Substrate processing method and substrate processing device

Abstract

Provided are a substrate processing method and a substrate processing device for improving a pattern of a photoresist film.　This substrate processing method comprises: a step of preparing a substrate that has a photoresist film containing a metal oxide containing a first metal element; a step of forming an opening pattern in the photoresist film, by subjecting the substrate to an exposure process and a development process; and a step of forming a metal oxide film containing a second metal element that is different from the first metal element on a side wall of the photoresist film, by supplying a metal-containing gas containing the second metal element to the substrate.

Description

Substrate processing method and substrate processing apparatus

[0001] The present disclosure relates to a substrate processing method and a substrate processing apparatus.

[0002] Patent Document 1 discloses a substrate processing method including a deposition step of depositing a deposition layer on exposed surfaces including vertical sidewalls of an etch mask feature, and an etching step of etching back the deposition layer while selectively leaving the deposition on the vertical sidewalls.

[0003] Special Publication No. 2008-524851

[0004] In one aspect, the present disclosure provides a substrate processing method and a substrate processing apparatus for improving a pattern of a photoresist film.

[0005] In order to solve the above problem, a substrate processing method is provided, which includes the steps of preparing a substrate having a photoresist film containing a metal oxide containing a first metal element, subjecting the substrate to an exposure process and a development process to form an opening pattern in the photoresist film, and supplying a metal-containing gas containing a second metal element different from the first metal element to the substrate to form a metal oxide film containing the second metal element on the sidewall of the photoresist film.

[0006] According to one aspect, it is possible to provide a substrate processing method and a substrate processing apparatus for improving a pattern of a photoresist film.

[0007] 1 is a flowchart illustrating an example of a substrate processing method according to an embodiment of the present invention; 2 is an example of a schematic cross-sectional view of a substrate in each process; 3 is an example of a schematic cross-sectional view of a substrate in each process; 4 is an example of a schematic cross-sectional view of a substrate in each process; 5 is an example of a schematic cross-sectional view of a substrate in each process; 6 is a schematic view illustrating an example of a substrate processing apparatus; 7 is a flowchart illustrating an example of a film formation process in a substrate processing apparatus; 8 is an example of a schematic cross-sectional view of a photoresist film; 9 is an example of a schematic cross-sectional view of a photoresist film; 10 is an example of a schematic cross-sectional view of a photoresist film;

[0008] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same components are denoted by the same reference numerals, and redundant explanations may be omitted.

[0009] An example of a substrate processing method according to this embodiment will be described with reference to Fig. 1 and Fig. 2A to Fig. 2D. Fig. 1 is a flowchart showing an example of the substrate processing method according to this embodiment. Fig. 2A to Fig. 2D are example schematic cross-sectional views of a substrate in each process.

[0010] In step S101, a substrate is prepared. Here, the prepared substrate includes an underlayer film 310 (see FIG. 2A ). The underlayer film 310 is a film disposed under a photoresist film 320 (see FIG. 2A ), which will be described later. The underlayer film 310 is a film onto which an opening pattern of the photoresist film 320 is transferred in an etching process (see S107), which will be described later. The underlayer film 310 may be, for example, a silicon-containing film (e.g., a spin-on-glass (SOG) film) or a carbon-containing film (e.g., a spin-on-carbon (SOC) film). The underlayer film 310 may also be a laminated film in which multiple films, such as silicon-containing films and carbon-containing films, are stacked. The underlayer film 310 as a laminated film may also include a film such as a bottom anti-reflective coating (BARC). The underlayer film 310 may also be a film used as, for example, a hard mask.

[0011] In step S102, the substrate is subjected to a process of forming a photoresist film 320. Fig. 2A is an example of a schematic cross-sectional view of the substrate after the photoresist film 320 has been formed.

