Systems and methods that utilize angled photolithography for manufacturing light guide elements

Patent metadata

Field	Value
Publication number	US-11994802-B2
Application number	US-202117464185-A
Country	US
Kind code	B2
Filing date	Sep 1, 2021
Priority date	Nov 7, 2018
Publication date	May 28, 2024
Grant date	May 28, 2024

Abstract

Systems and methods described herein relate to the manufacture of optical elements and optical systems. An example system may include an optical component configured to direct light from a light source to illuminate a photoresist material at a desired angle and to expose at least a portion of an angled structure in the photoresist material, where the photoresist material overlays at least a portion of a top surface of a substrate. The optical component includes a container containing an light-coupling material that is selected based in part on the desired angle. The optical component also includes a mirror arranged to reflect at least a portion of the light to illuminate the photoresist material at the desired angle.

First claim

We claim:

1. A system comprising:
an optical assembly configured to direct light emitted by a light source to illuminate a photoresist material at a desired angle and to expose an angled structure in the photoresist material, wherein the photoresist material overlays at least a portion of a top surface of a substrate disposed on a wafer, and wherein the optical assembly comprises:
a container containing a light-coupling liquid that is selected based in part on the desired angle;
a mirror arranged to reflect at least a first portion of the emitted light to illuminate the photoresist material at the desired angle; and
a bar positioned over a center of a first mask where the bar is positioned near the center of the optical assembly, wherein there is some separation between the bar and the photoresist material, and wherein the bar is configured to cast a shadow down a center of the wafer that shields the center of the wafer from light exposures at two different non-normal angles or overlapping exposures.

2. The system of claim 1 , further comprising the first mask placed between the light source and the substrate, wherein the first mask comprises one or more openings, each opening corresponding to a respective desired structure in the photoresist material, and wherein at least a portion of the emitted light that shines through each opening exposes the respective desired structure to which the opening corresponds.

3. The system of claim 2 , wherein the respective desired structure is one of a vertical structure and an angled structure, and wherein a first opening that corresponds to the angle structure directs the first portion of the emitted light to the mirror.

4. The system of claim 2 , wherein the optical assembly is further configured to direct the emitted light from the light source to illuminate the photoresist material at a substantially normal angle and to expose a vertical structure in the photoresist material, and wherein a first opening that corresponds to the vertical structure directs a second portion of the emitted light to the photoresist material.

5. The system of claim 1 , wherein an exit surface of the container comprises one or more fiducials usable to align the container with the substrate.

6. The system of claim 1 , wherein at least a portion of a top surface and at least a portion of a bottom surface of the container are transparent, wherein the emitted light enters the container through the transparent portion of the top surface, and wherein the emitted light illuminates the photoresist material through the transparent portion of the bottom surface.

7. The system of claim 1 , further comprising a second mask arranged in proximity of the photoresist material, wherein the second mask is configured to define individual desired structures in the photoresist material.

8. The system of claim 1 , further comprising a second mask fabricated on the top surface of the substrate, wherein the photoresist material overlays the second mask, and wherein the emitted light illuminates the photoresist material through a bottom surface of the substrate.

9. The system of claim 1 , wherein the light source comprises a polarization filter, wherein the emitted light is p-polarized light, and wherein the p-polarized light reduces light reflections from at least one of: (i) an interface between the substrate and the photoresist material, and (ii) a bottom surface of the substrate.

10. The system of claim 1 , wherein the optical assembly further comprises one or more dark baffles configured to remove light reflected back into the optical assembly.

11. The system of claim 1 , wherein the optical assembly further comprises plumbing fittings for filling or draining the light-coupling liquid from the container.

12. The system of claim 1 , wherein the optical assembly further comprises a second mirror arranged to reflect at least a second portion of the light to illuminate the photoresist material at a second desired angle.

13. The system of claim 1 , wherein an exterior of the container comprises one or more fittings for components that are configured to remove air bubbles from the container.

14. The system of claim 1 , wherein the substrate is immersed in the light-coupling material such that the photoresist liquid is facing a bottom surface of the container, wherein at least a portion of the bottom surface of the container is transparent, and wherein the emitted light from the light source enters the container through the transparent portion of the bottom surface of the container.

15. A method comprising:
placing a substrate disposed on a wafer near one end of an optical assembly, wherein a photoresist material overlays at least a portion of a top surface of the substrate, and wherein the optical assembly comprises:
(i) a container containing an light-coupling liquid that is selected based in part on a desired angle of incidence;
(ii) a mirror; and
(iii) a bar positioned over a center of a first mask where the bar is positioned near the center of the optical assembly, wherein there is some separation between the bar and the photoresist material, and wherein the bar is configured to cast a shadow down a center of the wafer that shields the center of the wafer from light exposures at two different non-normal angles or overlapping exposures; and
causing a light source to emit light into the optical assembly, wherein the mirror reflects at least a portion of the emitted light to illuminate the photoresist material at the desired angle of incidence, thereby exposing at least a portion of an angled structure in the photoresist material.

16. The method of claim 15 , further comprising:
based on the desired angle of incidence, determining an orientation angle for the mirror; and
causing the mirror to be oriented at the orientation angle.

17. The method of claim 15 , wherein the method further comprises:
overlaying the first mask near a surface of the optical assembly, wherein the first mask comprises one or more openings, each opening corresponding to a respective desired structure in the photoresist material, and wherein at least a portion of the emitted light that shines through each opening exposes the respective desired structure to which the opening corresponds.

18. The method of claim 15 , wherein the method further comprises:
overlaying a second mask in proximity of the photoresist material, wherein the second mask is configured to define individual desired structures in the photoresist material.

19. The method of claim 15 , further comprising:
developing the photoresist material so as to retain an elongate portion of the photoresist material on the substrate, wherein a first end of the elongate portion comprises the angled structure, and wherein the angled structure is sloped at an angle with respect to respect to the top surface of the substrate.

20. A method of fabricating an optical element, comprising the steps of:
placing a substrate disposed on a wafer near one end of an optical assembly, wherein photoresist material overlays at least a portion of a top surface of the substrate, and wherein the optical assembly comprises:
(i) a container containing an light-coupling liquid;
(ii) a mirror;
(iii) a bar positioned over a center of a first mask where the bar is positioned near the center of the optical assembly, wherein there is some separation between the bar and the photoresist material, and wherein the bar is configured to cast a shadow down a center of the wafer that shields the center of the wafer from ligh

Assignees

• Waymo Llc

Inventors

• Dunphy James
• Hutchison David

Classifications

• H10P76/00

  Manufacture or treatment of masks on semiconductor bodies, e.g. by lithography or photolithography · CPC title

• G03F7/201 Primary

  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 title

• G03F7/0005

  Production of optical devices or components in so far as characterised by the lithographic processes or materials used therefor · CPC title

• G03F7/2008

  characterised by the reflectors, diffusers, light or heat filtering means or anti-reflective means used · CPC title

• G03F7/2014

  Contact or film exposure of light sensitive plates such as lithographic plates or circuit boards, e.g. in a vacuum frame · CPC title