Substrate processing method and substrate processing system

Abstract

The present disclosure provides a technique for improving an etching shape of a film to be etched, including: (a) a step of providing a substrate including the film to be etched and a mask on the film to be etched, the mask including a sidewall defining at least one opening; (b) a step for selectively forming an additional mask containing carbon on the mask using plasma generated from a processing gas containing carbon and hydrogen; and (c) a step for etching the film to be etched using plasma generated by the etching gas.

Description

Technical Field

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

[0002] A technique for etching a stacked film of a silicon-containing film is disclosed in Patent Document 1.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2021-118304 Summary of the Invention

[0006] The present disclosure provides a technique for improving the etching shape of a film to be etched.

[0007] A substrate processing method in an exemplary embodiment of the present disclosure includes: (a) a step of providing a substrate including a film to be etched and a mask on the film to be etched, the mask including sidewalls defining at least one opening; (b) a step of selectively forming a carbon-containing additional mask on the mask using a plasma generated from a processing gas containing carbon and hydrogen; and (c) a step of etching the film to be etched using a plasma generated from an etching gas.

[0008] Advantages of the Invention

[0009] According to an exemplary embodiment of the present disclosure, a technique for improving the etching shape of a film to be etched can be provided. Brief Description of the Drawings

[0010] Figure 1 is a diagram for explaining a configuration example of a plasma processing system.

[0011] Figure 2 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0012] Figure 3 is a diagram for explaining a configuration example of a substrate processing system.

[0013] Figure 4 is a flowchart showing an example of a substrate processing method according to the first embodiment.

[0014] Figure 5 is a diagram for explaining a structural example of a substrate W in step ST1.

[0015] Figure 6 is a diagram for explaining a structural example of a substrate W in step ST2.

[0016] Figure 7This is a diagram for explaining the structural example of the substrate W in the process ST3.

[0017] Figure 8 This is a flowchart showing an example of a method for forming a mask by plasma etching.

[0018] Figure 9 This is a diagram for explaining the structural example of the substrate W in the process ST0-1.

[0019] Figure 10 This is a diagram for explaining the structural example of the substrate W in the process ST0-2.

[0020] Figure 11 This is a diagram for explaining the structural example of the substrate W in the process ST0-2.

[0021] Figure 12 This is a flowchart showing an example of a substrate processing method including the process ST4.

[0022] Figure 13 This is a flowchart showing an example of a substrate processing method when performing multiple cycles including the processes ST2 and ST3.

[0023] Figure 14 This is a diagram for explaining the structural example of the substrate W in the process ST3.

[0024] Figure 15 This is a diagram for explaining the structural example of the substrate W in the second process ST2.

[0025] Figure 16 This is a flowchart showing an example of a substrate processing method according to the second embodiment.

[0026] Figure 17 This is a diagram for explaining the structural example of the substrate W in the first process ST3.

[0027] Figure 18 This is a diagram for explaining the structural example of the substrate W in the process ST2.

[0028] Figure 19 This is a diagram for explaining the structural example of the substrate W in the second process ST3.

[0029] Explanation of reference numerals

[0030] 1... Plasma processing apparatus; 2... Control unit; 10... Plasma processing chamber; 11... Substrate support part; 12... Plasma generation part; MK... Mask; OP1... Opening; U1... Upper surface; S1... Side wall; SF... Stacked film; UF... Bottom film; MK1... Additional mask; W... Substrate. Detailed description of the invention

[0031] Hereinafter, each embodiment of the present disclosure will be described.

[0032] In one exemplary embodiment, a substrate processing method is provided, including: (a) a step of providing a substrate including an etching target film and a mask on the etching target film, the mask including sidewalls defining at least one opening; (b) a step of selectively forming a carbon-containing additional mask on the mask using a plasma generated from a processing gas containing carbon and hydrogen; and (c) a step of etching the etching target film using a plasma generated from an etching gas.

[0033] In one exemplary embodiment, step (b) is performed after step (a).

[0034] In one exemplary embodiment, the substrate in step (a) includes a first film on the mask, and the substrate processing method further includes (d) a step of removing the first film between step (a) and step (b).

[0035] In one exemplary embodiment, multiple cycles are performed, and each cycle sequentially includes step (b) and step (c).

[0036] In one exemplary embodiment, step (c) is performed after step (a), and then one or more cycles sequentially including step (b) and step (c) are executed.

[0037] In one exemplary embodiment, the mask has a thickness of 10 μm or less.

[0038] In one exemplary embodiment, the mask includes at least one selected from the group consisting of a carbon-containing film, a silicon-containing film, and a metal-containing film.

[0039] In one exemplary embodiment, the additional mask has a thickness of 0.2 μm or more.

[0040] In one exemplary embodiment, the additional mask has a thickness of 2 μm or less.

[0041] In one exemplary embodiment, the additional mask includes an amorphous carbon film.

[0042] In one exemplary embodiment, the etching target film includes a stacked film including two or more different silicon-containing films.

[0043] In one exemplary embodiment, the etching target film includes a stacked film in which a silicon oxide film and a silicon nitride film are alternately stacked.

[0044] In one exemplary embodiment, the opening of the mask is formed by plasma etching.

