dioxide (CO2), etc. As an example, the reducing gas can be a hydrogen-containing gas such as hydrogen (H2).

[0109] In step ST2, when a metal-containing film is formed by ALD or MLD, in addition to the metal-containing gas mentioned above as the precursor gas, the processing gas may also include an additive gas such as a carbon-containing gas and / or a silicon-containing gas. In this case, the substrate W can be exposed alternately to the metal-containing gas and the additive gas. In addition, the substrate W can also be exposed to a mixed gas containing a metal-containing gas and an additive gas. In the case where the processing gas includes a carbon-containing gas as the additive gas, a metal carbide film can be formed as the metal-containing film MF. For example, in the case where the processing gas includes a tungsten-containing gas and a carbon-containing gas as the precursor gas, a tungsten carbide film can be formed as the metal-containing film MF. The carbon-containing gas can include hydrocarbon gases such as methane (CH4). In addition, in the case where the processing gas includes a silicon-containing gas as the additive gas, a metal silicide film can be formed as the metal-containing film MF. For example, in the case where the processing gas includes a tungsten-containing gas and a silicon-containing gas as the precursor gas, a tungsten silicide film can be formed as the metal-containing film MF. The silicon-containing gas can include aminosilane gas, etc.

[0110] In step ST2, the temperature of the substrate support 11 supporting the substrate W may be adjusted to be above 0°C, above 50°C, or above 100°C. The temperature of the substrate support 11 may be adjusted by the temperature of a heat transfer fluid flowing in a flow path provided in the substrate support 11, the temperature of a heater provided in the substrate support 11, or a lamp provided in the chamber. By forming the metal-containing film MF in a state where the temperature of the substrate support 11 is high, the selectivity of the mask MK (the ratio of the etching rate of the etching target film EF to the etching rate of the mask MK) can be improved in step ST3.

[0111] In one embodiment, the substrate W may be heat-treated after the metal-containing film MF is formed. By heat-treating the substrate W, the selectivity of the mask MK in the step ST3 can be improved even when the metal-containing film MF is formed at a low temperature. The heat treatment may be performed by heating the substrate W using the temperature of a heat transfer fluid flowing in a flow path provided in the substrate support portion 11, the temperature of a heater provided in the substrate support portion 11, or a lamp provided in the chamber. In the heat treatment, the temperature of the substrate W or the substrate support portion 11 may be set to be above 100° C. or above 150° C.

[0112] In step ST2, the metal-containing film MF can be formed on the mask MK by physical vapor deposition (PVD). As an example, physical vapor deposition can be performed as follows. First, a source RF signal is supplied to the lower electrode of the substrate support 11 and / or at least one upper electrode of the shower head 13. As a result, a high-frequency electric field is generated between the shower head 13 and the substrate support 11, and plasma is generated from the processing gas in the chamber 10. At this time, a bias signal can also be supplied to the upper electrode of the shower head 13. The upper electrode is an example of a metal-containing electrode. The timing of starting the supply of the bias signal can be the same as the timing of starting the supply of the source RF signal, or it can be different from the timing of starting the supply of the source RF signal. The bias signal can be a second DC signal generated by the second DC generating unit 32b. The second DC signal can be of negative polarity. When plasma is generated in the chamber 10, ions in the plasma are attracted to the surface of the shower head 13, which has become a negative potential, and collide with it. Then, the metal-containing material 132 constituting the surface of the shower head 13 is sputtered (physical sputtering) to emit metal and secondary electrons into the plasma. The emitted metal falls onto the substrate W. As a result, Figure 6 As shown, a metal-containing film MF containing the metal is formed on the surface of the mask MK. The metal-containing film MF can function as a protective film of the mask MK during the etching process. In addition, the secondary electrons emitted into the plasma can contribute to the increase in plasma density and the neutralization of the charged state of the substrate W. Thereby, the etching rate of the film EF and the verticality of the ions incident on the substrate W can be improved. In one embodiment, the bias signal supplied to the upper electrode can also be a bias RF signal. For example, the plasma processing device 1 can also be configured to electrically connect the second RF generating unit 31b to the upper electrode, and sputter the upper electrode by supplying the bias RF signal generated by the second RF generating unit 31b to the upper electrode.

[0113] (Step ST3: Etching of Etching Target Film)

[0114] In step ST3, the etching target film EF is etched by the processing gas. The processing gas is an example of the first processing gas. In one embodiment, the etching target film EF can be etched by being exposed to plasma generated from the processing gas through the mask MK formed with the metal-containing film MF.

[0115] In step ST3, a processing gas is supplied from the gas supply unit 20 to the plasma processing space 10s. Then, a source RF signal is supplied to the lower electrode of the substrate support unit 11 and / or the upper electrode of the shower head 13. As a result, a high-frequency electric field is generated between the shower head 13 and the substrate support unit 11, and plasma is generated from the processing gas in the plasma processing space 10s. In one embodiment, a bias signal may also be supplied to the lower electrode of the substrate support unit 11. As a result, active species such as ions and free radicals in the plasma are attracted to the substrate W, so that the recess RC of the etching object film EF is further etched in the depth direction. The bias signal may be a bias RF signal supplied from the second RF generating unit 31b. The bias signal may also be a bias DC signal supplied from the DC generating unit 32a.

