Method and apparatus for greyscale lithography

Abstract

An image projection system is provided. This system can be used to perform lithography. The system includes a deuterium light source and a converging lens coupled to the deuterium light source. The system includes an aperture configured to provide image blocking, the aperture being disposed adjacent to the converging lens. The system includes a movable platform adjacent to the aperture. A method of manufacturing an optical device is provided. The method includes depositing a resist on a substrate and determining an exposure pattern for the optical device. The method includes exposing a portion of the resist with a light beam based on the determined exposure pattern. Exposing this portion of the resist includes guiding the light beam from the deuterium light source to the substrate and developing the resist.

Description

[Technical Field]

[0001] The embodiments of this invention generally relate to optical devices for augmented, virtual, and mixed reality. More specifically, the embodiments described herein provide systems and methods for fabricating optical devices using grayscale lithography. [Previous Technology]

[0002] Virtual reality is generally considered to be a computer-generated simulated environment in which the user has an apparent physical presence. Virtual reality experiences can be generated in three dimensions (3D) and used for viewing on head-mounted displays (HMDs), such as glasses or other wearable display devices with near-eye display panels (such as lenses), to display virtual reality environments that replace the real environment.

[0003] However, augmented reality enables users to see their surroundings through the display lenses of glasses or other HMD devices, or handheld devices, and to see images of virtual objects generated on the display and appearing as part of the environment. Augmented reality can include any type of input, such as audio and haptic input, as well as virtual images, graphics, and visuals of the environment that can enhance or augment the user experience. As an emerging technology, augmented reality faces many challenges and design constraints.

[0004] One such challenge is displaying a virtual image superimposed on the surrounding environment. Optical devices are used to assist in the superimposed image. The generated light propagates through a waveguide until it leaves the waveguide and superimposes on the surrounding environment. Manufacturing optical devices can be challenging because they tend to have non-uniform characteristics. Therefore, there is a need in this art for improved systems and methods for manufacturing optical devices. [Summary of the Invention]

[0005] In some embodiments, an image projection system is provided. This system can be used to perform lithography. The system includes a deuterium light source and a converging lens coupled to the deuterium light source. The system includes an aperture disposed adjacent to the converging lens. The system includes a movable platform disposed adjacent to the aperture.

[0006] In some embodiments, an image projection system for performing lithography is provided. The system includes a deuterium source comprising an array of deuterium sources. The system includes an elliptical reflector downstream of the deuterium source along a beam path from the deuterium source. The system includes an optical integrator disposed downstream of the elliptical reflector, a mirror disposed downstream of the optical integrator, and a collimating lens disposed downstream of the mirror. The system includes a platform disposed downstream of the collimating lens.

[0007] In some embodiments, a method of manufacturing an optical device is provided. The method includes depositing a resist on a substrate and determining an exposure pattern for the optical device. The method includes exposing a portion of the resist with a light beam based on the determined exposure pattern. Exposing this portion of the resist involves guiding the light beam from a deuterium light source to the substrate and developing the resist.

Implementation Method

[0014] The embodiments described herein provide a system, software application, and method for writing grayscale portions in a lithography process (e.g., a digital lithography process). One embodiment of the system includes a controller configured to provide mask pattern data to the lithography system. The mask pattern data has a plurality of grayscale exposure polygons. The lithography system has a processing unit having a plurality of image projection systems that receive the mask pattern data. Each image projection system includes a spatial light modulator having a plurality of spatial light modulator pixels for projecting a plurality of lenses. The controller is configured to temporally divide the plurality of spatial light modulator pixels through the grayscale lenses of the plurality of lenses, and the controller is configured to change the intensity of a beam of light generated by a deuterium source by each image projection system at the grayscale lens.