[0045] In an exemplary embodiment, a substrate processing system is provided, which includes a substrate support portion, a plasma generation portion, and a control portion disposed in a chamber. The control portion performs: (a) control to supply a substrate including an etching target film and a mask on the etching target film to the substrate support portion, the mask including sidewalls defining at least one opening; (b) control to generate a plasma from a processing gas containing carbon and hydrogen by the plasma generation portion and selectively form an additional carbon-containing mask on the mask; and (c) control to generate a plasma from an etching gas by the plasma generation portion and etch the etching target film.

[0046] In an exemplary embodiment, the substrate processing system includes a plurality of chambers and a transfer module capable of transferring a substrate to the plurality of chambers in a vacuum environment. The control portion uses any one of the plurality of chambers to perform the controls of (a), (b), and (c) while maintaining the vacuum environment.

[0047] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In addition, the same or similar elements are denoted by the same reference numerals in each drawing, and repeated descriptions are omitted. Unless otherwise specified, the positional relationships such as up, down, left, and right are described based on the positional relationships shown in the drawings. The dimensional ratios of the drawings do not represent actual ratios, and furthermore, the actual ratios are not limited to the ratios shown in the drawings.

[0048] <An example of a plasma processing system>

[0049] Figure 1 This is a diagram for explaining a configuration example of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing apparatus 1 and a control portion 2. The plasma processing system is an example of a substrate processing system, and the plasma processing apparatus 1 is an example of a substrate processing apparatus. The plasma processing apparatus 1 includes a plasma processing chamber 10, a substrate support portion 11, and a plasma generation portion 12. The plasma processing chamber 10 has a plasma processing space. In addition, the plasma processing chamber 10 has at least one gas supply port for supplying at least one processing gas to the plasma processing space and at least one gas discharge port for discharging gas from the plasma processing space. The gas supply port is connected to a gas supply portion 20 described later, and the gas discharge port is connected to an exhaust system 40 described later. The substrate support portion 11 is disposed in the plasma processing space and has a substrate support surface for supporting a substrate.

[0050] The plasma generation unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may also be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), ECR plasma (Electron-Cyclotron-Resonance Plasma), helicon wave plasma (HWP), or surface wave plasma (SWP), etc. In addition, various types of plasma generation units including an alternating current (AC) plasma generation unit and a direct current (DC) plasma generation unit may also be used. In one embodiment, the alternating current signal (alternating current power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Therefore, the alternating current signal includes a radio frequency (RF) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

[0051] The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform various processes described in the present disclosure. The control unit 2 can be configured to control each element of the plasma processing apparatus 1 in a manner that executes the various processes described herein. In one embodiment, part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include a processing unit 2a1, a storage unit 2a2, and a communication interface 2a3. The control unit 2 is implemented, for example, by a computer 2a. The processing unit 2a1 can be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. The program may be pre-stored in the storage unit 2a2, and when needed, it may also be acquired via a medium. The acquired program is stored in the storage unit 2a2 and is read and executed by the processing unit 2a1 from the storage unit 2a2. The medium can 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 RAM (Random Access Memory), a ROM (Read Only Memory), an HDD (Hard Disk Drive), an SSD (Solid State Drive), or a combination thereof. The communication interface 2a3 can communicate with the plasma processing apparatus 1 via a communication line such as a LAN (Local Area Network).

[0052] A configuration example of a capacitively coupled plasma processing apparatus, which is an example of the plasma processing apparatus 1, will be described below. Figure 2 It is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

[0053] The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10 (also simply referred to as "chamber"), a gas supply unit 20, a power supply 30, and an exhaust system 40. In addition, the plasma processing apparatus 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 showerhead 13. The substrate support unit 11 is disposed inside the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support unit 11. In one embodiment, the showerhead 13 forms at least a part of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, the side wall 10a of the plasma processing chamber 10, the bottom wall 10b, and the substrate support unit 11. The plasma processing chamber 10 is grounded. The showerhead 13 and the substrate support unit 11 are electrically insulated from the frame of the plasma processing chamber 10.

[0054] The substrate support portion 11 includes a main body portion 111 and a ring assembly 112. The main body portion 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of the substrate W. The annular region 111b of the main body portion 111 surrounds the central region 111a of the main body portion 111 in a top view. The substrate W is disposed on the central region 111a of the main body portion 111, and the ring assembly 112 is disposed on the annular region 111b of the main body portion 111 so as to surround the substrate W on the central region 111a of the main body portion 111. Therefore, the central region 111a is also referred to as a substrate support surface for supporting the substrate W, and the annular region 111b is also referred to as a ring support surface for supporting the ring assembly 112.

[0055] In one embodiment, the main body portion 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Further, it may be an annular electrostatic chuck or other components such as an annular insulating member that surrounds the electrostatic chuck 1111 and has an annular region 111b. In this case, the ring assembly 112 can be disposed on the annular electrostatic chuck or the annular insulating member, or can be disposed on both the electrostatic chuck 1111 and the annular insulating member. Further, at least one RF / DC electrode coupled to the RF power supply 31 and / or the DC power supply 32 described later can also be disposed within the ceramic member 1111a. In this case, at least one RF / DC electrode functions as a lower electrode. When the bias RF signal and / or the DC signal described later are supplied to at least one RF / DC electrode, the RF / DC electrode is also referred to as a bias electrode. Further, the conductive member of the base 1110 and at least one RF / DC electrode can also function as a plurality of lower electrodes. Further, the electrostatic electrode 1111b can also function as a lower electrode. Therefore, the substrate support portion 11 includes at least one lower electrode.

[0056] 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 ring is formed of a conductive material or an insulating material, and the cover ring is formed of an insulating material.

