Substrate processing method, substrate processing apparatus, and substrate processing system

Abstract

To provide a technique for modifying a tin-containing film on a substrate.SOLUTION: In one exemplary embodiment, a substrate processing method is provided. A substrate processing method includes a step of preparing, in a chamber, a substrate having an etching target film and a tin-containing film defining at least one opening on the etching target film, and a step of supplying a processing gas containing a halogen-containing gas or an oxygen-containing gas into the chamber to form a modified film on a surface of the tin-containing film.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] An exemplary embodiment of the present disclosure relates to a method for processing a substrate. [Background technology]

[0002] Patent Document 1 relates to a pattern formation method for semiconductor devices and discloses a technique of using a thin tin oxide film as an etching mask. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-6742 Summary of the Invention [Problem to be solved by the invention]

[0004] The present disclosure provides techniques for modifying tin-containing films on substrates. [Means for solving the problem]

[0005] In one embodiment of the present disclosure, a substrate processing method is provided, which includes the steps of: providing a substrate having a film to be etched and a tin-containing film defining at least one opening on the film to be etched in a chamber; and supplying a processing gas containing a halogen-containing gas or an oxygen-containing gas into the chamber to form a modified film on a surface of the tin-containing film. [Effects of the Invention]

[0006] According to exemplary embodiments of the present disclosure, techniques can be provided for modifying tin-containing films on substrates. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a diagram schematically illustrating a substrate processing apparatus 1. FIG. [Figure 2]FIG. 1 is a diagram schematically illustrating a substrate processing system PS. [Figure 3] 1 is a flowchart showing the present processing method. [Figure 4A] FIG. 10 is a diagram showing an example of a cross-sectional structure of a substrate W prepared in step ST1. [Figure 4B] 10 is a diagram showing an example of a cross-sectional structure of the substrate W in step ST2. FIG. [Figure 4C] FIG. 10 is a diagram showing an example of the cross-sectional structure of the substrate W in step ST3. [Figure 5] 10 is a diagram showing another example of the cross-sectional structure of the substrate W. FIG. [Figure 6] FIG. 7 is a diagram showing another example of the third film 102c of FIG. 5. [Figure 7] 10 is a flowchart showing a modified example of the present processing method. [Figure 8] FIG. 1 is a diagram showing an example of a timing chart for ALD using plasma. [Figure 9] FIG. 1 is a diagram showing an example of a timing chart for ALD without using plasma. [Figure 10] FIG. 10 is a diagram showing an example of a selectively formed deposition film. [Figure 11] FIG. 1 is a diagram showing an example of a deposited film formed by sputtering. [Figure 12] FIG. 10 is a diagram showing the results of a modification process according to an example. DETAILED DESCRIPTION OF THE INVENTION

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

[0009] In one exemplary embodiment, a substrate processing method is provided, which includes providing a substrate having a film to be etched and a tin-containing film defining at least one opening on the film to be etched in a chamber, and supplying a process gas containing a halogen-containing gas or an oxygen-containing gas into the chamber to form a modified film on a surface of the tin-containing film.

[0010] In one exemplary embodiment, forming the modified film may include generating a plasma from a process gas and forming the modified film on the tin-containing film with the generated plasma.

[0011] In one exemplary embodiment, forming the modified film may include reacting a treatment gas with a surface of the tin-containing film to form the modified film.

[0012] In one exemplary embodiment, the modified film may include tin-halogen bonds.

[0013] In one exemplary embodiment, after the step of forming the modified film, the method may further include the step of forming a deposition film on the tin-containing film.

[0014] In one exemplary embodiment, the deposited film may be formed by plasma CVD.

[0015] In one exemplary embodiment, the deposited film may be selectively formed on top of the tin-containing film.

[0016] In one exemplary embodiment, the deposited film may be formed by sputtering a top electrode disposed above the substrate.

[0017] In one exemplary embodiment, sputtering may include generating a plasma between the substrate and an upper electrode and providing the upper electrode with a negative potential.

[0018] In one exemplary embodiment, the steps of forming the deposition film and forming the modified film may be performed in the same chamber.

[0019] In one exemplary embodiment, the method may further include a step of etching the film to be etched after the step of forming the modified film.

[0020] In one exemplary embodiment, the step of etching the film to be etched and the step of forming the deposition film may be performed in the same chamber.

[0021] In one exemplary embodiment, the tin-containing film may be a photoresist.

