Plasma processing method and plasma processing system

Abstract

To provide a technique of increasing a selection ratio to a mask film.SOLUTION: There is provided a plasma processing method executed in a plasma processing device having a chamber. The method includes: a step (a) of providing a substrate having an organic film and a mask film formed on the organic film into a chamber, the mask film including a silicon-containing film and a carbon-containing film formed on the silicon-containing film; and a step (b) of generating plasma from process gas containing oxygen-containing gas and gas containing Si or W and halogen in the chamber. The step (b) includes: a step (b1) of forming a protection film on at least the carbon-containing film of the mask film; and a step (b2) of etching the organic film via the mask film formed with the protection film.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] SUMMARY OF THE INVENTION 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 silicon-containing film. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-109373 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides a technique for increasing the selectivity to a mask film. [Means for solving the problem]

[0005] In one exemplary embodiment of the present disclosure, there is provided a plasma processing method that is performed in a plasma processing apparatus having a chamber, the plasma processing method including: (a) providing a substrate having an organic film and a mask film formed on the organic film into the chamber, where the mask film includes a silicon-containing film and a carbon-containing film formed on the silicon-containing film; and (b) generating plasma in the chamber from a process gas that includes an oxygen-containing gas and a gas containing Si or W and a halogen, wherein (b) includes: (b1) forming a protective film on at least the carbon-containing film of the mask film; and (b2) etching the organic film through the mask film on which the protective film is formed. [Effects of the Invention]

[0006] According to one exemplary embodiment of the present disclosure, a technique for increasing the selectivity to a mask film 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 showing the present processing method. [Figure 3] 2 is a diagram schematically illustrating an example of a cross-sectional structure of a substrate W provided in step ST1. FIG. [Figure 4] 10 is a diagram schematically showing an example of a cross-sectional structure of the substrate W immediately after the start of step ST3. FIG. [Figure 5] 10 is a diagram schematically showing an example of the cross-sectional structure of the substrate W being processed in step ST3. FIG. [Figure 6] FIG. 10 is a diagram schematically showing another example of the cross-sectional structure of the substrate W being processed in step ST3. [Figure 7] FIG. 2 is a diagram illustrating an example of a substrate according to an embodiment. [Figure 8] FIG. 10 is a diagram schematically showing an example of a cross-sectional structure of a substrate W′ according to a modified 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 method performed in a plasma processing apparatus having a chamber, the plasma processing method comprising: (a) providing a substrate having an organic film and a mask film formed on the organic film into the chamber, where the mask film includes a silicon-containing film and a carbon-containing film formed on the silicon-containing film; and (b) generating plasma in the chamber from a process gas including an oxygen-containing gas and a gas containing Si or W and a halogen, wherein (b) includes: (b1) forming a protective film on at least the carbon-containing film of the mask film; and (b2) etching the organic film through the mask film on which the protective film has been formed.

[0010] In one exemplary embodiment, the gas containing Si or W and a halogen includes at least SiCl4.

[0011] In one exemplary embodiment, the gas containing Si or W and a halogen includes at least WF6.

[0012] In one exemplary embodiment, the protective coating comprises silicon or tungsten.

[0013] In one exemplary embodiment, the silicon-containing film is a SiON film.

[0014] In one exemplary embodiment, the carbon-containing film is a SOC film or a BARC film.

[0015] In one exemplary embodiment, the oxygen-containing gas comprises at least one selected from the group consisting of O2, O3, CO, CO2, and H2O.

[0016] In one exemplary embodiment, the process gas comprises a sulfur-containing gas.

[0017] In one exemplary embodiment, the sulfur-containing gas comprises COS or SO2.

[0018] In one exemplary embodiment, the process gas further comprises a halogen-containing gas.

[0019] In one exemplary embodiment, there is provided a plasma processing method performed in a plasma processing apparatus having a chamber, the method comprising: (a) providing a substrate having an organic film and a mask film formed on the organic film and including a carbon-containing film into the chamber; and (b) generating plasma in the chamber from a processing gas including an oxygen-containing gas and a gas containing Si or W and a halogen, wherein (b) includes: (b1) forming a protective film on at least the carbon-containing film of the mask film; and (b2) etching the organic film through the mask film on which the protective film has been formed.

