Substrate processing method

Abstract

This invention provides a technique for modifying a tin-containing film on a substrate. In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the following steps: preparing a substrate in a chamber, the substrate having an etched film and a tin-containing film defining at least one opening on the etched film; and supplying a processing gas containing a halogen-containing gas or an oxygen-containing gas to the chamber to form a modified film on the surface of the tin-containing film.

Description

Technical Field

[0001] The exemplary embodiments of the present invention relate to a substrate processing method. Prior Technology

[0002] Patent document 1 relates to a pattern formation method in a semiconductor device, and discloses a technique that uses a thinner tin oxide film as an etching mask. [Previous Technical Documents] [Patent Literature]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-6742 Summary of the Invention

[0004] [The problem the invention aims to solve]

[0005] This invention provides a technique for modifying a tin-containing film on a substrate. [Technical means to solve the problem]

[0006] In one embodiment of the present invention, a substrate processing method is provided. The substrate processing method includes the following steps: preparing a substrate in a chamber, the substrate having an etchable film and a tin-containing film defining at least one opening on the etchable film; and supplying a processing gas containing a halogen-containing gas or an oxygen-containing gas to the chamber to form a modified film on the surface of the tin-containing film. [Effects of the Invention]

[0007] According to an exemplary embodiment of the present invention, a technique for modifying a tin-containing film on a substrate can be provided. Simple Explanation of the Diagram

[0008] Figure 1 is a schematic diagram of the substrate processing apparatus 1. Figure 2 is a schematic diagram of the substrate processing system PS. Figure 3 is a flowchart illustrating this processing method. Figure 4A shows an example of the cross-sectional structure of the substrate W prepared in step ST1. Figure 4B shows an example of the cross-sectional structure of the substrate W in step ST2. Figure 4C shows an example of the cross-sectional structure of the substrate W in step ST3. Figure 5 shows another example of the cross-sectional structure of substrate W. Figure 6 shows another example of the third membrane 102c in Figure 5. Figure 7 is a flowchart showing a variation of this processing method. Figure 8 is a timing diagram of an example of ALD (Atomic Layer Deposition) using plasma. Figure 9 shows an example of a timing diagram for an ALD without plasma. Figure 10 shows an example of a selectively formed deposition film. Figure 11 shows an example of a deposited film formed by sputtering. Figure 12 is a diagram showing the results of the modification treatment in the embodiment. Implementation

[0009] The various embodiments of the present invention will be described below.

[0010] In one exemplary embodiment, a substrate processing method is provided. The substrate processing method includes the following steps: preparing a substrate in a chamber, the substrate having an etched film and a tin-containing film defining at least one opening on the etched film; and supplying a processing gas containing a halogen-containing gas or an oxygen-containing gas to the chamber to form a modified film on the surface of the tin-containing film.

[0011] In one exemplary embodiment, the process of forming the modified film may include: a process of generating plasma from the process gas; and a process of forming the modified film on the tin-containing film by means of the generated plasma.

[0012] In one exemplary embodiment, the process of forming the modified film may include a process of reacting the processing gas with the surface of the tin-containing film to form the modified film.

[0013] In one exemplary embodiment, the modified membrane may contain tin-halogen bonds.

[0014] In one exemplary embodiment, after the step of forming the modified film, a step of forming a deposited film on the tin-containing film may be further included.

[0015] In one exemplary embodiment, the deposited film can be formed by plasma CVD (Chemical Vapor Deposition).

[0016] In one exemplary embodiment, the deposited film may be selectively formed on the surface above the tin-containing film.

[0017] In one exemplary embodiment, the deposition film can be formed by sputtering an upper electrode disposed above a substrate.

[0018] In one exemplary embodiment, sputtering may include: generating plasma between the substrate and the upper electrode; and setting the upper electrode to a negative potential.

[0019] In one exemplary embodiment, the process of forming the deposited film and the process of forming the modified film can be performed in the same chamber.

[0020] In one exemplary embodiment, after the step of forming the modified film, a step of etching the etched film may be further included.

[0021] In one exemplary embodiment, the etching process of the etched film and the formation of the deposited film can be performed in the same chamber.

[0022] In one exemplary embodiment, the tin-containing film may be a photoresist.

[0023] Hereinafter, various embodiments of the present invention will be described in detail with reference to the drawings. Furthermore, in each drawing, the same element or identical elements are labeled with the same symbol, and repeated descriptions are omitted. Unless otherwise specified, the positional relationships (top, bottom, left, right, etc.) shown in the drawings are explained based on the positional relationships depicted. The scale ratios in the drawings do not represent actual ratios, and actual ratios are not limited to those shown in the drawings.