[0022] Hereinafter, each embodiment of the present disclosure will be described in detail with reference to the drawings. In each drawing, the same or similar elements are designated by the same reference numerals, and redundant explanations will be omitted. Unless otherwise specified, the positional relationships, such as up, down, left, and right, will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not represent actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

[0023] <Configuration of substrate processing apparatus 1> 1 is a diagram schematically illustrating a substrate processing apparatus 1 according to an exemplary embodiment. A substrate processing method according to an exemplary embodiment (hereinafter referred to as “this processing method”) may be performed using the substrate processing apparatus 1.

[0024] The substrate processing apparatus 1 is a capacitively coupled plasma processing apparatus. The substrate processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, an exhaust system 40, and a control unit 50. The substrate processing apparatus 1 also includes a substrate support 11 and a gas inlet unit. The gas inlet unit is configured to introduce at least one process gas into the plasma processing chamber 10. The gas inlet unit includes a showerhead 13. The substrate support 11 is disposed within the plasma processing chamber 10. The showerhead 13 is disposed above the substrate support 11. In one exemplary embodiment, the showerhead 13 forms at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the showerhead 13, a sidewall 10a of the plasma processing chamber 10, and the substrate support 11. The plasma processing chamber 10 has at least one gas inlet for supplying at least one process gas to the plasma processing space 10s and at least one gas outlet for exhausting gas from the plasma processing space 10s. The sidewall 10a is grounded. The showerhead 13 and the substrate support 11 are electrically isolated from the plasma processing chamber 10 housing.

[0025] The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region (substrate support surface) 111a for supporting a substrate (wafer) W and an annular region (ring support surface) 111b for supporting the ring assembly 112. 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. In one exemplary embodiment, the main body 111 includes a base and an electrostatic chuck. The base includes a conductive member. The conductive member of the base functions as a lower electrode. The electrostatic chuck is disposed on the base. The upper surface of the electrostatic chuck has the substrate support surface 111a. The ring assembly 112 includes one or more annular members. At least one of the one or more annular members is an edge ring. Although not shown, the substrate support 11 may also include a temperature control module configured to adjust at least one of the electrostatic chuck, the ring assembly 112, and the substrate to a target temperature. The temperature control module may include a heater, a heat transfer medium, a flow path, or a combination thereof. A heat transfer fluid such as brine or gas flows through the flow path. The substrate support 11 may also include a heat transfer gas supply unit configured to supply a heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

[0026] The showerhead 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The showerhead 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The showerhead 13 also includes a conductive member. The conductive member of the showerhead 13 functions as an upper electrode. In addition to the showerhead 13, the gas introduction unit may also include one or more side gas injectors (SGIs) attached to one or more openings formed in the sidewall 10a.

[0027] The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one exemplary embodiment, the gas supply unit 20 is configured to supply at least one process gas from a corresponding gas source 21 to the showerhead 13 via a corresponding flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include one or more flow modulation devices to modulate or pulse the flow rate of the at least one process gas.

[0028] The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to the conductive members of the substrate support 11 and / or the conductive members of the showerhead 13. This causes plasma to be formed from at least one process gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least a part of a plasma generating unit configured to generate plasma from one or more process gases in the plasma processing chamber 10. Furthermore, supplying a bias RF signal to the conductive members of the substrate support 11 generates a bias potential on the substrate W, thereby attracting ion components in the formed plasma to the substrate W.

[0029] In one exemplary 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 conductive members of the substrate support 11 and / or the conductive members of the showerhead 13 via at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for plasma generation. In one exemplary embodiment, the source RF signal has a frequency in the range of 13 MHz to 150 MHz. In one exemplary 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 conductive members of the substrate support 11 and / or the conductive members of the showerhead 13. The second RF generating unit 31b is coupled to the conductive members of the substrate support 11 via at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). In one exemplary embodiment, the bias RF signal has a frequency lower than that of the source RF signal. In one exemplary embodiment, the bias RF signal has a frequency in the range of 400 kHz to 13.56 MHz. In one exemplary embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are supplied to the conductive members of the substrate support 11. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

[0030] The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one exemplary embodiment, the first DC generator 32a is connected to a conductive member of the substrate support 11 and configured to generate a first DC signal. The generated first bias DC signal is applied to the conductive member of the substrate support 11. In one exemplary embodiment, the first DC signal may be applied to another electrode, such as an electrode in an electrostatic chuck. In one exemplary embodiment, the second DC generator 32b is connected to a conductive member of the showerhead 13 and configured to generate a second DC signal. The generated second DC signal is applied to the conductive member of the showerhead 13. In various embodiments, at least one of the first and second DC signals may be pulsed. The first and second DC generating units 32a and 32b may be provided in addition to the RF power supply 31, and the first DC generating unit 32a may be provided instead of the second RF generating unit 31b.