[0015] Figure 1 is a perspective view of a system 100 (such as a digital lithography system) that may benefit from the embodiments described herein. System 100 includes a platform 114 and a processing device 104. In some embodiments, the platform 114 is supported by a pair of tracks 116 mounted on a flat plate 102. A substrate 101 is supported by the platform 114. The platform 114 is supported by a pair of tracks 116 mounted on a flat plate 102. The platform 114 moves along the pair of tracks 116 in the X-axis direction, as shown by the coordinate system shown in Figure 1. In one embodiment that may be combined with other embodiments described herein, the pair of tracks 116 is a pair of parallel magnetic channels. As shown, each track in the pair of tracks 116 extends in a straight path. An encoder 118 is coupled to the platform 114 to provide position information of the platform 114 to a controller 122. In some embodiments, the platform 114 is coupled to an actuator and is movable in the x-axis, y-axis, and z-axis directions. In some embodiments, the platform 114 may move using magnetic levitation without using tracks (not shown).

[0016] Controller 122 is generally designed to facilitate the control and automation of the processing techniques described herein. Controller 122 may be coupled to or communicate with processing device 104, platform 112, and encoder 118. Processing device 104 and encoder 118 may provide controller 122 with information regarding substrate processing and substrate alignment. For example, processing device 104 may provide information to controller 122 to alert controller 122 that substrate processing has been completed. Controller 122 facilitates the control and formation of the grayscale lithography method. A program (or computer instructions) readable by controller 122, which may be called an imaging program, determines which tasks can be performed on substrate 101. The program includes mask pattern data and codes for monitoring and controlling processing time and substrate position. The mask pattern data corresponds to a pattern written into photoresist by electromagnetic radiation to be used.

[0017] The substrate 101 comprises any suitable material, such as glass, which is used as part of a wearable display device. In other embodiments that may be combined with other embodiments described herein, the substrate 101 is made of other materials that can be used as part of a wearable display device. The substrate 101 has a thin film layer to be patterned thereon, such as by pattern etching thereon; and a photoresist layer formed on the thin film layer to be patterned, which is sensitive to electromagnetic radiation such as ultraviolet or deep ultraviolet "light". A positive photoresist comprises portions of a photoresist that, when exposed to radiation, are soluble in a photoresist developer applied to the photoresist after a pattern has been written into the photoresist using electromagnetic radiation. A negative photoresist comprises portions of a photoresist that, when exposed to radiation, are insoluble in a photoresist developer applied to the photoresist after a pattern has been written into the photoresist using electromagnetic radiation. The chemical composition of the photoresist determines whether the photoresist is a positive or negative photoresist. Examples of photoresists include, but are not limited to, at least one of diazonaphthoquinone, phenolic resin, poly(methyl methacrylate) (PMMA), poly(methylpentadieneimide), and SU-8. After exposing the photoresist to electromagnetic radiation, the photoresist is developed to leave a patterned photoresist on the underlying thin film layer. Then, using the patterned photoresist, the underlying thin film is patterned and etched through openings in the photoresist to form part of the electronic circuitry of the display panel.

[0018] The processing device 104 includes a support 108 and a processing unit 106. The processing device 104 spans over a pair of guide rails 116 and is mounted on a plate 102, and thus includes an opening 112 for the passage of the pair of guide rails 116 and platform 114 below the processing unit 106. The processing unit 106 is supported on the plate 102 via the support 108. In one embodiment that may be combined with other embodiments described herein, the processing unit 106 is a pattern generator configured to expose photoresist in a photolithography process. In some embodiments that may be combined with other embodiments described herein, the pattern generator is configured to perform a maskless photolithography process. The processing unit 106 includes a plurality of image projection systems. Examples of image projection systems are shown in Figures 2 and 3. In some embodiments, each image projection system is housed in a housing 110. Alternatively, the processing device 104 includes a single image projection system. The processing unit 106 is used to perform maskless direct pattern writing on photoresist or other electromagnetically sensitive materials.