[0057] In addition, the substrate support portion 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck 1111, the ring assembly 112, and the substrate to a target temperature. The temperature control module may also include a heater, a heat transfer medium, a flow path 1110a, or a combination thereof. In the flow path 1110a, a heat transfer fluid such as brine or gas flows. In one embodiment, the flow path 1110a is formed in the base 1110, and one or more heaters are disposed in the ceramic member 1111a of the electrostatic chuck 1111. In addition, the substrate support portion 11 may also include a heat transfer gas supply portion configured to supply a heat transfer gas to the gap between the back surface of the substrate W and the central region 111a.

[0058] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas introduction ports 13c. The processing gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s from the plurality of gas introduction ports 13c through the gas diffusion chamber 13b. In addition, the showerhead 13 includes at least one upper electrode. In addition, in addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGI) installed in one or more openings formed in the side wall 10a.

[0059] The gas supply unit 20 may also include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured such that each corresponding gas source 21 supplies at least one processing gas to the showerhead 13 via each corresponding flow controller 22. Each flow controller 22 may also include, for example, a mass flow controller or a pressure-controlled flow controller. Moreover, the gas supply unit 20 may also include one or more flow modulation devices for modulating or pulsing the flow rate of at least one processing gas.

[0060] The power supply 30 includes a radio frequency power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The radio frequency power supply 31 is configured to supply at least one radio frequency signal (radio frequency power) to at least one lower electrode and / or at least one upper electrode. Thereby, a plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the radio frequency power supply 31 can function as at least a part of the plasma generation unit 12. In addition, by supplying a bias radio frequency signal to at least one lower electrode, a bias potential can be generated on the substrate W, and the ion component in the formed plasma can be introduced into the substrate W.

[0061] In one embodiment, the radio frequency power supply 31 includes a first radio frequency generation unit 31a and a second radio frequency generation unit 31b. The first radio frequency generation unit 31a is configured to generate a source radio frequency signal (source radio frequency power) for plasma generation by being coupled to at least one lower electrode and / or at least one upper electrode via at least one impedance matching circuit. In one embodiment, the source radio frequency signal has a frequency in the range of 10 MHz to 150 MHz. In one embodiment, the first radio frequency generation unit 31a may also be configured to generate a plurality of source radio frequency signals having different frequencies. The generated one or more source radio frequency signals are supplied to at least one lower electrode and / or at least one upper electrode.

[0062] The second radio frequency generation unit 31b is configured to generate a bias radio frequency signal (bias radio frequency power) by being coupled to at least one lower electrode via at least one impedance matching circuit. The frequency of the bias radio frequency signal may be the same as or different from the frequency of the source radio frequency signal. In one embodiment, the bias radio frequency signal has a frequency lower than the frequency of the source radio frequency signal. In one embodiment, the bias radio frequency signal has a frequency in the range of 100 kHz to 100 MHz. In one embodiment, the second radio frequency generation unit 31b may also be configured to generate a plurality of different-frequency bias radio frequency signals. The generated one or more bias radio frequency signals are supplied to at least one lower electrode. In addition, in various embodiments, at least one of the source radio frequency signal and the bias radio frequency signal may be pulsed.

[0063] 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 generation unit 32a and a second DC generation unit 32b. In one embodiment, the first DC generation unit 32a is configured to be connected to at least one lower electrode and generate a first DC signal. The generated first DC signal is applied to at least one lower electrode. In one embodiment, the second DC generation 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.

[0064] In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to at least one lower electrode and / or at least one upper electrode. The voltage pulses may also have a pulse waveform that is rectangular, trapezoidal, triangular, or a combination thereof. In one embodiment, a waveform generation unit for generating a sequence of voltage pulses from a DC signal is connected between the first DC generation unit 32a and at least one lower electrode. Thus, the first DC generation unit 32a and the waveform generation unit constitute a voltage pulse generation unit. In the case where the second DC generation unit 32b and the waveform generation unit constitute a voltage pulse generation unit, the voltage pulse generation unit is connected to at least one upper electrode. The voltage pulses may have either 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 within one cycle. Further, the first and second DC generation units 32a, 32b may be provided in addition to the RF power supply 31, or the first DC generation unit 32a may be provided instead of the second RF generation unit 31b.

[0065] The exhaust system 40 can be connected to, for example, a gas discharge port 10e provided at the bottom of the plasma processing chamber 10. The exhaust system 40 may also include a pressure regulating valve and a vacuum pump. The pressure inside the plasma processing space 10s is regulated by the pressure regulating valve. The vacuum pump may also include a turbo molecular pump, a dry pump, or a combination thereof.

[0066] Figure 3 FIG. is a diagram for explaining an example of the structure of a substrate processing system. The substrate processing system PS includes substrate processing chambers (chambers) PM1 to PM6 (hereinafter collectively referred to as "substrate processing modules PM"), a transfer module TM, load lock modules LLM1 and LM2 (hereinafter collectively referred to as "load lock modules LLM"), a load machine module LM, and load ports LP1 to LP3 (hereinafter collectively referred to as "load ports LP"). The control unit CT controls each structure of the substrate processing system PS and performs a given process on the substrate W.

