Etching method and plasma processing system

Abstract

To keep down abnormalities in geometry of etching.SOLUTION: Provided is an etching method. The method comprises the steps of: (a)providing a substrate having a silicon-containing film containing silicon and nitrogen and a mask on the silicon-containing film to a substrate support part in a chamber; (b)supplying inside of the chamber with a process gas that contains a hydrogen fluoride gas and a chlorine-containing gas, in which a flow rate of the chlorine-containing gas is equal to or larger than 1.5 vol.% of a total flow rate of a process gas excluding an inactive gas; and (c)generating plasma from the process gas to etch the silicon-containing film.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Patent Documents 1 and 2 disclose techniques for etching silicon-containing films.

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 for suppressing abnormal etching shapes.

Means for Solving the Problems

[0005] In one exemplary embodiment of the present disclosure, there is provided an etching method including: (a) providing a substrate having a silicon-containing film containing silicon and nitrogen and a mask on the silicon-containing film on a substrate support in a chamber; (b) supplying a processing gas containing hydrogen fluoride gas and a chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5% by volume or more of the total flow rate of the processing gas excluding the inert gas; and (c) generating plasma from the processing gas to etch the silicon-containing film.

Effects of the Invention

[0006] According to one exemplary embodiment of the present disclosure, a technique for suppressing abnormal etching shapes can be provided. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram illustrating an exemplary plasma processing system. [Figure 2] This flowchart shows an example of this processing method. [Figure 3] This figure shows an example of the cross-sectional structure of substrate W. [Figure 4] This figure shows an example of the cross-sectional structure of the substrate W during processing in step ST3. [Figure 5] This figure shows the etching results according to the examples and reference examples. [Figure 6] This figure shows the etching results according to the examples and reference examples. [Modes for carrying out the invention]

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

[0009] In one exemplary embodiment, an etching method is provided which includes the steps of: (a) providing a substrate having a silicon-containing film containing silicon and nitrogen, and a mask on the silicon-containing film, on a substrate support in a chamber; (b) supplying a processing gas containing hydrogen fluoride gas and chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5 volume% or more of the total flow rate of the processing gas excluding the inert gas; and (c) generating plasma from the processing gas to etch the silicon-containing film.

[0010] In one exemplary embodiment, the chlorine-containing gas includes phosphorus chloride gas.

[0011] In one exemplary embodiment, the chlorine-containing gas includes at least one selected from the group consisting of PCl3 gas, PCl5 gas, and POCl3 gas.

[0012] In one exemplary embodiment, the chlorine-containing gas contains at least one selected from the group consisting of Cl2 gas, HCl gas, SiCl2 gas, and BCl3 gas.

[0013] In one exemplary embodiment, the processing gas further contains phosphorus fluoride gas.

[0014] In one exemplary embodiment, the phosphorus fluoride gas is at least one of PF3 gas and PF5 gas.

[0015] In one exemplary embodiment, the flow rate of the chlorine-containing gas is 5% by volume or less of the total flow rate of the processing gas excluding the inert gas.

[0016] In one exemplary embodiment, the chlorine-containing gas contains carbon.

[0017] In one exemplary embodiment, the chlorine-containing gas contains a gas of CxHyFzClw (where x and w are integers of 1 or more, and y and z are integers of 0 or more).

[0018] In one exemplary embodiment, the processing gas further contains a phosphorus-containing gas.

[0019] In one exemplary embodiment, excluding the inert gas, the processing gas has the highest flow rate of hydrogen fluoride gas.

[0020] In one exemplary embodiment, the processing gas further contains a carbon-containing gas.

[0021] In one exemplary embodiment, the carbon-containing gas is either a fluorocarbon gas or a hydrofluorocarbon gas.

[0022] In one exemplary embodiment, the processing gas further contains at least one of an oxygen-containing gas and a metal-containing gas.

[0023] In one exemplary embodiment, the silicon-containing film further comprises a silicon nitride film and at least one of a silicon oxide film and a polysilicon film.

[0024] In one exemplary embodiment, the mask is a carbon-containing film or a metal-containing film.

[0025] In one exemplary embodiment, in step (c), the temperature of the substrate support is set to 0°C or lower.

[0026] In one exemplary embodiment, an etching method is provided which includes the steps of: (a) providing a substrate having a silicon-containing film containing silicon and nitrogen, and a mask on the silicon-containing film, on a substrate support in a chamber; (b) supplying a processing gas containing a single gas or mixed gas containing fluorine and hydrogen and a chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5 volume% or more of the total flow rate of the processing gas excluding the inert gas; and (c) generating plasma from the processing gas to etch the silicon-containing film, wherein the plasma contains an active species of hydrogen fluoride.

