Method and apparatus for maskless photolithography

• US 7,573,561 B2
• Filed: 06/15/2007
• Issued: 08/11/2009
• Est. Priority Date: 06/27/2001
• Status: Expired due to Term

• Current Assignee: University of South Florida (State University System of Florida)
• Original Assignee: University of South Florida (State University System of Florida)
• Inventors: Fries, David P.
• Primary Examiner(s): FULLER, RODNEY EVAN
• Application Number:
  US11/818,930
• Publication Number:
  US 20070296946A1
• Time in Patent Office: 788 Days
• Field of Search: 355/53, 355/67, 355/71, 355/72, 355/75, 355/77, 430/5, 430/22, 430/30, 430/296, 430/396, 250/492.2
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70291 Addressable masks, e.g. spatial light modulators [SLMs], digital micro-mirror devices [DMDs] or liquid crystal display [LCD] patterning devices

Abstract

A method and apparatus to create two dimensional and three dimensional structures using a maskless photolithography system is provided. In an embodiment, the pattern generator comprises a micromirror array wherein the positioning of the mirrors in the micromirror array and the time duration of exposure can be modulated to produce patterns to photoform photosensitive material. The desired pattern can be designed and stored using conventional computer aided drawing techniques and can be used to control the positioning of the individual mirrors in the micromirror array to reflect the corresponding desired pattern. A fixture for mounting of the substrate can be incorporated and can allow the substrate to be moved three dimensions. The fixture can be rotated in one, two, or three directions.

Claims

1. A maskless photolithography system for large area photoforming of photosensitive materials comprising:

a. a computer system for generating mask patterns and alignment instructions;

b. a maskless patterned light generator, operably connected to said computer system, for receiving said mask patterns and alignment instructions, radiating a patterned light beam directed at the photosensitive material, wherein said patterned light beam is generated in conjunction with said alignment instructions; and

c. a movable mount to provide relative movement of said maskless patterned light generator and the photosensitive material exposed to said patterned light,

wherein the pattern of said patterned light beam is generated in conjunction with the relative movement of said maskless patterned light generator and the photosensitive material to provide large area photoforming of the photosensitive material, wherein the movable mount is an automatically controlled alignment mount, wherein the alignment mount is movable in coplanar first and second dimensions, and in a third dimension direction substantially perpendicular to the first and second coplanar dimensions and substantially parallel to the patterned light beam;

the mount providing three dimensional alignment, wherein the alignment mount is moved in three dimensions in response to alignments instruction provided by the computer system.

2. The system of claim 1, wherein said relative movement is provided by mounting said maskless photolithography system on said movable mount and moving said mount in relation to the photosensitive material.

3. The system of claim 1, wherein said relative movement is provided by mounting the photosensitive material on said movable mount and moving said mount in relation to said maskless photolithography system.

4. The system according to claim 1,

wherein the moveable mount is automatically controlled.

5. The system of claim 1, wherein said maskless patterned light generator comprises:

a. an array of positionable micromirrors, wherein said micromirrors reflect light according to said mask patterns provided by said computer system;

b. an optical system for generating, collimating, and directing the light beam to said micromirror array; and

c. an optical system for further collimating the light beam reflected from said mirrors and directing said patterned light beam onto the photosensitive material and to create patterns on the photosensitive material corresponding to said mask patterns.

6. The system of claim 1, wherein said maskless patterned light generator comprises a plasma display having individually addressable pixels, operably connected to and controllable by said computer system, wherein said display generates said patterned light beam corresponding to said mask patterns provided by said computer system to expose the photosensitive material to said patterned light beam and to create patterns on the photosensitive material corresponding to said mask patterns.

7. The system of claim 1, wherein said maskless patterned light generator comprises a liquid crystal display having individually addressable pixels, operably connected to and controllable by said computer system, wherein said pixels are addressed to transmit or block light corresponding to said mask patterns provided by said computer system to provide a patterned light beam to expose the photosensitive material and create patterns on the photosensitive material corresponding to said mask patterns.

8. The system of claim 1, wherein said movable mount is a manually controlled alignment mount, wherein said alignment mount is movable in coplanar first and second dimensions, and in a third dimension direction substantially perpendicular to said first and second coplanar dimensions and substantially parallel to said patterned light beam;

said mount providing three dimensional alignment, wherein said alignment mount is moved in three dimensions in response to mechanical alignments directly provided by a user.