[0012] Here, a photoresist film 320 is formed on an underlayer film 310. The photoresist film 320 is a film containing a metal oxide containing a first metal element. The photoresist film 320 may be a metal oxide resist containing the first metal element, or a resin resist (chemically amplified resist (CAR)) using a metal oxide containing the first metal element as a sensitizer, but is not limited thereto. Here, the first metal element includes one or more of Sn, W, Te, Zn, Zr, Sb, In, etc. The metal oxide may be, for example, SnO ｘ (x is any number), WO ｘ (x is an arbitrary number), TeO ｘ(x is an arbitrary number), ZnO ｘ (x is an arbitrary number), ZrO ｘ (x is an arbitrary number), SbO ｘ (x is an arbitrary number), InO ｘ (x is any number), etc. Furthermore, the valence of the first metal element in the photoresist film 320 changes when the photoresist film 320 is exposed to EUV (Extreme Ultraviolet) in an exposure process (see S103) described below. Furthermore, the photoresist film 320 is a negative photoresist film.

[0013] In step S103, the substrate is subjected to an exposure process. Fig. 2B is an example of a schematic cross-sectional view of the substrate after the exposure process.

[0014] Here, in a nitrogen atmosphere, EUV is irradiated onto the photoresist film 320 of the substrate through a photomask (not shown) having a predetermined pattern, thereby forming exposed portions 321 irradiated with EUV and unexposed portions 322 not irradiated with EUV in the photoresist film 320, as shown in FIG.

[0015] In step S104, the substrate is subjected to a development process. Fig. 2C is an example of a schematic cross-sectional view of the substrate after the development process.

[0016] Here, the unexposed portions 322 of the photoresist film 320 are selectively removed by a development process. The development process can be performed using at least one of a wet process and a dry process. As a result, as shown in FIG. 2C, the photoresist film 320 (see FIG. 2A) becomes a photoresist film 320A having an opening pattern 325. Here, the width of the photoresist film 320A is shorter than the width of the exposed portions 321 (see the dashed line in FIG. 2C).

[0017] In step S105, the substrate is subjected to an annealing treatment. Here, unwanted materials adhering to the sidewalls of the photoresist film 320 are removed by the annealing treatment. The annealing temperature is set within a temperature range that does not change the catalytic function of the modified layer 321b1 (see FIG. 5C), which will be described later. In other words, the annealing temperature is set within a temperature range that does not change the valence of the first metal element in the modified layer 321b1 (see FIG. 5C), which will be described later. The annealing temperature is, for example, within a range of 60°C to 250°C. The annealing treatment is not essential and may be omitted.

[0018] In step S106, a process is performed to selectively form a metal oxide film 330 on the sidewalls of the photoresist film 320. FIG. 2D is an example of a schematic cross-sectional view of the substrate after the metal oxide film 330 has been formed. The process of selectively forming the metal oxide film 330 will be described later with reference to FIGS. 3, 4, and 5A to 5C. This allows the width of the photoresist film 320A to approach a desired width (for example, the width of the exposed portion 321 irradiated with EUV shown in FIG. 2B).

[0019] In step S107, the substrate is etched. Here, the photoresist film 320 is used as a mask to etch the base film 310 using an etching gas. For example, if the base film 310 is an SOG film, a CF-based gas or the like is used as the etching gas. As a result, the opening pattern 325 of the photoresist film 320 is transferred to the base film 310, forming an opening pattern in the base film 310.

[0020] Next, the process shown in step S106 will be described with reference to FIGS. 3, 4, and 5A to 5C.

[0021] First, an example of a substrate processing apparatus that performs the processing shown in step S106 on a substrate W will be described with reference to Fig. 3. Fig. 3 is a schematic view showing an example of the substrate processing apparatus.

[0022] The substrate processing apparatus includes a processing chamber 1 , a mounting table 2 , a shower head 3 , an exhaust unit 4 , a gas supply unit 5 , and a control unit 6 .

