Graded interface in Bragg reflector

Patent metadata

Field	Value
Publication number	US-11720013-B2
Application number	US-202217708593-A
Country	US
Kind code	B2
Filing date	Mar 30, 2022
Priority date	Apr 19, 2019
Publication date	Aug 8, 2023
Grant date	Aug 8, 2023

Abstract

A multilayer stack in the form of a Bragg reflector comprising a graded interfacial layer and a method of manufacturing are disclosed. The graded interfacial layer eliminates the formation of low-reflectivity interfaces in a multilayer stack and reduces roughness of interfaces in a multilayer stack.

First claim

What is claimed is:

1. A method of manufacturing a Bragg reflector comprising alternating layers of first reflective material layer A and second reflective material layer B, the method comprising:
depositing a uniform first reflective material layer A on a substrate;
forming a first graded interfacial layer on the uniform first reflective material layer A, wherein the first graded interfacial layer comprises a thickness and a density gradient that changes across the thickness;
depositing a uniform second reflective material layer B on the first graded interfacial layer; and
forming a second graded interfacial layer on the uniform second reflective material layer B, wherein the second graded interfacial layer comprises a thickness and a density gradient that changes across the thickness, wherein the Bragg reflector is formed in a physical vapor deposition (PVD) chamber comprising a first material target A and a second material target B, wherein the PVD chamber comprises a rotating shield with a pair of shield holes comprising a first shield hole and a second shield hole.

2. The method of claim 1 , wherein the first graded interfacial layer and the second graded interfacial layer each comprises the first material A and the second material B and a composition gradient that changes across the thickness.

3. The method of claim 2 , wherein the first reflective material layer A comprises one of molybdenum (Mo) or silicon (Si), and the second reflective material layer B comprises the other of molybdenum (Mo) or silicon (Si).

4. The method of claim 2 , wherein the first graded interfacial layer and the second graded interfacial layer independently comprise MoSi x .

5. The method of claim 2 , wherein depositing the uniform first reflective material layer A and depositing the uniform second reflective material layer B comprises using a constant deposition power and a constant gas pressure.

6. The method of claim 2 , wherein forming the first graded interfacial layer and forming the second graded interfacial layer comprises reducing deposition power gradually and simultaneously increasing gas pressure.

7. A method of manufacturing a Bragg reflector, the method comprising:
depositing a uniform first reflective material layer A on a substrate;
forming a first graded interfacial layer on the first reflective material layer A, wherein the first graded interfacial layer comprises a gradient composition;
depositing a uniform second reflective material layer B on the first graded interfacial layer; and
forming a second graded interfacial layer on the second reflective material layer B, wherein the second graded interfacial layer comprises a gradient composition, wherein the first graded interfacial layer and the second graded interfacial layer each comprises the first material A and the second material B.

8. The method of claim 7 , wherein the Bragg reflector is formed in a physical vapor deposition (PVD) chamber comprising a first material target A and a second material target B, wherein the PVD chamber comprises a rotating shield with a pair of shield hole comprising a first shield hole and a second shield hole.

9. The method of claim 8 , wherein the uniform first reflective material layer A is deposited by exposing the first material target A through the first shield hole and sputtering the first material target A, the uniform second reflective material layer B is formed by exposing the second material target B through the second shield hole, and the first graded interfacial layer and the second graded interfacial layer are formed by exposing the first material target A through the first shield hole and the second material target B through the second shield hole and co-sputtering the first material target A and the second material target B.

10. The method of claim 9 , wherein the uniform first reflective material layer A comprises one of molybdenum (Mo) or silicon (Si), the uniform second reflective material layer B comprises the other of molybdenum (Mo) or silicon (Si), and the first graded interfacial layer and the second graded interfacial layer each comprises MoSi x .

11. The method of claim 9 , wherein depositing the uniform first reflective material layer A comprises applying a constant deposition power to a first material target A and a constant gas pressure and depositing the uniform second reflective material layer B comprises using a constant deposition power applied on a second material target B and a constant gas pressure.

12. The method of claim 9 , wherein forming the first graded interfacial layer comprises reducing deposition power applied to the first material target A and simultaneously gradually increasing deposition power applied to the second material target B.

13. The method of claim 12 , wherein forming the second graded interfacial layer comprises gradually reducing deposition power applied to the second material target B and simultaneously gradually increasing the deposition power applied to the first material target A.

14. The method of claim 8 , wherein the graded interfacial layers have a first region rich in material A adjacent to the first layer and a second region rich in material B adjacent to the second layer.

15. The method of claim 10 , wherein where x is a number from 0 to 2, and the material A comprises Si and the material B comprises Mo.

16. The EUV mask blank of claim 15 , wherein the graded interfacial layers have a first region rich in Mo adjacent to the first layer and a second region rich in Si adjacent to the second layer.

Assignees

• Applied Materials Inc

Inventors

• Xiao Wen
• Jindal Vibhu
• Li Weimin
• Liu Shuwei

Classifications

• G03F7/70316

  Details of optical elements, e.g. of Bragg reflectors, extreme ultraviolet [EUV] multilayer or bilayer mirrors or diffractive optical elements · CPC title

• G03F7/7015

  Details of optical elements · CPC title

• G03F1/52

  Reflectors · CPC title

• G03F1/24 Primary

  Reflection masks; Preparation thereof · CPC title

• G02B5/0891

  Ultraviolet [UV] mirrors (apparatus for microlithography exposure G03F7/70; X-ray multilayer structures G21K1/06) · CPC title