Substrate processing method, structure, and film formation device

Abstract

A substrate processing method according to the present invention is performed by a film formation device in a processing container, and comprises a step (a) and a step (b). The step (a) is for providing a glass substrate that has a first surface on which an optical element is formed and a second surface which is opposite to the first surface. The step (b) is for forming silicon-containing films, which each contain nitrogen, simultaneously on the first surface and the second surface of the glass substrate, wherein the nitrogen addition amount is controlled so that the silicon-containing film formed on the first surface has a refractive index with which the silicon-containing film functions as an optical element, and the silicon-containing film formed on the second surface has a refractive index with which a sensor disposed in a device used in processes subsequent to the step (b) can detect the glass substrate.

Description

Substrate processing method, structure, and film forming apparatus

[0001] The present disclosure relates to a substrate processing method, a structure, and a film forming apparatus.

[0002] For example, Patent Document 1 discloses that "When a plurality of cut thin glass substrates are combined to be used as a light guide plate, the cut thin glass substrates are typically stacked and used as the light guide plate. The light guide is applied to display devices such as head-mounted displays, for example."

[0003] Japanese Patent Application Laid-Open No. 2022-36174

[0004] The present disclosure provides a substrate processing method, a structure, and a film forming apparatus capable of processing a glass substrate on which optical elements are formed.

[0005] One aspect of the present disclosure is a substrate processing method performed by a film formation apparatus in a processing chamber, the method including steps (a) and (b). Step (a) provides a glass substrate having a first surface on which an optical element is formed and a second surface opposite the first surface. Step (b) simultaneously forms nitrogen-doped silicon-containing films on the first and second surfaces of the glass substrate, controlling the amount of nitrogen doping so that the silicon-containing film formed on the first surface has a refractive index that allows it to function as an optical element, and the silicon-containing film formed on the second surface has a refractive index that allows the glass substrate to be detected by a sensor disposed in an apparatus used in a process subsequent to step (b).

[0006] According to the present disclosure, it is possible to provide a substrate processing method, a structure, and a film forming apparatus capable of processing a glass substrate on which optical elements are formed.

[0007] FIG. 1 is a schematic diagram of a substrate processing system according to an embodiment. FIG. 2 is a schematic cross-sectional view of a film forming apparatus according to an embodiment. FIG. 3 is a flowchart showing an example of a film forming method in a substrate processing method according to an embodiment. FIG. 4A is a schematic cross-sectional view of a glass substrate before processing. FIG. 4B is a schematic cross-sectional view of a glass substrate after processing. FIG. 5 is a flowchart showing an example of a pattern forming method in a substrate processing method according to an embodiment. FIG. 6A is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6B is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6C is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6D is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6E is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6F is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6G is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6H is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6I is a schematic cross-sectional view of a structure in a pattern formation process. FIG. 6J is a schematic cross-sectional view of the structure during a patterning process. FIG. 7 is a graph showing an example of the refractive index of a nitrogen-doped amorphous silicon film. FIG. 8A is a schematic cross-sectional view of a metalens having the structure. FIG. 8B is a schematic cross-sectional view of a unit cell of the metalens. FIG. 8C is a schematic plan view of a unit cell of the metalens.

[0008] The following describes in detail embodiments of the disclosed substrate processing method, structure, and film forming apparatus with reference to the drawings. Note that the substrate processing method, structure, and film forming apparatus according to the present disclosure are not limited to these embodiments, and the following embodiments can be appropriately combined within the scope of the present disclosure, so long as they do not cause any contradiction between the configurations and processing contents.

[0009] Furthermore, in the following embodiments, expressions such as "constant," "orthogonal," "perpendicular," or "parallel" may be used, but these expressions do not necessarily mean "constant," "orthogonal," "perpendicular," or "parallel" in the strict sense. In other words, the above expressions allow for deviations due to, for example, manufacturing precision, installation precision, etc.

[0010] The drawings referred to below are schematic for the sake of convenience. Therefore, details may be omitted, and the dimensional ratios do not necessarily correspond to the actual ones. In addition, in the drawings referred to below, the vertically upward direction is defined as the Z-axis direction for ease of understanding.

[0011] [Glass Substrate] There is a process for manufacturing a structure by performing processes such as etching and film formation on a glass substrate. In this glass substrate processing process, at least one of the following problems may occur: metal contamination occurs inside the substrate processing apparatus; it becomes difficult to transport the glass substrate; and it becomes difficult to electrostatically hold the glass substrate to the substrate mounting surface. As a result, it may be impossible to perform processes such as etching and film formation on the glass substrate.

[0012] For example, metals such as sodium and calcium may adhere to the surface of a glass substrate, which may contaminate the inside of a substrate processing apparatus and cause defects in structures fabricated in the substrate processing apparatus.

[0013] Furthermore, for example, a substrate processing apparatus may have a sensor having a light-emitting element and a light-receiving element at a substrate transport entrance or the like, and detect the position of the substrate based on whether light emitted from the light-emitting element is blocked before reaching the light-receiving element. The substrate processing apparatus then transfers the substrate to and from a transport device based on the detection result. However, glass substrates transmit light and do not block it. Therefore, the substrate processing apparatus cannot detect the position of transparent glass substrates, and therefore cannot automatically transport glass substrates.

[0014] Furthermore, for example, in a substrate processing apparatus, during substrate processing, the substrate is electrostatically attracted to the substrate mounting surface by an electrostatic chuck mounted on each substrate mounting portion of a substrate holder. However, if a glass substrate is an insulator, the substrate processing apparatus cannot hold each substrate by the electrostatic chuck.

[0015] Therefore, the present disclosure provides a substrate processing method, a structure, and a film formation apparatus that can suppress or prevent at least one of the above problems and perform processes such as etching and film formation on a glass substrate. The present disclosure also provides a method for controlling the refractive index of a silicon-containing film formed on a glass substrate by controlling the amount of nitrogen added to the silicon-containing film. A nitrogen-added silicon-containing film is a film containing silicon as a main component and to which nitrogen is added. The main component is, for example, the atom that is most abundant in a molecular formula.

