Plasma processing method and plasma processing system

Abstract

The present invention provides a plasma processing method and a plasma processing system for suppressing abnormal shapes of etching. The plasma processing method performed in a plasma processing device having a chamber includes: step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; and step (b), etching the silicon-containing film, wherein step (b) includes: step (b-1), etching the silicon-containing film using plasma generated from a first processing gas containing hydrogen fluoride gas and a tungsten-containing gas; and step (b-2), etching the silicon-containing film using plasma generated from a second processing gas containing hydrogen fluoride gas, the second processing gas not containing a tungsten-containing gas, or containing a tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first processing gas.

Description

Technical Field

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

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

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2016-39310 Summary of the invention

[0006] Problem that the invention aims to solve

[0007] The present disclosure provides a technology for suppressing shape abnormality in etching.

[0008] Solutions for solving problems

[0009] In an exemplary embodiment of the present disclosure, a plasma processing method performed in a plasma processing apparatus having a chamber is provided, the plasma processing method comprising: step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; and step (b), etching the silicon-containing film, wherein the step (b) comprises: step (b-1), etching the silicon-containing film using plasma generated from a first processing gas containing hydrogen fluoride gas and a tungsten-containing gas; and step (b-2), etching the silicon-containing film using plasma generated from a second processing gas containing hydrogen fluoride gas, the second processing gas not containing a tungsten-containing gas, or containing a tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first processing gas.

[0010] Effects of the Invention

[0011] According to an exemplary embodiment of the present disclosure, a technique for suppressing shape abnormality in etching can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 FIG. 1 is a diagram schematically showing an exemplary plasma processing system.

[0013] Figure 2 This is a flowchart showing an example of the present processing method.

[0014] Figure 3 FIG. 2 is a diagram showing an example of a cross-sectional structure of a substrate W. FIG.

[0015] Figure 4A It is a timing chart showing an example of the flow rate of the HF-containing gas supplied in step ST2.

[0016] Figure 4B It is a timing chart showing an example of the flow rate of the tungsten-containing gas supplied in step ST2.

[0017] Figure 4C It is a timing chart showing an example of the flow rate of the phosphorus-containing gas supplied in step ST2.

[0018] Figure 5A 1 is a diagram showing a cross-sectional structure of a substrate W being processed in step ST2 .

[0019] Figure 5B 1 is a diagram showing a cross-sectional structure of a substrate W being processed in step ST2 .

[0020] Figure 5C 1 is a diagram showing a cross-sectional structure of a substrate W being processed in step ST2 .

[0021] Figure 5D 1 is a diagram showing a cross-sectional structure of a substrate W being processed in step ST2 .

[0022] Figure 6 This is a flowchart showing a modified example of the present processing method.

[0023] Figure 7 This is a flowchart showing a modified example of the present processing method.

[0024] Figure 8 It is a figure which shows the etching result of Example 3 and Reference Example 4.

[0025] Fig. 9 The diagram shows the etching results of Example 3, Example 4, Reference Example 4, and Reference Example 5. DETAILED DESCRIPTION

[0026] Hereinafter, each embodiment of the present disclosure will be described.

[0027] In an exemplary embodiment, a plasma processing method performed in a plasma processing apparatus having a chamber is provided, the plasma processing method comprising: step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; and step (b), etching the silicon-containing film, wherein step (b) comprises: step (b-1), etching the silicon-containing film using plasma generated from a first processing gas containing hydrogen fluoride gas and a tungsten-containing gas; and step (b-2), etching the silicon-containing film using plasma generated from a second processing gas containing hydrogen fluoride gas, the second processing gas not containing the tungsten-containing gas, or containing the tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first processing gas.

[0028] In an exemplary embodiment, in step (b), step (b-1) and step (b-2) are performed alternately and repeatedly.

[0029] In an exemplary embodiment, in step (b), a cycle including step (b-1) and step (b-2) is repeated multiple times, and in step (b-1) of at least one cycle of the cycles starting from the second cycle, the flow ratio of the tungsten-containing gas to the first processing gas is smaller than the flow ratio in step (b-1) of the first cycle.

[0030] In an exemplary embodiment, at least one of the tungsten-containing gas included in the first process gas and the tungsten-containing gas included in the second process gas is WF a Cl b Gas, wherein a and b are each an integer greater than or equal to 0 and less than or equal to 6, and the sum of a and b is greater than or equal to 2 and less than or equal to 6.

[0031] In an exemplary embodiment, at least one of the tungsten-containing gas included in the first process gas and the tungsten-containing gas included in the second process gas is at least any one of WF6 gas and WCl6 gas.

[0032] In an exemplary embodiment, in the first process gas, the flow rate of the hydrogen fluoride gas is the largest among all gases except the inert gas.

[0033] In an exemplary embodiment, in the first process gas, the flow rate of the tungsten-containing gas is the smallest among all gases except the inert gas.

[0034] In an exemplary embodiment, in the first process gas, the flow rate of the hydrogen fluoride gas is more than 10 times the flow rate of the tungsten-containing gas.

[0035] In an exemplary embodiment, at least one of the first process gas and the second process gas further includes a phosphorus-containing gas.

[0036] In an exemplary embodiment, the phosphorus-containing gas is a phosphorus halide gas.

[0037] In an exemplary embodiment, at least one of the first process gas and the second process gas further includes a carbon-containing gas.

[0038] In an exemplary embodiment, the carbon-containing gas is any one of a fluorocarbon gas and a hydrofluorocarbon gas.

[0039] In an exemplary embodiment, at least one of the first process gas and the second process gas further includes an oxygen-containing gas.

[0040] In an exemplary embodiment, at least one of the first process gas and the second process gas further includes a gas containing a halogen other than fluorine.

[0041] In an exemplary embodiment, the mask has a hole pattern or a slit pattern.

[0042] In an exemplary embodiment, a plasma processing method performed in a plasma processing apparatus having a chamber is provided, the plasma processing method comprising: step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; and step (b), etching the silicon-containing film, wherein step (b) comprises: step (b-1), etching the silicon-containing film using a first plasma containing a hydrogen fluoride species and a chemical species, the chemical species containing at least any one of tungsten, titanium and molybdenum; and step (b-2), etching the silicon-containing film using a second plasma containing a hydrogen fluoride species, the second plasma not containing the chemical species or containing the chemical species at a partial pressure smaller than the partial pressure of the chemical species in the first plasma.

[0043] In an exemplary embodiment, the hydrogen fluoride species is generated from at least one of a hydrogen fluoride gas and a hydrofluorocarbon gas.

[0044] In an exemplary embodiment, the hydrogen fluoride species is generated from a hydrofluorocarbon gas having a carbon number of 2 or more.

[0045] In an exemplary embodiment, hydrogen fluoride species are generated from a fluorine-containing gas and a hydrogen-containing gas.

[0046] In an exemplary embodiment, a plasma processing system is provided, which includes a chamber, a substrate support portion arranged in the chamber, a plasma generating portion, and a control portion, wherein the control portion performs: control (a) to provide a substrate having a silicon-containing film and a mask on the silicon-containing film on the substrate support portion; and control (b) to etch the silicon-containing film, wherein control (b) includes: control (b-1) to etch the silicon-containing film using plasma generated from a first processing gas including hydrogen fluoride gas and a tungsten-containing gas; and control (b-2) to etch the silicon-containing film using plasma generated from a second processing gas including hydrogen fluoride gas, the second processing gas not containing the tungsten-containing gas, or containing the tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first processing gas.

[0047] Hereinafter, various embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. In addition, in each of the drawings, the same or identical elements are marked with the same reference numerals, and repeated descriptions are omitted. Unless otherwise stated, the positional relationships such as up, down, left, and right are 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.

[0048] <Configuration Example of Plasma Processing System>

[0049] Next, a configuration example of a plasma processing system will be described. Figure 1 It is a diagram for explaining a configuration example of a capacitive coupling type plasma processing apparatus.

[0050] The plasma processing system includes a capacitively coupled plasma processing device 1 and a control unit 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. In addition, the plasma processing device 1 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 disposed in the plasma processing chamber 10. The shower head 13 is disposed 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 wall 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 exhaust port for exhausting gas from the plasma processing space 10s. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10 .

