Etching method and plasma processing apparatus

Abstract

This invention provides a technology that can suppress shape abnormalities during etching. [Solution] The etching method includes (a) providing a substrate in a chamber, the substrate comprising a silicon-containing film and a mask on the silicon-containing film, the mask comprising at least one opening, and (b) etching the silicon-containing film to form a recess, wherein (b) comprises (b1) etching the silicon-containing film with plasma generated from a first processing gas, the first processing gas comprising hydrogen fluoride gas and bromine-containing gas, and (b2) etching the silicon-containing film with plasma generated from a second processing gas, the second processing gas comprising hydrogen fluoride gas and chlorine-containing gas.

Description

TECHNICAL FIELD

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

BACKGROUND ART

[0002] JP 2016-39309A discloses a processing gas containing hydrogen gas, fluorohydrocarbon gas, fluorine-containing gas, hydrocarbon gas, boron trichloride gas, and nitrogen gas as a processing gas used for plasma etching of a silicon-containing film. JP 2014-17406 A discloses a processing gas containing boron as a processing gas used for plasma etching of a silicon-containing film.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0003]

PATENT DOCUMENT 1

PATENT DOCUMENT 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] The present disclosure provides a technique capable of suppressing shape abnormality in etching.

MEANS FOR SOLVING THE PROBLEMS

[0005] An etching method in one exemplary embodiment of the present disclosure includes (a) providing a substrate in a chamber, the substrate comprising a silicon-containing film and a mask on the silicon-containing film, the mask comprising at least one opening, and (b) etching the silicon-containing film to form a recess, wherein (b) includes (b1) etching the silicon-containing film with plasma generated from a first processing gas, the first processing gas comprising hydrogen fluoride gas and bromine-containing gas, and (b2) etching the silicon-containing film with plasma generated from a second processing gas, the second processing gas comprising hydrogen fluoride gas and chlorine-containing gas. [Effects of the Invention]

[0006] According to one exemplary embodiment of the present disclosure, a technique can be provided that can suppress shape abnormalities in etching. [Brief explanation of the drawing]

[0007] [Figure 1] This is a diagram illustrating an example configuration of a plasma processing system. [Figure 2] This is a diagram illustrating an example of the configuration of a plasma processing apparatus. [Figure 3] This is a flowchart illustrating an example of an etching method. [Figure 4] This is a diagram illustrating an example of the cross-sectional structure of the substrate in process ST1. [Figure 5A] This is a flowchart illustrating an example of process ST2. [Figure 5B] This is a flowchart illustrating an example of process ST2. [Figure 5C] This is a flowchart illustrating an example of process ST2. [Figure 6A] This figure shows an example of the cross-sectional structure of the substrate W during processing in step ST2. [Figure 6B] This figure shows an example of the cross-sectional structure of the substrate W during processing in step ST2. [Figure 6C]This is a diagram showing an example of the cross-sectional structure of the substrate W during the process of step ST2. [Figure 6D] This is a diagram showing an example of the cross-sectional structure of the substrate W during the process of step ST2. [Figure 7] This is a diagram showing the experimental conditions and experimental results of Examples and Reference Examples. [Mode for Carrying Out the Invention]

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

[0009] In one exemplary embodiment, there is provided an etching method, comprising: (a) providing a substrate in a chamber, wherein the substrate includes a silicon-containing film and a mask on the silicon-containing film, the mask including at least one opening; and (b) etching the silicon-containing film to form a recess, wherein (b) includes (b1) etching the silicon-containing film with plasma generated from a first processing gas, the first processing gas containing hydrogen fluoride gas and a bromine-containing gas, and (b2) etching the silicon-containing film with plasma generated from a second processing gas, the second processing gas containing hydrogen fluoride gas and a chlorine-containing gas.

[0010] In one exemplary embodiment, the silicon-containing film contains nitrogen.

[0011] In one exemplary embodiment, at least one of the first processing gas and the second processing gas contains a nitrogen-containing gas.

[0012] In one exemplary embodiment, (b1) includes forming a protective film containing bromine on the sidewall of the recess.

[0013] In one exemplary embodiment, (b2) includes removing the reaction product adhering to the sidewall of the recess.

[0014] In one exemplary embodiment, (b2) includes widening the opening dimension of the bottom surface of the recess.

[0015] In one exemplary embodiment, the first processing gas contains no chlorine-containing gas, or contains a chlorine-containing gas at a flow rate ratio smaller than the flow rate ratio of the chlorine-containing gas contained in the second processing gas.

[0016] In one exemplary embodiment, the second processing gas contains no bromine-containing gas, or contains a bromine-containing gas at a flow rate ratio smaller than the flow rate ratio of the bromine-containing gas contained in the first processing gas.

[0017] In one exemplary embodiment, (b) includes repeating a cycle including (b1) and (b2) a plurality of times.

[0018] In one exemplary embodiment, the ratio of the processing time of (b2) to the processing time of (b1) is changed according to the aspect ratio of the recess.

[0019] In one exemplary embodiment, the bromine-containing gas is at least one gas selected from the group consisting of Br₂, HBr, CBr₂F₂, C₂F₅Br, PBr₃, PBr₅, POBr₃ and BBr₃.

