Exposure method, method of fabricating periodic microstructure, method of fabricating grid polarizing element and exposure apparatus

• US 10,101,652 B2
• Filed: 09/24/2015
• Issued: 10/16/2018
• Est. Priority Date: 09/24/2015
• Status: Active Grant

• Current Assignee: Ushio Denki Kabushiki Kaisha (Ushio Incorporated)
• Original Assignee: Ushio Denki Kabushiki Kaisha (Ushio Incorporated)
• Inventors: Yajima, Daisuke, Nomoto, Kentaro, Nawaki, Yohei
• Primary Examiner(s): Angebranndt, Martin J
• Application Number:
  US15/310,108
• Publication Number:
  US 20170261847A1
• Time in Patent Office: 1,118 Days
• Field of Search: None
• CPC Class Codes: G02B 5/3058 comprising electrically conductive elements, e.g. wire grids, conductive particles
• CPC Class Codes: G02B 5/3075 for use in the UV G02B5/3066 takes precedence
• CPC Class Codes: G03F 7/0005 Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor
• CPC Class Codes: G03F 7/201 characterised by an oblique exposure; characterised by the use of plural sources; characterised by the rotation of the optical device; characterised by a relative movement of the optical device, the light source, the sensitive system or the mask
• CPC Class Codes: G03F 7/203 comprising an imagewise exposure to electromagnetic radiation or corpuscular radiation
• CPC Class Codes: G03F 7/22 Exposing sequentially with the same light pattern different positions of the same surface G03F7/70 takes precedence
• CPC Class Codes: G03F 7/70408 Interferometric lithography; Holographic lithography; Self-imaging lithography, e.g. utilizing the Talbot effect
• CPC Class Codes: G03F 7/70475 Stitching, i.e. connecting image fields to produce a device field, the field occupied by a device such as a memory chip, processor chip, CCD, flat panel display

Abstract

Disclosed herein an exposure apparatus capable of implementing a microfabrication onto a work with a higher throughput and a lower cost. The exposure apparatus generates interfering light by crossing two or more branched light beams branched from output light from a coherent light source at a predetermined interfering angle, and exposes the substrate by repeating an irradiation onto the substrate with the interfering light and a conveyance of the substrate. At this moment, the exposure apparatus shapes in interfering light irradiation region on the substrate onto which the interfering light is irradiated into a predetermined shape. Then, the exposure apparatus disposes a plurality of the interfering light irradiation regions in successive shots to be located adjacent to each other on the substrate in a direction of conveying the substrate without the interfering light irradiation regions being overlapped when exposing the substrate while conveying the substrate in a stepwise manner.

Claims

1. An exposure method, comprising:

generating interfering light by crossing, at a predetermined angle, two or more light beams branched from output light from a coherent light source;

arranging a light shielding member having a light transmissive part of a substantially rectangular shape above a substrate;

irradiating the substrate with the interfering light through the light shielding member to shape, into the substantially rectangular shape, an interfering light irradiation region and to cause, at both sides of the interfering light irradiation region, non-interfering light irradiation regions to be generated, the interfering light irradiation region being a region on the substrate on which the interfering light is irradiated per one shot and interference fringes are formed, each of the non-interfering light irradiation regions being a region where only one of the two or more light beams is incident and the interference fringes are not formed;

conveying, in a stepwise manner, the substrate in a conveying direction; and

repeating said irradiating and said conveying so as to form a plurality of said interfering light irradiation regions each having the non-interfering light irradiation regions at the both sides thereof in the conveying direction;

wherein

the substrate is conveyed such that one of said plurality of said interfering light irradiation regions is positioned without overlapping next one of said plurality of said interfering light irradiation regions and one of the non-interfering light irradiation regions is positioned with overlapping next one of the non-interfering light irradiation regions so as to separate said plurality of said interfering light irradiation regions solely by the overlapped non-interfering light irradiation regions in the conveying direction, and

each of said plurality of interfering light irradiation regions has a Gaussian distribution.