[0051] The substrate support portion 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central area 111a for supporting a substrate W and an annular area 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. When viewed from above, the annular area 111b of the main body 111 surrounds the central area 111a of the main body 111. The substrate W is arranged on the central area 111a of the main body 111, and the ring assembly 112 is arranged on the annular area 111b of the main body 111 in a manner that surrounds the substrate W on the central area 111a of the main body 111. Therefore, the central area 111a is also referred to as a substrate supporting surface for supporting the substrate W, and the annular area 111b is also referred to as a ring supporting surface for supporting the edge ring assembly 112.

[0052] In one embodiment, the main body 111 includes a base 1110 and an electrostatic holding disk (chuck) 1111. The base 1110 includes a conductive component. The conductive component of the base 1110 can function as a lower electrode. The electrostatic holding disk 1111 is arranged on the base 1110. The electrostatic holding disk 1111 includes a ceramic component 1111a and an electrostatic electrode 1111b arranged in the ceramic component 1111a. The ceramic component 1111a has a central area 111a. In one embodiment, the ceramic component 1111a also has an annular area 111b. In addition, it is also possible that other components surrounding the electrostatic holding disk 1111, such as an annular electrostatic holding disk or an annular insulating component, have an annular area 111b. In this case, the ring assembly 112 can be arranged on the annular electrostatic holding disk or the annular insulating component, and can also be arranged on both the electrostatic holding disk 1111 and the annular insulating component. In addition, the RF or DC electrode can be arranged in the ceramic member 1111a, in which case the RF or DC electrode functions as a lower electrode. When the bias RF signal or DC signal described later is connected to the RF or DC electrode, the RF or DC electrode is also called a bias electrode. In addition, the RF or DC electrode and the conductive member of the base 1110 can function as two lower electrodes.

[0053] The ring assembly 112 includes one or more ring-shaped members. In one embodiment, the one or more ring-shaped members include one or more edge rings and at least one cover ring. The edge ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0054] In addition, the substrate support 11 may also include a temperature adjustment module, which is configured to adjust at least one of the electrostatic holding disk 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 gas flows through the flow path 1110a. In one embodiment, a flow path 1110a is formed in the base 1110, and one or more heaters are arranged in the ceramic component 1111a of the electrostatic holding disk 1111. In addition, the substrate support 11 may also include a heat transfer gas supply unit, which is configured to supply a heat transfer gas between the back side of the substrate W and the central area 111a.

[0055] The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 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 from the plurality of gas inlet ports 13c. In addition, the shower head 13 includes an upper electrode. In addition, the gas inlet portion may include, in addition to the shower head 13, one or more side gas injection portions (SGI: Side Gas Injector) installed in one or more openings formed in the side wall 10a.

[0056] 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 each corresponding gas source 21 to the shower head 13 via each corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. In addition, the gas supply unit 20 may also include one or more flow modulation devices for modulating or pulsing the flow of at least one process gas.

[0057] 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 provide 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. Thus, plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. In addition, by providing a bias RF signal to at least one lower electrode, a bias potential can be generated on the substrate W to attract ion components in the formed plasma to the substrate W.

[0058] 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 configured to be coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit, and to generate a source RF signal (source RF power) for generating plasma. 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 also be configured to generate a plurality of source RF signals having different frequencies. The generated one or more source RF signals are provided to at least one lower electrode and / or at least one upper electrode.

[0059] The second RF generating unit 31b is configured to be coupled to at least one lower electrode via at least one impedance matching circuit and 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 that 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 also be configured to generate a plurality of bias RF signals having different frequencies. The generated one or more bias RF signals are provided to at least one lower electrode. In addition, in various embodiments, at least one of the source RF signal and the bias RF signal may also be pulsed.

[0060] In addition, 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 generating unit 32a and a second DC generating unit 32b. In one embodiment, the first DC generating unit 32a is configured to be connected to at least one lower electrode and 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 generating unit 32b is configured to be connected to at least one upper electrode and generate a second DC signal. The generated second DC signal is applied to at least one upper electrode.

[0061] In various embodiments, at least one of the first DC signal and the second DC signal may also 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 pulse may have a pulse waveform of a rectangle, a trapezoid, a triangle, or a combination of these shapes. In one embodiment, a waveform generating unit for generating a sequence of voltage pulses from a DC signal is connected between the first DC generating unit 32a and at least one lower electrode. Thus, the first DC generating unit 32a and the waveform generating unit constitute a voltage pulse generating unit. In the case where the second DC generating unit 32b and the waveform generating unit constitute a voltage pulse generating unit, the voltage pulse generating unit is connected to at least one upper electrode. The voltage pulse may have a positive polarity or a negative polarity. In addition, the sequence of voltage pulses may also include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses in one cycle. Furthermore, the first DC generator 32a and the second DC generator 32b may be provided in addition to the RF power source 31, or the first DC generator 32a may be provided instead of the second RF generator 31b.

[0062] The exhaust system 40 can be connected to a gas outlet 10e, for example, provided at the bottom of the plasma processing chamber 10. The exhaust system 40 can include a pressure regulating valve and a vacuum pump. The pressure in the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump can include a turbomolecular pump, a dry pump, or a combination thereof.

[0063] The control unit 2 processes computer-executable commands that cause the plasma processing device 1 to perform various processes described in the present disclosure. The control unit 2 can be configured to control the various elements of the plasma processing device 1 to perform the various processes described herein. In one embodiment, a part or all of the control unit 2 may also be included in the plasma processing device 1. The control unit 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 can be configured to read a program from the storage unit 2a2 and perform various control actions by executing the read program. The program may be stored in the storage unit 2a2 in advance, or it may be obtained via a medium when necessary. The obtained program is stored in the storage unit 2a2, and is read and executed from the storage unit 2a2 by the processing unit 2a1. The medium may be various storage media that can be read by the computer 2a, or it may be a communication line connected to the communication interface 2a3. The storage unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), an 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).

[0064] <An Example of Plasma Treatment Method>

[0065] Figure 2 FIG. 1 is a flow chart showing a plasma processing method (hereinafter also referred to as “the present processing method”) according to an exemplary embodiment. Figure 2 As shown in FIG. 1 , the processing method includes a step ST1 of providing a substrate and a step ST2 of performing etching. Figure 1 The processing in each step is performed in the plasma processing system shown. Hereinafter, a case where the control unit 2 controls each unit of the plasma processing apparatus 1 to perform the processing method on the substrate W will be described as an example.

[0066] (Step ST1: Providing a Substrate)

[0067] In step ST1 , a substrate W is provided in the plasma processing space 10 s of the plasma processing apparatus 1 . The substrate W is provided in the central region 111 a of the substrate support 11 . The substrate W is held on the substrate support 11 by the electrostatic holding disk 1111 .

[0068] Figure 31 is a diagram showing an example of a cross-sectional structure of a substrate W provided in step ST1. The substrate W has a silicon-containing film SF and a mask MF stacked in sequence on a base film UF. The substrate W can be used for manufacturing semiconductor devices. Semiconductor devices include semiconductor memory devices such as DRAM and 3D-NAND flash memory.

[0069] In one example, the base film UF is a silicon wafer, an organic film formed on the silicon wafer, a dielectric film, a metal film, a semiconductor film, etc. The base film UF may be formed by stacking a plurality of films.

[0070] In the present processing method, the silicon-containing film SF is a film to be etched. In one example, the silicon-containing film SF is a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a polysilicon film. The silicon-containing film SF may be composed of a plurality of films stacked together. The silicon-containing film SF may be composed of at least two films selected from the group consisting of a silicon oxide film, a silicon nitride film, and a polysilicon film stacked together. For example, the silicon-containing film SF may be composed of a silicon oxide film and a silicon nitride film stacked alternately. In addition, for example, the silicon-containing film SF may be composed of a silicon oxide film and a polysilicon film stacked alternately.

[0071] The mask MF is a film that functions as a mask in etching the silicon-containing film SF. The mask 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.), a carbon-containing film (e.g., an amorphous carbon film, a spin-on carbon film, a photoresist film), or a tin oxide film or a titanium-containing film (e.g., a TiN film, etc.).

[0072] like Figure 3 As shown, 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 and is surrounded by the sidewalls of the mask MF. That is, the upper surface of the silicon-containing film SF has an area covered by the mask MF and an area exposed at the bottom of the opening OP.