[0027] In one exemplary embodiment, the single gas or mixed gas containing fluorine and hydrogen is at least one selected from the group consisting of hydrogen fluoride gas, hydrofluorocarbon gas, and mixed gases containing a fluorine-containing gas and a hydrogen-containing gas.

[0028] In one exemplary embodiment, a plasma processing system is provided comprising a chamber, a substrate support section provided within the chamber, a plasma generation section, and a control section, wherein the control section performs the following: (a) control of providing a substrate having a silicon-containing film containing silicon and nitrogen and a mask on the silicon-containing film onto the substrate support section in the chamber; (b) control of supplying a processing gas containing hydrogen fluoride gas and chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5 volume% or more of the total flow rate of the processing gas excluding the inert gas; and (c) control of generating plasma from the processing gas and etching the silicon-containing film.

[0029] 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.

[0030] <Example of a plasma processing system configuration> The following describes an example of a plasma processing system configuration. Figure 1 is a diagram illustrating an example of a capacitively coupled plasma processing system configuration.

[0031] The plasma processing system includes a capacitively coupled plasma processing apparatus 1 and a control unit 2. The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. 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 has at least one gas supply port for supplying at least one processing gas to the plasma processing space 10s and at least one gas outlet for discharging gas from the plasma processing space. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support part 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0032] 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 the 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.

[0033] 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 electrode 1111b placed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may also 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. Furthermore, at least one RF / DC electrode, coupled to the RF (Radio Frequency) power supply 31 and / or DC (Direct Current) power supply 32 described later, may be placed within the ceramic member 1111a. In this case, at least one RF / DC electrode functions as a lower electrode. When a bias RF signal and / or DC signal, described later, is supplied to at least one RF / DC electrode, the RF / DC electrode is also called a bias electrode. Note that the conductive member of the base 1110 and at least one RF / DC electrode may function as multiple lower electrodes. Also, the electrostatic electrode 1111b may function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] 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 one or more flow modulation devices that modulate or pulse the flow rate of at least one processing gas.

[0038] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and / or at least one upper electrode. This causes plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power supply 31 can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. 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.

[0039] In one embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF 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.

[0040] The second RF generation unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 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. One or more generated 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.

[0041] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generation unit 32a and a second DC generation unit 32b. In one embodiment, the first DC generation unit 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to at least one lower electrode. In one embodiment, the second DC generation unit 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to at least one upper electrode.

[0042] In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof pulse waveform. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from a DC signal is connected between the first DC generation unit 32a and at least one lower electrode. Thus, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. When the second DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses may have positive 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 DC generation units 32a and 32b may be provided in addition to the RF power supply 31, and the first DC generation unit 32a may be provided in place of the second RF generation unit 31b.

[0043] 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.

[0044] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform 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, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or it may be obtained via a medium when needed. The obtained 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 processing unit 2a1 may be a CPU (Central Processing Unit). 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).

[0045] <An example of etching method> Figure 2 is a flowchart showing an example of an etching method (hereinafter also referred to as "this processing method") according to one exemplary embodiment. As shown in Figure 2, this processing method includes a step ST1 of providing a substrate, a step ST2 of supplying a processing gas, and a step ST3 of etching. The processing in each step 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 to perform this processing method on the substrate W will be described as an example.

[0046] (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 portion 11. The substrate W is then held in the substrate support portion 11 by an electrostatic chuck 1111.

[0047] Figure 3 shows an example of the cross-sectional structure of a substrate W. The substrate W consists of a silicon-containing film SF and a mask MF stacked 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, semiconductor memory devices such as DRAM and 3D-NAND flash memory.

[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] The silicon-containing film SF is the film to be etched in this processing method. The silicon-containing film SF includes a film containing silicon and nitrogen. The film containing silicon and nitrogen may be a silicon nitride film or a silicon dioxide film. In addition to silicon and nitrogen, the film containing silicon and nitrogen may be a film doped with impurities such as phosphorus, boron, or nitrogen. The silicon-containing film SF may further include other silicon-containing films in addition to the film containing silicon and nitrogen, such as a film containing silicon and oxygen, a film containing polycrystalline silicon, or a film containing silicon and carbon. The silicon-containing film SF may be a multilayer film including a silicon nitride film and at least one of a silicon oxide film and a polycrystalline silicon film. For example, the silicon-containing film SF may be a multilayer film in which silicon oxide films and silicon nitride films are alternately layered. Alternatively, for example, the silicon-containing film SF may be a multilayer film including a silicon nitride film, a silicon oxide film, and a polycrystalline silicon film. In this case, the silicon nitride film, silicon oxide film, or polycrystalline silicon film may be a film doped with impurities such as phosphorus, boron, or nitrogen.

