WO2024084965A1

WO2024084965A1 - Diffraction grating formation method

Info

Publication number: WO2024084965A1
Application number: PCT/JP2023/036136
Authority: WO
Inventors: 卓也樋口; 文昭田中; 大樹前原
Original assignee: 東京エレクトロン株式会社
Priority date: 2022-10-18
Filing date: 2023-10-04
Publication date: 2024-04-25

Abstract

Provided is a technique for forming a diffraction grating using a high-refractive-index material.　This method for forming a diffraction grating on a substrate having permeability includes: (a) a step for forming, on the substrate, a first structure including recessed portions corresponding to protruding portions of the diffraction grating using a first material; (b) a step for providing a second material to the recessed portions of the first structure on the substrate to form a second structure including the diffraction grating; and (3) a step for removing the first structure.

Description

Method for forming a diffraction grating

An exemplary embodiment of the present disclosure relates to a method for forming a diffraction grating.

A technique for forming a diffraction grating using nanoimprinting is described in Patent Document 1.

US Patent Application Publication No. 2020/0333527

This disclosure provides a technique for forming a diffraction grating using a high refractive index material.

In one exemplary embodiment of the present disclosure, a method for forming a diffraction grating including protrusions on a transparent substrate includes the steps of: (a) forming a first structure on the substrate using a first material, the first structure including recesses corresponding to the protrusions of the diffraction grating; (b) providing a second material to the recesses of the first structure on the substrate to form a second structure including the diffraction grating; and (c) removing the first structure.

According to one exemplary embodiment of the present disclosure, a technique can be provided for forming a diffraction grating using a high refractive index material.

FIG. 1 is a diagram illustrating a configuration example of a glasses-type display device. 1 is a diagram for explaining a configuration example of an optical device included in a display device. 4 is a flowchart illustrating a method of forming a diffraction grating according to a first exemplary embodiment. 1 is a flowchart illustrating an example of a method for forming a first structure using a nanoimprint technique. 5A to 5C are schematic diagrams for explaining examples of steps of a method for forming a first structure using nanoimprint technology. 1 is a flow chart illustrating an example of a method for forming a first structure using photolithography techniques. 5A to 5C are schematic diagrams for explaining examples of steps of a method for forming a first structure using a photolithography technique. 10A to 10C are schematic diagrams for explaining examples of steps ST2 and ST3 in the method of forming a diffraction grating. 6 is a flowchart illustrating another example of the method for forming the diffraction grating in the first exemplary embodiment. 13A to 13C are schematic diagrams for explaining a step of forming a third structure. 5 is a flow chart illustrating a method of forming a diffraction grating according to a second exemplary embodiment. 5A to 5C are schematic diagrams for explaining each step of a method for forming a diffraction grating according to a second exemplary embodiment. FIG. 1 is a diagram for explaining a configuration example of a plasma processing system. FIG. 1 is a diagram for explaining a configuration example of a capacitively coupled plasma processing apparatus.

Each embodiment of the present disclosure is described below.

In one exemplary embodiment, a method for forming a diffraction grating including protrusions on a transparent substrate is provided, the method including the steps of: (a) forming a first structure on the substrate using a first material, the first structure including recesses corresponding to the protrusions of the diffraction grating; (b) providing a second material in the recesses of the first structure on the substrate to form a second structure including the diffraction grating; and (c) removing the first structure.

In one exemplary embodiment, the second material has a higher refractive index than the first material.

In one exemplary embodiment, the second material has a refractive index of 2 or greater.

In one exemplary embodiment, the first material includes a polymeric material.

In one exemplary embodiment, in step (a), the first structure is formed using nanoimprint technology or photolithography technology.

In one exemplary embodiment, step (b) includes depositing a second material on the first structure and removing an upper portion of the second material to expose the first structure.

In one exemplary embodiment, (d) further includes a step of providing a third material having a lower refractive index than the second material in the recesses formed by the protrusions of the diffraction grating of the second structure on the substrate by removing the first structure in step (c).

In one exemplary embodiment, step (d) includes planarizing the top surface of the second structure.

In one exemplary embodiment, the diffraction grating includes protrusions having an inclination angle greater than 0° and less than 90° relative to the surface of the substrate.

In one exemplary embodiment, a method for forming a diffraction grating including protrusions on a transparent substrate is provided, the method including: (a) forming a first structure including protrusions of the diffraction grating on the substrate using a first material; (b) providing a second material in recesses formed by the protrusions of the first structure on the substrate to form a second structure including protrusions; (c) removing the first structure; and (d) providing a third material in recesses formed by the protrusions of the second structure on the substrate as a result of removing the first structure in step (c) to form a third structure including the diffraction grating.

The third material has a refractive index higher than the refractive indexes of the first and second materials.

In one exemplary embodiment, the third material has a refractive index of 2 or greater.

In one exemplary embodiment, the first material includes a polymeric material.

In one exemplary embodiment, step (d) includes planarizing the top surface of the third structure.

Each embodiment of the present disclosure will be described in detail below with reference to the drawings. Note that identical or similar elements in each drawing will be given the same reference numerals, and duplicate explanations will be omitted. Unless otherwise specified, positional relationships such as up, down, left, right, etc. will be described based on the positional relationships shown in the drawings. The dimensional ratios in the drawings do not indicate actual ratios, and the actual ratios are not limited to the ratios shown in the drawings.

