Semiconductor device and manufacturing method thereof

• US 8,629,069 B2
• Filed: 08/01/2008
• Issued: 01/14/2014
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Original Assignee: Semiconductor Energy Laboratory Co., Ltd.
• Inventors: Akimoto, Kengo, Honda, Tatsuya, Sone, Norihito
• Primary Examiner(s): Everhart, Caridad
• Application Number:
  US12/184,401
• Publication Number:
  US 20080308796A1
• Time in Patent Office: 1,992 Days
• Field of Search: 438/796, 438/799, 438/104, 438/479, 257/E21.349, 257/E21.471, 257/E21.129, 257/E21.475, 257/E21.347
• US Class Current: 438/799
• CPC Class Codes: H01L 21/02164 the material being a silicon oxide, e.g. SiO2
• CPC Class Codes: H01L 21/0217 the material being a silicon nitride not containing oxygen, e.g. SixNy or SixByNz H01L21/02126 and H01L21/0214 take precedence
• CPC Class Codes: H01L 21/02178 the material containing aluminium, e.g. Al2O3
• CPC Class Codes: H01L 21/02266 deposition by physical ablation of a target, e.g. sputtering, reactive sputtering, physical vapour deposition or pulsed laser deposition
• CPC Class Codes: H01L 21/02554 Oxides
• CPC Class Codes: H01L 21/02565 Oxide semiconducting materials not being Group 12/16 materials, e.g. ternary compounds
• CPC Class Codes: H01L 21/02631 Physical deposition at reduced pressure, e.g. MBE, sputtering, evaporation
• CPC Class Codes: H01L 21/02667 Crystallisation or recrystallisation of non-monocrystalline semiconductor materials, e.g. regrowth
• CPC Class Codes: H01L 21/428 using electromagnetic radiation, e.g. laser radiation
• CPC Class Codes: H01L 21/465 Chemical or electrical treatment, e.g. electrolytic etching to form insulating layers H01L21/469
• CPC Class Codes: H01L 21/477 Thermal treatment for modifying the properties of semiconductor bodies, e.g. annealing, sintering H01L21/38 - H01L21/449 and H01L21/461 - H01L21/475 take precedence
• CPC Class Codes: H01L 27/1225 with semiconductor materials not belonging to the group IV of the periodic table, e.g. InGaZnO
• CPC Class Codes: H01L 27/1285 using control of the annealing or irradiation parameters, e.g. using different scanning direction or intensity for different transistors
• CPC Class Codes: H01L 29/04 characterised by their crystalline structure, e.g. polycrystalline, cubic or particular orientation of crystalline planes characterised by physical imperfections H01L29/30
• CPC Class Codes: H01L 29/045 by their particular orientation of crystalline planes
• CPC Class Codes: H01L 29/66969 of devices having semiconductor bodies not comprising group 14 or group 13/15 materials comprising selenium or tellurium in uncombined form other than as impurities in semiconductor bodies of other materials, comprising cuprous oxide or cuprous iodide H01L21/02365
• CPC Class Codes: H01L 29/7869 having a semiconductor body comprising an oxide semiconductor material, e.g. zinc oxide, copper aluminium oxide, cadmium stannate
• CPC Class Codes: H01L 29/78693 the semiconducting oxide being amorphous
• CPC Class Codes: H01L 29/78696 characterised by the structure of the channel, e.g. multichannel, transverse or longitudinal shape, length or width, doping structure, or the overlap or alignment between the channel and the gate, the source or the drain, or the contacting structure of the channel H01L29/78612 takes precedence; transistors having a drain offset region or a lightly doped drain [LDD] H01L29/78621

Abstract

An object is to provide a semiconductor device of which a manufacturing process is not complicated and by which cost can be suppressed, by forming a thin film transistor using an oxide semiconductor film typified by zinc oxide, and a manufacturing method thereof. For the semiconductor device, a gate electrode is formed over a substrate; a gate insulating film is formed covering the gate electrode; an oxide semiconductor film is formed over the gate insulating film; and a first conductive film and a second conductive film are formed over the oxide semiconductor film. The oxide semiconductor film has at least a crystallized region in a channel region.

