Etching method and plasma treatment device

Abstract

An etching method including: (a) a step for preparing a substrate on a substrate support part, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, and the mask comprises a side wall defining at least one opening for exposing the silicon-containing film; and (b) a step for generating plasma from a treatment gas which includes a hydrogen fluoride gas and a bromine-containing gas, the step including forming a first protective film, which includes bromine, to a lower part of the side wall, and forming a recess in the silicon-containing film.

Description

Etching method and plasma processing apparatus

[0001] Exemplary embodiments of this disclosure relate to etching methods and plasma processing apparatus.

[0002] Patent Document 1 discloses a method for etching a film within a substrate. The film contains silicon, and the substrate further has a mask provided on the film. The mask contains amorphous carbon or an organic polymer. The etching in this method uses plasma generated from a processing gas containing hydrocarbon gas and fluorohydrocarbon gas.

[0003] Japanese Patent Publication No. 2016-39310

[0004] This disclosure provides a technology for suppressing shape abnormalities during etching.

[0005] In one exemplary embodiment of the present disclosure, an etching method is provided, comprising: (a) a step of preparing a substrate on a substrate support, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, the mask comprising a side wall defining at least one opening that exposes the silicon-containing film; and (b) a step of generating a plasma from a processing gas comprising a hydrogen fluoride gas and a bromine-containing gas, comprising forming a first protective film containing bromine up to the bottom of the side wall and forming a recess in the silicon-containing film.

[0006] According to one exemplary embodiment of the present disclosure, a technique for suppressing shape abnormalities in etching can be provided.

[0007] This is a diagram illustrating an example configuration of a plasma processing system. This is a diagram illustrating an example configuration of a capacitively coupled plasma processing apparatus. This is a flowchart illustrating an example of this etching method. This is a diagram illustrating an example of the cross-sectional structure of the substrate W prepared in step ST1. This is a diagram illustrating an example of the cross-sectional structure of the substrate W during step ST2.

[0008] The embodiments of this disclosure are described below.

[0009] In one exemplary embodiment, (a) a step of preparing a substrate on a substrate support, wherein the substrate includes a silicon-containing film and a mask on the silicon-containing film, and the mask includes sidewalls defining at least one opening exposing the silicon-containing film; and (b) a step of generating plasma from a processing gas including hydrogen fluoride gas and bromine-containing gas, including forming a first protective film containing bromine up to the lower part of the sidewalls and forming recesses in the silicon-containing film. An etching method is provided that includes these steps.

[0010] In one exemplary embodiment, the lower part of the sidewalls includes a boundary with the silicon-containing film.

[0011] In one exemplary embodiment, the bromine-containing gas includes a bromine-containing unsaturated halon gas.

[0012] In one exemplary embodiment, the bromine-containing gas is R １ R ２ C═CR ３ R ４ (where R １ , R ２ , R ３ and R ４ each independently represent a hydrogen atom or a halogen atom, and at least one of R １ , R ２ , R ３ and R ４ is a bromine atom.) and includes an unsaturated halon represented thereby.

[0013] In one exemplary embodiment, the unsaturated halon includes C ２ BrF ３ .

[0014] In one exemplary embodiment, (b) further includes forming a second protective film on at least a part of the sidewalls defining the recesses.

[0015] In one exemplary embodiment, the second protective film does not contain bromine or contains a lower concentration of bromine than the first protective film.

[0016] In one exemplary embodiment, the etching method further includes (c) a step of controlling the temperature of the substrate support portion to 0°C or less between (a) and (b).

[0017] In one exemplary embodiment, the processing gas further comprises at least one gas selected from the group consisting of phosphorus-containing gases, carbon-containing gases, halogen-containing gases different from the bromine-containing unsaturated halon gases, and metal-containing gases.

[0018] In one exemplary embodiment, the phosphorus-containing gas is PF ３ and POCl ３ It includes at least one of the following.

[0019] In one exemplary embodiment, the carbon-containing gas includes at least one selected from the group consisting of CF-based gases, CHF-based gases, and CH-based gases.

[0020] In one exemplary embodiment, the halogen-containing gas is Cl ２ It includes at least one selected from the group consisting of HCl and HBr.

[0021] In one exemplary embodiment, the metal-containing gas is WF ６ and MoF ６ It includes at least one of the following.

[0022] In one exemplary embodiment, the silicon-containing film includes at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, and a polycrystalline silicon film.

[0023] In one exemplary embodiment, the mask includes at least one selected from the group consisting of carbon-containing films, metal-containing films, and other silicon-containing films.

[0024] In one exemplary embodiment, the metal-containing film includes a tungsten-containing film.

[0025] In one exemplary embodiment, the other silicon-containing film includes a BSi film.

[0026] In one exemplary embodiment, a plasma processing apparatus is provided, comprising a chamber, a substrate support provided within the chamber, and a control unit, wherein the control unit is configured to perform controls including: (a) a control for preparing a substrate on the substrate support unit, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, the mask having side walls that define at least one opening for exposing the silicon-containing film; and (b) a control for generating plasma from a processing gas containing hydrogen fluoride gas and bromine-containing gas, the control unit comprising forming a first protective film containing bromine up to the bottom of the side walls and forming a recess in the silicon-containing film.