[0016] In this specification, as an example of a nitrogen-doped silicon-containing film, an example will be described in which a nitrogen-doped amorphous silicon film (hereinafter referred to as a nitrogen-doped amorphous silicon film) is formed and a pattern is formed on the formed nitrogen-doped amorphous silicon film. However, the nitrogen-doped silicon-containing film is not limited to a nitrogen-doped amorphous silicon film. The nitrogen-doped silicon-containing film may be a film obtained by adding nitrogen to any of an amorphous silicon film, a polysilicon film, or a silicon film doped with at least one of phosphorus, boron, arsenic, antimony, aluminum, or gallium. In other words, the nitrogen-doped silicon film may be a film obtained by adding nitrogen to any of a crystalline silicon film, an amorphous silicon film, or a crystalline and / or amorphous silicon film doped with at least one of phosphorus, boron, arsenic, antimony, aluminum, or gallium. Furthermore, when controlling the amount of nitrogen added to the silicon-containing film to be formed in order to control the refractive index of the silicon-containing film, the amount of nitrogen added to the silicon-containing film may be controlled to zero. By such control, the formed silicon-containing film becomes an amorphous silicon film without nitrogen addition.

[0017] [Substrate Processing System] A substrate processing system according to an embodiment of the present disclosure will be described with reference to Fig. 1. Fig. 1 is a schematic diagram of a substrate processing system 1 according to an embodiment. The substrate processing system 1 includes a control device 2, a film forming device 3, an etching device 4, and a processing device group 5. The film forming device 3, the etching device 4, and the processing device group 5 are controlled by the control device 2. The film forming device 3, the etching device 4, and the processing device group 5 are examples of substrate processing devices.

[0018] The film forming device 3 forms a nitrogen-doped amorphous silicon film on the glass substrate. The etching device 4 removes the amorphous silicon film from the rear surface of the glass substrate. The processing device group 5 has a plurality of processing devices that perform processes such as cleaning on the glass substrate. The processing device group 5 may include a vacuum transfer chamber, a plurality of processing devices, a plurality of load lock chambers, and an atmospheric transfer chamber.

[0019] The control device 2 has a memory, a processor, and an input / output interface. Data such as recipes and programs are stored in the memory. The memory may be, for example, a random access memory (RAM), a read-only memory (ROM), a hard disk drive (HDD), or a solid state drive (SSD). The processor may be a central processing unit (CPU) or a digital signal processor (DSP). The processor executes a program read from the memory to control each component of the film forming device 3, the etching device 4, and the processing device group 5 via the input / output interface based on data such as recipes stored in the memory.

[0020] [Film Forming Apparatus] Next, a film forming apparatus will be described with reference to FIG. 2. FIG. 2 is a schematic cross-sectional view of a film forming apparatus 3 according to one embodiment. FIG. 2 shows, as an example of the film forming apparatus 3, a batch-type heat treatment apparatus that performs heat treatment on multiple substrates at once. Note that the film forming apparatus 3 may also be a single-wafer type film forming apparatus that performs heat treatment on, for example, one or several substrates. The film forming apparatus 3 forms a nitrogen-doped amorphous silicon film on, for example, a glass substrate.

[0021] The film forming apparatus 3 has a processing vessel 32. The processing vessel 32 has an inner tube 33 and an outer tube 34. The inner tube 33 has a cylindrical shape with an open bottom and top end. The outer tube 34 has a cylindrical shape with an open bottom end and a ceiling that covers the outside of the inner tube 33. The inner tube 33 and the outer tube 34 are arranged coaxially to form a double-tube structure. The inner tube 33 and the outer tube 34 are made of, for example, quartz.

[0022] The lower end of the outer pipe 34 is supported by a cylindrical manifold 35 made of, for example, stainless steel. A support ring 36 protrudes inward from the inner wall of the manifold 35 and is formed integrally with the manifold 35. The lower end of the inner pipe 33 is supported by the support ring 36.

[0023] A lid 37 is disposed below the manifold 35. A substrate holder 39 made of, for example, quartz is disposed on the lid 37. A plurality of glass substrates 10 are accommodated in the substrate holder 39 at predetermined intervals in the vertical direction. The lid 37 is configured to be moved up and down by a boat elevator 38. When the boat elevator 38 raises the lid 37, the substrate holder 39 holding the plurality of glass substrates 10 is loaded into the processing vessel 32, and the lower side (throat portion) of the manifold 35 is closed. When the boat elevator 38 lowers the lid 37, the lower side (throat portion) of the manifold 35 is opened, and the substrate holder 39 is unloaded from the processing vessel 32.

[0024] A heat insulator 310 is provided around the processing vessel 32 so as to surround the processing vessel 32. A heater 311, such as a resistance heating element, is provided on the inner wall surface of the heat insulator 310. The heater 311 heats the inside of the processing vessel 32 to a predetermined temperature. As a result, the glass substrate 10 placed in the processing vessel 32 is heated to the predetermined temperature.

[0025] Gas introduction pipes 312 and 313 for introducing a plurality of process gases are connected to the side of the manifold 35. Specifically, the gas introduction pipes 312 and 313 are connected to the side of the manifold 35 below the inner pipe 33 and below the support ring 36. The gas introduction pipe 312 supplies a silicon-containing gas to the space within the process vessel 32. The gas introduction pipe 313 supplies a nitrogen-containing gas to the space within the process vessel 32. Although two gas introduction pipes 312 and 313 are provided in the illustrated example, a single gas introduction pipe may be provided. In this case, a silicon-containing gas and a nitrogen-containing gas are supplied from one gas introduction pipe. The number of gas introduction pipes provided may depend on the type of process gas. The silicon-containing gas may be, for example, monosilane gas (SiH ４ ), disilane gas (Si ２ H ６ ), trisilane gas (Si ３ H ８ ), tetrasilane gas (Si ４ H １０ ), dichlorosilane gas (SiH ２ Cl ２ : DCS), hexachlorodisilane gas (Si ２ Cl ６ ), tetrachlorosilane gas (SiCl ４ ), trichlorosilane gas (SiHCl ３ The nitrogen-containing gas may include, for example, ammonia gas (NH ３ ), nitric oxide gas (NO) or nitrogen dioxide gas (N ２ O). Note that, for example, in forming an amorphous silicon film, these gases are not converted into plasma.