<Example of a display device>
1 is a diagram for explaining a configuration example of a display device 500. In one embodiment, the display device 500 may be a glasses type. In one embodiment, the display device 500 may be an augmented reality (AR) glass or a mixed reality (MR) glass.

In one embodiment, the display device 500 has a function of forming image light and outputting the image light to the user's eyes. FIG. 2 is a diagram for explaining an example of the configuration of an optical device included in the display device. In one embodiment, the display device 500 includes an image forming device 600 that forms image light from light from a light source, and an optical waveguide device 601 that guides the image light to the user's eyes. In one embodiment, the image forming device 600 includes a light emitting element such as an LED, a movable lens that polarizes light, and the like. In one embodiment, the image forming device 600 can be disposed on the rim 501, temple 502, endpiece 503, lens 504, or the peripheral parts thereof, of the display device (glasses) 500 shown in FIG. 1.

In one embodiment, the optical waveguide device 601 may be included in the lens 504 of the display device 500. As shown in FIG. 2, in one embodiment, the optical waveguide device 601 has a substrate 700 and a diffraction grating 701 formed on the substrate 700. The substrate 700 has a transmittance (transparency) that allows light to pass through. An example of the substrate 700 may be a glass substrate. The substrate 700 may be a substrate such as sapphire or SiC. The substrate 700 may be a bare substrate, or a substrate having a structure formed on the upper surface of the bare substrate. In one embodiment, the substrate 700 can guide image light inside the substrate 700 along the surface direction of the substrate 700, and can input external light from a first surface of the substrate 700 and output it from a second surface on the opposite side. A user of the display device 500 can simultaneously view an image formed by the image forming device 600 and an external image through the lens 504.

In one embodiment, the diffraction grating 701 is provided at least in two places on the surface of the substrate 700. The diffraction grating 701 includes a first diffraction grating section 710 that inputs the image light output from the image forming device 600, and a second diffraction grating section 711 that outputs the image light guided through the substrate 700 to the side of the user's eyes. In one embodiment, the first diffraction grating section 710 and the second diffraction grating section 711 are so-called oblique diffraction gratings. That is, in one embodiment, the first diffraction grating section 710 and the second diffraction grating section 711 have a shape (comb shape) having multiple convex portions 701a on the substrate 700, and the convex portions 701a are configured to protrude obliquely with respect to the substrate 700. The convex portions 701a of the first diffraction grating section 710 and the second diffraction grating section 711 have an inclination angle θ that is greater than 0° and less than 90° with respect to the surface of the substrate 700. In one embodiment, the convex portions 701a of the first diffraction grating portion 710 and the second diffraction grating portion 711 may be not oblique diffraction gratings but may have an angle of 90° with respect to the surface of the substrate 700. In one embodiment, the first diffraction grating portion 710 and the second diffraction grating portion 711 are provided on one surface of the substrate 700. In one embodiment, the first diffraction grating portion 710 and the second diffraction grating portion 711 are provided on the surface of the substrate 700 on the side where the user's eyes are located. The first diffraction grating portion 710 and the second diffraction grating portion 711 may be provided on both surfaces of the substrate 700. Hereinafter, a method for forming the diffraction grating 701 including the convex portions 701a on the substrate 700 will be described.

<An example of a method for forming a diffraction grating>
First Exemplary Embodiment
3 is a flow chart illustrating a method of forming a diffraction grating according to a first exemplary embodiment. In one embodiment, the method of forming a diffraction grating includes forming a first structure from a first material (ST1), forming a second structure from a second material (ST2), and removing the first structure (ST3).

In one embodiment, in step ST1, a first structure having a shape that is an inversion of the shape of the target diffraction grating 701 is formed. That is, in one embodiment, in step ST1, a first structure including recesses that correspond to the protrusions 701a of the diffraction grating 701 is formed. The first structure is made of a first material. In one embodiment, the first structure is formed using nanoimprint technology or photolithography technology.

<Nanoimprint Technology>
Fig. 4 is a flow chart showing an example of a method for forming a first structure using nanoimprint technology. Fig. 5 is a schematic diagram for explaining an example of each step of the method for forming a first structure using nanoimprint technology.

In one embodiment, step ST1 includes a step of preparing a substrate (ST1-1a), a step of forming a film (ST1-2a), a step of molding a first structure (ST1-3a), and a step of removing a residual film (ST1-4a).

In one embodiment, in step ST1-1a, a substrate 700 is prepared as shown in FIG. 5(a). In one embodiment, the substrate 700 is a transparent substrate. The substrate 700 may be a bare substrate or a bare substrate on which a structure is formed.

In one embodiment, in step ST1-2a, as shown in FIG. 5B, a film 800 including a first material is formed on a substrate 700. The first material includes a polymer material such as a resin. The first material may have a refractive index of less than 2, for example, 1.5 or less. The film 800 may be formed by a spin coating method or an inkjet method. The film 800 may be a resist film.

