Method of depositing a thin metallic film and related apparatus

• US 20030016116A1
• Filed: 07/23/2001
• Published: 01/23/2003
• Est. Priority Date: 07/23/2001
• Status: Abandoned Application

• Current Assignee: Akima Corp. (NANA Regional Corporation Incorporated)
• Original Assignee: Akima Corp. (NANA Regional Corporation Incorporated)
• Inventors: Blaha, Charles A.
• Application Number:
  US09/910,973
• Publication Number:
  US 20030016116A1
• Time in Patent Office: Days
• US Class Current: 338/2
• CPC Class Codes: G01K 7/02 using thermoelectric elements, e.g. thermocouples
• CPC Class Codes: G01L 1/2287 constructional details of the strain gauges adjustable resistors H01C10/00
• CPC Class Codes: G03F 7/00 Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor using photoresist structures for special production processes, see the relevant places, e.g. B44C, H01L, e.g. H01L21/00, H05K
• CPC Class Codes: H01C 17/003 using lithography, e.g. photolithography lithographic compositions and processing in general G03F
• CPC Class Codes: H01C 17/288 by thin film techniques
• CPC Class Codes: H05K 3/064 Photoresists
• CPC Class Codes: H05K 3/143 Masks therefor H05K3/048 takes precedence

Abstract

A method of depositing a thin metal film using photolithography is disclosed. The method includes the deposition of a sacrificial metal layer on a substrate. Photolithography processing forms a pattern on the sacrificial metal layer that is removed prior to sputter deposition of the thin metal film.

Claims

1. A method of depositing a thin metallic film comprising:

a. depositing a layer of etchable metal onto a substrate;

b. applying a photoresist to the etchable metal layer;

c. developing the photoresist to expose selected portions of the etchable metal layer;

d. etching the exposed portions of the etchable metal layer to expose selected portions of the substrate;

e. depositing a metallic material on the exposed substrate while substantially preventing carbonization of the photoresist during deposition of the metallic material;

f. removing the remaining photoresist; and

g. removing the remaining etchable metal layer.

2. A method according to claim 1 wherein the etchable metal is selected from the group consisting of copper, aluminum and nickel.

3. A method according to claim 1 wherein the etchable metal is copper.

4. A method according to claim 1 wherein the photoresist is a positive photoresist.

5. A method according to claim 1 wherein the etching step comprises chemical etching.

6. A method according to claim 5 wherein the etching step comprises chemical etching with a nitric acid solution.

7. A method according to claim 1 wherein the deposition of the metallic material is accomplished by sputtering.

8. A method according to claim 1 wherein the step of eliminating or substantially preventing carbonization of the photoresist comprises using low power sputtering.

9. A method according to claim 8 wherein the sputtering occurs at a power level of no more than 0.16 W/cm².

10. A method according to claim 1 wherein the metallic material is selected from the group comprising platinum, palladium, rhodium, gold, silver, titanium, tungsten, chromium, and alloys thereof.

11. A method according to claim 1 wherein the step of substantially preventing carbonization of the photoresist comprises cooling of the substrate during the metallic deposition step.

12. A method according to claim 11 wherein the step of substantially preventing carbonization of the photoresist comprises placing the substrate in contact with a cooled substrate holder during deposition of the metallic material.

13. A method according to claim 1 wherein the substrate is selected from the group comprising ceramics, metals, silicon, silicon carbide, polymer films, and Group III nitrides.

14. A method according to claim 1 further comprising depositing a layer of insulating material on the substrate prior to depositing the layer of etchable metal.

15. A method according to claim 1 wherein the substrate is an insulating material.

16. A method according to claim 14 wherein the insulating layer is selected from the group consisting of insulating oxides, insulating glass, insulating ceramics and insulating polymers.

17. A method according to claim 15 wherein the insulating material is selected from the group consisting of insulating oxides, insulating glass, insulating ceramics and insulating polymers.