[0026] The control device 2 controls the nitrogen content (addition amount) in the nitrogen-doped amorphous silicon film by controlling the flow rate of the nitrogen-containing gas relative to the total flow rate of the silicon-containing gas and the nitrogen-containing gas, thereby adjusting the refractive index of the amorphous silicon film.

[0027] The gas inlet pipe 313 is connected to a process gas supply source (not shown) via a mass flow controller (not shown) etc. The process gas supply source supplies a silicon-containing gas and a nitrogen-containing gas at predetermined flow rates into the space within the inner pipe 33 via the gas inlet pipes 312 and 313.

[0028] An exhaust port 314 for exhausting gas from the space within the processing vessel 32 is provided on the side of the manifold 35. The exhaust port 314 is provided above the support ring 36 and communicates with the space formed between the inner tube 33 and the outer tube 34 within the processing vessel 32. An exhaust pipe 316 is airtightly connected to the exhaust port 314. A valve 317 and a vacuum pump 318 are provided on the exhaust pipe 316. The valve 317 adjusts the opening of the exhaust pipe 316 to control the pressure within the processing vessel 32 to a predetermined pressure. The vacuum pump 318 exhausts gas from the processing vessel 32 via the exhaust pipe 316.

[0029] A purge gas supply pipe 315 for supplying a purge gas may be inserted below the exhaust port 314 on the side surface of the manifold 35. A purge gas supply source (not shown) may be connected to the purge gas supply pipe 315. The purge gas supply source may supply a purge gas at a predetermined flow rate into the processing vessel 32 via the purge gas supply pipe 315. The purge gas may be an inert gas such as argon gas. A sensor 319 for detecting the position of the glass substrate 10 is arranged in the manifold 35.

[0030] [Substrate Processing Method] Next, an example of a film formation method in a substrate processing method according to an embodiment will be described with reference to Figures 3, 4A, and 4B. Figure 3 is a flowchart showing an example of a film formation method in a substrate processing method according to an embodiment. Figure 4A is a schematic cross-sectional view of a glass substrate 10 before processing. Figure 4B is a schematic cross-sectional view of the glass substrate 10 after processing. The substrate processing method according to an embodiment is performed by a film formation apparatus 3. Each component of the film formation apparatus 3 is controlled by a control device 2. An example of a film formation method for forming a nitrogen-containing amorphous silicon film will be described below.

[0031] <Film Formation Method> (Loading Step) First, in step S101, the control device 2 executes the loading step. Specifically, the control device 2 controls the temperature inside the processing vessel 32 to, for example, 300°C using the heater 311, and then lowers the lid 37 using the boat elevator 38, and places the substrate holder 39, which houses multiple glass substrates 10, on the lid 37. However, the controlled temperature is not limited to 300°C. The control device 2 supplies a predetermined amount of purge gas into the processing vessel 32 from the purge gas supply pipe 315, raises the lid 37 using the boat elevator 38, and loads the substrate holder 39 into the processing vessel 32. This seals the processing vessel 32 with the glass substrates 10 housed in the inner tube 33 of the processing vessel 32. The loading step in step S101 is an example of a process (a) of providing glass substrates 10.

[0032] (Stabilization Step) Next, in step S102, the control device 2 executes the stabilization step. Specifically, the control device 2 drives the vacuum pump 318 to exhaust gas from the processing vessel 32 while controlling the opening of the valve 317. The control device 2 exhausts gas from the processing vessel 32 until the desired pressure is reached within the processing vessel 32, achieving the target reduced pressure state. The control device 2 also uses the heater 311 to heat the interior of the processing vessel 32 to, for example, 760°C. The control device 2 then performs this decompression and heating operation until the processing vessel 32 stabilizes at the predetermined pressure and temperature. However, the stabilization temperature is not limited to 760°C.

[0033] (Gas Supply Process) Next, in step S103, the control device 2 executes the gas supply process. Specifically, the control device 2 stops the supply of purge gas from the purge gas supply pipe 315. Then, the control device 2 introduces monosilane gas at a predetermined flow rate from the gas inlet pipe 312 and introduces ammonia gas at a predetermined flow rate from the gas inlet pipe 313.

[0034] The deposition conditions for the nitrogen-doped amorphous silicon film are as follows: Deposition condition 1 Gas species: monosilane gas, ammonia gas Deposition condition 2 Gas species: disilane gas, ammonia gas Deposition condition 3 Gas species: monosilane gas, nitric oxide gas Deposition condition 4 Gas species: monosilane gas, nitrogen dioxide gas In order to control the refractive index of the silicon-containing film, the amount of nitrogen added to the silicon-containing film to be deposited may be controlled by selecting an appropriate aminosilane gas.

[0035] (Nitrogen-Doped Amorphous Silicon Film Forming Process) Next, in step S104, the control device 2 executes the nitrogen-doped amorphous silicon film forming process. Specifically, the control device 2 thermally decomposes the introduced monosilane gas and ammonia gas by heating with the heater 311, thereby depositing a nitrogen-doped amorphous silicon film on the glass substrate 10. The control device 2 controls the amount of nitrogen added so that the nitrogen-doped amorphous silicon film formed on the first surface has a refractive index that functions as an optical element, and the nitrogen-doped amorphous silicon film formed on the second surface has a refractive index that allows a sensor disposed in an apparatus used in a process subsequent to step (b) to detect the glass substrate. As a result, a nitrogen-doped amorphous silicon film having the above refractive index is formed on the glass substrate 10. The gas supply process of step S103 and the film forming process of step S104 are an example of step (b) of forming a nitrogen-doped amorphous silicon film.

[0036] 4A shows a single glass substrate 10. The glass substrate 10 has a first surface 10a and a second surface 10b. For example, the first surface 10a is the processed surface of the glass substrate 10 and is a surface perpendicular to the Z-axis direction. The second surface 10b is the surface opposite to the first surface 10a and is also perpendicular to the Z-axis direction. Furthermore, the glass substrate 10 has a side surface 10c connecting the first surface 10a and the second surface 10b. The side surface 10c is a surface horizontal to the Z-axis direction.

