Thin film deposition via a spatially-coordinated and time-synchronized process

• US 20100151149A1
• Filed: 12/12/2008
• Published: 06/17/2010
• Est. Priority Date: 12/12/2008
• Status: Active Grant

• Current Assignee: Ovshinsky Technologies LLC
• Original Assignee: Ovshinsky Innovation, LLC
• Inventors: Ovshinsky, Stanford R.
• Granted Patent: US 8,168,268 B2
• Time in Patent Office: Days
• US Class Current: 427/563
• CPC Class Codes: C23C 16/24 Deposition of silicon only
• CPC Class Codes: C23C 16/452 by activating reactive gas streams before their introduction into the reaction chamber, e.g. by ionisation or addition of reactive species
• CPC Class Codes: C23C 16/455 characterised by the method used for introducing gases into reaction chamber or for modifying gas flows in reaction chamber
• CPC Class Codes: C23C 16/50 using electric discharges generation and control of plasma in discharge tubes for surface treatment H01J37/32, H01J37/34
• CPC Class Codes: H01L 31/202 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H05H 1/42 with provisions for introducing materials into the plasma, e.g. powder, liquid arc stabilising or constricting arrangements H05H1/3405; coaxial protecting fluids H05H1/341; electrostatic spraying, spraying apparatus with means for charging the spray electrically B05B5/00 ; cf. B23K9/324, B05B7/22
• CPC Class Codes: Y02E 10/50 Photovoltaic [PV] energy
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

A deposition system and process for the formation of thin film materials. In one embodiment, the process includes forming an initial plasma from a first material stream and allowing the plasma to evolve in space and/or time to extinguish species that are detrimental to the quality of the thin film material. After the initial plasma evolves to an optimum state, a second material stream is injected into the deposition chamber to form a composite plasma that contains a distribution of species more conducive to formation of a high quality thin film material. The deposition system includes a deposition chamber having a plurality of delivery points for injecting two or more streams (source materials or carrier gases) into a plasma region. The delivery points are staggered in space to permit an upstream plasma formed from a first material stream deposition source material to evolve before combining a downstream material stream with the plasma. Injection of different material streams is also synchronized in time. The net effect of spatial coordination and time synchronization of material streams is a plasma whose distribution of species is optimized for the deposition of a thin film photovoltaic material at high deposition rates. Delivery devices include nozzles and remote plasma sources.

Claims

1. A method of forming a thin film material comprising:

providing a deposition chamber;

said deposition chamber including a substrate, a first cathode, a first anode, a first delivery device, and a second delivery device;

said deposition chamber having a first direction extending from said first cathode to said first anode;

said first delivery device including a first delivery point;

said second delivery device including a second delivery point positioned between said first delivery point and said substrate;

said second delivery point being spatially displaced from said first delivery point in said first direction;

providing a first material stream to said first delivery device, said first delivery device injecting said first material stream into said deposition chamber;

establishing an electric field between said first cathode and said first anode, said electric field initiating a plasma, said plasma comprising species derived from said first material stream; and

providing a second material stream to said second delivery device, said second delivery device injecting said second material stream into said plasma to form a composite plasma, said composite plasma comprising species derived from said first material stream and said second material stream.

2. The method of claim 1, wherein said substrate is positioned on said anode

3. The method of claim 1, wherein said first cathode is a pore cathode.

4. The method of claim 1, wherein said first delivery device comprises a nozzle, said nozzle having an opening at said first delivery point.

5. The method of claim 4, wherein said opening has a cross-sectional dimension of less than 10 μ

m.

6. The method of claim 4, wherein said opening has a cross-sectional dimension of less than 1 μ

m.

7. The method of claim 4, wherein said opening has a cross-sectional dimension of between 0.1 mm and 10 mm.

8. The method of claim 4, wherein said second delivery device comprises a nozzle, said nozzle having an opening at said second delivery point.