Claims

1. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode; and

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states.

2. The method according to claim 1, wherein the step of heating is performed by using a lamp.

3. The method according to claim 1, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

4. The method according to claim 1, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

5. The method according to claim 1, wherein the step of heating is performed by rapid thermal annealing.

6. The method of according to claim 1, wherein the substrate is a silicon substrate.

7. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film to crystallize at least a portion of the oxide semiconductor film;

forming a source electrode and a drain electrode on the oxide semiconductor film; and

forming a passivation film over at least the oxide semiconductor film and the source electrode and the drain electrode,

wherein each of the source electrode and the drain electrode comprises a titanium film in contact with a surface of the oxide semiconductor film and a second conductive film comprising aluminum or aluminum alloy on the titanium film,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states, and

wherein the step of heating is performed at a temperature of 250 to 570°

C.

8. The method according to claim 7, wherein the heating step is performed by using a lamp.

9. The method according to claim 7, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

10. The method according to claim 7, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

11. The method according to claim 7, wherein the step of heating is performed by rapid thermal annealing.

12. The method according to claim 7, wherein the step of forming the source electrode and the drain electrode on the oxide semiconductor film occurs after the step of heating the oxide semiconductor film.

13. The method of according to claim 7, wherein the substrate is a silicon substrate.

14. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

patterning the oxide semiconductor film; and

heating the patterned oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states.

15. The method according to claim 14, wherein the heating step is performed for 1 minute to 1 hour.

16. The method according to claim 14, wherein the heating step is performed by using a lamp.

17. The method according to claim 14, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

18. The method according to claim 14, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

19. The method according to claim 14, wherein the step of heating is performed by rapid thermal annealing.

20. The method according to claim 14, wherein the oxide semiconductor film further comprises nitrogen.

21. The method of according to claim 14, wherein the substrate is a silicon substrate.

22. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

patterning the oxide semiconductor film;

heating the patterned oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film, and

forming a passivation film over the oxide semiconductor film by sputtering,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states.

23. The method of according to claim 22, wherein the substrate is a silicon substrate.

24. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over, the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

patterning the oxide semiconductor film; and

heating the patterned oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states,

wherein the heating step comprises a preheating state and a main heating state after the preheating, and

wherein a temperature gradient in the main heating state is larger than a temperature gradient in the preheating state.

25. The method of according to claim 24, wherein the substrate is a silicon substrate.

26. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film; and

patterning the oxide semiconductor film after heating the oxide semiconductor film,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states.

27. The method according to claim 26, wherein the heating step is performed for 1 minute to 1 hour.

28. The method according to claim 26, wherein the heating step is performed by using a lamp.

29. The method according to claim 26, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

30. The method according to claim 26, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

31. The method according to claim 26, wherein the step of heating is performed by rapid thermal annealing.

32. The method according to claim 26, wherein the oxide semiconductor film further comprises nitrogen.

33. The method of according to claim 26, wherein the substrate is a silicon substrate.

34. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film;

patterning the oxide semiconductor film after heating the oxide semiconductor film; and

forming a passivation film over the oxide semiconductor film by sputtering,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states.

35. The method according to claim 34, wherein the oxide semiconductor film comprises nitrogen.

36. The method of according to claim 34, wherein the substrate is a silicon substrate.

37. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film; and

patterning the oxide semiconductor film after heating the oxide semiconductor film,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states,

wherein the heating step comprises a preheating state and a main heating state after the preheating, and

wherein a temperature gradient in the main heating state is larger than a temperature gradient in the preheating state.

38. The method of according to claim 37, wherein the substrate is a silicon substrate.

39. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming a first insulating film over the gate electrode;

forming a second insulating film over the first insulating film;

forming an oxide semiconductor film over the gate electrode with the first and second insulating films interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film;

patterning the oxide semiconductor film after heating the oxide semiconductor film; and

forming a passivation film over the oxide semiconductor film by sputtering,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states, and

wherein the first insulating film and the second insulating film are fanned consecutively in the same chamber without breaking a vacuum and under the same temperature.

