METHOD AND STRUCTURE FOR HYDROGENATION OF SILICON SUBSTRATES WITH SHAPED COVERS

• US 20080092948A1
• Filed: 09/10/2007
• Published: 04/24/2008
• Est. Priority Date: 09/11/2006
• Status: Active Grant

• Current Assignee: Silicon China (HK) Limited
• Original Assignee: Silicon China (HK) Limited
• Inventors: Ho, Pui, Chan, Yick, Wong, Man, Chan, Chung, Cheung, Nathan
• Granted Patent: US 8,153,887 B2
• Time in Patent Office: Days
• US Class Current: 136/255
• CPC Class Codes: H01L 31/02168 the coatings being antireflective or having enhancing optical properties for the solar cells
• CPC Class Codes: H01L 31/02363 of the semiconductor body itself, e.g. textured active layers
• CPC Class Codes: H01L 31/0352 characterised by their shape or by the shapes, relative sizes or disposition of the semiconductor regions
• CPC Class Codes: H01L 31/04 adapted as photovoltaic [PV] conversion devices testing thereof during manufacture H01L22/00; testing thereof after manufacture H02S50/10
• CPC Class Codes: H01L 31/18 Processes or apparatus specially adapted for the manufacture or treatment of these devices or of parts thereof
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y10T 156/1002 with permanent bending or reshaping or surface deformation of self sustaining lamina

Abstract

Method and structure for hydrogenation of silicon substrates with shaped covers. According to an embodiment, the present invention provides a method for fabricating a photovoltaic material. The method includes providing a semiconductor substrate. The method also includes forming a crystalline material characterized by a plurality of worm hole structures therein overlying the semiconductor substrate. The worm hole structures are characterized by a density distribution from a surface region of the crystalline material to a defined depth within a z-direction of the surface region to form a thickness of material to be detached. The method further includes providing a glue layer overlying a surface region of the crystalline material. The method includes joining the surface region of the crystalline material via the glue layer to a support substrate.

Claims

1. A method for fabricating a photovoltaic material, the method comprising:

providing a semiconductor substrate;

forming a crystalline material characterized by a plurality of worm hole structures therein overlying the semiconductor substrate, the worm hole structures being characterized by a density distribution from a surface region of the crystalline material to a defined depth within a z-direction of the surface region to form a thickness of material to be detached;

providing a glue layer overlying a surface region of the crystalline material;

joining the surface region of the crystalline material via the glue layer to a support substrate;

delaminating a portion of the crystalline material from the semiconductor substrate, while the portion of the thickness of crystalline material remains attached to the support substrate, to cause formation of a surface region from the portion of the thickness of crystalline material; and

forming a cover layer overlaying the thickness of crystalline material, the cover layer including a plurality of light trapping members, the cover layer being characterized by a first effective refractive index, the plurality of light trapping members being shaped in accordance to the first effective refractive index.

2. The method of claim 1 further comprising attaching the cover layer to the semiconductor substrate.

3. The method of claim 1 wherein the forming a cover layer comprises:

depositing a thickness of dielectric material over the thickness of the crystalline material, the thickness of dielectric material being substantially transparent;

forming facets on a top portion of the thickness of the dielectric material.

4. The method of claim 3 wherein the facets include a first facet and a second facet, the first facet and the second facet sharing a wedge, the wedge being associated with a total internal reflection angle.

5. The method of claim 3 wherein the depositing comprises chemical vapor deposition.

6. The method of claim 3 wherein the depositing comprises physical vapor deposition.

7. The method of claim 3 wherein the depositing comprises sputtering.

8. The method of claim 3 wherein the forming facets comprises performing directional etching on the top portion of the thickness of the dielectric material.

9. The method of claim 3 wherein the facets include a first facet and a second facet, the first facet and the second facet sharing a wedged angle for light trapping, the wedged angle being associated with the first effective refractive index.

10. The method of claim 3 wherein the forming wedge facets comprises:

determining at least a first angle for a maximum amount of light trapping,

11. The method of claim 1 wherein the forming a cover layer comprises:

providing a thickness of polymer material;

molding the thickness of polymer material to form wedge facets on a top portion of the thickness of polymer material.

12. The method of claim 1 wherein the forming a cover layer comprises:

providing a thickness of polymer material;

pressing the thickness of polymer material to form wedge factes on a top portion of the thickness of polymer material.

13. The method of claim 1 wherein the forming a cover layer comprises:

providing a thickness of glass material;

shaping a top portion of the thickness of glass material to form wedge facets on a top portion of the thickness of polymer material.