[0067] The substrate processing module PM performs processes such as etching, trimming, film formation, annealing, doping, lithography, cleaning, ashing, etc. on the substrate W inside it. A part of the substrate processing module PM may be Figure 2The capacitive coupling type plasma processing apparatus shown. That is, at least one of the substrate processing chambers PM1 to PM6 can be coupled to the capacitive coupling type plasma generation unit. A part of the substrate processing module PM can be an inductively coupled plasma processing apparatus. That is, at least one of the substrate processing chambers PM1 to PM6 can be coupled to the inductively coupled plasma generation unit. A part of the substrate processing module PM can be a measurement module. For example, an optical method can be used to measure the film thickness of the film formed on the substrate W or the size of the pattern formed on the substrate W, etc.

[0068] The transfer module TM has a transfer device for transferring the substrate W, and transfers the substrate W between the substrate processing modules PM or between the substrate processing module PM and the load lock module LLM. The substrate processing module PM and the load lock module LLM are adjacently arranged to the transfer module TM. The transfer module TM is spatially isolated or connected to the substrate processing module PM and the load lock module LLM through an openable and closable gate valve.

[0069] The load lock modules LLM1 and LLM2 are provided between the transfer module TM and the load machine module LM. The load lock module LLM can switch the pressure inside it to atmospheric pressure or vacuum. "Atmospheric pressure" can be the external pressure of each module included in the substrate processing system PS. In addition, "vacuum" can be a pressure lower than atmospheric pressure, for example, a medium vacuum of 0.1 Pa to 100 Pa. The load lock module LLM transfers the substrate W from the load machine module LM as atmospheric pressure to the transfer module TM as vacuum. In addition, the load lock module LLM transfers the substrate W from the transfer module TM as vacuum to the load machine module LM as atmospheric pressure.

[0070] The load machine module LM has a transfer device for transferring the substrate W, and transfers the substrate W between the load lock module LLM and the load port LP. Inside the load port LP, it is possible to place a FOUP (Front Opening Unified Pod: front-opening unified pod) that can accommodate, for example, 25 substrates W or an empty FOUP. The load machine module LM takes out the substrate W from the FOUP inside the load port LP and transfers it to the load lock module LLM. In addition, the load machine module LM takes out the substrate W from the load lock module LLM and transfers it to the FOUP inside the load port LP.

[0071] The control unit CT controls each structure of the substrate processing system PS and performs a given process on the substrate W. The control unit CT stores a recipe in which a process sequence, process conditions, transfer conditions, etc. are set, and according to this recipe, controls each structure of the substrate processing system PS so as to perform a given process on the substrate W. The control unit CT may also have a part or all of the functions of the control unit 2 as shown in Figure 1 shown.

[0072] <An example of a substrate processing method>

[0073] (First Embodiment)

[0074] Figure 4 is a flowchart showing an example of a substrate processing method (hereinafter also referred to as "this processing method") of the first embodiment. As Figure 4 shown, in one embodiment, this processing method includes: a step ST1 of providing a substrate, a step ST2 of selectively forming an additional mask on the mask of the substrate, and a step ST3 of etching an etching target film. In one embodiment, steps ST1, ST2, and ST3 are sequentially executed. In one embodiment, the processing in each step can be executed in a substrate processing system (see Figure 3 ). In the following examples, the control unit CT controls each part of the substrate processing system and executes this processing method.

[0075] (Step ST1: Providing a Substrate)

[0076] In one embodiment, as Figure 2 shown, in step ST1, a substrate W is provided in the chamber 10 of the plasma processing apparatus 1. The substrate W is provided in the central region 111a of the substrate support portion 11 and is held on the substrate support portion 11 by the electrostatic chuck 1111.

[0077] Figure 5 is a diagram for explaining a structural example of the substrate W provided in step ST1. The substrate W includes a bottom film UF, a stacked film SF on the bottom film UF, and a mask MK on the stacked film SF. The substrate W can be used for manufacturing semiconductor devices. The semiconductor devices include, for example, storage devices such as DRAM and 3D-NAND flash memories and logic devices.

[0078] In one embodiment, the bottom film UF is an organic film, a dielectric film, a metal film, a semiconductor film, etc. formed on a silicon wafer or a silicon wafer. The bottom film UF can be formed by laminating multiple films.

[0079] In one embodiment, the stacked film SF is a film to be etched in this processing method. In one embodiment, the stacked film SF contains two or more different silicon-containing films. In one embodiment, the stacked film SF has a stacked structure in which a silicon oxide film SF1 and a silicon nitride film SF2 are alternately laminated. The stacked film SF can have a thickness of 5 μm or more or 10 μm or more. The stacked film SF can have 20 layers or more, 50 layers or more, or 100 layers or more. The stacked film SF can contain two or more films selected from the group consisting of a single crystal silicon film, a polycrystalline silicon film, a silicon oxide film, and a silicon nitride film.

[0080] In one embodiment, the mask MK is a film used as a mask in the etching of the stacked film SF. The mask MK can be a hard mask. The mask MK includes at least one selected from the group consisting of a carbon-containing film, a silicon-containing film, and a metal-containing film. The mask MK can be an amorphous carbon film. The mask MK can be doped with elements such as phosphorus, boron, or nitrogen. The mask MK can be a film including at least one selected from the group consisting of WC (tungsten carbide), WSi (tungsten silicide), WSiN, and WSiC. The mask MK can be a single-layer mask composed of one film or a multi-layer mask composed of two or more films. The mask MK can have a thickness of 10 μm or less or 5 μm or less.