9. The method of claim 8, wherein said opening at said second delivery point has a cross-sectional dimension of between 0.1 mm and 10 mm.

10. The method of claim 1, wherein the separation between said first delivery point and said second delivery point in said first direction is greater than or equal to 1 mm.

11. The method of claim 1, wherein the separation between said first delivery point and said second delivery point in said first direction is greater than or equal to 10 mm.

12. The method of claim 1, wherein the separation between said first delivery point and said second delivery point in said first direction is less than 1 mm.

13. The method of claim 1, wherein the separation between said first delivery point and said second delivery point in said first direction is less than 100 μ

m.

14. The method of claim 1, wherein said electric field oscillates at a microwave frequency, radiofrequency, ultrahigh frequency, or very high frequency.

15. The method of claim 1, wherein said first material stream comprises silicon or germanium.

16. The method of claim 15, wherein said first material stream comprises silane, disilane, or germane.

17. The method of claim 15, wherein said first material stream comprises the neutral radical SiH₃ or the neutral radical GeH₃.

18. The method of claim 15, wherein said second material stream comprises silicon or germanium.

19. The method of claim 15, wherein said second material stream comprises fluorine.

20. The method of claim 1, wherein said first material stream comprises fluorine.

21. The method of claim 20, wherein said first material stream comprises a fluorinated form of silane.

22. The method of claim 21, wherein said first material stream comprises SiF₄, SiF₃H, SiF₂H₂, or SiFH₃.

23. The method of claim 1, wherein said first material stream comprises a first metastable species.

24. The method of claim 23, wherein said second material stream comprises a second metastable species.

25. The method of claim 24, wherein the lifetime of said second metastable species is shorter than the lifetime of said first metastable species.

26. The method of claim 1, wherein said first material stream is injected intermittently.

27. The method of claim 26, wherein said second material stream is injected intermittently.

28. The method of claim 26, wherein said first material stream is pulsed periodically into said deposition chamber, said periodic pulsing including alternating on cycles and off cycles, said first material stream being delivered at a first flow rate during said on cycles, said first material stream being delivered at a second flow rate during said off cycles, said first flow rate exceeding said second flow rate.

29. The method of claim 28, wherein said second material stream is injected during said off cycles and not during said on cycles.

30. The method of claim 28, wherein said second flow rate is zero.

31. The method of claim 1, wherein said plasma has a first distribution of species adjacent to said first delivery point and a second distribution of species adjacent to said second delivery point.

32. The method of claim 31, wherein the average lifetime of species in said second distribution differs from the average lifetime of species in said first distribution.

33. The method of claim 32, wherein the average lifetime of species in said second distribution is longer than the average lifetime of species in said first distribution.

34. The method of claim 31, wherein the number density of neutral radicals is higher in said second distribution of species than in said first distribution of species.

35. The method of claim 34, wherein the number density of the neutral radical SiH₃ is higher in said second distribution of species than in said first distribution of species.

36. The method of claim 31, wherein said composite plasma has a first distribution of species adjacent to said second point of delivery and a second distribution of species adjacent to said substrate.

37. The method of claim 36, wherein said second distribution of said composite plasma has a higher number density of neutral radicals than said first distribution of said composite plasma.

38. The method of claim 1, wherein said deposition chamber further includes a third delivery device having a third point of delivery and said method further comprises:

providing a third material stream to said third delivery device, said third delivery device injecting said third stream into said composite plasma to form a second composite plasma.

39. The method of claim 1, wherein said deposition chamber further includes a second cathode and a third delivery device, said third delivery device including a third point of delivery, said method further comprising:

establishing a secondary electric field between said second cathode and said first anode;

said secondary electric field initiating a plasma from said second material stream;

providing a third material stream to said third delivery device, said third delivery device injecting said third material stream into said plasma initiated by said secondary electric field.

40. The method of claim 1, further comprising:

introducing a background gas into said deposition chamber, said plasma further comprising species derived from said background gas.