[0020] In one exemplary embodiment, the chlorine-containing gas is at least one gas selected from the group consisting of Cl₂, SiCl₂, SiCl₄, CCl₄, SiH₂Cl₂, Si₂Cl₆, CHCl₃, SO₂Cl₂, BCl₃, PCl₃, PCl₅ and POCl₃.

[0021] In one exemplary embodiment, in (a), the substrate is disposed on a substrate support portion within a chamber, and in (b), the temperature of the substrate or the substrate support portion is controlled to 0°C or lower.

[0022] In one exemplary embodiment, the first processing gas or the second processing gas further contains at least one gas selected from the group consisting of a phosphorus-containing gas, a metal-containing gas, a carbon-containing gas, a carbon-free fluorine-containing gas, and an inert gas.

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

[0024] In one exemplary embodiment, a plasma processing apparatus is provided comprising a chamber, a substrate support within the chamber, a plasma generation unit, and a control unit, wherein the control unit is configured to perform (a) providing a substrate having a silicon-containing film and a mask on the silicon-containing film on the substrate support within the chamber, wherein the mask includes at least one opening, and (b) etching the silicon-containing film on the substrate on the substrate support unit to form a recess, wherein (b) comprises (b1) generating plasma from a second processing gas containing bromine gas by the plasma generation unit to etch the silicon-containing film, and (b2) generating plasma from a first processing gas containing chlorine gas by the plasma generation unit to etch the silicon-containing film.

[0025] 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.

[0026] (First embodiment) <An example of a plasma treatment system> Figure 1 is a diagram illustrating an example 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.

[0027] 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 a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron cyclotron resonance (ECR) plasma, a helicon wave excited plasma (HWP), or a surface wave plasma (SWP), etc. Various types of plasma generation units, including an AC (alternating current) plasma generation unit and a DC (direct current) plasma generation unit, 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.

[0028] 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 each element of the plasma processing apparatus 1 to perform the various processes described herein. In one embodiment, some 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 implemented by the processing unit 2a1 described herein may be implemented in a circuit or processing circuitry, including a general-purpose processor, an application-specific processor, integrated circuits, ASICs (Application Specific Integrated Circuits), a CPU (Central Processing Unit), conventional circuitry, and / or a combination thereof, programmed to implement the functions described herein. A processor is considered a circuit or processing circuit, including transistors and other circuitry. A processor may be a programmed processor that executes a program stored in the storage unit 2a2. This program may be stored in the memory unit 2a2 in advance, or it may be retrieved via a medium when needed. The retrieved program is stored in the memory unit 2a2 and read from the memory 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 memory 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.

[0029] The following describes an example configuration of a capacitively coupled plasma processing apparatus as an example of plasma processing apparatus 1. Figure 2 is a diagram illustrating an example configuration of a capacitively coupled plasma processing apparatus.

[0030] 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.

[0031] 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.

[0032] 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 on both the electrostatic chuck 1111 and the annular insulating member. In addition, at least one bias electrode, electrically connected or coupled to the power supply 31 and / or power supply 32 described later, may be placed within 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 in 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 in 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one 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.

[0037] 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. Thus, 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.

[0038] 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. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0039] 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. If 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 lower frequency 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.

[0040] 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 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 configured to generate a second voltage signal. The generated second voltage signal is applied to at least one upper electrode.

[0041] 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 multiple 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 rectangular, trapezoidal, triangular, 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.

[0042] 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.

[0043] <An example of a plasma treatment method> Figure 3 is a flowchart of a plasma processing method (hereinafter also referred to as "this processing method") according to one exemplary embodiment. As shown in Figure 3, this processing method includes a step ST1 for providing a substrate and a step ST2 for performing etching. The processing in each step may be carried out using the plasma processing system shown in Figure 1 or Figure 2. In the following description, we will explain using as an example a case in which the control unit 2 controls each part of the plasma processing apparatus 1 shown in Figure 2 to perform method MT on the substrate W.

[0044] (Step ST1: Provision of substrate) In step ST1, the substrate W is placed in the plasma processing space 10s of the plasma processing apparatus 1. The substrate W is placed in the central region 111a of the substrate support section 11. The substrate W is then placed on the substrate support section 11 by a lifter and held in place by an electrostatic chuck 1111, for example, as shown in Figure 2.

[0045] Figure 4 shows an example of the cross-sectional structure of the substrate W provided in process ST1. The substrate W has a silicon-containing film SF and a mask MK laminated in that order on a base film UF. 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.

[0046] 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.

[0047] The silicon-containing film SF is the film to be etched in this processing method. In one embodiment, the silicon-containing film SF may be a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a polycrystalline silicon film. In one embodiment, the silicon-containing film SF may be a film containing nitrogen. In one embodiment, the silicon-containing film SF may be a laminated film in which a plurality of films are stacked. In one example, the silicon-containing film SF may include a laminated structure comprising two or more films selected from the group consisting of a single-crystal silicon film, a polycrystalline silicon film, a silicon oxide film, and a silicon nitride film. For example, the silicon-containing film SF may include a laminated structure in which silicon oxide films and silicon nitride films are alternately stacked. In one embodiment, the silicon-containing film SF may be doped with at least one element selected from the group consisting of hydrogen (H), phosphorus (P), nitrogen (N), and boron (B).

