Maskless optical writer

• US 7,012,674 B2
• Filed: 01/13/2004
• Issued: 03/14/2006
• Est. Priority Date: 01/13/2004
• Status: Active Grant

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Sewell, Harry
• Primary Examiner(s): Nguyen, Henry Hung
• Application Number:
  US10/755,470
• Publication Number:
  US 20050151953A1
• Time in Patent Office: 791 Days
• Field of Search: 355/53, 355 67- 71, 430/5, 430/20, 430/30, 359/290, 359/245
• US Class Current: 355/67
• CPC Class Codes: A61B 6/4435 the source unit and the detector unit being coupled by a rigid structure
• CPC Class Codes: G03F 7/70283 Mask effects on the imaging process
• 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
• CPC Class Codes: G03F 7/70566 Polarisation control

Abstract

A maskless pattern generating system for use in lithography includes a light source that generates a light beam, a programmable pattern generator that generates a pattern image from the light beam based on a control signal input, and a controller to provide the control signal input to the programmable pattern generator based on pattern information provided to the controller. The control signal input instructs the programmable pattern generator to set individual voltage levels corresponding to individual pixels in a pixel array, wherein each of the individual voltage levels corresponds to a greyscale level assigned to a particular individual pixel. Setting the individual voltage levels provide a phase shift of the resulting pattern image beam, allowing the programmable pattern generator to act as a phase shift mask. This maskless pattern writing system acts as a light valve to control pattern imagery, on a pixel by pixel basis, for the purposes of direct writing patterns.

Claims

1. A maskless pattern generating system for use in a lithographic processing system comprising:

a light source that generates a light beam;

a liquid crystal programmable pattern generator that generates a pattern image from said light beam based on a control signal input instructing said liquid crystal programmable pattern generator to set individual voltage levels corresponding to individual pixels in a pixel array, wherein each of said individual voltage levels corresponds to a greyscale level assigned to a particular one of said individual pixels, wherein a polarization state of said light beam is modulated at each pixel according to each pixel'"'"'s corresponding individual voltage level, and wherein the modulated polarization state of said light beam at each pixel determines an intensity of light output from each pixel and determines whether the light output from each pixel continues through the lithographic processing system; and

a controller that provides said control signal input to said liquid crystal programmable pattern generator based on pattern information provided to said controller.

2. The maskless pattern generating system of claim 1, wherein said liquid crystal programmable pattern generator comprises a reflective liquid crystal display array.

3. The maskless pattern generating system of claim 1, wherein said liquid crystal programmable pattern generator comprises a transmissive liquid crystal display array.

4. The maskless pattern generating system of claim 1, wherein said light beam generated from said light source is a polarized light beam.

5. The maskless pattern generating system of claim 1, further comprising:

a beam splitter that reflects said light beam toward said liquid crystal programmable pattern generator.

6. The maskless pattern generating system of claim 5, wherein said beam splitter is a polarizing beam splitter that polarizes said light beam, reflecting a polarized light beam toward said liquid crystal programmable pattern generator.

7. The maskless pattern generating system of claim 6, wherein said liquid crystal programmable pattern generator modulates a polarization state of said polarized light beam and reflects a pattern image beam back toward said polarizing beam splitter such that said pattern image beam passes through said polarizing beam splitter.

8. The maskless pattern generating system of claim 1, further comprising:

a first polarizer located between said light source and said liquid crystal programmable pattern generator; and

polarizer located after said liquid crystal programmable pattern generator.

9. The maskless pattern generating system of claim 1, further comprising:

reduction optics that minimizes said pattern image for projection onto a substrate; and

a substrate stage that positions said substrate relative to said reduction optics to receive said pattern image.

10. The maskless pattern generating system of claim 9, wherein a pixel size on said substrate ranges from approximately 20 nm to approximately 1.5 mm.

11. The maskless pattern generating system of claim 10, wherein a pixel size on said substrate is approximately 50 nm.

12. The maskless pattern generating system of claim 9, wherein said reduction optics minimizes said pattern image by a magnification range of approximately 0.005×

to 350×

.

13. The maskless pattern generating system of claim 12, wherein said reduction optics minimizes said pattern image by a magnification of approximately 200×

.

14. The maskless pattern generating system of claim 1, wherein said liquid crystal programmable pattern generator covers a slit area ranging from approximately 4 mm by 12 mm to approximately 16 mm by 48 mm.

15. The maskless pattern generating system of claim 14, wherein said liquid crystal programmable pattern generator covers a slit area of approximately 8 mm by 22 mm.

16. The maskless pattern generating system of claim 1, wherein said greyscale level includes black and white.

17. The maskless pattern generating system of claim 1, wherein said light source comprises a pulsed excimer laser whereby said individual voltage levels of said individual pixels are changed between laser pulses.

18. The maskless pattern generating system of claim 1, wherein said pattern image becomes phase-shifted when said individual voltage levels are set past one cycle of light for said individual pixels.

19. The maskless pattern generating system of claim 1, wherein said liquid crystal programmable pattern generator is used as a phase shift mask.

20. The maskless pattern generating system of claim 1, wherein placement of said pattern image is shifted when said individual voltage levels set for said individual pixels corresponding to said pattern image are shifted in one direction by the same number of pixel rows.

21. The maskless pattern generating system of claim 1, wherein an edge of said pattern image is manipulated by setting said individual voltage levels corresponding to said individual pixels that are one of:

part of said pattern image edge; and

a pixel row beyond said individual pixels of said pattern image edge.

22. A method of generating a maskless pattern for use in a lithographic processing system, comprising:

generating a light beam;

receiving a control signal input from a controller based on pattern information provided to the controller; and

generating a pattern image from the light beam based on the control signal input, wherein the control signal input is an instruction to set individual voltage levels corresponding to individual pixels in a liquid crystal pixel array, wherein each of the individual voltage levels corresponds to a greyscale level assigned to a particular one of the individual pixels, wherein a polarization state of the light beam is modulated at each pixel according to each pixel'"'"'s corresponding individual voltage level, and wherein the modulated polarization state of the light beam at each pixel determines an intensity of light output from each pixel and determines whether the light output from each pixel continues through the lithographic processing system.

23. The method of generating a maskless pattern of claim 22, wherein said generating a light beam step comprises:

originating the light beam; and

reflecting the light beam toward a pattern generator.

24. The method of generating a maskless pattern of claim 22, wherein said generating a light beam step comprises:

originating the light beam; and

polarizing the light beam.

25. The method of generating a maskless pattern of claim 22, wherein said generating a pattern image step includes:

polarizing the pattern image.