[0027] Hereinafter, each embodiment of this disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are denoted by the same reference numeral, and redundant explanations are omitted. Unless otherwise specified, positional relationships such as top, bottom, 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 actual ratios are not limited to those shown.

[0028] <Example of a Plasma Processing System> Figure 1 is a diagram illustrating an example of the configuration 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 unit 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 outlet for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20, which will be described later, and the gas outlet is connected to an exhaust system 40, which will be described later. The substrate support unit 11 is located in the plasma processing space and has a substrate support surface for supporting a substrate.

[0029] The plasma generation 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 capacitively coupled plasma (CCP), inductively coupled plasma (ICP), ECR (Electron Cyclotron Resonance) plasma, helicon wave excited plasma (HWP), or surface wave plasma (SWP), etc. Various types of plasma generation units, including AC (Alternating Current) plasma generation units and DC (Direct Current) plasma generation units, may also be used. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0030] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various processes described herein. The control unit 2 may be configured to control the elements of the plasma processing apparatus 1 to perform the 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 is implemented, for example, by a computer 2a. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The functions realized by the processing unit 2a1 described herein may be implemented in a circuit or processing circuit, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), a conventional circuit, and / or a combination thereof, programmed to realize the described functions. The processor is considered to be a circuit or processing circuit, including transistors and other circuits. The processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be pre-stored in the storage unit 2a2 or retrieved via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 and executed by the processing unit 2a1. The medium may be various storage media readable by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The storage unit 2a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).In this disclosure, circuits, units, and means are hardware programmed to perform or configured to perform the functions described. Such hardware may be any hardware described in this disclosure, or any hardware known to be programmed to perform or execute the functions described. If such hardware is a processor that is considered to be a type of circuit, such circuit, means, or unit is a combination of hardware and software used to constitute such hardware and / or processor.

[0031] The following describes an example configuration of a capacitively coupled plasma processing apparatus as an example of a plasma processing apparatus 1. Figure 2 is a diagram illustrating an example configuration of a capacitively coupled plasma processing apparatus.

[0032] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply system 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas introduction unit includes a shower head 13. The substrate support unit 11 is located inside the plasma processing chamber 10. The shower head 13 is located 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 walls 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 housing of the plasma processing chamber 10.

[0033] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the 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 portion 111 surrounds the central region 111a of the main body portion 111 in a plan view. The substrate W is placed on the central region 111a of the main body portion 111, and the ring assembly 112 is placed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also called the substrate support surface for supporting the substrate W, and the annular region 111b is also called the ring support surface for supporting the ring assembly 112.

[0034] 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 placed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic chuck electrode 1111b placed within the ceramic member 1111a. The electrostatic chuck electrode 1111b is also called a clamping electrode. In one embodiment, the electrostatic chuck electrode 1111b is electrically connected or coupled to a chuck power supply. The chuck power supply may be a DC power supply or an AC power supply. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Furthermore, other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have an annular region 111b. In this case, the ring assembly 112 may be placed on the annular electrostatic chuck or the annular insulating member, or it may be placed on both the electrostatic chuck 1111 and the annular insulating member. In addition, at least one bias electrode, which is electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed inside the ceramic member 1111a. In this case, at least one bias electrode functions as a lower electrode. Also, the conductive member of the base 1110 and the bias electrode inside the ceramic member 1111a may function as multiple lower electrodes. In one embodiment, the first voltage generation unit 32a, which functions as a voltage pulse generation unit described later, is electrically connected or coupled to the bias electrode inside the ceramic member 1111a, and the first RF generation unit 31a, described later, is electrically connected or coupled to the conductive member of the base 1110. Furthermore, the electrostatic chuck electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0035] 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 covering ring. The edge rings are formed of a conductive or insulating material, and the covering rings are formed of an insulating material.

[0036] The substrate support section 11 may also include a temperature control 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 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 through the flow path 1110a. In one embodiment, the flow path 1110a is formed within the base 1110, and one or more heaters are arranged within the ceramic member 1111a of the electrostatic chuck 1111. The substrate support section 11 may also include a heat transfer gas supply section configured to supply heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0037] The showerhead 13 is configured to introduce at least one processing 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 a plurality of gas inlet ports 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s through the plurality of gas inlet ports 13c. The showerhead 13 also includes at least one upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the side wall 10a.

[0038] 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 to the shower head 13 from a corresponding gas source 21 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of at least one processing gas.

[0039] The power supply system 30 includes a power supply 31 that is electrically connected to or coupled to the plasma processing chamber 10. In one embodiment, the power supply 31 is electrically connected to or coupled to the plasma processing chamber 10 via at least one impedance matcher. The impedance matcher may be a mechanically controlled matcher or an electronically controlled matcher. The 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 plasma from at least one processing gas supplied to the plasma processing space 10s. Therefore, the power supply 31 can function as at least part of the plasma generation unit 12. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and ionic components in the formed plasma can be drawn into the substrate W.

