Ta-Cu Alloy Material For Extreme Ultraviolet Mask Absorber

• US 20200133111A1
• Filed: 10/24/2019
• Published: 04/30/2020
• Est. Priority Date: 10/26/2018
• Status: Active Grant

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Liu, Shuwei, Jindal, Vibhu, Rastegar, Abbas
• Granted Patent: US 11,209,727 B2
• Time in Patent Office: Days
• CPC Class Codes: G03F 1/22 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 Class Codes: G03F 1/54 Absorbers, e.g. of opaque materials
• CPC Class Codes: G03F 7/7015 Details of optical elements

Abstract

Extreme ultraviolet (EUV) mask blanks, methods for their manufacture and production systems therefor are disclosed. The EUV mask blanks comprise a substrate; a multilayer stack of reflective layers on the substrate; a capping layer on the multilayer stack of reflecting layers; and an absorber layer including an alloy of tantalum and copper on the capping layer.

Claims

1. An extreme ultraviolet (EUV) mask blank comprising:

a substrate;

a multilayer stack of reflective layers on the substrate, the multilayer stack of reflective layers including a plurality of reflective layers including reflective layer pairs;

a capping layer on the multilayer stack of reflecting layers; and

an absorber layer comprising an alloy of tantalum and copper.

2. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the alloy of tantalum and copper is a tantalum rich alloy comprising from about 50 to about 85 wt. % tantalum and from about 15 to about 50 wt. % copper.

3. The extreme ultraviolet (EUV) mask blank of claim 2, wherein the tantalum rich alloy comprises from about 60.5 to about 72.7 wt. % tantalum and from about 27.3 to about 39.5 wt. % copper.

4. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the alloy of tantalum and copper is a copper rich alloy comprising from about 65 to about 95 wt. % copper and from about 5 to about 35 wt. % tantalum.

5. The extreme ultraviolet (EUV) mask blank of claim 4, wherein the copper rich alloy comprises from about 80.7 to about 83.3 wt. % copper and from about 27.3 to about 39.5 wt. % tantalum.

6. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the absorber layer has a thickness of less than 45 nm.

7. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the absorber layer has a reflectivity of less than about 2% and is etch selective relative to the capping layer.

8. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the absorber layer further comprises 0.1 wt. % to about 5 wt. % of a dopant selected from one or more of nitrogen or oxygen.

9. The extreme ultraviolet (EUV) mask blank of claim 1, further comprising a second absorber layer that includes TiN.

10. A method of manufacturing an extreme ultraviolet (EUV) mask blank comprising:

forming on a substrate a multilayer stack of reflective layers on the substrate, the multilayer stack of reflective layers including a plurality of reflective layer pairs;

forming a capping layer on the multilayer stack of reflective layers; and

forming an absorber layer on the capping layer, the absorber layer comprising an alloy of tantalum and copper.

11. The method of claim 10, wherein the alloy of tantalum and copper is a tantalum rich alloy comprising from about 50 to about 85 wt. % tantalum and from about 15 to about 50 wt. % copper.

12. The method of claim 11, wherein the tantalum rich alloy comprises from about 60.5 to about 72.7 wt. % tantalum and from about 27.3 to about 39.5 wt. % copper.

13. The method of claim 10, wherein the alloy of tantalum and copper is a copper rich alloy comprising from about 65 to about 95 wt. % copper and from about 5 to about 35 wt. % tantalum.

14. The method of claim 13, wherein the copper rich alloy comprises from about 80.7 to about 83.3 wt. % copper and from about 27.3 to about 39.5 wt. % tantalum.

15. The method of claim 10, wherein the alloy of tantalum and copper is co-sputtered by a gas selected from one or more of argon (Ar), oxygen (O₂), or nitrogen (N₂) to form the absorber layer.

16. The method of claim 10, wherein the alloy of tantalum and copper is deposited using a bulk target having a same composition as the alloy of tantalum and copper and is sputtered using a gas selected from one or more of argon (Ar), oxygen (O₂), or nitrogen (N₂) to form the absorber layer.

17. An extreme ultraviolet (EUV) EUV lithography system comprising:

an extreme ultraviolet light source; and

a reticle comprising a substrate;

a multilayer stack over the substrate; and

an absorber layer, over the multilayer stack, with a thickness of less than 80 nm and less than 2% reflectivity of an extreme ultraviolet (EUV) light at a wavelength of 13.5 nm, wherein the absorber layer includes an alloy of tantalum and copper.

18. The system as claimed in claim 17 further comprising a capping layer between the multilayer stack and the absorber layer, for protecting the multilayer stack.

19. The system as claimed in claim 17 wherein the reticle has a pattern that represents a processing layer of an integrated circuit.

20. The system as claimed in claim 17, further comprising an anti-reflective coating on the absorber layer.