Plasma processing apparatus, etching method, semiconductor device manufacturing method, program, and storage medium

Abstract

To provide a technique of suppressing abnormal shaping of etching.SOLUTION: A plasma processor includes a chamber, a substrate supporting unit in the chamber, a plasma generation unit, and a control unit. The control unit performs the steps of: arranging a substrate having a silicon-containing film and a mask film on the silicon-containing film, on the substrate supporting unit (step a); supplying processing gas including tungsten-containing gas and hydrogen fluoride gas into the chamber (step b), the flow rate of the tungsten-containing gas being not larger than a 1 volume% of the total flow rate of the processing gas; and generating a plasma from the processing gas and etching the silicon-containing film (step c).SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent Document 1 discloses a method for etching a multilayer film in which silicon oxide films and silicon nitride films are alternately stacked. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-39310 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for suppressing etching shape abnormalities. [Means for solving the problem]

[0005] In one exemplary embodiment of the present disclosure, there is provided a plasma processing apparatus including a chamber, a substrate support within the chamber, a plasma generation unit, and a controller, wherein the controller is configured to perform a process including: (a) placing a substrate, having a silicon-containing film and a mask film on the silicon-containing film, on the substrate support; (b) supplying a process gas, including a tungsten-containing gas and a hydrogen fluoride gas, into the chamber, wherein a flow rate of the tungsten-containing gas is 1 volume % or less with respect to a total flow rate of the process gas; and (c) generating plasma from the process 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 etching shape abnormalities can be provided. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 illustrates a schematic diagram of an exemplary plasma processing system. [Figure 2] 1 is a flowchart illustrating an example of the present processing method. [Figure 3] 2 is a diagram showing an example of a cross-sectional structure of a substrate W. FIG. [Figure 4] 10 is a diagram showing an example of a cross-sectional structure of a substrate W being processed in step ST32. FIG. [Figure 5] FIG. 10 is a diagram showing an example of a cross-sectional structure of the substrate W after processing in step ST32. [Figure 6] FIG. 10 is a diagram showing the results of etching according to an example and a reference example. [Figure 7] FIG. 10 is a diagram showing the results of etching according to an example. DETAILED DESCRIPTION OF THE INVENTION

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

[0009] In one exemplary embodiment, there is provided a plasma processing apparatus including a chamber, a substrate support within the chamber, a plasma generating unit, and a controller, wherein the controller is configured to perform a process including: (a) placing a substrate, the substrate support having a silicon-containing film and a mask film on the silicon-containing film; (b) supplying a process gas, the process gas including a tungsten-containing gas and a hydrogen fluoride gas, into the chamber, wherein a flow rate of the tungsten-containing gas is 1% by volume or less with respect to a total flow rate of the process gas; and (c) generating a plasma from the process gas to etch the silicon-containing film.

[0010] In one exemplary embodiment, the tungsten-containing gas has the lowest flow rate of any gas contained in the process gas.

[0011] In one exemplary embodiment, the tungsten-containing gas is WF a Clb (where a and b are integers between 0 and 6, and the sum of a and b is between 2 and 6)

[0012] In one exemplary embodiment, the tungsten-containing gas is at least one of WF6 gas and WCl6 gas.

[0013] In one exemplary embodiment, the process gas further comprises at least one gas selected from the group of a carbon-containing gas, an oxygen-containing gas, and a halogen-containing gas other than fluorine.

[0014] In one exemplary embodiment, the process gas further comprises a phosphorus-containing gas.

[0015] In one exemplary embodiment, the phosphorus-containing gas is PF3 gas, PF5 gas, POF3 gas, HPF6 gas, PCl3 gas, PCl5 gas, POCl3 gas, PBr3 gas, PBr5 gas, POBr3 gas, PI3 gas, PO 10 The gas contains at least one selected from the group consisting of gas, P4O8 gas, P4O6 gas, PH3 gas, Ca3P2 gas, H3PO4 gas, and Na3PO4 gas.

[0016] In one exemplary embodiment, the controller is configured in (c) to control the temperature of the substrate support to 0° C. or less.

[0017] In one exemplary embodiment, the plasma generator is configured to provide a source signal and further comprises a DC or RF generator configured to provide a bias signal to the substrate support, wherein the source signal and the bias signal are both continuous wave or one continuous wave and the other pulsed wave.

[0018] In one exemplary embodiment, the apparatus further comprises a DC generator configured to apply a first DC signal to the substrate support.

[0019] In one exemplary embodiment, the device further comprises a waveform generator coupled to the DC generator for generating the sequence of voltage pulses from the first DC signal.