[0081] The mask MK has an upper surface U1 and sidewalls S1 that define at least one opening OP1 in the stacked film SF. The opening OP1 is a space on the stacked film SF and is surrounded by the sidewalls S1 of the mask MK. That is, the upper surface of the stacked film SF has an area covered by the mask MK and an area exposed at the bottom of the opening OP1.

[0082] The opening OP1 can have any shape when viewed from above the substrate W, that is, when looking at the substrate W in the Figure 5 direction from top to bottom. This shape can be, for example, a circle, an ellipse, a rectangle, a line, or a shape formed by a combination of one or more of them. The mask MK can have a plurality of sidewalls S1, and the plurality of sidewalls define a plurality of openings OP1. The plurality of openings OP1 each have a line shape and can also be arranged at a certain interval to form a pattern of lines and spaces. Additionally, the plurality of openings OP1 each have a hole shape and can also form an array pattern. The width of the opening OP1 can be 120 nm or less, 100 nm or less, 80 nm or less, or 50 nm or less.

[0083] Each film (bottom film UF, stacked film SF, mask MK) constituting the substrate W can be formed by chemical vapor deposition (CVD (Chemical Vapor Deposition)), atomic layer deposition (ALD (Atomic Layer Deposition)), molecular layer deposition (MLD (Molecular Layer Deposition)), spin coating, etc. In one embodiment, at least a part of the process of forming each film of the substrate W can be carried out as a part of the process ST1. In one embodiment, all or part of each film of the substrate W can be carried out in the same substrate processing system PS or plasma processing apparatus 1 (chamber 10) as the process ST1. Additionally, after all or part of each film of the substrate W is formed by an external device or chamber, the substrate W can be provided in the chamber of the plasma processing apparatus 1 performing the process ST1.

[0084] (Process ST2: Forming an additional mask)

[0085] Figure 6 This is a diagram showing a structural example of the substrate W on which the additional mask MK1 is formed in the process ST2. In one embodiment, in the process ST2, the additional mask MK1 is selectively formed on the mask MK of the substrate W. The additional mask MK1 is formed using plasma CVD method. In addition, "on the mask MK" includes not only the upper surface of the mask MK but also the upper surface of the film located on the upper surface of the mask MK. In addition, "selectively" includes selecting the exposed portion facing upward on the mask MK from the entire exposed portion of the mask MK.

[0086] In one embodiment, in the process ST2, the first processing gas is supplied from Figure 2 the showerhead 13 of the plasma processing apparatus 1 shown in the figure into the chamber 10. The temperature of the substrate support 11 or the substrate W can be controlled at the first temperature. The first temperature can be 200 °C or higher.

[0087] The first processing gas is a gas containing carbon and hydrogen. The first processing gas is a hydrocarbon gas (CxHy) (x and y are integers of 1 or more). The hydrocarbon gas can be C 2 H 2 gas, C 3 H 6 gas. The first processing gas may further contain an inert gas. The inert gas can be a noble gas such as Ar gas, He gas, and Kr gas or N 2 gas.

[0088] In one embodiment, plasma is generated from the first processing gas supplied into the chamber 10. In this case, a source radio frequency signal is supplied to the upper electrode and / or the lower electrode by the power supply 30, whereby a high-frequency electric field is generated on the substrate support 11, and plasma is generated from the first processing gas in the plasma processing space 10s. The source radio frequency signal has a frequency of 40 MHz or higher. The source radio frequency signal has a first power. The first power can be in the range of 100 W to 500 W.

[0089] When plasma is generated, a bias signal is supplied to the substrate support 11. The bias signal can be a bias radio frequency signal provided by the radio frequency power supply 31 or a bias direct current signal provided by the direct current power supply 32. The bias direct current signal can be a direct current pulse voltage. The absolute value of the direct current pulse voltage can be 200 V or less. The duty ratio of the direct current pulse voltage can be 20% or less and can be in the range of 5% to 20%, for example, about 10%. In addition, the frequency of the direct current pulse voltage can be in the range of 100 kHz to 1000 kHz. A bias potential is generated between the plasma and the substrate W, and ions or radicals in the plasma are attracted to the substrate W.

[0090] As Figure 6As shown, in one embodiment, carbon ions in the plasma are selectively deposited on the upper surface U1 of the mask MK to form an additional mask MK1. Deposition on the sidewall S1 of the mask MK is blocked by hydrogen radicals in the plasma. The additional mask MK1 is substantially formed only on the upper surface U1 of the mask MK. The additional mask MK1 has a thickness of 0.2 μm or more. The additional mask MK1 has a thickness of 2 μm or less. The total thickness of the mask MK and the additional mask MK1 can be 6 μm or more or 10 μm or more.

[0091] (Step ST3: Etching the stacked film SF)

[0092] Figure 7 FIG. is a structural example diagram of the substrate W on which the stacked film SF has been etched in step ST3. In step ST3, the stacked film SF is etched using plasma generated from an etching gas. Step ST3 can be performed in the chamber of the same plasma processing apparatus 1 as in step ST2, or can be performed in the chamber of another plasma processing apparatus 1. In the case of being performed by another plasma processing apparatus 1, within the substrate processing system PS, the substrate W can be transferred from the plasma processing apparatus 1 in which step ST2 has been performed to another plasma processing apparatus 1.

[0093] In one embodiment, in step ST3, the etching gas is supplied from Figure 2 the shown showerhead 13 into the plasma processing space 10s. The etching gas may contain hydrogen fluoride gas and at least one carbon-containing gas selected from the group consisting of CF gas (fluorocarbon gas) and CHF gas (hydrofluorocarbon gas). In one embodiment, the etching gas may contain hydrogen fluoride gas, CF gas, CHF gas, an oxygen-containing gas, and a fluorine-containing gas without carbon.