[0048] Mask MK functions as a mask in etching the silicon-containing film SF. Mask MK may be a single-layer mask consisting of one type of film, or a multilayer mask consisting of two or more films. In one embodiment, mask MK may include at least one film selected from the group consisting of carbon-containing films and metal-containing films. The carbon-containing film may, in one example, be a spin-on carbon (SOC) film, an amorphous carbon (ACL) film, a photoresist film, a tungsten carbide film, or a boron carbide film. The amorphous carbon (ACL) film may be doped with elements 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). In one example, the metal-containing film includes 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 includes 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.

[0049] As shown in Figure 4, the mask MK defines at least one opening OP on the silicon-containing film SF. The opening OP is a space on the silicon-containing film SF surrounded by the side walls 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.

[0050] The aperture 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 apertures OP. Each of the multiple apertures OP may have a linear shape and be arranged at regular intervals to form a line and space pattern. Alternatively, each of the multiple apertures OP may have a hole shape and form an array pattern. In one embodiment, the aperture dimensions of the apertures OP may be 100 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, or 20 nm or less.

[0051] The undercoat film UF, the silicon-containing film SF, and the mask MK may each be formed by any method. For example, the undercoat film UF, the silicon-containing film SF, and the mask MK may be formed by CVD, ALD, PVD, spin coating, etc. The opening OP may be formed by etching the mask MK. Alternatively, the opening OP may be formed by lithography. As an example, the opening OP may be formed by exposing and developing a photoresist formed on the silicon-containing film SF. Development may be dry development or wet development. The undercoat film UF, the silicon-containing film SF, and the mask MK may be flat films or films with irregularities. The substrate W may also have other films beneath the undercoat film UF. In this case, recesses corresponding to the opening OP may be formed in the silicon-containing film SF and the undercoat film UF and used as masks for etching the other films.

[0052] At least part of the process for forming each film on the substrate W may be performed within the space of the plasma processing chamber 10. For example, the step of etching the mask MK to form an opening OP may be performed in the plasma processing chamber 10. That is, the etching of the opening OP and the silicon-containing film SF, described later, may be performed consecutively within the same chamber. Alternatively, after all or part of each film on the substrate W has been formed in an external apparatus or chamber of the plasma processing apparatus 1, the substrate W may be brought into the plasma processing space 10s of the plasma processing apparatus 1 and placed in the central region 111a of the substrate support section 11 to provide the substrate.

[0053] After the substrate W is placed in the central region 111a of the substrate support section 11, the temperature of the substrate support section 11 is adjusted to a set temperature by the temperature control module. The set temperature may be, for example, 70 degrees or less, 0 degrees or less, -10 degrees or less, -20 degrees or less, -30 degrees or less, -40 degrees or less, -50 degrees or less, -60 degrees or less, or -70 degrees or less. In one example, adjusting or maintaining the temperature of the substrate support section 11 includes adjusting or maintaining the temperature of the heat transfer fluid flowing through the channel 1110a to the set temperature or a temperature different from the set temperature. In another example, adjusting or maintaining the temperature of the substrate support section 11 includes controlling the pressure of the heat transfer gas (e.g., He) between the electrostatic chuck 1111 and the back surface of the substrate W. 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 section 11. In addition, in this processing method, the temperature of the substrate support section 11 may be adjusted to the set temperature before step ST1. In other words, the substrate W may be provided to the substrate support 11 after the temperature of the substrate support 11 has been adjusted to the set temperature. In one embodiment, instead of controlling the substrate support 11 to the set temperature, the substrate W may be controlled to the set temperature. Controlling the temperature of the substrate W to the set 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 set temperature, or to a temperature different from the set temperature.

[0054] (Process ST2: Etching) In step ST2, the silicon-containing film SF of the substrate W is etched. Step ST2 includes a first etching step ST21 and a second etching step ST22. In one embodiment, as shown in Figure 3, step ST22 may be executed after step ST21. In one embodiment, step ST21 may be executed after step ST22. Step ST2 may also include a step ST23 for determining whether the etching stop condition is met. That is, steps ST21 and ST22 may be repeated alternately until it is determined in step ST23 that the stop condition is met. In one embodiment, as shown in Figure 3, step ST23 may be executed after step ST22. In one embodiment, step ST23 may be executed after step ST21, or after each of steps ST21 and ST22. During the processing in step ST2, the temperature of the substrate support 11 may be maintained at the set temperature adjusted in step ST1.

[0055] (Process ST21: First etching process) In step ST21, the silicon-containing film SF is etched using plasma generated from the first processing gas. First, the first processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The first processing gas includes hydrogen fluoride (HF) gas and bromine-containing gas. Next, a source RF signal is supplied to the lower electrode of the substrate support unit 11 and / or the upper electrode of the shower head 13. This generates a high-frequency electric field between the shower head 13 and the substrate support unit 11, and plasma is generated from the first processing gas in the plasma processing space 10s. In addition, a bias signal is supplied to the lower electrode of the substrate support unit 11, generating a bias potential between the plasma and the substrate W. The bias potential attracts active species such as ions and radicals in the plasma to the substrate W, and these active species etch the silicon-containing film SF.