[0020] In one exemplary embodiment, the controller is configured to perform, in (c), a process of forming a recess having an aspect ratio of 20 or greater in the silicon-containing film.

[0021] In one exemplary embodiment, the silicon-containing film includes at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a laminated film in which silicon oxide films and polycrystalline silicon films are alternately laminated, and a laminated film in which silicon oxide films and silicon nitride films are alternately laminated.

[0022] In one exemplary embodiment, the mask film is a single-layer mask or a multi-layer mask including at least one selected from the group consisting of a polysilicon film, a boron-doped silicon film, a tungsten-containing film, an amorphous carbon film, a tin oxide film, and a titanium-containing film.

[0023] In one exemplary embodiment, there is provided a plasma processing apparatus including an H chamber, a substrate support within the chamber, a plasma generation unit, and a controller, wherein the controller is configured to perform a process including: (a) placing a substrate, the substrate having a silicon-containing film and a mask film on the silicon-containing film, on the substrate support; (b) supplying a process gas into the chamber, the process gas including a tungsten-containing gas and a gas capable of generating HF species, wherein the total flow rate of the tungsten-containing gas is 1% by volume or less with respect to the total flow rate of the process gas; and (c) generating plasma from the process gas, and etching the silicon-containing film with the HF species contained in the plasma.

[0024] In one exemplary embodiment, an etching method is provided, including: (a) placing a substrate having a silicon-containing film and a mask film on the silicon-containing film on a substrate support in a chamber; (b) supplying a process gas into the chamber, the process gas including a tungsten-containing gas and a hydrogen fluoride gas, wherein a flow rate of the tungsten-containing gas is 1% by volume or less with respect to a total flow rate of the process gas; and (c) generating a plasma from the process gas to etch the silicon-containing film.

[0025] In one exemplary embodiment, a method for manufacturing a semiconductor device is provided, including: (a) placing a substrate having a silicon-containing film and a mask film on the silicon-containing film on a substrate support in a chamber; (b) supplying a process gas into the chamber, the process gas including a tungsten-containing gas and a hydrogen fluoride gas, wherein a flow rate of the tungsten-containing gas is 1% by volume or less with respect to a total flow rate of the process gas; and (c) generating a plasma from the process gas to etch the silicon-containing film.

[0026] In one exemplary embodiment, a program is provided that causes a computer of a plasma processing system including a chamber, a substrate support within the chamber, and a plasma generation unit to execute the following controls: (a) placing a substrate, the substrate support having a silicon-containing film and a mask film on the silicon-containing film; (b) supplying a process gas, the process gas including a tungsten-containing gas and a hydrogen fluoride gas, into the chamber, wherein the flow rate of the tungsten-containing gas is 1% by volume or less with respect to the total flow rate of the process gas; and (c) generating plasma from the process gas to etch the silicon-containing film.

[0027] In one exemplary embodiment, a storage medium having a program stored thereon is provided.

[0028] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are designated by the same reference numerals, and redundant explanations will be omitted. Unless otherwise specified, the positional relationships, such as up, down, left, and right, will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

[0029] <Configuration example of plasma processing system> An example of the configuration of a plasma processing system will be described below: Fig. 1 is a diagram illustrating an example of the configuration of a capacitively coupled plasma processing apparatus.

[0030] The plasma processing system includes a capacitively coupled plasma processing device 1 and a controller 2. The capacitively coupled plasma processing device 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing device 1 also includes a substrate support 11 and a gas inlet. The gas inlet is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one process gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support 11 are electrically isolated from the plasma processing chamber 10 housing.

[0031] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting a substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the edge 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 disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that the annular region 111b may also be provided by another member surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Alternatively, an RF or DC electrode may be disposed within the ceramic member 1111a, in which case the RF or DC electrode functions as the lower electrode. When a bias RF signal or DC signal, which will be described later, is connected to the RF or DC electrode, the RF or DC electrode is also called a bias electrode. Note that both the conductive member of the base 1110 and the RF or DC electrode may function as two lower electrodes.

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

[0034] The substrate support 11 may also include a temperature adjustment module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature adjustment module may include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow path 1110a. In one embodiment, the flow path 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. The substrate support 11 may also include a heat transfer gas supply configured to supply a heat transfer gas between the backside 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 multiple gas inlets 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 from the multiple gas inlets 13c. The showerhead 13 also includes an upper electrode. In addition to the showerhead 13, the gas inlet may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[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 process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.