14. The method of claim 1 wherein the cover layer is attached to the substrate by an adhesive.

15. The method of claim 1 wherein the cover layer comprises dielectric material.

16. The method of claim 1 wherein the cover layer comprises polymer material.

17. The method of claim 1 wherein the cover layer comprises glass material.

18. The method of claim 1 wherein the semiconductor substrate comprises silicon.

19. The method of claim 1 wherein the semiconductor substrate comprises single crystal silicon, silicon germanium, gallium arsenide, Group II/VI, or Group III/V materials.

20. The method of claim 1 wherein the forming of the crystalline material characterized by the plurality of worm hole structures comprises electrochemical etching a portion of a thickness of the semiconductor substrate to form the thickness of material to be detached and to form the interface between the thickness of material and the remaining portion of the semiconductor substrate.

21. The method of claim 1 wherein the hydrogen plasma species comprises a plurality of hydrogen particles.

22. The method of claim 1 wherein the delaminating comprises subjecting the portion of the crystalline material to a thermal treatment process.

23. The method of claim 1 wherein the delaminating comprises subjecting the portion of the crystalline material to a mechanical prying process.

24. The method of claim 1 wherein the delaminating comprises subjecting the portion of the crystalline material to electromagnetic radiation.

25. The method of claim 1 wherein the delaminating comprises subjecting the portion of the crystalline material to a chemical process.

26. The method of claim 1 wherein the delaminating comprises subjecting the portion of the crystalline material to an energy to cause the delaminating.

27. The method of claim 1 wherein the glue layer is selected from spin on glass, a eutectic material, a polymer, or a metal layer.

28. The method of claim 1 wherein the worm hole structures comprise a characteristic dimension ranging from about 1 nanometer to about 1 micron.

29. The method of claim 1 wherein the density distribution ranges from about 10/cm³ to about 10²⁰/cm³.

30. The method of claim 1 wherein the density distribution ranges from a first density value at a vicinity of the support structure and a second density at a vicinity of the upper surface region.

31. The method of claim 1 wherein the density distribution ranges from 10/cm³ to 10¹⁰/cm³ at a vicinity of the support structure and 10¹⁰/cm³ to 10²⁰/cm³ at a vicinity of the upper surface region.

32. The method of claim 1 wherein the textured surface region has a roughness ranging from about 10 nanometers to about 10 microns.

33. The method of claim 1 wherein the textured surface region has a surface roughness of greater than about 10 nanometers to cause less than about 25% reflection from a total amount of irradiating in a wavelength ranging from about 0.1 micron to about 5 microns.

34. The method of claim 1 wherein the using comprising forming one or more P type and N type junctions on a portion of the crystalline material.

35. A method for fabricating a photovoltaic material, the method comprising:

providing a semiconductor substrate;

forming a crystalline material characterized by a plurality of worm hole structures therein overlying the semiconductor substrate, the worm hole structures being characterized by a density distribution from a surface region of the crystalline material to a defined depth within a z-direction of the surface region to form a thickness of material to be detached;

subjecting the crystalline material to a hydrogen plasma species to occupy at least one or more of the worm hole structures therein of the crystalline material within a vicinity of an interface between the thickness of material and a remaining portion of the semiconductor substrate, the one or more worm hole structures having respective surface regions;

passivating the surface regions during the subjecting of the hydrogen plasma species to reduce a electron-hole recombination process;

providing a glue layer overlying a surface region of the crystalline material;

joining the surface region of the crystalline material via the glue layer to a support substrate;

delaminating a portion of the crystalline material from the semiconductor substrate, while the portion of the thickness of crystalline material remains attached to the support substrate, to cause formation of a textured surface region from the portion of the thickness of crystalline material;

processing the solar cell structure;

providing a cover structure overlaying the crystalline material, the cover structure includes a plurality of facets on top portion; and

using the overlying thickness of crystalline material having the plurality of worm hole structures on the support substrate for a photovoltaic application.

36. The method of claim 35 wherein the semiconductor substrate comprises silicon.

37. The method of claim 35 wherein the semiconductor substrate comprises single crystal silicon, silicon germanium, gallium arsenide, Group II/VI, or Group III/IV materials.

38. The method of claim 35 wherein the forming of the crystalline material characterized by the plurality of worm hole structures comprises anodizing a portion of a thickness of the semiconductor substrate to form the thickness of material to be detached and to form the interface between the thickness of material and the remaining portion of the semiconductor substrate.