[0023] The processing vessel 1 is made of a metal such as aluminum and has a generally cylindrical shape. The processing vessel 1 accommodates a substrate W. A loading / unloading port 11 is formed in a sidewall of the processing vessel 1 for loading and unloading the substrate W. The loading / unloading port 11 is opened and closed by a gate valve 12. An annular exhaust duct 13 having a rectangular cross section is provided on the main body of the processing vessel 1. A slit 13a is formed along the inner peripheral surface of the exhaust duct 13. An exhaust port 13b is formed in the outer wall of the exhaust duct 13. A ceiling wall 14 is provided on the upper surface of the exhaust duct 13 to close the upper opening of the processing vessel 1. A seal ring 15 hermetically seals the space between the exhaust duct 13 and the ceiling wall 14.

[0024] The mounting table 2 horizontally supports the substrate W within the processing chamber 1. The mounting table 2 has a disk shape larger than the substrate W and is made of a ceramic material such as aluminum nitride (AlN) or a metal material such as an aluminum or nickel alloy. A heater 21 for heating the substrate W is embedded inside the mounting table 2. The heater 21 generates heat when power is supplied from a heater power supply (not shown). The output of the heater 21 is controlled by a temperature signal from a thermocouple (not shown) provided near the top surface of the mounting table 2, thereby controlling the substrate W to a predetermined temperature. A cover member 22 made of ceramic such as alumina is provided on the mounting table 2 to cover the outer periphery of the top surface and the side surfaces.

[0025] The mounting table 2 is supported by a support member 23. The support member 23 extends from the center of the bottom surface of the mounting table 2 to below the processing vessel 1, passing through a hole formed in the bottom wall of the processing vessel 1, and its lower end is connected to a lifting mechanism 24. The lifting mechanism 24 moves the mounting table 2 up and down between a processing position indicated by a solid line in FIG. 3 and a transfer position indicated by a two-dot chain line below that where a substrate W can be transferred. A flange 25 is attached to the support member 23 below the processing vessel 1. A bellows 26 is provided between the bottom surface of the processing vessel 1 and the flange 25. The bellows 26 separates the atmosphere inside the processing vessel 1 from the outside air and expands and contracts as the mounting table 2 is raised and lowered.

[0026] Three wafer support pins 27 (only two are shown) are provided near the bottom of the processing vessel 1 so as to protrude upward from a lift plate 27a. The wafer support pins 27 are raised and lowered via the lift plate 27a by a lift mechanism 28 provided below the processing vessel 1. The wafer support pins 27 are inserted into through holes 2a provided in the mounting table 2 at the transfer position, and are capable of protruding and retracting from the upper surface of the mounting table 2. By raising and lowering the wafer support pins 27, the substrate W is transferred between a transfer robot (not shown) and the mounting table 2.

[0027] The showerhead 3 supplies a processing gas into the processing chamber 1 in a shower-like manner. The showerhead 3 is made of, for example, a metal material and is disposed facing the mounting table 2. The showerhead 3 has approximately the same diameter as the mounting table 2. The showerhead 3 includes a main body 31 and a shower plate 32. The main body 31 is fixed to the lower surface of the ceiling wall 14. The shower plate 32 is connected below the main body 31. A gas diffusion space 33 is formed between the main body 31 and the shower plate 32. A gas introduction hole 36 is provided in the gas diffusion space 33 so as to penetrate through the center of the ceiling wall 14 and the main body 31. A downwardly protruding annular protrusion 34 is formed on the periphery of the shower plate 32. A number of gas discharge holes 35 are formed on the flat surface of the shower plate 32 on the inner side of the annular protrusion 34.

[0028] When the mounting table 2 is in the processing position, a processing space 38 is formed between the mounting table 2 and the shower plate 32, and the upper surface of the cover member 22 and the annular protrusion 34 are close to each other to form an annular gap 39.