[0116] The bias signal may be RF power for bias. In addition, a pulse voltage other than RF power may be applied to replace the RF power for bias. The pulse voltage is a pulse voltage supplied from a pulse power supply. The pulse power supply may be configured such that the power supply itself supplies a pulse wave, or may be provided with a device for pulsing the voltage on the downstream side of the pulse power supply. In one example, a pulse voltage is supplied to a substrate support to generate a negative potential on the substrate. The pulse voltage may be a pulse of a negative polarity DC voltage. In addition, the pulse voltage may be a rectangular wave pulse, a triangular wave pulse, an impulse, or a pulse having other voltage waveforms.

[0117] In one embodiment, during the processing in step ST3, the temperature of the substrate support 11 or the substrate W may be controlled to a given temperature set in step ST11. The temperature of the substrate support 11 or the substrate W in step ST3 may be controlled to be lower than the temperature of the substrate support 11 or the substrate W in step ST2. The temperature of the substrate support 11 or the substrate W may be set, for example, to 0°C or less, -10°C or less, -20°C or less, -30°C or less, -40°C or less, -50°C or less, -60°C or less, or -70°C or less. The temperature of the substrate support 11 or the substrate W may be controlled by the temperature of a heat transfer fluid flowing in a flow path provided in the substrate support 11, the temperature of a heater provided in the substrate support 11, or a lamp provided in the chamber.

[0118] By etching in step ST3, a recess is formed in the etching target film EF based on the shape of the opening OP of the mask MK. Then, when a given stop condition is satisfied, the etching in step ST3 is stopped, and the processing method ends. The stop condition can be set based on, for example, the etching time, the depth of the recess, etc. The aspect ratio of the recess RC at the end of etching can be, for example, greater than 20, or greater than 30, greater than 40, greater than 50, or greater than 100.

[0119] In step ST3, the processing gas may be selected based on the type of the etching target film EF. For example, when the etching target film EF is a silicon-containing film, the processing gas may include a fluorine-containing gas. The fluorine-containing gas may be, for example, hydrogen fluoride gas (HF gas), fluorocarbon gas, or hydrofluorocarbon gas.

[0120] In step ST3, when the processing gas includes HF gas, the flow rate (partial pressure) of HF gas in the processing gas can be the largest. In one example, the flow rate of HF gas in the processing gas other than the inert gas is the largest. In one example, the flow rate of HF gas can be 50% by volume or more, 60% by volume or more, 70% by volume or more, 80% by volume or more, 90% by volume or more, or 95% by volume or more relative to the total flow rate of the processing gas (the flow rate of all gases other than the inert gas when the processing gas includes an inert gas). The flow rate of HF gas can be less than 100% by volume, less than 99.5% by volume, less than 98% by volume, or less than 96% by volume relative to the total flow rate of the processing gas. In one example, the flow rate of HF gas is 70% by volume or more and 96% by volume or less relative to the total flow rate of the processing gas.

[0121] In step ST3, the processing gas may further include a phosphorus-containing gas. The phosphorus-containing gas is a gas containing phosphorus-containing molecules.

[0122] In one embodiment, the phosphorus-containing molecule may be tetraphosphorus decoxide (P4O 10 ), tetraphosphorus octoxide (P4O8), tetraphosphorus hexoxide (P4O6) and other oxides. Tetraphosphorus decoxide is sometimes called diphosphorus pentoxide (P2O5). Phosphorus-containing molecules may also be halides (phosphorus halides) such as phosphorus trifluoride (PF3), phosphorus pentafluoride (PF5), phosphorus trichloride (PCl3), phosphorus pentachloride (PCl5), phosphorus tribromide (PBr3), phosphorus pentabromide (PBr5), and phosphorus iodide (PI3). That is, phosphorus-containing molecules may also be phosphorus fluoride, etc., containing fluorine as a halogen element. Alternatively, phosphorus-containing molecules may also contain halogen elements other than fluorine as halogen elements. Phosphorus-containing molecules may also be phosphorus halides such as phosphoryl fluoride (POF3), phosphoryl chloride (POCl3), and phosphoryl bromide (POBr3). Phosphorus-containing molecules may also be phosphine (PH3), calcium phosphide (Ca3P2, etc.), phosphoric acid (H3PO4), sodium phosphate (Na3PO4), hexafluorophosphoric acid (HPF6), etc. Phosphorus-containing molecules can also be fluorophosphine (H g PF h). Here, the sum of g and h is 3 or 5. As fluorophosphine, HPF2 and H2PF3 are exemplified. The processing gas can contain one or more of the above-mentioned phosphorus-containing molecules as at least one phosphorus-containing molecule. For example, the processing gas can contain at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3, or PBr5 as at least one phosphorus-containing molecule. In addition, when each phosphorus-containing molecule contained in the processing gas is a liquid or a solid, each phosphorus-containing molecule can be supplied into the plasma processing space after being gasified by heating or the like.