[0031] The exhaust system 40 may be connected to a gas outlet 10e provided at the bottom of the plasma processing chamber 10, for example. 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.

[0032] The control unit 50 processes computer-executable instructions that cause the substrate processing apparatus 1 to perform various processes described in this disclosure. The control unit 50 may be configured to control each element of the substrate processing apparatus 1 to perform the various processes described herein. In one exemplary embodiment, part or all of the control unit 50 may be provided as part of a device configuration external to the substrate processing apparatus 1. The control unit 50 may include, for example, a computer 50a. The computer 50a may include, for example, a processing unit (CPU: Central Processing Unit) 50a1, a memory unit 50a2, and a communication interface 50a3. The processing unit 50a1 may be configured to perform various control operations based on programs stored in the memory unit 50a2. The memory unit 50a2 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 50a3 may communicate with other components of the substrate processing apparatus 1 via a communication line such as a local area network (LAN).

[0033] <Configuration of the Substrate Processing System PS> 2 is a schematic diagram of a substrate processing system PS according to one exemplary embodiment, which may be used to perform the present processing method.

[0034] The substrate processing system PS has substrate processing chambers PM1 to PM6 (hereinafter also collectively referred to as "substrate processing modules PM"), a transfer module TM, load lock modules LLM1 and LLM2 (hereinafter also collectively referred to as "load lock modules LLM"), a loader module LM, and load ports LP1 to LP3 (hereinafter also collectively referred to as "load ports LP"). A control unit CT controls each component of the substrate processing system PS to perform a predetermined process on a substrate W.

[0035] The substrate processing module PM performs processes such as etching, trimming, film formation, annealing, doping, lithography, cleaning, and ashing on the substrate W. A part of the substrate processing module PM may be a measurement module, which may measure the thickness of a film formed on the substrate W or the dimensions of a pattern formed on the substrate W. The substrate processing apparatus 1 shown in FIG. 1 is an example of the substrate processing module PM.

[0036] The transfer module TM has a transfer device for transferring a 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 arranged adjacent to the transfer module TM. The transfer module TM, the substrate processing module PM, and the load lock module LLM are spatially isolated from or connected to each other by openable and closable gate valves.

[0037] The load lock modules LLM1 and LLM2 are provided between the transfer module TM and the loader module LM. The load lock module LLM can switch its internal pressure between atmospheric pressure and vacuum. The load lock module LLM transfers a substrate W from the loader module LM, which is at atmospheric pressure, to the transfer module TM, which is at vacuum, and also transfers the substrate W from the transfer module TM, which is at vacuum, to the loader module LM, which is at atmospheric pressure.

[0038] The loader module LM has a transport device for transporting substrates W, and transports substrates W between the load lock module LLM and the load board LP. A FOUP (Front Opening Unified Pod) that can store, for example, 25 substrates W, or an empty FOUP can be placed inside the load port LP. The loader module LM removes substrates W from the FOUP in the load port LP and transports them to the load lock module LLM. The loader module LM also removes substrates W from the load lock module LLM and transports them to the FOUP in the load board LP.

[0039] The controller CT controls each component of the substrate processing system PS to perform a predetermined process on the substrate W. The controller CT stores a recipe in which the process procedure, process conditions, transport conditions, etc. are set, and controls each component of the substrate processing system PS to perform the predetermined process on the substrate W in accordance with the recipe. The controller CT may also have some or all of the functions of the controller 50 of the substrate processing apparatus 1 shown in FIG.

[0040] <An example of this processing method> 3 is a flowchart showing the present processing method. As shown in FIG. 3, the present processing method includes a step of preparing a substrate W (step ST1), a step of forming a modified film (step ST2), and a step of performing etching (step ST3).

[0041] 3 will be described below with reference to Figures 4A to 4C, 5, and 6. The following describes an example in which the control unit 50 controls each unit of the substrate processing apparatus 1 (see Figure 1) to execute the present processing method.

[0042] (Preparation of substrate W: Step ST1) 4A is a diagram showing an example of the cross-sectional structure of the substrate W prepared in step ST1. In ST1, the substrate W is prepared in the plasma processing space 10s of the plasma processing chamber 10. In the plasma processing space 10s, the substrate W is placed on the substrate support surface 111a of the substrate support 11 and held by an electrostatic chuck. At least a part of the process for forming each component of the substrate W may be performed in the plasma processing space 10s. Alternatively, the substrate W may be placed in the plasma processing space 10s after all or a part of each component of the substrate W has been formed in an apparatus or chamber external to the substrate processing apparatus 1.