[0029] The exhaust unit 4 exhausts the inside of the processing vessel 1. The exhaust unit 4 includes an exhaust pipe 41 and an exhaust mechanism 42. The exhaust pipe 41 is connected to the exhaust port 13b. The exhaust mechanism 42 is connected to the exhaust pipe 41 and includes a vacuum pump, a pressure control valve, etc. The exhaust mechanism 42 exhausts gases inside the processing vessel 1 via the exhaust duct 13 and the exhaust pipe 41.

[0030] The gas supply unit 5 supplies various gases to the shower head 3. The gas supply unit 5 has a gas supply source 51. The gas supply source 51 supplies various processing gases from the gas outlet holes 35 through the gas introduction holes 36 and the gas diffusion space 33 to the processing space 38.

[0031] The control unit 6 is, for example, a computer, and includes a CPU (Central Processing Unit), RAM (Random Access Memory), ROM (Read Only Memory), an auxiliary storage device, etc. The CPU operates based on a program stored in the ROM or the auxiliary storage device, and controls the operation of the substrate processing apparatus. The control unit 6 may be provided inside or outside the substrate processing apparatus. When the control unit 6 is provided outside the substrate processing apparatus, the control unit 6 can control the substrate processing apparatus via a communication network, such as a wired or wireless communication network.

[0032] Next, an example of a film formation process in the substrate processing apparatus will be described with reference to Fig. 4. Fig. 4 is a flowchart showing an example of a film formation process in the substrate processing apparatus.

[0033] In step S201, a substrate is prepared. Here, the substrate to be prepared has an undercoat film 310 and a photoresist film 320A formed on the undercoat film 310 and having an opening pattern 325, as shown in FIG. 2C.

[0034] Here, the substrate to be prepared will be described using Figures 5A to 5C, with reference to Figures 1 and 2. Figures 5A to 5C are examples of schematic cross-sectional views of a photoresist film 320.

[0035] FIG. 5A is an example of a schematic cross-sectional view of photoresist film 320A formed in step S102.

[0036] 5B is an example of a schematic cross-sectional view of the photoresist film 320 after the exposure process (S103). Here, in the exposure process of step S103, the EUV photon dose is smaller than the photon dose that would cause the entire exposed portion 321 to react. As a result, a reactive layer 321a is formed in the center of the exposed portion 321, and a modified layer 321b is formed on the outer periphery of the exposed portion 321. The reactive layer 321a is a region that has been sufficiently exposed to EUV and has changed the valence of the first metal element due to the EUV. The modified layer 321b is a region that has not been sufficiently exposed to EUV, and in which the first metal element remains in part, with its valence unchanged.

[0037] 5C is an example of a cross-sectional schematic diagram of the photoresist film 320A after the development process (S104). The development process removes the unexposed portion 322 and a portion of the denatured layer 321b. This results in the formation of the photoresist film 320A having a denatured layer 321b1 on the sidewall. In this case, the denatured layer 321b1 contains the first metal element whose valence has not changed.

[0038] 4 , in step S202, a metal-containing gas containing a second metal element different from the first metal element is supplied to the substrate as a precursor gas (film formation gas). Here, the control unit 6 controls the gas supply unit 5 to supply the metal-containing gas containing the second metal element into the processing chamber 1. The second metal element includes one or more of Al, Ti, Ga, Ru, Hf, and Sn, W, Te, Zn, Zr, Sb, In, etc., only if they are not used as the first metal element. In other words, when any of "Sn, W, Te, Zn, Zr, Sb, In" is selected as the first metal element, the second metal element may be any of "Al, Ti, Ga, Ru, Hf" and "Sn, W, Te, Zn, Zr, Sb, In," excluding the element selected as the first metal element. Examples of the metal-containing gas containing the second metal element include TMA (trimethylaluminum), TDMAT (tetrakis(dimethylamino)titanium), TEGa (triethylgallium), and Ru. ３ CO １２Furthermore, by setting the temperature to be lower than the temperature at which the metal-containing gas forms a film by thermal decomposition, formation of the metal oxide film 330 on the top surface of the photoresist film 320 and at the bottom of the opening in the photoresist film 320 is suppressed.

