Etching method and plasma processing system

Abstract

Provided is a technology that suppresses the blockage of openings in a mask. Provided is an etching method including: (a) a step in which a substrate is provided inside of a chamber, the substrate includes a first film and a second film that defines openings on the first film, the first film is a multilayered film that includes a first layer including silicon and oxygen, and includes a second layer including silicon and nitrogen, and the second film includes a metal-containing film or a carbon-containing film; (b) a step in which a protective film is formed on the surface of the second film by plasma generated from a first processing gas which contains a deposition gas, and the pressure inside the chamber is controlled to 30 mTorr or less; and (c) a step in which the first film is etched via the second film on which the protective film has been formed, by using plasma generated from a second processing gas which contains a hydrogen fluoride gas.

Description

Etching method and plasma processing system

[0001] SUMMARY Exemplary embodiments of the present disclosure relate to an etching method and a plasma processing system.

[0002] Patent Document 1 discloses that after etching a silicon-containing film partway using plasma in an etching apparatus, a carbon-containing film is formed on the silicon-containing film without generating plasma in a film-forming apparatus.

[0003] Japanese Patent Application Laid-Open No. 2016-21546

[0004] The present disclosure provides a technique for preventing mask opening occlusion.

[0005] In one exemplary embodiment of the present disclosure, there is provided an etching method including: (a) providing a substrate into a chamber, the substrate including a first film and a second film defining an opening on the first film, the first film being a stacked film including a first layer containing silicon and oxygen and a second layer containing silicon and nitrogen, and the second film including a metal-containing film or a carbon-containing film; (b) forming a protective film on a surface of the second film by plasma generated from a first process gas including a deposition gas, wherein the pressure in the chamber is controlled to 30 mTorr or less; and (c) etching the first film through the second film on which the protective film has been formed by plasma generated from a second process gas including hydrogen fluoride gas.

[0006] According to one exemplary embodiment of the present disclosure, a technique for suppressing occlusion of an opening in a mask can be provided.

[0007] 8A is a diagram for explaining an example of the configuration of a plasma processing system. FIG. 8B is a diagram for explaining an example of the configuration of a capacitively coupled plasma processing apparatus. FIG. 8C is a diagram for explaining an example of blocking an opening in a mask. FIG. 8D is a flowchart showing an example of the method MT. FIG. 8E is a diagram showing an example of the cross-sectional structure of a substrate W. FIG. 8F is a diagram showing an example of a first protective film PF formed on the surface of a mask MK. FIG. 8F is a diagram for explaining an example of a substrate W during etching. FIG. 8G is a flowchart showing another example of the method MT. FIG. 8H is a flowchart showing an example of the method MT. FIG. 8H is a flowchart showing an example of the process ST12 and the process ST13 in FIG. 8A. FIG. 8I is a diagram showing an example of the cross-sectional structure of a substrate W1.

[0008] Hereinafter, each embodiment of the present disclosure will be described.

[0009] In one exemplary embodiment, there is provided an etching method including: (a) providing a substrate into a chamber, the substrate including a first film and a second film defining an opening on the first film, the first film being a stacked film including a first layer containing silicon and oxygen and a second layer containing silicon and nitrogen, and the second film including a metal-containing film or a carbon-containing film; (b) forming a protective film on a surface of the second film by plasma generated from a first process gas including a deposition gas, wherein the pressure in the chamber is controlled to 30 mTorr or less; and (c) etching the first film through the second film on which the protective film has been formed by plasma generated from a second process gas including hydrogen fluoride gas.

[0010] In one exemplary embodiment, the first film includes a first region where first and second layers are alternately stacked, and a second region on the first region, the second region including a third layer including silicon and nitrogen, the first layer being thicker than the second layer, and the third layer being thicker than the second layer.

[0011] In one exemplary embodiment, the second film comprises at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium.

[0012] In one exemplary embodiment, the second film comprises a metal and at least one element selected from the group consisting of silicon, carbon, nitrogen, oxygen, boron, hydrogen, and phosphorus.

[0013] In one exemplary embodiment, the opening size of the opening is 50 nm or less.

[0014] In one exemplary embodiment, (b) and (c) are performed simultaneously.

[0015] In one exemplary embodiment, the flow rate of the hydrogen fluoride gas in the second process gas is greater than the flow rate of the deposition gas in the first process gas.

[0016] In one exemplary embodiment, the cycle including (b) and (c) is repeated.

[0017] In one exemplary embodiment, in (a), a substrate is placed on a substrate support in a chamber, and in (b) and (c), the temperature of the substrate or the substrate support is controlled to 0° C. or below.

[0018] In one exemplary embodiment, the deposition gas comprises at least one gas selected from the group consisting of a carbon-containing gas, a silicon-containing gas, and a phosphorus-containing gas.

[0019] In one exemplary embodiment, the first process gas further comprises a hydrogen-containing gas other than the deposition gas.

[0020] In one exemplary embodiment, the second process gas further comprises a nitrogen-containing gas.

[0021] In one exemplary embodiment, the nitrogen-containing gas is N ２ Gas, NF ３ Gas, NH ３ gas, NO gas and NO ２ The gas contains at least one selected from the group consisting of:

[0022] In one exemplary embodiment, (c) includes (c1) a period of generating a plasma from a second process gas further comprising a nitrogen-containing gas at a first flow rate, and (c2) a period of generating a plasma from a second process gas further comprising a nitrogen-containing gas at a second flow rate that does not include a nitrogen-containing gas or is less than the first flow rate.

[0023] In one exemplary embodiment, the second process gas further comprises a phosphorus-containing gas.

[0024] In one exemplary embodiment, the second process gas further comprises at least one gas selected from the group consisting of a metal-containing gas, a carbon-free fluorine-containing gas, a halogen-containing gas other than fluorine, an oxygen-containing gas, and a boron-containing gas.

[0025] In one exemplary embodiment, in (c), the etching of the second layer is performed under the same conditions as the etching of the first layer.

[0026] In one exemplary embodiment, in (c), the etching of the second layer is performed under different conditions than the etching of the first layer.

[0027] In one exemplary embodiment, in (c), a first etching gas and a second etching gas different from the first etching gas are used as the second processing gas, and (c) includes: (c1) etching the first layer with plasma generated from the first etching gas; and (c2) etching the second layer with plasma generated from the second etching gas.

[0028] In one exemplary embodiment, an etching method is provided, including: (a) providing a substrate in a chamber, the substrate including a first film and a metal-containing mask on the first film, the first film including a first layer including the first silicon-containing film, a second layer including a second silicon-containing film different from the first silicon-containing film, and a third layer including a third silicon-containing film different from the first silicon-containing film and the second silicon-containing film, the third layer being disposed above the first layer and the second layer and having a thickness different from that of the first layer, the metal-containing mask including an opening pattern with an opening dimension of 50 nm or less; (b) forming a protective film on a surface of the metal-containing mask with plasma generated from a first process gas including a deposition gas, wherein the pressure in the chamber is controlled to 30 mTorr or less; and (c) etching the first film through the metal-containing mask with the protective film formed thereon with plasma generated from a second process gas, wherein the second process gas includes one or more gases capable of generating hydrogen fluoride in plasma.