[0037] As shown in FIG. 4B , nitrogen-doped amorphous silicon is simultaneously formed on the first surface 10 a, the second surface 10 b, and the side surface 10 c of the glass substrate 10. Furthermore, nitrogen-doped amorphous silicon is simultaneously formed on multiple glass substrates 10 held by the substrate holder 39. By controlling the amount of nitrogen added, the nitrogen-doped amorphous silicon formed on the first surface 10 a has a refractive index that functions as an optical element, and the nitrogen-doped amorphous silicon formed on the second surface 10 b has a refractive index that allows a sensor disposed in an apparatus used in a process subsequent to step (b) to detect the glass substrate 10. The refractive indices of the nitrogen-doped amorphous silicon on the first surface 10 a and the second surface 10 b may be the same. Thereafter, the control device 2 stops the supply of monosilane gas from the gas inlet pipe 312 and the supply of ammonia gas from the gas inlet pipe 313. Then, the control device 2 drives the vacuum pump 318 while controlling the opening of the valve 317 to exhaust the gas inside the processing container 32. The control device 2 also supplies a predetermined amount of purge gas from the purge gas supply pipe 315 to exhaust the gas inside the processing container 32 to the exhaust pipe 316. Note that in order to reliably exhaust the gas inside the processing container 32, the exhaust of the gas inside the processing container 32 and the supply of the purge gas may be repeated multiple times.

[0038] Next, in step S105, the control device 2 executes the unloading process. Specifically, the control device 2 supplies a predetermined amount of purge gas from the purge gas supply pipe 315 to restore atmospheric pressure inside the processing vessel 32, and then causes the boat elevator 38 to lower the lid 37 and unload the substrate holder 39 from the processing vessel 32.

[0039] By this film formation method, a nitrogen-doped amorphous silicon film 20 can be formed on a glass substrate 10. Commercially available glass substrates 10 may have metal elements, etc., attached to their surfaces during the manufacturing process. Therefore, if a film formation process is performed using a commercially available glass substrate 10 as is, components inside a processing vessel that come into contact with the glass substrate 10 may be contaminated with the metal elements. If the components inside the processing vessel are contaminated with the metal elements, the metal elements may be mixed in during processes such as etching and film formation on the glass substrate 10, causing defects in the manufactured structures such as optical elements.

[0040] 4B , in this embodiment, the glass substrate 10 is covered with the nitrogen-doped amorphous silicon film 20. This prevents the glass substrate 10 from being exposed, thereby suppressing or preventing contamination of components in the processing vessels of the film forming apparatus 3, the etching apparatus 4, and the processing apparatus group 5 with metal elements.

[0041] 2 disposed in the processing chamber 32 emits light toward the nitrogen-doped amorphous silicon film 20 formed on the glass substrate 10 during the loading or unloading process. The light emitted from the light-emitting unit passes through the glass substrate 10 but is blocked by the nitrogen-doped amorphous silicon film 20. As a result, the position of the glass substrate 10 can be detected by the sensor 319. This allows the control device 2 to automatically transport the glass substrate 10 based on the position of the glass substrate 10.

[0042] Furthermore, if the glass substrate 10 is an insulator, it is difficult for the film forming apparatus 3 to hold the glass substrate 10 on the substrate mounting surface by electrostatic adsorption. However, in this embodiment, the glass substrate 10 is covered with the conductive nitrogen-doped amorphous silicon film 20. Therefore, the film forming apparatus 3 can hold the glass substrate 10 on the substrate mounting surface by electrostatic adsorption.

[0043] This allows the nitrogen-doped amorphous silicon film 20 to be formed on the glass substrate 10. Furthermore, in the film forming apparatus 3, the number of film forming steps for forming the nitrogen-doped amorphous silicon film 20 is small, and the manufacturing process can be simplified.

[0044] <Pattern Forming Method> Next, with reference to FIGS. 5 and 6A to 6J, an example of a pattern forming method of a nitrogen-doped amorphous silicon film 20 in a substrate processing method according to an embodiment will be described. FIG. 5 is a flowchart illustrating an example of the pattern forming method in a substrate processing method according to an embodiment. FIGS. 6A to 6J are schematic cross-sectional views of a structure in a pattern forming step. The substrate processing method according to an embodiment is performed by one of the film forming apparatus 3, the etching apparatus 4, or an apparatus in the processing apparatus group 5. Each component of the film forming apparatus 3, the etching apparatus 4, or the processing apparatus group 5 is controlled by a control device 2. The glass substrate 10 is transported between the film forming apparatus 3, the etching apparatus 4, and each apparatus in the processing apparatus group 5 by a transport device (not shown) under the control of the control device 2. In the following, a pattern is formed in the nitrogen-doped amorphous silicon film 20 on the first surface 10a of the nitrogen-doped amorphous silicon film 20 formed on the glass substrate 10.

[0045] (Silicon Oxide Film Forming Process) First, in step S201, the control device 2 executes the silicon oxide film forming process. Specifically, the control device 2 controls the temperature inside the processing chamber 32 to a predetermined temperature, introduces a silane-containing gas as a source gas at a predetermined flow rate through the gas inlet pipe 312, and introduces an oxygen-containing gas as a reactive gas at a predetermined flow rate through the gas inlet pipe 313. The silane-containing gas may be monosilane gas or the like. The oxygen-containing gas may be oxygen gas or ozone gas, but the gas species are not limited thereto. The control device 2 reacts the source gas with the reactive gas to form a silicon oxide film. As a result, a silicon oxide film 40 is formed on the nitrogen-doped amorphous silicon film 20 on the first surface 10a of the glass substrate 10, as illustrated in FIG. 6A .

[0046] Although the method for forming a silicon oxide film using the film-forming apparatus 3, which is a batch-type heat treatment apparatus, has been exemplified, the method is not limited to this. The silicon oxide film may also be formed by a PVD (Physical Vapor Deposition) method, a CVD (Chemical Vapor Deposition) method, an ALD (Atomic Layer Deposition) method, spin coating, or the like.