[0020] In one exemplary embodiment, there is provided a plasma processing method performed in a plasma processing apparatus having a chamber, the method including: (a) providing a substrate having a mask film including an organic film, a silicon-containing film on the organic film, and a carbon-containing film formed on the silicon-containing film into the chamber; and (b) supplying a process gas including an oxygen-containing gas and a first halogen-containing gas containing Si or W and a halogen into the chamber to generate plasma and etch the organic film through the mask film, wherein the flow rate of the gas containing Si or W and the halogen with respect to the total flow rate of the process gas is less than 5% by volume.

[0021] In one exemplary embodiment, there is provided a plasma processing system including a chamber, a substrate support, a process gas supply unit, and a controller, wherein the controller (a) provides a substrate having an organic film and a mask film formed on the organic film on the substrate support in the chamber, the mask film including a silicon-containing film and a carbon-containing film formed on the silicon-containing film; (b) supplies a process gas including an oxygen-containing gas and a gas containing Si or W and a halogen into the chamber by the process gas supply unit to generate plasma, and (b) performs control to (b1) form a protective film on at least the carbon-containing film of the mask film, and (b2) etch the organic film through the mask film on which the protective film has been formed.

[0022] <Configuration example of plasma processing system> An example of the configuration of a plasma processing system will be described below: Figure 1 is a schematic diagram of an exemplary plasma processing system.

[0023] The plasma processing system includes an inductively coupled plasma processing apparatus 1 and a control unit 2. The inductively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing chamber 10 includes a dielectric window. The plasma processing apparatus 1 also includes a substrate support 11, a gas inlet, and an antenna 14. The substrate support 11 is disposed within the plasma processing chamber 10. The antenna 14 is disposed on or above the plasma processing chamber 10 (i.e., on or above the dielectric window 101). The plasma processing chamber 10 has a plasma processing space 10s defined by the dielectric window 101, a sidewall 102 of the plasma processing chamber 10, and the substrate support 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. The plasma processing chamber 10 is grounded.

[0024] 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 ring assembly 112.

[0025] 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 bias 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. Furthermore, at least one RF / DC electrode coupled to an RF (Radio Frequency) power supply 31 and / or a DC (Direct Current) power supply 32 (described later) may be disposed within the ceramic member 1111a. In this case, the at least one RF / DC electrode functions as a bias electrode. Note that the conductive member of the base 1110 and the at least one RF / DC electrode may function as multiple bias electrodes. Alternatively, the electrostatic electrode 1111b may function as a bias electrode. Therefore, the substrate support 11 includes at least one bias electrode.

[0026] 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.

[0027] 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 passage 1110a, or a combination thereof. A heat transfer fluid such as brine or a gas flows through the flow passage 1110a. In one embodiment, the flow passage 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 to a gap between the backside of the substrate W and the central region 111a.

[0028] The gas inlet is configured to introduce at least one process gas from the gas supply unit 20 into the plasma processing space 10s. In one embodiment, the gas inlet includes a center gas injector (CGI) 13. The center gas injector 13 is disposed above the substrate support 11 and attached to a central opening formed in the dielectric window 101. The center gas injector 13 has at least one gas supply port 13a, at least one gas flow path 13b, and at least one gas inlet port 13c. The process gas supplied to the gas supply port 13a passes through the gas flow path 13b and is introduced into the plasma processing space 10s from the gas inlet port 13c. Note that the gas inlet may include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 102 in addition to or instead of the center gas injector 13.

[0029] 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 gas inlet through 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.

[0030] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power) to at least one bias electrode and the antenna 14. This causes a plasma to be 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 a plasma from one or more processing gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the at least one bias electrode, a bias potential is generated on the substrate W, thereby attracting ions in the formed plasma to the substrate W.

[0031] 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 the antenna 14 and configured to generate a source RF signal (source RF power) for plasma generation via at least one impedance matching circuit. 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 the antenna 14.