41. The method of claim 40, wherein said background gas comprises argon, neon, helium, xenon, krypton, hydrogen, or nitrogen.

42. The method of claim 1, wherein said first delivery device is a remote plasma source.

43. The method of claim 42, wherein said second delivery device is a remote plasma source.

44. A method of forming a thin film material comprising:

providing a deposition chamber;

said deposition chamber including a substrate, a cathode, an anode, a first delivery device, and a second delivery device;

said deposition chamber having a first direction extending from said cathode to said anode and a second direction extending from said anode to said substrate;

said first delivery device including a first delivery point positioned between said anode and cathode;

said second delivery device including a second delivery point positioned between said anode and said substrate;

providing a first material stream to said first delivery device, said first delivery device injecting said first material stream between said cathode and said anode;

establishing an electric field between said cathode and said anode, said electric field forming a plasma region between said cathode and said anode, said plasma region comprising a plasma, said plasma including species derived from said first material stream; and

providing a second material stream to said second delivery device, said second delivery device injecting said second material stream between said anode and said substrate.

45. The method of claim 44, wherein said substrate is positioned outside of said plasma region.

46. The method of claim 45, further comprising transporting said species derived from said first material stream toward said substrate, said species exiting said plasma region and deactivating, said second material stream combining with said deactivated species.

47. The method of claim 46, wherein said first material stream comprises silicon.

48. The method of claim 47, wherein said second material stream comprises fluorine.

49. The method of claim 45, wherein said second delivery device is a remote plasma source.

50. The method of claim 44, wherein said deposition chamber further comprises a third delivery device having a third delivery point, said third delivery device staggered from said first delivery device in said first direction, said third delivery point being located between said anode and said cathode, said method further comprising:

providing a third material stream to said third delivery device, said third delivery device injecting said third material stream into said plasma region, said plasma further comprising species derived from said third material stream.

51. The method of claim 50, wherein said first material stream comprises silicon and said third material stream comprises germanium.

52. The method of claim 51, wherein said second material stream comprises fluorine.

53. The method of claim 44, wherein said deposition chamber further comprises a third delivery device having a third delivery point, said third delivery device staggered from said second delivery device in said second direction, said third delivery point being located between said anode and said substrate, said method further comprising:

providing a third material stream to said third delivery device, said third delivery device injecting said third material stream between said anode and said substrate.

54. The method of claim 53, wherein said first material stream comprises silicon and said third material stream comprises fluorine.

55. The method of claim 44, wherein said first cathode is a pore cathode.

56. The method of claim 44, wherein said first delivery device comprises a nozzle, said nozzle having an opening at said first delivery point.

57. The method of claim 56, wherein said opening has a cross-sectional dimension of less than 10 μ

m.

58. The method of claim 56, wherein said opening has a cross-sectional dimension of less than 1 μ

m.

59. The method of claim 56, wherein said opening has a cross-sectional dimension of between 0.1 mm and 10 mm.

60. The method of claim 56, wherein said second delivery device comprises a nozzle, said nozzle having an opening at said second delivery point.

61. The method of claim 60, wherein said opening at said second delivery point has a cross-sectional dimension of between 0.1 mm and 10 mm.

62. The method of claim 44, wherein said electric field oscillates at a microwave frequency, radiofrequency, ultrahigh frequency, or very high frequency.

63. The method of claim 44, wherein said first material stream comprises silicon or germanium.

64. The method of claim 63, wherein said first material stream comprises silane, disilane, or germane.

65. The method of claim 63, wherein said first material stream comprises the neutral radical SiH₃ or the neutral radical GeH₃.

66. The method of claim 63, wherein said second material stream comprises silicon or germanium.

67. The method of claim 63, wherein said second material stream comprises fluorine.

68. The method of claim 44, wherein said first material stream comprises fluorine.

69. The method of claim 68, wherein said first material stream comprises a fluorinated form of silane.

70. The method of claim 69, wherein said first material stream comprises SiF₄, SiF₃H, SiF₂H₂, or SiFH₃.

71. The method of claim 44, wherein said first material stream comprises a first metastable species.

72. The method of claim 71, wherein said second material stream comprises a second metastable species.

73. The method of claim 72, wherein the lifetime of said second metastable species is shorter than the lifetime of said first metastable species.