[0040] The power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode and is configured to generate a source RF signal (source RF power) to generate plasma in the plasma processing space 10s. In one embodiment, the first RF generation unit 31a is electrically connected or coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matcher. 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 generation unit 31a may be configured to generate a plurality of source RF signals having different frequencies. One or more generated source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0041] The second RF generation unit 31b is electrically connected to or coupled to at least one lower electrode and is configured to generate a bias RF signal (bias RF power). In one embodiment, the second RF generation unit 31b is electrically connected to or coupled to at least one lower electrode via at least one impedance matcher. When the first RF generation unit 31a is electrically connected to or coupled to a lower electrode, the second RF generation unit 31b may be electrically connected to or coupled to the same lower electrode, or it may be electrically connected to or coupled to a different lower electrode. 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 generation unit 31b may 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 various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0042] The power supply system 30 may also include a power supply 32 that is electrically connected to or coupled to the plasma processing chamber 10. The power supply 32 includes a first voltage generation unit 32a and a second voltage generation unit 32b. In one embodiment, the first voltage generation unit 32a is electrically connected to or coupled to at least one lower electrode and is configured to generate a first voltage signal. The generated first voltage signal is applied to at least one lower electrode. In one embodiment, the second voltage generation unit 32b is electrically connected to or coupled to at least one upper electrode and is configured to generate a second voltage signal. The generated second voltage signal is applied to at least one upper electrode.

[0043] In various embodiments, the first and / or second voltage signals may be pulsed. In this case, the first voltage generation unit 32a and / or the second voltage generation unit 32b function as voltage pulse generation units configured to generate a sequence of voltage pulses. Thus, the sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. In one embodiment, the sequence of voltage pulses has a plurality of cycles, each cycle including a burst of voltage pulses in a first period and a constant reference voltage in a second period. That is, in the sequence of voltage pulses, the burst of voltage pulses is repeated. The absolute value of the voltage level of the voltage pulse is greater than the absolute value of the voltage level of the reference voltage. The voltage pulse may have an arbitrary waveform having a rectangle, trapezoid, triangle, or a combination thereof, and the arbitrary waveform may change over time. The voltage pulse may have positive polarity or negative polarity. The sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses within one cycle. The first and second voltage generation units 32a and 32b may be provided in addition to the power supply 31, and the first voltage generation unit 32a may be provided in place of the second RF generation unit 31b.

[0044] The exhaust system 40 may be connected to, for example, a gas outlet 10e located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure regulating valve regulates the pressure in the plasma processing space 10s. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

[0045] <Example of Etching Method> Figure 3 is a flowchart of an etching method (hereinafter also referred to as "this method") according to an exemplary embodiment. This method includes a step ST1 for preparing a substrate and a step ST2 for generating plasma. Each step may be performed using any one of the plasma processing systems described above (see Figures 1 to 2), or it may be performed using two or more of these plasma processing systems. For example, this method may be performed using the plasma processing system shown in Figure 1. In the following, the case in which the control unit 2 controls each part of the plasma processing apparatus 1 shown in Figure 2 to perform this method on the substrate W will be described as an example.

[0046] (Step ST1: Preparation of the substrate) In step ST1, the substrate W is prepared on the substrate support section 11. In one embodiment, the substrate W is transported into the chamber 10 by a transport arm, placed on the substrate support section 11 by a lifter, and held on the substrate support section 11 by suction, as shown in Figure 2, for example.

[0047] Figure 4 shows an example of the cross-sectional structure of the substrate W prepared in step ST1. As illustrated in Figure 4, the substrate W may be constructed by laminating a silicon-containing film SF and a mask MK in this order on an arbitrary underlayment film UF. The substrate W comprises a silicon-containing film SF and a mask MK disposed on the silicon-containing film SF. The mask MK has at least one opening OP that exposes the silicon-containing film SF. The substrate W may be used in the manufacture of semiconductor devices. Semiconductor devices include, for example, memory devices such as DRAM and 3D-NAND flash memory, and logic devices.

[0048] The underlayer film UF is, in one example, a silicon wafer or an organic film, dielectric film, metal film, or semiconductor film formed on a silicon wafer. The underlayer film UF may be composed of multiple films stacked on top of each other.

[0049] Examples of silicon-containing films SF include spin-on-glass (SOG) films, Si-containing anti-reflective films (SiARC), silicon oxide films, silicon nitride films, silicon oxynitride films, silicon carbide films, silicon carbonitride films, polycrystalline silicon films, and amorphous silicon films. In one embodiment, the silicon-containing film SF includes at least one selected from the group consisting of silicon oxide films, silicon nitride films, and polycrystalline silicon films. As an example, the silicon-containing film is a laminated film of silicon oxide films and silicon nitride films or a laminated film of silicon oxide films and polycrystalline silicon films. For example, the silicon-containing film SF may be constructed by alternately laminating silicon oxide films and silicon nitride films. For example, the silicon-containing film SF may be constructed by alternately laminating silicon oxide films and polycrystalline silicon films. For example, the silicon-containing film SF may be a laminated film including silicon nitride films, silicon oxide films, and polycrystalline silicon films. In one embodiment, the silicon-containing film SF may contain at least one element selected from the group consisting of H, P, N, and B.

[0050] The silicon-containing film SF and the base film UF may be formed by methods such as CVD (Chemical Vapor Deposition), ALD (Atomic Layer Deposition), MLD (Molecular Layer Deposition), PVD (Physical Vapor Deposition), or spin coating. The silicon-containing film SF and the base film UF may be flat films or films with irregularities.