[0032] The second RF generating unit 31b is coupled to at least one bias 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 bias electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0033] 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 bias DC generator 32a. In one embodiment, the bias DC generator 32a is connected to at least one bias electrode and configured to generate a bias DC signal. The generated bias DC signal is applied to the at least one bias electrode.

[0034] In various embodiments, the bias DC signal may be pulsed. In this case, a sequence of voltage pulses is applied to at least one bias electrode. The voltage pulses may have a rectangular, trapezoidal, triangular, or combination thereof. In one embodiment, a waveform generator for generating the sequence of voltage pulses from the DC signal is connected between the bias DC generator 32a and at least one bias electrode. Therefore, the bias DC generator 32a and the waveform generator constitute a voltage pulse generator. 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 cycle. Note that the bias DC generator 32a may be provided in addition to the RF power supply 31 or may be provided instead of the second RF generator 31b.

[0035] The antenna 14 includes one or more coils. In one embodiment, the antenna 14 may include an outer coil and an inner coil arranged coaxially. In this case, the RF power supply 31 may be connected to both the outer coil and the inner coil, or to either the outer coil or the inner coil. In the former case, the same RF generator may be connected to both the outer coil and the inner coil, or separate RF generators may be connected to the outer coil and the inner coil separately.

[0036] 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.

[0037] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in this disclosure. The control unit 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 control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 may be implemented by, for example, a computer 2a. 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 processing unit 2a1 may be a CPU (Central Processing Unit). 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).

[0038] 2 is a flowchart showing a plasma processing method (hereinafter also referred to as "this processing method") according to an example embodiment. 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 control unit 2 controls each part of the plasma processing apparatus 1 to perform this processing method on a substrate W. FIG. 2 includes a step ST1 of providing a substrate W, a step ST2 of supplying a processing gas, and a step ST3 of generating plasma.

[0039] (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 provided on the upper surface of the substrate support 11 and is held on the substrate support 11 by the electrostatic chuck 1111.

[0040] 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 stacked in this order on an undercoat film UF. The mask film MF may be formed of multiple layers, for example, two layers consisting of a silicon-containing film SF and a carbon-containing film CF. The substrate W may be used in the manufacture of semiconductor devices, including semiconductor memory devices such as DRAMs and 3D-NAND flash memories.

[0041] 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, or the like. The base film UF may be formed by stacking multiple films. For example, the base film UF may be formed by alternately stacking silicon oxide films and polycrystalline silicon films, or silicon oxide films and silicon nitride films.

[0042] The etching target film EF is an organic film, and may be, for example, an SOC (Spin On Carbon) film, an ACL (Amorphous Carbon Layer) film, or the like.

[0043] The substrate W may further have another film below the underlayer film UF, and the stacked film of the etching target film EF and the underlayer film UF may function as a multilayer mask. That is, the stacked film of the etching target film EF and the underlayer film UF may be used as a multilayer mask to etch the other film.

[0044] The mask film MF is formed on the upper surface of the etching target film EF. In one exemplary embodiment, the mask film MF may be composed of two layers: a silicon-containing film SF and a carbon-containing film CF formed on the silicon-containing film SF. As will be described later, the mask film MF may be composed of a single layer of the carbon-containing film CF.

[0045] The silicon-containing film SF may be any film containing Si, such as a silicon oxide film, a silicon nitride film, a silicon oxynitride film (SiON film), a BSi film, a WSi film, or a Si-ARC (Silicon-Anti Reflection Coating) film.

[0046] The carbon-containing film CF may be any film containing carbon, such as an SOC film or a BARC (Bottom Anti-Reflection Coating) film.

[0047] As shown in FIG. 3, the mask film MF has at least one opening OP. The opening OP is defined by the side surface ss of the mask film. The opening OP is a space on the etching target film EF that is surrounded by the side surface ss of the mask film. That is, in FIG. 3, the upper surface of the etching target film EF has a portion covered by the mask film MF and a portion exposed by the opening OP. The opening OP may have any shape in a plan view of the substrate W (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 openings OP. Each of the multiple openings OP may have a hole shape and may form an array pattern arranged at regular intervals. Alternatively, each of the multiple openings OP may have a linear shape and be arranged at regular intervals to form a line-and-space pattern. Each of the films constituting the substrate W (base film UF, etching target film EF, mask film MF) may be formed by a CVD (Chemical Vapor Deposition) method, an ALD (Atomic Layer Deposition) method, a spin coating method, or the like. Each of the above films may be a flat film or may have an uneven surface. The opening OP in the mask film MF may be formed by etching the mask film MF.