74. The method of claim 44, wherein said first material stream is injected intermittently.

75. The method of claim 74, wherein said second material stream is injected intermittently.

76. The method of claim 74, wherein said first material stream is pulsed periodically into said deposition chamber, said periodic pulsing including alternating on cycles and off cycles, said first material stream being delivered at a first flow rate during said on cycles, said first material stream being delivered at a second flow rate during said off cycles, said first flow rate exceeding said second flow rate.

77. The method of claim 76, wherein said second material stream is injected during said off cycles and not during said on cycles.

78. The method of claim 76, wherein said second flow rate is zero.

79. A method for forming a thin film material comprising:

providing a deposition chamber, said deposition chamber including a substrate, a first remote plasma source having a first injection point and a first delivery device having a second injection point;

providing a first material stream to said first remote plasma source, said first remote plasma source injecting a plasma comprising said first material stream into said deposition chamber at said first injection point; and

providing a second material stream to said first delivery device, said first delivery device injecting said second material stream into said deposition chamber at said second injection point.

80. The method of claim 79, further comprising forming a thin film on said substrate, said thin film comprising elements derived from said first material stream and said second material stream.

81. The method of claim 79, wherein said first delivery source is a remote plasma source.

82. The method of claim 79, wherein said deposition chamber further includes a second remote plasma source, said method further comprising:

providing a third material stream to said second remote plasma source, said second remote plasma source injecting a plasma comprising said second material stream into said deposition chamber.

83. The method of claim 79, wherein said first delivery device comprises a nozzle, said nozzle having an opening at said second injection point.

84. The method of claim 83, wherein said opening has a cross-sectional dimension of less than 10 μ

m.

85. The method of claim 83, wherein said opening has a cross-sectional dimension of less than 1 μ

m.

86. The method of claim 83, wherein said opening has a cross-sectional dimension of between 0.1 mm and 10 mm.

87. The method of claim 79, wherein the separation between said first injection point and said second injection point is greater than or equal to 1 mm.

88. The method of claim 79, wherein the separation between said first injection point and said second injection point is greater than or equal to 10 mm.

89. The method of claim 79, wherein the separation between said first injection point and said second injection point is less than 10 mm.

90. The method of claim 79, wherein said first material stream comprises silicon or germanium.

91. The method of claim 90, wherein said first material stream comprises silane, disilane, or germane.

92. The method of claim 90, wherein said first material stream comprises the neutral radical SiH₃ or the neutral radical GeH₃.

93. The method of claim 90, wherein said second material stream comprises silicon or germanium.

94. The method of claim 90, wherein said second material stream comprises fluorine.

95. The method of claim 79, wherein said first material stream comprises fluorine.

96. The method of claim 95, wherein said first material stream comprises a fluorinated form of silane.

97. The method of claim 96, wherein said first material stream comprises SiF₄, SiF₃H, SiF₂H₂, or SiFH₃.

98. The method of claim 79, wherein said first material stream comprises a first metastable species.

99. The method of claim 98, wherein said second material stream comprises a second metastable species.

100. The method of claim 99, wherein the lifetime of said second metastable species is shorter than the lifetime of said first metastable species.

101. The method of claim 79, wherein said first material stream is injected intermittently.

102. The method of claim 101, wherein said second material stream is injected intermittently.

103. The method of claim 101, wherein said first material stream is pulsed periodically into said deposition chamber, said periodic pulsing including alternating on cycles and off cycles, said first material stream being delivered at a first flow rate during said on cycles, said first material stream being delivered at a second flow rate during said off cycles, said first flow rate exceeding said second flow rate.

104. The method of claim 103, wherein said second material stream is injected during said off cycles and not during said on cycles.