[0073] When the substrate W is viewed from above, Figure 3 When the substrate W is viewed from the top down, the opening OP may have any shape. The shape may be, for example, a circle, an ellipse, a rectangle, a line, or a shape formed by combining one or more of these shapes. The mask MF may have a plurality of side walls, and the plurality of openings OP are defined by the plurality of side walls. The plurality of openings OP may each have a line shape, and may be arranged at fixed intervals to form a line and space pattern. In addition, the plurality of openings OP may each have a hole shape and form an array pattern.

[0074] Each film (base film UF, silicon-containing film SF, mask MF) constituting the substrate W can be formed by CVD method, ALD method, spin coating method, etc. The opening OP can be formed by etching the mask MF. In addition, the mask MF can be formed by photolithography. In addition, the above-mentioned films can be flat films, and can also be films with concave and convex surfaces. In addition, the substrate W can also have other films under the base film UF, and the stacked film of the silicon-containing film SF and the base film UF functions as a multi-layer mask. That is, the stacked film of the silicon-containing film SF and the base film UF can also be used as a multi-layer mask to etch the other film.

[0075] At least a part of the process of forming each film of the substrate W may also be performed in the space of the plasma processing chamber 10. In one example, the process of etching the mask MF to form the opening OP may be performed in the plasma processing chamber 10. That is, the etching of the opening OP and the silicon-containing film SF described later may be continuously performed in the same chamber. In addition, after all or a part of the films of the substrate W are formed in a device or chamber outside the plasma processing device 1, the substrate W may be moved into the plasma processing space 10s of the plasma processing device 1 and arranged in the central area 111a of the substrate support part 11, thereby providing the substrate.

[0076] After the substrate W is provided to the central area 111a of the substrate support part 11, the temperature of the substrate support part 11 is adjusted to a set temperature by the temperature adjustment module. The set temperature may be, for example, below 70°C, below 0°C, below -10°C, below -20°C, below -30°C, below -40°C, below -50°C, below -60°C, or below -70°C. In one example, adjusting or maintaining the temperature of the substrate support part 11 includes adjusting or maintaining the temperature of the heat transfer fluid flowing in the flow path 1110a to a set temperature or a temperature different from the set temperature. In one example, adjusting or maintaining the temperature of the substrate support part 11 includes controlling the pressure of the heat transfer gas (for example, He) between the electrostatic holding disk 1111 and the back surface of the substrate W. In addition, the timing of starting to circulate the heat transfer fluid to the flow path 1110a may be before or after the substrate W is placed on the substrate support part 11, or may be simultaneously. In addition, in the present processing method, the temperature of the substrate support part 11 may be adjusted to a set temperature before step ST1. That is, the substrate W may be provided to the substrate support portion 11 after the temperature of the substrate support portion 11 is adjusted to a set temperature.

[0077] (Step ST2: Etching)

[0078] In step ST2, the silicon-containing film SF of the substrate W is etched. Step ST2 includes a first etching step ST21 and a second etching step ST22. In addition, step ST2 may include a step ST23 for determining whether a stop condition of etching is satisfied. That is, step ST21 and step ST22 may be performed alternately and repeatedly until it is determined in step ST23 that the stop condition is satisfied. During the process in step ST2, the temperature of the substrate support 11 is maintained at the set temperature adjusted in step ST1.

[0079] (Step ST21: First Etching Step)

[0080] In step ST21, the silicon-containing film SF is etched using plasma generated from the first process gas. First, the first process gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The first process gas contains hydrogen fluoride (HF) gas and tungsten-containing gas. Next, a source RF signal is provided to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13. Thus, a high-frequency electric field is generated between the shower head 13 and the substrate support 11 to generate plasma from the first process gas in the plasma processing space 10s. In addition, a bias signal is provided to the lower electrode of the substrate support 11 to generate a bias potential between the plasma and the substrate W. Active species such as ions and free radicals in the plasma are attracted to the substrate W by the bias potential, and the silicon-containing film SF is etched by the active species.

[0081] (Step ST22: Second Etching Step)

[0082] In the second etching process ST22, the silicon-containing film SF is etched using the plasma generated from the second process gas. First, the second process gas is supplied from the gas supply unit 20 into the plasma processing space 10s. The second process gas may not contain a tungsten-containing gas. In addition, the second process gas may contain a tungsten-containing gas. In this case, the flow ratio of the tungsten-containing gas in the second process gas (the flow ratio of the tungsten-containing gas in the flow ratio of all gases except the inert gas) is smaller than the flow ratio of the tungsten-containing gas in the first process gas. That is, the second process gas may contain a tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first process gas. Next, a source RF signal is provided to the lower electrode of the substrate support 11 and / or the upper electrode of the shower head 13. Thus, a high-frequency electric field is generated between the shower head 13 and the substrate support 11 to generate plasma from the second process gas in the plasma processing space 10s. In addition, a bias signal is provided to the lower electrode of the substrate support 11 to generate a bias potential between the plasma and the substrate W. Active species such as ions and radicals in the plasma are attracted to the substrate W by the bias potential, and the silicon-containing film SF is etched by the active species, thereby forming a recessed portion based on the shape of the opening OP of the mask MF.

[0083] In step ST21 and step ST22, the bias signal may be a bias RF signal provided from the second RF generating unit 31b. In addition, the bias signal may be a bias DC signal provided from the first DC generating unit 32a. The source RF signal and the bias signal may be both continuous waves or pulse waves, or one may be a continuous wave and the other may be a pulse wave. In the case where both the source RF signal and the bias signal are pulse waves, the periods of the pulse waves of both may be synchronized. In addition, the duty cycle of the pulse wave may be appropriately set, for example, it may be 1 to 80%, or it may be 5 to 50%. In addition, the duty cycle is the proportion of the period of high power or voltage level in the period of the pulse wave. In addition, when a bias DC signal is used, the pulse wave may have a waveform of a rectangle, a trapezoid, a triangle, or a combination of these shapes. Regarding the polarity of the bias DC signal, it may be negative or positive as long as the potential of the substrate W can be set to provide a potential difference between the plasma and the substrate to attract ions.

[0084] (Step ST23: End determination)

[0085] In step ST23, it is determined whether the stop condition is satisfied. Regarding the stop condition, for example, steps ST21 and ST22 may be set as one cycle, and the stop condition is whether the number of repetitions of the cycle reaches a prescribed number of times. The stop condition may also be, for example, whether the etching time reaches a prescribed time. The stop condition may also be, for example, whether the depth of the recess formed by etching reaches a prescribed depth. When it is determined in step ST23 that the stop condition is not satisfied, the cycle including steps ST21 and ST22 is repeated. When it is determined in step ST23 that the stop condition is satisfied, the present processing method is terminated.

[0086] (Structure of Processing Gas)

[0087] As described above, the first process gas contains hydrogen fluoride (HF) gas and tungsten-containing gas. In addition, the second process gas contains hydrogen fluoride (HF) gas and does not contain tungsten-containing gas or contains tungsten-containing gas at a flow rate smaller than that of the tungsten-containing gas in the first process gas.

[0088] Alternatively, in the first process gas and / or the second process gas, the flow rate of HF gas is the largest among all gases except the inert gas. In one example, the HF gas may be 50% by volume or more, 60% by volume or more, 70% by volume or more relative to the total flow rate of HF gas except the inert gas, or may be 80% by volume or more. In addition, in the first process gas and / or the second process gas, the flow rate of hydrogen fluoride gas may be 10 times or more of the flow rate of tungsten-containing gas. In addition, as the HF gas, a high-purity HF gas, for example, a HF gas having a purity of 99.999% or more may be used.

[0089] When the second process gas includes a tungsten-containing gas, the tungsten-containing gas may be the same gas as the tungsten-containing gas included in the first process gas, or may be a different gas. Here, the tungsten-containing gas may be a gas containing tungsten and halogen, and in one example, WF a Cl b Gas (a and b are integers greater than 0 and less than 6, respectively, and the sum of a and b is greater than 2 and less than 6). Specifically, as a tungsten-containing gas, it can be 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, tungsten hexachloride (WCl6) gas. Among these gases, it can be at least any one of WF6 gas and WCl6 gas.

[0090] Alternatively, in the first processing gas and / or the second processing gas, the flow rate of the tungsten-containing gas is the smallest among all gases except the inert gas. In one example, the flow rate of the tungsten-containing gas may be less than 1 volume %, less than 0.5 volume %, less than 0.3 volume % or less than 0.2 volume % relative to the total flow rate of the processing gas except the inert gas. In one example, the flow rate of the tungsten-containing gas may be greater than 0.1 volume % relative to the total flow rate of the processing gas except the inert gas.