[0039] In contrast, in the modified layer 321b on the side wall of the photoresist film 320A, the first metal element remaining in the modified layer 321b1, whose valence has not changed, acts as a catalyst to react with a metal-containing gas containing a second metal element, thereby decomposing the precursor of the metal-containing gas and selectively forming a metal oxide film (metal-containing film) 330 on the side wall of the photoresist film 320A.

[0040] In step S203, an inert gas is supplied to the substrate. The control unit 6 controls the gas supply unit 5 to supply the inert gas into the processing chamber 1. The inert gas is a gas that is inert to the sidewall of the photoresist film 320A and the metal-containing gas. The inert gas is nitrogen (N ２ The inert gas includes at least one of Ar gas, Ar gas, He gas, etc. Here, the metal-containing gas physically adsorbed on the upper surface of the photoresist film 320, the bottom of the opening in the photoresist film 320 (portions exposed from the opening in the base film 310), etc. is purged with the inert gas.

[0041] In step S204, the control unit 6 determines whether the processes of steps S202 and S203 have been repeated a predetermined number of times. If the processes have not been repeated the predetermined number of times (S204: NO), the control unit 6 returns to step S202 and repeats the process. Here, when the thickness of the metal oxide film 330 reaches a predetermined thickness (e.g., approximately 1 nm), the catalytic effect of the denatured layer 321b1 disappears, and the growth of the metal oxide film 330 stops. This allows the thickness of the metal oxide film 330 to be suitably controlled. Then, if the processes have been repeated the predetermined number of times (S204: YES), the control unit 6 ends the process.

[0042] In step S202, a metal-containing gas containing a second metal element is supplied as a precursor gas (film-forming gas) to form a metal oxide film 330 containing the second metal element on the sidewall of the photoresist film 320A. However, this is not limited to this. Alternatively, instead of the metal-containing gas, a semiconductor gas containing one or more semiconductor raw materials (semiconductor elements) of Si, B, Ge, Se, etc. may be supplied into the processing chamber 1 as the precursor gas (film-forming gas) to form a semiconductor film (not shown) containing a semiconductor raw material (semiconductor element) different from the first metal element on the sidewall of the photoresist film 320A. That is, in step S202, either a metal-containing gas containing the second metal element or a semiconductor gas containing a semiconductor raw material may be supplied. This may result in selective deposition of a semiconductor film (not shown) containing a semiconductor raw material (semiconductor element) on the sidewall of the photoresist film 320A. Furthermore, this is not limited to this. In step S202, both a metal-containing gas containing the second metal element and a semiconductor gas containing a semiconductor raw material may be supplied.

[0043] Thus, if the exposure process uses a lower dose of photons than the desired dose required to react the entire exposed portion 321, the pattern formed in the photoresist film 320A will be narrower than the desired width (see FIGS. 2C and 5C ). In contrast, the substrate processing method shown in FIGS. 1 and 4 allows the photoresist film 320A to be formed with the desired width by selectively depositing a metal oxide film 330 on the sidewalls of the photoresist film 320A. This improves the shape of the opening pattern transferred to the base film 310 during the etching process.

[0044] In other words, the dose of photons in the exposure process can be reduced, the power consumption in the exposure process can be reduced, and the exposure process time can be reduced, thereby improving throughput.

[0045] Alternatively, the thickness of the denatured layer 321b1 and the amount of the first metal element whose valence has not changed remaining in the denatured layer 321b1 may be adjusted to adjust the film thickness of the metal oxide film 330. Specifically, the thickness of the denatured layer 321b1 and the amount of the first metal element whose valence has not changed remaining in the denatured layer 321b1 are adjusted by adjusting the photon dose and exposure time in the exposure process, the development time in the development process, and the like.