[0029] In one exemplary embodiment, the first film comprises a laminated film in which first and second layers are alternately stacked.

[0030] In one exemplary embodiment, the first layer is silicon dioxide, the second layer is silicon nitride, and the third layer is silicon carbonitride.

[0031] In one exemplary embodiment, there is provided a plasma processing system including a plasma processing apparatus having a chamber and a controller, the controller being configured to perform the following: (a) controlling a substrate to be provided into the chamber, the substrate including a first film and a second film defining an opening on the first film, the first film being a stacked film including a first layer containing silicon and oxygen and a second layer containing silicon and nitrogen, the second film including a metal-containing film or a carbon-containing film; (b) controlling a plasma generated from a first process gas including a deposition gas to form a protective film on a surface of the second film, the plasma generated from the first process gas including a deposition gas, the pressure in the chamber being controlled to 30 mTorr or less; and (c) controlling a plasma generated from a second process gas including hydrogen fluoride gas to etch the first film through the second film on which the protective film has been formed.

[0032] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are designated by the same reference numerals, and redundant explanations will be omitted. Unless otherwise specified, the positional relationships, such as up, down, left, and right, will be 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.

[0033] <Configuration Example of Plasma Processing System> FIG. 1 is a diagram illustrating a configuration example of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also 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 a gas supply unit 20 (described later), and the gas exhaust port is connected to an exhaust system 40 (described later). The substrate support 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0034] The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma generated in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), electron-cyclotron-resonance plasma (ECR plasma), helicon wave plasma (HWP), surface wave plasma (SWP), or the like. Various types of plasma generators may be used, including alternating current (AC) plasma generators and direct current (DC) plasma generators. In one embodiment, the AC signal (AC power) used in the AC plasma generator has a frequency in the range of 100 kHz to 10 GHz. Thus, AC signals include radio frequency (RF) signals and microwave signals. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0035] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. This program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The processing unit 2a1 may be a CPU (Central Processing Unit). The storage unit 2a2 may include a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0036] The following describes a configuration example of a capacitively coupled plasma processing apparatus as an example of the plasma processing apparatus 1. Fig. 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0037] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms 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 showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0038] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the ring assembly 112.

[0039] In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Furthermore, at least one RF / DC electrode coupled to an RF power supply 31 and / or a DC power supply 32, which will be described later, may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or a DC signal, which will be described later, is supplied to the at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple lower electrodes. Furthermore, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support 11 includes at least one lower electrode.

[0040] The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

[0041] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the backside of the substrate W and the central region 111a.

[0042] The showerhead 13 is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The process gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0043] 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 showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

[0044] 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. This generates a plasma 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 generation unit 12. Furthermore, by supplying a bias RF signal to the at least one lower electrode, a bias potential is generated on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0045] 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 be configured to generate multiple 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.

[0046] The second RF generator 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 100 kHz to 60 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0047] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to the at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to the at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

[0048] In various embodiments, the first and second DC signals may 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 pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the 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. When 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 pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0049] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0050] <Example of Mask Opening Closure> FIG. 3 is a diagram illustrating an example of mask opening closure. FIG. 3 illustrates an example of a cross-sectional structure in which a silicon-containing film SF is etched through a mask MK using plasma generated from an etching gas containing hydrogen fluoride gas. The mask MK is, for example, a metal-containing mask. As shown in FIG. 3 , among the reaction products derived from the mask MK generated by etching, some product X volatilizes, while some product Y does not volatilize and may reattach to the mask MK. For example, if the mask MK contains tungsten silicide (WSi), product X may be silicon fluoride, and product Y may be tungsten or a compound containing tungsten. As the amount of product Y reattaching to the mask MK increases, the opening OP in the mask MK is blocked. As a result, the etchant is not transported into the opening OP, and etching stops. Blockage of the opening in the mask MK can occur, for example, when the volatility of the reaction products decreases in a low-temperature environment (for example, below 0°C), when the etching time is long and the amount of reaction products increases, or when the opening dimensions of the opening OP are small.

[0051] An etching method according to an exemplary embodiment of the present disclosure (hereinafter also referred to as "method MT") can suppress blocking of openings in a mask. Hereinafter, the method will be described with reference to the drawings.

[0052] <Example of Method MT> Fig. 4 is a flowchart showing an example of method MT. As shown in Fig. 4, method MT includes a step ST11 of providing a substrate, a step ST12 of forming a protective film, and a step ST13 of etching. The treatments in each step may be performed in the plasma processing system shown in Fig. 1 or 2. The following describes an example in which the control unit 2 controls each part of the plasma processing apparatus 1 shown in Fig. 2 to perform method MT on a substrate W.

[0053] (Process ST11: Providing a Substrate) In process ST11, a substrate W is provided to a plasma processing chamber 10 (hereinafter also referred to as "chamber 10"). The substrate W is carried into the chamber 10 by a transport arm, placed on a substrate support 11 by a lifter, and held by suction on the substrate support 11 as shown in FIG. 2 .

[0054] 5 is a diagram showing an example of the cross-sectional structure of a substrate W. The substrate W includes a silicon-containing film SF and a mask MK disposed on the silicon-containing film SF. The silicon-containing film SF may be formed on an undercoat film UF. The silicon-containing film SF is an example of a first film of the present disclosure. The mask MK is an example of a second film of the present disclosure. The substrate W may be used in the manufacture of semiconductor devices. Semiconductor devices include, for example, memory devices such as DRAMs and 3D-NAND flash memories, and logic devices. In one embodiment, the substrate W may be a substrate for DRAMs.

[0055] The base film UF is, for example, a silicon wafer, an organic film formed on a silicon wafer, a dielectric film, a metal film, a semiconductor film, etc. The base film UF may be configured by stacking a plurality of films.

[0056] The silicon-containing film SF is a film to be etched by the method MT. In one embodiment, the silicon-containing film SF is a stacked film including a first layer including silicon and oxygen and a second layer including silicon and nitrogen. The first layer may be, for example, a silicon oxide film. The second layer may be, for example, a silicon nitride film. The first layer and / or the second layer may be doped with an element such as phosphorus, boron, or nitrogen.

[0057] In one embodiment, the silicon-containing film SF may be formed by stacking at least two or more types of films selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon carbonitride film, a polycrystalline silicon film, and a carbon-containing silicon film. For example, the silicon-containing film SF may be formed by alternately stacking silicon oxide films and silicon nitride films. For example, the silicon-containing film SF may be formed by alternately stacking silicon oxide films and polycrystalline silicon films. For example, the silicon-containing film SF may be a stacked film including a silicon nitride film, a silicon oxide film, and a polycrystalline silicon film. For example, the silicon-containing film SF may be formed by stacking a silicon oxide film and a silicon carbonitride film. For example, the silicon-containing film SF may be a stacked film including a silicon oxide film, a silicon nitride film, and a silicon carbonitride film. In one embodiment, at least a portion of the silicon-containing film SF may be doped with an element such as phosphorus, boron, or nitrogen.

[0058] In one embodiment, the mask MK includes a metal-containing film or a carbon-containing film. The mask MK may be a single-layer mask made of one type of film, or may be a multi-layer mask made of two or more films.