[0051] The mask MK is formed on a silicon-containing film SF and includes a side wall Wa defining at least one opening OP. The mask MK may contain at least one selected from a carbon-containing film, a metal-containing film, and other silicon-containing films (silicon-containing films different from the silicon-containing film SF). In one embodiment, the carbon-containing film may be a spin-on carbon (SOC) film, an amorphous carbon (ACL) film, a photoresist film, a tungsten carbide film, or a boron carbide film. As an example, the carbon-containing film includes an ACL film. In one embodiment, the metal-containing film may be a film containing at least one metal selected from the group consisting of tungsten, molybdenum, ruthenium, titanium, tin, and aluminum. As an example, the metal-containing film includes a tungsten-containing film. In one embodiment, the other silicon-containing film may be a silicon oxide film, a silicon nitride film, a silicon carbonitride film, a polycrystalline silicon film, or a carbon-containing silicon film. The other silicon-containing film may be doped with elements such as phosphorus, boron, or nitrogen. For example, other silicon-containing films include BSi films. In one embodiment, the mask MK may be a single-layer mask consisting of one layer, or a multilayer mask consisting of two or more layers. In one embodiment, the mask MK may be a photoresist. In one embodiment, the mask MK may be a photoresist exposed to extreme ultraviolet light (EUV). For example, a metal-containing resist may be exposed to EUV. In one embodiment, the mask MK may be a chemically amplified resist (CAR). For example, a CAR may be exposed to EUV.

[0052] In the example in Figure 4, the mask MK has a side wall Wa and a top surface Wb. The side wall Wa defines at least one opening OP. The opening OP may have any shape when viewed in plan view of the substrate W, that is, when the substrate W is viewed from top to bottom in Figure 4. 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, and the multiple side walls may define multiple openings OP. Each of the multiple openings OP may have a linear shape and be arranged at regular intervals to form a line and space pattern. Alternatively, each of the multiple openings OP may have a hole shape and form an array pattern. In one embodiment, the dimensions of the opening OP may be 100 nm or less, 50 nm or less, or 30 nm or less. In one embodiment, the opening OP may be formed by lithography. For example, the opening OP may be formed by exposing and developing a photoresist formed on a silicon-containing film SF. When using EUV resist as the photoresist, exposure may be EUV exposure using an EUV exposure apparatus. Development may be dry development or wet development.

[0053] At least a portion of the process for forming the substrate film UF, silicon-containing film SF, and mask MK of the substrate W may be performed in the chamber 10 as part of step ST1. For example, when forming the opening OP of the mask MK by etching, the etching in step ST1 and the processing in step ST2 may be performed consecutively in the chamber 10. In one embodiment, all or part of the substrate W may be formed in an external apparatus or chamber outside the plasma processing apparatus 1, and then the substrate W may be provided into the chamber 10.

[0054] In one embodiment, after the substrate W is placed in the central region 111a of the substrate support 11, the substrate support 11 is controlled to a set temperature by a temperature control module. The set temperature may be, for example, 0°C or lower, -10°C or lower, -20°C or lower, -30°C or lower, -40°C or lower, -50°C or lower, -60°C or lower, or -70°C or lower. In one example, controlling the temperature of the substrate support 11 to the set temperature includes setting the temperature of the heat transfer fluid flowing through the channel 1110a or the heater temperature to the set temperature, or to a temperature different from the set temperature. The timing at which the heat transfer fluid begins to flow through the channel 1110a may be before, after, or simultaneously with the placement of the substrate W on the substrate support 11. Furthermore, the temperature of the substrate support 11 may be controlled to the set temperature before process ST1. That is, the substrate W may be placed on the substrate support 11 after the temperature of the substrate support 11 has been controlled to the set temperature.

[0055] In one embodiment, instead of controlling the substrate support portion 11 to a set temperature, the substrate W may be controlled to a set temperature. Controlling the temperature of the substrate W to a set temperature includes setting the temperature of the substrate support portion 11, the heat transfer fluid flowing through the flow path 1110a, and / or the heater temperature to a set temperature, or to a temperature different from the set temperature.

[0056] (Step ST2: Plasma generation) In step ST2, plasma is generated from a processing gas containing hydrogen fluoride gas (hereinafter also referred to as "HF gas") and bromine-containing gas. In step ST2, a first protective film PM containing bromine is formed up to the lower part of the side wall Wa by the generation of plasma. Also in step ST2, a recess RC is formed in the silicon-containing film SF by the generation of plasma. In one embodiment, the formation of the first protective film PM and the formation of the recess RC are carried out in parallel. In one embodiment, the formation of the first protective film PM proceeds after the formation of the first protective film PM has progressed. In one embodiment, the formation of the first protective film PM proceeds after the formation of the recess RC has progressed. In one embodiment, step ST2 includes supplying the processing gas to the chamber 10 and generating plasma from the processing gas.

[0057] In step ST2, a processing gas is supplied into the chamber 10. The processing gas may be supplied, for example, from the gas supply unit 20 to the chamber 10 via the gas inlet 13c of the central gas injection unit 13. The processing gas includes HF gas and bromine-containing gas. The temperature of the substrate support unit 11 or the substrate W may be controlled to a set temperature, similar to step ST1.

[0058] HF gas may have the highest flow rate (partial pressure) among the process gases, excluding inert gases. For example, the flow rate of HF gas may be 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 95% or more of the total flow rate of the process gases (or the flow rate of all gases excluding inert gases if the process gases include them). The flow rate of HF gas may be less than 100% of the total flow rate of the process gases, 99.5% or less, 98% or less, or 96% or less of the total flow rate of the process gases. For example, the flow rate of HF gas is 70% or more and 96% or less of the total flow rate of the process gases.