[0037] 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), such as a source RF signal and a bias RF signal, to at least one lower electrode and / or at least one upper electrode. This causes a plasma to be formed from at least one process gas supplied to the plasma processing space 10s. Thus, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate a plasma from one or more process gases in the plasma processing chamber 10. Furthermore, supplying a bias RF signal to the at least one lower electrode generates a bias potential on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0038] In one embodiment, the RF power supply 31 includes a first RF generating unit 31a and a second RF generating unit 31b. The first RF generating unit 31a is coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one embodiment, the source RF signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first RF generating unit 31a may be configured to generate multiple source RF signals having different frequencies. The generated one or more source RF signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0039] The second RF generating unit 31b is coupled to at least one lower electrode via at least one impedance matching circuit and 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 generating unit 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0040] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first bias DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 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 the at least one upper electrode.

[0041] In various embodiments, at least one of the first and second DC signals may be pulsed. In this case, a sequence of DC-based 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. In one embodiment, a waveform generator for generating a sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have either positive or negative polarity. Furthermore, the sequence of voltage pulses may include one or more positive voltage pulses and one or more negative voltage pulses within one period. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, or the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0042] The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure 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] The controller 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The controller 2 may be configured to control each element of the plasma processing apparatus 1 to perform various processes described herein. In one embodiment, part or all of the controller 2 may be included in the plasma processing apparatus 1. The controller 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to read a program from the storage unit 2a2 and execute the read program to perform various control operations. The program may be stored in the storage unit 2a2 in advance or may be acquired via a medium when needed. The acquired program is stored in the storage unit 2a2 and read from the storage unit 2a2 by the processing unit 2a1 for execution. The medium may be various storage media readable by the computer 2a or a communication line connected to the communication interface 2a3. The storage unit 2a2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or a combination thereof. The communication interface 2a3 may communicate with the plasma processing apparatus 1 via a communication line such as a local area network (LAN).

[0044] <An example of a plasma processing method> 2 is a flowchart showing a plasma processing method (hereinafter also referred to as "this processing method") according to one example embodiment. As shown in FIG. 2, this processing method includes step ST1 of providing a substrate, step ST2 of setting the temperature of a substrate support, and step ST3 of etching a target film on the substrate. The processing in each step may be performed in the plasma processing system shown in FIG. 1. The following describes an example in which a controller 2 controls each part of the plasma processing apparatus 1 to perform this processing method on a substrate W.

[0045] (Process ST1: Providing the substrate) In step ST1, the substrate W is provided in the plasma processing space 10s of the plasma processing apparatus 1. The substrate W is placed on the upper surface of the substrate support 11 so as to face the upper electrode, and is held on the substrate support 11 by the electrostatic chuck 1111.

[0046] 3 is a diagram showing an example of the cross-sectional structure of the substrate W provided in step ST1. The substrate W has an etching target film EF and a mask film MF formed in this order on an undercoat film UF. The substrate W may be used in the manufacture of semiconductor devices including semiconductor memory devices such as DRAMs and 3D-NAND flash memories.

[0047] The base film UF may be, for example, a silicon wafer, an organic film formed on a silicon wafer, a dielectric film, a metal film, a semiconductor film, etc. The base film UF may be configured by laminating a plurality of films.

[0048] The etching target film EF may be a silicon-containing film. For example, the silicon-containing film SF may be a silicon oxide film, a silicon nitride film, or a silicon oxynitride film. The etching target film EF may be formed by stacking multiple films. For example, the etching target film EF may be formed by alternately stacking silicon oxide films and polycrystalline silicon films. Alternatively, for example, the etching target film EF may be formed by alternately stacking silicon oxide films and silicon nitride films.

[0049] The base film UF and / or the etching target film EF may be formed by a CVD method, a spin coating method, etc. The base film UF and / or the etching target film EF may be a flat film, or may be a film having irregularities.

[0050] The mask film MF is formed on the etching target film EF. The mask film MF defines at least one opening OP on the etching target film EF. The opening OP is a space above the etching target film EF and is surrounded by the sidewall of the mask film MF. That is, in FIG. 3, the upper surface of the etching target film EF has an area covered by the mask film MF and an area exposed at the bottom of the opening OP.

[0051] The openings OP may have any shape when viewed from above the substrate W, i.e., when the substrate W is viewed from top to bottom in FIG. 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 film MF may have multiple side walls that define multiple openings OP. The multiple openings OP may each have a linear shape and be arranged at regular intervals to form a line-and-space pattern. Alternatively, the multiple openings OP may each have a hole shape and form an array pattern.

[0052] The mask film MF may be, for example, a polysilicon film, a boron-doped silicon film, a tungsten-containing film (e.g., a WC film, a WSi film, etc.), an amorphous carbon film, a tin oxide film, or a titanium-containing film (e.g., a TiN film, etc.). The mask film MF may be a single-layer mask consisting of one layer, or a multi-layer mask consisting of two or more layers. The mask film MF may be formed by a CVD method, a spin coating method, etc. The mask film MF may be formed by lithography. The opening OP may be formed by etching the mask film MF.