[0094] In one embodiment, plasma is generated from the etching gas supplied into the chamber 10. In this case, a source radio frequency signal is supplied to the upper electrode and / or the lower electrode by the power supply 30, whereby a high-frequency electric field is generated on the substrate support portion 11, and plasma is generated from the etching gas in the plasma processing space 10s. The source radio frequency signal may have a frequency of 13 MHz or more. The source radio frequency signal may have a first power. The first power may be 1 kW or more.

[0095] When plasma is generated, a bias signal is supplied to the substrate support portion 11. The bias signal may be a bias radio frequency signal supplied by the radio frequency power supply 31 or a bias direct current signal supplied by the direct current power supply 32. A bias potential is generated between the plasma and the substrate W. Active species such as ions and radicals in the plasma are attracted to the substrate W, and the stacked film SF is etched using this active species. The etching can be anisotropic etching using plasma of a fluorocarbon gas or a hydrofluorocarbon gas.

[0096] As Figure 7 shown, in one embodiment, the portion of the stacked film SF not covered by the mask MK and the additional mask MK1 (the portion exposed in the opening OP1) is etched, and an opening OP2 is formed in the stacked film SF. In the stacked film SF, an opening OP2 with an aspect ratio (A / R) of 100 or more can be formed. The opening OP2 can have, for example, a critical dimension (CD) of 80 nm or less and a depth of 10 μm or more.

[0097] Then, the mask MK on the substrate W is removed by ashing. The ashing of the mask MK can be performed, for example, using a plasma of an oxygen-based gas.

[0098] According to the present exemplary embodiment, the substrate processing method includes a step ST1 of providing a substrate, a step ST2 of selectively forming an additional mask MK1 containing carbon on the mask MK using a plasma generated from a processing gas containing carbon and hydrogen, and a step ST3 of etching an etching target film using a plasma generated from an etching gas. Generally, when the mask becomes thick (the opening becomes deep), the dimensional accuracy of the opening formed in the mask decreases. According to the present exemplary embodiment, since the additional mask MK1 is subsequently attached to the mask MK, the thickness of the mask MK at the initial formation can be suppressed, and thus the dimensional accuracy of the opening of the mask MK can be improved. As a result, the etching shape when etching the etching target film using the mask can be improved.

[0099] In the present exemplary embodiment, the opening OP1 of the mask MK is formed by plasma etching. In this case, as Figure 8 shown, the present processing method may include a step ST0-1 of forming a mask MK on the stacked film SF and a step ST0-2 of patterning the mask MK to form an opening OP1.

[0100] In one embodiment, as Figure 9 shown, in step ST0-1, the mask MK is formed on the stacked film SF. The mask MK can be formed using various methods such as CVD, ALD, MLD, spin coating, etc.

[0101] In step ST0-2, as Figure 10 shown, a first film F1 having an opening OP3 is formed on the mask MK. The first film F1 can be a silicon-containing film. The opening OP3 of the first film F1 is formed by photolithography. In this case, first, a flat first film F1 is formed on the mask MK, and an antireflection film F2 and a resist film F3 are formed on the first film F1. Then, a resist pattern having an opening pattern is formed by exposure and development, and thereafter, the first film F1 is etched using the resist pattern. Thus, an opening OP3 is formed on the first film F1.

[0102] Then, as shown in Figure 11 , the first film F1 including the opening OP3 functions as a mask, and the mask MK is etched to form the opening OP1. In addition, the process ST0-1 and / or the process ST0-2 can be performed in the same substrate processing system PS as the process ST2 or the process ST3.

[0103] In the case where the opening OP1 of the mask MK is formed by plasma etching, if the mask MK is thick, the vertical component of the ions in the plasma may be lost during plasma etching. In this case, the lower part of the opening of the mask MK becomes narrow, the side wall of the opening of the mask MK is etched laterally, and the shape of the opening of the mask MK may be defective. According to the present exemplary embodiment, since the additional mask MK1 is formed in the process ST2, when the opening OP1 of the mask MK is formed, the thickness of the mask MK can be suppressed. As a result, the defective shape of the opening of the mask MK can be avoided, and as a result, the etching shape of the film to be etched can be improved.

[0104] In the present exemplary embodiment, the substrate W provided in the process ST1 may have the first film F1 on the mask MK. The first film F1 may be a film remaining after the etching for forming the opening OP1 of the mask MK. In this case, as shown in Figure 12 , the present processing method may include a process ST4 of removing the first film F1 between the process ST1 and the process ST2.

[0105] In the process ST4, the first film F1 is removed by a processing gas or a processing liquid. The first film F1 can be removed, for example, using a chemical solution mixed with HF and water. Thereby, the upper surface U1 of the mask MK is flattened. In the next process ST2, the additional mask MK1 is formed on the flattened mask MK.