19. A method according to claim 18 wherein the metallic material is deposited by sputtering.

20. A method according to claim 19 wherein the sputtering occurs at a power level of no more than 0.16 W/cm2.

21. A method according to claim 18 wherein said metallic material is selected from the group comprising platinum, palladium, rhodium, gold, silver, titanium, tungsten, chromium, and alloys thereof.

22. A method according to claim 18 further comprising cooling the substrate during deposition of the metallic material.

23. A method according to claim 18 wherein the substrate is selected from the group comprising ceramics, metals, silicon, silicon carbide, polymer films, and Group III nitrides.

24. A method according to claim 18 further comprising depositing a layer of insulating material on the substrate prior to depositing the layer of copper.

25. A method according to claim 18 wherein the substrate is an insulating material.

26. A method according to claim 24 wherein the insulating layer is selected from the group consisting of insulating oxides, insulating glass, insulating ceramics and insulating polymers.

27. A method according to claim 25 wherein the insulating material is selected from the group consisting of insulating oxides, insulating glass, insulating ceramics and insulating polymers.

29. A strain gauge according to claim 28 wherein the deposited metal is platinum.

30. A strain gauge according to claim 28 wherein the deposited metal is gold.

31. A strain gauge according to claim 28 further comprising an insulating layer in contact with said deposited metal.

32. A strain gauge according to claim 31 wherein said insulating layer is selected from the group consisting of insulating oxides, insulating glass, insulating ceramics and insulating polymers.

33. A strain gauge according to claim 32 wherein said insulating material is aluminum oxide.

34. A strain gauge according to claim 28 wherein the strain gauge is in contact with a curved substrate.

35. A strain gauge according to claim 28 wherein said grid lines are less than 100 microns wide.

36. A strain gauge according to claim 28 wherein said grid lines are less than 50 microns wide.

37. A strain gauge according to claim 28 wherein said grid lines are less than 10 microns wide.

39. A thin film thermocouple according to claim 38 further comprising a layer of insulating material between said substrate and said first and second thin films.

40. A thermocouple according to claim 39 wherein the insulating layer is selected from the group consisting of insulating oxides, insulating glass, insulating ceramics and insulating polymers.

41. A thermocouple according to claim 40 wherein said insulating layer is aluminum oxide.

42. A thermocouple according to claim 38 wherein the metal used for one of the thin films is platinum.

43. A thermocouple according to claim 38 wherein the metal used for one of the thin films is gold.

44. A thermocouple according to claim 38 wherein the substrate is curved.

45. A thermocouple according to claim 38 wherein said thermocouple comprises thin film structures less than 100 microns wide.

46. A thermocouple according to claim 38 wherein said thermocouple comprises thin film structures less than 50 microns wide.

47. A thermocouple according to claim 38 wherein said thermocouple comprises thin film structures less than 10 microns wide.

48. A thermocouple according to claim 38 wherein said substrate is an insulating material.

49. A thermocouple according to claim 48 wherein said insulating material is selected from the group consisting of insulating oxides, insulating glass, insulating ceramics and insulating polymers.

50. A transducer manufactured according to the method of claim 1.

18. A method of depositing a thin metallic film comprising:

a. depositing a layer of copper onto a substrate;

b. applying a positive photoresist to the copper layer;

c. softbaking the photoresist;

d. exposing the photoresist through a photomask;

e. developing the photoresist to expose a portion of the copper layer;

f. chemically etching the exposed copper layer with nitric acid to expose a portion of the substrate;

g. depositing a metallic material on the exposed substrate while substantially preventing photoresist carbonization during deposition of the metallic material;

h. removing the remaining photoresist; and

i. removing the remaining copper.

51. A transducer manufactured according to the method of claim 18.

28. A strain gauge comprising a meandering arrangement of grid lines, said grid lines comprising a thin film of a photolithographically deposited metal.

38. A thin film thermocouple comprising:

a substrate;

a first thin film of photolithographically deposited metal on said substrate; and

a second thin film of a photolithographically deposited metal on said substrate;

said first and second films arranged to form a thermocouple.