[0043] The substrate W prepared in step ST1 is formed by laminating, for example, an undercoat film 101, a film to be etched 102, and a tin-containing film 103 in this order.

[0044] The base film 101 may be, for example, a silicon wafer, an organic film formed on a silicon wafer, a dielectric film, a metal film, a semiconductor film, etc. The base film 101 may be configured by laminating a plurality of films.

[0045] The film to be etched 102 may be, for example, an organic film, a dielectric film, a semiconductor film, or a metal film. The film to be etched 102 may be composed of a single film or may be composed of a plurality of films stacked together.

[0046] The tin-containing film 103 includes, for example, tin oxide and / or tin hydroxide. The tin-containing film 103 may include an organic material, for example, a photoresist.

[0047] Each of the films constituting the substrate W (the base film 101, the film to be etched 102, and the tin-containing film 103) may be formed by a CVD method, an ALD method, a spin coating method, etc. Each of the above films may be a flat film or may have an uneven surface.

[0048] The tin-containing film 103 has an upper surface TS and a side surface SS extending in a direction different from the upper surface TS (for example, a vertical direction). The tin-containing film 103 has an opening pattern. The opening pattern defines at least one opening OP on the etching target film 102. The opening OP is a space above the etching target film 102 and is surrounded by the side surface SS of the tin-containing film 103. The etching target film 102 has a region covered by the tin-containing film 103 and a region exposed at the bottom of the opening OP.

[0049] The opening pattern of the tin-containing film 103 may have any shape in a plan view of the substrate W (when the substrate W is viewed from top to bottom in FIG. 4A ). The opening pattern may be, for example, a line-and-space (L / S) pattern in which a plurality of linear openings OP are arranged at regular intervals in a plan view, or an array pattern in which a plurality of hole-shaped openings OP, such as circular, elliptical, or rectangular, are arranged in a plan view.

[0050] The opening pattern of the tin-containing film 103 may be formed by, for example, lithography. Specifically, for example, first, a tin-containing photoresist film is formed on the film 102 to be etched. Then, using an exposure mask, the photoresist film is selectively irradiated with light (for example, an EUV excimer laser, etc.) to expose the opening pattern to the photoresist film. Then, the exposed photoresist film is developed. In this way, the tin-containing film 103 having the opening pattern may be formed. When the opening pattern is a line and space (L / S) pattern, the half pitch may be, for example, 18 nm. Alternatively, for example, the opening pattern of the tin-containing film 103 may be formed by etching.

[0051] The substrate W prepared in step ST1 can take various forms. FIG. 5 is a diagram showing another example of the cross-sectional structure of the substrate W. As shown in FIG. 5, the film 102 to be etched may be configured by stacking multiple films and may include a first film 102a, a second film 102b, and a third film 102c. The first film 102a, the second film 102b, and the third film 102c may have different etching characteristics. The tin-containing film 103, the first film 102a, and the second film 102b may form a three-layer multilayer mask with respect to the third film 102c. In this case, the opening pattern of the tin-containing film 103 is sequentially transferred to the first film 102a, the second film 102b, and the third film 102c by etching.

[0052] The first film 102a is, for example, a spin-on-glass (SOG) film, a SiON film, a Si-containing anti-reflective coating (SiARC), etc. The first film 102a may be configured by laminating a plurality of films, for example, by laminating an anti-reflective coating (BARC) on a SiON film.

[0053] The second film 102b is, for example, a carbon-containing film such as a spin-on carbon (SOC) film or an amorphous carbon (Amorphous Carbon Layer: ACL) film.

[0054] The third film 102c may be a silicon-containing dielectric film such as SiC, SiON, SiN, and / or SiO. The third film 102c may be formed by stacking multiple films, for example, by stacking multiple silicon oxide films or silicon nitride films.

[0055] Fig. 6 is a diagram showing another example of the third film 102c of Fig. 5. As shown in Fig. 6, the third film 102c may be formed by arranging a plurality of films (SiN film 102c1, SiO film 102c2, and SiC film 102c3) in a predetermined order in a direction perpendicular to the stacking direction (the left-right direction in Fig. 6). Any of the SiN film 102c1, SiO film 102c2, and SiC film 102c3 may be selectively etched.

[0056] (Formation of modified film: Step ST2) 4B is a diagram showing an example of a cross-sectional structure of the substrate W in step ST2. As shown in FIG. 4B, in step ST2, a modified film 103a is formed on the tin-containing film 103 (hereinafter, this process is also referred to as a "modification process"). Specifically, first, a process gas containing a halogen-containing gas or an oxygen-containing gas is supplied from the gas supply unit 20 into the plasma processing space 10s.