[0053] At least a part of the process for forming each component of the substrate W may be performed in the plasma processing chamber 10. In one example, the step of etching the mask film MF to form the opening OP may be performed in the plasma processing chamber 10. That is, the opening OP and the etching of the etching target film EF, which will be described later, may be performed consecutively in the same chamber. Alternatively, after all or part of each component of the substrate W is formed in an apparatus or chamber external to the plasma processing apparatus 1, the substrate W may be loaded into the plasma processing space 10s of the plasma processing apparatus 1 and placed on the upper surface of the substrate support 11.

[0054] (Substrate ST2: Temperature setting of substrate support part) In step ST2, the temperature of the substrate support 11 is set to a target temperature. The target temperature may be, for example, 0° C. or less. The target temperature may be −10° C. or less, −20° C. or less, −30° C. or less, −40° C. or less, −50° C. or less, −60° C. or less, or −70° C. or less.

[0055] Setting the temperature of the substrate support 11 to a target temperature includes, but is not limited to, measuring the temperature of the substrate support 11 and adjusting the temperature of the substrate support 11 using a temperature control module so that the temperature of the substrate support 11 becomes the target temperature. In one example, setting the temperature of the substrate support 11 to a target temperature includes (a) setting the temperature of the substrate W or the temperature of the heat transfer fluid flowing through the flow path 1110a to the target temperature or a temperature different from the target temperature so that the temperature of the substrate support 11 becomes the target temperature, and (b) setting the temperature of the substrate support 11 or the heat transfer fluid flowing through the flow path 1110a to the target temperature or a temperature different from the target temperature so that the temperature of the substrate W becomes the target temperature. Furthermore, "setting" a temperature includes inputting, selecting, or storing the temperature in the control unit 2.

[0056] In this processing method, step ST2 may be performed before step ST1. That is, the substrate W may be provided to the substrate support 11 after the temperature of the substrate support 11 is set to the target temperature.

[0057] (Step ST3: Etching of etching target film EF) In step ST3, the etching target film EF is etched. Step ST3 includes step ST31 of supplying a processing gas and step ST32 of generating plasma from the processing gas. During the processing in step ST3, the temperature of the substrate support 11 is set to the target temperature set in step ST2.

[0058] In step ST31, a processing gas is supplied into the plasma processing space 10s from the gas supply unit 20. The processing gas contains hydrogen fluoride (HF) gas and a tungsten-containing gas. The HF gas has a larger flow rate than the tungsten-containing gas.

[0059] The flow rate of HF gas may be the highest in the processing gas. In one example, the flow rate of HF gas may be 70 volume % or more, or even 80 volume % or more, of the total flow rate of the processing gas. The flow rate of HF gas may be 10 times or more, 50 times or more, 100 times or more, 300 times or more, or 500 times or more, of the tungsten-containing gas.

[0060] In place of or in addition to HF gas, a gas capable of generating HF species within the chamber may be used as the process gas. The HF species includes at least one of hydrogen fluoride gas, radicals, and ions. The HF species may be generated from at least one gas selected from the group consisting of HF gas and hydrofluorocarbon gases. The HF species may also be generated from a hydrofluorocarbon gas having two or more carbon atoms. Examples of gases capable of generating HF species include CH2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, and C5H2F 10 At least one selected from the group consisting of CH2F2 gas, C3H2F4 gas, C3H2F6 gas, and C4H2F6 gas may be used as the gas capable of generating HF species.

[0061] The tungsten-containing gas may be a gas containing tungsten and a halogen, and in one example is WF aCl b The tungsten-containing gas is a gas (where a and b are each an integer between 0 and 6, and the sum of a and b is between 2 and 6). Specifically, the tungsten-containing gas may be a gas containing tungsten and fluorine, such as tungsten difluoride (WF2) gas, tungsten tetrafluoride (WF4) gas, tungsten pentafluoride (WF5) gas, or 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. Among these, at least one of WF6 gas and WCl6 gas may be used. The flow rate of the tungsten-containing gas may be 5% by volume or less, or may be 1% by volume or less, 0.5% by volume or less, or 0.2% by volume or less, of the total flow rate of the processing gas.

[0062] The process gas may further contain at least one gas selected from the group consisting of a carbon-containing gas, an oxygen-containing gas, and a halogen-containing gas other than fluorine.

[0063] Carbon-containing gases are x F y Gas (x, y are positive integers). C x F y The gas may include at least one selected from the group consisting of C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 gas.