[0019] Figure 2 is a schematic diagram of an image projection system 200. System 200 is operable to perform grayscale lithography on a resist to create an optical device. System 200 includes a deuterium light source 202, a housing 206, and a platform 214, such as platform 114 shown in Figure 1. The deuterium light source 202 is operable to produce light with wavelengths of approximately 120 nm to approximately 900 nm, such as approximately 180 nm to approximately 370 nm, and such as approximately 200 nm to approximately 315 nm. Without being bound by theory, it is believed that light with wavelengths of approximately 200 nm to approximately 240 nm produced by the deuterium light source 202 has greater spatial irradiance than light of substantially the same wavelength produced by a mercury vapor light source.

[0020] It has been found that the deuterium light source 202 effectively develops deep ultraviolet photoresists, such as PMMA photoresists. This increased efficiency results in reduced exposure time and increased device throughput. In some embodiments, the exposure time for the photoresist is about 10 minutes or less, such as about 8 minutes or less, such as about 6 minutes or less. In some embodiments, compared to other light sources, such as a mercury vapor light source of the same power, the deuterium light source 202 reduces the exposure time for processing the photoresist by about 50% or less, such as about 5% to about 40%, such as about 10% to about 30%, such as about 15% to about 25%.

[0021] The deuterium light source 202 can guide light to the housing 206 via the optical fiber 204. The housing 206 includes a converging lens 208 and an aperture 210 through which light from the deuterium light source 202 is guided. In some embodiments, the converging lens 208 increases the intensity of the light generated by the deuterium light source 202. In some embodiments, the converging lens 208 is a biconvex lens. In some embodiments, the aperture 210 is shaped to enable image bricking and exposure of a photoresist disposed on a substrate 201, which is disposed on a platform 214. In some embodiments, the aperture is shaped like a polygon, such as a square or rectangle (e.g., a slit). In some embodiments, the aperture is sized to expose the entire surface area of ​​the substrate. Alternatively, the aperture is sized to scan a portion of the surface area of ​​the substrate, such as "bricks". As used herein, the term "image bricking" refers to scanning multiple portions of the substrate surface, such as bricks, and piecing the bricks together to form a large image.

[0022] A plurality of pixels are exposed or written together to form a mask pattern. In some embodiments, each deuterium light source 202 has a power of about 50 W or greater, such as from 100 W to about 5,000 W, to increase light intensity. The image projection system 200 allows for easy access to and replacement of the deuterium light source for maintenance purposes. Using a deuterium light source instead of a mercury-based light source provides environmental benefits. It has been found that using a deuterium light source provides cost-effectiveness, longer lifespan, and higher intensity compared to other light sources operating at the same power; and provides lower temperatures at the same power compared to other light sources (e.g., mercury vapor sources). In some embodiments, the deuterium light source operates at temperatures from about 23°C to 100°C, such as from about 50°C to about 80°C.

[0023] Figure 3 is a schematic diagram of an image projection system 300. The system 300 is operable to perform grayscale lithography on a resist to fabricate an optical device. The system 300 includes a deuterium light source array 302 that projects a light beam onto an elliptical reflector 304. The elliptical reflector 304 includes a convex surface and a concave surface. In some embodiments, the concave surface of the elliptical reflector 304 is oriented downward toward the horizontally positioned deuterium light source array 302. In some embodiments, the concave surface of the elliptical reflector 304 is oriented at an angle relative to a horizontal axis, such as from about 5° to about 180°, such as 90° where the elliptical reflector 304 is vertically positioned. The deuterium light source array 302 is similarly oriented at any of the angles described for the elliptical reflector 304 and is generally parallel to the elliptical reflector 304. Each light source of the deuterium light source array 302 increases the intensity of the light projected onto a substrate 301 disposed on a platform 314. In some embodiments, such as when the elliptical reflector 304 is horizontally positioned, the elliptical reflector 304 guides the light beam to the dielectric mirror 306, which focuses the light beam to the optical integrator 308. In some embodiments, the dielectric mirror 306 comprises a metallic material. In some embodiments, the dielectric mirror 306 is made of an oxide-containing material, a silicon-containing material, or a combination thereof. In some embodiments, the dielectric mirror 306 is a Fresnel dielectric mirror. Without being bound by theory, the dielectric mirror 306 is believed to provide uniformity of light guided to the substrate 101. The elliptical reflector 304 includes a convex shape or other shapes. In some embodiments, such as when the elliptical reflector 304 and the deuterium light source array 302 are vertically positioned, the elliptical reflector 304 guides the light beam directly to the optical integrator 308. In some embodiments, the light beam contacts the reflector 310 and is guided to the collimating lens 312. The optical integrator 308 is operable to receive scattered light from the elliptical reflector 304 and combine the light into a single focused beam. In some embodiments, the optical integrator 308 includes a plurality of lenses operable to focus light. In some embodiments, a shield may be positioned between the collimating lens 312 and the platform 314. Alternatively, the system described herein is shieldless. In some embodiments, the reflector 310 is an aluminum reflector. The image projection system 300 allows for easy access to and replacement of the deuterium light source for maintenance purposes.