In one embodiment, in step ST1-3a, as shown in FIG. 5(c), the film 800 is pressed against a mold 801 having an uneven shape. With the mold 801 pressed against it, the film 800 is hardened by irradiation with ultraviolet light, heat treatment, or the like. As a result, the film 800 becomes uneven, and the first structure 810 is formed. At this time, excess residual film 802 remains on the substrate 700.

In one embodiment, in step ST1-4a, as shown in FIG. 5(d), the residual film 802 remaining on the substrate 700 is removed. The residual film 802 may be removed by etching. In this way, a first structure 810 made of a first material is formed on the substrate 700. The first structure 810 has a shape that is an inversion of the shape of the target diffraction grating 701. In other words, the first structure 810 has recesses 810a that correspond to the protrusions 701a of the diffraction grating 701.

<Photolithography Technology>
Fig. 6 is a flow chart showing an example of a method for forming a first structure using a photolithography technique. Fig. 7 is a schematic diagram for explaining an example of each step of the method for forming a first structure using a photolithography technique.

In one embodiment, step ST1 includes a step of preparing a substrate (ST1-1b), a step of forming a film (ST1-2b), a step of forming a mask film (ST1-3b), a step of etching the film (ST1-4b), and a step of removing the mask film (ST1-5b).

In one embodiment, in step ST1-1b, a substrate 700 is prepared as shown in FIG. 7(a). In one embodiment, the substrate 700 is a transparent substrate. The substrate 700 may be a bare substrate or a bare substrate on which a structure is formed.

In one embodiment, in step ST1-2b, as shown in FIG. 7B, a film 800 including a first material is formed on a substrate 700. The first material includes a polymer material such as a resin. The first material may have a refractive index of less than 2, for example, 1.5 or less. The film 800 may be formed by a spin coating method or an inkjet method. The film 800 may be a resist film.

In one embodiment, in step ST1-3b, as shown in FIG. 7C, a mask film 820 having a predetermined pattern is formed on the film 800. The mask film 820 may be formed by a photolithography method.

In one embodiment, in step ST1-4b, as shown in FIG. 7(d), the film 800 is etched using the mask film 820 as a mask. This removes the exposed portions of the film 800 where the mask film 820 is not present, and a groove is formed in the film 800, forming the first structure 810. The etching may be plasma etching or ion beam etching.

In one embodiment, in step ST1-5b, as shown in FIG. 7(e), the mask film 820 is removed. The mask film 820 may be removed by etching. Thus, a first structure 810 having a recess 810a is formed on the substrate 700.

In one embodiment, in step ST2 shown in FIG. 3, a second material is provided in the recess 810a (space) of the first structure 810 on the substrate 700, and a second structure having a protrusion 701a of the target diffraction grating 701 is formed. In one embodiment, the second material has a refractive index higher than that of the first material constituting the first structure 810. In one embodiment, the second material has a high refractive index of 2 or more. The second material may be a material other than a polymer. The second material may be an inorganic material. The second material may be TiOx, ZrOx, HfOx, or SiN, or may be a mixture of two or more selected from them. The second material may be a further mixture of SiO2 and AlO2. FIG. 8 is a schematic diagram for explaining an example of steps ST2 and ST3 of the method for forming a diffraction grating.

In one embodiment, in step ST2, first, as shown in FIG. 8A, a film of the second material 830 is formed on the first structure 810. In one embodiment, the second material 830 penetrates into the recess 810a of the first structure 810 and is also deposited on the upper surface of the first structure 810. The film of the second material 830 may be formed by a sputtering method, a CVD method, an ALD (Atomic Layer Deposition) method, an evaporation method, or a spin coating method.

In one embodiment, next in step ST2, as shown in FIG. 8B, the upper portion of the deposited second material 830 is removed to expose the upper surface of the first structure 810. In one embodiment, the upper surface of the second material 830 may be polished and planarized to expose the upper surface of the first structure 810. At this time, the second material 830 becomes the second structure 830 having the convex portion 701a of the target diffraction grating 701. In this way, the second structure 830 having the convex portion 701a is formed in the concave portion 810a of the first structure 810 on the substrate 700.

In one embodiment, in step ST3 (shown in FIG. 3), the first structure 810 is removed as shown in FIG. 8(c). The first structure 810 may be removed by etching, ashing, or liquid cleaning. Thus, the second structure 830 remains on the substrate 700, and a diffraction grating 701 having a target shape is formed.

According to this exemplary embodiment, a method for forming a diffraction grating 701 including a convex portion 701a on a substrate 700 includes the steps of: (a) forming a first structure 810 including a concave portion 810a corresponding to the convex portion 701a of a target diffraction grating on the substrate 700 using a first material; (b) providing a second material having a higher refractive index than the first material to the concave portion 810a of the first structure 810 on the substrate 700 to form a second structure 830 including the convex portion 701a of the diffraction grating 701; and (c) removing the first structure 810. As a result, the first structure 810 is formed using a first material that is easy to mold, and then the second structure 830 is formed using a second material having a high refractive index material, and the first structure 810 is removed to form the diffraction grating 701. As a result, a diffraction grating can be formed using a high refractive index material. In addition, the degree of freedom of the shape of the diffraction grating is improved.

The first material contains a polymer material, so that the first structure 810 can be easily formed using a nanoimprinting method or the like. And the second material has a refractive index of 2 or more, so that a diffraction grating with a high refractive index can be realized.