[0064] Carbon-containing gases are s H t F u It can also be a gas (s, t, u are positive integers). s H t F u Gases include 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, and C5H2F 10The processing gas may include at least one selected from the group consisting of C H F gas and C H F gas. x F y Gas and C s H t F u The gas may include both the gas and the gas.

[0065] 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 process gas may include an oxygen-containing gas other than H2O, i.e., at least one gas selected from the group consisting of O2, CO, CO2, and H2O2. The flow rate of the oxygen-containing gas is C x F y Gas and C s H t F u This may be adjusted according to the gas flow rate.

[0066] The halogen-containing gas other than fluorine may be a chlorine-containing gas, a bromine-containing gas, and / or an iodine-containing gas. Examples of the chlorine-containing gas include Cl2, SiCl2, SiCl4, CCl4, SiH2Cl2, Si2Cl6, CHCl3, SO2Cl2, BCl3, PCl3, PCl5, and POCl3. Examples of the bromine-containing gas include Br2, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3, and BBr3. Examples of the iodine-containing gas include HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3. In one example, the halogen-containing gas is at least one selected from the group consisting of Cl2 gas, Br2 gas, and HBr gas. In another example, Cl2 gas and HBr gas are used.

[0067] The process gas may further include a phosphorus-containing gas, such as PF3 gas, PF5 gas, POF3 gas, HPF6 gas, PCl3 gas, PCl5 gas, POCl3 gas, PBr3 gas, PBr5 gas, POBr3 gas, PI3 gas, or PO 10The gas may be at least one selected from the group consisting of PO gas, PO gas, PH gas, CaP gas, HPO gas, and NaPO gas. Among these gases, phosphorus halide-containing gases such as PF gas, PF gas, and PCl gas may be used, or phosphorus fluoride gases such as PF gas and PF gas may be used.

[0068] In step ST32, a source RF signal (RF power) is supplied from the first RF generator 31a to the lower electrode and / or the upper electrode. This generates plasma from the processing gas. In addition, a bias RF signal is supplied from the second RF generator 31b to the lower electrode as a bias signal (power), generating a bias potential on the substrate. This causes active species such as ions and radicals in the generated plasma to be attracted to the substrate W and pass through the opening OP in the mask film MF to etch the etching target film EF. As described above, the temperature of the substrate support member 11 is set to the target temperature during etching.

[0069] The timing at which the supply of the bias signal is started may be simultaneous with or different from the timing at which the supply of the source RF signal is started. A bias DC signal may be used as the bias signal (power). That is, a negative bias DC signal may be supplied from the DC generating unit 32a to the lower electrode to generate a bias potential on the substrate W. The source RF signal and the bias signal may both be continuous waves, or one may be a continuous wave and the other a pulse wave. The duty ratio of the pulse wave of the bias signal may be set appropriately. For example, the duty ratio may be 30% or less, or 20% or less. The duty ratio of the bias signal is the proportion of the period during which the power or voltage level is high in the pulse wave cycle.

[0070] 4 is a diagram showing an example of the cross-sectional structure of the substrate W during processing in step ST32. As shown in FIG. 4, a protective film PF containing tungsten is formed on the mask film MF. The protective film PF is formed, for example, by reducing tungsten in a tungsten-containing gas with activated hydrogen species in plasma, and adhering and depositing on the mask film MF. The protective film PF is formed on at least the sidewalls of the mask film MF. The protective film PF may also be formed on the upper surface of the mask film MF.

[0071] Tungsten in the protective film PF has low reactivity with HF species in the plasma. Therefore, the sidewalls of the mask film MF are prevented from being removed by etching during step ST32. This prevents the bowing CD of the mask film MF from expanding (i.e., bowing is suppressed). As an example, the bowing CD may be the maximum width of the opening OP in the mask film MF or the recess RC in the protective film PF.

[0072] 5 is a diagram showing an example of the cross-sectional structure of the substrate W after processing in step ST32. As shown in FIG. 5, step ST32 ends when the bottoms BT of the recesses RC formed in the etching target film EF by etching reach the base film UF, exposing the surface of the base film UF. Since bowing of the mask film MF is suppressed during execution of step ST32, bowing of the recesses RC formed in the etching target film EF is also suppressed. This processing method can thereby suppress defects in the shape of the recesses RC formed in the etching target film EF. The aspect ratio of the recesses RC may be 20 or more, or may be 30 or more, 40 or more, 50 or more, or 100 or more.

[0073] <Example> Next, examples of the present processing method will be described, but the present disclosure is not limited to the following examples.