[0024] Figure 4 is a flowchart illustrating a method 400 of forming an apparatus according to some embodiments. The method includes depositing a resist on a substrate, such as the substrate shown in Figures 1, 2, and 3, at an activity 402. In some embodiments, the resist is deposited on a lower film located below the resist and above the substrate. The lower film may be the uppermost surface of a thin film stack disposed above the substrate.

[0025] In activity 404, an exposure pattern for forming the apparatus is determined. In activity 406, a portion of a resist is exposed with a light beam based on the determined exposure pattern. This portion of the resist includes a light beam guided from a deuterium source, such as the deuterium source shown in Figure 2 or the deuterium source 302 shown in Figure 3. The light beam may have a beam path from the deuterium source 202 (as shown in Figure 2) through the optical fiber 204 to the converging lens 208 in the housing 206. The light beam may be guided along a beam path from the converging lens 208 to the aperture 210 of the housing 206. The light beam may be guided along a beam path from the aperture 210 to a portion of the substrate 101.

[0026] Alternatively, the light beam may have a beam path from the deuterium source 302 to the concave surface of the elliptical reflector 304. In some embodiments, the elliptical reflector 304 may guide the light beam directly along the beam path to the optical integrator 308. In some embodiments, the elliptical reflector 304 may guide the light beam along the beam path to one or more mirrors, such as the dielectric mirror 306 preceding the optical integrator 308. In some embodiments, the light beam may be guided along the beam path from the optical integrator 308 to one or more mirrors, such as mirror 310, like an aluminum mirror. The light beam may be guided from mirror 310 to collimating lens 312. The light beam may be guided from collimating lens to substrate 101.

[0027] In activity 408, a resist having portions exposed to a beam of light from a deuterium light source is developed using a photoresist developer. The exposed portions are soluble in the photoresist developer, such that the developed resist provides a patterned resist on the underlying thin film layer. The method may further include etching portions of the underlying thin film layer via openings in the developed resist.

[0028] The method and system provided herein implement a lithography process using a deuterium light source. Using a deuterium light source instead of other light sources, such as mercury vapor light sources, can provide a more efficient process with a longer lifespan and higher equipment throughput.

[0029] Although the foregoing content is directed to various embodiments of this case, other and further embodiments of this case may be designed without departing from the basic scope of this case, and the scope of this case is determined by the following patent application scope. [Simplified Explanation of the Diagram]

[0008] A more specific description of the present invention, briefly summarized above, can be obtained by referring to the embodiments, some of which are illustrated in the accompanying drawings, in a manner that enables a detailed understanding of the above-described features of the present invention. However, it should be noted that the drawings illustrate exemplary embodiments only and are therefore not intended to limit the scope of the present invention, and other equally effective embodiments are permissible.

[0009] Figure 1 is a schematic diagram of a lithography system according to some embodiments.