In this exemplary embodiment, the diffraction grating 701 includes a convex portion 701a having an inclination angle θ of more than 0° and less than 90° with respect to the surface of the substrate 700. In one embodiment, the diffraction grating 701 has a comb-tooth shape having a plurality of convex portions 701a that protrude obliquely with respect to the substrate 700. Alternatively, the diffraction grating 701 may have an angle of 90° with respect to the surface of the substrate 700. According to the method for forming a diffraction grating in this exemplary embodiment, the convex portions 701 of the diffraction grating 701 can be easily formed even if they are oblique. That is, when a diffraction grating is formed by performing dry etching or the like on a film on a substrate, the direction of the etching is determined by the pull-in electric field perpendicular to the substrate, so it is difficult to form a structure having convex portions oblique to the substrate. In addition, when a diffraction grating is formed by performing wet etching on a film on a substrate, there is no anisotropy of the etching, and it is not possible to form a structure having oblique convex portions. Furthermore, when an oblique diffraction grating is formed on a film on a substrate using ion beam etching or the like, it is necessary to scan the ion beam with respect to the substrate, and it takes time to process the entire surface of the substrate, which results in poor productivity.

In the first exemplary embodiment, as shown in FIG. 9, the method for forming a diffraction grating may further include a step (ST4) of forming a third structure with a third material. FIG. 10 is a schematic diagram for explaining an example of step ST4.

In one embodiment, in step ST4, a third material having a lower refractive index than the second material is provided in a recess (space) formed by the protrusion 701a of the second structure 830 on the substrate 700, to form a third structure. The third material may be a material having a lower refractive index than the second material. The third material may have a refractive index of less than 2. The third material may be an inorganic material. The third material may be SiO2, Al2O3, or a mixture thereof.

In one embodiment, in step ST4, first, as shown in FIG. 10A, a film of a third material 840 is formed on the second structure 830. In one embodiment, the third material 840 penetrates into the recesses 830a formed by the protrusions 701a of the second structure 830, and is also deposited on the upper surface of the second structure 830. The film of the third material 840 may be formed by a sputtering method, a CVD method, an ALD (Atomic Layer Deposition) method, an evaporation method, or a spin coating method.

In one embodiment, next in step ST4, as shown in FIG. 10(b), the upper portion of the deposited third material 840 is removed to expose the upper surface of the second structure 830. In one embodiment, the upper surfaces of the third material 840 and the second structure 830 may be polished and planarized to expose the upper surface of the second structure 830. At this time, the third material 840 becomes the third structure. In this way, the third structure 840 is formed in the recess 830a formed by the protrusion 701a of the second structure 830 on the substrate 700.

According to this exemplary embodiment, it is possible to realize a diffraction grating 701 with high light guiding efficiency.

Second Exemplary Embodiment
11 is a flowchart showing a method for forming a diffraction grating according to a second exemplary embodiment. In the second exemplary embodiment, a diffraction grating 701 similar to that of the first exemplary embodiment is formed. FIG. 12 is a schematic diagram for explaining each step of the method for forming a diffraction grating according to the second exemplary embodiment. The method for forming a diffraction grating includes a step (ST1a) of forming a first structure with a first material, a step (ST2a) of forming a second structure with a second material, a step (ST3a) of removing the first structure, and a step (ST4a) of forming a third structure with a third material.

In one embodiment, in step ST1a, as shown in FIG. 12(a), a first structure 810 is formed that includes a convex portion 810b having a shape similar to that of the convex portion 701a of the target diffraction grating 701. In one embodiment, the first structure 810 is formed using nanoimprint technology or photolithography technology. The method of forming the first structure 810 using nanoimprint technology or photolithography technology may be the same as that of the first exemplary embodiment described above.

In one embodiment, in step ST2a, a second material is provided in a recess (space) formed by a protrusion 810b of a first structure 810 on a substrate 700, and a second structure having a protrusion 830b is formed. In one embodiment, the second material has a low refractive index of less than 2. The second material may be a material other than a polymer. The second material may be an inorganic material. The second material may be SiO2, Al2O3, or a mixture thereof.

In one embodiment, in step ST2, first, as shown in FIG. 12(b), a film of the second material 830 is formed on the first structure 810. In one embodiment, the second material 830 penetrates into the recesses formed by the protrusions 810b of the first structure 810, and is also deposited on the upper surface of the first structure 810. The film of the second material 830 may be formed by a sputtering method, a CVD method, an ALD (Atomic Layer Deposition) method, an evaporation method, or a spin coating method.

In one embodiment, next in step ST2, as shown in FIG. 12(c), the upper portion of the deposited second material 830 is removed to expose the upper surface of the first structure 810. In one embodiment, the upper surface of the second material 830 may be polished and planarized to expose the upper surface of the first structure 810. At this time, the second material 830 becomes the second structure 830 having the convex portion 830b. In this way, the second structure 830 including the convex portion 830b is formed in the concave portion formed by the convex portion 810b of the first structure 810 on the substrate 700.

In one embodiment, in step ST3, the first structure 810 is removed as shown in FIG. 12(d). The first structure 810 may be removed by etching, ashing, or liquid cleaning. Thus, the second structure 830 having the protrusion 830b remains on the substrate 700.