[0091] The first process gas may contain a titanium-containing gas or a molybdenum-containing gas instead of the tungsten-containing gas, or contain a titanium-containing gas or a molybdenum-containing gas in addition to the tungsten-containing gas. In this case, a chemical species of tungsten, titanium, or molybdenum is generated in the plasma generated from the first process gas. The second process gas may not contain a gas that generates the chemical species. In addition, the second process gas may contain a gas that generates the chemical species at a partial pressure smaller than the partial pressure of the gas in the first process gas.

[0092] The first process gas and / or the second process gas may further include a phosphorus-containing gas. When both the first process gas and the second process gas include a phosphorus-containing gas, the phosphorus-containing gases included in each gas may be the same gas or different gases.

[0093] The phosphorus-containing gas is a gas containing phosphorus-containing molecules. The phosphorus-containing molecules may be tetraphosphorus decoxide (P4O 10), tetraphosphorus octoxide (P4O8), tetraphosphorus hexaoxide (P4O6) and other oxides. Tetraphosphorus decoxide is sometimes called diphosphorus pentoxide (P2O5). Phosphorus-containing molecules can be halides (phosphorus halides) such as phosphorus trifluoride (PF3), phosphorus pentafluoride (PF5), phosphorus trichloride (PCl3), phosphorus pentachloride (PCl5), phosphorus tribromide (PBr3), phosphorus pentabromide (PBr5), and phosphorus triiodide (PI3). That is, the phosphorus-containing molecule can contain fluorine as a halogen element, such as phosphorus fluoride. Alternatively, the phosphorus-containing molecule can include halogen elements other than fluorine as a halogen element. The phosphorus-containing molecule can be a phosphorus halide such as phosphoryl fluoride (POF3), phosphoryl chloride (POCl3), and phosphoryl bromide (POBr3). The phosphorus-containing molecule can be phosphine (PH3), calcium phosphide (Ca3P2, etc.), phosphoric acid (H3PO4), sodium phosphate (Na3PO4), hexafluorophosphoric acid (HPF6), etc. The phosphorus-containing molecule may be a fluorophosphine (HgPFh). Here, the sum of g and h is 3 or 5. As fluorophosphine, HPF2 and H2PF3 are exemplified. The processing gas may contain one or more of the above-mentioned phosphorus-containing molecules as at least one phosphorus-containing molecule. For example, the processing gas may contain at least one of PF3, PCl3, PF5, PCl5, POCl3, PH3, PBr3 and PBr5 as at least one phosphorus-containing molecule. In addition, when each phosphorus-containing molecule contained in the first processing gas and / or the second processing gas is a liquid or solid, each phosphorus-containing molecule may be vaporized by heating or the like and supplied to the plasma processing space 10s.

[0094] Phosphorus-containing gas is PCl a F b Gas or PC c H d F e Gas, wherein a is an integer greater than or equal to 1, b is an integer greater than or equal to 0, a+b is an integer less than or equal to 5, d and e are each an integer greater than or equal to 1 and less than or equal to 5, and c is an integer greater than or equal to 0 and less than or equal to 9.

[0095] PCl a F b The gas may be, for example, at least one gas selected from the group consisting of PClF2 gas, PCl2F gas, and PCl2F3 gas.

[0096] PC c H d F e The gas may be, for example, at least one gas selected from the group consisting of PF2CH3 gas, PF(CH3)2 gas, PH2CF3 gas, PH(CF3)2 gas, PCH3(CF3)2 gas, PH2F gas and PF3(CH3)2 gas.

[0097] The phosphorus-containing gas may be PCl v F w C x H y Gas, wherein v, w, x, and y are each an integer greater than 1. In addition, the phosphorus-containing gas may be a gas containing P (phosphorus), F (fluorine), and a halogen other than F (fluorine) (for example, Cl, Br, or I) in its molecular structure, a gas containing P (phosphorus), F (fluorine), C (carbon), and H (hydrogen) in its molecular structure, or a gas containing P (phosphorus), F (fluorine), and H (hydrogen) in its molecular structure.

[0098] As the phosphorus-containing gas, a phosphine-based gas can be used. Examples of the phosphine-based gas include phosphine (PH3), compounds obtained by substituting at least one hydrogen atom of phosphine with an appropriate substituent, and phosphinic acid derivatives.

[0099] The substituent group substituting the hydrogen atom of phosphine is not particularly limited, and examples thereof include halogen atoms such as fluorine atoms and chlorine atoms, alkyl groups such as methyl groups, ethyl groups, and propyl groups, and hydroxyalkyl groups such as hydroxymethyl groups, hydroxyethyl groups, and hydroxypropyl groups. In one example, chlorine atoms, methyl groups, and hydroxymethyl groups are included.

[0100] Examples of the phosphinic acid derivatives include phosphinic acid (H 3 O 2 P), alkylphosphinic acid (PHO(OH)R) and dialkylphosphinic acid (PO(OH)R 2 ).

[0101] As the phosphine-based gas, for example, at least one gas selected from the group consisting of PCH3Cl2 (dichloro(methyl)phosphine) gas, P(CH3)2Cl (chloro(dimethyl)phosphine) gas, P(HOCH2)Cl2 (dichloro(hydroxymethyl)phosphine) gas, P(HOCH2)2Cl (chloro(dihydroxymethyl)phosphine) gas, P(HOCH2)(CH3)2(dimethyl(hydroxymethyl)phosphine) gas, P(HOCH2)2(CH3)(methyl(dihydroxymethyl)phosphine) gas, P(HOCH2)3(tris(hydroxymethyl)phosphine) gas, H3O2P (phosphinic acid) gas, PHO(OH)(CH3)(methylphosphonic acid) gas and PO(OH)(CH3)2(dimethylphosphonic acid) gas can be used.

[0102] The flow rate of the phosphorus-containing gas included in the first processing gas and / or the second processing gas may be less than 20 volume %, less than 10 volume %, or less than 5 volume % of the total flow rate of the processing gas including the phosphorus-containing gas excluding inert gases.

[0103] The first processing gas and / or the second processing gas may further include a carbon-containing gas. In the case where both the first processing gas and the second processing gas include a carbon-containing gas, the carbon-containing gases included in each of them may be the same gas or different gases. Here, the carbon-containing gas may be, for example, one or both of a fluorocarbon gas and a hydrofluorocarbon gas. In one example, the fluorocarbon gas may be selected from C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C 4F In one example, the hydrofluorocarbon gas may be at least one gas selected from the group consisting of 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, C5 ... 10 At least one gas selected from the group consisting of gas and C5H3F7 gas. In addition, the carbon-containing gas can be a straight-chain gas with unsaturated bonds. Regarding the straight-chain carbon-containing gas with unsaturated bonds, for example, it can be at least one gas selected from the group consisting of C3F6 (hexafluoropropylene) gas, C4F8 (octafluoro-1-butene, octafluoro-2-butene) gas, C3H2F4 (1,3,3,3,-tetrafluoropropylene) gas, C4H2F6 (trans-1,1,4,4,4-hexafluoro-2-butene) gas, C4F8O (perfluoroethyl trifluorovinyl ether) gas, CF3COF gas (1,2,2,2-tetrafluoroethane-1-one), CHF2COF (difluoroacetic acid fluoride) gas and COF2 (carbonyl fluoride) gas.

[0104] The first process gas and / or the second process gas may further include an oxygen-containing gas. In the case where both the first process gas and the second process gas include an oxygen-containing gas, the oxygen-containing gases included in each may be the same gas or different gases. Here, 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.

[0105] The first processing gas and / or the second processing gas may also contain a halogen gas other than fluorine. In the case where both the first processing gas and the second processing gas contain a halogen gas other than fluorine, the halogen gas other than fluorine included in each may be the same gas or a different gas. Here, the halogen gas other than fluorine may be a chlorine-containing gas, a bromine-containing gas and / or an iodine-containing gas. In one example, the chlorine-containing gas may be at least one gas selected from the group consisting of Cl2, SiCl2, SiCl4, CCl4, SiH2Cl2, Si2Cl6, CHCl3, SO2Cl2, BCl3, PCl3, PCl5 and POCl3. In one example, the bromine-containing gas may be at least one gas selected from the group consisting of Br2, HBr, CBr2F2, C2F5Br, PBr3, PBr5, POBr3 and BBr3. In one example, the iodine-containing gas may be at least one gas selected from the group consisting of HI, CF3I, C2F5I, C3F7I, IF5, IF7, I2, and PI3. In one example, the halogen-containing gas other than fluorine may be at least one gas selected from the group consisting of Cl2 gas, Br2 gas, and HBr gas. In one example, the halogen-containing gas other than fluorine is Cl2 gas or HBr gas.