[0059] In one embodiment, the bromine-containing gas includes a bromine-containing unsaturated halon gas. In one embodiment, the bromine-containing unsaturated halon gas is R １ R ２ C=CR ３ R ４ (Here, R １ , R ２ , R ３ and R ４ Each of these independently represents a hydrogen atom or a halogen atom, and R １ , R ２ , R ３ and R ４ It contains an unsaturated halone represented by ), where at least one of the atoms is a bromine atom. In one embodiment, the unsaturated halone is C ２ BrF ３ and C ２ H ２ It contains at least one of BrF. For example, an unsaturated halon is C ２ BrF ３ It includes the above. In addition to the above, the bromine-containing gas may further contain HBr.

[0060] In one embodiment, the processing gas further includes at least one gas selected from the group consisting of phosphorus-containing gases, carbon-containing gases, halogen-containing gases different from bromine-containing unsaturated halon gases, and metal-containing gases.

[0061] For example, the phosphorus-containing gas may be, for instance, a phosphorus halogenated gas. Phosphorus halogenated gas is, for example, PF ３ Gas and PF ５ The gas may be a phosphorus fluoride gas containing fluorine as a halogen element. Examples of phosphorus halogen gases include PCL. ３ gas and PCL ５ The gas may be a phosphorus chloride gas containing chlorine as a halogen element. Examples of phosphorus halogenated gases include PBr. ３ Gas, PBr ５ Gas, PI ３ The gas may contain halogen elements such as bromine or iodine. Phosphorus halide gas is, for example, PCLF. ２ Gas, PCL ２ F gas, PCL ２ F ３ The gas may contain two or more halogen elements. The halogenated phosphorus gas may be, for example, oxyphosphorus fluoride gas or oxyphosphorus chloride gas. The halogenated phosphorus gas may be, for example, POF. ３ Gas, POCl ３ Gas, POF ２ Cl ２ Gas, POFCL ２ Gas or POF ２ It can be Cl gas.

[0062] In one embodiment, the carbon-containing gas includes at least one selected from the group consisting of CF-based gases, CHF-based gases, and CH-based gases. In one example, the CF-based 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 gas may be at least one selected from the group consisting of. As an example, CHF-based gas is, in one example, CHF ３ gas, CH ２ F ２ gas, CH ３ F gas, C ２ HF ５ gas and C may be at least one selected from the group consisting of hydrofluorocarbon gas (C ３ H ２ F ４ gas, C ３ H ２ F ６ gas, C ４ H ２ F ６ gas, etc.).

[0063] In one embodiment, the halogen-containing gas different from the bromine-containing unsaturated halon gas contains at least one selected from the group consisting of Cl ２ , HCl, and HBr.

[0064] In one embodiment, the metal-containing gas contains at least one metal selected from the group consisting of tungsten, titanium, ruthenium, and molybdenum. In one embodiment, the metal-containing gas may further contain a halogen. The metal-containing gas is WF ２ gas, WF ４ gas, WF ５ gas, WF ６ gas, WCl ２ gas, WCl ４ gas, WCl ５ gas, WCl ６ gas, MoF ４ gas, MoF ６ gas, MoCl ６ gas, TiCl[[ID=Z6]] ４ gas, etc.

[0065] In one embodiment, the processing gas may further contain an inert gas. As an example, the inert gas is, in one example, a noble gas such as Ar gas, He gas, Kr gas, or N ２ gas.

[0066] In one embodiment, the processing gas may contain a gas capable of generating hydrogen fluoride species (HF species) in the plasma, instead of some or all of the HF gas. The HF species includes at least one of hydrogen fluoride gas, radicals, and ions. The gas capable of generating HF species may be, for example, a CHF-based gas. The CHF-based gas may have two or more, three or more, or four or more carbon atoms.

[0067] A gas capable of generating HF species may be, for example, a mixed gas containing a hydrogen source and a fluorine source. The hydrogen source may be, for example, H ２ Gas, NH ３ Gas, H ２ O gas, H ２ O ２ It may be at least one selected from the group consisting of gases and CH-based gases. The fluorine source is, for example, NF ３ Gas, SF ６ Gas, WF ６ Gas or XeF ２ Any fluorine-containing gas that does not contain carbon, like a gas, is acceptable. Alternatively, the fluorine source may be a fluorine-containing gas that does contain carbon, such as CF-based gases and CHF-based gases.

[0068] Next, plasma is generated from the processing gas in the chamber 10. In one embodiment, 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 processing gas in the plasma processing space 10s. At this time, a bias signal may be supplied to the substrate support 11. The bias signal may be a bias RF signal supplied from the RF power supply 31, or a bias DC signal supplied from the DC power supply 32. In this case, a bias potential is generated between the plasma and the substrate W.