[0050] Mask MF is a film that functions as a mask in etching the silicon-containing film SF. Mask MF may be a carbon-containing film such as an amorphous carbon film, a photoresist film, or a SOC film. Mask MF may also be a silicon-containing film such as a silicon-containing anti-reflective film. Mask MF may also be a metal-containing film such as tungsten, titanium nitride, tungsten carbide, or tungsten silicide.

[0051] As shown in Figure 3, the mask MF 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 sidewalls of the mask MF. That is, the upper surface of the silicon-containing film SF has a region covered by the mask MF and a region exposed at the bottom of the opening OP.

[0052] 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 3. 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 MF 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.

[0053] Each film constituting the substrate W (underlayment film UF, silicon-containing film SF, mask MF) may be formed by CVD, ALD, spin coating, etc. The opening OP may be formed by etching the mask MF. The mask MF may also be formed by lithography. Each of the above films may be flat or may have irregularities. The substrate W may also have other films beneath the underlayment film UF, and the laminated film of silicon-containing film SF and underlayment film UF may function as a multilayer mask. That is, the laminated film of silicon-containing film SF and underlayment film UF may be used as a multilayer mask to etch the other films.

[0054] 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 MF to form an aperture OP may be performed in the plasma processing chamber 10. That is, the etching of the aperture 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.

[0055] 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, 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, 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 a 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 subsequent steps after step ST1, the temperature of the substrate support 11 may be maintained at the set temperature adjusted in step ST1.

[0056] (Process ST2: Supply of processing gas) In step ST2, a processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The processing gas includes hydrogen fluoride (HF) gas and chlorine-containing gas. In one embodiment, the processing gas may further contain phosphorus fluoride gas. In one embodiment, the processing gas may not contain phosphorus fluoride gas.

[0057] The flow rate of the HF gas may be the highest in terms of flow rate (partial pressure) among the process gases (excluding the inert gas if the process gases include one). For example, the flow rate of the HF gas may be 50% or more, 60% or more, 70% or more, or even 80% or more of the total flow rate of the process gases (or the total flow rate of all gases excluding the inert gas if the process gases include one). High-purity HF gas, such as one with a purity of 99.999% or higher, may be used.

[0058] Phosphorus fluoride gas is a gas containing fluorine and phosphorus, and may be at least one selected from PF3 gas, PF5 gas, POF3 gas, HPF2 gas, H2PF3 gas, and HPF6 gas.

[0059] The chlorine-containing gas may be at least one selected from, for example, Cl2 gas, HCl gas, SiCl2 gas, BCl3 gas, and PCl3 gas. Alternatively, the chlorine-containing gas may be a gas containing chlorine and boron or phosphorus, for example, boron chloride gas such as BCl3 gas, or phosphorus chloride gas such as PCl3 gas. The flow rate of the chlorine-containing gas may be 1.5 volume% or more of the total flow rate of the treatment gas (or the total flow rate of all gases excluding the inert gas if the treatment gas contains an inert gas), or it may be 2 volume% or more.

[0060] In one embodiment, the chlorine-containing gas includes at least one selected from Cl2 gas, HCl gas, SiCl2 gas, and BCl3 gas. In this case, the flow rate of the chlorine-containing gas may be 5% by volume or less, or 4% by volume or less, of the total flow rate of the treatment gas (or the total flow rate of all gases excluding the inert gas if the treatment gas includes an inert gas).

[0061] In one embodiment, the chlorine-containing gas includes phosphorus chloride gas. The phosphorus chloride gas may be at least one selected from the group consisting of, for example, PCl3 gas, PCl5 gas, and POCl3 gas. In this case, the flow rate of the chlorine-containing gas may be 20% by volume or less, 15% by volume or less, or 10% by volume or less of the total flow rate of the treatment gas (or the total flow rate of all gases excluding the inert gas if the treatment gas includes an inert gas).

[0062] In one embodiment, the chlorine-containing gas contains carbon. The carbon-containing chlorine-containing gas may be, for example, a CxHyFzClw gas (where x and w are integers of 1 or more, and y and z are integers of 0 or more). Contains The gas may be, for example, CHCl3 gas or CH2Cl2 gas.

[0063] The processing gas may further contain a carbon-containing gas. The carbon-containing gas may be, for example, either or both of a fluorocarbon gas and a hydrofluorocarbon gas. In one example, the fluorocarbon gas may be at least one selected from the group consisting of C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas and C5F8 gas. In one example, the hydrofluorocarbon gas may be CHF3 gas, CH2F2 gas, CH3F gas, C2HF5 gas, C2H2F4 gas, C2H3F3 gas, C2H4F2 gas, C3HF7 gas, C3H2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, C5H2F 10At least one gas selected from the group consisting of gases and C5H3F7 gas may be used. The carbon-containing gas may also be a linear gas having unsaturated bonds. For example, at least one linear carbon-containing gas having unsaturated bonds may be used, selected from the group consisting of C3F6 (hexafluoropropene) gas, C4F8 (octafluoro-1-butene, octafluoro-2-butene) gas, C3H2F4 (1,3,3,3-tetrafluoropropene) gas, C4H2F6 (trans-1,1,1,4,4,4-hexafluoro-2-butene) gas, C4F8O (pentafluoroethyl trifluorovinyl ether) gas, CF3COF gas (1,2,2,2-tetrafluoroethane-1-one), CHF2COF (difluoroacetic acid fluoride) gas, and COF2 (carbonyl fluoride) gas. In addition, among the above carbon-containing gases, gases with 2 or more carbon atoms may be used.

