MULTI-THICKNESS LAYERS FOR MEMS AND MASK-SAVING SEQUENCE FOR SAME

• US 20100079847A1
• Filed: 09/30/2008
• Published: 04/01/2010
• Est. Priority Date: 09/30/2008
• Status: Active Grant

• Current Assignee: Snaptrack Incorporated (Qualcomm, Inc.)
• Original Assignee: Qualcomm MEMS Technologies Incorporated (Qualcomm, Inc.)
• Inventors: Patel, Sapna, Zhong, Fan
• Granted Patent: US 7,719,754 B2
• Time in Patent Office: Days
• US Class Current: 359/290
• CPC Class Codes: B81B 2201/042 Micromirrors, not used as optical switches
• CPC Class Codes: B81B 2203/0315 Cavities
• CPC Class Codes: B81C 1/00476 removing a sacrificial layer B81C1/00912 takes precedence
• CPC Class Codes: G02B 26/0841 the reflecting element being moved or deformed by electrostatic means

Abstract

In various embodiments described herein, methods for forming a plurality of microelectromechanical systems (MEMS) devices on a substrate are described. The MEMS devices comprise x number of different sacrificial or mechanical structures with x number of different sacrificial structure thicknesses or mechanical structure stiffnesses and wherein the x number of sacrificial or mechanical structures are formed by x-1 depositions and x-1 masks.

Claims

1. A method for forming at least a first microelectromechanical systems (MEMS) device, a second MEMS device, and a third MEMS device, in a first region, a second region, and a third region, respectively, the method comprising:

providing a substrate in a reaction chamber;

depositing a first sacrificial layer onto the first, second and third regions of the substrate;

patterning and etching the first sacrificial layer by removing the first sacrificial layer from the second region, while keeping the first sacrificial layer on the first and third regions;

depositing a second sacrificial layer onto the first, second and third regions of the substrate; and

patterning and etching the second sacrificial layer by removing the second sacrificial layer from the third region, while keeping the second sacrificial layer on the first and second regions.

2. The method of claim 1, fuither comprising removing any remaining material of the first and second sacrificial layers from the first, second, and third regions to define MEMS cavities of three different sizes.

3. The method of claim 1, further comprising depositing a third sacrificial layer onto the first, second, and third regions of the substrate and patterning and etching the third sacrificial layer by removing the third sacrificial layer from at least one of the first, second, and third regions.

4. The method of claim 1, wherein the first and second sacrificial layers comprise at least one of molybdenum and amorphous silicon.

5. The method of claim 1, further comprising depositing a thin film etch stop layer prior to at least one of depositing a first sacrificial layer and depositing a second sacrificial layer, wherein the thin film etch stop inhibits etching a layer underlying at least one of the first sacrificial layer and the second sacrificial layer.

6. The method of claim 5, wherein the etch stop layer is between about 100 Å

and 1000 Å

.

7. The method of claim 5, wherein patterning and etching comprises etching with XeF₂.

8. The method of claim 5, wherein the thin film etch stop layer comprises silicon nitride.

9. The method of claim 5, wherein the thin film etch stop layer comprises at least one of Al, Cr, and Ni.

10. The method of claim 5, further comprising removing the thin film etch stop layer simultaneously with the sacrificial layers.

11. The method of claim 1, wherein the first region has a first thickness, the second region has a second thickness, and the third region has a third thickness, wherein the first, second, and third thicknesses correspond to the summation of the thicknesses of at least one of the first and second sacrificial layers and etch stop layer in the first, second, and third regions, and wherein the first thickness produces a second order blue color in an open state, the second thickness produces a first order green color in an open state, and the third thickness produces a first order red color in an open state.

12. The method of claim 1, wherein the first sacrificial layer has a first thickness and the second sacrificial layer has a second thickness and wherein the first and second thicknesses are different.

13. (canceled)

14. (canceled)

15. (canceled)

16. (canceled)

17. (canceled)

18. (canceled)

19. (canceled)

20. (canceled)

21. (canceled)

22. (canceled)

23. (canceled)

24. A method of forming x number of different microelectromechanical systems (MEMS) structures on x regions of a substrate using x-1 depositions and x-1 masks wherein each of the x number of MEMS structures has a unique characteristic, wherein each characteristic corresponds to at least one of a first material and a second material, the method comprising:

depositing the first material onto the substrate;

patterning and etching the first material by removing the first material from at least one region of the substrate;

depositing an etch stop layer over the first material;

depositing the second material over the etch stop layer; and

patterning and etching the second material by removing the second material from at least one different region of the substrate,

wherein x is greater than or equal to 3.