[0123] In one embodiment, the phosphorus-containing gas may be PCl a F b (a is an integer greater than 1, b is an integer greater than 0, and a+b is an integer less than 5) gas or PC c H d F e (d and e are each an integer of 1 to 5, and c is an integer of 0 to 9) gas.

[0124] PCl a F b The gas may be, for example, at least one gas selected from the group consisting of PClF2 gas, PCl2F gas, and PCl2F3 gas.

[0125] PC c H d F e The gas may be, for example, at least one gas selected from the group consisting of PF2CH3 gas, PF(CH3)2 gas, PH2CF3 gas, PH(CF3)2 gas, PCH3(CF3)2 gas, PH2F gas and PF3(CH3)2 gas.

[0126] In one embodiment, the phosphorus-containing gas may also be PCl c F d C e H f (c, d, e and f are integers greater than 1, respectively) gas. In addition, the phosphorus-containing gas may be a gas containing P (phosphorus), F (fluorine) and a halogen other than F (fluorine) (e.g., Cl, Br or I) in its molecular structure, a gas containing P (phosphorus), F (fluorine), C (carbon) and H (hydrogen) in its molecular structure, or a gas containing P (phosphorus), F (fluorine) and H (hydrogen) in its molecular structure.

[0127] In one embodiment, the phosphorus-containing gas may be a phosphine-based gas. The phosphine-based gas may be phosphine (PH3), a compound obtained by replacing at least one hydrogen atom in phosphine with a suitable substituent, and a phosphonic acid derivative.

[0128] The substituent replacing the hydrogen atom of phosphine is not particularly limited, and may be, for example, a halogen atom such as a fluorine atom or a chlorine atom, an alkyl group such as a methyl group, an ethyl group, a propyl group, or a hydroxyalkyl group such as a hydroxymethyl group, a hydroxyethyl group, or a hydroxypropyl group. In one example, the substituent may be a chlorine atom, a methyl group, or a hydroxymethyl group.

[0129] The phosphonic acid derivative can be phosphonic acid (H3O2P), alkylphosphonic acid (PHO(OH)R), and dialkylphosphonic acid (PO(OH)R2).

[0130] The phosphine-based gas can, for example, be at least one gas selected from the group consisting of PCH3Cl2 (dichloro(methyl)phosphine) gas, P(CH3)2Cl (chloro(dimethyl)phosphine) gas, P(HOCH2)Cl2 (dichloro(hydroxymethyl)phosphine) gas, P(HOCH2)2Cl (chloro(dihydroxymethyl)phosphine) gas, P(HOCH2)(CH3)2(dimethyl(hydroxymethyl)phosphine) gas, P(HOCH2)2(CH3)(methyl(dihydroxymethyl)phosphine) gas, P(HOCH2)3(tris(hydroxymethyl)phosphine) gas, H3O2P (phosphonic acid) gas, PHO(OH)(CH3)(methylphosphonic acid) gas and PO(OH)(CH3)2(dimethylphosphonic acid) gas.

[0131] In step ST3 , the flow rate of the phosphorus-containing gas included in the processing gas may be 20 volume % or less, 10 volume % or less, or 5 volume % or less of the total flow rate of the processing gas.

[0132] In step ST3, the processing gas may further include a tungsten-containing gas. The tungsten-containing gas may be a gas containing tungsten and halogen. In one example, WF x Cl y Gas (x and y are integers greater than 0 and less than 6, respectively, and the sum of x and y is greater than 2 and less than 6). Specifically, the tungsten-containing gas can be a gas containing tungsten and fluorine, such as tungsten difluoride (WF2) gas, tungsten tetrafluoride (WF4) gas, tungsten pentafluoride (WF5) gas, tungsten hexafluoride (WF6) gas, tungsten dichloride (WCl2) gas, tungsten tetrachloride (WCl4) gas, tungsten pentachloride (WCl5) gas, tungsten hexachloride (WCl6) gas, etc. Gas containing tungsten and chlorine. Among them, it can also be at least any one of WF6 gas and WCl6 gas. The flow rate of the tungsten-containing gas can be less than 5% by volume of the total flow rate of the process gas. In addition, the process gas can also include at least one of titanium-containing gas, ruthenium-containing gas and / or molybdenum-containing gas as a supplement or substitute for the tungsten-containing gas.