39. The method of claim 35 wherein the portion of the thickness is characterized by a single crystalline material.

40. The method of claim 35 wherein the hydrogen plasma species comprises a plurality of hydrogen particles.

41. The method of claim 35 wherein the delaminating comprises subjecting the portion of the crystalline material to a thermal treatment process.

42. The method of claim 35 wherein the delaminating comprises subjecting the portion of the crystalline material to a mechanical prying process.

43. The method of claim 35 wherein the delaminating comprises subjecting the portion of the crystalline material to electromagnetic radiation.

44. The method of claim 35 wherein the delaminating comprises subjecting the portion of the crystalline material to a chemical process.

45. The method of claim 35 wherein the delaminating comprises subjecting the portion of the crystalline material to an energy to cause the delaminating.

46. The method of claim 35 wherein the glue layer is selected from spin on glass, a eutectic material, a polymer, or a metal layer.

47. The method of claim 35 wherein the worm hole structures comprise a characteristic dimension ranging from about 1 nanometer to about 1 micron.

48. The method of claim 35 wherein the density distribution ranges from about 10/cm³ to about 10²⁰/cm³.

49. The method of claim 35 wherein the density distribution ranges from a first density value at a vicinity of the support structure and a second density at a vicinity of the upper surface region.

50. The method of claim 35 wherein the density distribution ranges from 10/cm³ to 10¹⁰/cm³ at a vicinity of the support structure and 10¹⁰/cm³ to 10²⁰/cm³ at a vicinity of the upper surface region.

51. The method of claim 35 wherein the textured surface region has a roughness ranging from about 10 nanometers to about 10 microns.

52. The method of claim 35 wherein the textured surface region is characterized by a surface roughness to facilitate capture of one or more photons being illuminated thereon.

53. The method of claim 35 wherein the textured surface region has a surface roughness of greater than about 10 nanometers to cause less than about 25% reflection from a total amount of irradiating in a frequency ranging from about 0.1 micron to about 5 microns.

54. The method of claim 35 wherein the using comprising forming one or more P type and N type junctions on a portion of the crystalline material.

55. A photovoltaic device comprising:

a support substrate having a support surface region;

a thickness of crystalline material characterized by a plurality of worm hole structures therein overlying the support surface region of the support substrate, the worm hole structures being characterized by a density distribution, the one or more worm hole structures having respective surface regions, the thickness of crystalline material having an upper surface region;

a passivation material overlying the surface regions to cause a reduction of a electron-hole recombination process;

a glue layer provided between the support surface region and the thickness of crystalline material;

a textured surface region formed overlying from the upper surface region of the thickness of crystalline material; and

a cover structure overlaying the crystalline material, the cover structure includes a plurality of facets on top portion.

56. The device of claim 55 wherein the semiconductor substrate comprises silicon.

57. The device of claim 55 wherein the semiconductor substrate comprises single crystal silicon, silicon germanium, gallium arsenide, Group II/VI, or Group III/V materials.

58. The device of claim 55 wherein the glue layer is selected from spin on glass, a eutectic material, a polymer, or a metal layer.

59. The device of claim 55 wherein the textured surface is characterized by a surface roughness of about 10 nanometers to about 10 microns.

60. The device of claim 55 wherein the textured surface is characterized by a surface roughness of about 10 nanometers and greater.

61. The device of claim 55 wherein the support substrate comprises metallurgical-grade polysilicon.

62. The device of claim 55 wherein the support substrate comprises alloy-grade polysilicon

63. The device of claim 55 wherein the support substrate comprises glass or quartz.

64. The device of claim 55 wherein the support substrate comprises an organic material, a metal material, a dielectric material, or a semiconductor material.

65. The device of claim 55 wherein the thickness of crystalline material is characterized by a thickness of about 1 micron and greater.

66. The device of claim 55 wherein the thickness of crystalline material ranges from about 1 micron to about 100 microns.

67. The device of claim 55 wherein the passivation material comprises hydrogen species.

68. The device of claim 55 wherein the passivation material comprises oxygen, fluorine, bromine, carbon species.

69. The device of claim 55 wherein the density distribution ranges from about 10/cm³ to about 10²⁰/cm³.

70. The device of claim 55 wherein the density distribution ranges from a first density value at a vicinity of the support structure and a second density at a vicinity of the upper surface region.

71. The device of claim 55 wherein the density distribution ranges from 10 atoms/cm³ to 10¹⁰ atoms/cm³ at a vicinity of the support structure and 10¹⁰ atoms/cm³ to 1020 atoms/cm3 at a vicinity of the upper surface region.