[0064] The processing 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 the carbon-containing gas.

[0065] The processing gas may further contain a metal-containing gas. The metal-containing gas may be, for example, a tungsten-containing gas. The tungsten-containing gas may be a gas containing tungsten and a halogen, one example being WF a Cl bThe gas is a gas (where a and b are integers between 0 and 6, and the sum of a and b is between 2 and 6). The tungsten-containing gas may be, for example, a gas containing tungsten and fluorine, such as tungsten difluoride (WF2) gas, tungsten tetrafluoride (WF4) gas, tungsten pentafluoride (WF5) gas, tungsten hexafluoride (WF6) gas, or a gas containing tungsten and chlorine, such as tungsten dichloride (WCl2) gas, tungsten tetrachloride (WCl4) gas, tungsten pentachloride (WCl5) gas, or tungsten hexachloride (WCl6) gas. The tungsten-containing gas may be at least one of WF6 gas and WCl6 gas. As the metal-containing gas, at least one of titanium-containing gas or molybdenum-containing gas may be used in place of or in addition to the tungsten-containing gas.

[0066] The processing gas may further contain an inert gas. The inert gas may be, for example, a noble gas such as Ar gas, He gas, or Kr gas, or nitrogen gas.

[0067] The processing gas may include, in place of or in addition to HF gas, a gas capable of generating active species of hydrogen fluoride in the plasma. The active species of hydrogen fluoride includes at least one of hydrogen fluoride gas, radicals, and ions.

[0068] Gases capable of generating the active species of hydrogen fluoride include, 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.

[0069] Gases capable of generating active species of hydrogen fluoride include, for example, fluorine-containing gases and hydrogen-containing gases. Fluorine-containing gases include, for example, fluorocarbon gases. One example of a fluorocarbon gas is at least one selected from the group consisting of C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 gas. Alternatively, the fluorine-containing gas may be, for example, NF3 gas or SF6 gas. One example of a hydrogen-containing gas is at least one selected from the group consisting of H2 gas, CH4 gas, and NH3 gas.

[0070] (Step ST3: Etching) In step ST3, the silicon-containing film SF is etched using plasma generated from the processing gas. First, 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. This generates a high-frequency electric field between the shower head 13 and the substrate support 11, and plasma is generated from the processing gas in the plasma processing space 10s. At this time, a bias signal may be supplied to the lower electrode of the substrate support 11. In this case, a bias potential is generated between the plasma and the substrate W. Active species such as ions and radicals in the plasma are attracted to the substrate W, and the silicon-containing film SF is etched by these active species.

[0071] The bias signal supplied to the substrate support 11 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.

[0072] Figure 4 shows an example of the cross-sectional structure of the substrate W during processing in step ST3. As shown in Figure 4, the processing in step ST3 etches the portion of the silicon-containing film SF exposed at the opening OP in the depth direction (from top to bottom in Figure 4), forming a recess RC. The aspect ratio of the recess RC when it reaches the underlying 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.

[0073] In one embodiment, the process conditions may be changed during step ST3. Changing the process conditions includes, for example, changing the partial pressure of the chlorine-containing gas during step ST3. That is, in step ST3, after etching the silicon-containing film SF with the partial pressure of the chlorine-containing gas set to a first partial pressure, the partial pressure of the chlorine-containing gas may be changed to a second partial pressure different from the first partial pressure, and the silicon-containing film SF may be further etched.

[0074] If the processing gas contains phosphorus fluoride gas, the modification of process conditions may include, for example, changing the partial pressure of phosphorus fluoride gas during step ST3. That is, in step ST3, after etching the silicon-containing film SF with the partial pressure of phosphorus fluoride gas set to a third partial pressure, the partial pressure of phosphorus fluoride gas may be changed to a fourth partial pressure different from the third partial pressure to further etch the silicon-containing film SF.

[0075] Changing the process conditions includes, for example, changing the type of chlorine-containing gas during step ST3. That is, in step ST3, a plasma may be generated from hydrogen fluoride gas and a first chlorine-containing gas to etch the silicon-containing film, and then a plasma may be generated from hydrogen fluoride gas and a second chlorine-containing gas different from the first chlorine-containing gas to etch the silicon-containing film. In one example, the first chlorine-containing gas may be Cl2 gas, and the second chlorine-containing gas may be a chlorine-containing gas other than Cl2 gas, such as BCl3 gas.