[0024] <Composition of Substrate Processing Device 1> Figure 1 is a schematic diagram illustrating a substrate processing apparatus 1 according to an exemplary embodiment. A substrate processing method (hereinafter referred to as "this processing method") according to an exemplary embodiment can be performed using the substrate processing apparatus 1.

[0025] 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. Furthermore, the substrate 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 cluster nozzle 13. The substrate support unit 11 is disposed within the plasma processing chamber 10. The cluster nozzle 13 is disposed above the substrate support unit 11. In an exemplary embodiment, the cluster nozzle 13 constitutes at least a portion of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the cluster nozzle 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 has at least one gas supply port for supplying at least one type of processing gas to the plasma processing space 10s, and at least one gas outlet for discharging gas from the plasma processing space. The sidewall 10a is grounded. The cluster nozzle 13 and the substrate support portion 11 are electrically insulated from the housing of the plasma processing chamber 10.

[0026] The substrate support portion 11 includes a body portion 111 and a ring assembly 112. The body portion 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 body portion 111 surrounds the central region 111a of the body portion 111 in a top view. The substrate W is disposed on the central region 111a of the body portion 111, and the ring assembly 112 is disposed on the annular region 111b of the body portion 111 in a manner that surrounds the substrate W on the central region 111a of the body portion 111. In an exemplary embodiment, the body portion 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 annular members is an edge ring. Also, although not shown in the figures, the substrate support 11 may include a temperature control module configured to adjust at least one of the electrostatic chuck, ring assembly 112, and 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 in the flow path. Furthermore, the substrate support 11 may include a heat transfer gas supply section configured to supply heat transfer gas between the back surface of the substrate W and the substrate support surface 111a.

[0027] The cluster injector 13 is configured to introduce at least one type of processing gas from the gas supply unit 20 into the plasma processing space 10s. The cluster injector 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and a plurality of gas inlets 13c. The processing gas supplied to the gas supply port 13a is introduced into the plasma processing space 10s through the gas diffusion chamber 13b and the plurality of gas inlets 13c. Furthermore, the cluster injector 13 includes a conductive member. The conductive member of the cluster injector 13 functions as an upper electrode. Moreover, in addition to the cluster injector 13, the gas inlet unit may also include one or more side gas injectors (SGIs), which are installed in one or more openings formed on the sidewall 10a.

[0028] 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 type of processing gas from its respective gas source 21 to the cluster nozzle 13 via its respective flow controller 22. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Furthermore, the gas supply unit 20 may include one or more flow modulation devices for modulating or pulsedizing the flow rate of the at least one type of processing gas.

[0029] The power supply 30 includes an RF (Radio Frequency) 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 portion 11 and / or the conductive members of the cluster nozzle 13. Thereby, plasma is formed from at least one processing gas supplied to the plasma processing space 10s. Therefore, the RF power supply 31 can function as at least part of a plasma generation unit configured to generate plasma from one or more processing gases in the plasma processing chamber 10. Furthermore, by supplying a bias RF signal to the conductive members of the substrate support portion 11, a bias potential is generated on the substrate W, which can feed the ionic components of the formed plasma into the substrate W.

[0030] In one exemplary embodiment, the RF power supply 31 includes a first RF generation unit 31a and a second RF generation unit 31b. The first RF generation unit 31a is configured to couple with the conductive members of the substrate support 11 and / or the conductive members of the cluster emitter 13 via at least one impedance matching circuit 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 generation unit 31a may be configured to generate a plurality of source RF signals with 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 cluster emitter 13. The second RF generation unit 31b is configured to couple with the conductive members of the substrate support 11 via at least one impedance matching circuit 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 generation unit 31b may be configured to generate a plurality of bias RF signals with different frequencies. One or more of the generated bias RF signals are supplied to the conductive members of the substrate support unit 11. Furthermore, in various embodiments, at least one of the source RF signal and the bias RF signal can be pulsed.

[0031] Furthermore, the power supply 30 may include a DC (Direct Current) 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 exemplary embodiment, the first DC generation unit 32a is configured to be connected to a conductive member of the substrate support 11 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 other electrodes, such as electrodes within an electrostatic chuck. In one exemplary embodiment, the second DC generation unit 32b is configured to be connected to a conductive member of the cluster head 13 to generate a second DC signal. The generated second DC signal is applied to the conductive member of the cluster head 13. In various embodiments, at least one of the first and second DC signals may be pulsed. Furthermore, the first and second DC generating units 32a and 32b can also be added to the RF power supply 31, and the first DC generating unit 32a can also replace the second RF generating unit 31b.