2. The exposure method according to claim 1, further comprising:

forming the non-interfering light irradiation region irradiated with non-interfering light that is a part of the at least two branched light beams at an end of the interfering light irradiation region, by arranging the light shielding member above the substrate with a predetermined gap being provided; and

disposing a plurality of the non-interfering light irradiation regions that are formed at ends of the neighboring interfering light irradiation regions in the direction of conveying the substrate to be overlapped, when the substrate is exposed while being conveyed in the stepwise manner.

3. The exposure method according to claim 1, further comprising:

forming the non-interfering light irradiation region irradiated with non-interfering light, which is a part of the at least two branched light beams at an end of the interfering light irradiation region, by arranging the light shielding member above the substrate with a predetermined gap being provided; and

disposing the interfering light irradiation region to be overlapped with the non-interfering light irradiation regions that is formed at the end of a neighboring interfering light irradiation region in the direction of conveying the substrate, when the substrate is exposed while being conveyed in the stepwise manner.

4. The exposure method according to claim 1, wherein the light shielding member is arranged directly on the substrate.

5. A method for fabricating a periodic microstructure, comprising:

exposing the substrate by use of the exposure method according to claim 1; and

imparting a physical property corresponding to the interference fringe or forming a pattern corresponding to the interference fringe onto the substrate.

6. A method for fabricating a periodic microstructure, comprising:

a step of exposing the substrate by use of the exposure method according to claim 1; and

a step of developing the substrate after being exposed and forming a pattern corresponding to the interference fringe onto the substrate.

7. A method for fabricating a grid polarizing element, comprising:

a step of forming an inorganic dielectric layer composed of an inorganic dielectric body on a transparent substrate;

a step of forming a photosensitive layer composed of a photosensitive material on the inorganic dielectric layer;

a step of exposing the photosensitive layer by use of the exposure method according to claim 1;

a step of developing the photosensitive layer after being exposed and forming a pattern corresponding to the interference fringe onto the photosensitive layer; and

a step of removing the inorganic dielectric layer by an etching based on the pattern formed on the photosensitive layer and forming a grid layer composed of the inorganic dielectric body, the grid layer having a periodic microstructure.

8. The method for fabricating a grid polarizing element according to claim 7, wherein, in the step of exposing, the photosensitive layer is exposed such that a proportion of an area of a non-interfering light irradiation region with respect to an area of the interfering light irradiation region is less than 0.4%.

9. An exposure apparatus, comprising:

a light source configured to emit coherent light;

an optical system configured to cross two or more light beams at a predetermined interference angle to generate interfering light, the two or more light beams being branched from output light from the light source;

a light shielding member arranged above the substrate and configured to have a light transmissive part of a substantially rectangular shape through which the interfering light generated by the optical system transmits; and

a substrate conveyance controlling unit configured to convey the substrate in a conveying direction and to repeat an irradiation onto the substrate with the interfering light and a conveyance of the substrate, and to expose the substrate, wherein

the optical system irradiates the substrate with the interfering light through the light shielding member to shape, into the substantially rectangular shape, an interfering light irradiation region and to cause, at both sides of the interfering light irradiation region, non-interfering light irradiation regions to be generated, the interfering light irradiation region being a region on the substrate on which the interfering light is irradiated per one shot and interference fringes are formed, each of the non-interfering light irradiation regions being a region where only one of the two or more light beams is incident and the interference fringes are not formed,

a plurality of said interfering light irradiation regions each having the non-interfering light irradiation regions at the both sides thereof are formed in the conveying direction,

the substrate conveyance controlling unit conveys, in a stepwise manner, the substrate such that one of said plurality of interfering light irradiation regions is positioned without overlapping next one of said plurality of said interfering light irradiation regions and one of the non-interfering light irradiation regions is positioned with overlapping next one of the non-interfering light irradiation regions so as to separate said plurality of said interfering light irradiation regions solely by the overlapped noninterfering light irradiation regions in the conveying direction, and

each of said plurality of interfering light irradiation regions has a Gaussian distribution.

10. The exposure apparatus according to claim 9, wherein the optical system includes:

a light branching element configured to branch the output light from the light source into two or more light beams; and

angle variable mirrors configured to deflect the respective branched two or more light beams towards the substrate, respectively, so as to cross the branched two or more light beams branched each other by the light branching element at a desired interference angle.