[0057] The halogen-containing gas may include, for example, one or more gases consisting of molecules containing F, Cl, Br, or I, such as CHF3, CF4, NF3, SF6, IF7, HF, HBr, Cl2, BCl3, Br2, SiF4, and / or SiCl4. A gas consisting of molecules that do not contain H (hydrogen) (in the above example, CF4, NF3, SF6, IF7, Cl2, BCl3, Br2, SiF4, and / or SiCl4, etc.) may also be used as the halogen-containing gas. The oxygen-containing gas may include, for example, one or more gases consisting of molecules containing O, such as CO, O2, CO2, O3, NO, NO2, SO2, and / or COS. The process gas may include a noble gas such as Ar and an inert gas such as N2.

[0058] Next, an RF signal is supplied to the plasma processing space 10s from the RF power supply 31, and plasma of the processing gas is generated in the plasma processing space 10s. Ions and radicals in the generated plasma chemically bond with tin on the surface (top surface TS and side surface SS) and near the surface (hereinafter collectively referred to as "surface, etc.") of the tin-containing film 103, thereby forming a modified film 103a on the surface, etc. of the tin-containing film 103.

[0059] The modification process does not necessarily require the use of plasma. That is, a process gas containing a halogen-containing gas or an oxygen-containing gas may be supplied from the gas supply unit 20 into the plasma processing space 10s, and the process gas may be directly reacted with the surface of the tin-containing film 103 to form the modified film 103a. The process gas may contain highly reactive gases, such as HF, IF, and O gas, even without being converted into plasma (even in the raw gas state). Note that the reactivity of the process gas may be enhanced by applying thermal energy, electromagnetic energy, light energy, or other energy to the process gas.

[0060] When the processing gas contains a halogen-containing gas, the modified film 103a contains tin halide (tin-halogen bond). When the processing gas contains an oxygen-containing gas, the modified film 103a has accelerated tin oxidation compared to other parts of the tin-containing film 103, and contains more tin oxide (or tin-oxygen bond). The bond energy of tin-halogen bonds and tin-oxygen bonds is higher than the bond energy of tin-tin bonds. Therefore, tin halides and tin oxides with many tin-halogen bonds and tin-oxygen bonds have higher melting points and boiling points and are more thermally stable than tin halides and tin oxides with fewer tin-halogen bonds and tin-oxygen bonds. Therefore, the modified film 103a is more thermally and chemically stable than other parts of the tin-containing film 103, and its chemical resistance, such as plasma resistance, is improved. For example, the tin-containing film 103 having the modified film 103a formed thereon may have improved etching or corrosion resistance (the etching rate may be slower) to the etching gas that etches the film to be etched 102 compared to the tin-containing film 103 not having the modified film 103a formed thereon. The modified film 103a has a thickness of, for example, 1 to 2 nm. The modified film 103a may be formed on all or part of the surface of the tin-containing film 103.

[0061] Furthermore, the modification treatment can harden the modified film 103a and / or reduce the impurity content compared to other portions of the tin-containing film 103. This can improve the chemical resistance of the tin-containing film 103. Furthermore, the modification treatment can make the dimensions / shape of the opening pattern of the tin-containing film 103 more uniform than before the modification treatment. For example, when the opening pattern is a line and space (L / S) pattern, the line edge roughness (LER) and line width roughness (LWR) can be improved.

[0062] (Etching execution: Step ST3) 4C is a diagram showing an example of a cross-sectional structure of the substrate W in step ST3. As shown in FIG. 4C, in step ST3, the film to be etched 102 is etched. Specifically, for example, a processing gas is supplied from the gas supply unit 20 into the plasma processing space 10s, and an RF signal is supplied from the RF power supply 31 to the substrate support 11. This generates plasma in the plasma processing space 10s, and ion components in the plasma are attracted to the substrate W. At this time, the tin-containing film 103 including the modified film 103a functions as a mask, and the portion of the film to be etched 102 exposed at the bottom of the opening OP is etched in the depth direction of the opening OP (from top to bottom in FIG. 4C).

[0063] The tin-containing film 103 on which the modified film 103a is formed can have improved etching resistance against the etching gas (processing gas) of the etched film 102. Therefore, when the tin-containing film 103 is used as a mask for etching the etched film 102, deformation and thickness reduction of the tin-containing film 103, scattering of tin and the like from the tin-containing film 103 onto the etched film 102, and the like are suppressed. This allows the etched film 102 to be etched more appropriately.

