MEMS device made of transition metal-dielectric oxide materials

• US 20030036215A1
• Filed: 07/17/2002
• Published: 02/20/2003
• Est. Priority Date: 07/20/2001
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Reflectivity, Inc. (Texas Instruments, Inc.)
• Inventors: Reid, Jason S.
• Granted Patent: US 7,057,251 B2
• Time in Patent Office: Days
• US Class Current: 438/52
• CPC Class Codes: B81B 2201/045 Optical switches
• CPC Class Codes: B81B 2203/0118 Cantilevers
• CPC Class Codes: B81B 3/0078 Constitution or structural means for improving mechanical properties not provided for in B81B3/007 - B81B3/0075

Abstract

Micromechanical devices are provided that are capable of movement due to a flexible portion. The micromechanical device can have a flexible portion formed of an oxide of preferably an element from groups 3A to 6A of the periodic table (preferably from the first two rows of these groups) and a late transition metal (preferably from groups 8B or 1B of the periodic table). The micromechanical devices can be any device, particularly MEMS sensors or actuators preferably having a flexible portion such as an accelerometer, DC relay or RF switch, optical cross connect or optical switch, or a micromirror part of an array for direct view and projection displays. The flexible portion is preferably formed by sputtering a target having a group 8B or 1B element and a selected group 3A to 6A element, namely B, Al, In, Si, Ge, Sn, or Pb. The target can have other major constituents or impurities (e.g. additional group 3A to 6A element(s)). The target is reactively sputtered in a oxygen ambient so as to result in a sputtered hinge. It is possible to form both stiff and/or flexible portions of the micromechanical device in this way.

Claims

1. A micromechanical device having at least a portion comprising an alloy of an oxide compound and a late transition metal, wherein the oxide compound is in the form of a matrix surrounding discrete late transition metal islands.

2. The micromechanical device of claim 1, wherein the oxide compound is an oxide of silicon, boron or aluminum.

3. The micromechanical device of claim 2, wherein the oxide compound is a silicon oxide or aluminum oxide.

4. The micromechanical device of claim 1, wherein the late transition metal is selected from the groups 8B or 1B of the periodic table.

5. The micromechanical device of claim 1, wherein the late transition metal is a ferromagnetic metal.

6. The micromechanical device of claim 1, which is a MEMS sensor or actuator.

7. The micromechanical device of claim 1, wherein the late transition metal is a noble metal.

8. The micromechanical device of claim 1, wherein the late transition metal is Pd, Pt, or Au.

9. The micromechanical device of claim 1, wherein the oxide comprises less than 0.3 at % nitrogen.

10. The micromechanical device of claim 1, wherein the oxide is an oxynitride that comprises up to 10 at % nitrogen.

11. The micromechanical device of claim 1, wherein at least a flexible portion comprises the oxide compound and the late transition metal.

12. The micromechanical device of claim 1, comprising a substrate, a movable element formed in or on the substrate and a hinge for allowing movement of the movable element relative to the substrate.

13. The micromechanical device of claim 12, wherein the substrate is a semiconductor or light transmissive substrate.

14. The micromechanical device of claim 12, wherein the movable element and/or the hinge are formed of the oxide compound and the late transition metal.

15. The micromechanical device of claim 14, further comprising posts or walls for connecting the movable element to the substrate via the hinge.

16. The micromechanical device of claim 12, wherein the hinge is a sputtered or co-sputtered hinge.

17. The micromechanical device of claim 12, wherein the device is a micromirror device with said movable element having a reflective layer thereon or therein.

18. The micromechanical device of claim 12, which is a sensor.

19. The micromechanical device of claim 17, wherein the reflective layer comprises Al, Ti or Au.

20. The micromechanical device of claim 17, wherein the micromirror device is a light beam steering device.

21. The micromechanical device of claim 17, wherein the light beam steering device is within an optical switch.

22. The micromechanical device of claim 17, wherein the micromirror device is part of a micromirror array in a display.

23. The micromechanical device of claim 22, wherein the display is a direct view or projection display.

24. A micromechanical device selected from a micromirror, a MEMS switch and a MEMS sensor, having a movable portion and a flexible portion, wherein at least one of the movable portion and flexible portion comprise a ceramic compound and a late transition metal, wherein the ceramic compound forms a matrix surrounding discrete late transition metal islands.

25. The micromechanical device of claim 24, wherein the ceramic compound and late transition metal are within the same film or layer.

26. The micromechanical device of claim 25, wherein the film or layer is a ternary or higher system deposited by chemical or physical vapor deposition.