In one embodiment, in step ST4, a third material is provided in a recess (space) formed by the protrusion 830b of the second structure 830 on the substrate 700 to form a third structure including the protrusion 701a of the target diffraction grating 701. In one embodiment, the third material has a refractive index higher than the refractive index of the first material constituting the first structure 810 and the second material constituting the second structure 830. In one embodiment, the third material has a high refractive index of 2 or more. The third material may be a material other than a polymer. The third material may be an inorganic material. The third material may be TiOx, ZrOx, HfOx, or SiN, or may be a mixture of two or more selected from them. The third material may be a further mixture of SiO2 and AlO2.

In one embodiment, in step ST4, first, as shown in FIG. 12(e), a film of a third material 840 is formed on the second structure 830. In one embodiment, the third material 840 penetrates into the recesses formed by the protrusions 830b of the second structure 830, and is also deposited on the upper surface of the second structure 830. The film of the third material 840 may be formed by a sputtering method, a CVD method, an ALD (Atomic Layer Deposition) method, an evaporation method, or a spin coating method.

In one embodiment, next in step ST4, as shown in FIG. 12(f), the upper portion of the deposited third material 840 is removed to expose the upper surface of the second structure 830. In one embodiment, the upper surfaces of the third material 840 and the second structure 830 may be polished and planarized to expose the upper surface of the second structure 830. At this time, the third material 840 becomes a third structure having the convex portion 701a of the target diffraction grating 701. In this way, a diffraction grating 701 having a third material with a high refractive index is formed on the substrate 700.

According to this exemplary embodiment, a method for forming a diffraction grating 701 includes the steps of (a) forming a first structure 810 including a convex portion 810b (701a) of a target diffraction grating 701 on a substrate 700 using a first material; (b) providing a second material in a recess formed by the convex portion 810b of the first structure 810 on the substrate 700 to form a second structure 830 including a convex portion 830b; (c) removing the first structure 810; and (d) providing a third material having a refractive index higher than the first material and the second material in a recess formed by the convex portion 830b of the second structure 830 on the substrate 700 to form a third structure 840 including a convex portion 701a of the diffraction grating 701. This allows the first structure 810 to be formed from a first material that is easy to mold, then the second structure 830 to be formed from a second material, the third structure 840 to be formed from a third material having a high refractive index, and the second structure 830 to be removed, thereby forming a diffraction grating 701 having a third material with a high refractive index. This allows the diffraction grating to be formed using a high refractive index material. In addition, the degree of freedom in the shape of the diffraction grating is improved.

The first material contains a polymer material, so that the first structure 810 can be easily formed using a nanoimprinting method or the like. And the third material has a refractive index of 2 or more, so that a diffraction grating with a high refractive index can be realized.

The method for forming the diffraction grating in this exemplary embodiment makes it easy to form the diffraction grating 701 even if the protrusions 701 are oblique.

The diffraction grating forming methods in the first and second exemplary embodiments may be performed using a substrate processing system. The substrate processing system may include a plasma processing system that processes a substrate using plasma.

<An example of a plasma processing system>
FIG. 13 is a diagram for explaining a configuration example of a plasma processing system. In one embodiment, the plasma processing system includes a plasma processing device 1 and a control unit 2. The plasma processing system is an example of a substrate processing system, and the plasma processing device 1 is an example of a substrate processing device. The plasma processing device 1 includes a plasma processing chamber 10, a substrate support unit 11, and a plasma generation unit 12. The plasma processing chamber 10 has a plasma processing space. The plasma processing chamber 10 also has at least one gas supply port for supplying at least one processing gas to the plasma processing space, and at least one gas exhaust port for exhausting gas from the plasma processing space. The gas supply port is connected to a gas supply unit 20 described later, and the gas exhaust port is connected to an exhaust system 40 described later. The substrate support unit 11 is disposed in the plasma processing space, and has a substrate support surface for supporting a substrate.

The plasma generating unit 12 is configured to generate plasma from at least one processing gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be capacitively coupled plasma (CCP), inductively coupled plasma (ICP), ECR plasma (Electron-Cyclotron-resonance plasma), Helicon wave excited plasma (HWP: Helicon Wave Plasma), or surface wave plasma (SWP: Surface Wave Plasma), etc. In addition, various types of plasma generating units may be used, including an AC (Alternating Current) plasma generating unit and a DC (Direct Current) plasma generating unit. In one embodiment, the AC signal (AC power) used in the AC plasma generation unit has a frequency in the range of 100 kHz to 10 GHz. Thus, the AC signal includes an RF (Radio Frequency) signal and a microwave signal. In one embodiment, the RF signal has a frequency in the range of 100 kHz to 150 MHz.