40. The method according to claim 39, wherein the heating step is performed for 1 minute to 1 hour.

41. The method according to claim 39, wherein the heating step is performed by using a lamp.

42. The method according to claim 39, wherein the oxide semiconductor film is formed by sputtering using at least oxygen gas.

43. The method according to claim 39, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

44. The method according to claim 39, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

45. The method according to claim 39, wherein the heating step comprises a preheating state and a main heating state after the preheating, and

wherein a temperature gradient in the main heating state is larger than a temperature gradient in the preheating state.

46. The method according to claim 39, wherein the step of heating is performed by rapid thermal annealing.

47. The method according to claim 39, wherein the first insulating film is formed by sputtering using at least oxygen gas and wherein the second insulating film is formed by sputtering using at least oxygen gas.

48. The method according to claim 39, wherein the oxide semiconductor film further comprises nitrogen.

49. The method of according to claim 39, wherein the substrate is a silicon substrate.

50. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming a first insulating film comprising silicon nitride over the gate electrode;

forming a second insulating film comprising silicon oxide over the first insulating film;

forming an oxide semiconductor film over the gate electrode with the first and second insulating films interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film;

patterning the oxide semiconductor film after heating the oxide semiconductor film; and

forming a passivation film over the oxide semiconductor film by sputtering,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states, and

wherein the first insulating film and the second insulating film are formed consecutively in the same chamber without breaking a vacuum and under the same temperature.

51. The method according to claim 50, wherein the heating step is performed for 1 minute to 1 hour.

52. The method according to claim 50, wherein the heating step is performed by using a lamp.

53. The method according to claim 50, wherein the oxide semiconductor film is fainted by sputtering using at least oxygen gas.

54. The method according to claim 50, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

55. The method according to claim 50, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

56. The method according to claim 50, wherein the heating step comprises a preheating state and a main heating state after the preheating, and

wherein a temperature gradient in the main heating state is larger than a temperature gradient in the preheating state.

57. The method according to claim 50, wherein the step of heating is performed by rapid thermal annealing.

58. The method according to claim 50, wherein the first insulating film is formed by sputtering using at least oxygen gas and wherein the second insulating film is formed by sputtering using at least oxygen gas.

59. The method of according to claim 50, wherein the substrate is a silicon substrate.

60. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film;

forming a source electrode and a drain electrode on the oxide semiconductor film; and

forming a passivation film over at least the oxide semiconductor film and the source electrode and the drain electrode,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states, and

wherein each of the source electrode and the drain electrode comprises a metal nitride film in contact with a surface of the oxide semiconductor film and a second conductive film comprising aluminum or aluminum alloy on the metal nitride film.

61. The method according to claim 60, wherein the heating step is performed for 1 minute to 1 hour.

62. The method according to claim 60, wherein the heating step is performed by using a lamp.

63. The method according to claim 60, wherein the oxide semiconductor film is formed by sputtering using at least oxygen gas.

64. The method according to claim 60, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

65. The method according to claim 60, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum;

chromium and niobium.

66. The method according to claim 60, wherein the heating step comprises a preheating state and a main heating state after the preheating, and

wherein a temperature gradient in the main heating state is larger than a temperature gradient in the preheating state.

67. The method according to claim 60, wherein the step of heating is performed by rapid thermal annealing.

68. The method according to claim 60, wherein the step of forming the source electrode and the drain electrode on the oxide semiconductor film occurs after the step of heating the oxide semiconductor film.

69. The method according to claim 60, wherein the insulating film is formed by sputtering using at least oxygen gas.

70. The method according to claim 60, wherein the oxide semiconductor film further comprises nitrogen.

71. The method of according to claim 60, wherein the substrate is a silicon substrate.

72. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film by lamp heating to crystallize at least a portion of the oxide semiconductor film; and

patterning the oxide semiconductor film after heating the oxide semiconductor film,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states, and

wherein each of the insulating film and the oxide semiconductor film is formed by sputtering using at least oxygen gas.