[0076] Process conditions (partial pressure of chlorine-containing gas / partial pressure of phosphorus fluoride gas / type of chlorine-containing gas, etc.) may be changed, for example, by the aspect ratio of the recessed RC formed in process ST3, the depth of the recessed RC, or the processing time of process ST3. Furthermore, process conditions may be changed based on previously acquired data indicating the shape of the recessed RC or data indicating the shape of the recessed RC estimated from plasma emission intensity, etc.

[0077] As described above, the shape of the recess can be more appropriately controlled by changing the process conditions during step ST3.

[0078] In this processing method, the processing gas includes HF gas. Hydrogen fluoride in the plasma generated from the processing gas functions as an etchant for the silicon-containing film SF. When the processing gas includes phosphorus fluoride gas, the phosphorus derived from the phosphorus fluoride gas can promote the adsorption of hydrogen fluoride at the bottom of the recessed RC. This can improve the etching rate of the silicon-containing film SF.

[0079] Here, if the amount of hydrogen (H) and fluorine (F) derived from HF gas and phosphorus fluoride gas in the plasma increases, etching is promoted, but the amount of reaction byproducts may also increase. Reaction byproducts may include ammonium silicofluoride (NH4) 2SiF6 (hereinafter referred to as "AFS"), which is produced by the reaction of silicon nitride (SiN) in the silicon-containing film SF with hydrogen fluoride. AFS is not easily volatile and can adhere to recesses RC in the silicon-containing film SF, causing etching shape abnormalities. Such shape abnormalities may include tapering at the bottom of the recess RC, bending, and twisting of the recess RC.

[0080] In this processing method, the processing gas contains chlorine. The chlorine in the plasma reacts with AFS to produce highly volatile SiF4 and other substances, thus decomposing the AFS. In other words, the chlorine in the plasma can reduce the amount of AFS adhering to recessed RC and other surfaces, thereby suppressing etching abnormalities. On the other hand, if there is an excess of chlorine in the plasma, the mask MF will be etched, making it difficult to ensure a sufficient selectivity ratio for the mask MF. Furthermore, an excess of chlorine in the plasma can lower the partial pressure of hydrogen fluoride and phosphorus in the plasma, potentially reducing the etching rate of the silicon-containing film SF.

[0081] In this processing method, the flow rate of chlorine-containing gas is 1.5 volume% or more of the total flow rate of the processing gas (or the total flow rate of all gases excluding the inert gas if the processing gas includes an inert gas). If the flow rate of chlorine-containing gas is 1.5 volume% or more, the effect of suppressing the shape abnormalities of the recessed RC described above can be obtained. Furthermore, if the chlorine-containing gas includes phosphorus chloride gas (e.g., PCl3 gas, PCl5 gas, and POCl3 gas, etc.), if the flow rate of the chlorine-containing gas is 20 volume% or less, the reduction in etching rate and selectivity described above will not occur or will be limited. If the chlorine-containing gas does not contain phosphorus (e.g., Cl2 gas, HCl gas, SiCl2 gas, and BCl3 gas, etc.), if the flow rate of the chlorine-containing gas is 5 volume% or less, the reduction in etching rate and selectivity described above will not occur or will be limited.

[0082] This processing method suppresses the reduction in etching rate and selectivity of the silicon-containing film while also suppressing shape abnormalities in the recesses formed in the silicon-containing film.

[0083] <Examples> Next, examples of this processing method will be described. This disclosure is not limited in any way by the following examples.

[0084] (Examples 1 and 2) 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 3. An amorphous carbon film was used as the mask MF. 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 processing gas used in step ST2 contained HF gas, PF3 gas, and BCl3 gas. In Example 1, the processing gas contained 1.8 volume% of BCl3 gas relative to the total flow rate of the processing gas. In Example 2, the processing gas contained 2.7 volume% of BCl3 gas relative to the total flow rate of the processing gas. During etching, the temperature of the substrate support portion 11 was set to -70°C.

[0085] (Reference example 1) In Reference Example 1, a substrate with the same configuration as in Examples 1 and 2 was etched using plasma processing apparatus 1. Reference Example 1 was etched under the same conditions as in Examples 1 and 2, except that the processing gas did not contain BCl3 gas.

[0086] Figure 5 shows the etching results for the examples and reference examples. In Figure 5, the vertical axis represents the depth D [nm] of the recess formed in the silicon-containing film SF. The horizontal axis represents the displacement S [nm] of the recess RC. The displacement S is the distance between the midpoint of the width of the recess RC at a certain depth and the center reference line (a line passing through the midpoint of the width of the recess RC at zero depth). The displacement S increases as the bending and twisting of the recess RC formed in the silicon-containing film SF increases.