[0032] The exhaust system 40 may be connected, for example, to a gas outlet 10e located at the bottom of the plasma processing chamber 10. The exhaust system 40 may include a pressure regulating valve and a vacuum pump. The pressure within the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry vacuum pump, or a combination thereof.

[0033] The control unit 50 processes computer-executable commands that cause the substrate processing apparatus 1 to perform the various processes described herein. The control unit 50 may be configured to control various elements of the substrate processing apparatus 1 in a manner that executes the various processes described herein. In one exemplary embodiment, part or all of the control unit 50 may be configured as part of an external device of the substrate processing apparatus 1. The control unit 50 may, for example, include a computer 50a. The computer 50a may, for example, include 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 actions based on a program stored in the memory unit 50a2. The memory unit 50a2 may include RAM (Random Access Memory), ROM (Read Only Memory), HDD (Hard Disk Drive), SSD (Solid State Drive), or a combination thereof. The communication interface 50a3 can communicate with other components of the substrate processing device 1 via communication lines such as LAN (Local Area Network).

[0034] <Composition of the PS Substrate Processing System> Figure 2 is a schematic diagram of a substrate processing system PS according to an exemplary embodiment. This processing method can be performed using the substrate processing system PS.

[0035] The substrate processing system PS includes substrate processing chambers PM1 to PM6 (hereinafter collectively referred to as "substrate processing modules PM"), a transport module TM, loading latch modules LLM1 and LLM2 (hereinafter collectively referred to as "loading latch modules LLM"), a carrier module LM, and load ports LP1 to LP3 (hereinafter collectively referred to as "load ports LP"). The control unit CT controls each component of the substrate processing system PS to perform specific processing on the substrate W.

[0036] The substrate processing module PM performs etching, trimming, film formation, annealing, doping, photolithography, cleaning, and ashing processes on the substrate W. A portion of the substrate processing module PM can be a measurement module, capable of measuring the film thickness or the dimensions of patterns formed on the substrate W. The substrate processing apparatus 1 shown in Figure 1 is an example of a substrate processing module PM.

[0037] The transport module TM has a transport device for transporting substrates W, which transports substrates W between substrate processing modules PM or between substrate processing modules PM and loading lock-up modules LLM. The substrate processing modules PM and loading lock-up modules LLM are arranged adjacent to the transport module TM. The transport module TM is spatially isolated from or connected to the substrate processing modules PM and loading lock-up modules LLM by openable and closable gate valves.

[0038] Loading interlocking modules LLM1 and LLM2 are located between the transfer module TM and the carrier module LM. The loading interlocking module LLM can switch its internal pressure to atmospheric pressure or vacuum. The loading interlocking module LLM transfers the substrate W from the carrier module LM (at atmospheric pressure) to the transfer module TM (vacuum), and also transfers it from the transfer module TM (vacuum) to the carrier module LM (at atmospheric pressure).

[0039] The carrier module LM has a conveying device for transporting substrates W between the loading latch module LLM and the load port LP. The interior of the load port LP can, for example, hold a FOUP (Front Opening Unified Pod) capable of holding 25 substrates W or an empty FOUP. The carrier module LM removes substrates W from the FOUP in the load port LP and transports them to the loading latch module LLM. Similarly, the carrier module LM removes substrates W from the loading latch module LLM and transports them to the FOUP in the load port LP.

[0040] The control unit CT controls each component of the substrate processing system PS to perform specific processing on the substrate W. The control unit CT stores a formula that sets the process steps, process conditions, transport conditions, etc., and controls each component of the substrate processing system PS to perform specific processing on the substrate W according to the formula. The control unit CT may also have some or all of the functions of the control unit 50 of the substrate processing apparatus 1 shown in FIG. 1.

[0041] <An example of this processing method> Figure 3 is a flowchart illustrating the processing method. As shown in Figure 3, the processing method includes a step of preparing the substrate W (step ST1), a step of forming a modified film (step ST2), and a step of performing etching (step ST3).

[0042] Hereinafter, referring to Figures 4A-4C, 5, and 6, an example of the processing method shown in Figure 3 will be shown. The following description will illustrate the case where the control unit 50 controls each part of the board processing apparatus 1 (refer to Figure 1) to execute the processing method.

[0043] (Preparation of substrate W: Step ST1) Figure 4A shows an example of the cross-sectional structure of the substrate W prepared in step ST1. In ST1, the substrate W is prepared within the plasma processing space of the plasma processing chamber 10 for 10 seconds. Within the plasma processing space for 10 seconds, the substrate W is placed on the substrate support surface 111a of the substrate support portion 11 and held by an electrostatic chuck. At least a portion of the process for forming each component of the substrate W can be performed within the plasma processing space for 10 seconds. Alternatively, the substrate W can be placed within the plasma processing space for 10 seconds after all or part of each component of the substrate W has been formed in a device or chamber outside the substrate processing apparatus 1.