[0133] In step ST3, the processing gas may also further include a carbon-containing gas. The carbon-containing gas may be a fluorocarbon gas and / or a hydrofluorocarbon gas. The fluorocarbon gas may, for example, be at least one gas selected from the group consisting of CF4 gas, C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 gas. The hydrofluorocarbon gas may, for example, be a gas selected from the group consisting of CHF3 gas, CH2F2 gas, CH3F gas, C2HF5 gas, C2H2F4 gas, C2H3F3 gas, C2H4F2 gas, C3HF7 gas, C3H2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, C5H2F8 gas, C5H2F6 gas, C5H2F 10 At least one gas selected from the group consisting of gas and C5H3F7 gas. In one embodiment, the carbon-containing gas is a straight-chain gas with unsaturated bonds. As such a gas, for example, it can be C3F6 (hexafluoropropylene) gas, C4F8 (octafluoro-1-butene, octafluoro-2-butene) gas, C3H2F4 (1,3,3,3-tetrafluoropropylene) gas, C4H2F6 (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas, C4F8O (pentafluoroethyl trifluorovinyl ether) gas, CF3COF gas (1,2,2,2-tetrafluoroethane-1-one), CHF2COF (difluoroacetyl fluoride) gas and COF2 (carbonyl fluoride) gas. In one embodiment, the carbon-containing gas may also contain halogen elements other than fluorine, and may also contain fluorine and halogen elements other than fluorine. Such a gas may be C i H j F k X l Here, X is a halogen other than fluorine. In addition, i and l may be integers greater than 1, and j and k may be integers greater than 0. The carbon-containing gas may contain, for example, CH j Cl l CF k Br l CF k I l , C i F k Cl l More specifically, the carbon-containing gas may be at least one selected from the group consisting of CHCl3, CH2Cl2, and CF2Br2.

[0134] In step ST3, the processing gas may further include an oxygen-containing gas. The oxygen-containing gas is, for example, at least one gas selected from the group consisting of O2, CO, CO2, H2O, and H2O2. In one example, the oxygen-containing gas is an oxygen-containing gas other than H2O, for example, at least one gas selected from the group consisting of O2, CO, CO2, and H2O2. The flow rate of the oxygen-containing gas can be adjusted according to the flow rate of other gases (e.g., carbon-containing gas) included in the processing gas.

[0135] In step ST3, the processing gas may also further include a gas containing halogens other than fluorine. The gas containing halogens other than fluorine may be a chlorine-containing gas, a bromine-containing gas and / or an iodine-containing gas. The chlorine-containing gas may be, in one example, at least one gas selected from the group consisting of HCl, Cl2, SiCl2, SiCl4, CCl4, SiH2Cl2, SI2Cl6, CHCl3, SO2Cl2, BCl3, PCl3, PCl5 and POCl3. The bromine-containing gas may be, in one example, at least one gas selected from the group consisting of Br2, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3 and BBr3. The iodine-containing gas may be, in one example, at least one gas selected from the group consisting of HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3. In one example, the gas containing halogens other than fluorine may be at least one gas selected from the group consisting of HCl gas, Cl2 gas, Br2 gas, and HBr gas. In one example, the gas containing halogens other than fluorine is HCl gas, Cl2 gas, or HBr gas.

[0136] In step ST3, the processing gas may further contain an inert gas. The inert gas is a noble gas such as Ar gas, He gas, Kr gas, and / or nitrogen gas.

[0137] In step ST3, the processing gas may include a gas capable of generating hydrogen fluoride species (HF species) in plasma instead of part or all of the HF gas. The HF species may include at least one of hydrogen fluoride gas, radicals, and ions.

[0138] The gas capable of generating HF species may be a single gas or a mixed gas containing hydrogen (H) and fluorine (F). The single gas containing H and F may be, for example, a hydrofluorocarbon gas. The carbon number of the hydrofluorocarbon gas may be 2 or more, 3 or more, or 4 or more. In one example, the hydrofluorocarbon gas is selected from CH2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, C5H2F 10The hydrofluorocarbon gas is at least one gas selected from the group consisting of CH2F2 gas, C3H2F4 gas, C3H2F6 gas and C4H2F6 gas.

[0139] The mixed gas containing H and F can be, for example, a mixed gas containing a hydrogen source and a fluorine source. The hydrogen source can be, for example, at least one gas selected from the group consisting of H2 gas, NH3 gas, H2O gas, H2O2 gas and hydrocarbon gas (CH4 gas, C3H6 gas, etc.). The fluorine source can be, for example, a fluorine-containing gas that does not contain carbon, such as NF3 gas, SF6 gas, WF6 gas or XeF2 gas. In addition, the fluorine source can also be a fluorine-containing gas that contains carbon, such as a fluorocarbon gas and a hydrofluorocarbon gas. In one example, the fluorocarbon gas can be at least one gas selected from the group consisting of CF4 gas, C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas and C5F8 gas. In one example, the hydrofluorocarbon gas can be at least one gas selected from the group consisting of CHF3 gas, CH2F2 gas, CH3F gas, C2HF5 gas and hydrofluorocarbon gases containing three or more Cs (C3H2F4 gas, C3H2F6 gas, C4H2F6 gas, etc.).

[0140] In addition, the processing gas used in step ST3 is not limited to the above-mentioned gas. For example, the processing gas described in U.S. Patent Registration No. 11,342,194 and International Publication No. 2021 / 090798 can also be applied.