[0087] As shown in Figure 5, in Examples 1 and 2, the displacement amount S was kept significantly smaller than in Reference Example 1, even when the depth of the recess increased. In other words, the shape of the recess formed in Examples 1 and 2 was remarkably better than that of Reference Example 1. Although the etching rates of Examples 1 and 2 were lower than those of Reference Example 1, they were still sufficient, at 92% and 81% of the etching rate of Reference Example 1, respectively. The selectivity ratios of Examples 1 and 2 were also lower than those of Reference Example 1, at 81% and 71% of the selectivity ratio of Reference Example 1, respectively, and the mask MF after etching maintained sufficient thickness in both cases.

[0088] As described above, the etching of the silicon-containing film SF in Example 1 and Example 2 significantly suppressed the shape abnormalities during etching compared to Reference Example 1, while also suppressing the decrease in etching rate and selectivity.

[0089] (Example 3) In Example 3, 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 3. An amorphous carbon film was used as the mask MF. 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 processing gas used in step ST2 contained HF gas, PCl3 gas, and Ar gas. PCl3 gas was present at 10% of the total flow rate of the processing gas excluding the inert gas. During etching, the temperature of the substrate support portion 11 was set to -70°C.

[0090] (Reference example 2) In Reference Example 2, a substrate with the same configuration as in Examples 1 and 2 was etched using plasma processing apparatus 1. Reference Example 2 was etched under the same conditions as in Example 3, except that the processing gas contained PF3 gas instead of PCl3 gas. The PF3 gas was present at 10% of the total flow rate of the processing gas excluding the inert gas.

[0091] Figure 6 shows the etching results for the examples and reference examples. Figure 6 shows the shape of the recessed RC after etching for Example 3 and Reference Example 2. In Reference Example 2, twisting occurred at the bottom BT of the recessed RC. In contrast, in Example 3, no twisting occurred at the bottom BT of the recessed RC. That is, Example 3 was able to suppress etching shape abnormalities more effectively than Reference Example 2.

[0092] Embodiments of this disclosure further include the following embodiments:

[0093] (Note 1) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a silicon-containing film including a silicon nitride film and a mask on the silicon-containing film onto a substrate support portion in a chamber, (b) A step of supplying a treatment gas containing hydrogen fluoride gas, phosphorus fluoride gas, and chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5% by volume or more and 5% by volume or less of the total flow rate of the treatment gas excluding the inert gas, (c) A step of generating plasma from the processing gas and etching the silicon-containing film, Etching method.

[0094] (Note 2) The etching method according to Appendix 1, wherein the chlorine-containing gas is at least one selected from the group consisting of Cl2 gas, HCl gas, SiCl2 gas, BCl3 gas, and PCl3 gas.

[0095] (Note 3) The etching method described in Appendix 1, wherein the chlorine-containing gas is a gas containing chlorine and boron or phosphorus.

[0096] (Note 4) The etching method according to any one of claims 1 to 3, wherein the phosphorus fluoride gas is at least one of PF3 gas and PF5 gas.

[0097] (Note 5) The etching method according to any one of Appendix 1 to Appendix 4, wherein, excluding the inert gas, the flow rate of the hydrogen fluoride gas is the highest among the processing gases.

[0098] (Note 6) The etching method according to any one of Appendix 1 to Appendix 5, wherein the processing gas further comprises a carbon-containing gas.

[0099] (Note 7) The etching method according to Appendix 6, wherein the carbon-containing gas is either a fluorocarbon gas or a hydrofluorocarbon gas.

[0100] (Note 8) The etching method according to Appendix 7, wherein the carbon-containing gas has 2 or more carbon atoms.

[0101] (Note 9) The etching method according to any one of the appendices 1 to 8, wherein the processing gas further comprises at least one of an oxygen-containing gas and a metal-containing gas.

[0102] (Note 10) The etching method according to Appendix 9, wherein the oxygen-containing gas comprises at least one gas selected from the group consisting of O2, CO, CO2, H2O, and H2O2.

[0103] (Note 11) The etching method according to Appendix 9, wherein the metal-containing gas comprises at least one gas selected from the group consisting of tungsten-containing gas, titanium-containing gas, or molybdenum-containing gas.

[0104] (Note 12) The etching method according to any one of the appendices 1 to 11, wherein the processing gas further comprises an inert gas.

[0105] (Note 13) The etching method according to any one of Appendix 1 to Appendix 12, wherein the silicon-containing film further comprises at least one of a silicon oxide film and a polysilicon film.

[0106] (Note 14) The etching method according to any one of Appendix 1 to Appendix 13, wherein the mask is a carbon-containing film or a metal-containing film.

[0107] (Note 15) An etching method according to any one of Appendix 1 to Appendix 14, wherein in step (c) above, the temperature of the substrate support portion is set to 0°C or lower.