[0064] 5, the processing gas may be selected according to the material of each film, and each film may be etched sequentially. When the first film 102a is a spin-on-glass (SOG) film, a SiON film, a Si-containing anti-reflective coating (SiARC), or the like, the processing gas for etching may be a CF-based gas (CF, C4F6, C4F8, CHF3, CH2F2 gas, or the like). The tin-containing film 103 on which the modified film 103a is formed may have improved etching resistance against the CF-based gas that etches the film 102.

[0065] Furthermore, when at least one of the layers constituting the film to be etched 102, for example, the second film 102b, is a carbon-containing film such as a spin-on carbon (SOC) film or amorphous carbon (ACL), the etching process gas may be a hydrogen-containing gas (e.g., N2 / H2 gas) or an oxygen-containing gas (e.g., O2 / COS gas, CO2 / COS gas). When an oxygen-containing gas is used to etch the second film 102b, the tin-containing film 103 may be removed before etching the second film 102b. This prevents tin and other elements from scattering in the tin-containing film 103 during etching of the second film 102b, which requires high bias power. When a hydrogen-containing gas is used to etch the second film 102b, the tin-containing film 103 and the second film 102b may be removed simultaneously.

[0066] When the third film 102c is a silicon-containing dielectric film such as SiC, SiON, SiN, and / or SiO2, the etching process gas may be a CF-based gas (CF4, C4F6, C4F8, CHF3, CH2F2 gas, etc.). The tin-containing film 103 may be removed before etching the third film 102c. This can prevent tin and other elements from the tin-containing film 103 from scattering during etching of the third film 102c, which requires high bias power.

[0067] <Modification of this processing method> Fig. 7 is a flowchart showing a modified example of the present processing method. The modified example shown in Fig. 7 is similar to the example shown in Fig. 3 except that it further includes a step of forming a deposition film (step ST2a) after step ST2. The present processing method can be modified in various ways without departing from the scope and spirit of the present disclosure.

[0068] As shown in FIG. 7, step ST2a is performed between step ST2 and step ST3. In step ST2a, a deposited film is formed on the tin-containing film 103 on which the modified film 103a has been formed. The deposited film may be formed by plasma CVD. The processing gas in the plasma CVD may contain carbon (C), such as CH4. In this case, the deposited film is formed as a film containing carbon. The deposited film may be selectively formed on the upper surface TS of the tin-containing film 103, among the upper surface TS and side surface SS, and the exposed surface ES of the film 102 to be etched. That is, the deposited film is formed so that its deposition rate is faster on the upper surface TS than on the side surface SS and exposed surface ES.

[0069] The deposited film may be formed, for example, by the following method. First, a first gas (e.g., a silicon (Si)-containing gas) is supplied to the substrate W, and molecules of the first gas are adsorbed on at least the tin-containing film 103 to form a precursor layer. Next, a second gas (e.g., oxygen gas (O)) is supplied to the substrate W, and an RF signal is supplied from the RF power source 31 to the conductive member of the substrate support 11 and / or the conductive member of the shower head 13. The precursor layer is modified by plasma generated from this second gas, thereby forming a deposited film. A purge step may be included between the supply of the first gas and the supply of the second gas. This deposited film may be formed atomic layer by atomic layer by atomic layer deposition (ALD).

[0070] FIG. 8 shows an example of a timing chart for plasma-assisted ALD. According to FIG. 8, supply of a first gas (first gas "ON") and generation of plasma from a second gas (second gas "ON" and RF signal "ON") are alternately performed. Gas purging (gas purging "ON") may be performed between these operations. Furthermore, a subconformal deposition film may be selectively formed on the tin-containing film 103. Here, a subconformal deposition film refers to a deposition film having a different thickness along the thickness direction of the substrate. A subconformal deposition film can be formed, for example, by not allowing molecules of the first gas to adsorb on the bottom and wall of the opening OP and / or by not modifying the precursor layer formed on the bottom and wall of the opening OP. More specifically, a subconformal deposition film can be formed on the tin-containing film 103 by adjusting the supply time of the first gas or the generation time of plasma from the second gas.

[0071] The deposited film may be formed by plasma-free ALD. For example, plasma-free ALD may involve forming an organic film by a polymerization reaction between a first organic compound and a second organic compound. Examples of the first organic compound include isocyanates, carboxylic acids, carboxylic acid halides, and carboxylic acid anhydrides. Examples of the second organic compound include compounds with hydroxyl groups and amines.