[0069] Figure 5 shows an example of the cross-sectional structure of the substrate W during process ST2. In process ST2, bromine dissociated from the bromine-containing gas in the processing gas into the plasma is deposited on the mask MK. This forms a first protective film PM on the mask MK. The first protective film PM contains bromine. In one embodiment, the first protective film PM is formed from the upper part (hereinafter also referred to as "second region R2") to the lower part (hereinafter also referred to as "first region R1") of the side wall Wa of the mask MK. In one embodiment, the first region R1 of the side wall Wa may be a region including the boundary position P1 between the mask MK and the silicon-containing film SF to position P2 at half the thickness (50%) of the mask MK. The second region R2 may be a region including the position P2 to position P3 on the upper surface of the mask MK. In one embodiment, the first protective film PM may be formed on a part of the first region R1, or it may be formed on the whole of it. In one embodiment, the first protective film PM may be formed on a part of the second region R1, or on the entire region. In one embodiment, the first protective film PM may also be formed on the upper surface Wb of the mask MK, as shown in Figure 5.

[0070] Active species such as ions and radicals in the plasma are attracted to the substrate W. At this time, the mask MK functions as a mask, and the portion of the silicon-containing film SF exposed to the opening OP is selectively etched by active species in the plasma (e.g., HF species). As a result, a recess RC is formed as shown in Figure 5. At this time, the first protective film PM functions as a protective film for the side wall Wa of the mask MK. The first protective film PM is formed from the upper part (second region R2) to the lower part (first region R1) of the side wall Wa of the mask MK. Therefore, etching of the side wall Wa in the lateral direction (left-right direction in Figure 5) by active species in the plasma can be suppressed not only on the upper part of the side wall Wa of the mask MK but also on the lower part. As a result, the occurrence of shape abnormalities such as bowing in the recess RC can be suppressed.

[0071] When the bromine-containing gas includes a bromine-containing unsaturated halon gas, the first protective film PM may be formed further down from the side wall Wa, for example, to the boundary position P1 with the silicon-containing film or its vicinity. In this case, the occurrence of shape abnormalities such as bowing can be further suppressed. In one embodiment, when the bromine-containing gas includes a bromine-containing unsaturated halon gas and a hydrogen bromide gas, the flow rate of the bromine-containing unsaturated halon gas may be greater than the flow rate of the hydrogen bromide gas. As an example, when the bromine-containing gas is C ２ BrF ３ When gas and hydrogen bromide gas are included, C in chlorine-containing gas ２ BrF ３ The gas flow rate can be greater than the hydrogen bromide gas flow rate.

[0072] In one embodiment, step ST2 may further include forming a second protective film (not shown) on at least a portion of the side wall Wc defining the recess RC. In one embodiment, the second protective film may include reaction products generated by etching. For example, if the silicon-containing film includes a silicon nitride film, the second protective film may include ammonium silicofluoride (NH4) ４ ) ２ SiF ６ (AFS) may be included. In one embodiment, the second protective film may be bromine-free or contain a lower concentration of bromine than the first protective film PM.

[0073] In one embodiment, during the formation process of the recess RC, the bottom of the recess reaches the underlying film UF, thereby exposing at least a portion of the underlying film UF to the opening OP. Step ST2 may be terminated after at least a portion of the underlying film UF is exposed, or before (for example, immediately before) at least a portion of the underlying film UF is exposed. Alternatively, step ST2 may be terminated when a given stop condition is met. The stop condition may be, for example, the etching time, or the depth of the recess RC. At the end of etching, the operation may be the cessation of the source RF signal, bias RF signal, bias DC signal, and the supply of the first processing gas.

[0074] <Examples> Next, we will describe examples of evaluating pattern shapes based on this method. This disclosure is not limited in any way by the following examples.

[0075] (Reference Example 1) An apparatus having the same configuration as the plasma processing apparatus 1 shown in Figure 2 was prepared. A substrate was placed on the substrate support part 11 of the apparatus. This substrate had the same configuration as the substrate W shown in Figure 4. A laminated film of a silicon oxide film and a silicon nitride film was used as the silicon-containing film SF. An amorphous carbon film was used as the mask MK. Multiple openings OP that expose the silicon-containing film SF were formed in the mask MK. That is, the multiple openings OP were formed to constitute a contact hole pattern.

[0076] Etching was performed using the above plasma processing apparatus to form a contact hole pattern. During etching, HF gas, HBr gas and PF gas were used. ３ A processing gas containing gas was used.

[0077] As a result of the etching described above, it was confirmed that a "boeing" shape (hereinafter, this shape will also be referred to as the "boeing shape") was formed in the recesses created in the silicon-containing film. In addition, a protective film originating from bromine-containing gas (HBr gas) was observed to form on the upper part of the side wall that defines the opening OP of the mask, in addition to the upper surface of the mask.

[0078] (Reference Example 2) The contact hole pattern was formed in the same manner as in Reference Example 1, except that the amount of HBr gas was changed to 2.5 times the amount in the etching conditions of Reference Example 1.

[0079] As a result of the etching described above, the bowing shape of the recesses formed in the silicon-containing film was similar to that of Reference Example 1. That is, the maximum opening dimension of the bowing in Reference Example 2 (hereinafter also referred to as "BCD") was 95.2% of the BCD of Reference Example 1. In Reference Example 2, as in Reference Example 1, a protective film originating from bromine-containing gas (HBr gas) was observed not only on the upper surface of the mask but also on the upper part of the side wall that defines the opening OP of the mask.

[0080] (Example 1) Under the etching conditions of Reference Example 1, C is further added as the processing gas. ２ BrF ３ The contact hole pattern was formed in the same manner as in Reference Example 1, except that gas was used.