[0106] The first processing gas and / or the second processing gas may further include an inert gas. When both the first processing gas and the second processing gas include an inert gas, the inert gases included in each may be the same gas or different gases. In one example, the inert gas may be a rare gas such as Ar gas, He gas, Kr gas, or nitrogen gas.

[0107] The first process gas and / or the second process gas may include a gas capable of generating HF species in plasma instead of the HF gas, or include a gas capable of generating HF species in plasma in addition to the HF gas. Here, the HF species includes at least one of hydrogen fluoride gas, free radicals, and ions.

[0108] The gas capable of generating HF species is, for example, a hydrofluorocarbon gas. The carbon number of the hydrofluorocarbon gas may be 2 or more, 3 or more, or 4 or more. In one example, the hydrofluorocarbon gas is at least one gas selected from the group consisting of CH2F2 gas, C3H2F4 gas, C3H2F6 gas, C3H3F5 gas, C4H2F6 gas, C4H5F5 gas, C4H2F8 gas, C5H2F6 gas, C5H2F10 gas, and C5H3F7 gas. In one example, the hydrofluorocarbon gas is at least one gas selected from the group consisting of CH2F2 gas, C3H2F4 gas, C3H2F6 gas, and C4H2F6 gas.

[0109] Gases capable of generating HF species include, for example, fluorine-containing gas and hydrogen-containing gas. Fluorine-containing gas is, for example, fluorocarbon gas. In one example, fluorocarbon gas is at least one gas selected from the group consisting of C2F2 gas, C2F4 gas, C3F6 gas, C3F8 gas, C4F6 gas, C4F8 gas, and C5F8 gas. In addition, fluorine-containing gas may be, for example, NF3 gas or SF6 gas. In one example, hydrogen-containing gas is at least one gas selected from the group consisting of H2 gas, CH4 gas, and NH3 gas.

[0110] Figure 4A to Figure 4C 1 is a timing chart showing an example of the flow rates of the HF gas, the tungsten-containing gas, and the phosphorus-containing gas in the process gas (the first process gas or the second process gas) in step ST2. Figure 4A to Figure 4C In the figure, the vertical axis represents the flow rate of each gas, and the horizontal axis represents time. Figure 4A In , F1 is a flow rate greater than 0. Figure 4B In the example, F2 is a flow rate greater than 0, and F3 is a flow rate less than F2 or 0. In one example, the relationship F1>F2>F3 holds. Figure 4C In the example, F4 is a flow rate greater than 0 or 0. Figure 4A to Figure 4C In the process ST21, period T1 (time t0 to time t1) and period T3 (time t2 to time t3) correspond to process ST21. In addition, period T2 (time t1 to time t2) and period T4 (time t3 to time t4) correspond to process ST22. The ratio of the duration of process ST21 (period T1 / T3) to the duration of process ST22 (period T2 / T4) can be appropriately set. For example, the ratio can be set in consideration of the balance between the protection of the mask MF described later and the suppression of clogging of the opening OP. For example, the ratio can be set in the range of 1:11 to 11:1. In addition, the duration of process ST21 can be the same or different in each cycle. That is, period T1 and period T3 can be the same or different. For example, the duration of process ST21 can be set according to the number of cycles. In one example, the duration of process ST21 can be shortened when the number of cycles exceeds a specified number of times or every specified number of cycles. Thus, the duration of step ST21 can be shortened as the recess RC formed in the silicon-containing film SF becomes deeper. Similarly, the duration of step ST22 can be the same or different in each cycle. That is, period T2 and period T4 can be the same or different.

[0111] Figure 5A to Figure 5D 1 is a diagram showing an example of a cross-sectional structure of a substrate W being processed in step ST2 . Figure 5A Show Figure 4A to Figure 4C An example of the cross-sectional structure of the substrate W at the end of the period T1 shown in FIG. Figure 5B to Figure 5DAn example of the cross-sectional structure of the substrate W at the end of each of the periods T2 to T4 is shown.

[0112] like Figure 5A As shown, by the process in the period T1 (step ST21 of the first cycle), the portion of the silicon-containing film SF exposed in the opening OP is thinned in the depth direction (in the Figure 5A The mask MF is etched in the direction from top to bottom in the process gas to form the recess RC. In addition, a protective film PF containing tungsten is formed on the mask MF. It is considered that the protective film PF is formed by the tungsten species in the plasma generated from the first process gas adhering and depositing on the mask MF. The protective film PF is formed on the side wall of the mask MF. The protective film PF may also be formed over the upper surface of the mask MF and at least a portion of the recess RC. The protective film PF may include byproducts generated by etching.

[0113] The reactivity between the tungsten in the protective film PF and the HF species in the plasma is low, and the protective film PF provides protection for the mask MF. That is, the protective film PF suppresses the shape deterioration of the mask MF due to the removal of the side walls of the mask MF by the HF species. Since the shape deterioration of the mask MF is suppressed, the number of ions that hit the side walls of the mask MF and go to the side walls of the silicon-containing film SF is reduced. As a result, the side walls of the silicon-containing film SF are suppressed from being etched in the lateral direction (left and right direction of FIG. 5) (bending). In addition, bending is one of the shape abnormalities of etching.

[0114] like Figure 5B As shown in FIG. 1 , by the process in period T2 (step ST22 of the first cycle), the silicon-containing film SF is further etched in the depth direction, and the depth of the recess RC increases. In period T2 (step ST22), the flow rate of the tungsten-containing gas supplied to the plasma processing space 10s is smaller than that in period T1 (step ST21) or is zero (see FIG. 1 ). Figure 4B ). Therefore, during the period T2, the deposition of the tungsten-containing film on the mask MF is reduced or zero, and the protective film PF is gradually removed. Moreover, at the end of the period T2 (step ST22), part or all of the protective film PF is removed. Thus, the width of the opening OP is suppressed from being narrowed or blocked by the protective film PF. In addition, at the end of the period T2, a part of the side wall of the mask MF may be removed.

[0115] like Figure 5C As shown in FIG. 1 , the silicon-containing film SF is further etched in the depth direction by the process in period T3 (step ST21 of the second cycle), and the depth of the recess RC increases. In addition, similarly to period T1 (step ST21 of the first cycle), a protective film PF is formed again on the mask MF. As described above, the protective film PF protects the mask MF and can suppress the bending of the silicon-containing film SF.

[0116] like Figure 5D As shown, by the process in period T4 (step ST22 of the second cycle), the silicon-containing film SF is further etched in the depth direction, and the depth of the recess RC becomes larger. Moreover, similarly to period T2 (step ST22 of the first cycle), at the end of period T4 (step ST22), part or all of the protective film PF is removed. Alternatively, at the end of period T4, part of the side wall of the mask MF is removed. In addition, Figure 5D The example in which the bottom BT reaches the base film UF at the end of the period T4 is shown, but the present invention is not limited thereto, and the bottom BT may reach the base film UF after three or more cycles. The aspect ratio of the concave portion RC in the state in which the bottom BT reaches the base film UF may be, for example, greater than 20, or greater than 30, greater than 40, greater than 50, or greater than 100.

[0117] In the present processing method, a cycle including step ST21 and step ST22 is repeated until it is determined in step ST23 that the stop condition is satisfied. In step ST21 (period T1 and period T3), the shape of the mask MF is suppressed from deteriorating due to etching by forming a protective film PF, thereby suppressing the bending of the silicon-containing film SF. In addition, in step ST22 (period T2 and period T4), by removing a part or all of the protective film PF formed in step ST21, the clogging of the opening OP can be suppressed, thereby suppressing the decrease in the etching rate of the silicon-containing film SF. In this way, according to the present processing method, by alternately and repeatedly forming (step ST21) and removing (step ST22) the protective film PF, etching can be performed in a manner that balances the protection of the mask MF and the suppression of the clogging of the opening OP. That is, the silicon-containing film SF can be etched while suppressing both the deterioration of the shape caused by the bending and the decrease in the etching rate.