[0044] The substrate W prepared in step ST1 is formed by sequentially depositing a base film 101, an etched film 102, and a tin-containing film 103.

[0045] The substrate film 101 may be, for example, a silicon wafer or an organic film, dielectric film, metal film, semiconductor film, etc., formed on a silicon wafer. The substrate film 101 may be composed of multiple layers.

[0046] The etched film 102 can be, for example, an organic film, a dielectric film, a semiconductor film, or a metal film. The etched film 102 can be composed of a single film, or it can be composed of multiple films stacked together.

[0047] The tin-containing film 103 may contain, for example, tin oxide and / or tin hydroxide. The tin-containing film 103 may contain organic matter, such as a photoresist.

[0048] The various films constituting the substrate W (base film 101, etched film 102, tin-containing film 103) can be formed by CVD, ALD, spin coating, etc. The above films can be flat films or films with irregularities.

[0049] 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 (e.g., vertical). The tin-containing film 103 has an opening pattern. The opening pattern defines at least one opening OP on the etched film 102. The opening OP is a space on the etched film 102 and is surrounded by the side surface SS of the tin-containing film 103. The etched film 102 has an area covered by the tin-containing film 103 and an area exposed at the bottom of the opening OP.

[0050] The opening pattern of the tin-containing film 103 can have any shape when viewed from above on the substrate W (when viewing the substrate W from the direction of looking down from above in Figure 4A). For example, the opening pattern can be a plurality of lines and gaps (L / S) arranged at fixed intervals in the shape of the opening OP in the top view, or it can be an array pattern of a plurality of holes in the shape of circles, ellipses, rectangles, etc. arranged in the top view.

[0051] The opening pattern of the tin-containing film 103 can be formed, for example, by photolithography. Specifically, for example, firstly, a tin-containing photoresist film is formed on the etched film 102. Then, using an exposure mask, light (e.g., EUV (Extreme Ultraviolet) excimer laser) is selectively irradiated onto the photoresist film, exposing the opening pattern on the photoresist film. Subsequently, the exposed photoresist film is developed. This forms the tin-containing film 103 with the opening pattern. When the opening pattern is a line-and-spacing (L / S) pattern, for example, a half-pitch of 18 nm can be used. Alternatively, the opening pattern of the tin-containing film 103 can be formed by etching.

[0052] Furthermore, the substrate W prepared in step ST1 can take various forms. Figure 5 shows another example of the cross-sectional structure of the substrate W. As shown in Figure 5, the etched film 102 can be constructed by stacking multiple films, and can have a first film 102a, a second film 102b, and a third film 102c. The etching characteristics of the first film 102a, the second film 102b, and the third film 102c can be different. The tin-containing film 103, the first film 102a, and the second film 102b can form a three-layer multilayer photomask relative 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.

[0053] The first film 102a is, for example, a spin-coated glass (SOG) film, a SiON film, or a Si-containing antireflective film (SiARC). The first film 102a can be formed by laminating multiple films, for example, by laminating an antireflective film (BARC) onto a SiON film.

[0054] The second film 102b is, for example, a spin-coated carbon (SOC) film, an amorphous carbon layer (ACL), or other carbon-containing films.

[0055] The third film 102c can be a silicon-containing dielectric film such as SiC, SiON, SiN, and / or SiO2. The third film 102c can be formed by stacking multiple films, for example, by stacking multiple silicon oxide films or silicon nitride films.

[0056] Figure 6 shows another example of the third film 102c in Figure 5. As shown in Figure 6, the third film 102c can have a plurality of films (SiN film 102c1, SiO film 102c2, SiC film 102c3) arranged in a specific order in a direction perpendicular to the stacking direction (the left-right direction in Figure 6). Any one of the SiN film 102c1, SiO film 102c2, and SiC film 102c3 can be selectively etched.

[0057] (Formation of modified membrane: Step ST2) Figure 4B is a diagram showing an example of the cross-sectional structure of the substrate W in step ST2. As shown in Figure 4B, in step ST2, a modified film 103a is formed on the tin-containing film 103 (hereinafter also referred to as "modification treatment"). Specifically, firstly, a processing gas containing halogen-containing gas or oxygen-containing gas is supplied from the gas supply unit 20 to the plasma processing space for 10 seconds.