[0059] In one embodiment, the metal-containing film constituting the mask MK contains at least one metal (hereinafter also referred to as "metal M") selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium. In one embodiment, the metal-containing film contains metal M and at least one element selected from the group consisting of silicon, carbon, nitrogen, oxygen, boron, hydrogen, and phosphorus. For example, the metal-containing film may be at least one selected from the group consisting of WC (tungsten carbide), WSi (tungsten silicide), WSiN, and WSiC.

[0060] In one embodiment, the carbon-containing film constituting the mask MK is an amorphous carbon film, a spin-on carbon (SOC) film, or a photoresist film. The amorphous carbon (ACL) film may be doped with an element such as boron, and may be, for example, a boron-containing amorphous carbon film (B-doped ACL), an arsenic-containing amorphous carbon film (As-doped ACL), a tungsten-containing amorphous carbon film (W-doped ACL), or a xenon-containing amorphous carbon film (Xe-doped ACL).

[0061] 5, the mask MK defines at least one opening OP on the silicon-containing film SF. The opening OP is a space above the silicon-containing film SF and is surrounded by a sidewall SW of the mask MK. That is, the upper surface of the silicon-containing film SF has a region covered by the mask MK and a region exposed at the bottom of the opening OP.

[0062] The openings OP may have any shape when viewed from above the substrate W, i.e., when the substrate W is viewed from top to bottom in FIG. 5 . The shape may be, for example, a circle, an ellipse, a rectangle, a line, or a combination of one or more of these. The mask MK may have multiple side walls that define multiple openings OP. This allows the mask MK to have an opening pattern. For example, the mask MK may form a line-and-space pattern by arranging multiple openings OP in a planar line-of-sight pattern with a gap between them. Alternatively, the mask MK may form an array pattern by arranging multiple circular openings OP in a dot pattern. In one embodiment, the opening dimension of the openings OP may be 50 nm or less, 40 nm or less, 30 nm or less, or 20 nm or less.

[0063] The base film UF, silicon-containing film SF, and mask MK may each be formed by any method. For example, the base film UF, silicon-containing film SF, and mask MK may be formed by a CVD method, an ALD method, a PVD method, a spin coating method, or the like. The mask MK may be formed by, for example, lithography. The opening OP in the mask MK may be formed by etching the mask MK. The base film UF, silicon-containing film SF, and mask MK may each be a flat film or a film having an uneven surface. The substrate W may further include another film below the base film UF. In this case, recesses having shapes corresponding to the openings OP may be formed in the silicon-containing film SF and base film UF and used as masks for etching the other film.

[0064] At least a part of the process of forming the base film UF, the silicon-containing film SF, and the mask MK of the substrate W may be performed in the chamber 10 as part of step ST11. For example, when the opening OP of the mask MK is formed by etching, the etching in step ST11 and the processes of steps ST12 and ST13 may be performed consecutively in the chamber 10. In one embodiment, the substrate W may be provided in the chamber 10 after all or part of the substrate W is formed in an apparatus or chamber external to the plasma processing apparatus 1.

[0065] In one embodiment, after the substrate W is provided in the central region 111a of the substrate support 11, the substrate support 11 is controlled to a first temperature by a temperature control module. The first temperature may be, for example, 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. In one example, controlling the temperature of the substrate support 11 to the first temperature includes setting the temperature of the heat transfer fluid flowing through the flow path 1110a or the heater temperature to the first temperature, or setting them to a temperature different from the first temperature. Note that the timing at which the heat transfer fluid starts to flow through the flow path 1110a may be before, after, or simultaneously with the substrate W being placed on the substrate support 11. Alternatively, the temperature of the substrate support 11 may be controlled to the first temperature before step ST11. That is, the substrate W may be provided to the substrate support 11 after the temperature of the substrate support 11 is controlled to the first temperature.

[0066] In one embodiment, the substrate W may be controlled to the first temperature instead of controlling the substrate support 11 to the first temperature. Controlling the temperature of the substrate W to the first temperature includes setting the temperature of the substrate support 11, the heat transfer fluid flowing through the flow path 1110a, and / or the heater temperature to the first temperature or to a temperature different from the first temperature.

[0067] (Process ST12: Formation of Protective Film) In process ST12, a protective film (hereinafter also referred to as a "first protective film") is formed on the surface of the mask MK using plasma generated from a first process gas including a deposition gas. Process ST12 includes supplying the first process gas to the chamber 10 and generating plasma from the first process gas.

[0068] In one embodiment, during the treatment in step ST12, the temperature of the substrate support member 11 or the substrate W may be controlled to the above-mentioned first temperature, or may be controlled to a second temperature different from the first temperature. In one embodiment, the second temperature is 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.

[0069] In one embodiment, during the process in step ST12, the pressure in the chamber 10 may be controlled to a first pressure. The first pressure may be 30 mTorr or less, 20 mTorr or less, or 15 mTorr or less. The first pressure may be 1 mTorr or more.

[0070] In step ST12, a first process gas is supplied into the chamber 10. The first process gas may be supplied into the chamber 10 from the gas supply unit 20 via the gas inlet 13c of the shower head 13, for example. In one embodiment, the first process gas includes a deposition gas. The deposition gas may include at least one gas selected from the group consisting of a carbon-containing gas, a silicon-containing gas, and a phosphorus-containing gas.

[0071] The carbon-containing gas may be, for example, a hydrocarbon gas. ４ Gas, C ２ H ２ Gas, C ２ H ４ Gas and C ３ H ６ The carbon-containing gas may be at least one selected from the group consisting of carbon-containing gases, for example, fluorocarbon gases, such as CF ４ Gas, C ２ F ２ Gas, C ２ F ４ Gas, C ３ F ６ Gas, C ３ F ８ Gas, C ４ F ６ Gas, C ４ F ８ Gas and C ５ F ８ The carbon-containing gas may be at least one selected from the group consisting of carbon-containing gases. The carbon-containing gas may be, for example, a hydrofluorocarbon gas. The hydrofluorocarbon gas may be, for example, CHF ３ Gas, CH ２ F ２ Gas, CH ３ F gas, C ２ HF ５ Gas, C ２ H２ F ４ Gas, C ２ H ３ F ３ Gas, C ２ H ４ F ２ Gas, C ３ HF ７ Gas, C ３ H ２ F ２ Gas, C ３ H ２ F ４ Gas, C ３ H ２ F ６ Gas, C ３ H ３ F ５ Gas, C ４ H ２ F ６ Gas, C ４ H ５ F ５ Gas, C ４ H ２ F ８ Gas, C ５ H ２ F ６ Gas, C ５ H ２ F １０ Gas and C ５ H ３ F ７ The gas may be at least one selected from the group consisting of gases.

[0072] The silicon-containing gas is, for example, SiF ４ Gas, SiCl ４ Gas and SiH ４ At least one selected from the group consisting of:

[0073] The phosphorus-containing gas may be, for example, a halogenated phosphorus gas. The halogenated phosphorus gas may be, for example, PF ３ Gas and PF ５ The halogenated phosphorus gas may be, for example, a phosphorus fluoride gas containing fluorine as a halogen element. ３ Gas and PCl ５ The halogenated phosphorus gas may be, for example, phosphorus chloride gas containing chlorine as a halogen element. ３ Gas, PBr５ Gas, PI ３ The halogen element may be a gas containing bromine or iodine, such as a phosphorus halide gas, for example, PClF ２ Gas, PCl ２ F gas, PCl ２ F ３ The halogenated phosphorus gas may be, for example, phosphorus oxyfluoride gas or phosphorus oxychloride gas. The halogenated phosphorus gas may be, for example, POF ３ Gas, POCl ３ Gas, POF ２ Cl ２ Gas, POFC1 ２ Gas or POF ２ It may be Cl gas.