[0118] <Modification>

[0119] The embodiments of the present disclosure can be modified in various ways without departing from the scope and spirit of the present disclosure.

[0120] For example, in Figure 4AAn example in which the flow rate of HF gas is fixed throughout the entire process ST2 is shown, but it is not limited to this. In one example, the flow rate of HF gas and / or the flow rate ratio in the process gas (hereinafter also referred to as "flow rate / flow rate ratio") can also be different in process ST21 (period T1, period T3, etc.) and process ST22 (period T2, period T4, etc.). In addition, the flow rate / flow rate ratio of HF gas can be changed in each cycle, for example, the flow rate / flow rate ratio can be different in a certain cycle (period T1, period T2) and another cycle (period T3, period T4). In addition, for example, the flow rate / flow rate ratio of HF gas can be changed during each etching process of process ST21 and process ST22. In one example, the flow rate / flow rate ratio of HF gas can be gradually or stagedly increased or decreased during period T1 (the same is true in periods T2, T3, T4, etc.). In addition, when the first process gas or the second process gas contains other gases such as phosphorus-containing gas, the flow rate of the other gas may not be fixed throughout the entire process ST2, and can be appropriately changed in the same way as described above.

[0121] In addition, for example, Figure 4B In the example shown, the flow rate (F2) of the tungsten-containing gas in process ST21 (period T1, period T3, etc.) and the flow rate / flow ratio of the tungsten-containing gas in process ST22 (period T2, period T4, etc.) are fixed, but not limited to this. For example, the flow rate / flow ratio of the tungsten-containing gas can be different in a certain cycle (period T1) of process ST21 and a certain other cycle (period T3). In addition, the flow rate / flow ratio of the tungsten-containing gas can be different in a certain cycle (period T2) of process ST22 and a certain other cycle (period T4). In one embodiment, the flow rate / flow ratio of the tungsten-containing gas can be set according to the number of cycles. For example, it can also be that when the number of cycles exceeds a specified number of times, or every specified number of cycles, the flow rate / flow ratio of the tungsten-containing gas in process ST21 (period T3, etc.) is reduced. Thus, it can be set that as the recess RC formed by etching becomes deeper, the flow rate / flow ratio of the tungsten-containing gas becomes smaller. In one example, the flow rate / flow ratio of the tungsten-containing gas in the step ST21 (period T3, etc.) of at least one of the cycles from the second time onwards may be smaller than the flow rate / flow ratio of the tungsten-containing gas in the step ST21 (period T1) of the first cycle. The amount of reduction in the flow rate / flow ratio of the tungsten-containing gas may be appropriately set, and in one example is less than 1 / 3 of the first cycle. In addition, for example, the flow rate / flow ratio of the tungsten-containing gas may be changed during each etching process of the step ST21 and the step ST22. In one example, the flow rate / flow ratio of the tungsten-containing gas may be gradually or stagedly increased or decreased during the period T1 (the same is true for the periods T2, T3, T4, etc.).

[0122] In addition, for example Figure 6 As shown, the order of step ST21 and step ST22 may be reversed. That is, the silicon-containing film SF may be etched first using the second process gas (step ST22), and then the silicon-containing film SF may be etched using the first process gas (step ST21).

[0123] In addition, for example Figure 7 As shown, it is possible to determine whether the stop condition is satisfied even after step ST21 is completed. That is, it is also possible to determine whether the stop condition is satisfied even after step ST21 is completed (step ST24), and when the stop condition is satisfied, etching is terminated without entering step ST22.

[0124] In other embodiments of the present disclosure, from the beginning or midway of step ST2, only step ST21 may be performed instead of alternately performing step ST21 (first etching) and step ST22 (second etching). In this case, the flow rate ratio of the tungsten-containing gas in step ST21 may be 0.1 volume % or more and 0.3 volume % or less relative to the total flow rate of the processing gas excluding the inert gas.

[0125] In addition, for example, the processing method may be performed using a plasma processing apparatus using any plasma source such as inductively coupled plasma or microwave plasma, in addition to the capacitively coupled plasma processing apparatus 1 .

[0126] <Example>

[0127] Next, examples of the present treatment method will be described. The present disclosure is not limited in any way by the following examples.

[0128] (Example 1)

[0129] In Example 1, the present treatment method is applied using a plasma treatment apparatus 1 to treat a Figure 3 A substrate having the same structure as the substrate W shown in the figure is etched. As the mask MF, an amorphous carbon film is used. As the silicon-containing film SF, a stacked film in which silicon nitride films and silicon oxide films are alternately stacked is used. The first processing gas used in step ST21 contains HF gas, phosphorus-containing gas and WF6 gas. The second processing gas used in step ST22 contains HF gas and phosphorus-containing gas. Moreover, the cycle of step ST21 (30 seconds) and step ST22 (30 seconds) is repeated 15 times, and etching is performed for a total of 15 minutes. During etching, the temperature of the substrate support 11 is set to 10°C.

[0130] (Reference Example 1 and Reference Example 2)

[0131] In Reference Examples 1 and 2, the plasma processing apparatus 1 was used to etch the substrate having the same structure as that of Example 1. In Reference Example 1, etching was performed for 15 minutes using the same processing gas as the first processing gas used in Example 1. In Reference Example 2, etching was performed for 15 minutes using the same processing gas as the second processing gas used in Example 1. In both Reference Examples 1 and 2, the temperature of the substrate support 11 was set to 10° C. during etching.

[0132] The etching depth: D [nm], curvature (maximum opening width): B [nm], the ratio of curvature (B) to etching depth (D): B / D and etching rate: E [nm / minute] of the silicon-containing film SF after etching of Example 1, Reference Example 1 and Reference Example 2 are shown in Table 1.

[0133]

Table 1

[0134] Example 1 Reference Example 1 Reference Example 2 D[nm] 6736 6295 7805 B[nm] 179.8 215.8 685.7 B / D 0.027 0.034 0.088 E[nm / min] 449.1 419.7 520.3

[0135] In Example 1, the ratio (B / D) of the bend (B) to the etching depth (D) is lower than that in Reference Example 1, and the bend is further suppressed. In addition, in Example 1, the etching rate is improved compared to Reference Example 1. In Example 1, the etching rate is reduced compared to Reference Example 2, but the ratio (B / D) of the bend to the etching depth D is greatly reduced, and the bend is greatly suppressed. That is, the etching of the silicon-containing film SF in Example 1 suppresses the bend and suppresses the decrease in the etching rate compared to Reference Examples 1 and 2.

[0136] (Example 2)

[0137] In Example 2, the present processing method was applied using the plasma processing apparatus 1 to etch a substrate having the same structure as that of Example 1. Figure 3 A substrate having the same structure as the substrate W shown in the figure is etched. As the mask MF, an amorphous carbon film is used. As the silicon-containing film SF, a stacked film formed by alternately and repeatedly stacking a silicon nitride film and a silicon oxide film is used. The first processing gas used in step ST21 contains HF gas, a phosphorus-containing gas, O2 gas and WE6 gas. The second processing gas used in step ST22 contains HF gas, a phosphorus-containing gas and O2 gas. The cycle of step ST21 (15 seconds) and step ST22 (45 seconds) is repeated for 15 cycles, and etching is performed for a total of 15 minutes. During etching, the temperature of the substrate support 11 is set to 10°C.

[0138] (Reference Example 3)

[0139] In Reference Example 3, a substrate having the same structure as that of Example 1 was etched using the plasma processing apparatus 1. In Reference Example 3, a cycle of etching (25 seconds) using C4F8 gas, C4F6 gas, CHF3 gas, CH2F2 gas, and O2 gas as processing gases and etching (50 seconds) using C4F8 gas, C4F6 gas, CH2F2 gas, O2 gas, and Kr gas as processing gases was repeated 14 times, and etching was performed for a total of 17.5 minutes. During etching, the temperature of the substrate support 11 was set to 10°C.

[0140] The etching depth: D [nm], curvature (maximum opening width): B [nm], the ratio of curvature (B) to etching depth (D): B / D and etching rate: E [nm / min] of the silicon-containing film SF after etching of Example 2 and Reference Example 3 are shown in Table 2.