105. The method of claim 103, wherein said second flow rate is zero.

106. The method of claim 79, wherein the number density of neutral radicals is higher adjacent to said substrate than adjacent to said first or second injection point.

107. The method of claim 106, wherein said neutral radicals include SiH₃.

108. The method of claim 79, wherein said neutral radicals include a fluorinated radical.

109. A method of forming a thin film material comprising:

providing a deposition chamber;

said deposition chamber including a substrate, a first cathode, a second cathode, a first anode, a first delivery device, and a second delivery device;

said first delivery device including a first delivery point positioned between said first cathode and said first anode;

said second delivery device including a second delivery point positioned between said second cathode and said first anode;

establishing a first electric field between said first cathode and said first anode;

establishing a second electric field between said second cathode and said first anode;

providing a first material stream to said first delivery device, said first delivery device injecting said first material stream into said first electric field, said first electric field forming a plasma from said first material stream; and

providing a second material stream to said second delivery device, said second delivery device injecting said second material stream into said second electric field, said second electric field forming a plasma from said second material stream.

110. The method of claim 109, wherein said first electric field and said second electric field are at least partially non-overlapping in space.

111. The method of claim 109, further comprising forming a thin film material on said substrate, said thin film material comprising elements derived from said first material stream and said second material stream.

112. A method of forming a thin film material comprising:

providing a deposition chamber;

said deposition chamber including a substrate, a first cathode, a first anode, and a first delivery device;

said first delivery device including a first delivery point;

establishing an electric field between said first cathode and said first anode; and

providing a first material stream to said first delivery device, said first delivery device intermittently injecting said first material stream into said electric field, said electric field forming a plasma, said plasma comprising species from said first material stream.

113. The method of claim 112, wherein said substrate is positioned on said anode

114. The method of claim 112, wherein said first cathode is a pore cathode.

115. The method of claim 112, wherein said first delivery device comprises a nozzle, said nozzle having an opening at said first delivery point.

116. The method of claim 115, wherein said opening has a cross-sectional dimension of less than 10 μ

m.

117. The method of claim 115, wherein said opening has a cross-sectional dimension of less than 1 μ

m.

118. The method of claim 115, wherein said opening at said second delivery point has a cross-sectional dimension of between 0.1 mm and 10 mm.

119. The method of claim 112, wherein said electric field oscillates at a microwave frequency, radiofrequency, ultrahigh frequency, or very high frequency.

120. The method of claim 112, wherein said first material stream comprises silicon or germanium.

121. The method of claim 120, wherein said first material stream comprises silane, disilane, or germane.

122. The method of claim 120, wherein said first material stream comprises the neutral radical SiH₃ or the neutral radical GeH₃.

123. The method of claim 112, wherein said first material stream comprises fluorine.

124. The method of claim 123, wherein said first material stream comprises a fluorinated form of silane.

125. The method of claim 124, wherein said first material stream comprises SiF₄, SiF₃H, SiF₂H₂, or SiFH₃.

126. The method of claim 112, wherein said first material stream comprises a first metastable species.

127. The method of claim 112, wherein said first material stream is pulsed periodically into said deposition chamber, said periodic pulsing including alternating on cycles and off cycles, said first material stream being delivered at a first flow rate during said on cycles, said first material stream being delivered at a second flow rate during said off cycles, said first flow rate exceeding said second flow rate.

128. The method of claim 127, wherein said second material stream is injected during said off cycles and not during said on cycles.

129. The method of claim 127, wherein said second flow rate is zero.

130. The method of claim 112, further comprising:

introducing a background gas into said deposition chamber, said plasma further comprising species derived from said background gas.

131. The method of claim 130, wherein said background gas comprises argon, neon, helium, xenon, krypton, hydrogen, or nitrogen.

132. The method of claim 112, wherein said first delivery device is a remote plasma source.

133. The method of claim 132, wherein said electric field has zero strength.