[0010] Figure 2 is a schematic diagram of an image projection system according to some embodiments.

[0011] Figure 3 is a schematic diagram of an image projection system according to some embodiments.

[0012] Figure 4 is a flowchart illustrating a method of forming an apparatus according to some embodiments.

[0013] To facilitate understanding, the same element symbols have been used where possible to indicate the same elements shared by the figures. It is contemplated that elements and features of one embodiment may be advantageously incorporated into other embodiments without further description. [Biomaterial Storage]

[0031] Domestic storage information (please note in order of storage institution, date, and number): None. International storage information (please note in order of storage country, institution, date, and number): None.

Claims

1. A lithography system for performing lithography, comprising: a plurality of image projection systems, wherein each image projection system comprises: a deuterium light source; a housing, wherein the housing is directly coupled to the deuterium light source at a first end, the housing having a second end having an opening; a converging lens disposed inside the housing and located in the path of an optical fiber; and an aperture coupled to the second end of the housing, the opening of the housing being located in the path of the converging lens; and a movable platform disposed adjacent to the aperture, wherein the movable platform is configured to move along at least three axes and relative to at least one of the deuterium light source, the converging lens, and the aperture.

2. The lithography system as claimed in claim 1, wherein the converging lens and the aperture are housed within the housing.

3. An image projection system for performing lithography, comprising: a deuterium light source, including an array of deuterium light sources; an elliptical reflector downstream of the deuterium light source along a beam path from the deuterium light source, wherein the array of deuterium light sources is substantially parallel to a major axis of the elliptical reflector; an optical integrator disposed downstream of the elliptical reflector; a mirror disposed immediately downstream of the optical integrator; a collimating lens disposed downstream of the mirror; and a platform disposed downstream of the collimating lens.

4. The image projection system as described in claim 3, wherein the reflector is an aluminum reflector.

5. The image projection system as claimed in claim 3, wherein the elliptical reflector is positioned with a concave surface oriented in a direction about a surface of the platform.

6. The image projection system as claimed in claim 3 further includes a dielectric mirror disposed between the elliptical reflector and the mirror along the beam path.

7. The image projection system as claimed in claim 3, wherein the elliptical reflector is positioned with a concave surface oriented in a direction perpendicular to a surface of the platform.

8. A method of manufacturing an optical device, the method comprising the steps of: using an image projection system to expose a portion of a resist disposed on a substrate with a light beam based on a predetermined exposure pattern, the image projection system comprising: a deuterium light source, including an array of deuterium light sources; an elliptical reflector downstream of the deuterium light source along a light beam path from the deuterium light source, wherein the array of deuterium light sources is substantially parallel to a major axis of the elliptical reflector; an optical integrator disposed downstream of the elliptical reflector; a mirror disposed immediately downstream of the optical integrator; a collimating lens disposed downstream of the mirror; and a platform disposed downstream of the collimating lens, wherein the step of exposing the portion of the resist comprises the steps of: guiding the light beam from the array of deuterium light sources to the platform; and developing the resist.

9. The method as described in claim 8, wherein the inhibitor is composed of poly(methyl methacrylate) (PMMA).

10. The method as described in claim 8, wherein the developing agent exposes portions of the underlying thin film layer.

11. The method as described in claim 10 further comprises the step of etching the underlying thin film layer through an opening in the developer resist.

12. The method as described in claim 8, wherein the deuterium light source operates at a temperature of approximately 23°C to 100°C.

13. The method as described in claim 8, wherein the reflector is an aluminum reflector.

14. The method as described in claim 8, wherein the elliptical reflector is positioned with a concave surface oriented in a direction relative to a surface of the platform.

15. The method as described in claim 8, further comprising a dielectric mirror disposed between the elliptical reflector and the mirror along the beam path.

16. The method as described in claim 8, wherein the elliptical reflector is positioned with a concave surface oriented in a direction perpendicular to a surface of the platform.

17. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause a computer system to perform the method described in claim 8.

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