Extreme Ultraviolet Mask With Backside Coating

• US 20200133114A1
• 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: Jindal, Vibhu, Chandrachood, Madhavi R., Banthia, Vikash
• Granted Patent: US 11,249,386 B2
• Time in Patent Office: Days
• CPC Class Codes: G03F 1/24 Reflection masks; Preparation thereof
• CPC Class Codes: G03F 1/38 Masks having auxiliary features, e.g. special coatings or marks for alignment or testing; Preparation thereof
• CPC Class Codes: G03F 7/70033 by plasma extreme ultraviolet [EUV] sources

Abstract

Extreme ultraviolet (EUV) mask blanks, methods for their manufacture and production systems therefor are disclosed. The EUV mask blanks comprise a substrate having a first side and a second side; a backside coating layer comprising an alloy of tantalum and nickel on the first side of the substrate; a multilayer stack of reflective layers on the second side of 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 on the capping layer.

Claims

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

a substrate having a first side and a second side;

a backside coating layer comprising an alloy of tantalum and nickel on the first side of the substrate;

a multilayer stack of reflective layers on the second side of 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 reflective layers; and

an absorber layer on the capping layer.

2. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the alloy of tantalum and nickel comprises from about 70 to about 85 wt. % tantalum and from about 15 to about 30 wt. % nickel.

3. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the alloy of tantalum and nickel comprises from about 45 to about 55 wt. % tantalum and from about 45 to about 55 wt. % nickel.

4. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the alloy of tantalum and nickel comprises from about 30 to about 45 wt. % tantalum and from about 55 to about 70 wt. % nickel.

5. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the backside coating layer further comprises 0.1 wt. % to about 10 wt. % of a dopant selected from one or more of boron, nitrogen or oxygen.

6. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the backside coating layer comprises a thickness in a range of from 0.1 nm to 50 nm.

7. The extreme ultraviolet (EUV) mask blank of claim 1, wherein the backside coating layer comprises a thickness in a range of from 0.1 nm to 25 nm.

13. The method of claim 6, wherein the alloy of tantalum and nickel is co-sputtered by a gas selected from one or more of argon (Ar), oxygen (O₂), or nitrogen (N₂) to form the backside coating layer.

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

providing a substrate having a first side and a second side;

forming a backside coating layer comprising an alloy of tantalum and nickel on the first side of the substrate;

forming a multilayer stack of reflective layers on the second side of 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.

9. The method of claim 8, wherein the alloy of tantalum and nickel comprises from about 70 to about 85 wt. % tantalum and from about 15 to about 30 wt. % nickel.

10. The method of claim 8, wherein the alloy of tantalum and nickel comprises from about 45 to about 55 wt. % tantalum and from about 45 to about 55 wt. % nickel.

11. The method of claim 8, wherein the alloy of tantalum and nickel comprises from about 30 to about 45 wt. % tantalum and from about 55 to about 70 wt. % nickel.

12. The method of claim 8, wherein the backside coating layer further comprises 0.1 wt. % to about 10 wt. % of a dopant selected from one or more of boron, nitrogen or oxygen.

14. The method of claim 8, wherein the alloy of tantalum and nickel is deposited using a bulk target having a same composition as the alloy of tantalum and nickel and is sputtered using a gas selected from one or more of argon (Ar), oxygen (O₂), or nitrogen (N₂) to form the backside coating layer.

15. The method of claim 8, wherein the backside coating layer comprises a thickness in a range of from 0.1 nm to 50 nm.

16. The method of claim 8, wherein the backside coating layer comprises a thickness in a range of from 0.1 nm to 25 nm.

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

an extreme ultraviolet light source; and

a reticle comprising a substrate having a first side and a second side;

a backside coating layer comprising an alloy of tantalum and nickel on the first side of the substrate;

a multilayer stack on the second side of 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 backside coating layer includes an alloy of tantalum and nickel.

18. The extreme ultraviolet (EUV) lithography system of claim 17, further comprising a capping layer between the multilayer stack and the absorber layer, for protecting the multilayer stack.

19. The extreme ultraviolet (EUV) lithography system of claim 17 wherein the reticle has a pattern that represents a processing layer of an integrated circuit.

20. The extreme ultraviolet (EUV) lithography system of claim 17, further comprising an anti-reflective coating on the absorber layer.