The control unit 2 processes computer-executable instructions that cause the plasma processing apparatus 1 to perform the various steps described in this disclosure. The control unit 2 may be configured to control each element of the plasma processing apparatus 1 to perform the various steps described herein. In one embodiment, a part or all of the control unit 2 may be included in the plasma processing apparatus 1. The control unit 2 may include, for example, a computer 2a. The computer 2a may include, for example, a processing unit (CPU: Central Processing Unit) 2a1, a storage unit 2a2, and a communication interface 2a3. The processing unit 2a1 may be configured to perform various control operations by reading a program from the storage unit 2a2 and executing the read program. This program may be stored in the storage unit 2a2 in advance, or may be acquired via a medium when necessary. The acquired program is stored in the storage unit 2a2, and is read from the storage unit 2a2 by the processing unit 2a1 and executed. The medium may be various storage media readable by the computer 2a, or may be a communication line connected to the communication interface 2a3. The memory unit 2a2 may include a RAM (Random Access Memory), a ROM (Read Only Memory), a HDD (Hard Disk Drive), a SSD (Solid State Drive), or a combination of these. The communication interface 2a3 may communicate with the plasma processing device 1 via a communication line such as a LAN (Local Area Network).

Below, we will explain a configuration example of a capacitively coupled plasma processing device as an example of the plasma processing device 1. Figure 14 is a diagram for explaining a configuration example of a capacitively coupled plasma processing device.

The capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10, a gas supply unit 20, a power supply 30, and an exhaust system 40. The plasma processing apparatus 1 also includes a substrate support unit 11 and a gas inlet unit. The gas inlet unit is configured to introduce at least one processing gas into the plasma processing chamber 10. The gas inlet unit includes a shower head 13. The substrate support unit 11 is disposed in the plasma processing chamber 10. The shower head 13 is disposed above the substrate support unit 11. In one embodiment, the shower head 13 constitutes at least a part of the ceiling of the plasma processing chamber 10. The plasma processing chamber 10 has a plasma processing space 10s defined by the shower head 13, the sidewall 10a of the plasma processing chamber 10, and the substrate support unit 11. The plasma processing chamber 10 is grounded. The shower head 13 and the substrate support unit 11 are electrically insulated from the plasma processing chamber 10 housing.

The substrate support 11 includes a main body 111 and a ring assembly 112. The main body 111 has a central region 111a for supporting the substrate W and an annular region 111b for supporting the ring assembly 112. A wafer is an example of a substrate W. The substrate W includes a substrate 700. The annular region 111b of the main body 111 surrounds the central region 111a of the main body 111 in a plan view. The substrate W is disposed on the central region 111a of the main body 111, and the ring assembly 112 is disposed on the annular region 111b of the main body 111 so as to surround the substrate W on the central region 111a of the main body 111. Therefore, the central region 111a is also called a substrate support surface for supporting the substrate W, and the annular region 111b is also called a ring support surface for supporting the edge ring assembly 112.

In one embodiment, the main body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 may function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a ceramic member 1111a and an electrostatic electrode 1111b disposed within the ceramic member 1111a. The ceramic member 1111a has a central region 111a. In one embodiment, the ceramic member 1111a also has an annular region 111b. Note that other members surrounding the electrostatic chuck 1111, such as an annular electrostatic chuck or an annular insulating member, may have the annular region 111b. In this case, the ring assembly 112 may be disposed on the annular electrostatic chuck or the annular insulating member, or may be disposed on both the electrostatic chuck 1111 and the annular insulating member. Also, an RF or DC electrode may be disposed within the ceramic member 1111a, in which case the RF or DC electrode functions as the lower electrode. When a bias RF signal or DC signal, which will be described later, is connected to the RF or DC electrode, the RF or DC electrode is also called a bias electrode. Note that both the conductive member of the base 1110 and the RF or DC electrode may function as two lower electrodes.

The ring assembly 112 includes one or more annular members. In one embodiment, the one or more annular members include one or more edge rings and at least one cover ring. The edge rings are formed of a conductive or insulating material, and the cover rings are formed of an insulating material.

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

The shower head 13 is configured to introduce at least one processing gas from the gas supply unit 20 into the plasma processing space 10s. The shower head 13 has at least one gas supply port 13a, at least one gas diffusion chamber 13b, and multiple gas inlets 13c. The processing gas supplied to the gas supply port 13a passes through the gas diffusion chamber 13b and is introduced into the plasma processing space 10s from the multiple gas inlets 13c. The shower head 13 also includes an upper electrode. Note that the gas introduction unit may include, in addition to the shower head 13, one or more side gas injectors (SGI) attached to one or more openings formed in the side wall 10a.

The gas supply unit 20 may include at least one gas source 21 and at least one flow controller 22. In one embodiment, the gas supply unit 20 is configured to supply at least one process gas from a respective gas source 21 through a respective flow controller 22 to the showerhead 13. Each flow controller 22 may include, for example, a mass flow controller or a pressure-controlled flow controller. Additionally, the gas supply unit 20 may include at least one flow modulation device that modulates or pulses the flow rate of the at least one process gas.

The power supply 30 includes an RF power supply 31 coupled to the plasma processing chamber 10 via at least one impedance matching circuit. The RF power supply 31 is configured to supply at least one RF signal (RF power), such as a source RF signal and a bias RF signal, to at least one lower electrode and/or at least one upper electrode. This causes a plasma to be formed from at least one processing gas supplied to the plasma processing space 10s. Thus, the RF power supply 31 can function as at least a part of the plasma generating unit 12. In addition, by supplying a bias RF signal to at least one lower electrode, a bias potential is generated on the substrate W, and ion components in the formed plasma can be attracted to the substrate W.

