Methods of forming integrated optoelectronic devices

• US 6,942,814 B2
• Filed: 12/02/2002
• Issued: 09/13/2005
• Est. Priority Date: 11/12/1999
• Status: Expired due to Term

• Current Assignee: Memscap Incorporated
• Original Assignee: Memscap Incorporated
• Inventors: Wood, Robert L., Hill, Edward A.
• Primary Examiner(s): Ahmed, Shamim
• Application Number:
  US10/307,771
• Publication Number:
  US 20030117679A1
• Time in Patent Office: 1,016 Days
• Field of Search: 216/2, 216/17, 216/18, 216/66, 216/24, 359/224
• US Class Current: 216/24
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

Methods of forming optoelectronic devices include forming an electrically conductive layer on a first surface of a substrate and forming a mirror backing layer from the electrically conductive layer by forming an endless groove that extends through the electrically conductive layer. A step is then performed to remove a portion of the substrate at a second surface thereof, which extends opposite the first surface. This step exposes a front surface of the mirror backing layer. An optically reflective mirror surface is then formed on the front surface of the mirror backing layer.

Claims

1. A method of forming an optoelectronic device, comprising the steps of:

forming an electrically conductive layer on a substrate having a first electrically insulating layer thereon;

forming a mirror backing layer from the electrically conductive layer, by forming a groove that extends through the electrically conductive layer and exposes a first surface of the first electrically insulating layer;

removing a portion of the substrate and corresponding portion of the first electrically insulating layer to expose a front surface of the mirror backing layer;

forming an optically reflective mirror surface on the front surface of the mirror backing layer; and

recessing the first electrically insulating layer to expose a portion of the mirror blocking layer that is not covered by the optically reflective mirror surface.

2. The method of claim 1, wherein said step of forming a groove is followed by the step of forming a sacrificial insulating region in the groove.

3. The method of claim 2, wherein said recessing step comprises selectively etching the first electrically insulating layer and the sacrificial insulating region in the groove, using the optically reflective mirror surface as an etching mask.

4. The method of claim 2, wherein said step of forming a sacrificial insulating region in the groove comprises thermally oxidizing at least one sidewall of the mirror backing layer that is exposed by the groove.

5. The method of claim 3, wherein said step of forming a sacrificial insulating region in the groove comprises thermally oxidizing at least one sidewall of the mirror backing layer that is exposed by the groove.

6. The method of claim 3, wherein said step of forming a sacrificial insulating region in the groove comprises the steps of:

thermally oxidizing at least one sidewall of the mirror backing layer that is exposed by the groove; and

then

depositing a silicate glass layer in the groove.

7. The method of claim 2, wherein said step of forming a sacrificial insulating region in the groove is followed by the step of forming a hinge comprising a flexible material on a back surface of the mirror backing layer and on the sacrificial insulating region.

8. The method of claim 7, wherein said recessing step comprises selectively etching the first electrically insulating layer and the sacrificial insulating region in the groove, to expose the hinge.

9. The method of claim 8, wherein said selectively etching step comprises selectively etching the first electrically insulating layer and the sacrificial insulating region using the optically reflective mirror surface as an etching mask.

10. The method of claim 2, wherein said step of forming a sacrificial insulating region in the groove is followed by the step of forming a polysilicon hinge that extends on the sacrificial insulating region and is attached to a back surface of the mirror backing layer.

11. The method of claim 10, wherein the groove defines a polygon-shaped mirror backing layer;

and wherein said step of forming a polysilicon hinge comprises forming a polysilicon hinge that is attached to a portion of the electrically conductive layer extending outside a periphery of the groove.

12. The method of claim 6, wherein said step of forming a sacrificial insulating region in the groove is followed by the step of forming a polysilicon hinge that extends on the silicate glass layer and is attached to the back surface of the mirror backing layer.

13. The method of claim 12, wherein said step of forming a polysilicon hinge comprises forming a polysilicon hinge that is attached to a portion of the electrically conductive layer extending outside a periphery of the groove.