[0048] At least a part of the process of forming each film on the substrate W may be performed within the space of 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 within the same chamber. Alternatively, after all or part of each film on 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 and placed on the upper surface of the substrate support 11, thereby providing the substrate.

[0049] (Step ST2: Supply of processing gas) In step ST2, a processing gas is supplied from the gas supply unit 20 to the plasma internal space 10s.

[0050] The processing gas includes an oxygen-containing gas and a gas containing Si or W and a halogen (hereinafter also referred to as "Si / W gas" in this specification). The oxygen-containing gas includes at least one gas selected from the group consisting of O gas, CO gas, and CO gas.

[0051] The Si / W gas may include at least one selected from the group consisting of SiF4 gas, SiCl4 gas, WF6 gas, and WCl4 gas, and the flow rate of the Si / W gas may be less than 5% by volume with respect to the total flow rate of the process gas.

[0052] The process gas may further include a sulfur-containing gas. The sulfur-containing gas may include at least one selected from the group consisting of COS and SF6.

[0053] The process gas may further include a halogen-containing gas other than the Si / W gas, which may be at least one selected from the group consisting of CHF3 gas, CF4 gas, NF3 gas, SF6 gas, IF7 gas, HF gas, HBr gas, Cl2 gas, BCl3 gas, and Br2 gas.

[0054] (Step ST3: Plasma generation) In step ST3, plasma is generated from the processing gas supplied into the plasma processing space 10s.

[0055] FIG. 4 is a diagram schematically illustrating an example of the cross-sectional structure of the substrate W immediately after the start of step ST3. In this processing method, Si or W in the Si / W gas dissociates in the plasma and deposits on the upper surface ts and side surface ss1 of the carbon-containing film CF. This results in the formation of a protective film PF on the carbon-containing film CF. As shown in FIG. 4, the thickness of the protective film PF formed on the side surface ss1 of the carbon-containing film CF is thinner than the thickness of the protective film PF formed on the upper surface ts. This is thought to be because the Si or W in the plasma is deposited anisotropically on the carbon-containing film CF. Note that, according to experiments conducted by the present inventors, such anisotropic deposition was not observed when the mask film MF was formed solely of the silicon-containing film SF. The Si or W in the plasma is isotropically deposited on the silicon-containing film SF, and a protective film of the same thickness as that on the upper surface was also formed on the side surface of the silicon-containing film SF.

[0056] The protective film PF contains Si or W or an oxide thereof. The protective film PF has lower reactivity with activated oxygen species in the plasma than the carbon-containing film CF. The protective film prevents the carbon-containing film CF from being etched by activated oxygen species in the plasma during step ST3. The protective film PF may also be formed on the side surface ss2 of the silicon-containing film. That is, the protective film may be formed over the entire side surface ss of the mask film MF.

[0057] FIG. 5 is a schematic diagram illustrating an example of the cross-sectional structure of a substrate W during process ST3. During process ST3, oxygen radicals in the plasma are attracted to the substrate W, causing etching of the target film EF. That is, a portion of the target film EF corresponding to the opening OP in the mask film MF is etched in the depth direction (from top to bottom in the figure), forming a recess. During process ST3, the protective film PF may be removed to some extent due to collisions with ions in the plasma. However, since Si or W deposition continues simultaneously, the protective film PF is not completely removed during process ST3. During process ST3, the flow rate of the Si / W gas may be constant or may not be constant. For example, the flow rate of the Si / W gas may be reduced after a certain time has elapsed since the start of process ST3. The flow rate of the Si / W gas needs to be sufficient to form the protective film PF immediately after the start of process ST3, but after a certain time has elapsed, a flow rate sufficient to compensate for the reduction in the protective film PF is sufficient.