25. The method of claim 24, wherein the first material is different than the second material.

26. The method of claim 24, wherein the first material is the same as the second material.

27. The method of claim 26, wherein the first material and the second material have different thicknesses.

29. The method of claim 24, wherein the first material and the second material comprise at least one material characteristic, wherein the material characteristic is chosen from a group consisting of thickness, stiffness, stress, resistance to etching, conductivity, and resistivity.

30. The method of claim 29, wherein at least one material characteristic of the first material differs from at least one material characteristic of the second material.

37. The method of claim 24, wherein the x number of different MEMS structures comprise x number of different sacrificial structures having x number of different sacrificial structure thicknesses and wherein the x number of sacrificial structures are formed by x-1 sacrificial layer depositions and x-1 masks.

38. The method of claim 24, wherein the x number of different MEMS structures comprise x number of mechanical structures having x number of mechanical structure stiffnesses and wherein forming the x number of mechanical structures comprises:

depositing x-1 mechanical layers; and

conducting x-1 mask steps.

28. (canceled)

31. A method of forming x number of different microelectromechanical systems (MEMS) structures on x regions of a substrate using x-1 depositions and x-1 masks wherein each of the x number of MEMS structures has a unique characteristic, wherein each characteristic corresponds to at least one of a first material and a second material, the method comprising:

depositing the first material onto the substrate;

patterning and etching the first material by removing the first material from at least one region of the substrate;

depositing the second material onto the substrate; and

patterning and etching the second material by removing the second material from at least one different region of the substrate,

wherein at least one of the first and second material comprises a dielectric material and wherein x is greater than or equal to 3.

32. The method of claim 31, wherein the dielectric material is chosen from a group consisting of SiN, SiON_x, and SiO₂.

33. The method of claim 31, wherein the x number of MEMS structures comprise at least a first, second, and third MEMS device in a first, second, and third region and wherein patterning and etching the first material comprises removing the first material from the second region, while keeping the first material on the first and third regions.

34. The method of claim 33, wherein patterning and etching the second material comprises removing the second material from the third region, while keeping the second material on the first and second regions.

35. The method of claim 34, further comprising depositing an etch stop layer after depositing the first material and the second material, wherein the etch stop layer is chosen from a group consisting of SiN_x and Al₂O₃.

36. The method of claim 34, wherein the first, second, and third MEMS devices are each configured to reflect a different color in an unactuated state.

39. A method of forming x number of different microelectromechanical systems (MEMS) structures on x regions of a substrate using x-1 depositions and x-1 masks wherein each of the x number of MEMS structures has a unique characteristic, wherein each characteristic corresponds to at least one of a first material and a second material, the method comprising:

depositing the first material onto the substrate;

patterning and etching the first material by removing the first material from at least one region of the substrate;

depositing the second material onto the substrate; and

patterning and etching the second material by removing the second material from at least one different region of the substrate,

wherein the x number of different MEMS structures comprise x number of different optical stacks having x number of different optical stack thicknesses and wherein x is greater than or equal to 3.

40. A method for forming at least a first microelectromechanical systems (MEMS) device, a second MEMS device, and a third MEMS device in a first region, a second region, and a third region, respectively, the method comprising:

providing a substrate in a reaction chamber;

depositing a first mechanical layer onto the first, second, and third regions of the substrate;

patterning and etching the first mechanical layer by removing the first mechanical layer from the second region, while keeping the first mechanical layer on the first and third regions;

depositing a second mechanical layer onto the first, second and third regions of the substrate; and

patterning and etching the second mechanical layer by removing the second mechanical layer from the first region, while keeping the second mechanical layer on the second and third regions.

41. The method of claim 40, wherein the first mechanical layer comprises a first mechanical layer thickness and the second mechanical layer comprises a second mechanical layer thickness, wherein the first mechanical layer thickness differs from the second mechanical layer thickness.

42. The method of claim 40, wherein the first mechanical layer comprises a first mechanical layer material and the second mechanical layer comprises a second mechanical layer material, wherein the first mechanical layer material differs from the second mechanical layer material.

43. The method of claim 40, wherein the first mechanical layer comprises a first mechanical layer stiffness and the second mechanical layer comprises a second mechanical layer stiffness, wherein the first mechanical layer stiffness differs from the second mechanical layer stiffness.

44. The method of claim 40, wherein the first and the second mechanical layers comprise at least one of Ni and Cr.

45. The method of claim 40, further comprising depositing an etch stop layer, wherein the etch stop layer comprises at least one of Al, Cr, and Ni.

46. The method of claim 40, wherein the first, second, and third MEMS devices each produce a different color in an open state.

47. The method of claim 46, wherein the first, second, and third MEMS devices produce a second order blue color, a first order green color, and a first order red color.