[0047] (Hard Mask Formation Process) Next, in step S202, the control device 2 executes the hard mask formation process. Specifically, the control device 2 transports the glass substrate 10 to a hard mask formation device in the processing device group 5. The hard mask formation device may be a spin coating device that applies a hard mask by rotation. The control device 2 applies a hard mask formation treatment liquid to the silicon oxide film 40 by rotation, for example, through processing by a processing unit of the spin coating device. The control device 2 may also form a spin-on carbon (SOC) film and a spin-on glass (SOG) film as the hard mask by the coating device. As a result, as illustrated in FIG. 6B , a spin-on carbon film 51 and a spin-on glass film 52 are formed as the hard mask 50 on the silicon oxide film 40. The spin-on carbon film 51 is formed on the silicon oxide film 40, and the spin-on glass film 52 is formed on the spin-on carbon film 51. However, the hard mask 50 may be the spin-on carbon film 51 or the spin-on glass film 52. The control device 2 may also form a metal-containing film as the hard mask 50. Additionally, the hard mask 50 may comprise silicon oxynitride (SiON) or back surface anti-reflective coating (BARC).

[0048] (Resist Film Forming Process) Next, in step S203, the control device 2 executes the resist film forming process. Specifically, the control device 2 transports the glass substrate 10 to a resist film forming device in the processing device group 5, and forms a resist film thereon. The resist film may be a photoresist film for EUV (Extreme Ultraviolet). The resist film forming device may be any device that includes a resist film coating device, an exposure device, a heat treatment device, and a development device. The control device 2 applies a resist film forming treatment liquid to the hard mask 50 through processing by the processing unit of the resist film coating device, thereby forming a resist film coating. Next, the control device 2 exposes the resist film coating through processing by the processing unit of the exposure device.

[0049] The exposure apparatus irradiates the exposure target portion of the resist film with energy rays using a method such as immersion exposure. The energy rays may be, for example, ionizing radiation or non-ionizing radiation. Ionizing radiation is radiation with sufficient energy to ionize atoms or molecules. Ionizing radiation may be extreme ultraviolet (EUV), electron beams, ion beams, X-rays, α-rays, β-rays, γ-rays, heavy particle beams, proton beams, etc. Non-ionizing radiation is radiation with insufficient energy to ionize atoms or molecules. Non-ionizing radiation may be g-rays, i-rays, KrF excimer lasers, ArF excimer lasers, F2 excimer lasers, etc. After exposure, the control device 2 heat-treats the glass substrate 10 using a processing unit of the heat treatment device. Next, the control device 2 subjects the resist film coating to a development process and a post-development heat treatment using a processing unit of the development device. As a result, a pattern of the resist film 60 is formed, as shown in FIG. 6C .

[0050] However, the formation of the pattern on the resist film is not limited to this. For example, the control device 2 may apply nanoimprint lithography, in which a mold (mask) with an engraved pattern is pressed against the resist film coating, the resin resist film is hardened by ultraviolet light or heat treatment to form the pattern on the resist film, and the mold is then peeled off from the resist film.

[0051] (Hard Mask and Silicon Oxide Film Etching Process) Next, in step S204, the control device 2 performs an etching process for the hard mask 50 and the silicon oxide film 40. Specifically, the control device 2 transports the glass substrate 10 to the etching device 4. The control device 2 supplies a hard mask etching gas to a gas supply unit of the etching device 4, and the hard mask 50 is etched by processing by a processing unit of the etching device 4. As a result, as shown in FIG. 6D , a resist film pattern is formed on the spin-on carbon film 51 and the spin-on glass film 52 of the hard mask 50. The hard mask etching gas may be a gas containing fluorine, depending on the material of the hard mask 50.

[0052] Next, the control device 2 supplies a silicon oxide film etching gas to the gas supply unit of the etching device 4, and the silicon oxide film 40 is etched by processing in the processing unit of the etching device 4. As a result, the pattern of the hard mask 50 is formed in the silicon oxide film 40, as shown in FIG. 6E . The silicon oxide film 40 is etched until the nitrogen-doped amorphous silicon film 20 is exposed from the bottom of the opening 40 a in the silicon oxide film 40. The silicon oxide film etching gas may be a gas containing fluorine.

[0053] (Nitrogen-Doped Amorphous Silicon Film Etching Process) Next, in step S205, the control device 2 executes the nitrogen-doped amorphous silicon film 20 etching process. Specifically, the control device 2 supplies an amorphous silicon film etching gas to the gas supply unit of the etching device 4, and the nitrogen-doped amorphous silicon film 20 is etched by processing by the processing unit of the etching device 4. As a result, a pattern 20p of the nitrogen-doped amorphous silicon film 20 is formed, as shown in FIG. 6F . The pattern 20p is formed in the pattern of the silicon oxide film 40. The nitrogen-doped amorphous silicon film 20 is etched until the first surface 10a of the glass substrate 10 is exposed from the bottom of the opening 20pi in the nitrogen-doped amorphous silicon film 20. In the example of FIG. 6F , the unetched nitrogen-doped amorphous silicon film 20 remains on the side surface 10c of the glass substrate 10, but the nitrogen-doped amorphous silicon film 20 formed on the side surface 10c may be completely removed. The amorphous silicon film etching gas may be a gas containing fluorine. Note that steps S201 to S205 are an example of step (c) of forming a pattern in the silicon-containing film formed on the first surface 10a.

[0054] (Cleaning Process) Next, in step S206, the control device 2 executes the cleaning process. Specifically, the control device 2 transports the glass substrate 10, on which the pattern 20p of the nitrogen-doped amorphous silicon film 20 has been formed, to a cleaning device in the processing device group 5. The control device 2 supplies a cleaning gas to a gas supply unit of the cleaning device, and the glass substrate 10, on which the pattern 20p of the nitrogen-doped amorphous silicon film 20 has been formed, is cleaned by processing in a processing unit of the cleaning device. As a result, the pattern 20p of the nitrogen-doped amorphous silicon film 20 is cleaned, as shown in FIG. 6G . The cleaning gas may be a gas containing oxygen.