[0074] In one embodiment, the first process gas may include a hydrogen-containing gas other than the deposition gas. The hydrogen-containing gas other than the deposition gas may include H ２ Gas and NH ３ The hydrogen-containing gas can contribute to improving the quality and increasing the thickness of the first protective film formed on the surface of the mask MK.

[0075] In step ST12, plasma is generated from the first process gas in the chamber 10. For example, 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. When a high-frequency electric field is generated between the shower head 13 and the substrate support 11, plasma is generated from the first process gas in the chamber 10. As a result, a first protective film is formed on the surface of the mask MK. During plasma generation, a bias signal may be supplied to the lower electrode of the substrate support 11. In this case, a bias potential is generated between the plasma and the substrate W, and ions in the plasma are attracted to the substrate W. The bias signal may be a bias DC signal supplied from the first DC generator 32a or a bias RF signal supplied from the second RF generator 31b. In one embodiment, a bias signal may not be supplied to the lower electrode of the substrate support 11.

[0076] 6 is a diagram showing an example of a first protective film PF formed on the surface of the mask MK. In one embodiment, the first protective film PF may be formed on a part or all of the surface of the mask MK. For example, the first protective film PF may be formed on a part or all of the sidewall SS of the mask MK. Also, for example, the first protective film PF may be formed on a part or all of the top surface TP of the mask MK. In the example shown in FIG. 6, the first protective film PF is formed on the sidewall SS of the mask MK to surround the opening OP and is also formed across the top surface TP of the mask MK. In one embodiment, the first protective film PF does not need to be formed on the bottom of the opening OP. That is, the first protective film PF may be formed on the surface of the mask MK so that the silicon-containing film SF is exposed at the bottom of the opening OP.

[0077] The first protective film PF is a film containing an element derived from a deposition gas (e.g., carbon, silicon, or phosphorus) or a compound containing such an element, and provides protection for the mask MK during the etching process in step ST13.

[0078] (Step ST13: Etching) In step ST13, the silicon-containing film SF is etched using plasma generated from the second process gas. Step ST13 includes supplying the second process gas to the chamber 10 and generating plasma from the second process gas.

[0079] In one embodiment, during the treatment in step ST13, the temperature of the substrate support 11 or the substrate W may be controlled to the above-mentioned first temperature or second temperature, or may be controlled to a third temperature different from the first temperature and the second temperature. In one embodiment, the third temperature is 0°C or less, 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.

[0080] In one embodiment, during the process in step ST13, the pressure in the chamber 10 may be controlled to the first pressure or a second pressure different from the first pressure. The second pressure may be 30 mTorr or less, 20 mTorr or less, or 15 mTorr or less. The second pressure may be 1 mTorr or more.

[0081] In step ST13, a second process gas is supplied into the chamber 10. The second process gas may be supplied into the chamber 10 from the gas supply unit 20 via the gas inlet 13c of the shower head 13, for example.

[0082] In one embodiment, the second process gas includes hydrogen fluoride (HF) gas. The HF gas may have the highest flow rate (partial pressure) of any of the second process gases, excluding the inert gas. In one example, the flow rate of the HF gas may be 50 vol.% or more, 60 vol.% or more, 70 vol.% or more, 80 vol.% or more, 90 vol.% or more, or 95 vol.% or more of the total flow rate of the second process gas (if the second process gas includes an inert gas, the flow rate of all gases excluding the inert gas). The flow rate of the HF gas may be less than 100 vol.%, 99.5 vol.% or less, 98 vol.% or less, or 96 vol.% or less of the total flow rate of the second process gas. In one example, the flow rate of the HF gas is 70 vol.% or more and 96 vol.% or less of the total flow rate of the second process gas.

[0083] In one embodiment, the second process gas may include a gas capable of generating hydrogen fluoride species (HF species) in plasma, instead of a part or all of the HF gas. The HF species include at least one of hydrogen fluoride gas, radicals, and ions.

[0084] The gas capable of generating HF species may be, for example, a hydrofluorocarbon gas. The hydrofluorocarbon gas may have two or more carbon atoms, three or more carbon atoms, or four or more carbon atoms. In one example, the hydrofluorocarbon gas is CH ２ F ２ Gas, C ３ H ２ F ４ Gas, C ３ H ２ F ６ Gas, C ３ H ３ F ５ Gas, C ４ H ２ F ６ Gas, C ４ H ５ F ５ Gas, C ４ H ２ F８ Gas, C ５ H ２ F ６ Gas, C ５ H ２ F １０ Gas and C ５ H ３ F ７ The hydrofluorocarbon gas is at least one selected from the group consisting of CH ２ F ２ Gas, C ３ H ２ F ４ Gas, C ３ H ２ F ６ Gas and C ４ H ２ F ６ The gas is at least one selected from the group consisting of:

[0085] The gas capable of generating HF species may be, for example, a mixed gas containing a hydrogen source and a fluorine source. ２ Gas, NH ３ Gas, H ２ O gas, H ２ O ２ Gas and hydrocarbon gas (CH ４ Gas, C ３ H ６ The fluorine source may be at least one selected from the group consisting of NF ３ Gas, SF ６ Gas, WF ６ gas or XeF ２ The fluorine source may be a fluorine-containing gas that does not contain carbon, such as a fluorocarbon gas or a hydrofluorocarbon gas. The fluorine source may also be a fluorine-containing gas that contains carbon, such as a fluorocarbon gas or a hydrofluorocarbon gas. An example of a fluorocarbon gas is CF ４ Gas, C ２ F ２ Gas, C ２ F ４ Gas, C ３ F ６ Gas, C ３ F ８ Gas, C ４ F ６ Gas, C ４ F８ Gas and C ５ F ８ The hydrofluorocarbon gas may be at least one selected from the group consisting of CHF ３ Gas, CH ２ F ２ Gas, CH ３ F gas, C ２ HF ５ Gas and hydrofluorocarbon gas containing three or more C (C ３ H ２ F ４ Gas, C ３ H ２ F ６ Gas, C ４ H ２ F ６ The gas may be at least one selected from the group consisting of:

[0086] In one embodiment, the second process gas may include a nitrogen-containing gas. ２ Gas, NF ３ Gas, NH ３ gas, NO gas and NO ２ When the second process gas contains a nitrogen-containing gas, a protective film (hereinafter also referred to as a "second protective film") can be formed on the sidewall of the silicon-containing film SF formed by etching. The second protective film can suppress a phenomenon in which the silicon-containing film SF or the like is etched in the horizontal direction (hereinafter also referred to as "bowing") in step ST13.

[0087] As the nitrogen-containing gas, N ２ A gas that does not contain fluorine atoms or has a relatively low ratio of F atoms to N atoms, such as a gas, may be used. In this case, etching of the mask MK and the first protective film formed on the surface of the mask MK is suppressed in step ST13, so that blocking of the opening OP can be further suppressed.