72. The device of claim 55 further comprising one or more P type and N type junctions on a portion of the crystalline material.

78. The device of claim 55 wherein the support substrate comprises alloy-grade polysilicon

73. A partially processed semiconductor substrate for manufacturing a solar cell, the substrate comprises:

a support layer, the support layer being characterized by a thickness of at least 150 microns;

a transferring layer overlaying the support layer;

a photovoltaic material overlaying the transferring layer, the photovoltaic material being characterized by a thickness of less than fifty microns, the photovoltaic material including a top region and a bottom region, the top region being characterized by a first impurity type, the bottom side being characterized by a second impurity type, the first impurity type and the second impurity type having opposite polarities.

74. The substrate of claim 73 wherein the bottom region comprises a boron doping.

75. The substrate of claim 73 wherein the bottom region comprises a phosphorus doping.

76. The substrate of claim 73 wherein the bottom region comprises a arsenic doping.

77. The substrate of claim 73 wherein the support layer comprises a metallurgical-grade polysilicon material.

79. The partially processed semiconductor substrate of claim 73 wherein the photovoltaic material comprises worm holes.

80. The partially processed semiconductor substrate of claim 73 wherein the transferring layer comprises spin-on glass material.

81. The partially processed semiconductor substrate of claim 73 wherein the transferring layer comprises polymer material.

82. A method for manufacturing a solar cell, the method comprising:

providing a substrate, the substrate including a support region;

transferring a photovoltaic material overlying the support region of the substrate, the photovoltaic material being characterized by a first thickness, the photovoltaic material including a conducting layer positioned within the first thickness, the first thickness being less than 50 microns, the photovoltaic material including a first side and a second side;

forming an emitter region on the photovoltaic material by a at least diffusion process within a vicinity of the first side, the emitter region being characterized by a first impurity type;

forming a mask overlaying the emitter region, the mask exposing at least a first contact region;

forming the first contact region within a vicinity of the second side of the photovoltaic material;

doping the first contact region with a second impurity type, the second impurity type and the first impurity type being characterized by opposite polarities, the first contact region being electrically coupled to the conducting layer;

removing the mask;

forming a passivation overlaying the first contact region and the photovoltaic material;

forming an anti-reflection coating overlaying the passivation;

forming a pattern using the anti-reflection region for a first opening and a second opening, the first opening being positioned within a vicinity of the first contact region and exposing the first contact region, the second opening being positioned outside the first contact region and exposing the emitter region, the first opening and the second opening facing a substantially similar direction; and

forming a cover structure, the cover structure overlaying the anti-reflection region, the cover structure includes a plurality of facets on a top portion.

83. The method of claim 82 further comprising forming worm holes within the photovoltaic region.

84. The method of claim 82 further comprising attaching the cover structure to the substrate.

85. The method of claim 82 wherein the forming a pattern comprises stripping one or more portion of the anti-reflection region.

87. The method of claim 82 wherein the forming a cover layer comprises:

depositing a thickness of dielectric material over the thickness of the crystalline material, the thickness of dielectric material being substantially transparent;

forming facets on a top portion of the thickness of the dielectric material.

88. The method of claim 87 wherein the facets include a first facet and a second facet, the first facet and the second facet sharing a wedge, the wedge being associated with a total internal reflection angle.

89. The method of claim 87 wherein the depositing comprises chemical vapor deposition.

90. The method of claim 87 wherein the depositing comprises physical vapor deposition.

91. The method of claim 87 wherein the depositing comprises sputtering.

92. The method of claim 87 wherein the forming facets comprises performing directional etching on the top portion of the thickness of the dielectric material.

93. The method of claim 87 wherein the facets include a first facet and a second facet, the first facet and the second facet sharing a wedged angle for light trapping, the wedged angle being associated with the first refractive index.

94. The method of claim 87 wherein the photovoltaic material is characterized by a thickness of less than fifty microns.

95. The method of claim 87 wherein the substrate is characterized by a thickness of approximately 250 microns.

96. The method of claim 87 further comprising forming a glue layer coupling the substrate and photovoltaic material, the glue layer comprising a spin-on-glass.

97. The method of claim 96 wherein the glue layer is characterized by a thickness of between one to ten microns.

98. The method of claim 87 further comprising forming a mirror by depositing refractory metal materials over the substrate.

99. The method of claim 87 wherein the substrate further comprises a mirror overlaying the supporting layer, the mirror comprising a refractory metal material.

86. The method of claim further comprising attaching the cover layer to the semiconductor substrate.