[0056] (Process ST22: Second etching process) In the second etching step ST22, the silicon-containing film SF is etched using plasma generated from the second processing gas. First, the second processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The second processing gas contains hydrogen fluoride gas and chlorine-containing gas. Next, a source RF signal is supplied to the lower electrode of the substrate support unit 11 and / or the upper electrode of the shower head 13. This generates a high-frequency electric field between the shower head 13 and the substrate support unit 11, and plasma is generated from the second processing gas in the plasma processing space 10s. A bias signal is also supplied to the lower electrode of the substrate support unit 11, generating a bias potential between the plasma and the substrate W. The bias potential attracts active species such as ions and radicals in the plasma to the substrate W, and these active species etch the silicon-containing film SF, forming a recess based on the shape of the opening OP of the mask MK.

[0057] In steps ST21 and ST22, the bias signal may be a bias RF signal supplied from the second RF generation unit 31b. Alternatively, the bias signal may be a bias DC signal supplied from the DC generation unit 32a. Both the source RF signal and the bias signal may be continuous waves or pulsed waves, or one may be a continuous wave and the other a pulsed wave. If both the source RF signal and the bias signal are pulsed waves, the periods of both pulsed waves may be synchronized. The duty cycle of the pulsed wave may be set as appropriate, for example, 1 to 80%, or 5 to 50%. The duty cycle is the proportion of the pulsed wave period in which the power or voltage level is high. When a bias DC signal is used, the pulsed wave may have a rectangular, trapezoidal, triangular, or a combination thereof waveform. The polarity of the bias DC signal may be negative or positive, as long as the potential of the substrate W is set to create a potential difference between the plasma and the substrate to attract ions.

[0058] (Process ST23: Termination Determination) In step ST23, it is determined whether or not a stop condition is met. The stop condition may be, for example, whether the number of repetitions of a cycle consisting of steps ST21 and ST22 has reached a given number. Another stop condition may be whether the etching time has reached a given time. Yet another stop condition may be whether the depth of the recess formed by etching has reached a given depth. Regardless of whether the first step performed was ST21 or ST22, the process may be stopped after performing step ST21, or after performing step ST22. If it is determined that the stop condition is not met in step ST23, the cycle including steps ST21 and ST22 is repeated. If it is determined that the stop condition is met in step ST23, this process method is terminated.

[0059] (Composition of the processed gas) As described above, the first treatment gas contains hydrogen fluoride gas and bromine-containing gas. The second treatment gas also contains hydrogen fluoride gas and chlorine-containing gas.

[0060] In one embodiment, the first treatment gas does not contain chlorine-containing gas, or contains chlorine-containing gas at a flow rate ratio smaller than that of the chlorine-containing gas contained in the second treatment gas.

[0061] In one embodiment, the second processing gas does not contain bromine-containing gas, or contains bromine-containing gas at a flow rate ratio smaller than that of the bromine-containing gas contained in the first processing gas.

[0062] Figures 5A to 5C are timing charts showing an example of the flow rates of HF gas, bromine-containing gas, and chlorine-containing gas in the first or second process gas (hereinafter collectively referred to as "process gas") in process ST2. In Figures 5A to 5C, the vertical axis represents the flow rate of each gas, and the horizontal axis represents time. In Figure 5A, F1 is a flow rate greater than 0. In Figure 5B, F2 is a flow rate greater than 0, and F3 is a flow rate less than F2 or 0. In one example, the relationship F1 > F2 > F3 holds. In Figure 5C, F4 is a flow rate greater than 0, and F5 is a flow rate less than F4 or 0. In one example, the relationship F1 > F4 > F5 holds. In Figures 5A to 5C, periods T1 (time t0 to time t1) and T3 (time t2 to time t3) correspond to process ST21. Furthermore, periods T2 (times t1 to t2) and T4 (times t3 to t4) correspond to process ST22. The ratio of the duration of process ST21 (periods T1-T3) to the duration of process ST22 (periods T2-T4) may be set as appropriate. This ratio may be set in the range of, for example, 1:3 to 3:1. This ratio may be changed, for example, as the etching process progresses. Also, the duration of process ST21 may be the same or different for each cycle. That is, periods T1 and T3 may be the same or different. Similarly, the duration of process ST22 may be the same or different for each cycle. That is, periods T2 and T4 may be the same or different.

[0063] In one embodiment, in the process gas (first process gas or second process gas), the HF gas may have the highest flow rate (partial pressure) among the process gases, excluding the inert gas. For example, the flow rate of the 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 gas (or the flow rate of all gases excluding the inert gas if the process gas includes it). The flow rate of the HF gas may be less than 100% of the total flow rate of the process gas, 99.5% or less, 98% or less, or 96% or less of the total flow rate of the process gas. For example, the flow rate of the HF gas is 70% or more and 96% or less of the total flow rate of the process gas.

[0064] In one embodiment, the processing gas (first processing gas or second processing gas) may include 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.

[0065] Gases capable of producing HF species may be, for example, hydrofluorocarbon gases. Hydrofluorocarbon gases may have 2 or more carbon atoms, 3 or more, or 4 or more. Examples of hydrofluorocarbon gases include CH2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, and C5H2F 10 It is at least one selected from the group consisting of gases and C5H3F7 gas. Hydrofluorocarbon gases, for example, are at least one selected from the group consisting of CH2F2 gas, C3H2F4 gas, C3H2F6 gas and C4H2F6 gas.