[0058] Halogen-containing gases may include one or more gases composed of molecules containing F, Cl, Br, or I, such as CHF₃, CF₄, NF₃, SF₆, IF₇, HF, HBr, Cl₂, BCl₃, Br₂, SiF₄, and / or SiCl₄. As halogen-containing gases, gases composed of molecules that do not contain H (hydrogen) can be used (in the above examples, CF₄, NF₃, SF₆, IF₇, Cl₂, BCl₃, Br₂, SiF₄, and / or SiCl₄). Oxygen-containing gases may include one or more gases composed of molecules containing O, such as CO, O₂, CO₂, O₃, NO, NO₂, SO₂, and / or COS. The processing gas may include noble gases such as Ar and inert gases such as N₂.

[0059] Next, an RF signal is supplied from the RF power supply 31 to the plasma processing space for 10 seconds, and a plasma of the processing gas is generated in the plasma processing space for 10 seconds. The ions or free radicals in the generated plasma form chemical bonds with the tin on the surface (upper surface TS and side surface SS) and near the surface of the tin-containing film 103 (hereinafter collectively referred to as "surface etc"), and form a modified film 103a on the surface etc of the tin-containing film 103.

[0060] The modification process does not require the use of plasma. That is, a processing gas containing halogen-containing or oxygen-containing gases can be supplied from the gas supply unit 20 to the plasma processing space within 10 seconds, allowing the processing gas to react directly with the surface of the tin-containing film 103 to form a modified film 103a. Even without plasmaification (even in the state of a raw material gas), the processing gas can contain highly reactive gases such as HF, IF, and O3. Furthermore, the processing gas can be endowed with thermal energy, electromagnetic wave energy, light energy, and other energies to enhance its reactivity.

[0061] When processing gases containing halogenated gases, the modified film 103a contains tin halide (tin-halogen bonds). When processing gases containing oxygen-containing gases, the modified film 103a, compared to other parts of the tin-containing film 103, promotes tin oxidation and contains more tin oxide (or tin-oxygen bonds). The bonding energy of tin-halogen bonds or tin-oxygen bonds is higher than that of tin-tin bonds. Therefore, tin halide or tin oxide with more tin-halogen bonds or tin-oxygen bonds has a higher melting point and boiling point, and is thermally stable compared to tin halide or tin oxide with fewer tin-halogen bonds or tin-oxygen bonds. Therefore, compared to other parts of the tin-containing film 103, the modified film 103a becomes more thermally or chemically stable, and its chemical resistance, such as plasma resistance, is improved. For example, compared to a tin-containing film 103 without modified film 103a, a tin-containing film 103 with modified film 103a exhibits improved resistance to etching or corrosion by etching gases used to etch the film 102 (the etching rate can be reduced). Modified film 103a has, for example, a thickness of 1 to 2 nm. Modified film 103a can be formed on all or part of the surface of the tin-containing film 103.

[0062] Furthermore, through the modification treatment, the modified film 103a, compared to other parts of the tin-containing film 103, can reduce hardening and / or impurity content. This improves the chemical resistance of the tin-containing film 103. Also, through the modification treatment, the size / shape of the opening pattern of the tin-containing film 103 can be made more uniform compared to before the modification treatment. For example, when the opening pattern is a line and gap (L / S) pattern, the line edge roughness (LER) or line width roughness (LWR) can be improved.

[0063] (Etching process: Step ST3) Figure 4C shows an example of the cross-sectional structure of the substrate W in step ST3. As shown in Figure 4C, in step ST3, the etched film 102 is etched. Specifically, for example, processing gas is supplied from the gas supply unit 20 to the plasma processing space for 10 seconds, and an RF signal is supplied from the RF power supply 31 to the substrate support unit 11. Hereby, plasma is generated in the plasma processing space for 10 seconds, and the ionic components in the plasma are fed into the substrate W. At this time, the tin-containing film 103, including the modified film 103a, functions as a photomask, etching the portion of the etched film 102 exposed at the bottom of the opening OP in the depth direction of the opening OP (the direction from top to bottom in Figure 4C).

[0064] The tin-containing film 103 with the modified film 103a formed can improve the etching resistance to the etching gas (processing gas) of the film to be etched 102. Therefore, when the tin-containing film 103 is used as a photomask for etching the film to be etched 102, deformation of the tin-containing film 103 or reduction of film thickness, and tin and other materials flying from the tin-containing film 103 onto the film to be etched 102 are suppressed. As a result, the film to be etched 102 can be etched more appropriately.