[0072] FIG. 9 shows an example of a timing chart for plasma-free ALD. According to FIG. 9, the supply of a first organic compound (first gas "ON") and the supply of a second organic compound (second gas "ON") are alternately performed. Gas purging (gas purge "ON") may be performed between these. During this time, no RF signal is supplied from the RF power supply 31 to the conductive member of the substrate support 11 and / or the conductive member of the shower head 13 (RF signal "OFF"). Furthermore, a subconformal organic film may be selectively formed on the tin-containing film 103. The subconformal organic film can be formed, for example, by preventing molecules of the first organic compound from adsorbing to the bottom and wall of the opening OP and / or preventing the second organic compound from reacting with molecules of the first organic compound adsorbed to the bottom and wall of the opening OP.

[0073] FIG. 10 is a diagram showing an example of a selectively formed deposition film. As shown in FIG. 10, a deposition film 104a is selectively formed on the upper surface TS of the tin-containing film 103. The selective formation may be performed by simultaneously supplying a gas contributing to film formation, such as carbon gas, and a gas contributing to etching, such as nitrogen gas, into the plasma processing space 10s and performing plasma processing. As a result, the amount of film formation and the amount of etching cancel each other out on the side surface SS of the tin-containing film 103 and the exposed surface ES of the film to be etched 102, while the amount of film formation exceeds the amount of etching on the upper surface TS due to a loading effect or the like. As a result, no deposition film is formed on the side surface SS of the tin-containing film 103 or the exposed surface ES of the film to be etched 102, and the deposition film 104a is formed only on the upper surface TS of the tin-containing film 103.

[0074] The deposited film 104a can function as an etching mask for the film 102 to be etched together with the tin-containing film 103. That is, the thickness (vertical dimension in FIG. 10) of the etching mask used in step ST3 can be increased by the thickness of the deposited film 104a. Also, by appropriately selecting the material of the deposited film 104a, the etching resistance of the etching mask against the etching gas (processing gas) for the film 102 to be etched can be improved.

[0075] The deposited film may be formed of the same material as the material constituting the upper electrode included in the shower head 13 of the substrate processing apparatus 1. The deposited film may be selectively formed on the upper surface TS of the tin-containing film 103 on which the modified film 103a is formed, for example, by sputtering the upper electrode located above the substrate W.

[0076] 11 is a diagram showing an example of a deposited film formed by sputtering. As shown in FIG. 11, the deposited film 104b is selectively formed (so as to be thicker than the side surface SS) on the upper surface TS of the tin-containing film 103. Sputtering of the upper electrode is performed, for example, by supplying a processing gas containing a rare gas such as argon into the plasma processing space 10s to generate plasma, while applying a negative DC voltage to the shower head 13 (upper electrode) of the substrate processing apparatus 1. The plasmatized argon ions collide with the shower head 13, which has a negative potential. As a result, constituent elements (e.g., silicon) of the shower head 13 are sputtered, and deposits containing the constituent elements fall on the surface of the substrate W, forming a deposited film 104b selectively on the upper surface TS of the tin-containing film 103.

[0077] The deposited film 104b can function as an etching mask for the film 102 to be etched together with the tin-containing film 103. That is, the thickness (vertical dimension in FIG. 9) of the etching mask used in step ST3 can be increased by the thickness of the deposited film 104b. Also, by appropriately selecting the material of the deposited film 104b (constituent elements of the shower head 13), the etching resistance of the etching mask against the etching gas (processing gas) for the film 102 to be etched can be improved.

[0078] 3 and 7, a modification process similar to step ST2 may be performed one or more times. For example, during the execution of step ST3 (etching process) in FIGS. 3 and 7, the modification process may be performed at one or more timings (for example, when the etching target film 102 is etched to a predetermined depth or when a part of the film constituting the etching target film 102 is etched). In this case, reduction of the modified film 103a of the tin-containing film 103 due to etching can be suppressed. Also, for example, in the example shown in FIG. 7, the modification process may be performed between step ST2a and step ST3. Also, for example, in the example shown in FIGS. 3 and 7, the modification process of step ST2 and the etching process of step ST3 may be performed simultaneously.

[0079] In the example shown in FIG. 7, a process for forming a deposited film similar to step ST2a (hereinafter referred to as a "deposition process") may be performed one or more times. For example, during the execution of step ST3 (etching process), the deposition process may be performed at one or more timings (for example, when the etching target film 102 is etched to a predetermined depth or when a part of the film constituting the etching target film 102 is etched). The deposition process may be performed by combining multiple techniques. For example, the formation of the deposited film 104a shown in FIG. 10 and the formation of the deposited film 104b shown in FIG. 11 may be performed alternately. Furthermore, the modification process and the deposition process may be repeated alternately.