[0058] According to this processing method, a protective film PF is formed on the carbon-containing film CF immediately after the start of step ST3. As described above, the protective film PF can prevent the carbon-containing film CF from being etched by activated oxygen species in the plasma during step ST3. If the carbon-containing film CF remains unremoved during step ST3, the underlying silicon-containing film SF will also remain. That is, according to this processing method, the selectivity to the mask film MF can be significantly improved.

[0059] As described above, the thickness of the protective film PF formed on the side surface ss1 of the carbon-containing film CF is thinner than the thickness of the protective film PF formed on the upper surface ts. This prevents the protective film PF from being deposited on the side surface ss1 of the carbon-containing film CF, thereby preventing the width of the opening OP from narrowing. This in turn prevents shape abnormalities (such as bowing or tapering) in the recess formed in the etching target film EF.

[0060] 6 is a diagram schematically illustrating another example of the cross-sectional structure of the substrate W during processing in step ST3. As shown in FIG. 6, the carbon-containing film CF may gradually shrink inward in the width direction (left-right direction in the figure) during execution of step ST3. In this case, the protective film PF is formed along the carbon-containing film CF that has shrunk in the width direction, and therefore, the protective film PF is further prevented from protruding in the width direction. This prevents the width of the opening OP from narrowing, and therefore prevents abnormal shapes of recesses formed in the etching target film EF.

[0061] <Example> Next, examples of the present processing method will be described, but the present disclosure is not limited to the following examples.

[0062] FIG. 7 is a diagram depicting an example of a substrate according to Examples 1 to 3. In Examples 1 to 3, the present processing method was applied using a plasma processing apparatus 1 to etch an etching target film EF on a substrate W. Polysilicon was used as the base film UF of the substrate W, and an ACL film was used as the etching target film EF. The mask film MF was formed of two layers: a silicon-containing film SF and a carbon-containing film CF, with a SiON film used as the silicon-containing film SF and a BARC film used as the carbon-containing film CF. In Examples 1 to 3, O2 gas, SiCl4 gas, and Cl2 gas were used as processing gases. In Examples 1 to 3, the flow rate ratio of SiCl4 gas to the total flow rate of the processing gas was 4 vol%, 6 vol%, and 8 vol%, respectively.

[0063] 7A to 7C are diagrams depicting the cross-sectional structure of the etching target film EF after etching in Examples 1 to 3, respectively. As shown in FIG. 7, the lower the flow rate ratio of SiCl4 gas to the total flow rate of the processing gas, the less the recesses formed in the etching target film EF by etching tapered, and the wider the bottom surface of the recesses (W A >W B >W C) In other words, the verticality of the recesses formed by etching was improved. This is thought to be because the flow rate of SiCl4 gas, which contributes to the formation of the protective film PF, was low, which reduced the amount of protective film PF deposited on the side surface ss of the mask film MF, thereby further suppressing the blockage of the mask film MF.

[0064] <Another example of this processing method> The present processing method may be subject to various modifications without departing from the scope and spirit of the present disclosure.

[0065] 8 is a diagram schematically illustrating an example of the cross-sectional structure of a substrate W' according to a modified example. The substrate W' differs from the substrate W in FIG. 3 in that the mask film MF is composed of a single carbon-containing film CF. Even when this substrate W' is used, the protective film PF is formed on the carbon-containing film CF immediately after the start of step ST3, so that the carbon-containing film CF can function sufficiently as a mask during the execution of step ST3.

[0066] Furthermore, for example, a de-clogging step of widening the opening width of the opening OP may be performed one or more times during the execution of step ST3. Specifically, a processing gas containing, for example, H gas and NF gas may be supplied into the plasma processing space 10s to generate plasma, and a portion of the protective film PF formed on the side surface ss1 of the carbon-containing film CF may be removed. This prevents the protective film PF from extending in the width direction during the execution of step ST3, i.e., prevents the width of the opening OP from narrowing. Consequently, abnormal shapes of recesses formed in the etching target film EF may be suppressed.