73. The method according to claim 72, wherein the heating step is performed for 1 minute to 1 hour.

74. The method according to claim 72, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

75. The method according to claim 72, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

76. The method according to claim 72, wherein the heating step is performed by using a lamp selected from the group consisting of a halogen lamp, a metal halide lamp, a xenon arc lamp, a carbon arc lamp, a high pressure sodium lamp, and a high pressure mercury lamp.

77. The method of according to claim 72, wherein the substrate is a silicon substrate.

78. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode; and

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film,

wherein each of the insulating film and the oxide semiconductor film is formed by sputtering using at least oxygen gas, and

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states.

79. The method according to claim 78, wherein the step of heating is performed by using a lamp.

80. The method according to claim 78, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

81. The method according to claim 78, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

82. The method according to claim 78, wherein the step of heating is performed by rapid thermal annealing.

83. The method according to claim 78, wherein the oxide semiconductor film further comprises nitrogen.

84. The method of according to claim 78, wherein the substrate is a silicon substrate.

85. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film to crystallize at least a portion of the oxide semiconductor film;

forming a source electrode and a drain electrode on the oxide semiconductor film; and

forming a passivation film over at least the oxide semiconductor film and the source electrode and the drain electrode,

wherein each of the source electrode and the drain electrode comprises a titanium film in contact with a surface of the oxide semiconductor film and a second conductive film comprising aluminum or aluminum alloy on the titanium film,

wherein each of the insulating film and the oxide semiconductor film is formed by sputtering using at least oxygen gas,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states, and

wherein the step of heating is performed at a temperature of 250 to 570°

C.

86. The method according to claim 85, wherein the heating step is performed by using a lamp.

87. The method according to claim 85, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

88. The method according to claim 85, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

89. The method according to claim 85, wherein the step of heating is performed by rapid thermal annealing.

90. The method according to claim 85, wherein the step of forming the source electrode and the drain electrode on the oxide semiconductor film occurs after the step of heating the oxide semiconductor film.

91. The method of according to claim 85, wherein the substrate is a silicon substrate.

92. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

patterning the oxide semiconductor film; and

heating the patterned oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film,

wherein the insulating film is formed by sputtering using at least oxygen gas and the oxide semiconductor film is formed by sputtering using at least oxygen gas, and

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states.

93. The method according to claim 92, wherein the heating step is performed for 1 minute to 1 hour.

94. The method according to claim 92, wherein the heating step is performed by using a lamp.

95. The method according to claim 92, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

96. The method according to claim 92, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

97. The method according to claim 92, wherein the step of heating is performed by rapid thermal annealing.

98. The method of according to claim 92, wherein the substrate is a silicon substrate.

99. A method of manufacturing a semiconductor device comprising the steps of:

forming a gate electrode over a substrate;

forming an insulating film over the gate electrode;

forming an oxide semiconductor film over the gate electrode with the insulating film interposed between the oxide semiconductor film and the gate electrode;

heating the oxide semiconductor film at a temperature of 250 to 570°

C. to crystallize at least a portion of the oxide semiconductor film; and

patterning the oxide semiconductor film after heating the oxide semiconductor film,

wherein, after the heating step, the oxide semiconductor film comprises an In—

Ga—

Zn—

O based oxide semiconductor in both amorphous and polycrystalline states, and

wherein the insulating film is formed by sputtering using at least oxygen gas and the oxide semiconductor film is formed by sputtering using at least oxygen gas.

100. The method according to claim 99, wherein the heating step is performed for 1 minute to 1 hour.

101. The method according to claim 99, wherein the heating step is performed by using a lamp.

102. The method according to claim 99, wherein the oxide semiconductor film is heated in an atmosphere comprising oxygen.

103. The method according to claim 99, wherein the gate electrode comprises one selected from the group consisting of tantalum, tungsten, titanium, molybdenum, chromium and niobium.

104. The method according to claim 99, wherein the step of heating is performed by rapid thermal annealing.

105. The method of according to claim 99, wherein the substrate is a silicon substrate.