9. The system of claim 1, further comprising a computer controlled pattern alignment system, for providing electrical alignment of said patterns in coplanar first and second dimensions, wherein said pattern alignment system adjusts the alignment of said mask patterns in coplanar first and second dimensions in response to instructions provided by said computer according to said alignment information, so that said pattern is shifted in at least one coplanar direction.

10. The system of claim 1, further comprising an optical viewer to allow optical monitoring of positioning of the immersed substrate mounted in said alignment fixture by visually verifying that an image projected on the immersed substrate is properly aligned.

11. The system of claim 10, wherein the optical viewer comprises a device selected from the group consisting of:

a camera, a vision system, and a microscope.

12. The system of claim 1, further comprising an optical filter, removably mounted in the light beam to selectively filter light impinging on the immersed substrate to prevent exposure of the immersed substrate during an alignment procedure.

13. A maskless photolithography method for large area photoforming of photosensitive materials comprising:

a. receiving mask pattern information and alignment information corresponding to a desired pattern to be created on the photosensitive material;

b. generating mask patterns based on received mask pattern information and alignment information;

c. providing said mask patterns to a patterned light generator;

d. generating a patterned light beam;

e. directing said patterned light beam onto a first exposure area of the photosensitive material;

f. exposing the first exposure area of the photosensitive material to said patterned light beam;

g. providing relative movement of the photosensitive material and the maskless photolithography system to allow exposure of a second exposure area; and

h. repeating steps a-g to sequentially expose the entire surface of the photosensitive material;

wherein said patterned light beam incident on the photosensitive material photosculpts the photosensitive material to create contiguous patterns by sequential exposure corresponding to said patterned light beam, wherein providing relative movement of the photosensitive material and the maskless photolithography system to allow exposure of a second exposure area comprises providing relative movement of the photosensitive material and the maskless photolithography system in coplanar first and second dimensions and providing relative movement of the photosensitive material and the maskless photolithography system in a third dimension direction substantially perpendicular to the first and second coplanar dimensions, and substantially parallel to the patterned light beam.

14. The method of claim 13, wherein generating said patterned light beam further comprises:

a. receiving said mask patterns at an array of positionable micromirrors;

b. generating, collimating, and directing a light beam to said micromirror array;

c. positioning said micromirrors to reflect the light beam from said micromirror array according to said mask patterns; and

d. collimating said patterned light beam reflected from said micromirror array.

15. The method of claim 13, wherein generating said patterned light beam further comprises:

a. receiving mask patterns at a plasma display, having individually addressable pixels, operably connected to and controllable by said computer system,

b. activating the pixels of said plasma display to generate a patterned light beam corresponding to said mask patterns provided by said computer system; and

c. collimating said patterned light beam generated by said plasma display.

16. The method of claim 13, further comprising:

a. providing selective filtering of said patterned light beam impinging on the photosensitive material to prevent exposure of an area of the photosensitive material during an alignment procedure;

b. allowing manual alignment of the photosensitive material under said patterned light beam by moving said mounted photosensitive material in three dimensions, wherein the photosensitive material is moved in coplanar first and second dimensions, and moved in a third dimension direction substantially perpendicular to said first and second coplanar dimensions, and substantially parallel to the patterned light beam;

c. allowing optical monitoring of positioning of an area of the photosensitive material under the patterned light beam to visually verify that an image projected on the photosensitive material is properly aligned;

d. receiving alignment information corresponding to alignment of a desired mask pattern projected onto an area of the photosensitive material;

e. generating alignment instructions based on received said alignment information;

f. providing alignment instructions, based on said alignment information, to said patterned light generator to further align said mask patterns in the coplanar first and second dimensions;

g. adjusting said micromirror array according to said alignment instructions by shifting the mask pattern in at least one of the coplanar first and second dimensions;

h. disabling filtering of said patterned light beam;

i. exposing the photosensitive material; and

j. repeating steps (a-i) to create a desired pattern on the photosensitive material.

17. The method of claim 16, wherein allowing optical monitoring of positioning of an area of the photosensitive material is accomplished via an optical viewer comprising a device selected from the group consisting of:

a camera, a vision system, and a microscope.