[0088] The second process gas may include multiple nitrogen-containing gases. For example, the second process gas may include a first nitrogen-containing gas and a second nitrogen-containing gas. The first nitrogen-containing gas and the second nitrogen-containing gas may have different ratios of fluorine atoms to nitrogen atoms. In one example, the second nitrogen-containing gas may contain no fluorine atoms or may have a lower ratio of fluorine atoms to nitrogen atoms than the first nitrogen-containing gas. For example, the first nitrogen-containing gas may be NF gas, and the second nitrogen-containing gas may be N gas. In one embodiment, when the second process gas includes a first nitrogen-containing gas and a second nitrogen-containing gas, the ratio of the first nitrogen-containing gas to the second nitrogen-containing gas may be changed continuously or stepwise depending on the depth of the recess formed in the silicon-containing film SF, the process time (the elapsed time since the start of step ST12), and the like. In another embodiment, a period in which the second process gas includes the first nitrogen-containing gas and a period in which the second process gas includes the second nitrogen-containing gas may be repeated.

[0089] In one embodiment, the second process gas may further include a phosphorus-containing gas. The phosphorus-containing gas may be, for example, a halogenated phosphorus gas. The halogenated phosphorus gas may be PF5. ３ Gas, PF ５ Gas, PCl ３ Gas, PCl ５ Gas, PClF ２ Gas, PCl ２ F gas and PCl ２ F ３ In one example, the halogenated phosphorus gas may be at least one selected from the group consisting of PF ３ Gas, PF ５ Gas or PCl ３ It's gas.

[0090] In one embodiment, the second process gas may further comprise a metal-containing gas. The metal-containing gas may comprise at least one metal selected from the group consisting of tungsten, titanium, ruthenium, and molybdenum. In one embodiment, the metal-containing gas may further comprise a halogen. The metal-containing gas may be WF ２ Gas, WF ４ Gas, WF ５ Gas, WF６ Gas, WCl ２ Gas, WCl ４ Gas, WCl ５ Gas, WCl ６ Gas, MoF ４ Gas, MoF ６ Gas, MoCl ６ Gas, TiCl ４ In one embodiment, the flow rate of the metal-containing gas may be 5% by volume or less of the total flow rate of the second process gas.

[0091] In one embodiment, the second process gas may further include a halogen-containing gas other than fluorine. The halogen-containing gas other than fluorine may be, for example, a chlorine-containing gas, a bromine-containing gas, and / or an iodine-containing gas. In one example, the chlorine-containing gas may be Cl. ２ , SiCl ２ , SiCl ４ , CCl ４ , SiH ２ Cl ２ , Si ２ Cl ６ , CHCl ３ , S.O. ２ Cl ２ , BCl ３ , PCl ３ , PCl ５ and POCl ３ The bromine-containing gas is at least one gas selected from the group consisting of Br ２ , HBr, CBr ２ F ２ , C ２ F ５ Br, PBr ３ , PBr ５ , POBr ３ and BBr ３ The iodine-containing gas is at least one gas selected from the group consisting of HI, CF, and the like. ３ I, C ２ F ５ I, C ３ F ７ I, IF ５ , IF ７ , I ２ , P.I. ３In one example, the halogen-containing gas other than fluorine is at least one gas selected from the group consisting of Cl ２ Gas, Br ２ In one example, the halogen-containing gas other than fluorine may be at least one selected from the group consisting of Cl gas and HBr gas. ２ gas or HBr gas.

[0092] In one embodiment, the second process gas may further include an oxygen-containing gas, such as O ２ , CO, CO ２ , H ２ O and H ２ O ２ In one example, the oxygen-containing gas may be at least one gas selected from the group consisting of H ２ Oxygen-containing gases other than O, e.g., O ２ , CO, CO ２ and H ２ O ２ The flow rate of the oxygen-containing gas may be adjusted depending on the flow rate of other gases (e.g., carbon-containing gas) contained in the second process gas.

[0093] In one embodiment, the second process gas is NF ３ Gas, SF ６ Gas, WF ６ gas or XeF ２ It may further include a carbon-free fluorine-containing gas such as molybdenum.

[0094] In one embodiment, the second process gas may further include an inert gas, such as a noble gas such as Ar gas, He gas, or Kr gas, or N ２ Gas is fine.

[0095] In step ST13, plasma is generated from the second process gas in the chamber 10. For example, 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. When a high-frequency electric field is generated between the shower head 13 and the substrate support 11, plasma is generated from the etching gas in the chamber 10. Active species such as ions and radicals in the plasma etch the silicon-containing film SF exposed through the opening OP in the mask MK. During plasma generation, a bias signal may be supplied to the lower electrode of the substrate support 11. In this case, a bias potential is generated between the plasma and the substrate W, which may attract ions in the plasma to the substrate W and promote etching. The bias signal may be a bias DC signal supplied from the DC generator 32a or a bias RF signal supplied from the second RF generator 31b. In one embodiment, a bias signal may not be supplied to the lower electrode of the substrate support 11.

[0096] In one embodiment, the first layer containing silicon and oxygen and the second layer containing silicon and nitrogen of the silicon-containing film SF may be etched under the same etching conditions or different etching conditions, including one or more of the temperatures of the substrate support 11 and the substrate W, the pressure in the chamber 10, the power of the source RF signal and the bias signal, and the flow rate and type of the second process gas.

[0097] For example, the second process gas may include a first etching gas and a second etching gas different from the first etching gas. In this case, the first layer is etched by plasma generated from the first etching gas, and the second layer is etched by plasma generated from the second etching gas. Either the first etching gas or the second etching gas may contain hydrogen fluoride gas, or both may contain hydrogen fluoride gas. When both the first etching gas and the second etching gas contain hydrogen fluoride gas, the flow rate ratio of the hydrogen fluoride gas in the first etching gas may be different from the flow rate ratio of the hydrogen fluoride gas in the second etching gas. Furthermore, when both the first etching gas and the second etching gas contain hydrogen fluoride gas, the gas other than hydrogen fluoride gas contained in the first etching gas may be different from the gas other than hydrogen fluoride gas contained in the second etching gas.

[0098] 7 is a diagram illustrating an example of a substrate W during etching. As shown in Fig. 7, the portion of the silicon-containing film SF exposed at the opening OP is etched in the depth direction (from top to bottom in Fig. 7) by activated species in the plasma. This forms a recess RC having a shape corresponding to the opening OP.

[0099] In the etching of step ST13, the protective film PF provides protection for the surface (sidewall SS and / or top surface TP) of the mask MK on which the protective film PF is formed. That is, the protective film PF suppresses etching of the surface of the mask MK by activated species in the plasma. Since etching of the mask MK is suppressed, reaction products derived from the mask MK are reduced, and the reaction products are also suppressed from re-adhering to the mask MK. This can suppress blocking of the openings in the mask MK. Furthermore, since etching of the mask MK is suppressed, the etching selectivity of the silicon-containing film SF relative to the mask MK can be improved.

[0100] The etching in step ST13 is stopped when a given stop condition is satisfied, which may be set appropriately based on the etching time, the depth of the recess RC, etc.