[0141] In one embodiment, during the process in step ST3 , the type of gas contained in the process gas and its flow rate (partial pressure) may be fixed, or may be changed as the etching progresses.

[0142] Figure 7 1 is a diagram showing an example of a cross-sectional structure of a substrate W after processing in step ST3. Figure 7As shown, by the process of step ST3, the etching object film EF is etched in the depth direction. As described above, a metal-containing film MF containing metal M (ruthenium, tungsten, molybdenum and / or titanium) is formed on the mask MK in step ST2. The metal-containing film MF containing metal M has low reactivity with the active species of hydrogen fluoride in the plasma generated in step ST3. The etching resistance of the metal-containing film MF to the plasma generated in step ST3 is higher than that of the etching object film EF. The metal-containing film MF functions as a protective film of the mask MK in the etching in step ST3. As a result, the selectivity of the etching of the etching object film EF relative to the etching of the mask MK can be improved. In addition, for the etching object film EF, the generation of bow bending can be suppressed.

[0143] In addition, the metal-containing film MF may be removed after the step ST3 is completed. In one example, the metal-containing film MF is removed when the mask MK is removed after the step ST3 is completed. The mask MK may be removed by a dry process or a wet process.

[0144] According to one embodiment of the present disclosure, the etching target film EF is etched in a state where a metal-containing film MF is formed on the surface of the mask MK of the substrate W. The metal-containing film MF has a higher etching resistance to plasma than the mask MK. Therefore, when the etching target film EF is etched, the consumption of the mask MK can be suppressed. That is, the selectivity ratio in etching (the ratio of the etching rate of the etching target film EF to the etching rate of the mask MK) can be improved. In addition, by suppressing the consumption of the mask MK, the generation of a bow in the etching target film EF can be suppressed.

[0145] <Modification>

[0146] The method can be modified in various ways without departing from the scope and spirit of the present disclosure.

[0147] In one embodiment, step ST1 may include a step of forming the opening OP in the mask MK. That is, step ST1 may include a step of placing the substrate W having no opening OP formed in the mask MK on the substrate support 11 and a step of forming the opening OP in the mask MK.

[0148] In one embodiment, step ST1 may include a step of placing the substrate W having the metal-containing film MF formed on the mask MK on the substrate support 11. That is, in one embodiment, step ST3 may be performed after step ST1 is performed. In this case, step ST2 may be performed outside the plasma processing apparatus 1 before step ST1.

[0149] The plasma processing apparatus for performing steps ST1 to ST3 is not particularly limited, and various plasma processing apparatuses can be used. Figure 2 In addition to the capacitively coupled plasma processing apparatus shown, an inductively coupled plasma processing apparatus may be used, an ECR (electron cyclotron resonance) plasma processing apparatus may be used, or a combination of two or more of them may be used. For example, the process of forming a metal-containing film MF on the surface of the mask MK (process ST2) may be performed by an inductively coupled or capacitively coupled plasma processing apparatus, and the process of etching the etching target film EF (process ST3) may be performed by a capacitively coupled plasma processing apparatus. In addition, when an opening OP is formed in the mask MK in process ST1, the opening OP may be formed in the mask MK by an inductively coupled plasma processing apparatus.

[0150] In one embodiment, the steps ST2 and ST3 may be repeated. That is, the steps ST2 and ST3 may be combined into one cycle and the cycle may be repeated multiple times. In this case, the formation of the metal-containing film MF on the side wall SS of the mask MK and the etching of the etching target film EF are repeated alternately.

[0151] In one embodiment, the temperature of the substrate support 11 or the substrate W in the step ST2 and the step ST3 may be controlled by a cooler. Figure 8 This is a diagram showing an example of a cooler. Figure 8 The cooler shown includes: a high temperature tank 121, which stores a heat transfer fluid adjusted to a first temperature; and a low temperature tank 122, which stores a heat transfer fluid adjusted to a second temperature lower than the first temperature. The heat transfer fluid adjusted to the first temperature can be used to control the temperature of the substrate support 11 or the substrate W in step ST2. The heat transfer fluid adjusted to the second temperature can be used to control the temperature of the substrate support 11 or the substrate W in step ST3. That is, the cooler 120 can transport the heat transfer fluid adjusted to the first temperature from the high temperature tank 121 to the flow path 1110a in step ST2. Thereby, the temperature of the substrate support 11 or the substrate W can be controlled to a predetermined temperature. In addition, the cooler 120 can transport the heat transfer fluid adjusted to the second temperature from the low temperature tank 122 to the flow path 1110a in step ST3. Thereby, the temperature of the substrate support 11 or the substrate W can be controlled to a predetermined temperature. As an example, the high temperature tank 121 can store a heat transfer fluid at 180°C. As an example, the low temperature tank 122 can store a heat transfer fluid at -70°C.

[0152] <Experiment 1>

[0153] Fig. 9: is a table showing the experimental conditions and experimental results of Experiment 1. In Experiment 1, the improvement effect of the metal-containing film MF on improving the selectivity was confirmed. In Experiment 1, Sample 1 is a sample for confirming the etching rate of the carbon-containing film (mask MK). In addition, Samples 2 and 3 are samples for confirming the etching rate of the tungsten-containing film (metal-containing film MF).