[0141]

Table 2

[0142] Example 2 Reference Example 3 D[nm] 9181 6164 B[nm] 194.7 154.4 B / D 0.021 0.025 E[nm / min] 612.1 352.2

[0143] In Example 2, the etching rate is greatly improved compared to Reference Example 3. In addition, in Example 2, the ratio (B / D) of the bend (B) to the etching depth (D) is also lowered by the same amount or more than that of Reference Example 3, and the bend is suppressed. That is, in Example 2, the etching rate is greatly improved compared to Reference Example 3, and the bend is suppressed.

[0144] (Example 3)

[0145] In Example 3, the present processing method was applied using the plasma processing apparatus 1 to etch the substrate having the same structure as that of Example 1. The first processing gas used in step ST21 contained HF gas, phosphorus-containing gas, WE6 gas, halogen-containing gas, hydrofluorocarbon gas, and fluorocarbon gas. The second processing gas used in step ST22 was the same as the first processing gas except that it did not contain WE6 gas. In step ST2, step ST21 (20 seconds) and step ST22 (40 seconds) were repeated for 11 cycles, and etching was performed for a total of 11 minutes.

[0146] (Example 4)

[0147] Example 4 is the same as Example 3 except that a cycle of step ST21 (40 seconds) and step ST22 (20 seconds) is repeated in step ST2.

[0148] (Reference Example 4 and Reference Example 5)

[0149] In Reference Examples 4 and 5, the substrate having the same structure as that of Example 1 was etched using the plasma processing apparatus 1. In Reference Example 4, etching was performed for 11 minutes using the same processing gas as the second processing gas used in Example 3. In Reference Example 5, etching was performed for 11 minutes using the same processing gas as the first processing gas used in Example 1.

[0150] Table 3 shows the etching results of Example 3, Example 4, Reference Example 4, and Reference Example 5. In Table 3, D [nm] represents the etching depth of the silicon-containing film SF after etching. B [nm] represents the bend (maximum opening width). BT [nm] represents the bottom of the recess RC, specifically, the opening width at a depth of 5 μm from the boundary between the mask MF and the recess RC.

[0151]

Table 3

[0152] Example 3 Example 4 Reference Example 4 Reference Example 5 D[nm] 5346 5700 5234 5600 B[nm] 111 108 105 106 BT[nm] 61 56 38 45

[0153] As shown in Table 3, in Examples 3 and 4, the bottom opening width of the concave portion RC is wider than that of Reference Examples 4 and 5, and the top end is suppressed from tapering. In addition, the warping of Examples 3 and 4 is suppressed to the same extent as that of Reference Examples 4 and 5.

[0154] Figure 8 is a diagram showing the etching results of Example 3 and Reference Example 4. Figure 8 , (a1) and (b1) are diagrams showing the cross-sectional shapes of the bottoms of the concave portions RC after etching of Example 3 and Reference Example 4, respectively. (a2) and (b2) are diagrams showing the cross-sectional shapes of the concave portions RC after etching of Example 3 and Reference Example 4, respectively.

[0155] like Figure 8 As shown in (a1), in the etching of Example 3, the opening width of the bottom of the concave portion RC is not large, and the cross-sectional shape of the bottom is rectangular. Figure 8 As shown in (b1), in the etching of Reference Example 4, the opening width of the bottom of the concave portion RC is small, and the cross-sectional shape becomes thinner toward the bottom. Figure 8 As shown in (a2), in the etching of Example 3, the plurality of concave portions RC are etched in the depth direction, thereby suppressing bending and deviation. Figure 8 As shown in (b2), in the etching of Reference Example 4, bending and deviation occurred in some of the multiple recessed portions RC.

[0156] Fig. 9 The diagram shows the etching results of Example 3, Example 4, Reference Example 4, and Reference Example 5. Fig. 9The relationship between the duration of step ST21 and the offset caused by etching is shown. Fig. 9 In the figure, the vertical axis represents the offset σ[%] when the offset of the concave portion RC in reference example 4 is set to 100%. The horizontal axis represents the duration of step ST21 in one cycle (60 seconds) of step ST2 (since step ST21 is not performed in reference example 4, it is set to 0 seconds, and since only step ST21 is performed in reference example 5, it is set to 60 seconds).

[0157] like Fig. 9 As shown, the deviation in Examples 3, 4, and 5 is suppressed compared to that in Reference Example 4. In addition, the longer the duration of step ST21 in one cycle is, the more the deviation is suppressed.

[0158] The embodiments of the present disclosure also include the following aspects.

[0159] (Note 1)

[0160] A plasma processing method is a plasma processing method performed in a plasma processing device having a chamber, the plasma processing method comprising:

[0161] Step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; and

[0162] Step (b), etching the silicon-containing film,

[0163] Wherein, the step (b) comprises:

[0164] Step (b-1), etching the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and tungsten-containing gas; and

[0165] In step (b-2), the silicon-containing film is etched using plasma generated from a second process gas containing hydrogen fluoride gas, wherein the second process gas does not contain a tungsten-containing gas or contains a tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first process gas.

[0166] (Note 2)

[0167] In the plasma processing method described in Supplementary Note 1, in the step (b), the step (b-1) and the step (b-2) are performed alternately and repeatedly.

[0168] (Note 3)

[0169] In the plasma treatment method described in Supplement 1, in the step (b), a cycle including the step (b-1) and the step (b-2) is repeated a plurality of times,

[0170] In the step (b-1) of at least one of the cycles from the second time onward, a flow rate ratio of the tungsten-containing gas to the first processing gas is smaller than the flow rate ratio in the step (b-1) of the first cycle.

[0171] (Note 4)

[0172] In the plasma processing method described in any one of Appendix 1 to Appendix 3, at least one of the tungsten-containing gas contained in the first processing gas and the tungsten-containing gas contained in the second processing gas is WF a Cl b Gas, wherein a and b are each an integer greater than or equal to 0 and less than or equal to 6, and the sum of a and b is greater than or equal to 2 and less than or equal to 6.

[0173] (Note 5)

[0174] In the plasma processing method described in any one of Notes 1 to 4, at least one of the tungsten-containing gas contained in the first processing gas and the tungsten-containing gas contained in the second processing gas is at least one of WF6 gas and WCl6 gas.

[0175] (Note 6)

[0176] In the plasma processing method according to any one of Supplementary Notes 1 to 5, among the first processing gas, the flow rate of the hydrogen fluoride gas is the largest among all gases except the inert gas.

[0177] (Note 7)

[0178] In the plasma processing method described in any one of Supplementary Notes 1 to 6, among the first processing gas, the flow rate of the tungsten-containing gas is the smallest among all gases except the inert gas.

[0179] (Note 8)

[0180] In the plasma processing method described in any one of Supplementary Notes 1 to 7, in the first processing gas, a flow rate of the hydrogen fluoride gas is 10 times or more of a flow rate of the tungsten-containing gas.

[0181] (Note 9)

[0182] In the plasma processing method described in any one of Supplementary Notes 1 to 8, at least one of the first processing gas and the second processing gas further includes a phosphorus-containing gas.

[0183] (Note 10)

[0184] In the plasma processing method described in Supplementary Note 9, the phosphorus-containing gas is a phosphorus halide gas.

[0185] (Note 11)

[0186] In the plasma processing method described in any one of Supplementary Notes 1 to 10, at least one of the first processing gas and the second processing gas further includes a carbon-containing gas.

[0187] (Note 12)

[0188] In the plasma processing method according to Supplementary Note 11, the carbon-containing gas is any one of a fluorocarbon gas and a hydrofluorocarbon gas.

[0189] (Note 13)

[0190] In the plasma processing method described in any one of Supplementary Notes 1 to 12, at least one of the first processing gas and the second processing gas further includes an oxygen-containing gas.

[0191] (Note 14)

[0192] In the plasma processing method according to any one of Supplementary Notes 1 to 13, at least one of the first processing gas and the second processing gas further contains a gas containing a halogen other than fluorine.

[0193] (Note 15)

[0194] In the plasma processing method described in any one of Supplementary Notes 1 to 14, the mask has a hole pattern or a slit pattern.

[0195] (Note 16)

[0196] A plasma processing method is a plasma processing method performed in a plasma processing device having a chamber, the plasma processing method comprising:

[0197] Step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; and

[0198] Step (b), etching the silicon-containing film, wherein:

[0199] The step (b) comprises:

[0200] Step (b-1), etching the silicon-containing film using a first plasma containing a hydrogen fluoride species and a chemical species containing at least one of tungsten, titanium, and molybdenum; and

[0201] In step (b-2), the silicon-containing film is etched using a second plasma containing a hydrogen fluoride species, wherein the second plasma does not contain the chemical species or contains the chemical species at a partial pressure smaller than the partial pressure of the chemical species in the first plasma.

