Reflective lithography masks and systems and methods

Patent metadata

Field	Value
Publication number	US-9599888-B2
Application number	US-201615014699-A
Country	US
Kind code	B2
Filing date	Feb 3, 2016
Priority date	Mar 15, 2012
Publication date	Mar 21, 2017
Grant date	Mar 21, 2017

Abstract

Various non-planar reflective lithography masks, systems using such lithography masks, and methods are disclosed. An embodiment is a lithography mask comprising a transparent substrate, a reflective material, and a reticle pattern. The transparent substrate comprises a curved surface. The reflective material adjoins the curved surface of the transparent substrate, and an interface between the reflective material and the transparent substrate is a reflective surface. The reticle pattern is on a second surface of the transparent substrate. A reflectivity of the reticle pattern is less than a reflectivity of the reflective material. Methods for forming similar lithography masks and for using similar lithography masks are disclosed.

First claim

What is claimed is:

1. A method of forming a photomask, the method comprising:
forming a first reflective material on a convex surface of a transparent substrate;
forming a patterned mask layer on a concave surface of the transparent substrate, the patterned mask layer having openings;
forming a reticle pattern within the openings of the patterned mask layer, the reticle pattern comprising a second reflective material; and
removing the patterned mask layer.

2. The method of claim 1 , wherein the first reflective material is more reflective than the second reflective material.

3. The method of claim 2 , wherein the second reflective material comprises silver emulsion, chromium, iron oxide, or aluminum.

4. The method of claim 1 , wherein the first reflective material comprises tin(II) chloride, silver, aluminum, or copper.

5. The method of claim 1 , wherein forming the reticle pattern is performed at least in part using thermal expansion.

6. The method of claim 1 , wherein the patterned mask layer comprises a patterned photoresist layer.

7. A method of forming a photomask, the method comprising:
attaching a curved substrate to a first handle substrate, the curved substrate having a first curved surface and a second curved surface opposite the first curved surface, the first curved surface facing the first handle substrate;
forming a first reflective material on the second curved surface of the curved substrate;
removing the curved substrate from the first handle substrate;
attaching the curved substrate to a second handle substrate, the second curved surface facing the second handle substrate; and
forming a patterned reflective layer on the first curved surface, the patterned reflective layer comprising a second reflective material.

8. The method of claim 7 , wherein forming the patterned reflective layer comprises:
forming a first patterned mask on the first curved surface, the first patterned mask having openings;
forming a second reflective material in the openings of the first patterned mask; and
removing the first patterned mask, wherein remaining portions of the second reflective material form the patterned reflective layer.

9. The method of claim 8 , wherein forming the first patterned mask comprises:
forming a photoresist layer on the first curved surface; and
patterning the photoresist layer to form the first patterned mask.

10. The method of claim 7 , wherein the first curved surface is a concave surface.

11. The method of claim 7 , wherein the curved substrate comprises a transparent substrate.

12. The method of claim 7 , wherein forming the patterned reflective layer is performed at least in part using thermal expansion.

13. The method of claim 7 , wherein the second reflective material is less reflective than the first reflective material.

14. A method of forming a photomask, the method comprising:
attaching a curved substrate to a first handle substrate, the curved substrate having a first curved surface and a second curved surface opposite the first curved surface;
forming a first patterned mask on the first curved surface, the first patterned mask having openings;
forming a first reflective material in the openings of the first patterned mask; and
removing the first patterned mask.

15. The method of claim 14 , wherein the first curved surface is a concave surface.

16. The method of claim 14 , further comprising forming a second reflective material on the second curved surface.

17. The method of claim 16 , wherein the second reflective material is more reflective than the first reflective material.

18. The method of claim 16 , wherein forming the second reflective material is performed prior to forming the first reflective material.

19. The method of claim 16 , wherein the second reflective material comprises silver emulsion, chromium, iron oxide, or aluminum.

20. The method of claim 14 , wherein forming the first patterned mask comprises depositing a photoresist layer and patterning the photoresist layer.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Liu Chien-Hsuan
• Wang Jen-Pan

Classifications

• G03F7/703

  Non-planar pattern areas or non-planar masks, e.g. curved masks or substrates · CPC title

• G03F1/52 Primary

  Reflectors · CPC title

• G03F1/76

  Patterning of masks by imaging · CPC title

• G03F7/70058

  Mask illumination systems · CPC title

• G03F7/70283

  Mask effects on the imaging process · CPC title