[0065] Furthermore, when the etched film 102 has a multilayer structure as shown in Figure 5, the processing gas can be selected according to the material of each film, and each film can be etched sequentially. When the first film 102a is a spin-coated glass (SOG) film, a SiON film, a Si-containing anti-reflective film (SiARC), etc., the etching processing gas can be a CF-based gas (CF4, C4F6, C4F8, CHF3, CH2F2, etc.). The tin-containing film 103 with the modified film 103a can improve the etching resistance to CF-based gases used to etch the etched film 102.

[0066] Furthermore, when at least one of the multiple layers constituting the etched film 102, such as the second film 102b, is a spin-coated carbon (SOC) film, an amorphous carbon layer (ACL), or other carbon-containing film, the etching process gas can be a hydrogen-containing gas (N2 / H2 gas, etc.) or an oxygen-containing gas (O2 / COS gas, CO2 / COS gas, etc.). When using an oxygen-containing gas for etching the second film 102b, the tin-containing film 103 can be removed before etching the second film 102b. This can suppress the tin and other components of the tin-containing film 103 from scattering during the etching of the second film 102b, which requires a higher bias voltage. When using a hydrogen-containing gas for etching the second film 102b, both the tin-containing film 103 and the second film 102b can be removed simultaneously.

[0067] When the third film 102c is a silicon-containing dielectric film such as SiC, SiON, SiN, and / or SiO2, the etching process gas can be a CF-based gas (CF4, C4F6, C4F8, CHF3, CH2F2, etc.). The tin-containing film 103 can be removed before etching the third film 102c. This can suppress the tin and other components in the tin-containing film 103 from scattering during the etching of the third film 102c, which requires a higher bias voltage.

[0068] <Example of a variation of this processing method> Figure 7 is a flowchart illustrating a variation of the present processing method. The variation shown in Figure 7 is identical to the example shown in Figure 3, except that it includes a step (step ST2a) after step ST2 to form a deposited film. Various modifications can be made to this processing method without departing from the scope and spirit of the invention.

[0069] As shown in Figure 7, step ST2a is performed between steps ST2 and ST3. In step ST2a, a deposition film is formed on the tin-containing film 103 on which the modified film 103a is formed. The deposition film can be formed by plasma CVD. The processing gas in plasma CVD may contain carbon (C) such as CH4. In this case, the deposition film is formed as a carbon-containing film. The deposition film can be selectively formed on the upper surface TS and side surface SS of the tin-containing film 103, as well as on the upper surface TS of the exposed surface ES of the etched film 102. That is, the deposition film is formed such that the deposition rate is faster on the upper surface TS than on the side surface SS and the exposed surface ES.

[0070] The deposited film can be formed, for example, by the following method. First, a first gas (e.g., silicon (Si) gas) is supplied to the substrate W, causing the molecules of the first gas to adsorb onto at least the tin-containing film 103, forming a precursor layer. Second, a second gas (e.g., oxygen (O2)) is supplied to the substrate W, and an RF signal is supplied from the RF power supply 31 to the conductive components of the substrate support 11 and / or the conductive components of the cluster head 13. The precursor layer is modified using plasma generated by the second gas, thereby forming the deposited film. A purge process can also be included between the supply of the first gas and the supply of the second gas. The method of forming one atomic layer at a time can also be ALD (Atomic Layer Deposition).

[0071] Figure 8 is a timing diagram illustrating an example of an ALD using plasma. According to Figure 8, the supply of the first gas (first gas "on") and the generation of plasma from the second gas are performed alternately (second gas "on" and RF signal "on"). Furthermore, gas blowing (gas blowing "on") can also be performed between these processes. Furthermore, a sub-conformal deposition film can be selectively formed on the tin-containing film 103. Here, a sub-conformal deposition film refers to a deposition film with a different thickness along the thickness direction of the substrate. The sub-conformal deposition film can be formed, for example, by preventing the molecules of the first gas from adsorbing onto the bottom and walls of the opening OP, and / or by forming a precursor layer on the bottom and walls of the opening OP without modification. More specifically, for example, a sub-conformal deposition film can be formed on the tin-containing film 103 by adjusting the supply time of the first gas or adjusting the generation time of plasma from the second gas.

[0072] The deposited film can also be formed by an ALD that does not use plasma. For example, an ALD that does not use plasma can be formed by a method of forming an organic film through polymerization reaction with a first organic compound and a second organic compound. Examples of the first organic compound include isocyanates, carboxylic acids, carboxylic acid halides, and carboxylic anhydrides. Examples of the second organic compound include compounds having hydroxyl groups and amines.