[0055] The control device 2 may clean the glass substrate 10 by wet processing. In the case of wet processing, a solution such as hydrogen fluoride may be used instead of the cleaning gas. After cleaning, the control device 2 may transport the glass substrate 10 to an ALD device in the processing device group 5, and form various thin films by processing in a processing section of the ALD device.

[0056] (Protective Film Forming Process) Next, in step S207, the control device 2 executes the protective film forming process. Specifically, the control device 2 transports the glass substrate 10 to an apparatus for forming the protective film. The apparatus for forming the protective film may be a spin coating apparatus or a film forming apparatus 3. The control device 2 supplies a protective film gas from a gas supply unit of the film forming apparatus to form the protective film on the pattern 20p of the nitrogen-doped amorphous silicon film 20. The control device 2 may form a protective film covering the pattern 20p of the nitrogen-doped amorphous silicon film 20 by processing using a processing unit of the film forming apparatus for forming the protective film. The protective film may be an insulator. As a result, a protective film 70 is formed on the pattern 20p of the nitrogen-doped amorphous silicon film 20, as shown in FIG. 6H.

[0057] (Removal Process) Next, in step S208, the control device 2 executes the removal process. Specifically, the control device 2 transports the glass substrate 10 to a removal device in the processing device group 5. The control device 2 supplies a removal gas to a gas supply unit of the removal device, and the nitrogen-doped amorphous silicon film 20 on the rear surface of the glass substrate 10 is removed by processing using a processing unit of the removal device. If the nitrogen-doped amorphous silicon film 20 remains on the side surface 10c of the glass substrate 10, the control device 2 removes the nitrogen-doped amorphous silicon film 20 from the rear surface and side surface of the glass substrate 10. As a result, the nitrogen-doped amorphous silicon film 20 on the second surface 10b and side surface 10c of the glass substrate 10 is removed, as shown in FIG. 6I. The removal gas may be the same as the amorphous silicon film etching gas used in step S205. The removal device may also be the etching device 4. The removal process of step S208 is an example of step (d) of removing a silicon-containing film formed on the second surface 10b.

[0058] Finally, the protective film 70 may be removed. In this case, the control device 2 supplies a protective film removal gas to the gas supply unit of the removal device, and the protective film 70 on the pattern 20p of the nitrogen-doped amorphous silicon film 20 is removed by processing by the processing unit of the etching device 4. As a result, a structure in which the pattern 20p of the nitrogen-doped amorphous silicon film 20 is formed on the first surface 10a of the glass substrate 10, as shown in FIG. 6J, can be formed. Note that steps S206 and S207 may be omitted.

[0059] [Effect] The refractive index of the amorphous silicon film can be adjusted by adjusting process parameters such as temperature and pressure when forming the amorphous silicon film. However, the control range of process parameters such as temperature and pressure is limited to the range of film formation conditions for the amorphous silicon film, so the control range of the refractive index of the film is narrow.

[0060] In contrast, in the case of the nitrogen-doped amorphous silicon film 20 formed by the above-described substrate processing method, the control range is not limited to the range of film formation conditions for the amorphous silicon film. Therefore, in the case of the nitrogen-doped amorphous silicon film 20, the control range of the film's refractive index is greater than when process parameters such as temperature and pressure are controlled. FIG. 7 is a graph showing an example of the refractive index of the nitrogen-doped amorphous silicon film 20. The horizontal axis of FIG. 7 represents the wavelength of electromagnetic waves in the visible and infrared regions. The vertical axis of FIG. 7 represents an example of the refractive index n of the nitrogen-doped amorphous silicon film 20. The refractive index in FIG. 7 is the refractive index n of the nitrogen-doped amorphous silicon film 20 formed by controlling the flow rate ratio of monosilane gas to ammonia gas during thermal CVD using the film formation apparatus 3. Note that "a-Si" in FIG. 7 refers to an amorphous silicon film. "N-doped a-Si" refers to the nitrogen-doped amorphous silicon film 20. The percentage (%) in parentheses indicates the nitrogen content in the nitrogen-doped amorphous silicon film after film formation.

[0061] 7, line a indicates the refractive index n at each wavelength of an amorphous silicon film that is not doped with nitrogen. Line b indicates the refractive index n at each wavelength of a nitrogen-doped amorphous silicon film 20 that contains 9.7% nitrogen. Line c indicates the refractive index n at each wavelength of a nitrogen-doped amorphous silicon film 20 that contains 11.6% nitrogen. Line d indicates the refractive index n at each wavelength of a nitrogen-doped amorphous silicon film 20 that contains 11.9% nitrogen. Line e indicates the refractive index n at each wavelength of a nitrogen-doped amorphous silicon film 20 that contains 18.0% nitrogen.

[0062] In the example of FIG. 7 , the refractive index n of the amorphous silicon film, indicated by line a, is approximately 4.0 to approximately 4.3 in the infrared light range of 750 nm to 1000 nm. In contrast, the refractive index n of the nitrogen-doped amorphous silicon film 20, indicated by lines b to e, decreases as the nitrogen content increases. This is thought to be because, as the nitrogen content increases, the characteristics of the nitrogen-doped amorphous silicon film 20 approach those of a silicon nitride film, and the refractive index of the nitrogen-doped amorphous silicon film 20 approaches that of a silicon nitride film, resulting in a decrease in refractive index. That is, the control device 2 can control the refractive index of the nitrogen-doped amorphous silicon film 20 by controlling the amount of nitrogen added. Furthermore, with this control, the control range of the refractive index is not limited to the range of the film formation conditions for the nitrogen-doped amorphous silicon film 20. Therefore, by controlling the amount of nitrogen added, the control range of the refractive index n of the nitrogen-doped amorphous silicon film 20 can be increased compared to controlling process parameters such as temperature and pressure. Therefore, according to the substrate processing method of this embodiment, the controllability of the refractive index of the nitrogen-doped amorphous silicon film 20 can be improved.

[0063] [Metalens] The structure of the glass substrate 10 on which the pattern 20p of the nitrogen-doped amorphous silicon film 20 is formed may be used as a metalens. That is, the nitrogen-doped amorphous silicon film 20 is transparent to electromagnetic wave wavelengths in the infrared light region, and the pattern 20p of the nitrogen-doped amorphous silicon film 20 can function as a metalens. However, a metalens is one example of a device using the glass substrate 10 on which the pattern 20p of the nitrogen-doped amorphous silicon film 20 is formed, and the present invention is not limited to this.