[0202] (Note 17)

[0203] In the plasma processing method described in Supplementary Note 16, in the step (b), the step (b-1) and the step (b-2) are performed alternately and repeatedly.

[0204] (Note 18)

[0205] In the plasma processing method according to Supplementary Note 16 or Supplementary Note 17, the hydrogen fluoride species is generated from at least one of hydrogen fluoride gas and hydrofluorocarbon gas.

[0206] (Note 19)

[0207] In the plasma processing method according to Supplementary Note 16 or Supplementary Note 17, the hydrogen fluoride species is generated from a hydrofluorocarbon gas having a carbon number of 2 or more.

[0208] (Note 20)

[0209] In the plasma processing method according to Supplementary Note 16 or Supplementary Note 17, the hydrogen fluoride species is generated from a fluorine-containing gas and a hydrogen-containing gas.

[0210] (Note 21)

[0211] In the plasma processing method described in any one of Supplementary Notes 16 to 20, at least one of the first plasma and the second plasma further contains a phosphorus-containing species.

[0212] (Note 22)

[0213] A plasma processing system includes a chamber, a substrate support portion disposed in the chamber, a plasma generating portion, and a control portion.

[0214] Wherein, the control unit executes:

[0215] Control (a) to provide a substrate having a silicon-containing film and a mask on the silicon-containing film onto the substrate support portion; and

[0216] controlling (b) to etch the silicon-containing film,

[0217] Wherein, the control (b) includes:

[0218] controlling (b-1) to etch the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and tungsten-containing gas; and

[0219] Control (b-2) to etch the silicon-containing film using plasma generated from a second process gas containing hydrogen fluoride gas, wherein the second process gas does not contain a tungsten-containing gas or contains a tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first process gas.

[0220] (Note 23)

[0221] A device manufacturing method is a device manufacturing method performed in a plasma processing apparatus having a chamber, the device manufacturing method comprising:

[0222] Step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; and

[0223] Step (b), etching the silicon-containing film,

[0224] Wherein, the step (b) comprises:

[0225] Step (b-1), etching the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and tungsten-containing gas; and

[0226] In step (b-2), the silicon-containing film is etched using plasma generated from a second process gas containing hydrogen fluoride gas, wherein the second process gas does not contain a tungsten-containing gas or contains a tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first process gas.

[0227] (Note 24)

[0228] A program causes a computer of a plasma processing system including a chamber, a substrate support unit provided in the chamber, and a plasma generating unit to execute the following control:

[0229] Control (a) to provide a substrate having a silicon-containing film and a mask on the silicon-containing film onto the substrate support portion; and

[0230] controlling (b) to etch the silicon-containing film,

[0231] Wherein, the control (b) includes:

[0232] controlling (b-1) to etch the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and tungsten-containing gas; and

[0233] Control (b-2) to etch the silicon-containing film using plasma generated from a second process gas containing hydrogen fluoride gas, wherein the second process gas does not contain a tungsten-containing gas or contains a tungsten-containing gas at a flow ratio smaller than the flow ratio of the tungsten-containing gas in the first process gas.

[0234] (Note 25)

[0235] A storage medium storing the program according to Appendix 24.

[0236] Description of Reference Numerals

[0237] 1: plasma processing device; 2: control unit; 10: plasma processing chamber; 10s: plasma processing space; 11: substrate support unit; 13: shower head; 20: gas supply unit; 31a: first RF generating unit; 31b: second RF generating unit; 32a: first DC generating unit; SF: silicon-containing film; MF: mask; OP: opening; PF: protective film; RC: recess; UF: base film; W: substrate.

Claims

1. A plasma processing method is a plasma processing method performed in a plasma processing device having a chamber, the plasma processing method comprising: Step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; as well as Step (b), etching the silicon-containing film, Wherein, the step (b) comprises: Step (b-1), etching the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and tungsten-containing gas; and step (b-2), etching the silicon-containing film using plasma generated from a second process gas containing hydrogen fluoride gas, the second process gas not containing a tungsten-containing gas or containing a tungsten-containing gas at a flow rate ratio smaller than the flow rate ratio of the tungsten-containing gas in the first process gas, In the step (b), the step (b-1) and the step (b-2) are performed alternately and repeatedly.

2. The plasma treatment method according to claim 1, characterized in that: In the step (b-1) of at least one of the cycles including the step (b-1) and the step (b-2) starting from the second time, the flow ratio of the tungsten-containing gas to the first processing gas is smaller than the flow ratio in the step (b-1) of the first cycle, or the time of the step (b-1) of at least one of the cycles starting from the second time is shorter than the time of the step (b-1) of the first cycle.

3. The plasma treatment method according to claim 1 or 2, characterized in that: At least one of the tungsten-containing gas contained in the first process gas and the tungsten-containing gas contained in the second process gas is WF a Cl b Gas, wherein a and b are each an integer greater than or equal to 0 and less than or equal to 6, and the sum of a and b is greater than or equal to 2 and less than or equal to 6.

4. The plasma treatment method according to claim 1 or 2, characterized in that: At least one of the tungsten-containing gas included in the first process gas and the tungsten-containing gas included in the second process gas is at least any one of WF6 gas and WCl6 gas.

5. The plasma treatment method according to claim 1 or 2, characterized in that: In the first process gas, the flow rate of the hydrogen fluoride gas is the largest among all gases except the inert gas.

6. The plasma treatment method according to claim 1 or 2, characterized in that: In the first process gas, the flow rate of the tungsten-containing gas is the smallest among all gases except the inert gas.

7. The plasma treatment method according to claim 1 or 2, characterized in that: In the first process gas, the flow rate of the hydrogen fluoride gas is 10 times or more than the flow rate of the tungsten-containing gas.

8. The plasma treatment method according to claim 1 or 2, characterized in that: At least one of the first process gas and the second process gas further includes a phosphorus-containing gas.

9. The plasma processing method according to claim 8, characterized in that: The phosphorus-containing gas is a phosphorus halide gas.

10. The plasma treatment method according to claim 1 or 2, characterized in that: At least one of the first process gas and the second process gas further includes a carbon-containing gas.

11. The plasma processing method according to claim 10, characterized in that: The carbon-containing gas is any one of a fluorocarbon gas and a hydrofluorocarbon gas.

12. The plasma treatment method according to claim 1 or 2, characterized in that: At least one of the first process gas and the second process gas further includes an oxygen-containing gas.

13. The plasma treatment method according to claim 1 or 2, characterized in that: At least one of the first process gas and the second process gas further includes a gas containing a halogen other than fluorine.

14. The plasma treatment method according to claim 1 or 2, characterized in that: The mask has a hole pattern or a slit pattern.

15. A plasma processing method, which is a plasma processing method performed in a plasma processing device having a chamber, the plasma processing method comprising: Step (a), providing a substrate having a silicon-containing film and a mask on the silicon-containing film; as well as Step (b), etching the silicon-containing film, wherein: The step (b) comprises: Step (b-1), etching the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and tungsten-containing gas; and step (b-2), etching the silicon-containing film using plasma generated from a second process gas containing hydrogen fluoride gas, the second process gas not containing a tungsten-containing gas or containing a tungsten-containing gas at a partial pressure smaller than the partial pressure of the tungsten-containing gas in the first process gas, In the step (b), the step (b-1) and the step (b-2) are performed alternately and repeatedly.

16. A plasma processing system comprising a chamber, a substrate support portion provided in the chamber, a plasma generating portion, and a control portion, in, The control unit performs: Control (a) to provide a substrate having a silicon-containing film and a mask on the silicon-containing film on the substrate support portion; as well as controlling (b) to etch the silicon-containing film, Wherein, the control (b) comprises: controlling (b-1) to etch the silicon-containing film using plasma generated from a first process gas containing hydrogen fluoride gas and tungsten-containing gas; and controlling (b-2) to etch the silicon-containing film using plasma generated from a second process gas containing hydrogen fluoride gas, the second process gas not containing a tungsten-containing gas or containing a tungsten-containing gas at a flow rate ratio smaller than the flow rate ratio of the tungsten-containing gas in the first process gas, In the control (b), the control (b-1) and the control (b-2) are performed alternately and repeatedly.

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