[0081] As a result of the etching described above, an improvement was observed in the bowing shape of the recesses formed in the silicon-containing film. Specifically, the BCD of Example 1 was 92.6% of the BCD of Reference Example 1. In Example 1, in addition to the upper surface of the mask, the entire area from the upper to the lower part of the side wall of the mask (the boundary between the mask and the silicon-containing film) was treated with bromine-containing gas (C ２ BrF ３ A protective film originating from the gas was observed. Thus, when a protective film originating from the bromine-containing gas was formed up to the lower part of the side wall defining the opening OP of the mask, a tendency for bowing to be suppressed was observed. In addition, as the bromine-containing gas, C ２ BrF ３ When using unsaturated halons such as these, a protective film originating from bromine-containing gas tended to form down to the lower part of the side wall.

[0082] Embodiments of this disclosure further include the following embodiments:

[0083] (Note 1) An etching method comprising: (a) a step of preparing a substrate on a substrate support portion, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, the mask comprising a side wall defining at least one opening that exposes the silicon-containing film; and (b) a step of generating plasma from a processing gas containing hydrogen fluoride and a bromine-containing gas, comprising forming a first protective film containing bromine up to the lower part of the side wall and forming a recess in the silicon-containing film.

[0084] (Note 2) The etching method according to Note 1, wherein the lower part of the side wall includes the boundary with the silicon-containing film.

[0085] (Note 3) The etching method according to Note 1 or 2, wherein the bromine-containing gas includes a bromine-containing unsaturated halon gas.

[0086] (Note 4) The bromine-containing gas is R１ R ２ C=CR ３ R ４ (Here, R １ , R ２ , R ３ and R ４ Each of these independently represents a hydrogen atom or a halogen atom, and R １ , R ２ , R ３ and R ４ An etching method according to any one of the appendices 1 to 3, comprising an unsaturated halon represented by (at least one of which is a bromine atom).

[0087] (Note 5) The unsaturated halons mentioned above are C ２ BrF ３ The etching method described in Appendix 4, including the method described in Appendix 4.

[0088] (Note 6) The etching method according to any one of Notes 1 to 5, wherein (b) further comprises forming a second protective film on at least a portion of the side wall defining the recess.

[0089] (Note 7) The etching method according to Note 6, wherein the second protective film does not contain bromine, or contains a lower concentration of bromine than the first protective film.

[0090] (Note 8) (c) The etching method according to any one of Notes 1 to 8, further comprising the step of controlling the temperature of the substrate support portion to 0°C or less between (a) and (b).

[0091] (Note 9) The etching method according to Note 3, wherein the processing gas further comprises at least one gas selected from the group consisting of phosphorus-containing gas, carbon-containing gas, halogen-containing gas different from the bromine-containing unsaturated halon gas, and metal-containing gas.

[0092] (Note 10) The phosphorus-containing gas is PF ３ and POCl ３ The etching method described in Appendix 9, comprising at least one of the following.

[0093] (Note 11) The etching method according to Note 9 or 10, wherein the carbon-containing gas includes at least one selected from the group consisting of CF-based gases, CHF-based gases, and CH-based gases.

[0094] (Note 12) The halogen-containing gas is Cl ２ The etching method according to any one of the appendices 9 to 11, comprising at least one selected from the group consisting of HCl and HBr.

[0095] (Note 13) The metal-containing gas is WF ６ and MoF ６ An etching method according to any one of appendices 9 to 12, comprising at least one of the above.

[0096] (Note 14) The etching method according to any one of Notes 1 to 13, wherein the silicon-containing film comprises at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, and a polycrystalline silicon film.

[0097] (Note 15) The etching method according to any one of Notes 1 to 14, wherein the mask includes at least one selected from the group consisting of a carbon-containing film, a metal-containing film, and other silicon-containing films.

[0098] (Note 16) The etching method according to Note 15, wherein the carbon-containing film includes an amorphous carbon film.

[0099] (Note 17) The etching method according to Note 15 or 16, wherein the metal-containing film includes a tungsten-containing film.

[0100] (Note 18) The etching method according to any one of Notes 15 to 17, wherein the other silicon-containing film includes a BSi film.

[0101] (Note 19) A plasma processing apparatus comprising: a chamber; a substrate support portion provided within the chamber; a gas supply portion for supplying a processing gas into the chamber; a plasma generation portion for generating plasma from the processing gas; and a control portion, wherein the control portion is configured to use the gas supply portion and the plasma generation portion to perform the following controls: (a) a control for preparing a substrate on the substrate support portion, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, and the mask comprises a side wall defining at least one opening for exposing the silicon-containing film; and (b) a control for generating plasma from a processing gas containing hydrogen fluoride and a bromine-containing gas, wherein the control includes forming a first protective film containing bromine up to the bottom of the side wall and forming a recess in the silicon-containing film.

[0102] (Note 20) The plasma processing apparatus described in Note 19, wherein the bromine-containing gas includes a bromine-containing unsaturated halon gas.

[0103] (Note 21) The bromine-containing gas is R １ R ２ C=CR ３ R ４ (Here, R １ , R ２ , R ３ and R ４ Each of these independently represents a hydrogen atom or a halogen atom, and R １ , R ２ , R ３ and R ４ A plasma apparatus according to Appendix 19 or 20, comprising an unsaturated halon represented by (at least one of which is a bromine atom).