[0064] FIG. 8A is a schematic cross-sectional view of a metalens having a structure. The metalens 100 shown below is an example of a metalens for infrared light. In the example of FIG. 8A , the metalens 100 has a housing 101 and a pattern 20p of a nitrogen-doped amorphous silicon film 20 on a glass substrate 10. The glass substrate 10 is placed on a mounting portion 102 within the housing 101. This allows the glass substrate 10 and the pattern 20p of the nitrogen-doped amorphous silicon film 20 to be housed within the housing 101. The metalens 100 receives light through an opening 101a in the housing 101.

[0065] That is, infrared light is incident on the glass substrate 10 from above in the Z-axis direction. A pattern 20p of a nitrogen-doped amorphous silicon film 20 with a controlled refractive index is microfabricated on the glass substrate 10. This allows the metalens 100 to have the functions of focusing, refracting, and scattering light, similar to a lens made up of a combination of multiple concave and convex lenses, due to the pattern 20p of the planar nitrogen-doped amorphous silicon film 20.

[0066] The characteristics of the metalens 100 are determined by a combination of the design of the metalens 100 and the refractive index of the nitrogen-doped amorphous silicon film 20. For this reason, it is beneficial to control the refractive index of the nitrogen-doped amorphous silicon film 20 over as wide a range as possible. The metalens 100 is an example of an optical element formed on the first surface 10a of the glass substrate 10.

[0067] For example, when the light focusing cannot be designed as intended for the metalens 100, the characteristics of the metalens 100 can be brought closer to the designed values ​​by changing the amount of nitrogen added to the nitrogen-doped amorphous silicon film 20 to lower or raise the refractive index. In this way, the design of the metalens 100 can be made easier by changing the refractive index of the nitrogen-doped amorphous silicon film 20 by controlling the amount of nitrogen added to the nitrogen-doped amorphous silicon film 20 so that the designed characteristics of the metalens 100 can be obtained. As a result, the light focusing accuracy of the metalens 100 can be improved.

[0068] This also makes it possible to realize a lens that is thinner and lighter than conventional lenses that combine multiple concave and convex lenses. In other words, by replacing conventional lenses with metalens, it becomes possible to improve the precision, size, and weight of optical systems.

[0069] FIG. 8B , which is an enlarged view of the area within the dotted line in FIG. 8A , is a schematic cross-sectional view of a unit cell of the metalens 100. FIG. 8C is a schematic plan view of a unit cell of the metalens. The metalens 100 is a nanostructure (fine relief structure) in which unit cells C, which are the basic structure (unit lattice) shown in FIGS. 8B and 8C , are periodically arranged in a lattice pattern along the horizontal direction perpendicular to the Z-axis direction. As an example, as shown in FIG. 8C , the unit cells C are square regions when viewed from above in the Z-axis direction. One columnar (cylindrical in this embodiment) pillar is formed for each unit cell C. The pillar is erected on the first surface 10 a of the glass substrate 10 at the center of the unit cell C. The pattern 20 p of the nitrogen-doped amorphous silicon film 20 is a plurality of pillars periodically arranged in a lattice pattern.

[0070] The embodiment has been described above. As described above, the substrate processing method in the embodiment is performed by the film formation apparatus 3 in the processing chamber 32 and includes steps (a) and (b). Step (a) provides a glass substrate 10 having a first surface 10a on which an optical element is formed and a second surface 10b opposite the first surface 10a. Step (b) simultaneously forms nitrogen-doped silicon-containing films on the first surface 10a and the second surface 10b of the glass substrate 10, in which the amount of nitrogen added is controlled so that the nitrogen-doped silicon-containing film formed on the first surface 10a has a refractive index that allows it to function as an optical element, and the nitrogen-doped silicon-containing film formed on the second surface 10b has a refractive index that allows the glass substrate 10 to be detected by a sensor disposed in an apparatus used in a process subsequent to step (b).

[0071] By covering the glass substrate 10 with the nitrogen-doped silicon-containing film, it is possible to prevent scattering of metal elements adhering to the surface of the glass substrate. Furthermore, the nitrogen-doped silicon-containing film on the glass substrate 10 allows the sensor 319 to detect the position of the glass substrate 10. Furthermore, if the nitrogen-doped silicon-containing film is conductive, it is possible to attract the glass substrate 10 to an electrostatic chuck mounted on each substrate mounting portion of the substrate holding unit.

[0072] [Others] The technology disclosed in the present application is not limited to the above-described embodiment, and various modifications are possible within the scope of the gist thereof.

[0073] The nitrogen-doped silicon-containing film formed on the second surface 10b has a refractive index that allows a sensor disposed in an apparatus used in processes subsequent to step (b) to detect the glass substrate 10. The apparatus used in processes subsequent to step (b) may include an etching apparatus 4 and a processing apparatus group 5. Furthermore, the apparatus used in processes subsequent to step (b) may include a film-forming apparatus 3. For example, the position of the glass substrate 10 may be detected based on whether light emitted from the light-emitting unit of the sensor 319 is blocked by the nitrogen-doped silicon-containing film formed on the side surface 10c of the glass substrate 10, but the disclosed technology is not limited thereto. For example, the sensor 319 may be disposed at a position that allows the position of the glass substrate 10 to be detected based on whether light emitted from the light-emitting unit is blocked by the nitrogen-doped silicon-containing film on the first surface 10a or the second surface 10b.

[0074] It should be noted that the disclosed embodiments are illustrative in all respects and should not be considered limiting. Indeed, the above-described embodiments may be embodied in various forms. Furthermore, the above-described embodiments may be omitted, substituted, or modified in various forms without departing from the scope and spirit of the appended claims.