[0067] Furthermore, for example, this processing method may be performed using a plasma processing apparatus using any plasma source, such as a capacitively coupled plasma or microwave plasma, other than the inductively coupled plasma processing apparatus 1. [Explanation of symbols]

[0068] 1: Plasma processing apparatus, 2: Control unit, 10: Plasma processing chamber, 10s: Plasma processing space, 11: Substrate support unit, 20: Gas supply unit, PF: Protective film, MF: Mask film, CF: Carbon-containing film, SF: Silicon-containing film, EF: Film to be etched, UF: Undercoat film, W, W': Substrate, OP: Opening, ts: Top surface of carbon-containing film (top surface of mask film), ss: Side surface of mask film, ss1: Side surface of carbon-containing film, ss2: Side surface of silicon-containing film

Claims

1. A plasma processing method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having an organic film and a mask film formed on the organic film into a chamber, the mask film including a silicon-containing film and a carbon-containing film formed on the silicon-containing film; (b) generating a plasma in the chamber from a process gas including an oxygen-containing gas and a gas containing Si or W and a halogen; The (b) is (b1) forming a protective film on at least the carbon-containing film of the mask film; (b2) etching the organic film through the mask film on which the protective film is formed, the gas containing Si or W and a halogen contains at least SiCl 4 ; The plasma processing method, wherein the processing gas further includes a sulfur-containing gas.

2. The gas containing Si or W and a halogen is WF 6 The plasma processing method of claim 1 , further comprising:

3. The plasma processing method according to claim 1 , wherein the protective film contains silicon or tungsten.

4. The plasma processing method according to claim 1 , wherein the silicon-containing film is a SiON film.

5. The plasma processing method according to claim 1 , wherein the carbon-containing film is an SOC film or a BARC film.

6. The oxygen-containing gas is O 2 , O 3 , CO, CO 2 and H 2 The plasma processing method according to claim 1 , wherein the plasma processing method further comprises at least one selected from the group consisting of O.

7. The sulfur-containing gas is COS or SO 2 The plasma processing method according to claim 1 , comprising:

8. The plasma processing method of claim 1 , wherein the processing gas further contains a halogen-containing gas.

9. A plasma processing method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having an organic film and a mask film formed on the organic film into a chamber, the mask film comprising a carbon-containing film; (b) generating a plasma in the chamber from a process gas including an oxygen-containing gas and a gas containing Si or W and a halogen; The (b) is (b1) forming a protective film on at least the carbon-containing film of the mask film; (b2) etching the organic film through the mask film on which the protective film is formed, the gas containing Si or W and a halogen contains at least SiCl 4 ; The plasma processing method, wherein the processing gas further includes a sulfur-containing gas.

10. A plasma processing method performed in a plasma processing apparatus having a chamber, comprising: (a) providing a substrate having an organic film and a mask film formed on the organic film into a chamber, the mask film including a silicon-containing film and a carbon-containing film formed on the silicon-containing film; (b) supplying a process gas containing an oxygen-containing gas and a gas containing Si or W and a halogen into the chamber to generate plasma, and etching the organic film through the mask film; the flow rate of the gas containing Si or W and a halogen is less than 5% by volume with respect to the total flow rate of the processing gas; the gas containing Si or W and a halogen contains at least SiCl 4 ; The plasma processing method, wherein the processing gas further includes a sulfur-containing gas.

11. a chamber, a substrate support, a process gas supply and a control unit; The control unit (a) providing a substrate on the substrate support in the chamber, the substrate having an organic film and a mask film formed on the organic film, the mask film including a silicon-containing film and a carbon-containing film formed on the silicon-containing film; (b) supplying a processing gas containing an oxygen-containing gas and a gas containing Si or W and a halogen into the chamber by the processing gas supply unit to generate plasma; The (b) is (b1) forming a protective film on at least the carbon-containing film of the mask film; (b2) performing control to etch the organic film through the mask film on which the protective film is formed; the gas containing Si or W and a halogen contains at least SiCl 4 ; The process gas further comprises a sulfur-containing gas. Plasma treatment system.

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