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

The second RF generator 31b is coupled to at least one lower electrode via at least one impedance matching circuit and configured to generate a bias RF signal (bias RF power). The frequency of the bias RF signal may be the same as or different from the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency lower than the frequency of the source RF signal. In one embodiment, the bias RF signal has a frequency in the range of 100 kHz to 60 MHz. In one embodiment, the second RF generator 31b may be configured to generate multiple bias RF signals having different frequencies. The generated one or more bias RF signals are provided to at least one lower electrode. Also, in various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.

The power supply 30 may also include a DC power supply 32 coupled to the plasma processing chamber 10. The DC power supply 32 includes a first DC generator 32a and a second DC generator 32b. In one embodiment, the first DC generator 32a is connected to at least one lower electrode and configured to generate a first DC signal. The generated first DC signal is applied to the at least one lower electrode. In one embodiment, the second DC generator 32b is connected to at least one upper electrode and configured to generate a second DC signal. The generated second DC signal is applied to the at least one upper electrode.

In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of DC-based voltage pulses is applied to at least one lower electrode and/or at least one upper electrode. The voltage pulses may have a rectangular, trapezoidal, triangular or combination of these pulse waveforms. In one embodiment, a waveform generator for generating a sequence of voltage pulses from the DC signal is connected between the first DC generator 32a and at least one lower electrode. Thus, the first DC generator 32a and the waveform generator constitute a voltage pulse generator. When the second DC generator 32b and the waveform generator constitute a voltage pulse generator, the voltage pulse generator is connected to at least one upper electrode. The voltage pulses may have a positive polarity or a negative polarity. Also, the sequence of voltage pulses may include one or more positive polarity voltage pulses and one or more negative polarity voltage pulses within one period. The first and second

DC generating units

32a and 32b may be provided in addition to the RF power source 31, or the first DC generating unit 32a may be provided in place of the second RF generating unit 31b.

The exhaust system 40 may be connected to, for example, a gas exhaust port 10e provided 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 in the plasma processing space 10s is adjusted by the pressure regulating valve. The vacuum pump may include a turbomolecular pump, a dry pump, or a combination thereof.

<An example of plasma treatment>
The plasma processing performed by using the plasma processing apparatus 1 includes an etching process for etching a film on the substrate W using plasma and a film deposition process for forming a film on the substrate W. In one embodiment, the plasma processing is executed by a controller 2.

First, the substrate W is carried into the chamber 10 by the transport arm, placed on the substrate support 11 by the lifter, and held by suction on the substrate support 11 as shown in FIG. 14.

Next, the processing gas is supplied to the shower head 13 by the gas supply unit 20, and is supplied from the shower head 13 to the plasma processing space 10s. The processing gas supplied at this time includes a gas that generates active species required for etching and film formation processing of the substrate W.

One or more RF signals are supplied from the RF power supply 31 to the upper electrode and/or the lower electrode. The atmosphere in the plasma processing space 10s is exhausted from the gas exhaust port 10e, and the inside of the plasma processing space 10s may be depressurized. This generates plasma in the plasma processing space 10s, and the substrate W is plasma processed.

In the plasma processing apparatus 1, the steps of (b) forming the second structure 830, (c) removing the first structure 810, and (d) forming the third structure 840 in the above-mentioned diffraction grating forming method may be performed. The steps of (b) forming the second structure 830 and (d) forming the third structure 840 may be performed by a film forming apparatus that performs CVD (Chemical Vapor Deposition) or ALD (Atomic Layer Deposition) or a spin coating apparatus. The film forming apparatus may be either a single-wafer type or a batch type. The step of (a) forming the first structure 810 may be performed by a photolithography apparatus or a nanoimprint apparatus. The substrate processing system may include the above-mentioned film forming apparatus, a photolithography apparatus, a spin coating apparatus, a nanoimprint apparatus, etc.

The shape of the diffraction grating 701 and the position and number on the substrate 700 are not limited to those in the above exemplary embodiment. The display device 500 and optical waveguide device 601 in which the diffraction grating 701 is used are not limited to those in the above exemplary embodiment.

In the above exemplary embodiments, the method of forming the diffraction grating may be modified in various ways without departing from the scope and spirit of the present disclosure. For example, some components in one embodiment may be added to another embodiment within the scope of the ordinary creative ability of a person skilled in the art. Also, some components in one embodiment may be replaced with corresponding components in another embodiment. The present disclosure may include, for example, the following configurations.

(Appendix 1)
A method for forming a diffraction grating including protrusions on a transparent substrate, comprising the steps of:
(a) forming a first structure on the substrate using a first material, the first structure including recesses corresponding to the protrusions of the diffraction grating;
(b) providing a second material in the recess of the first structure on the substrate to form a second structure including the diffraction grating;
(c) removing the first structure;
A method for forming a diffraction grating, comprising:

(Appendix 2)
2. The method of claim 1, wherein the second material has a refractive index higher than a refractive index of the first material.

(Appendix 3)
3. The method for forming a diffraction grating according to claim 1, wherein the second material has a refractive index of 2 or more.

(Appendix 4)
4. The method of claim 1, wherein the first material comprises a polymer material.

(Appendix 5)
5. The method for forming a diffraction grating according to claim 1, wherein in the step (a), the first structure is formed using a nanoimprint technique or a photolithography technique.