[0066] A gas capable of producing HF species may be, for example, a mixed gas containing a hydrogen source and a fluorine source. The hydrogen source may be at least one selected from the group consisting of, for example, H2 gas, NH3 gas, H2O gas, H2O2 gas, and hydrocarbon gases (CH4 gas, C3H6 gas, etc.). The fluorine source may be a fluorine-containing gas that does not contain carbon, such as NF3 gas, SF6 gas, WF6 gas, or XeF2 gas. Alternatively, the fluorine source may be a fluorine-containing gas that contains carbon, such as fluorocarbon gas and hydrofluorocarbon gas. The fluorocarbon gas may be at least one selected from the group consisting of, for example, CF4 gas, C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 gas. The hydrofluorocarbon gas may be, for example, at least one selected from the group consisting of CHF3 gas, CH2F2 gas, CH3F gas, C2HF5 gas, and hydrofluorocarbon gases containing three or more C atoms (such as C3H2F4 gas, C3H2F6 gas, C4H2F6 gas, etc.).

[0067] In one embodiment, the processing gas (first processing gas or second processing gas) may further contain a phosphorus-containing gas. The phosphorus-containing gas may be, for example, a phosphorus halogenated gas. The phosphorus halogenated gas may be, for example, a phosphorus fluoride gas containing fluorine as a halogen element, such as PF3 gas or PF5 gas. The phosphorus halogenated gas may be, for example, a phosphorus chloride gas containing chlorine as a halogen element, such as PCl3 gas or PCl5 gas. The phosphorus halogenated gas may also be a gas containing bromine or iodine as halogen elements, such as PBr3 gas, PBr5 gas, or PI3 gas. The phosphorus halogenated gas may also be a gas containing two or more halogen elements, such as PClF2 gas, PCl2F gas, or PCl2F3 gas. The phosphorus halogenated gas may be, for example, an oxyphosphorus fluoride gas or an oxyphosphorus chloride gas. The phosphorus halogenated gas may be, for example, POF3 gas, POCl3 gas, POF2Cl2 gas, POFCl2 gas, or POF2Cl gas.

[0068] In one embodiment, the processing gas (first processing gas or second processing gas) may further contain a metal-containing gas. 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. Examples of metal-containing gases include WF2 gas, WF4 gas, WF5 gas, WF6 gas, WCl2 gas, WCl4 gas, WCl5 gas, WCl6 gas, MoF4 gas, MoF6 gas, MoCl6 gas, TiCl4 gas, etc. In one embodiment, the flow rate of the metal-containing gas may be 5 volume% or less of the total flow rate of the processing gas.

[0069] In one embodiment, the processing gas (first processing gas or second processing gas) may further contain halogen-containing gases other than fluorine. Examples of halogen-containing gases other than fluorine include chlorine-containing gases, bromine-containing gases, and / or iodine-containing gases. In one example, the chlorine-containing gas is at least one gas selected from the group consisting of Cl2, SiCl2, SiCl4, CCl4, SiH2Cl2, Si2Cl6, CHCl3, SO2Cl2, BCl3, PCl3, PCl5, and POCl3. In one example, the bromine-containing gas is at least one gas selected from the group consisting of Br2, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, and BBr3. In one example, the iodine-containing gas is at least one gas selected from the group consisting of HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3. In one example, the halogen-containing gas other than fluorine may be at least one selected from the group consisting of Cl2 gas, Br2 gas, and HBr gas. In another example, the halogen-containing gas other than fluorine is either Cl2 gas or HBr gas.

[0070] In one embodiment, the process gas (first process gas or second process gas) may further contain an oxygen-containing gas. The oxygen-containing gas may be, for example, at least one gas selected from the group consisting of O2, CO, CO2, H2O, and H2O2. In one example, the oxygen-containing gas may be an oxygen-containing gas other than H2O, for example, at least one gas selected from the group consisting of O2, CO, CO2, and H2O2. The flow rate of the oxygen-containing gas may be adjusted according to the flow rate of other gases (e.g., carbon-containing gas) contained in the process gas.

[0071] In one embodiment, the processing gas (first processing gas or second processing gas) may further contain a carbon-free fluorine-containing gas such as NF3 gas, SF6 gas, WF6 gas, or XeF2 gas.

[0072] In one embodiment, the processing gas (first processing gas or second processing gas) may include a carbon-containing gas. The carbon-containing gas includes at least one selected from the group consisting of CF-based gases (fluorocarbon gases), CHF-based gases (hydrofluorocarbon gases), and CH-based gases (hydrocarbon gases). For example, the CF-based gas may be at least one selected from the group consisting of CF4 gas, C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 gas. For example, the CHF-based gas may be at least one selected from the group consisting of CHF3 gas, CH2F2 gas, CH3F gas, C2HF5 gas, and hydrofluorocarbon gases containing three or more C atoms (e.g., C3H2F4 gas, C3H2F6 gas, C4H2F6 gas).

[0073] In one embodiment, the processing gas (first processing gas or second processing gas) may further contain an inert gas. For example, the inert gas may be a noble gas such as Ar gas, He gas, Kr gas, or N2 gas.