[0075] The following supplementary notes are further disclosed regarding the above-described embodiments. (Supplementary Note 1) A substrate processing method performed in a processing vessel by a film formation apparatus, comprising: (a) providing a glass substrate having a first surface on which an optical element is formed and a second surface opposite to the first surface; and (b) simultaneously forming nitrogen-doped silicon-containing films on the first and second surfaces of the glass substrate, wherein the amount of nitrogen added is controlled so that the silicon-containing film formed on the first surface has a refractive index that enables it to function as the optical element, and the silicon-containing film formed on the second surface has a refractive index that enables a sensor disposed in an apparatus used in a process subsequent to step (b) to detect the glass substrate. (Supplementary Note 2) The substrate processing method according to Supplementary Note 1, wherein in step (b), a silicon-containing gas and a nitrogen-containing gas are supplied into the processing vessel. (Supplementary Note 3) The substrate processing method according to Supplementary Note 2, wherein the silicon-containing gas includes at least one of monosilane gas, disilane gas, trisilane gas, tetrasilane gas, dichlorosilane gas, hexachlorodisilane gas, tetrachlorosilane gas, trichlorosilane gas, bis(tert-butylaminosilane) gas, and hexaethylaminodisilane gas. (Supplementary Note 4) The substrate processing method according to Supplementary Note 2 or 3, wherein the nitrogen-containing gas includes at least one of ammonia gas, nitric oxide gas, and nitrogen dioxide gas. (Supplementary Note 5) The substrate processing method according to any one of Supplements 1 to 4, comprising the step of (c) forming a pattern in the silicon-containing film deposited on the first surface. (Supplementary Note 6) The substrate processing method according to Supplementary Note 5, comprising the step of (d) removing the silicon-containing film deposited on the second surface after the step (c). (Supplementary Note 7) The substrate processing method according to Supplementary Note 2 or 3, wherein the refractive index of the silicon-containing film is adjusted by controlling a flow rate of the nitrogen-containing gas relative to a total flow rate of the silicon-containing gas and the nitrogen-containing gas. (Supplementary Note 8) The substrate processing method according to any one of Supplementary Notes 1 to 7, wherein the silicon-containing film is a film obtained by adding nitrogen to any one of an amorphous silicon film, a polysilicon film, and a silicon film doped with at least one of phosphorus, boron, arsenic, antimony, aluminum, and gallium.(Supplementary Note 9) A structure having a pattern of a nitrogen-doped silicon-containing film formed on a first surface of a glass substrate by the substrate processing method according to any one of Supplements 1 to 8. (Supplementary Note 10) A film formation apparatus having a processing container and a control device, wherein the control device controls a process including: (a) providing a glass substrate having a first surface on which an optical element is to be formed and a second surface opposite to the first surface; and (b) simultaneously depositing nitrogen-doped silicon-containing films on the first and second surfaces of the glass substrate, controlling the amount of nitrogen doping so that the silicon-containing film formed on the first surface has a refractive index that allows it to function as the optical element, and the silicon-containing film formed on the second surface has a refractive index that allows the glass substrate to be detected by a sensor disposed in an apparatus used in a process subsequent to step (b). (Supplementary Note 11) A metalens having the structure according to Supplementary Note 9.

[0076] 1: Substrate processing system 2: Control device 3: Film forming device 4: Etching device 5: Processing device group 10: Glass substrate 10a: First surface 10b: Second surface 10c: Side surface 20: Nitrogen-added amorphous silicon film 20p: Nitrogen-added amorphous silicon film pattern 32: Processing vessel 40: Silicon oxide film 50: Hard mask 51: Spin-on carbon film 52: Spin-on glass film 60: Resist film 70: Protective film 100: Metalens 319: Sensor

Claims

1. A substrate processing method performed in a processing vessel by a film formation device, comprising: (a) providing a glass substrate having a first surface on which an optical element is formed and a second surface opposite the first surface; and (b) simultaneously forming nitrogen-doped silicon-containing films on the first and second surfaces of the glass substrate, wherein the amount of nitrogen added is controlled so that the silicon-containing film formed on the first surface has a refractive index that allows it to function as the optical element, and the silicon-containing film formed on the second surface has a refractive index that allows the glass substrate to be detected by a sensor disposed in a device used in processing subsequent to step (b).

2. The substrate processing method according to claim 1, wherein in the step (b), a silicon-containing gas and a nitrogen-containing gas are supplied into the processing vessel.

3. The substrate processing method according to claim 2, wherein the silicon-containing gas includes at least one of monosilane gas, disilane gas, trisilane gas, tetrasilane gas, dichlorosilane gas, hexachlorodisilane gas, tetrachlorosilane gas, trichlorosilane gas, bis(tert-butylamino)silane gas, and hexaethylaminodisilane gas.

4. The substrate processing method according to claim 2, wherein the nitrogen-containing gas contains at least one of ammonia gas, nitric oxide gas, and nitrogen dioxide gas.

5. The substrate processing method according to claim 1, further comprising the step of: (c) forming a pattern in the silicon-containing film deposited on the first surface.

6. The substrate processing method according to claim 5, further comprising the step of: (d) removing the silicon-containing film formed on the second surface after the step (c).

7. The substrate processing method according to claim 2, wherein the refractive index of the silicon-containing film is adjusted by controlling the flow rate of the nitrogen-containing gas relative to the total flow rate of the silicon-containing gas and the nitrogen-containing gas.

8. The substrate processing method according to any one of claims 1 to 7, wherein the silicon-containing film is a film obtained by adding nitrogen to any one of an amorphous silicon film, a polysilicon film, and a silicon film doped with at least one of phosphorus, boron, arsenic, antimony, aluminum, and gallium.

9. A structure in which a pattern of a nitrogen-doped silicon-containing film is formed on a first surface of a glass substrate by the substrate processing method according to any one of claims 1 to 7.

10. A film formation apparatus having a processing vessel and a control device, wherein the control device controls a process including the steps of: (a) providing a glass substrate having a first surface on which an optical element is formed and a second surface opposite to the first surface; and (b) simultaneously forming a nitrogen-doped silicon-containing film on the first surface and the second surface of the glass substrate, controlling the amount of nitrogen doped so that the silicon-containing film formed on the first surface has a refractive index that allows it to function as the optical element, and the silicon-containing film formed on the second surface has a refractive index that allows a sensor disposed in an apparatus used in a process subsequent to step (b) to detect the glass substrate.

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