[0074] Examples 1 and 2 In Examples 1 and 2, this processing method was applied using a plasma processing apparatus 1 to etch a substrate having a structure similar to that of the substrate W shown in FIG. 3. A polysilicon film was used as the mask film MF. A two-layer film consisting of a silicon nitride film formed on a silicon oxide film was used as the etching film EF. The processing gas contained HF gas, WF6 gas, C4F8 gas, and O2 gas. The processing gas in Example 1 contained 85% or more by volume of HF gas and 0.2% by volume of WF6 gas. The processing gas in Example 2 contained 85% or more by volume of HF gas and 0.5% by volume of WF6 gas. The target temperature of the substrate support during etching was set to -70°C. In addition, a pulse wave of a bias DC signal with a duty ratio of 20% was supplied to the lower electrode as a bias signal.

[0075] (Reference example 1) Using the plasma processing apparatus 1, a substrate similar to those in Examples 1 and 2 was etched. The processing gas in Reference Example 1 contained HF gas, C4F8 gas, and O2 gas, but did not contain WF6 gas. Except for this, etching was performed under the same etching conditions as in Examples 1 and 2.

[0076] FIG. 6 shows the results of etching according to Example 1, Example 2, and Reference Example 1. In FIG. 6, the vertical axis represents the depth D [μm] of the recess formed in the opening OP in the mask film MF and the etching target film EF. The area around 0 μm on the vertical axis is the boundary between the mask film MF and the silicon nitride film (SiN). The area around −0.2 μm on the vertical axis is the boundary between the silicon nitride film (SiN) and the silicon oxide film (SiOx). In FIG. 6, the horizontal axis represents the opening width CD [nm] of the opening OP in the mask film MF and the recess RC formed in the etching target film EF.

[0077] 6, in Examples 1 and 2 containing WF6 gas as the process gas, bowing of the mask film MF and silicon oxide film (SiOx) was suppressed compared to Reference Example 1, which did not contain WF6 gas. Specifically, the bowing CD of the mask film MF and silicon oxide film (SiOx) in Example 1 was 41 and 39, respectively. The bowing CD of the mask film MF and silicon oxide film (SiOx) in Example 2 was 43 and 39, respectively. In contrast, the bowing CD of the mask film MF and silicon oxide film (SiOx) in Reference Example 1 was 45 and 42, respectively. The bowing CD of the silicon oxide film (SiOx) was suppressed to the same extent as in Example 2 (WF6 gas: 0.5 vol%) even in Example 1, which contained a lower amount of WF6 gas (WF6 gas: 0.2 vol%).

[0078] Examples 3 and 4 This processing method was applied using a plasma processing apparatus 1 to etch the same substrate as in Examples 1 and 2. The processing gas in Examples 3 and 4 was the same as in Examples 1 and 2, except that it contained 0.3 volume % WF6 gas. In Example 3, the duty ratio of the pulse wave of the bias DC signal was set to 30%. In Example 4, the duty ratio of the pulse wave of the bias DC signal was set to 20%. Except for this point, etching was performed under the same etching conditions as in Examples 1 and 2.

[0079] FIG. 7 is a diagram showing the results of etching in Examples 3 and 4. The vertical and horizontal axes in FIG. 7 are the same as those in FIG. 6. As shown in FIG. 7, bowing of the mask film MF and the silicon oxide film (SiOx) was suppressed in both Examples 3 and 4. Example 4, in which the duty ratio of the bias DC signal was 20%, had a greater effect of suppressing bowing than Example 3, in which the duty ratio was 30%. This is thought to be because the low duty ratio relatively reduced the number of ions colliding with the substrate W, and the protective effect of the mask film MF by the protective film PF became more pronounced.

[0080] Embodiments of the present disclosure further include the following aspects.

[0081] (Appendix 1) A plasma processing method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a silicon-containing film and a mask film on the silicon-containing film on a substrate support in a chamber; (b) supplying a process gas containing a tungsten-containing gas and a hydrogen fluoride gas into the chamber, wherein the hydrogen fluoride gas is supplied into the chamber at a flow rate greater than a flow rate of the tungsten-containing gas; (c) generating a plasma from the process gas to etch the silicon-containing film; A plasma processing method comprising:

[0082] (Appendix 2) The tungsten-containing gas is WF a Cl b (a and b are each an integer of 0 or more and 6 or less, and the sum of a and b is 2 or more and 6 or less) gas.

[0083] (Appendix 3) 3. The plasma processing method according to claim 1, wherein the tungsten-containing gas is at least one of WF6 gas and WCl6 gas.

[0084] (Appendix 4) 4. The plasma processing method according to claim 1, wherein the hydrogen fluoride gas has the highest flow rate among the gases contained in the processing gas.

