Extreme ultraviolet light (EUV) photomasks, and fabrication methods thereof

Patent metadata

Field	Value
Publication number	US-9869928-B2
Application number	US-201615096009-A
Country	US
Kind code	B2
Filing date	Apr 11, 2016
Priority date	Mar 15, 2013
Publication date	Jan 16, 2018
Grant date	Jan 16, 2018

Abstract

Embodiments of EUV photomasks and methods for forming a EUV photomask are provided. The method comprises providing a substrate, a reflective layer, a capping layer, a hard mask layer, and forming an opening therein. An absorber layer is then filled in the opening and over the top surface of the hard mask layer. A planarized process is provided to remove the absorber layer above the top surface of the hard mask layer and form an absorber in the opening, wherein the absorber has a top portion wider than a bottom portion.

First claim

What is claimed is:

1. A method, the method comprising:
forming a reflective layer over a substrate, the reflective layer comprising a plurality of layers of different materials;
forming a cap layer over the reflective layer;
forming a first opening in the cap layer;
forming a second opening in the reflective layer, the second opening being within the first opening, a width of the second opening being less than a width of the first opening; and
forming an absorber layer in the first opening and the second opening.

2. The method of claim 1 , wherein forming the first opening is performed before forming the second opening.

3. The method of claim 1 , wherein an uppermost surface of the absorber layer is above an uppermost surface of the cap layer.

4. The method of claim 1 , further comprising forming a mask layer over the cap layer prior to forming the first opening.

5. The method of claim 4 , further comprising removing the mask layer after forming the absorber layer.

6. The method of claim 5 , wherein forming the absorber layer comprises, prior to removing the mask layer:
forming an absorber material in the first opening and the second opening, the absorber material extending over an upper surface of the mask layer; and
planarizing the absorber material.

7. The method of claim 6 , after planarizing the absorber material, etching the absorber material.

8. The method of claim 6 , wherein an uppermost surface of the absorber material is recessed below an uppermost surface of the mask layer.

9. The method of claim 6 , wherein an uppermost surface of the absorber material is level with an uppermost surface of the mask layer.

10. A method, the method comprising:
forming a first opening in a cap layer, the cap layer being over a reflective layer, the reflective layer being over a substrate;
forming a second opening in the reflective layer, the second opening being within lateral boundaries of the first opening; and
forming an absorber layer in the first opening and the second opening, the absorber layer extending over at least a portion of the reflective layer.

11. The method of claim 10 , wherein a mask layer is over the cap layer, and forming the first opening comprises forming the first opening in the mask layer.

12. The method of claim 11 , wherein after forming the absorber layer, removing the mask layer.

13. The method of claim 12 , wherein forming the absorber layer comprises:
forming an absorber material over an uppermost surface of the cap layer; and
removing at least a portion of the absorber material, thereby forming the absorber layer.

14. The method of claim 13 , wherein removing at least a portion of the absorber material comprises:
performing a chemical mechanical polishing step to remove at least some of the absorber material; and
after performing the chemical mechanical polishing step, performing a dry etch process to remove at least some of the absorber material.

15. The method of claim 10 , wherein a ratio of a width of the first opening to a width of the second opening is in a range from about 1 to about 2.

16. The method of claim 10 , wherein the absorber layer is TaSi, TaBN, TaN, TaSiON, TaBO, or TaON.

17. The method of claim 10 , wherein the reflective layer comprises a Mo containing layer and a Si containing layer.

18. A photomask, comprising:
a reflective layer over a substrate, the reflective layer comprising alternating layers of a first material and a second material;
a capping layer over the reflective layer; and
an absorber extending through the capping layer and into the reflective layer, wherein a portion of the absorber extends over an uppermost surface of the reflective layer.

19. The photomask of claim 18 , wherein the reflective layer comprises alternating layers of the first material, the second material, and one or more additional materials.

20. The photomask of claim 18 , wherein the absorber comprises a tantalum-based material.

Assignees

• Taiwan Semiconductor Mfg Co Ltd

Inventors

• Huang Tao-Min
• Shih Chih-Tsung
• Chen Chia-Jen
• Lee Hsin-Chang
• Yen Anthony

Classifications

• G03F1/80

  Etching · CPC title

• G03F1/22

  Masks or mask blanks for imaging by radiation of 100nm or shorter wavelength, e.g. X-ray masks, extreme ultraviolet [EUV] masks; Preparation thereof · CPC title

• G03F1/24 Primary

  Reflection masks; Preparation thereof · CPC title

• G03F1/72

  Repair or correction of mask defects · CPC title