27. A method of making a micromechanical device, comprising:

providing a substrate;

providing a sacrificial layer on the substrate;

providing a structural element on the sacrificial layer;

providing a flexible element for connecting the structural element directly or indirectly to the substrate, wherein the structural element and/or the flexible element of the MEMS device comprises an oxide compound matrix surrounding a late transition metal; and

removing the sacrificial layer so that the structural element is free to move via the flexible element relative to the substrate.

28. The method of claim 27, wherein the substrate is a glass and/or silicon wafer.

29. The method of claim 28, wherein the sacrificial layer comprises silicon or an organic material.

30. The method of claim 28, wherein the MEMS device is a mirror element.

31. The method of claim 28, wherein the mirror element is deposited and patterned on a sacrificial amorphous silicon layer.

32. The method of claim 30, wherein the flexible element and/or structural element is sputtered or co-sputtered, followed by etching.

33. The method of claim 30, wherein the MEMS device comprises a reflective and conductive portion.

34. The method of claim 27, wherein a plurality of individual flexible portions are formed.

35. The method of claim 27, wherein the hinge is formed by an ion beam or discharge directed at a target comprising a transition metal and Si, B or Al.

36. The method of claim 27, wherein the hinge is formed by co-sputtering separate transition metal and Si, B, or Al targets.

37. The method of claim 35, wherein the flexible element and/or structural element formation is in an atmosphere of a noble gas and oxygen.

38. The method of claim 30, wherein the late transition metal is a noble metal.

39. The method of claim 30, wherein the late transition metal is a ferromagnetic metal.

40. The method of claim 39, wherein the MEMS device is a beam steering device in an optical switch.

41. The method of claim 39, wherein the structural element is a micromirror that is part of any array of micromirrors formed at the same time for an optical switch or a direct view or projection display.

42. The method of claim 27, wherein the hinge is nearly or fully saturated with oxygen.

43. The method of claim 42, wherein the hinge comprises particles of late transition metals or late transition metal silicides or borides interspersed within the oxide compound.

44. The method of claim 43, wherein the dielectric is an oxide of silicon, boron or aluminum.

45. The method of claim 44, wherein the transition metal forms from 10 to 80 atomic percent of the material formed and the elements of the oxide compound each range from 20 to 65 atomic percent.

46. The method of claim 27, wherein the ultimate tensile yield strength of the material of the MEMS device is greater than 1 GPa.

47. The method of claim 27, wherein the mirror element is formed before, at the same time, or after, forming the hinge.

48. The method of claim 27, further comprising annealing the MEMS device before or after removing the sacrificial layer.

49. The method of claim 27, wherein the structural element and/or flexible element are reactively sputtered or co-sputtered films formed by reactive sputtering in an oxygen-containing atmosphere.

50. The method of claim 49, wherein the sputtering is in from 10 to 90% oxygen atmosphere.

51. The method of claim 27, wherein the structural and/or flexible elements have from 10 to 60 atomic % oxygen.

52. The method of claim 51, wherein the structural and/or flexible elements are sputtered from a target comprised of from about 15 to 85% late transition metal and from about 85 to 15% silicon.

53. The method of claim 52, wherein the structural and/or flexible elements are sputtered from a target comprised of about 20 to 80% late transition metal and from about 80 to 20% silicon.

54. The method of claim 27, wherein the target comprises at least one late transition metal and at least silicon, boron, or aluminum.

55. The method of claim 54 where the target contains up to 6 at. % impurities from groups 3A through 7A in addition to the transition metal and silicon.

56. The method of claim 51, wherein the structural and/or flexible elements have a long range order of less than 100A.

57. A micromechanical device comprising a late transition metal formed by chemical or physical vapor deposition.

58. The micromechanical device of claim 57, wherein the late transition metal is selected from groups 8B or 1B of the periodic table.

59. The micromechanical device of claim 57, further comprising an element from B, Al, In, Si, Ge, Sn, and Pb.

60. The micromechanical device of claim 59, wherein nitrogen is added to the film.

61. A method for forming a micromechanical device, comprising:

providing a substrate;

depositing a sacrificial layer;

forming one or more additional layers which define the micromechanical device at least in part; and

removing the sacrificial layer;

wherein the one or more additional layers are formed by sputtering a target, the target having at least two elements, one being selected from groups 8B or 1B of the periodic table, and another being selected from groups 3A to 6A of the periodic table, wherein the element selected from groups 3A to 6A is in the form of a matrix surrounding discrete areas comprising the element selected from groups 8B or 1B.

62. The method of claim 61, wherein the sputtering is reactive sputtering in an atmosphere of oxygen and/or nitrogen.

63. The method of claim 62, wherein the atmosphere is entirely or almost entirely oxygen.

64. A micromechanical device comprising a layer formed of one or more oxide compounds in a matrix surrounding a late transition metal.