[0085] (Appendix 5) 5. The plasma processing method according to claim 1, wherein the flow rate of the tungsten-containing gas is the smallest among the gases contained in the processing gas.

[0086] (Appendix 6) 6. The plasma processing method according to claim 1, wherein a flow rate of the tungsten-containing gas is 5% by volume or less with respect to a total flow rate of the processing gas.

[0087] (Appendix 7) 7. The plasma processing method according to claim 1, wherein a flow rate of the hydrogen fluoride gas is 10 times or more a flow rate of the tungsten-containing gas.

[0088] (Appendix 8) 8. The plasma processing method according to claim 1, wherein the processing gas further contains at least one gas selected from the group consisting of a carbon-containing gas, an oxygen-containing gas, and a halogen-containing gas other than fluorine.

[0089] (Appendix 9) The carbon-containing gas is C x F y Gas (x, y are positive integers) or C s H t F u 9. The plasma processing method according to claim 8, wherein the gas is a gas (s, t, u are positive integers).

[0090] (Appendix 10) 10. The plasma processing method according to claim 1, wherein the processing gas further contains a phosphorus-containing gas.

[0091] (Appendix 11) 11. The plasma processing method according to claim 10, wherein the phosphorus-containing gas is a halogenated phosphorus gas.

[0092] (Appendix 12) 12. The plasma processing method according to any one of claims 1 to 11, wherein in (c), the temperature of the substrate support is set to 0° C. or lower.

[0093] (Appendix 13) Attachment 13. The plasma processing method according to claim 12, wherein in (c), the temperature of the substrate support is set to −50° C. or lower.

[0094] (Appendix 14) A plasma processing method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having a silicon-containing film and a mask film on the silicon-containing film on a substrate support in a chamber; (b) supplying a process gas into the chamber; (c) generating plasma from the processing gas and etching the silicon-containing film with HF species contained in the plasma; In the plasma processing method (b), the processing gas contains a tungsten-containing gas, and the tungsten-containing gas is supplied into the chamber at a flow rate of 5% by volume or less with respect to a total flow rate of the processing gas.

[0095] (Appendix 15) 15. The plasma processing method according to claim 14, wherein the HF species are generated from at least one gas selected from the group consisting of HF gas and hydrofluorocarbon gas.

[0096] (Appendix 16) 15. The plasma processing method according to claim 14, wherein the HF species are generated from a hydrofluorocarbon gas having two or more carbon atoms.

[0097] (Appendix 17) 15. The plasma processing method according to claim 14, wherein the HF species are generated from at least one gas selected from the group consisting of CH2F2 gas, C3H2F4 gas, C3H2F6 gas, and C4H2F6 gas.

[0098] (Appendix 18) A control unit is provided, The control unit (a) providing a substrate having a silicon-containing film and a mask film on the silicon-containing film on the substrate support; (b) supplying a process gas containing a tungsten-containing gas and a hydrogen fluoride gas into the chamber, the hydrogen fluoride gas being supplied into the chamber at a flow rate greater than a flow rate of the tungsten-containing gas; (c) generating a plasma from the process gas to etch the silicon-containing film; A plasma processing system performs the control.

[0099] Various modifications can be made to the embodiments of the present disclosure without departing from the scope and spirit of the present disclosure. For example, the present processing method may be performed using a plasma processing apparatus using any plasma source, such as an inductively coupled plasma or a microwave plasma, in addition to the capacitively coupled plasma processing apparatus 1. [Explanation of symbols]

[0100] REFERENCE SIGNS LIST 1: plasma processing apparatus, 2: control unit, 10: plasma processing chamber, 10s: plasma processing space, 11: substrate support unit, 13: shower head, 20: gas supply unit, 31a: first RF generation unit, 31b: second RF generation unit, 32a: first DC generation unit, EF: film to be etched, MF: mask film, OP: opening, PF: protective film, RC: recess, UF: base film, W: substrate

Claims

1. a chamber; a substrate support within the chamber; a plasma generating unit; A control unit; Equipped with The control unit (a) disposing a substrate having a silicon-containing film and a mask film on the silicon-containing film on the substrate support; (b) supplying a process gas containing a tungsten-containing gas and a hydrogen fluoride gas into the chamber, wherein a flow rate of the tungsten-containing gas is 1% by volume or less with respect to a total flow rate of the process gas; (c) generating a plasma from the process gas to etch the silicon-containing film; configured to perform a process including Plasma processing equipment.

2. 2. The plasma processing apparatus according to claim 1, wherein a flow rate of a tungsten-containing gas is the smallest among the gases contained in the processing gas.

3. The tungsten-containing gas is WF a Cl b 2. The plasma processing apparatus according to claim 1, wherein a and b are each an integer of 0 to 6, and the sum of a and b is 2 to 6.