[0154] In Sample 2, the tungsten-containing film was formed by setting the temperature of the substrate support 11 to 0° C. and generating plasma from a process gas containing WF6 gas and H2 gas. On the other hand, in Sample 3, the tungsten-containing film was formed by setting the temperature of the substrate support 11 to 120° C. and generating plasma from a process gas containing WF6 gas and H2 gas. In Samples 2 and 3, the tungsten-containing film was formed under the same conditions except for the temperature of the substrate support 11.

[0155] In addition, the carbon-containing film of Sample 1 and the tungsten-containing films of Samples 2 and 3 were etched by plasma generated from a process gas containing HF gas and phosphorus-containing gas.

[0156] like Fig. 9 As shown in FIG. 1 , the etching rate of the tungsten-containing film of sample 2 is significantly lower than the etching rate of the carbon-containing film of sample 1. It can be seen that by forming a metal-containing film MF such as a tungsten-containing film on the surface of the mask MK, the selectivity of the mask MK (the mask MK protected by the metal-containing film MF) with respect to the etching target film EF can be improved in the etching of the etching target film EF.

[0157] In addition, the etching rate of the tungsten-containing film of Sample 3 is further lower than the etching rate of the tungsten-containing film of Sample 2. It is thus confirmed that the selectivity of the mask MK (the mask MK protected by the metal-containing film MF) with respect to the etching target film EF can be further improved by controlling the temperature of the substrate support 11 or the substrate W when forming the metal-containing film MF.

[0158] <Experiment 2>

[0159] Fig.10 TABLE 2 is a table showing the experimental conditions and experimental results of Experiment 2. In Experiment 2, the effect of improving the selectivity by heat treatment of the metal-containing film MF was confirmed. In Experiment 2, Samples 4 and 5 were samples for confirming the etching rate of the tungsten-containing film (metal-containing film MF).

[0160] In samples 4 and 5, the tungsten-containing film is formed by generating plasma from a processing gas containing WF6 gas and H2 gas. In addition, in samples 4 and 5, the tungsten-containing film is formed by controlling the temperature of the substrate support portion 11 to 20° C. In addition, in sample 4, the tungsten-containing film is not heat-treated after being formed. On the other hand, in sample 5, the tungsten-containing film is heat-treated at 180° C. after being formed. In samples 4 and 5, the tungsten-containing film is formed under the same conditions except for the heat treatment.

[0161] In addition, the tungsten-containing films of Samples 4 and 5 were etched by plasma generated from a process gas containing COS gas and O 2 gas.

[0162] like Fig.10 As shown, the etching rate of the tungsten-containing film of the heat-treated sample 5 is significantly reduced compared to the etching rate of the tungsten-containing film of the non-heat-treated sample 4. It is thus confirmed that the selectivity of the mask MK (the mask MK protected by the metal-containing film MF) with respect to the etching target film EF can be improved by heat-treating the tungsten-containing film.

[0163] <Experiment 3>

[0164] Fig.11 : is a diagram showing the experimental results of Experiment 3. In Experiment 3, the improvement effect of the metal-containing film MF on improving the bow-shaped bending was confirmed. In Experiment 3, samples 6 and 7 are samples including a carbon-containing film (mask MK) having an opening OP formed on a silicon-containing film (etching target film EF). In Sample 6, a tungsten-containing film (metal-containing film MF) is not formed on the carbon-containing film. On the other hand, in Sample 7, a tungsten-containing film (metal-containing film MF) is formed on the carbon-containing film (mask MK). Samples 6 and 7 have the same structure except for the presence or absence of the tungsten-containing film.

[0165] In addition, in samples 6 and 7, the silicon-containing film was etched by plasma generated from a process gas containing HF gas and phosphorus-containing gas. Samples 6 and 7 were etched under the same conditions.

[0166] like Fig.11 As shown in FIG. 1 , in Sample 7, it was confirmed that the CD (Critical Dimension) of the concave portion RC formed on the silicon-containing film (etching target film EF) was improved in the upper portion of the concave portion RC compared to Sample 6. That is, in Sample 7, it was confirmed that the bow-shaped curvature of the concave portion RC was improved by forming the tungsten-containing film on the carbon-containing film. Fig.11 As shown, in Sample 7, it was confirmed that the CD of the opening OP formed in the carbon-containing film was improved.

[0167] The embodiments of the present disclosure may also include the following aspects.

[0168] (Supplementary Note 1) An etching method comprising:

[0169] Step (a), providing a substrate including a silicon-containing film and a mask on the silicon-containing film, wherein the mask includes an opening pattern;

[0170] Step (b), forming a metal-containing film on the mask; and

[0171] In step (c), plasma is generated from a first process gas including a hydrogen fluoride gas to etch the silicon-containing film.