[0101] <Modification> FIGS. 8A to 8C are flowcharts illustrating another example of the method MT. As shown in FIG. 8A, in the method MT, steps ST12 and ST13 may be performed simultaneously. That is, a process gas containing a first process gas and a second process gas may be simultaneously supplied into the chamber 10, and plasma may be generated from the process gases. In this case, the formation of the protective film PF and the etching of the silicon-containing film SF proceed in parallel. At this time, the flow rate of HF gas in the process gas may be greater than the flow rate of a deposition gas (e.g., a carbon-containing gas, a phosphorus-containing gas, or a silicon-containing gas). Furthermore, when the first process gas contains a hydrogen-containing gas other than the deposition gas, the flow rate of the hydrogen-containing gas in the process gas may be approximately the same as the flow rate of HF gas. For example, the ratio of the flow rate of the hydrogen-containing gas to the flow rate of the HF gas may be 0.4 to 1.5, 0.5 to 1.4, or 0.8 to 1.2. In one example, the flow rate of the hydrogen-containing gas in the process gas is approximately the same as the flow rate of the HF gas.

[0102] In the method MT, the order and number of steps ST12 and ST13 may be set as appropriate. For example, as shown in FIG. 8B , the silicon-containing film SF may first be etched to a certain extent (step ST13), then a protective film may be formed on the surface of the mask MK (step ST12), and then etching may be performed again (step ST13). Furthermore, as shown in FIG. 8C , steps ST12 and ST13 may form a single cycle, which may be repeated multiple times until a stop condition is met (step ST14: YES). That is, the formation of the protective film PF on the surface of the mask MK and the etching of the silicon-containing film SF may be alternately repeated. Note that, as in the examples of FIGS. 8A to 8C , when step ST12 is performed with the recess RC formed in the silicon-containing film SF, the protective film PF may be formed as follows. For example, the protective film PF may be formed on the surface of the mask MK as well as on part or all of the sidewalls of the silicon-containing film SF surrounding the recess RC. Furthermore, for example, the protective film PF may be formed only on the surface of the mask MK, and may not be formed on the sidewall of the silicon-containing film SF surrounding the recess RC.

[0103] 8D is a flowchart illustrating an example of steps ST12 and ST13 in FIG. 8A . In this example, as described above, steps ST12 and ST13 are simultaneously performed in the method MT. That is, a process gas containing a first process gas and a second process gas is simultaneously supplied into the chamber 10, and plasma is generated from the process gas. The supply of the second process gas into the chamber 10 may include a first period (step STa) containing a nitrogen-containing gas at a first flow rate and a second period (step STb) containing no nitrogen-containing gas or a nitrogen-containing gas at a second flow rate lower than the first flow rate. As shown in FIG. 8E , the first period and the second period constitute one cycle, and the cycle may be repeated multiple times until a stop condition is satisfied (step STc: YES).

[0104] When the second process gas contains a nitrogen-containing gas, a first protective film is formed on the sidewalls of the mask MK, and a second protective film may be formed on the sidewalls of the silicon-containing film SF formed by etching. Depending on the etching conditions, a second protective film may also be formed on the bottom surface of the silicon-containing film SF, which may reduce the etching rate of the silicon-containing film SF. In contrast, in this example, the first process gas in the second period does not contain a nitrogen-containing gas or contains a nitrogen-containing gas at a flow rate lower than that in step STa, so the formation of the second protective film in this period is suppressed. As a result, the reduction in the etching rate of the silicon-containing film SF due to the second protective film can be suppressed.

[0105] FIG. 9 is a diagram showing another example of a substrate W (hereinafter referred to as "substrate W1"). As shown in FIG. 9, the silicon-containing film SF of the substrate W1 includes a first region RE1 and a second region RE2 on the first region. The first region RE1 is a stacked film in which first layers SF1 and second layers SF2 are alternately stacked. The second region RE2 is a film including a third layer SF3. The first layer SF1 is a film containing silicon and oxygen, such as a silicon oxide film. The second layer SF2 is a film containing silicon and nitrogen, such as a silicon nitride film. The third layer SF3 may be a silicon-containing film different from the first layer SF1. The third layer SF3 may be the same silicon-containing film as the second layer SF2, or may be a different silicon-containing film. The second layer SF3 may be a film containing silicon and nitrogen, such as a silicon nitride film or a silicon carbonitride film. The first layer SF1 may be thicker than the second layer SF2. The third layer SF3 may be thicker than the second layer SF2. <Examples> The present disclosure is not limited in any way by the following examples and reference examples.

[0106] In Example 1, a substrate having a structure similar to that of the substrate W1 shown in FIG. 9 was etched using the plasma processing apparatus 1 described in FIG. 2 according to the flowchart described in FIG. 8A. A WSiN film having a hole pattern with an opening dimension of 20 nm was used as the mask MK. The processing gas was CH ４ The first process gas contained HF gas, and the second process gas contained CH ４ The flow rate of the gas was 60% of the flow rate of the HF gas. The pressure in the chamber 10 was set to 30 mTorr or less. Etching was performed for 450 seconds.

[0107] Example 2 In Example 2, the processing gas was CH 4 as the first processing gas. ４ The first process gas contained HF gas, and the second process gas contained CH ４ The flow rate of the gas was 40% of the flow rate of the HF gas. Other points were the same as in Example 1.

[0108] Example 3 In Example 3, the processing gas was CH 4 as the first processing gas. ４ Gas and H ２The first process gas contained HF gas, and the second process gas contained CH ４ The flow rate of the gas is 40% of the flow rate of the HF gas. ２ The flow rate of the gas was the same as that of the HF gas.

[0109] Example 4 In Example 4, the processing gas was CH 4 as the first processing gas. ４ Gas and H ２ The first process gas contained HF gas, and the second process gas contained CH ４ The flow rate of the gas is 20% of the flow rate of the HF gas. ２ The flow rate of the gas was twice that of the HF gas, and the other points were the same as in Example 1.

[0110] In all of Examples 1 to 4, the etching reached the underlayer UF, and no etching stop occurred. That is, in all of Examples 1 to 4, the blocking of the openings in the mask MK was suppressed. In Examples 1, 3, and 4, almost no deposits originating from the mask MK were observed on the sidewalls of the mask MK at the end of etching. In Example 2, deposits originating from the mask MK were observed on part of the sidewalls of the mask MK. From Examples 1 to 4, it can be seen that the CH ４ When the gas flow rate ratio is reduced, the deposits originating from the mask MK increase. This increase in deposits is due to the presence of H ２ It is clear that this can be suppressed by adding gas.

[0111] Example 5 In Example 5, the processing gas was CH 4 as the first processing gas. ４ Gas and H ２ The first process gas contained HF gas and NF3 gas. ４ The flow rate of the gas is 40% of the flow rate of the HF gas. ２ The flow rate of the gas was the same as that of the HF gas.

[0112] Example 6 In Example 6, the processing gas was CH 4 as the first processing gas. ４ Gas and H ２ gas, and the second process gas includes HF gas and NF ３It contained gas. ４ The flow rate of the gas is 40% of the flow rate of the HF gas. ２ In Example 6, the process ST12 and the process ST13 included a first period and a second period, as shown in FIGS. 8D and 8E. In the first period, the second process gas was NF. ３ In the second period, the second process gas included NF ３ In other respects, the present invention was the same as that of Example 1.