[0106] In the present exemplary embodiment, a cycle including the processes ST2 and ST3 can be performed multiple times in sequence. Figure 13 is a flowchart showing an example of the present processing method. As shown in Figure 14 , in the process ST3, the portion of the stacked film SF not covered by the mask MK and the additional mask MK1 (the portion exposed in the opening OP1) is etched, and a recess R1 is formed on a part of the film of the stacked film SF. Then, when the cycle including the processes ST2 and ST3 has not been performed a preset specified number of times, the processes ST2 and ST3 are performed again. As shown in Figure 15 , the additional mask MK1 is formed on the mask MK, and then the bottom of the recess R1 of the stacked film SF is etched deeper. Then, when the cycle including the processes ST2 and ST3 has been performed the specified number of times, the present processing method ends. At this time, as shown inFigure 7 The opening OP2 shown. The specified number of times of the cycle can be 2 or more, 5 or more, 10 or more. In addition, when the mask MK is less than the specified thickness in the process ST3, the cycles of the process ST2 and the process ST3 can be performed again.

[0107] In the case of performing plasma etching on an etching target film using a mask, if the mask is gradually shaved off and the remaining film thickness of the mask becomes smaller, the sidewalls are etched laterally in the opening of the etching target film, and so-called bowing may occur. According to the present exemplary embodiment, since multiple cycles each including the process ST2 and the process ST3 are performed, an additional mask MK1 can be added in the middle of the etching, and the film thickness of the entire mask can be maintained. As a result, bowing can be suppressed and the etching shape of the etching target film can be improved.

[0108] (Second Embodiment)

[0109] In the present processing method in the present exemplary embodiment, after the process ST1, the process ST3 is performed, and then, one or more cycles each including the process S2 and the process ST3 are performed in sequence. Figure 16 It is a flowchart showing an example of the present processing method.

[0110] In one embodiment, as Figure 5 shown, in the process ST1, a substrate W including a base film UF, a stacked film SF on the base film UF, and a mask MK on the stacked film SF is provided. The substrate W is provided in the chamber 10 of the plasma processing apparatus 1 that performs the process ST3.

[0111] Next, the process ST3 is performed, and the stacked film SF is etched using the plasma generated from the etching gas. As Figure 17 shown, in one embodiment, the portion of the stacked film SF that is not covered by the mask MK (the portion exposed in the opening OP1) is etched, and a recess R1 is formed in the stacked film SF.

[0112] Next, the process ST2 is performed. As Figure 18 shown, an additional mask MK1 is selectively formed on the mask MK of the substrate W.

[0113] Next, the process ST3 is performed. As Figure 19 shown, the stacked film SF is etched using the plasma generated from the etching gas. The portion of the stacked film SF that is not covered by the mask MK and the additional mask MK1 (the portion exposed in the opening OP1) is etched, and a deeper recess R2 is formed on the stacked film SF.

[0114] Then, when the loop including process ST2 and process ST3 has not been performed a preset specified number of times, processes ST2 and ST3 are performed again. When the loop including process ST2 and process ST3 has been performed the specified number of times, this processing method ends. At this time, an opening OP2 as shown in Figure 7 can be formed on the laminated film SF. The loop including process ST2 and process ST3 can be performed more than twice. In addition, many conditions of each process in this embodiment can be the same as those in the above first embodiment.

[0115] According to this exemplary embodiment, after processes ST1 and ST3, the loop including processes ST2 and ST3 is performed one or more times, so that an additional mask MK1 can be added in the middle of etching, and the film thickness of the entire mask can be maintained. As a result, the etching shape of the film to be etched can be improved.

[0116] In the above first and second embodiments, when processes ST2 and ST3 and their repetitions are performed, in the above substrate processing system PS, any one of the transfer module TM and the substrate processing chambers PM1 to PM6 can be used to continuously process the substrate while maintaining a vacuum environment.

[0117] The film to be etched in the above first and second embodiments is not limited to the laminated film SF. The film to be etched can be a single-layer film or a multi-layer film selected from at least one of the group consisting of a single-crystalline silicon film, a polycrystalline silicon film, a silicon oxide film, and a silicon nitride film.

[0118] In the above first and second embodiments, this processing method is not limited to an inductively coupled plasma processing apparatus, and can also be performed by other types of plasma processing apparatuses, such as a plasma processing apparatus that generates capacitively coupled plasma, a plasma processing apparatus that generates ECR plasma, a plasma processing apparatus that generates helicon wave-excited plasma, or a plasma processing apparatus that generates surface wave plasma.

[0119] This disclosure may include, for example, the following configurations.

[0120] (Appended Note 1)

[0121] A substrate processing method, comprising:

[0122] (a) A process of providing a substrate including a film to be etched and a mask on the film to be etched, the mask including sidewalls defining at least one opening;

[0123] (b) A process of selectively forming an additional mask containing carbon on the mask using a plasma generated from a processing gas containing carbon and hydrogen; and

[0124] (c) A step of etching the etched target film using a plasma generated from an etching gas.

[0125] (Supplementary Note 2)

[0126] According to the substrate processing method described in Supplementary Note 1, the step (b) is performed after the step (a).

[0127] (Supplementary Note 3)

[0128] According to the substrate processing method described in Supplementary Note 2, the substrate in the step (a) includes a first film on the mask, and the substrate processing method further includes (d) a step of removing the first film between the step (a) and the step (b).

[0129] (Supplementary Note 4)

[0130] According to the substrate processing method described in Supplementary Note 2 or 3, multiple cycles are performed, and each cycle sequentially includes the step (b) and the step (c).

[0131] (Supplementary Note 5)

[0132] According to the substrate processing method described in Supplementary Note 1, the step (c) is performed after the step (a), and then one or more cycles sequentially including the step (b) and the step (c) are performed.