[0172] (Supplementary Note 2) The etching method described in Supplementary Note 1, wherein:

[0173] The silicon-containing film includes a silicon oxide film, a silicon nitride film, a polysilicon film, or a stacked film including two or more of them.

[0174] (Supplement 3) The etching method according to Supplement 1 or 2, wherein:

[0175] The mask includes a silicon-containing film different from the silicon-containing film, or a carbon-containing film or a metal-containing film.

[0176] (Supplement 4) The etching method according to Supplement 1 or 2, wherein:

[0177] The mask includes an amorphous carbon film or a spin-on carbon film.

[0178] (Supplement 5) The etching method according to Supplement 1 or 2, wherein:

[0179] The mask includes a film including at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium, or an oxide film, a nitride film, or a carbide film including the at least one metal.

[0180] (Supplementary Note 6) The etching method according to any one of Supplementary Notes 1 to 5, wherein

[0181] The (b) includes forming the metal-containing film from a second process gas including a metal-containing gas.

[0182] (Supplementary Note 7) The etching method described in Supplementary Note 6, wherein:

[0183] The metal-containing gas includes at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.

[0184] (Supplementary Note 8) The etching method described in Supplementary Note 7, wherein:

[0185] The metal-containing gas includes tungsten hexafluoride or molybdenum hexafluoride.

[0186] (Supplementary Note 9) The etching method according to any one of Supplementary Notes 6 to 8, wherein

[0187] The (b) includes generating plasma from the second process gas to form the metal-containing film.

[0188] (Supplement 10) The etching method described in Supplement 1, wherein:

[0189] The (b) includes allowing a metal-containing precursor to adsorb onto the mask to form the metal-containing film.

[0190] (Supplement 11) The etching method according to Supplement 10, wherein:

[0191] The (b) includes generating plasma from a gas that oxidizes or reduces at least a portion of the metal-containing precursor adsorbed on the mask to form the metal-containing film.

[0192] (Supplementary Note 12) The etching method described in Supplementary Note 11, wherein:

[0193] In the (b), a portion of the metal-containing precursor adsorbed to the mask is not oxidized or reduced.

[0194] (Supplement 13) The etching method according to any one of Supplements 1 to 8, wherein

[0195] The (b) includes forming the metal-containing film by physical evaporation.

[0196] (Supplement 14) The etching method according to Supplement 13, wherein:

[0197] The step (a) includes placing the substrate on a substrate support portion,

[0198] The (b) includes forming the metal-containing film by sputtering a metal-containing electrode disposed opposite to the substrate support portion.

[0199] (Supplement 15) The etching method according to any one of Supplements 1 to 9, wherein

[0200] The first process gas further comprises a phosphorus-containing gas.

[0201] (Supplement 16) The etching method according to Supplement 15, wherein:

[0202] The phosphorus-containing gas includes phosphorus halide or phosphorus chloride.

[0203] (Supplementary Note 17) The etching method according to any one of Supplementary Notes 1 to 9, wherein

[0204] The first process gas includes a carbon-containing gas.

[0205] (Supplementary Note 18) The etching method according to any one of Supplementary Notes 1 to 9, wherein

[0206] The first process gas further comprises a halogen-containing gas.

[0207] (Supplement 19) The etching method according to any one of Supplements 1 to 9, wherein

[0208] The first process gas includes at least one gas selected from the group consisting of an oxygen-containing gas, a boron-containing gas, and a metal-containing gas.

[0209] (Supplementary Note 20) The etching method according to any one of Supplementary Notes 1 to 9, wherein

[0210] The flow rate of the hydrogen fluoride gas is the largest among the first process gases.

[0211] (Supplementary Note 21) The etching method according to any one of Supplementary Notes 1 to 20, wherein

[0212] In the above (b), the temperature of the substrate support portion supporting the substrate is set to a first temperature,

[0213] In (c) above, the temperature of the substrate support portion is set to a second temperature lower than the first temperature.

[0214] (Supplementary Note 22) The etching method according to Supplementary Note 21, wherein:

[0215] The first temperature is above 0°C, and the second temperature is below 0°C.

[0216] (Supplementary Note 23) The etching method according to any one of Supplementary Notes 1 to 22, wherein

[0217] The cycle including the steps (b) and (c) is repeated multiple times.

[0218] (Supplementary Note 24) An etching method comprising:

[0219] Step (a), preparing a substrate including a silicon-containing film and a mask on the silicon-containing film, wherein the mask includes an opening pattern;

[0220] Step (b), forming a metal-containing film on the mask; and

[0221] In step (c), plasma is generated from the first process gas to etch the silicon-containing film.

[0222] (Supplementary Note 25) The etching method described in Supplementary Note 24, wherein:

[0223] The first process gas includes one or more gases that generate a plasma including a hydrogen fluoride species when the plasma is generated from the first process gas.

[0224] (Supplementary Note 26) A plasma processing device comprising a chamber and a control unit, wherein:

[0225] The control unit is configured to perform the following control:

[0226] Control (a), preparing a substrate including a silicon-containing film and a mask on the silicon-containing film in the chamber, the mask including an opening pattern;

[0227] controlling (b) to form a metal-containing film on the mask; and

[0228] and controlling (c) generating plasma from a first process gas including a hydrogen fluoride gas to etch the silicon-containing film.