4. The tungsten-containing gas is WF 6 Gas and WCl 6 2. The plasma processing apparatus according to claim 1, wherein the gas is at least one of the following gases:

5. 2. The plasma processing apparatus according to claim 1, wherein the processing gas further contains at least one gas selected from the group consisting of a carbon-containing gas, an oxygen-containing gas, and a halogen-containing gas other than fluorine.

6. The plasma processing apparatus of claim 1 , wherein the process gas further comprises a phosphorus-containing gas.

7. The phosphorus-containing gas is PF 3 Gas, PF 5 Gas, POF 3 Gas, HPF 6 Gas, PCl 3 Gas, PCl 5 Gas, POCl 3 Gas, PBr 3 Gas, PBr 5 Gas, POBr 3 Gas, PI 3 Gas, P 4 O 10 Gas, P 4 O 8 Gas, P 4 O 6 Gas, pH 3 Gas, Ca 3 P 2 Gas, H 3 P.O. 4 Gas and Na 3 P.O. 4 The plasma processing apparatus according to claim 6 , further comprising at least one gas selected from the group consisting of:

8. The plasma processing apparatus of claim 1 , wherein the control unit is configured to control the temperature of the substrate support unit to 0° C. or less in (c).

9. the plasma generating unit is configured to provide a source signal; a DC generator or an RF generator configured to provide a bias signal to the substrate support; 2. The plasma processing apparatus according to claim 1, wherein the source signal and the bias signal are both continuous waves, or one is a continuous wave and the other is a pulse wave.

10. The plasma processing apparatus of claim 1 , further comprising a DC generator configured to apply a first DC signal to the substrate support.

11. The plasma processing apparatus of claim 10 , further comprising a waveform generator coupled to the DC generator for generating a sequence of voltage pulses from the first DC signal.

12. The plasma processing apparatus of claim 1 , wherein the control unit is configured to perform a process of forming a recess having an aspect ratio of 20 or more in the silicon-containing film in the step (c).

13. 2. The plasma processing apparatus according to claim 1, wherein the silicon-containing film comprises at least one selected from the group consisting of a silicon oxide film, a silicon nitride film, a silicon oxynitride film, a laminated film in which a silicon oxide film and a polycrystalline silicon film are alternately laminated, and a laminated film in which a silicon oxide film and a silicon nitride film are alternately laminated.

14. 2. The plasma processing apparatus according to claim 1, wherein the mask film is a single-layer mask or a multi-layer mask including at least one selected from the group consisting of a polysilicon film, a boron-doped silicon film, a tungsten-containing film, an amorphous carbon film, a tin oxide film, and a titanium-containing film.

15. a chamber; a substrate support within the chamber; a plasma generating unit; A control unit; Equipped with The control unit (a) disposing a substrate having a silicon-containing film and a mask film on the silicon-containing film on the substrate support; (b) supplying into the chamber a process gas including a tungsten-containing gas and a gas capable of generating HF species, wherein a total flow rate of the tungsten-containing gas is 1% by volume or less of a total flow rate of the process gas; (c) generating a plasma from the processing gas and etching the silicon-containing film with HF species contained in the plasma; configured to perform a process including Plasma processing equipment.

16. (a) placing a substrate having a silicon-containing film and a mask film on the silicon-containing film on a substrate support in a chamber; (b) supplying a process gas containing a tungsten-containing gas and a hydrogen fluoride gas into the chamber, wherein a flow rate of the tungsten-containing gas is 1% by volume or less with respect to a total flow rate of the process gas; (c) generating a plasma from the process gas to etch the silicon-containing film; An etching method comprising:

17. (a) placing a substrate having a silicon-containing film and a mask film on the silicon-containing film on a substrate support in a chamber; (b) supplying a process gas containing a tungsten-containing gas and a hydrogen fluoride gas into the chamber, wherein a flow rate of the tungsten-containing gas is 1% by volume or less with respect to a total flow rate of the process gas; (c) generating a plasma from the process gas to etch the silicon-containing film; A method for manufacturing a semiconductor device, comprising:

18. a computer for a plasma processing system including a chamber, a substrate support within the chamber, and a plasma generating unit; (a) controlling a substrate having a silicon-containing film and a mask film on the silicon-containing film to be positioned on the substrate support; (b) controlling a supply of a process gas containing a tungsten-containing gas and a hydrogen fluoride gas into the chamber, wherein a flow rate of the tungsten-containing gas is 1% by volume or less with respect to a total flow rate of the process gas; (c) generating a plasma from the processing gas to etch the silicon-containing film; A program that executes.

19. A storage medium storing the program according to claim 18.

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