[0104] (Note 22) The unsaturated halons mentioned above are C ２ BrF ３ A plasma processing apparatus as described in Appendix 21, including the one described above.

[0105] (Note 23) The plasma processing apparatus according to any one of Notes 19 to 22, further comprising a temperature control module for adjusting the temperature of the substrate, wherein the control unit is configured to perform control that further includes control for controlling the temperature of the substrate support portion to 0°C or less using the temperature control module.

[0106] The embodiments described above are for illustrative purposes only and are not intended to limit the scope of this disclosure. Each embodiment can be modified in various ways without departing from the scope and spirit of this disclosure. For example, some components of one embodiment can be added to other embodiments, or some components of one embodiment can be replaced with corresponding components of other embodiments.

[0107] 1...Plasma processing apparatus, 2...Control unit, 10...Plasma processing chamber, 11...Substrate support part, W...Substrate, SF...Silicon-containing film, MK...Mask, OP...Opening, Wa...Side wall, RC...Recess, R1...First region, R2...Second region, PM...First protective film

Claims

1. An etching method comprising: (a) a step of preparing a substrate on a substrate support portion, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, the mask comprising a side wall defining at least one opening that exposes the silicon-containing film; and (b) a step of generating plasma from a processing gas comprising hydrogen fluoride gas and bromine-containing gas, comprising forming a first protective film containing bromine up to the lower part of the side wall and forming a recess in the silicon-containing film.

2. The etching method according to claim 1, wherein the lower part of the side wall includes the boundary with the silicon-containing film.

3. The etching method according to claim 1, wherein the bromine-containing gas includes a bromine-containing unsaturated halon gas.

4. The bromine-containing gas is R ４ , ２ , ３ R ２ C═CR ３ R ４ (where R １ , R ２ , R ３ and R ４ each independently represent a hydrogen atom or a halogen atom, and at least one of R １ , R ２ , R ３ and R ４ is a bromine atom.). The etching method according to claim 1, comprising an unsaturated halon represented by 5. The aforementioned unsaturated halons are C ２ BrF ３ The etching method according to claim 4, including the method described in claim 4.

6. The etching method according to claim 1, wherein (b) further comprises forming a second protective film on at least a portion of the side wall defining the recess.

7. The etching method according to claim 6, wherein the second protective film does not contain bromine, or contains bromine at a lower concentration than the first protective film.

8. (c) The etching method according to claim 1, further comprising the step of controlling the temperature of the substrate support portion to 0°C or less between (a) and (b).

9. The etching method according to claim 3, wherein the processing gas further comprises at least one gas selected from the group consisting of phosphorus-containing gas, carbon-containing gas, halogen-containing gas different from the bromine-containing unsaturated halon gas, and metal-containing gas.

10. The phosphorus-containing gas is PF ３ and POCl ３ The etching method according to claim 9, comprising at least one of the following.

11. The etching method according to claim 9, wherein the carbon-containing gas comprises at least one selected from the group consisting of CF-based gases, CHF-based gases, and CH-based gases.

12. The halogen-containing gas is Cl ２ The etching method according to claim 9, comprising at least one selected from the group consisting of HCl and HBr.

13. The metal-containing gas is WF ６ and MoF ６ The etching method according to claim 9, comprising at least one of the following.

14. The etching method according to claim 1, wherein the silicon-containing film comprises at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, and a polycrystalline silicon film.

15. The etching method according to claim 1, wherein the mask comprises at least one selected from the group consisting of a carbon-containing film, a metal-containing film, and other silicon-containing films.

16. The etching method according to claim 15, wherein the carbon-containing film includes an amorphous carbon film.

17. The etching method according to claim 15, wherein the metal-containing film includes a tungsten-containing film.

18. The etching method according to claim 15, wherein the other silicon-containing film includes a BSi film.

19. A plasma processing apparatus comprising: a chamber; a substrate support portion provided within the chamber; a gas supply portion for supplying a processing gas into the chamber; a plasma generation portion for generating plasma from the processing gas; and a control portion, wherein the control portion is configured to use the gas supply portion and the plasma generation portion to perform the following controls: (a) a control for preparing a substrate on the substrate support portion, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, and the mask comprises a side wall defining at least one opening that exposes the silicon-containing film; and (b) a control for generating plasma from a processing gas containing hydrogen fluoride gas and bromine-containing gas, wherein the control includes forming a first protective film containing bromine up to the bottom of the side wall and forming a recess in the silicon-containing film.

20. The plasma apparatus according to claim 19, wherein the bromine-containing gas includes a bromine-containing unsaturated halon gas.

21. The bromine-containing gas is R １ R ２ C=CR ３ R ４ (Here, R １ , R ２ , R ３ and R ４ Each of these independently represents a hydrogen atom or a halogen atom, and R １ , R ２ , R ３ and R ４ The plasma apparatus according to claim 19, comprising an unsaturated halon represented by (at least one of which is a bromine atom).

22. The aforementioned unsaturated halons are C ２ BrF ３ The plasma processing apparatus according to claim 21, including the following:

23. The plasma processing apparatus according to claim 19, further comprising a temperature control module for adjusting the temperature of the substrate, wherein the control unit is configured to perform control that further includes controlling the temperature of the substrate support portion to 0°C or less using the temperature control module.

Images