65. The micromechanical device of claim 64, wherein the material is a substantially homogenous multiphase composite.

66. The micromechanical device of claim 64, wherein the material is disposed at least in an area of the device capable of flexing.

67. The micromechanical device of claim 64, wherein the material is amorphous.

68. The micromechanical device of claim 64, wherein the material has a long range order of less than 100A.

69. The micromechanical device of claim 64, wherein the material comprises an oxide or element selected from the late transition metals and an oxide of a group 3A or 4A element.

70. The micromechanical device of claim 69, wherein the oxide of the group 3A or 4A element is an oxide of selected elements from group 3A or 4A.

71. The micromechanical device of claim 70, wherein the oxide of group 3A or 4A element comprises an oxide of boron, aluminum or silicon.

72. The micromechanical device of claim 70, wherein the oxide of the group 3A or 4A element comprises an oxide of indium, tin, germanium and/or lead.

73. The micromechanical device of claim 69, wherein the oxide or element selected from the late transition metals is an oxide or element selected from Fe, Co or Ni.

74. The micromechanical device of claim 69, wherein the oxide or element selected from the late transition metals is an oxide or element selected from Ru, Rh, Pd, Pt, Ir, Os, Ag or Au.

75. The micromechanical device of claim 69, wherein the oxide or element selected from the late transition metals is a conductive oxide.

76. The micromechanical device of claim 69, wherein the late transition metal is Ru, Rh, Ir or Os.

77. The micromechanical device of claim 76, wherein the late transition metal is Ru or Ir.

78. The micromechanical device of claim 69, wherein the material comprises a late transition metal that forms an oxide.

79. The micromechanical device of claim 69, wherein the material comprises a late transition metal that does not form an oxide.

80. The micromechanical device of claim 69, wherein the material comprises an oxide of Al, Si or B and a late transition metal that does not form an oxide

81. The micromechanical device of claim 69, wherein the material comprises an oxide of In, Sn, TI and/or Pb, and an oxide of Ru, Rh, Os or Ir.

82. The micromechanical device of claim 81, wherein the material has a long range order of less than 100A.

83. The micromechanical device of claim 80, wherein the late transition metal is Pd, Pt, or Au.

84. The micromechanical device of claim 73, wherein the late transition metal is Co.

85. The micromechanical device of claim 84, wherein the oxide from group 3A or 4A is an oxide of silicon or aluminum.

86. The micromechanical device of claim 64, wherein the material is a sputtered material.

87. A method of making a micromechanical device, comprising:

providing a substrate;

providing a sacrificial layer on the substrate;

providing a structural element on the sacrificial layer;

providing a flexible element for connecting the structural element directly or indirectly to the substrate, wherein the structural element and/or the flexible element of the MEMS device comprises an oxide compound and a late transition metal selected from Fe, Co and Ni; and

removing the sacrificial layer so that the structural element is free to move via the flexible element relative to the substrate.

88. A method for forming a micromechanical device, comprising:

providing a substrate;

depositing a sacrificial layer;

forming one or more additional layers which define the micromechanical device at least in part; and

removing the sacrificial layer;

wherein the one or more additional layers are formed by sputtering a target, the target having at least two elements, one being selected from Fe, Co and Ni, and another being selected from groups 3A to 6A of the periodic table.

89. A micromechanical device selected from a micromirror, a MEMS switch and a MEMS sensor, having a movable portion and a flexible portion, wherein at least one of the movable portion and flexible portion comprise a combined ceramic compound and a late transition metal, wherein the combined ceramic compound and late transition metal have a long range order of less than 25 angstroms.

90. A method of making a micromechanical device, comprising:

providing a substrate;

providing a sacrificial layer on the substrate;

providing a structural element on the sacrificial layer;

providing a flexible element for connecting the structural element directly or indirectly to the substrate, wherein the structural element and/or the flexible element of the MEMS device comprises an oxide compound and a late transition that have a long range order of-less than 25 angstroms; and

removing the sacrificial layer so that the structural element is free to move via the flexible element relative to the substrate.

91. A method for forming a micromechanical device, comprising:

providing a substrate;

depositing a sacrificial layer;

forming one or more additional layers which define the micromechanical device at least in part; and

removing the sacrificial layer;

wherein the one or more additional layers are formed by sputtering a target, the target having at least two elements, one being selected a late transition metal, and another being selected from groups 3A to 6A of the periodic table which forms a compound during sputtering, the one or more additional layers comprising a mixed late transition metal and compound of a group 3A to 6A element and which has a long range order of less than 25 angstroms.

92. A micromechanical device comprising a layer formed of one or more oxide compounds and a late transition metal which together have a long range order of less than 25 angstroms.

93. A micromechanical device having at least a portion comprising an oxide compound and a late transition metal that have a long range order of less than 25 angstroms.