[0108] (Note 16) An etching method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a silicon-containing film containing at least a silicon nitride film and a mask on the silicon-containing film onto a substrate support portion in a chamber, (b) A step of supplying a processing gas containing at least phosphorus fluoride gas and chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5% by volume or more and 5% by volume or less of the total flow rate of the processing gas excluding the inert gas, (c) A step of generating plasma from the processing gas and etching the silicon-containing film, wherein the plasma includes an active species of hydrogen fluoride. Etching method.

[0109] (Note 17) The etching method according to Appendix 16, wherein the active species of hydrogen fluoride is generated from at least one of the following gases in the processing gas: hydrogen fluoride gas or hydrofluorocarbon gas.

[0110] (Note 18) The etching method according to Appendix 16, wherein the active species of hydrogen fluoride is generated from a hydrofluorocarbon gas having two or more carbon atoms in the processing gas.

[0111] (Note 19) The etching method described in Appendix 16, wherein the active species of hydrogen fluoride is generated from the fluorine-containing gas and hydrogen-containing gas in the processing gas.

[0112] (Note 20) A plasma processing system comprising a chamber, a substrate support section provided within the chamber, a plasma generation section, and a control section, The control unit, (a) Control to provide a substrate having a silicon-containing film containing at least a silicon nitride film and a mask on the silicon-containing film onto a substrate support portion in a chamber, (b) A control for supplying a treatment gas containing hydrogen fluoride gas, phosphorus fluoride gas, and chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5% by volume or more and 5% by volume or less of the total flow rate of the treatment gas excluding the inert gas, (c) Control to generate plasma from the processing gas and etch the silicon-containing film. Plasma processing system.

[0113] (Note 21) A device manufacturing method performed in a plasma processing apparatus having a chamber, (a) A step of providing a substrate having a silicon-containing film including a silicon nitride film and a mask on the silicon-containing film onto a substrate support portion in a chamber, (b) A step of supplying a treatment gas containing hydrogen fluoride gas, phosphorus fluoride gas, and chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5% by volume or more and 5% by volume or less of the total flow rate of the treatment gas excluding the inert gas, (c) A step of generating plasma from the processing gas and etching the silicon-containing film, Device manufacturing method.

[0114] (Note 22) A computer in a plasma processing system comprising a chamber, a substrate support section provided within the chamber, and a plasma generation section, (a) Control to provide a substrate having a silicon-containing film containing at least a silicon nitride film and a mask on the silicon-containing film onto a substrate support portion in a chamber, (b) A control for supplying a treatment gas containing hydrogen fluoride gas, phosphorus fluoride gas, and chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5% by volume or more and 5% by volume or less of the total flow rate of the treatment gas excluding the inert gas, (c) Control to generate plasma from the processing gas and etch the silicon-containing film. program.

[0115] (Note 23) A storage medium containing the program described in Appendix 22.

[0116] (Note 24) (a) A step of providing a substrate having a silicon-containing film containing silicon and nitrogen, and a mask on the silicon-containing film, onto a substrate support portion in a chamber, (b) A step of supplying a treatment gas containing hydrogen fluoride gas and chlorine-containing gas into the chamber, wherein the flow rate of the chlorine-containing gas is 1.5 volume percent or more of the total flow rate of the treatment gas excluding the inert gas, (c) An etching method comprising the step of generating plasma from the processing gas and etching the silicon-containing film.

[0117] (Note 25) The above (c) is, The process involves setting the partial pressure of the chlorine-containing gas to a first partial pressure and etching the silicon-containing film, A step of etching the silicon-containing film by setting the partial pressure of the chlorine-containing gas to a second partial pressure different from the first partial pressure, The etching method described in Appendix 25, including the method described therein.

[0118] (Note 26) The etching method according to Appendix 24 or Appendix 25, wherein the processing gas further comprises phosphorus fluoride gas.

[0119] (Note 27) The above (c) is, The process involves setting the partial pressure of the phosphorus fluoride gas to a third partial pressure and etching the silicon-containing film, The process involves setting the partial pressure of the phosphorus fluoride gas to a fourth partial pressure different from the third partial pressure, and etching the silicon-containing film. The etching method described in Appendix 26, including the method described in Appendix 26.

[0120] (Note 28) The above (c) is, A step of generating plasma from the hydrogen fluoride gas and the first chlorine-containing gas to etch the silicon-containing film, A step of generating plasma from the hydrogen fluoride gas and a second chlorine-containing gas different from the first chlorine-containing gas, to etch the silicon-containing film, An etching method as described in any one of Appendix 24 to Appendix 27, including the above.