(Appendix 6)
The step (b) comprises:
depositing the second material over the first structure;
and removing an upper portion of the second material to expose the first structure.

(Appendix 7)
(d) providing a third material having a lower refractive index than the second material in recesses formed by the protrusions of the diffraction grating of the second structure on the substrate by removing the first structure in step (c).

(Appendix 8)
8. The method for forming a diffraction grating of claim 7, wherein step (d) includes the step of planarizing an upper surface of the second structure.

(Appendix 9)
8. The method for forming a diffraction grating according to claim 1, wherein the diffraction grating includes the convex portions having an inclination angle of more than 0° and less than 90° with respect to a surface of the substrate.

(Appendix 10)
A method for forming a diffraction grating including protrusions on a transparent substrate, comprising the steps of:
(a) forming a first structure including the protrusions of the diffraction grating on the substrate using a first material;
(b) providing a second material in a recess formed by the protrusion of the first structure on the substrate to form a second structure including a protrusion;
(c) removing the first structure;
(d) providing a third material in a recess formed by the protrusion of the second structure on the substrate as a result of removing the first structure in the (c) step, thereby forming a third structure including the diffraction grating;
A method for forming a diffraction grating, comprising:

(Appendix 11)
11. The method of forming a diffraction grating of claim 10, wherein the third material has a refractive index higher than the refractive indexes of the first material and the second material.

(Appendix 12)
12. The method for forming a diffraction grating according to claim 10 or 11, wherein the third material has a refractive index of 2 or more.

(Appendix 13)
13. The method of forming a diffraction grating of any one of claims 10 to 12, wherein the first material comprises a polymer material.

(Appendix 14)
14. The method for forming a diffraction grating according to claim 10, wherein in the step (a), the first structure is formed using a nanoimprint technique or a photolithography technique.

(Appendix 15)
The step (b) comprises:
depositing the second material over the first structure;
and removing an upper portion of the second material to expose the first structure.

(Appendix 16)
16. The method for forming a diffraction grating according to any one of claims 10 to 15, wherein the step (d) includes a step of planarizing an upper surface of the third structure.

(Appendix 17)
17. The method for forming a diffraction grating according to claim 10, wherein the diffraction grating includes the convex portions having an inclination angle of more than 0° and less than 90° with respect to a surface of the substrate.

500: display device, 700: substrate, 701: diffraction grating, 701a: protrusion, 810: first structure, 830: second structure, 840: third structure

Claims

A method for forming a diffraction grating including protrusions on a transparent substrate, comprising the steps of:
(a) forming a first structure on the substrate using a first material, the first structure including recesses corresponding to the protrusions of the diffraction grating;
(b) providing a second material in the recess of the first structure on the substrate to form a second structure including the diffraction grating;
(c) removing the first structure;
A method for forming a diffraction grating, comprising:
The method for forming a diffraction grating according to claim 1, wherein the second material has a refractive index higher than the refractive index of the first material.
The method for forming a diffraction grating according to claim 1, wherein the second material has a refractive index of 2 or more.
The method for forming a diffraction grating according to claim 1, wherein the first material includes a polymer material.
The method for forming a diffraction grating according to claim 1, wherein in step (a), the first structure is formed using nanoimprint technology or photolithography technology.
The step (b) comprises:
depositing the second material over the first structure;
and removing an upper portion of the second material to expose the first structure.
The method for forming a diffraction grating according to claim 1, further comprising the step of: (d) providing a third material having a lower refractive index than the second material in the recesses formed by the protrusions of the diffraction grating of the second structure on the substrate by removing the first structure in the step (c).
The method for forming a diffraction grating according to claim 7, wherein step (d) includes a step of planarizing the upper surface of the second structure.
The method for forming a diffraction grating according to claim 1, wherein the diffraction grating includes protrusions having an inclination angle greater than 0° and less than 90° with respect to the surface of the substrate.
A method for forming a diffraction grating including protrusions on a transparent substrate, comprising the steps of:
(a) forming a first structure including the protrusions of the diffraction grating on the substrate using a first material;
(b) providing a second material in a recess formed by the protrusion of the first structure on the substrate to form a second structure including a protrusion;
(c) removing the first structure;
(d) providing a third material in a recess formed by the protrusion of the second structure on the substrate as a result of removing the first structure in the (c) step, thereby forming a third structure including the diffraction grating;
A method for forming a diffraction grating, comprising:
The method for forming a diffraction grating according to claim 10, wherein the third material has a refractive index higher than the refractive indexes of the first material and the second material.
The method for forming a diffraction grating according to claim 10, wherein the third material has a refractive index of 2 or more.
The method for forming a diffraction grating according to claim 10, wherein the first material includes a polymer material.
The method for forming a diffraction grating according to claim 10, wherein in step (a), the first structure is formed using nanoimprint technology or photolithography technology.
The step (b) comprises:
depositing the second material over the first structure;
and removing an upper portion of the second material to expose the first structure.
The method for forming a diffraction grating according to claim 10, wherein step (d) includes a step of planarizing an upper surface of the third structure.
The method for forming a diffraction grating according to claim 10 , wherein the diffraction grating includes the protrusions having an inclination angle greater than 0° and less than 90° with respect to a surface of the substrate.