Method for Extreme Ultraviolet Lithography Mask Treatment

• US 20190324364A1
• Filed: 04/18/2018
• Published: 10/24/2019
• Est. Priority Date: 04/18/2018
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Hsu, Pei-Cheng, Su, Yih-Chen, Tsai, Chi-Kuang, Lien, Ta-Cheng, Wang, Tzu Yi, Chang, Jong-Yuh, Lee, Hsin-Chang
• Granted Patent: US 11,048,158 B2
• Time in Patent Office: Days
• CPC Class Codes: G03F 1/24 Reflection masks; Preparation thereof
• CPC Class Codes: G03F 1/26 Phase shift masks [PSM]; PSM blanks; Preparation thereof
• CPC Class Codes: G03F 1/54 Absorbers, e.g. of opaque materials
• CPC Class Codes: G03F 1/80 Etching
• CPC Class Codes: G03F 1/82 Auxiliary processes, e.g. cleaning or inspecting
• CPC Class Codes: G03F 1/84 Inspecting
• CPC Class Codes: G03F 7/70433 Layout for increasing efficiency or for compensating imaging errors, e.g. layout of exposure fields for reducing focus errors; Use of mask features for increasing efficiency or for compensating imaging errors
• CPC Class Codes: G03F 7/70466 Multiple exposures, e.g. combination of fine and coarse exposures, double patterning or multiple exposures for printing a single feature stitching G03F7/70475
• CPC Class Codes: H01L 21/2633 for etching, e.g. sputteretching

Abstract

A method comprises receiving a workpiece that includes a substrate having a low temperature expansion material, a reflective multilayer over the substrate, a capping layer over the reflective multilayer, and an absorber layer over the capping layer. The method further comprises patterning the absorber layer to provide first trenches corresponding to circuit patterns on a wafer, and patterning the absorber layer, the capping layer, and the reflective multilayer to provide second trenches corresponding to a die boundary area on the wafer, thereby providing an extreme ultraviolet lithography (EUVL) mask. The method further comprises treating the EUVL mask with a treatment chemical that prevents exposed surfaces of the absorber layer from oxidation.

Claims

1. A method, comprising:

receiving a workpiece that includes a substrate having a low temperature expansion material, a reflective multilayer over the substrate, a capping layer over the reflective multilayer, and an absorber layer over the capping layer;

first patterning the absorber layer to provide first trenches corresponding to circuit patterns on a wafer;

second patterning the absorber layer, the capping layer, and the reflective multilayer to provide second trenches corresponding to a die boundary area on the wafer, thereby providing an extreme ultraviolet lithography (EUVL) mask; and

treating the EUVL mask with one or more chemical elements that prevent exposed surfaces of the absorber layer from oxidation.

2. The method of claim 1, wherein the treating of the EUVL mask includes applying nitrogen plasma to the EUVL mask.

3. The method of claim 2, wherein the nitrogen plasma is applied with a bias power substantially equal to 0.

4. The method of claim 2, wherein the absorber layer comprises tantalum (Ta), and the applying of the nitrogen plasma to the EUVL mask results in a ratio of N to Ta (N:

Ta) in a surface layer of the absorber layer to be greater than or equal to 1.25.

5. The method of claim 1, wherein the one or more chemical elements include fluorine.

6. The method of claim 1, further comprising:

exposing one or more wafers with the EUVL mask; and

cleaning the EUVL mask with deionized water (DIW).

7. The method of claim 6, further comprising:

inspecting surfaces of the EUVL mask; and

on condition that the surfaces of the EUVL mask are found to have particles bigger than a size threshold, treating the EUVL mask with the one or more chemical elements, and cleaning the EUVL mask with another cleaning chemical that provides stronger oxidizing power than DIW.

8. The method of claim 7, wherein the another cleaning chemical comprises hydrogen peroxide, sulfuric acid, hydrogen fluoride acid, or a sulfuric peroxide mixture.

9. The method of claim 1, wherein each of the first patterning and the second patterning includes:

coating a photoresist layer over the workpiece;

exposing the photoresist layer using electron beam;

developing the photoresist layer to form photoresist patterns; and

etching the workpiece with the photoresist patterns as an etch mask.

10. A method, comprising:

receiving a workpiece that includes a substrate having a low temperature expansion material, a reflective multilayer over the substrate, a capping layer having ruthenium over the reflective multilayer, and an absorber layer having tantalum over the capping layer;

patterning the absorber layer, the capping layer, and the reflective multilayer to provide first trenches corresponding to circuit patterns on a wafer and second trenches corresponding to a die boundary area on the wafer, thereby providing an extreme ultraviolet lithography (EUVL) mask; and

treating the EUVL mask with nitrogen plasma.

11. The method of claim 10, wherein the nitrogen plasma is applied with a bias power substantially equal to 0 such that the capping layer is substantially not altered by the nitrogen plasma.

12. The method of claim 10, wherein the nitrogen plasma is applied with duration ranging from 30 seconds to 120 seconds, source power ranging from 350 Watts to 1000 Watts, and pressure ranging from 1 mtorr to 10 mtorr.

13. The method of claim 10, wherein the nitrogen plasma is applied in a manner to produce a surface layer of the absorber layer to have a ratio of N to Ta (N:

Ta) greater than or equal to 1.25.

14. The method of claim 10, further comprising:

exposing one or more wafers with the EUVL mask;

inspecting surfaces of the EUVL mask; and

on condition that the surfaces of the EUVL mask are found to have particles larger than a size threshold, treating the EUVL mask with second nitrogen plasma.

15. The method of claim 14, after the treating of the EUVL mask with the second nitrogen plasma, further comprising:

cleaning the EUVL mask with a cleaning chemical that provides stronger oxidizing power than deionized water (DIW).

16. The method of claim 15, wherein the cleaning chemical comprises hydrogen peroxide, sulfuric acid, hydrogen fluoride acid, or a sulfuric peroxide mixture.

17. The method of claim 14, after the inspecting of the surfaces of the EUVL mask and on condition that the surfaces of the EUVL mask are found not to have particles larger than the size threshold, further comprising:

cleaning the EUVL mask with deionized water (DIW).

18. A method, comprising:

exposing one or more wafers with an extreme ultraviolet lithography (EUVL) mask;

inspecting surfaces of the EUVL mask;

on condition that the surfaces of the EUVL mask are found to have particles larger than a size threshold, treating the EUVL mask with nitrogen plasma; and

after the treating of the EUVL mask with the nitrogen plasma, cleaning the EUVL mask with a cleaning chemical including hydrogen peroxide, sulfuric acid, hydrogen fluoride acid, or a sulfuric peroxide mixture.

19. The method of claim 18, after the inspecting of the surfaces of the EUVL mask and on condition that the surfaces of the EUVL mask are found not to have particles larger than the size threshold, further comprising:

cleaning the EUVL mask with deionized water (DIW).

20. The method of claim 18, wherein the EUVL mask includes an absorber layer comprising tantalum (Ta), and the treating of the EUVL mask with the nitrogen plasma is applied in a manner to result in a ratio of N to Ta (N:

Ta) in a surface layer of the absorber layer to be greater than or equal to 1.25.