14. The method of claim 13, wherein said recessing step comprises selectively etching the first electrically insulating layer, the thermally oxidized sidewall of the mirror backing layer and the silicate glass layer, to expose the polysilicon hinge.

15. The method of claim 14, wherein said selectively etching step comprises selectively etching the first electrically insulating layer using the optically reflective mirror surface as an etching mask.

16. The method of claim 1, wherein the electrically conductive layer comprises a monocrystalline silicon layer having a thickness greater than about 10 μ

m; and

wherein said step of forming a mirror backing layer comprises the step of selectively deep reactive ion etching the monocrystalline silicon layer to form a mirror backing layer.

17. The method of claim 11, further comprising the step of forming a first electrostatic clamp electrode that extends across the groove and is attached to the back surface of the mirror backing layer.

18. The method of claim 17, wherein said step of forming a mirror backing layer from the electrically conductive layer is preceded by the step of forming a silicon nitride layer on the electrically conductive layer;

and wherein said step of forming a polysilicon hinge is preceded by the step of selectively etching the silicon nitride layer to expose a first portion of the electrically conductive layer and expose first and second portions of the back surface of the mirror backing layer.

19. The method of claim 18, wherein said steps of forming a polysilicon hinge and forming a first electrostatic clamp electrode comprise depositing a polysilicon layer on the exposed first portion of the electrically conductive layer and on the exposed first and second portions of the back surface of the mirror backing layer.

20. The method of claim 19, wherein said step of forming an optically reflective mirror surface comprises evaporating or sputtering a layer of gold on the front surface of the mirror backing layer.

21. The method of claim 1, wherein said step of forming an optically reflective mirror surface comprises evaporating or sputtering a layer of gold on the front surface of the mirror backing layer.

22. The method of claim 16, wherein the substrate comprises a monocrystalline silicon substrate having a thickness greater than 100 μ

m; and

wherein said step of removing a portion of the substrate comprises selectively etching the monocrystalline silicon substrate using a deep reactive ion etching technique.

23. The method of claim 11, wherein the electrically conductive layer comprises a monocrystalline silicon layer having a thickness greater than about 10 μ

m; and

wherein said step of forming a mirror backing layer comprises forming a mirror backing layer from the electrically conductive layer by selectively etching the electrically conductive layer using a deep reactive ion etching technique.

24. The method of claim 23, wherein the substrate comprises a monocrystalline silicon substrate having a thickness greater than 100 μ

m; and

wherein said step of removing a portion of the substrate comprises selectively etching the monocrystalline silicon substrate using a deep reactive ion etching technique.

25. The method of claim 1, wherein said step of removing a portion of the substrate is followed by the step of electroplating a layer of nickel onto a back surface of the mirror backing layer.

26. The method of claim 9, wherein said step of removing a portion of the substrate is followed by the step of electroplating a layer of nickel onto the back surface of the mirror backing layer.

27. The method of claim 19, wherein said step of removing a portion of the substrate is followed by the steps of:

selectively etching the silicon nitride layer to expose a third portion of the back surface of the mirror backing layer; and

electroplating a layer of nickel onto the third portion of the back surface of the mirror backing layer.

28. The method of claim 20, wherein said step of removing a portion of the substrate is followed by the steps of:

selectively etching the silicon nitride layer to expose a third portion of the back surface of the mirror backing layer; and

electroplating a layer of nickel onto the third portion of the back surface of the mirror backing layer.

29. The method of claim 22, wherein said step of removing a portion of the substrate is followed by the step of electroplating a layer of nickel onto a back surface of the mirror backing layer.

30. A method of forming an optoelectronic device, comprising the steps of:

forming an electrically conductive layer on a first surface of a substrate;

forming a mirror backing layer from the electrically conductive layer by forming a groove that extends through the electrically conductive layer;

removing a portion of the substrate at a second surface thereof extending opposite the first surface, to expose a front surface of the mirror backing layer; and

forming an optically reflective mirror surface on the front surface of the mirror backing layer.