[0074] Figures 6A to 6D show examples of the cross-sectional structure of the substrate W during processing in step ST2. Figure 6A shows an example of the cross-sectional structure of the substrate W at the end of period T1 shown in Figures 5A to 5C. Similarly, Figures 6B to 6D show examples of the cross-sectional structure of the substrate W at the end of periods T2 to T4, respectively.

[0075] As shown in Figure 6A, during the process in period T1 (process ST21 of the Nth cycle, where N is a natural number), the portion of the silicon-containing film SF exposed at the opening OP is etched in the depth direction (from top to bottom in Figure 5A). This forms the recess RC. The silicon-containing film SF is etched by plasma generated from the first processing gas. At this time, a protective film PF containing bromine is formed on the sidewall of the silicon-containing film SF that defines the recess RC (hereinafter also referred to as the "sidewall of the recess RC"). The protective film PF is thought to be formed when bromine in the plasma generated from the first processing gas adheres to and deposits on the sidewall of the recess RC. The protective film PF may be formed on at least a part of the sidewall of the recess RC. The protective film PF may also be formed on the sidewall of the mask MK or on at least a part of the recess RC. The protective film PF may contain by-products from etching.

[0076] The protective film PF has low reactivity with HF species in the plasma and provides protection to the silicon-containing film SF. This suppresses lateral etching (left-right direction in Figure 6) of the sidewalls of the recessed RC, which can cause bowing. Bowing is one of the shape abnormalities of etching.

[0077] As shown in Figure 6B, the silicon-containing film SF is further etched in the depth direction by the treatment in period T2 (process ST22 of the Nth cycle). This increases the depth of the recessed area RC. Here, the chlorine in the plasma generated from the second treatment gas tends to contribute less to the formation of the protective film PF than the bromine in the plasma generated from the first treatment gas. Therefore, the protective film PF in the recessed area RC is gradually removed during period T2. If the protective film PF is excessively deposited in the recessed area RC, etching may not proceed in the vertical direction, potentially causing twisting and warping. In this regard, the treatment in period T2 can suppress the excessive deposition of the protective film PF on the side walls and bottom of the recessed area RC. As a result, twisting and warping can be suppressed. Twisting and warping are one of the shape abnormalities of etching. Furthermore, if the silicon-containing film contains nitrogen or the treatment gas contains nitrogen, ammonium silicate fluoride (AFS) may be generated as a by-product of etching and adhere to the side walls of the recessed area RC. If AFS is excessively deposited in the recessed area RC, etching may not proceed in the vertical direction, potentially causing twisting and warping. Here, the chlorine in the plasma generated from the second processing gas can suppress the generation of AFS. Therefore, even if the silicon-containing film contains nitrogen or the processing gas contains nitrogen, twisting and warping can be suppressed.

[0078] As shown in Figure 6C, the silicon-containing film SF is further etched in the depth direction during the process in period T3 (process ST21 of the N+1 cycle), increasing the depth of the recessed area RC. Also, similar to period T1 (process ST21 of the N+1 cycle), a protective film PF is formed again on the silicon-containing film SF. As described above, the protective film PF provides protection to the silicon-containing film SF and can suppress the occurrence of bowing in the silicon-containing film SF.

[0079] As shown in Figure 6D, the silicon-containing film SF is further etched in the depth direction by the processing in period T4 (process ST22 of the N+1 cycle), increasing the depth of the recessed area RC. Then, similar to period T2 (process ST22 of the 1st cycle), at the end of period T4 (process ST22), part or all of the protective film PF is removed. Note that Figure 6D shows an example where the bottom BT reaches the base film UF at the end of period T4, but it is not limited to this, and the bottom BT may reach the base film UF in subsequent cycles. The aspect ratio of the recessed area RC when the bottom BT has reached the base film UF may be, for example, 20 or more, and may be 30 or more, 40 or more, 50 or more, or 100 or more.

[0080] This processing method repeats a cycle including steps ST21 and ST22 until it is determined that the stop condition is met in step ST23. In step ST21 (periods T1 and T3), a protective film PF is formed, which can suppress bowing. In step ST22 (periods T2 and T4), part or all of the protective film PF formed in step ST21 is removed, which can suppress twisting and warping. Thus, this processing method allows etching to be performed in a balanced manner by alternately repeating the formation (step ST21) and removal (step ST22) of the protective film PF on the side walls of the recessed RC. This can suppress both shape deterioration due to bowing and shape deterioration due to twisting and warping in the recessed RC.

[0081] <Examples> Next, examples of this processing method will be described. This disclosure is not limited in any way by the following examples.

[0082] (Examples) In Examples 1 and 2, the processing method was applied using the plasma processing apparatus 1 to etch a substrate having a structure similar to the substrate W shown in Figure 4. An amorphous carbon film was used as the mask MK. A laminated film was used as the silicon-containing film SF, in which silicon nitride films and silicon oxide films were alternately and repeatedly stacked. The first processing gas used in step ST21 contained HF gas and HBr gas. The second processing gas used in step ST22 contained HF gas and Cl2 gas. In Example 1, the cycle of step ST21 (30 seconds) and step ST22 (30 seconds) was repeated 15 times, and etching was performed for a total of 15 minutes. The gas flow rate ratio in each step is shown in Figure 7. The gas flow rate ratio is normalized by the Cl2 gas flow rate in step ST21 of the example. The HF gas flow rate is the same in steps ST21 and ST22. Example 2 is the same as Example 1 except that the etching process was performed in the order of step ST22, then step ST21.