[0113] In Examples 5 and 6, etching also reached the underlayer UF, and no etching stop occurred. That is, blocking of the openings in the mask MK was also suppressed in Examples 5 and 6. Furthermore, bowing of the silicon-containing film SF was suppressed in Examples 5 and 6 compared to Examples 1 to 4. In these Examples, a second protective film was observed in the silicon-containing film SF. The second protective film contained ammonium silicofluoride. In Example 6, a decrease in the etching rate of the silicon-containing film SF was suppressed compared to Example 5. This is thought to be because the formation of the second protective film on the bottom surface of the silicon-containing film SF during the second period was suppressed.

[0114] Embodiments of the present disclosure further include the following aspects.

[0115] (Supplementary Note 1) An etching method comprising: (a) providing a substrate into a chamber, the substrate including a first film and a second film defining an opening on the first film, the first film being a laminated film including a first layer including silicon and oxygen and a second layer including silicon and nitrogen, and the second film including a metal-containing film or a carbon-containing film; (b) forming a protective film on a surface of the second film by plasma generated from a first process gas including a deposition gas, the pressure in the chamber being controlled to 30 mTorr or less; and (c) etching the first film through the second film on which the protective film has been formed by plasma generated from a second process gas including hydrogen fluoride gas.

[0116] (Supplementary Note 2) The etching method according to Supplementary Note 1, wherein the first film includes a first region in which the first layer and the second layer are alternately stacked, and a second region on the first region, the second region includes a third layer containing silicon and nitrogen, and the first layer is thicker than the second layer, and the third layer is thicker than the second layer.

[0117] (Supplementary Note 3) The etching method according to Supplementary Note 1 or Supplementary Note 2, wherein the second film contains at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium.

[0118] (Supplementary Note 4) The etching method according to Supplementary Note 3, wherein the second film contains the metal and at least one element selected from the group consisting of silicon, carbon, nitrogen, oxygen, boron, hydrogen, and phosphorus.

[0119] (Supplementary Note 5) The etching method according to any one of Supplementary Note 1 to Supplementary Note 4, wherein the opening has an opening dimension of 50 nm or less.

[0120] (Supplementary Note 6) The etching method according to any one of Supplementary Note 1 to Supplementary Note 5, wherein (b) and (c) are carried out simultaneously.

[0121] (Supplementary Note 7) The etching method according to any one of Supplementary Note 1 to Supplementary Note 6, wherein a flow rate of the hydrogen fluoride gas in the second process gas is higher than a flow rate of the deposition gas in the first process gas.

[0122] (Supplementary Note 8) The etching method according to any one of Supplementary Note 1 to Supplementary Note 7, wherein a cycle including (b) and (c) is repeated.

[0123] (Supplementary Note 9) The etching method according to any one of Supplementary Notes 1 to 8, wherein in (a), the substrate is placed on a substrate support in the chamber, and in (b) and (c), the temperature of the substrate or the substrate support is controlled to 0°C or below.

[0124] (Supplementary Note 10) The etching method according to any one of Supplementary Note 1 to Supplementary Note 9, wherein the deposition gas contains at least one gas selected from the group consisting of a carbon-containing gas, a silicon-containing gas, and a phosphorus-containing gas.

[0125] (Supplementary Note 11) The etching method according to Supplementary Note 10, wherein the first process gas further contains a hydrogen-containing gas other than the deposition gas.

[0126] (Supplementary Note 12) The etching method according to any one of Supplementary Note 1 to Supplementary Note 11, wherein the second process gas further contains a nitrogen-containing gas.

[0127] (Supplementary Note 13) The nitrogen-containing gas is N ２ Gas, NF ３ Gas, NH ３ gas, NO gas and NO ２ 13. The etching method of claim 12, further comprising at least one selected from the group consisting of:

[0128] (Supplementary Note 14) The etching method according to Supplementary Note 6, wherein (c) includes: (c1) a period in which plasma is generated from the second process gas further containing a nitrogen-containing gas at a first flow rate; and (c2) a period in which plasma is generated from the second process gas that does not contain a nitrogen-containing gas or further contains a nitrogen-containing gas at a second flow rate that is lower than the first flow rate.

[0129] (Supplementary Note 15) The etching method according to any one of Supplementary Note 1 to Supplementary Note 14, wherein the second process gas further contains a phosphorus-containing gas.

[0130] (Supplementary Note 16) The etching method according to any one of Supplementary Note 1 to Supplementary Note 15, wherein the second process gas further contains at least one gas selected from the group consisting of a metal-containing gas, a fluorine-containing gas not containing carbon, a halogen-containing gas other than fluorine, an oxygen-containing gas, and a boron-containing gas.

[0131] (Supplementary Note 17) The etching method according to any one of Supplementary Notes 1 to 16, wherein in (c), the etching of the second layer is carried out under the same conditions as the etching of the first layer.

[0132] (Supplementary Note 18) The etching method according to any one of Supplementary Notes 1 to 16, wherein in (c), the etching of the second layer is performed under conditions different from those for the etching of the first layer.

[0133] (Supplementary Note 19) The etching method according to Supplementary Note 18, wherein in (c), a first etching gas and a second etching gas different from the first etching gas are used as the second processing gas, and (c) includes: (c1) a step of etching the first layer with plasma generated from the first etching gas; and (c2) a step of etching the second layer with plasma generated from the second etching gas.

[0134] (Supplementary Note 20) (a) providing a substrate into a chamber, the substrate including a first film and a metal-containing mask on the first film, the first film including a first layer including a first silicon-containing film, a second layer including a second silicon-containing film different from the first silicon-containing film, and a third layer including a third silicon-containing film different from the first silicon-containing film and the second silicon-containing film, the third layer being disposed above the first layer and the second layer and having a thickness different from that of the first layer, the metal-containing mask including an opening pattern with an opening dimension of 50 nm or less; (b) forming a protective film on a surface of the metal-containing mask by plasma generated from a first process gas including a deposition gas, the pressure in the chamber being controlled to 30 mTorr or less; (c) etching the first film through the metal-containing mask on which the protective film is formed, by plasma generated from a second process gas, wherein the second process gas contains one or more types of gases capable of generating hydrogen fluoride in the plasma.

[0135] (Supplementary Note 21) The etching method according to Supplementary Note 20, wherein the first film includes a stacked film in which the first layer and the second layer are alternately stacked.

[0136] (Supplementary Note 22) The etching method according to Supplementary Note 20 or Supplementary Note 21, wherein the first layer is a silicon oxide film, the second layer is a silicon nitride film, and the third layer is a silicon carbonitride film.

[0137] (Supplementary Note 23) A plasma processing system comprising: a plasma processing apparatus having a chamber; and a controller, wherein the controller is configured to perform the following: (a) controlling a substrate to be provided into the chamber, the substrate including a first film and a second film defining an opening on the first film, the first film being a stacked film including a first layer containing silicon and oxygen and a second layer containing silicon and nitrogen, and the second film including a metal-containing film or a carbon-containing film; (b) controlling a protective film to be formed on a surface of the second film by plasma generated from a first process gas including a deposition gas, the control comprising controlling a pressure in the chamber to 30 mTorr or less; and (c) controlling a plasma to be generated from a second process gas including hydrogen fluoride gas, the first film being etched through the second film on which the protective film has been formed.