[0133] (Supplementary Note 6)

[0134] According to the substrate processing method described in any one of Supplementary Notes 1 to 5, the mask has a thickness of 10 μm or less.

[0135] (Supplementary Note 7)

[0136] According to the substrate processing method described in any one of Supplementary Notes 1 to 6, the mask includes at least one selected from the group consisting of a carbon-containing film, a silicon-containing film, and a metal-containing film.

[0137] (Supplementary Note 8)

[0138] According to the substrate processing method described in any one of Supplementary Notes 1 to 7, the additional mask has a thickness of 0.2 μm or more.

[0139] (Supplementary Note 9)

[0140] According to the substrate processing method described in any one of Supplementary Notes 1 to 8, the additional mask has a thickness of 2 μm or less.

[0141] (Supplementary Note 10)

[0142] According to the substrate processing method described in any one of Supplementary Notes 1 to 9, the additional mask includes an amorphous carbon film.

[0143] (Supplementary Note 11)

[0144] The substrate processing method according to any one of Supplementary Notes 1 to 10, wherein the film to be etched comprises a stacked film, and the stacked film comprises two or more different silicon-containing films.

[0145] (Supplementary Note 12)

[0146] The substrate processing method according to any one of Supplementary Notes 1 to 11, wherein the film to be etched comprises a stacked film in which a silicon oxide film and a silicon nitride film are alternately stacked.

[0147] (Supplementary Note 13)

[0148] The substrate processing method according to any one of Supplementary Notes 1 to 12, wherein the opening of the mask is formed by plasma etching.

[0149] (Supplementary Note 14)

[0150] A substrate processing system, comprising a substrate support portion, a plasma generation portion, and a control portion disposed in a chamber.

[0151] The control portion executes:

[0152] (a) Control to supply a substrate including a film to be etched and a mask on the film to be etched to the substrate support portion, the mask including side walls defining at least one opening;

[0153] (b) Control to generate a plasma from a processing gas containing carbon and hydrogen by the plasma generation portion, and selectively form an additional mask containing carbon on the mask; and

[0154] (c) Control to generate a plasma from an etching gas by the plasma generation portion, and etch the film to be etched.

[0155] (Supplementary Note 15)

[0156] The substrate processing system according to Supplementary Note 14, wherein the substrate processing system comprises a plurality of chambers and a transfer module capable of transferring a substrate to the plurality of chambers in a vacuum environment.

[0157] The control portion uses any one of the plurality of chambers to execute the controls of (a), (b), and (c) while maintaining a vacuum environment.

[0158] In the above exemplary embodiments, the substrate processing method and the substrate processing system can be variously modified without departing from the scope and gist of the present disclosure. For example, within the normal creative ability of those skilled in the art, some constituent elements in one embodiment can be added to other embodiments. Additionally, some constituent elements in one embodiment can be replaced with corresponding constituent elements in other embodiments.

Claims

1. A substrate processing method, comprising: (a) providing a substrate including a film to be etched and a mask on the film to be etched, wherein the mask includes a side wall defining at least one opening; (b) a step of selectively forming an additional mask containing carbon on the mask using plasma generated from a process gas containing carbon and hydrogen; and (c) A step of etching the etching target film using plasma generated from the etching gas.

2. The substrate processing method according to claim 1, wherein: The step (b) is performed after the step (a).

3. The substrate processing method according to claim 2, wherein: The substrate in the step (a) includes a first film on the mask, The substrate processing method further includes (d) a step of removing the first film between the step (a) and the step (b).

4. The substrate processing method according to claim 2, wherein: A plurality of cycles are performed, wherein the cycles sequentially include the step (b) and the step (c).

5. The substrate processing method according to claim 1, wherein: After the step (a), the step (c) is performed, and then a cycle including the steps (b) and (c) in sequence is performed one or more times.

6. The substrate processing method according to claim 1, wherein: The mask has a thickness of 10 μm or less.

7. The substrate processing method according to claim 1, wherein: The mask includes at least one selected from the group consisting of a carbon-containing film, a silicon-containing film, and a metal-containing film.

8. The substrate processing method according to claim 1, wherein: The additional mask has a thickness of 0.2 μm or more.

9. The substrate processing method according to claim 1, wherein: The additional mask has a thickness of 2 μm or less.

10. The substrate processing method according to claim 1, wherein: The additional mask includes an amorphous carbon film.

11. The substrate processing method according to claim 1, wherein: The etching target film includes a stacked film including two or more different silicon-containing films.

12. The substrate processing method according to claim 1, wherein: The etching target film includes a stacked film in which silicon oxide films and silicon nitride films are alternately stacked.

13. The substrate processing method according to claim 1, wherein: The opening of the mask is formed by plasma etching.

14. A substrate processing system comprising a substrate support unit, a plasma generating unit and a control unit arranged in a chamber, The control unit performs: (a) providing a substrate including an etching target film and a mask on the etching target film to a control of a substrate support portion, wherein the mask includes a side wall defining at least one opening; (b) generating plasma from a process gas containing carbon and hydrogen by a plasma generating unit to selectively form an additional mask containing carbon on the mask; and (c) A plasma generating unit generates plasma from an etching gas to control etching of the etching target film.

15. The substrate processing system according to claim 14, wherein: The substrate processing system comprises a plurality of chambers and a conveying module capable of conveying substrates to the plurality of chambers in a vacuum environment. The control unit performs the control of (a), (b), and (c) while maintaining a vacuum environment using any one of the plurality of chambers.

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