Illumination system with flat 1D-patterned mask for use in EUV-exposure tool

Patent metadata

Field	Value
Publication number	US-11054745-B2
Application number	US-201916664478-A
Country	US
Kind code	B2
Filing date	Oct 25, 2019
Priority date	Apr 26, 2017
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

A catoptric system having a reference axis and including a reflective pattern-source (carrying a substantially one-dimensional pattern) and a combination of only three optical components disposed sequentially to transfer EUV radiation incident the first optical component onto the pattern-source. The combination is disposed in a fixed spatial and optical relationship with respect to the pattern-source, and represents an illumination unit (IU) of a 1D EUV exposure tool that additionally includes a projection optic sub-system configured to form an optical image of the pattern-source on an image plane with the use of only two beams of radiation. These only two beams of radiation originate at the pattern-source from the EUV radiation transferred onto the pattern-source.

First claim

What is claimed is:

1. A catoptric system for use with a reflective pattern-source carrying a substantially one-dimensional pattern thereon, the system comprising:
illumination mirrors disposed between an EUV radiation source and the reflective pattern-source, the illumination mirrors situated to direct EUV radiation from the EUV radiation source to the reflective pattern-source; and
projection mirrors disposed between the reflective pattern-source and a workpiece, the projection mirrors situated to direct diffracted beams caused by irradiating the reflective pattern-source with the EUV radiation to the workpiece,
wherein a last mirror closest to the reflection pattern-source among the illumination mirrors has a first dimension along a period direction of the substantially one-dimensional pattern and a second dimension along a direction that is perpendicular to the period direction, wherein the second dimension is greater than the first dimension.

2. The catoptric system of claim 1 , wherein the last mirror is disposed between the reflective pattern-source and the workpiece.

3. The catoptric system of claim 2 , wherein the last mirror is disposed between optical paths of the diffracted beams.

4. The catoptric system of claim 3 , wherein the projection mirrors define a projection optical axis, and wherein the last mirror is disposed on the projection optical axis.

5. The catoptric system of claim 1 , wherein the last mirror has convex sides.

6. The catoptric system of claim 1 , wherein the last mirror has a leaf shape.

7. The catoptric system of claim 1 , wherein radiation from the last mirror is incident perpendicularly to the reflective pattern-source.

8. The catoptric system of claim 1 , wherein the last mirror includes a mirror array.

9. The catoptric system of claim 8 , wherein the projection mirrors constitute projection optics, and wherein an entrance pupil of the projection optics corresponds to the last mirror.

10. The catoptric system of claim 1 , wherein the projection mirrors are situated to form a fringe pattern.

11. A lithographic exposure tool, comprising:
the catoptric system of claim 10 ; and
workpiece stage configured to retain the workpiece and move the workpiece along a scanning direction.

12. The lithographic exposure tool of claim 11 , wherein the scanning direction is perpendicular to the period direction of the fringe pattern.

13. The lithographic exposure tool of claim 12 , wherein the fringe pattern is spatially fixed with respect to the projection mirrors.

14. The lithographic exposure tool of claim 13 , wherein the workpiece is configured to be movable with respect to the spatially fixed fringe pattern.

15. The lithographic exposure tool of claim 11 , wherein the fringe pattern is formed at a location that is optically conjugate point to the reflective pattern-source.

16. The lithographic exposure tool of claim 11 , wherein the reflective pattern-source is configured to remain spatially fixed while the workpiece stage moves.

17. A method for forming a fringe pattern onto a workpiece, the method comprising:
generating EUV radiation;
directing the EUV radiation to a reflective pattern-source defining a one-dimensional pattern via illumination mirrors;
directing diffracted beams from the reflective pattern-source to the workpiece in response to the EUV radiation directed to the reflective pattern-source; and
forming the fringe pattern with the diffracted beams,
wherein a last mirror closest to the reflective pattern-source among the illumination mirrors has a first dimension along a period direction of the one-dimensional pattern and a second dimension along a direction perpendicular to the period direction, wherein the first dimension is less than the second dimension.

18. A microdevice manufacturing method, comprising:
preparing a workpiece;
forming a fringe pattern on a surface of the workpiece using the method of claim 17 ; and
processing the workpiece.

Assignees

• Nikon Corp

Inventors

• Smith Daniel Gene
• Williamson David M

Classifications

• G02B17/0848

  off-axis or unobscured systems in which not all of the mirrors share a common axis of rotational symmetry, e.g. at least one of the mirrors is warped, tilted or decentered with respect to the other elements · CPC title

• G03F7/2008 Primary

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

• G02B17/0892 Primary

  specially adapted for the UV · CPC title

• G03F7/2004

  characterised by the use of a particular light source, e.g. fluorescent lamps or deep UV light · CPC title

• G02B17/0626

  using three curved mirrors (G02B17/0668, G02B17/0694 take precedence) · CPC title