[0046] 3 has been described as an apparatus that performs the selective film formation process (S106), but is not limited to this. In addition to the selective film formation process (S106), the substrate processing apparatus shown in FIG. 3 may be configured to perform one or more of the development process (S104), the annealing process (S105), and the etching process (S107).

[0047] In addition, the device that performs the development process (S104), the device that performs the annealing process (S105), the device that performs the selective film formation process (S106), and the device that performs the etching process (S107) may each be composed of separate devices, and the substrate processing apparatus may be configured such that these devices are connected by the same transport device.

[0048] The substrate processing method according to the present embodiment has been described above, but the present disclosure is not limited to the above embodiment, and various modifications and improvements are possible within the scope of the gist of the present disclosure as set forth in the claims.

[0049] This application claims priority based on Japanese Patent Application No. 2023-141102, filed on August 31, 2023, the entire contents of which are incorporated herein by reference.

[0050] 310 Undercoat film 320, 320A Photoresist film 321 Exposed portion 321a Reaction layer 321b, 321b1 Modified layer 322 Unexposed portion 330 Metal oxide film

Claims

1. A substrate processing method comprising the steps of: preparing a substrate having a photoresist film containing a metal oxide containing a first metal element; subjecting the substrate to exposure and development processes to form an opening pattern in the photoresist film; and supplying a metal-containing gas containing a second metal element different from the first metal element to the substrate to form a metal oxide film containing the second metal element on a side wall of the photoresist film.

2. The substrate processing method of claim 1, wherein the exposure process involves exposing to extreme ultraviolet light to form exposed and unexposed areas in the photoresist film, and the exposed areas have a reaction layer which is an area where the valence of the first metal element has been changed by the extreme ultraviolet light, and a denatured layer which is an area where the first metal element whose valence has not changed remains.

3. The substrate processing method according to claim 2, wherein the developing treatment removes the unexposed area and a part of the denatured layer.

4. The substrate processing method according to claim 3, wherein the step of forming the metal oxide film comprises forming the metal oxide film containing the second metal element on a side wall of the photoresist film using the first metal element whose valence in the modified layer has not changed as a catalyst.

5. The substrate processing method according to claim 4, further comprising adjusting a thickness of the metal oxide film based on a thickness of the modified layer and an amount of the first metal element remaining in the modified layer whose valence has not changed.

6. The substrate processing method according to claim 1, further comprising the step of performing an annealing treatment on the substrate within a temperature range in which the valence of the first metal element does not change, after the step of forming the opening pattern in the photoresist film and before the step of forming the metal oxide film.

7. The substrate processing method according to claim 1, further comprising the step of supplying an inert gas to the substrate after the step of forming the metal oxide film.

8. The substrate processing method according to claim 1, wherein the first metal element includes any one of Sn, W, Te, Zn, Zr, Sb, and In.

9. The substrate processing method according to claim 1, wherein the second metal element includes any one of Al, Ti, Ga, Ru, Hf, and Sn, W, Te, Zn, Zr, Sb, and In only when not used as the first metal element.

10. The substrate processing method according to claim 1, further comprising the step of supplying a semiconductor gas containing a semiconductor material to the substrate to form a semiconductor film containing the semiconductor material different from the first metal element on a side wall of the photoresist film, instead of the step of forming a metal oxide film containing the second metal element.

11. The substrate processing method according to claim 10, wherein the semiconductor raw material contains any one of Si, B, Ge, and Se.

12. A substrate processing apparatus comprising: a mounting table supporting a substrate having a photoresist film having an opening pattern formed thereon, the photoresist film including a metal oxide containing a first metal element; a processing vessel accommodating the mounting table; a gas supply unit supplying gas into the processing vessel; and a control unit, wherein the control unit is configured to be capable of supplying a metal-containing gas including a second metal element different from the first metal element into the processing vessel, and forming a metal oxide film including the second metal element on a side wall of the photoresist film.

13. The substrate processing apparatus according to claim 12, wherein the control unit is configured to be able to execute a process of supplying an inert gas into the processing vessel.

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