Optical system and method for illuimination of reflective spatial light modulators in maskless lithography

• US 20080198354A1
• Filed: 02/20/2007
• Published: 08/21/2008
• Est. Priority Date: 02/20/2007
• Status: Active Grant

• Current Assignee: ASML Holding NV
• Original Assignee: ASML Holding NV
• Inventors: Sobolev, Kirill Y., Smirnov, Stanislav Y.
• Granted Patent: US 7,965,378 B2
• Time in Patent Office: Days
• US Class Current: 355/67
• CPC Class Codes: G03F 7/70066 Size and form of the illuminated area in the mask plane, e.g. reticle masking blades or blinds
• CPC Class Codes: G03F 7/702 Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems
• 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

An illuminator for a lithography system is provided. The illuminator includes a mask positioned along an optical axis and first and second refractive groupings positioned along the axis in cooperative arrangement with the mask. Also included are first and second reflecting devices for reflecting an image output from the first and second refractive groupings and a spatial light modulator (SLM) positioned along the axis in cooperative arrangement with the first and second reflecting devices. The active areas of the mask and the SLM are positioned off-axis.

Claims

1. An illuminator for a maskless lithography system, comprising:

a mask positioned along an optical axis;

first and second refractive groupings positioned along the axis in cooperative arrangement with the mask;

first and second reflecting devices for reflecting an image output from the first and second refractive groupings; and

a spatial light modulator (SLM) positioned along the axis in cooperative arrangement with the first and second reflecting devices;

wherein active areas of the mask and the SLM are positioned off-axis.

2. The illuminator of claim 1, wherein the first refractive grouping includes first and second lens groups having a first intermediate pupil positioned therebetween.

3. The illuminator of claim 1, wherein the first reflecting device is at least one from the group including concave, flat, and convex mirrors.

4. The illuminator of claim 1, wherein the second reflecting device is a concave mirror.

5. The illuminator of claim 1, wherein the SLM is reflective.

6. The illuminator of claim 1, further comprising a third reflecting device positioned between the first and second refractive groupings.

7. The illuminator of claim 6, wherein the third reflecting device is a folding mirror.

8. The illuminator of claim 1, wherein the SLM is illuminated non-telecentrically.

9. The illuminator of claim 1, wherein the second reflecting device is ellipsoidal mirror.

10. A lithography system, comprising:

an illuminator including;

a mask positioned along an optical axis;

first and second refractive groupings positioned along an axis in cooperative arrangement with the mask;

first and second reflecting devices for reflecting an image output from the first and second refractive groupings; and

a spatial light modulator (SLM) positioned along the axis in cooperative arrangement with the first and second reflecting devices;

wherein active areas of the mask and the SLM are positioned off-axis; and

projection optics including an entrance pupil;

wherein the projection optics and the illuminator share a common optical axis.

11. The lithography system of claim 10, wherein the second reflecting device is a concave mirror.

12. The lithography system of claim 10, wherein the lithography system is devoid of a beam splitting mechanism.

13. The lithography system of claim 10, wherein the SLM is reflective.

14. The lithography system of claim 10, further comprising a third reflecting device positioned between the first and second refractive groupings.