Target and process for its production, and method for forming a film having a high refractive index

• US 6,440,278 B1
• Filed: 09/28/2001
• Issued: 08/27/2002
• Est. Priority Date: 08/23/1995
• Status: Expired due to Term

• Current Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Original Assignee: Asahi Glass Company, Limited (AGC, Inc.)
• Inventors: Hayashi, Atsushi, Mitsui, Akira, Osaki, Hisashi, Kida, Otojiro, Suzuki, Eri
• Primary Examiner(s): VerSteeg, Steven H.
• Application Number:
  US09/964,625
• Publication Number:
  US 20020027817A1
• Time in Patent Office: 333 Days
• Field of Search: 204/192.15, 204/192.22, 204/298.13, 420/425, 148/422, 427/453, 427/454
• US Class Current: 204/192.22
• CPC Class Codes: C23C 14/083 of refractory metals or yttrium
• CPC Class Codes: C23C 14/3414 Metallurgical or chemical aspects of target preparation, e.g. casting, powder metallurgy
• CPC Class Codes: C23C 4/02 Pretreatment of the material to be coated, e.g. for coating on selected surface areas
• CPC Class Codes: C23C 4/11 Oxides

Abstract

A sputtering target comprising a substrate and a target material formed on the substrate, wherein the target material comprises a metal oxide of the chemical formula MO_x as the main component, wherein MO_x is a metal oxide which is deficient in oxygen as compared with the stoichiometric composition, and M is at least one metal selected from the group consisting of Ti, Nb, Ta, Mo, W, Zr and Hf, a process for its production, and a method for forming a film having a high refractive index.

Claims

1. A sputtering target comprising a substrate and a target material formed on the substrate, wherein

the target material comprises as a main component an oxygen deficient oxide;

and

the oxygen deficient oxide comprises a metal oxide of a chemical formula NbO_x where 2<

x<

2.5, wherein

the target material has a resistivity of at most 10 Ω

cm at room temperature.

2. The sputtering target according to claim 1, wherein the target material has a resistivity of at most 1 Ω

cm at room temperature.

3. The sputtering target according to claim 1, produced by a plasma spraying process.

4. The sputtering target according to claim 1, wherein the substrate is a surface-roughened substrate.

5. The sputtering target according to claim 1, wherein the substrate is a cylindrical substrate.

6. A method of making a sputtering target, the method comprising

forming a target material by plasma spraying a ceramic powder in a semi-molten state in a high temperature plasma gas in a reducing atmosphere onto a substrate, wherein

the target material comprises as a main component an oxygen deficient oxide;

and

the oxygen deficient oxide comprises a metal oxide of a chemical formula NbO_x where 2<

x<

2.5.

7. The method according to claim 6, further comprising forming an undercoat made of metal or alloy between the substrate and the target material.

8. The method according to claim 7, wherein the undercoat is at least one of

a layer having a thermal expansion coefficient intermediate between a thermal expansion coefficient of the target material and a thermal expansion coefficient of the substrate and

a layer having a thermal expansion coefficient close to the thermal expansion coefficient of the target material.

9. The method according to claim 7, wherein the plasma spraying is water plasma spraying.

10. A method for forming a film, the method comprising sputtering a target, wherein

the sputtering target comprises a substrate and a target material formed on the substrate;

the target material comprises as a main component an oxygen deficient oxide; and

the oxygen deficient oxide comprises a metal oxide of a chemical formula NbO_x where 2<

x<

2.5.

11. The method according to claim 10, wherein the sputtering is DC sputtering.

12. The method according to claim 10, wherein the target has a resistivity of at most 10 Ω

cm.

13. The method according to claim 10, wherein the sputtering is carried out in an argon atmosphere or in a mixed atmosphere of argon and oxygen.

14. The method according to claim 13, wherein the mixed atmosphere of argon and oxygen comprises at least 10 vol % oxygen.

15. The method according to claim 10, further comprising forming a film having a refractive index of 2.3.

16. A sputtering target comprising

a substrate;

a target material formed on the substrate; and

an undercoat of a metal or alloy between the target material and the substrate, wherein

the target material comprises as a main component an oxygen deficient oxide; and

the oxygen deficient oxide comprises a metal oxide of a chemical formula NbO_x where 2<

x<

2.5.

17. The sputtering target according to claim 16, wherein the substrate is a cylindrical substrate.

18. The sputtering target according to claim 16, wherein the substrate is a surface-roughened substrate.

19. The sputtering target according to claim 16, wherein the undercoat has a thermal expansion coefficient between a thermal expansion coefficient of the target material and a thermal expansion coefficient of the substrate.

20. The sputtering target according to claim 19, wherein the thermal expansion coefficient of the undercoat is from 12×

10<sup>−

6</sup> to 15×

10<sup>−

6</sup>/°

C.

21. The sputtering target according to claim 16, wherein the undercoat comprises

a first layer, which is adjacent to the substrate and which has a thermal expansion coefficient between the thermal expansion coefficient of the target material and the thermal expansion coefficient of the substrate; and

a second layer, which is adjacent to the target material and which has a thermal expansion coefficient within a range of ±

2×

10<sup>−

6</sup>/°

C. of a thermal expansion coefficient of the target material.

22. The sputtering target according to claim 16, wherein the undercoat comprises a material selected from the group consisting of Mo, Ti, Ni, Nb, Ta, W, Ni—

Al, Ni—

Cr, Ni—

Cr—

Al, Ni—

Cr—

Al—

Y and Ni—

Co—

Cr—

Al—

Y.

23. The sputtering target according to 16, wherein the undercoat has a thickness of from 30 to 100 μ

m.

24. The sputtering target according to claim 16, wherein the undercoat has a thermal expansion coefficient within a range of ±

2×

10<sup>−

6</sup>/°

C. of a thermal expansion coefficient of the target material.

25. The sputtering target according to claim 24, wherein the thermal expansion coefficient of the undercoat is from 4×

10<sup>−

6</sup> to 11×

10<sup>−

6</sup>/°

C.

26. The sputtering target according to claim 16, wherein the target material has a thickness of from 2 to 10 mm.

27. The sputtering target according to claim 16, wherein the target has a resistivity of at most 10 Ω

cm.

28. A method of making a sputtering target, the method comprising

providing an undercoat on a substrate;

depositing a target material on the undercoat; and

forming the sputtering target of claim 16.

29. The method of claim 28, wherein the depositing comprises plasma spraying.

30. A method of using a sputtering target, the method comprising sputtering the sputtering target of claim 16.