[0121] Embodiments of this disclosure can be modified in various ways without departing from the scope and spirit of this disclosure. This processing method may be carried out using a plasma processing apparatus that uses any plasma source, such as an inductively coupled plasma or microwave plasma, in addition to the capacitively coupled plasma processing apparatus 1. [Explanation of Symbols]

[0122] 1...Plasma processing apparatus, 2...Control unit, 10...Plasma processing chamber, 10s...Plasma processing space, 11...Substrate support unit, 13...Shower head, 20...Gas supply unit, 31a...First RF generation unit, 31b...Second RF generation unit, 32a...First DC generation unit, SF...Silicon-containing film, MF...Mask, OP...Opening, RC...Recess, UF...Undercoat, W...Substrate

Claims

1. (a) A step of providing a substrate having a silicon-containing film containing silicon and nitrogen, and a mask on the silicon-containing film, onto a substrate support portion in a chamber, (b) A step of supplying a processing gas containing hydrogen fluoride gas and a chlorine-containing gas into the chamber, wherein the chlorine-containing gas is BCl ３ The process involves a gas, wherein the flow rate of the chlorine-containing gas is 1.5% by volume or more of the total flow rate of the treatment gas excluding the inert gas, (c) An etching method comprising the step of generating plasma from the processing gas and etching the silicon-containing film.

2. The etching method according to claim 1, wherein the processing gas further comprises phosphorus fluoride gas.

3. The aforementioned phosphorus fluoride gas is PF ３ Gas and PF ５ The etching method according to claim 2, wherein the etching method is at least one of the gases.

4. The etching method according to claim 1, wherein the flow rate of the chlorine-containing gas is 5 volume percent or less of the total flow rate of the processing gas excluding the inert gas.

5. (a) A step of providing a substrate having a silicon-containing film containing silicon and nitrogen, and a mask on the silicon-containing film, onto a substrate support portion in a chamber, (b) A step of supplying a processing gas containing hydrogen fluoride gas and chlorine-containing gas into the chamber, wherein the chlorine-containing gas contains CHCl3 gas or CH2Cl2 gas, and the flow rate of the chlorine-containing gas is 1.5 volume percent or more of the total flow rate of the processing gas excluding the inert gas, (c) An etching method comprising the step of generating plasma from the processing gas and etching the silicon-containing film.

6. The etching method according to claim 5, wherein the processing gas further comprises a phosphorus-containing gas.

7. The etching method according to claim 1, wherein the processing gas, excluding the inert gas, has the highest flow rate of the hydrogen fluoride gas.

8. The etching method according to any one of claims 1 to 7, wherein the processing gas further comprises a carbon-containing gas.

9. The etching method according to claim 8, wherein the carbon-containing gas is either a fluorocarbon gas or a hydrofluorocarbon gas.

10. The etching method according to claim 8, wherein the processing gas further comprises at least one of an oxygen-containing gas and a metal-containing gas.

11. The etching method according to any one of claims 1 to 7, wherein the silicon-containing film further comprises a silicon nitride film and at least one of a silicon oxide film and a polysilicon film.

12. The etching method according to any one of claims 1 to 7, wherein the mask is a carbon-containing film or a metal-containing film.

13. The etching method according to any one of claims 1 to 7, wherein in step (c), the temperature of the substrate support portion is set to 0°C or lower.

14. (a) A step of providing a substrate having a silicon-containing film containing silicon and nitrogen, and a mask on the silicon-containing film, onto a substrate support portion in a chamber, (b) A step of supplying a processing gas into the chamber, the processing gas comprising a single gas or mixed gas containing fluorine and hydrogen and a chlorine-containing gas, wherein the chlorine-containing gas is BCl ３ The process involves a gas, wherein the flow rate of the chlorine-containing gas is 1.5% by volume or more of the total flow rate of the treatment gas excluding the inert gas, (c) An etching method comprising the steps of generating plasma from the processing gas and etching the silicon-containing film, wherein the plasma contains an active species of hydrogen fluoride.

15. The etching method according to claim 14, wherein the single gas or mixed gas containing fluorine and hydrogen is at least one selected from the group consisting of hydrogen fluoride gas, hydrofluorocarbon gas, and a mixed gas containing a fluorine-containing gas and a hydrogen-containing gas.

16. A plasma processing system comprising a chamber, a substrate support section provided within the chamber, a plasma generation section, and a control section, The control unit, (a) Control for providing a substrate having a silicon-containing film containing silicon and nitrogen, and a mask on the silicon-containing film, onto a substrate support portion in a chamber, (b) Control for supplying a processing gas containing hydrogen fluoride gas and a chlorine-containing gas into the chamber, wherein the chlorine-containing gas is BCl ３ The gas is controlled such that the flow rate of the chlorine-containing gas is 1.5% by volume or more of the total flow rate of the treatment gas excluding the inert gas. (c) A plasma processing system that performs control to generate plasma from the processing gas and etch the silicon-containing film.

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