[0080] This processing method may be performed using, for example, the substrate processing system PS shown in Fig. 2. In this case, the steps shown in Fig. 3 and Fig. 7 may be performed in the same substrate processing chamber of each substrate processing module PM (substrate processing chambers PM1 to PM6), or may be performed in different substrate processing chambers. Furthermore, this processing method may be performed using a substrate processing apparatus using any plasma source, such as inductively coupled plasma or microwave plasma, other than the capacitively coupled substrate processing apparatus 1.

[0081] <Example> Next, examples of the present processing method will be described, but the present disclosure is not limited to the following examples.

[0082] A substrate W was prepared in a substrate processing apparatus 1. The substrate W had a silicon-on-silicon layer of an SOC film, an SOG film, and a tin-containing film with an opening pattern laminated in this order. The opening pattern of the tin-containing film was a line and space (L / S) pattern. Next, a modification process was performed on the tin-containing film using Cl / Ar (Example 1) or HBr / Ar (Example 2) as a processing gas.

[0083] FIG. 12 shows the results of the modification process according to the examples. FIG. 12 shows the measurement results of the film thickness (nm), line CD (nm), space CD (nm), LWR (nm), and LER (nm) of the tin-containing film 103 before and after the modification process (Examples 1 and 2). In both Examples 1 and 2, the modification process improved the roughness (LWR and LER) of the opening pattern of the tin-containing film. In Example 1, the reduction in the film thickness of the tin-containing film was suppressed compared to Example 2. When the halogen-containing gas contains hydrogen, hydrogen bonds with the tin in the tin-containing film during the modification process to generate highly volatile tin hydride, which can reduce the film thickness of the hydrogen-containing gas. Since the halogen-containing gas does not contain hydrogen in Example 1, the reduction in the film thickness of the tin-containing film 103 during the modification process is thought to be more suppressed than in Example 2. [Explanation of symbols]

[0084] 1...substrate processing apparatus, 10...plasma processing chamber, 10s...plasma processing space, 11...substrate support, 13...shower head, 20...gas supply unit, 21...gas source, 22...flow rate controller, 30...power supply, 31...RF power supply, 32...DC power supply, 40...exhaust system, 50...control unit, 101...underlying film, 102...film to be etched, 102a...first film, 102b...second film, 102c...third film, 103...tin-containing film, 103a...modified film, 104...deposited film, 105...protective film, PS...substrate processing system, W...substrate, TS...top surface, SS...side surface, ES...exposed surface, OP...opening

Claims

1. providing a substrate in a chamber, the substrate having a film to be etched and a tin-containing film defining at least one opening on the film to be etched; supplying a process gas containing a halogen-containing gas into the chamber to form a modified film containing tin-halogen bonds on the surface of the tin-containing film; A substrate processing method comprising:

2. providing a substrate in a chamber, the substrate having a film to be etched and a tin-containing film defining at least one opening on the film to be etched; supplying a process gas containing a halogen-containing gas or an oxygen-containing gas into the chamber to form a modified film on the surface of the tin-containing film; forming a deposition film on the tin-containing film after the step of forming the modified film; A substrate processing method comprising:

3. 3. The substrate processing method according to claim 2, wherein the deposited film is formed by at least one of plasma CVD and ALD.

4. The substrate processing method according to claim 2 , wherein the deposition film is selectively formed on the top surface of the tin-containing film.

5. 3. The substrate processing method according to claim 2, wherein the deposited film is formed by sputtering an upper electrode disposed above the substrate.

6. 6. The substrate processing method of claim 5, wherein the sputtering comprises generating a plasma between the substrate and the upper electrode, and applying a negative potential to the upper electrode.

7. 7. The substrate processing method according to claim 2, wherein the step of forming the deposition film and the step of forming the modified film are performed in the same chamber.

8. 8. The substrate processing method according to claim 1, wherein the step of forming the modified film includes the steps of generating plasma from the processing gas and forming the modified film on the tin-containing film by the generated plasma.

9. 8. The substrate processing method according to claim 1, wherein the step of forming the modified film includes the step of reacting the processing gas with a surface of the tin-containing film to form the modified film.

10. 10. The substrate processing method according to claim 1, further comprising the step of etching the film to be etched during or after the step of forming the modified film.

11. The method further includes a step of etching the film to be etched during or after the step of forming the modified film, 10. The substrate processing method according to claim 2, wherein the step of etching the film to be etched and the step of forming the deposition film are performed in the same chamber.

12. The substrate processing method according to claim 1 , wherein the tin-containing film is a photoresist.

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