[0138] (Supplementary Note 24) A program causing a computer of a plasma processing system including a plasma processing apparatus having a chamber and a control unit to execute the following: (a) control of providing a substrate into the chamber, the substrate including a first film and a second film defining an opening on the first film, the first film being a laminated film including a first layer including silicon and oxygen and a second layer including silicon and nitrogen, and the second film including a metal-containing film or a carbon-containing film; (b) control of forming a protective film on a surface of the second film by plasma generated from a first processing gas including a deposition gas, the control controlling the pressure in the chamber to 30 mTorr or less; and (c) control of etching the first film through the second film on which the protective film has been formed by plasma generated from a second processing gas including hydrogen fluoride gas.

[0139] (Supplementary Note 25) A storage medium storing the program according to Supplementary Note 24.

[0140] The above embodiments are described for the purpose of explanation and are not intended to limit the scope of the present disclosure. Various modifications can be made to the above embodiments without departing from the scope and spirit of the present disclosure. For example, some components in one embodiment can be added to other embodiments. Also, some components in one embodiment can be replaced with corresponding components in other embodiments.

[0141] REFERENCE SIGNS LIST 1: plasma processing apparatus, 2: control unit, 10: plasma processing chamber, 10s: plasma processing space, 11: substrate support unit, 13: shower head, 20: gas supply unit, 31a: first RF generating unit, 31b: second RF generating unit, 32a: first DC generating unit, SF: silicon-containing film, MK: mask, OP: opening, PF: first protective film, RC: recess, UF: base film, W: substrate

Claims

1. (a) A step of providing a substrate in a chamber, wherein the substrate includes a first film and a second film defining an opening on the first film, the first film being a laminated film including a first layer containing silicon and oxygen and a second layer containing silicon and nitrogen, and the second film including a metal-containing film or a carbon-containing film; (b) A step of forming a protective film on the surface of the second film by plasma generated from a first processing gas containing a deposition gas, wherein the pressure in the chamber is controlled to 30 mTorr or less; (c) A step of etching the first film through the second film on which the protective film is formed by plasma generated from a second processing gas containing hydrogen fluoride gas. An etching method comprising the above steps.

2. The first film includes a first region in which the first layer and the second layer are alternately laminated, and a second region on the first region, the second region including a third layer containing silicon and nitrogen. The first layer is thicker than the second layer, and the third layer is thicker than the second layer. The etching method according to claim 1.

3. The second film includes at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, and titanium. The etching method according to claim 1.

4. The second film includes the metal and at least one element selected from the group consisting of silicon, carbon, nitrogen, oxygen, boron, hydrogen, and phosphorus. The etching method according to claim 3.

5. The opening dimension of the opening is 50 nm or less. The etching method according to claim 1.

6. The steps (b) and (c) are performed simultaneously. The etching method according to any one of claims 1 to 5.

7. The flow rate of the hydrogen fluoride gas in the second processing gas is higher than the flow rate of the deposition gas in the first processing gas. The etching method according to claim 6.

8. A cycle including the steps (b) and (c) is repeated. The etching method according to any one of claims 1 to 5.

9. In step (a), the substrate is disposed on a substrate support in the chamber. In steps (b) and (c), the temperature of the substrate or the substrate support is controlled to 0°C or less. The etching method according to any one of claims 1 to 5.

10. The etching method according to any one of claims 1 to 5, wherein the deposition gas contains at least one gas selected from the group consisting of a carbon-containing gas, a silicon-containing gas, and a phosphorus-containing gas.

11. The etching method according to claim 1, wherein the first processing gas further contains a hydrogen-containing gas other than the deposition gas.

12. The etching method according to any one of claims 1 to 5, wherein the second processing gas further contains a nitrogen-containing gas.

13. The nitrogen-containing gas is N ２ gas, NF ３ gas, NH ３ gas, NO gas, and NO ２ The etching method according to claim 12, comprising at least one selected from the group consisting of gas.

14. In (c), the period of generating plasma from the second processing gas further containing a nitrogen-containing gas at a first flow rate, and the period of generating plasma from the second processing gas further containing a nitrogen-containing gas at a second flow rate that does not contain a nitrogen-containing gas or is less than the first flow rate, the etching method according to claim 6.

15. The etching method according to any one of claims 1 to 5, wherein the second processing gas further contains a phosphorus-containing gas.

16. The etching method according to any one of claims 1 to 5, wherein the second processing gas further contains at least one gas selected from the group consisting of a metal-containing gas, a fluorine-containing gas not containing carbon, a halogen-containing gas other than fluorine, an oxygen-containing gas, and a boron-containing gas.

17. The etching method according to any one of claims 1 to 5, wherein in (c), the etching of the second layer is performed under the same conditions as the etching of the first layer.

18. The etching method according to any one of claims 1 to 5, wherein in (c), the etching of the second layer is performed under conditions different from those of the etching of the first layer.

19. In (c), as the second processing gas, a first etching gas and a second etching gas different from the first etching gas are used. (c) includes: (c1) a step of etching the first layer with plasma generated from the first etching gas; and (c2) a step of etching the second layer with plasma generated from the second etching gas. The etching method according to claim 18.

20. (a) A step of providing a substrate in a chamber, wherein the substrate includes a first film and a metal-containing mask on the first film, the first film includes a first layer including a first silicon-containing film, a second layer including a second silicon-containing film different from the first silicon-containing film, and a third layer including a third silicon-containing film different from the first silicon-containing film and the second silicon-containing film, the third layer is disposed above the first layer and the second layer and has a different thickness from the first layer, and the metal-containing mask includes an opening pattern having an opening dimension of 50 nm or less; (b) A step of forming a protective film on the surface of the metal-containing mask by plasma generated from a first processing gas containing a deposition gas, wherein the pressure in the chamber is controlled to 30 mTorr or less; (c) A step of etching the first film through the metal-containing mask on which the protective film is formed by plasma generated from a second processing gas, wherein the second processing gas includes one or more gases capable of generating hydrogen fluoride in the plasma. An etching method comprising the above steps.

21. The etching method according to claim 20, wherein the first film includes a laminated film in which the first layer and the second layer are alternately laminated.

22. The etching method according to claim 20 or claim 21, wherein the first layer is a silicon oxide film, the second layer is a silicon nitride film, and the third layer is a silicon carbonitride film.

23. A plasma processing system including a plasma processing apparatus including a chamber and a control unit, wherein the control unit is configured to: (a) Control to provide a substrate in the chamber, wherein the substrate includes a first film and a second film defining an opening on the first film, the first film is a laminated film including a first layer containing silicon and oxygen and a second layer containing silicon and nitrogen, and the second film includes a metal-containing film or a carbon-containing film; (b) Control to form a protective film on the surface of the second film by plasma generated from a first processing gas containing a deposition gas, and control the pressure in the chamber to 30 mTorr or less; (c) Control to etch the first film through the second film on which the protective film is formed by plasma generated from a second processing gas containing hydrogen fluoride gas.

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