[0083] (Reference example) In the reference example, a substrate with the same configuration as in Examples 1 and 2 was etched using plasma processing apparatus 1. In the reference example, etching was performed for 15 minutes using a gas containing HBr gas and Cl2 gas. The gas flow rate ratio at this time is shown in Figure 7. The reference example was processed under the same conditions as in Example 1 or the other examples, except that the gas flow rate ratio was kept constant.

[0084] Figure 7 shows the bowing (maximum aperture width): B and line edge roughness: LER of the silicon-containing film SF after etching, according to the examples and reference examples. Note that each data is normalized using the data from the reference example.

[0085] The Boeing in Examples 1, 2, and the Reference Example is maintained at roughly the same level, but the LER in Examples 1 and 2 is significantly improved compared to the Reference Example. As discussed below, this is presumed to be because the deterioration of the shape in the recessed RC was suppressed, which in turn suppressed pattern distortion, resulting in an improvement in LER.

[0086] Therefore, the results in Figure 7 show that this processing method balances the protection of the silicon-containing film SF with the suppression of AFS generation by alternately repeating the formation (step ST21) and removal (step ST22) of the protective film PF, thereby suppressing shape deterioration during etching.

[0087] <Variation> Embodiments of this disclosure can be modified in various ways without departing from the scope and spirit of this disclosure.

[0088] For example, Figure 5A shows an example where the HF gas flow rate is constant throughout process ST2, but this is not the only example. In one example, the HF gas flow rate may differ between process ST21 (periods T1, T3, etc.) and process ST22 (periods T2, T4, etc.). The HF gas flow rate may also be changed from cycle to cycle; for example, one cycle (periods T1, T2) may have a different flow rate than another cycle (periods T3, T4). For example, the HF gas flow rate may be changed during each etching step in process ST21 or ST22. In one example, the HF gas flow rate may be gradually or stepwise increased or decreased during period T1 (the same applies to periods T2, T3, T4, etc.). If the first or second processing gas contains phosphorus-containing gas or other gases, the flow rate of these other gases does not have to be constant throughout process ST2, and may be changed as appropriate, as described above.

[0089] Furthermore, for example, this processing method may be carried out using a plasma processing apparatus that uses any plasma source other than the capacitively coupled plasma processing apparatus 1, such as an inductively coupled plasma or microwave plasma.

[0090] This disclosure may include, for example, the following configurations:

[0091] (Note 1) (a) Providing a substrate in a chamber, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, the mask including at least one opening, (b) Etching the silicon-containing film to form a recess, The above (b) is, (b1) Etching the silicon-containing film with plasma generated from a first processing gas, wherein the first processing gas includes hydrogen fluoride gas and bromine-containing gas, (b2) An etching method comprising etching the silicon-containing film with plasma generated from a second processing gas, wherein the second processing gas includes hydrogen fluoride gas and chlorine-containing gas.

[0092] (Note 2) The silicon-containing film is an etching method according to Appendix 1, wherein the film contains nitrogen.

[0093] (Note 3) The etching method according to any one of the appendices 1-2, wherein at least one of the first processing gas and the second processing gas contains a nitrogen-containing gas.

[0094] (Note 4) The etching method according to any one of the appendices 1-3, wherein (b1) comprises forming a protective film containing bromine on the side wall of the recess.

[0095] (Note 5) The etching method according to any one of the appendices 1-4, wherein (b2) includes removing reaction products adhering to the side wall of the recess.

[0096] (Note 6) The etching method described in any one of the appendices 1-5, wherein (b2) includes widening the opening dimensions of the bottom surface of the recess.

[0097] (Note 7) The etching method described in any one of the appendices 1-6, wherein the first processing gas does not contain chlorine-containing gas, or contains chlorine-containing gas at a flow rate ratio smaller than that of the chlorine-containing gas contained in the second processing gas.

[0098] (Note 8) The etching method according to any one of the appendices 1-7, wherein the second processing gas does not contain bromine-containing gas, or contains bromine-containing gas at a flow rate ratio smaller than that of the bromine-containing gas contained in the first processing gas.

[0099] (Note 9) The etching method described in any one of the appendices 1-8, wherein (b) comprises repeating a cycle including (b1) and (b2) multiple times.

[0100] (Note 10) The etching method according to any one of the appendices 1 to 9, wherein the ratio of the processing time of (b2) to the processing time of (b1) is changed according to the aspect ratio of the recess.

[0101] (Note 11) The etching method according to any one of the appendices 1-10, wherein the bromine-containing gas is at least one gas selected from the group consisting of Br2, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, and BBr3.

[0102] (Note 12) The etching method described in any one of the appendices 1-11, wherein the chlorine-containing gas is at least one gas selected from the group consisting of Cl2, SiCl2, SiCl4, CCl4, SiH2Cl2, Si2Cl6, CHCl3, SO2Cl2, BCl3, PCl3, PCl5, and POCl3.

[0103] (Note 13) In (a) above, the substrate is placed on the substrate support portion within the chamber, The etching method described in any one of the appendices 1-12, wherein the temperature of the substrate or the substrate support is controlled to be 0°C or lower.