31. The method of claim 30, wherein the electrically conductive layer comprises a monocrystalline silicon conductive layer having a thickness of greater than about 10 μ

m; and

wherein said step of forming a mirror backing layer comprises etching a groove in the monocrystalline silicon conductive layer using a deep reactive ion etching technique.

32. The method of claim 30, wherein the substrate comprises a supporting layer of monocrystalline silicon having a thickness of greater than about 100 μ

m; and

wherein said step of removing a portion of the substrate comprises etching through the supporting layer of monocrystalline silicon using a deep reactive ion etching technique.

33. The method of claim 31, further comprising the step of forming a polysilicon hinge that is attached to a back surface of the mirror backing layer and is attached to the electrically conductive layer.

34. The method of claim 33, wherein said step of forming an optically reflective mirror surface comprises evaporating or sputtering a layer of gold onto the front surface of the mirror backing layer.

35. The method of claim 34, further comprising the step of electroplating a layer of nickel onto the back surface of the mirror backing layer.

36. The method of claim 33, wherein said step of forming a polysilicon hinge comprises forming a polysilicon electrostatic clamping electrode that is attached to the back surface of the mirror backing layer and overlaps the groove.

37. The method of claim 30, wherein said step of removing a portion of the substrate is preceded by the step of thermally oxidizing at least one sidewall of the mirror backing layer that is exposed by the groove.

38. The method of claim 34, wherein said step of forming a polysilicon hinge comprises forming a polysilicon electrostatic clamping electrode that is attached to the back surface of the mirror backing layer and overlaps the groove.

39. The method of claim 38, wherein said step of removing a portion of the substrate is preceded by the step of thermally oxidizing at least one sidewall of the mirror backing layer that is exposed by the groove.

40. A method of forming an optoelectronic device, comprising the steps of:

forming a monocrystalline silicon mirror backing layer having a thickness greater than about 10 μ

m, adjacent a first surface of a silicon-on-insulator substrate;

forming a polysilicon hinge that mechanically couples the mirror backing layer to the silicon-on-insulator substrate;

removing a portion of the silicon-on-insulator substrate at a second surface thereof using a deep reactive ion etching technique, to expose a front surface of the mirror backing layer, and

forming an optically reflective mirror surface on the front surface of the mirror backing layer.

41. The method of claim 40, wherein the silicon-on-insulator substrate comprises a monocrystalline silicon conductive layer having a thickness of greater than about 10 μ

m; and

wherein said step of forming a monocrystalline silicon mirror backing layer comprises etching a groove in the monocrystalline silicon conductive layer using a deep reactive ion etching technique.

42. The method of claim 40, wherein said step of forming an optically reflective mirror surface comprises evaporating or sputtering a layer of reflective material onto the front surface of the mirror backing layer.

43. The method of claim 42, wherein the layer of reflective material comprises a material selected from the group consisting of gold and aluminum.

44. The method of claim 43, further comprising the step of electroplating a layer of nickel onto the back surface of the mirror backing layer.

45. The method of claim 40, further comprising the step of electroplating a layer of nickel onto the back surface of the mirror backing layer.

46. The method of claim 41, wherein said step of forming a polysilicon hinge comprises forming a polysilicon electrostatic clamping electrode that is attached to a back surface of the mirror backing layer and overlaps the groove.

47. The method of claim 41, wherein said step of removing a portion of the silicon-on-insulator substrate is preceded by the step of thermally oxidizing at least one sidewall of the mirror backing layer that is exposed by the groove.

48. The method of claim 41, wherein said step of forming an optically reflective mirror surface comprises evaporating or sputtering a layer of reflective material onto the front surface of the mirror backing layer;

and wherein said step of forming a polysilicon hinge comprises forming a polysilicon electrostatic clamping electrode that is attached to a back surface of the mirror backing layer and overlaps the groove.

49. The method of claim 48, wherein said step of removing a portion of the silicon-on-insulator substrate is preceded by the step of thermally oxidizing at least one sidewall of the mirror backing layer that is exposed by the groove.