[0073] Figure 9 is an example of a timing diagram for an ALD without plasma. According to Figure 9, the supply of the first organic compound (first gas "on") and the supply of the second organic compound (second gas "on") are performed alternately. Furthermore, gas blowing (gas blowing "on") can also be performed between these processes. During this period, RF signals are not supplied from the RF power supply 31 to the conductive components of the substrate support 11 and / or the conductive components of the cluster head 13 (RF signal "off"). Furthermore, a subconformal organic film can 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 onto the bottom and walls of the opening OP, and / or preventing the second organic compound from reacting with molecules of the first organic compound adsorbed onto the bottom and walls of the opening OP.

[0074] Figure 10 illustrates an example of a selectively formed deposition film. As shown in Figure 10, a deposition film 104a is selectively formed on the upper surface TS of the tin-containing film 103. Selective formation can be performed, for example, by simultaneously supplying a gas that aids film formation, such as carbon gas, and a gas that aids etching, such as nitrogen gas, to the plasma processing space 10s, and performing plasma processing. In this way, the amount of film formed and the amount of etching cancel each other out on the side surface SS of the tin-containing film 103 or the exposed surface ES of the etched film 102. On the other hand, on the upper surface TS, due to loading effects, the amount of film formed becomes greater than the amount of etching. 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 etched film 102, but only on the upper surface TS of the tin-containing film 103.

[0075] The deposited film 104a, together with the tin-containing film 103, can function as an etching mask for the film 102 to be etched. That is, the thickness of the etching mask used in step ST3 (the size in the vertical direction in FIG. 10) can be increased by the thickness of the deposited film 104a. Furthermore, by appropriately selecting the material of the deposited film 104a, the etching resistance of the etching mask to the etching gas (processing gas) of the film 102 to be etched can be improved.

[0076] The deposited film can be formed from the same material as the material of the upper electrode included in the cluster head 13 constituting the substrate processing apparatus 1. For example, the deposited film can be selectively formed on the surface TS of the tin-containing film 103 on which the modified film 103a is formed by sputtering the upper electrode located above the substrate W.

[0077] Figure 11 illustrates an example of a deposited film formed by sputtering. As shown in Figure 11, the deposited film 104b is selectively formed (in such a way that it becomes thicker than the side surface SS) on the upper surface TS of the tin-containing film 103. The sputtering of the upper electrode is performed, for example, by supplying a processing gas containing a rare gas such as argon to the plasma processing space for 10s to generate plasma, and applying a negative DC voltage to the cluster head 13 (upper electrode) of the substrate processing apparatus 1. The plasma-generated argon ions collide with the cluster head 13, which has become negatively potentialed. Thereby, the constituent elements (e.g., silicon) of the cluster head 13 are sputtered, and the deposit containing the constituent elements falls onto the surface of the substrate W, selectively forming the deposited film 104b on the upper surface TS of the tin-containing film 103.

[0078] The deposited film 104b, together with the tin-containing film 103, can function as an etching mask for the film 102 to be etched. That is, the thickness of the etching mask used in step ST3 (the size in the vertical direction in FIG9) can be increased by the amount of thickness of the deposited film 104b. Furthermore, by appropriately selecting the material of the deposited film 104b (the constituent elements of the cluster head 13), the etching resistance of the etching mask to the etching gas (processing gas) of the film 102 to be etched can be improved.

[0079] In the examples shown in Figures 3 and 7, the same modification process as step ST2 can be performed once or multiple times. For example, in the execution of step ST3 (etching process) in Figures 3 and 7, the modification process can be performed at one or more time points (e.g., when the etched film 102 is etched to a specific depth or when a portion of the etched film 102 is etched). In this case, the reduction of the modified film 103a of the tin-containing film 103 caused by etching can be suppressed. Also, for example, in the example shown in Figure 7, the modification process can be performed between step ST2a and step ST3. Also, for example, in the examples shown in Figures 3 and 7, the modification process of step ST2 and the etching process of step ST3 can also be performed simultaneously.

[0080] In the example shown in Figure 7, the same process as step ST2a for forming a deposited film (hereinafter referred to as "deposition process") can be performed once or multiple times. For example, during the execution of step ST3 (etching process), the deposition process can be performed at one or multiple time points (e.g., when the etched film 102 is etched to a specific depth or when a portion of the etched film 102 is etched). Multiple methods can be combined in the deposition process. For example, the formation of the deposited film 104a shown in Figure 10 and the formation of the deposited film 104b shown in Figure 11 can be performed alternately. Furthermore, the modification process and the deposition process can be performed alternately and repeatedly.