[0229] The above embodiments are described for the purpose of explanation and are not intended to limit the scope of the present disclosure. The above embodiments can be variously modified without departing from the scope and purpose of the present disclosure. For example, a part of the constituent elements in a certain embodiment can be added to other embodiments. In addition, a part of the constituent elements in a certain embodiment can be replaced with corresponding constituent elements in other embodiments.

[0230] Description of Reference Numerals

[0231] 1: plasma processing apparatus; 11: substrate support portion; EF: etching target film; MF: metal-containing film; MK: mask; OP: opening; W: substrate.

Claims

1. An etching method, comprising: Step (a), providing a substrate including a silicon-containing film and a mask on the silicon-containing film, wherein the mask includes an opening pattern; Step (b), forming a metal-containing film on the mask; and In step (c), plasma is generated from a first process gas including a hydrogen fluoride gas to etch the silicon-containing film.

2. The etching method according to claim 1, wherein: The silicon-containing film includes a silicon oxide film, a silicon nitride film, a polysilicon film, or a stacked film including two or more of them.

3. The etching method according to claim 1, wherein: The mask includes a silicon-containing film different from the silicon-containing film, or a carbon-containing film or a metal-containing film.

4. The etching method according to claim 1, wherein: The mask includes an amorphous carbon film or a spin-on carbon film.

5. The etching method according to claim 1, wherein: The mask includes a film including at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium, or an oxide film, a nitride film, or a carbide film including the at least one metal.

6. The etching method according to claim 1, wherein: The step (b) includes forming the metal-containing film from a second process gas including a metal-containing gas.

7. The etching method according to claim 6, wherein: The metal-containing gas includes at least one metal selected from the group consisting of tungsten, molybdenum, titanium, and ruthenium.

8. The etching method according to claim 7, wherein: The metal-containing gas includes tungsten hexafluoride or molybdenum hexafluoride.

9. The etching method according to claim 6, wherein: The step (b) includes generating plasma from the second process gas to form the metal-containing film.

10. The etching method according to claim 1, wherein: The step (b) includes allowing a metal-containing precursor to adsorb onto the mask to form the metal-containing film.

11. The etching method according to claim 10, wherein: The step (b) includes generating plasma from a gas that oxidizes or reduces at least a portion of the metal-containing precursor adsorbed on the mask to form the metal-containing film.

12. The etching method according to claim 11, wherein: In the step (b), a portion of the metal-containing precursor adsorbed on the mask is not oxidized or reduced.

13. The etching method according to claim 1, wherein: The step (b) includes forming the metal-containing film by physical vapor deposition.

14. The etching method according to claim 13, wherein: The step (a) includes placing the substrate on a substrate support portion, The step (b) includes forming the metal-containing film by sputtering a metal-containing electrode disposed to face the substrate support portion.

15. The etching method according to claim 1, wherein: The first process gas further comprises a phosphorus-containing gas.

16. The etching method according to claim 15, wherein: The phosphorus-containing gas includes phosphorus halide or phosphorus chloride.

17. The etching method according to claim 1, wherein: The first process gas includes a carbon-containing gas.

18. The etching method according to claim 1, wherein: The first process gas further comprises a halogen-containing gas.

19. The etching method according to claim 1, wherein: The first process gas includes at least one gas selected from the group consisting of an oxygen-containing gas, a boron-containing gas, and a metal-containing gas.

20. The etching method according to claim 1, wherein: The flow rate of the hydrogen fluoride gas is the largest among the first process gases.

21. The etching method according to any one of claims 1 to 20, wherein: In the step (b), the temperature of the substrate support portion supporting the substrate is set to a first temperature, In the step (c), the temperature of the substrate support portion is set to a second temperature lower than the first temperature.

22. The etching method according to claim 21, wherein: The first temperature is above 0°C, and the second temperature is below 0°C.

23. The etching method according to claim 1, wherein: The cycle including the step (b) and the step (c) is repeated multiple times.

24. An etching method comprising: Step (a), preparing a substrate including a silicon-containing film and a mask on the silicon-containing film, wherein the mask includes an opening pattern; Step (b), forming a metal-containing film on the mask; as well as In step (c), plasma is generated from the first process gas to etch the silicon-containing film.

25. The etching method according to claim 24, wherein: The first process gas includes one or more gases that generate a plasma including a hydrogen fluoride species when the plasma is generated from the first process gas.

26. A plasma processing device comprising a chamber and a control unit, wherein: The control unit is configured to perform the following control: Control (a), preparing a substrate including a silicon-containing film and a mask on the silicon-containing film in the chamber, the mask including an opening pattern; controlling (b) to form a metal-containing film on the mask; as well as and controlling (c) generating plasma from a first process gas including a hydrogen fluoride gas to etch the silicon-containing film.

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