[0104] (Note 14) The etching method according to any one of the appendices 1-13, wherein the first or second processing gas further comprises at least one gas selected from the group consisting of phosphorus-containing gases, metal-containing gases, carbon-containing gases, carbon-free fluorine-containing gases, and inert gases.

[0105] (Note 15) The etching method according to any one of the appendices 1-14, wherein the mask comprises at least one film selected from the group consisting of carbon-containing films and metal-containing films.

[0106] (Note 16) A plasma processing apparatus comprising a chamber, a substrate support portion within the chamber, a plasma generation portion, and a control portion, The control unit, (a) A substrate having a silicon-containing film and a mask on the silicon-containing film is provided on the substrate support portion in the chamber, wherein the mask includes at least one opening. (b) The system is configured to perform the following: etching the silicon-containing film on the substrate on the substrate support portion to form a recess, The above (b) is, (b1) Etching the silicon-containing film by generating plasma from a second processing gas containing bromine gas using the plasma generation unit, (b2) Etching the silicon-containing film by generating a plasma from a first processing gas containing a chlorine gas using the plasma generation unit, Plasma processing equipment.

[0107] In the exemplary embodiments described above, the etching method and the substrate processing apparatus can be modified in various ways without departing from the scope and spirit of the disclosure. For example, some components of one embodiment can be added to other embodiments within the ordinary ability of a person skilled in the art. Also, some components of one embodiment can be replaced with corresponding components of other embodiments. [Explanation of Symbols]

[0108] 1...Plasma processing apparatus, 2...Control unit, 10...Plasma processing chamber, 11...Substrate support unit, 12...Plasma generation unit, W...Substrate, SiF...Silicon-containing film, MK...Mask, OP1...Opening, S1...Side wall, R1...Recess

Claims

1. (a) Providing a substrate in a chamber, wherein the substrate comprises a silicon-containing film and a mask on the silicon-containing film, and the mask includes at least one opening. (b) Etching the silicon-containing film to form a recess, The above (b) is, (b1) Etching the silicon-containing film with plasma generated from a first processing gas, wherein the first processing gas includes hydrogen fluoride gas and bromine-containing gas, (b) Etching the silicon-containing film with plasma generated from a second processing gas, wherein the second processing gas includes hydrogen fluoride gas and chlorine-containing gas.

2. The etching method according to claim 1, wherein the silicon-containing film contains nitrogen.

3. The etching method according to claim 1, wherein at least one of the first processing gas and the second processing gas contains a nitrogen-containing gas.

4. The etching method according to claim 2 or 3, wherein (b1) comprises forming a protective film containing bromine on the side wall of the recess.

5. The etching method according to claim 2 or 3, wherein (b2) includes removing reaction products adhering to the side wall of the recess.

6. The etching method according to claim 2 or 3, wherein (b2) includes widening the opening dimensions of the bottom surface of the recess.

7. The etching method according to claim 1, wherein the first processing gas does not contain a chlorine-containing gas, or contains a chlorine-containing gas at a flow rate ratio smaller than that of the chlorine-containing gas contained in the second processing gas.

8. The etching method according to claim 1, wherein the second processing gas does not contain bromine-containing gas, or contains bromine-containing gas at a flow rate ratio smaller than that of the bromine-containing gas contained in the first processing gas.

9. The etching method according to claim 1, wherein (b) comprises repeating a cycle including (b1) and (b2) multiple times.

10. The etching method according to claim 9, wherein the ratio of the processing time of (b2) to the processing time of (b1) is changed according to the aspect ratio of the recess.

11. The bromine-containing gas is Br 2 , HBr, CBr 2 F 2 , C 2 F 5 Br, PBr 3 , PBr 5 , POBr 3 and BBr 3 is at least one gas selected from the group consisting of, The etching method according to claim 1.

12. The chlorine-containing gas is Cl 2 SiCl 2 SiCl 4 , CCl 4 SiH 2 Cl 2 Si 2 Cl 6 , CHCl 3 SO 2 Cl 2 , BCl 3 , PCL 3 , PCL 5 and POCl 3 The etching method according to claim 1, wherein the gas is at least one gas selected from the group consisting of the following.

13. In (a) above, the substrate is placed on the substrate support portion within the chamber, The etching method according to claim 1, wherein in (b) above, the temperature of the substrate or the substrate support is controlled to be 0°C or lower.

14. The etching method according to claim 1, wherein the first processing gas or the second processing gas further comprises at least one gas selected from the group consisting of phosphorus-containing gases, metal-containing gases, carbon-containing gases, carbon-free fluorine-containing gases, and inert gases.

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

16. A plasma processing apparatus comprising a chamber, a substrate support portion within the chamber, a plasma generation portion, and a control portion, The control unit, (a) A substrate having a silicon-containing film and a mask on the silicon-containing film is provided on the substrate support portion in the chamber, wherein the mask includes at least one opening. (b) The system is configured to perform the following: etching the silicon-containing film on the substrate on the substrate support portion to form a recess, The above (b) is, (b1) Etching the silicon-containing film by generating plasma from a second processing gas containing bromine gas using the plasma generation unit, (b2) Etching the silicon-containing film by generating plasma from a first processing gas containing chlorine gas using the plasma generation unit, Plasma processing equipment.

Images