[0081] This processing method can be performed, for example, using the substrate processing system PS shown in Figure 2. In this case, the steps shown in Figures 3 and 7 can be performed in the same substrate processing chamber of the substrate processing module PM (substrate processing chambers PM1 to PM6), or in different substrate processing chambers. Furthermore, in addition to using the capacitively coupled substrate processing apparatus 1, this processing method can also be performed using a substrate processing apparatus utilizing any plasma source such as inductively coupled plasma or microwave plasma.

[0082] <Example> Next, embodiments of this processing method will be described. This invention is not limited to any of the following embodiments.

[0083] A substrate W is prepared in a substrate processing apparatus 1. On the substrate W, a SOC film, an SOG film, and a tin-containing film with an opening pattern are sequentially deposited on silicon. The opening pattern of the tin-containing film is a line and gap (L / S) pattern. Next, the tin-containing film is modified using Cl₂ / Ar (Example 1) or HBr / Ar (Example 2) as processing gases.

[0084] Figure 12 is a graph showing the results of the modification treatment in the examples. Figure 12 shows the measurement results of the film thickness (nm), critical dimension (CD) (nm), spacing CD (nm), LWR (nm), and LER (nm) of the tin-containing film 103 before and after the modification treatment (Examples 1 and 2). In Examples 1 and 2, the roughness (LWR and LER) of the opening pattern of the tin-containing film was improved by the modification treatment. Compared with Example 2, the reduction in the film thickness of the tin-containing film was suppressed in Example 1. In the case where the halogen gas contains hydrogen, highly volatile tin hydride is generated by bonding with tin in the tin-containing film during the modification treatment, which can reduce the film thickness of the hydrogen-containing gas. Since the halogen gas in Example 1 does not contain hydrogen, it is believed that the reduction in film thickness accompanying the modification treatment of the tin-containing film 103 was suppressed compared with Example 2.

[0085] 1: Substrate processing device 10: Plasma treatment chamber 10a: Sidewall 10e: Gas exhaust outlet 10s: Plasma processing space 11:Substrate support department 13: Cluster Head 13a: Gas supply port 13b: Gas diffusion chamber 13c: Gas inlet 20: Gas Supply Department 21: Gas Source 22: Flow controller 30: Power supply 31: RF power supply 31a: 1st RF Generation Unit 31b: 2nd RF Generation Unit 32: DC power supply 32a: First DC Generation Unit 32b: Second DC Generation Unit 40: Exhaust System 50: Control Department 50a: Computer 50a1: Processing Department 50a2: Memory Department 50a3: Communication Interface 101: Basement membrane 102: Etched film 102a: First membrane 102b: Second membrane 102c: Third membrane 102c1:SiN film 102c2:SiO film 102c3:SiC film 103: Tin-containing film 103a: Modified membrane 104: Deposited film 104a: Deposited film 104b: Deposited film 105: Protective film 111: Ontology Department 111a: Central Region 111b: Annular region 112: Ring Assembly CT: Control Unit ES: Exposed LLM: Loading Lockout Module LLM1, LLM2: Loading interlocking modules LM: Carrier Module LP: Load Port LP1, LP2, LP3: Load ports OP: Open PM: Substrate Processing Module PM1, PM2, PM3, PM4, PM5, PM6: Substrate Processing Room PS: Substrate processing system SS: Side view ST1: Steps ST2: Steps ST3: Steps TM: Transport Module TS: Upper surface W: substrate

Claims

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

2. The substrate processing method of claim 1, wherein the step of forming the modified film includes: The process of generating plasma from the above-mentioned treated gas; and the process of forming the modified film on the above-mentioned tin-containing film by means of the plasma generated above.

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

4. The substrate processing method of any one of claims 1 to 3, wherein after the step of forming the modified film, the method further includes the step of forming a deposition film on the tin-containing film.

5. The substrate processing method of claim 4, wherein the deposited film is formed by at least one of plasma CVD and ALD.

6. The substrate processing method of claim 4, wherein the deposited film is selectively formed on the surface above the tin-containing film.

7. The substrate processing method of claim 4, wherein the above-deposited film is formed by sputtering an upper electrode disposed above the substrate.

8. The substrate processing method as described in claim 7, wherein the sputtering includes: Plasma is generated between the substrate and the upper electrode; and the upper electrode is made to have a negative potential.

9. The substrate processing method of claim 4, wherein the process of forming the above-mentioned deposited film and the process of forming the above-mentioned modified film are performed in the same chamber.

10. The substrate processing method of claim 4, wherein the process of forming the modified film or after the process of forming the modified film further includes a process of etching the etched film.

11. The substrate processing method of claim 10, wherein the etching process of the etched film and the deposition process are performed in the same chamber.

12. The substrate processing method of any one of claims 1 to 3, wherein the tin-containing film is a photoresist.

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