Chemical vapor deposition tool and process for fabrication of photovoltaic structures

• US 9,972,740 B2
• Filed: 12/30/2015
• Issued: 05/15/2018
• Est. Priority Date: 06/07/2015
• Status: Active Grant

• Current Assignee: Tesla Inc.
• Original Assignee: Tesla Inc.
• Inventors: Chae, Yongkee, Fu, Jianming
• Primary Examiner(s): Nguyen, Duy T
• Application Number:
  US14/985,143
• Publication Number:
  US 20160359071A1
• Time in Patent Office: 867 Days
• Field of Search: 438 48, 438 57
• 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: H01L 21/67161 characterized by the layout of the process chambers
• CPC Class Codes: H01L 21/67173 in-line arrangement
• CPC Class Codes: H01L 31/02167 for solar cells
• CPC Class Codes: H01L 31/022425 for solar cells
• CPC Class Codes: H01L 31/022466 made of transparent conductive layers, e.g. TCO, ITO layers
• CPC Class Codes: H01L 31/028 including, apart from doping material or other impurities, only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/03529 Shape of the potential jump barrier or surface barrier
• CPC Class Codes: H01L 31/03762 including only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/074 comprising a heterojunction with an element of Group IV of the Periodic Table, e.g. ITO/Si, GaAs/Si or CdTe/Si solar cells
• CPC Class Codes: H01L 31/1804 comprising only elements of Group IV of the Periodic Table
• CPC Class Codes: H01L 31/1868 Passivation
• CPC Class Codes: H01L 31/202 including only elements of Group IV of the Periodic Table
• CPC Class Codes: Y02E 10/547 Monocrystalline silicon PV cells
• CPC Class Codes: Y02E 10/548 Amorphous silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

One embodiment of the present invention can provide a system for fabricating a photovoltaic structure. During fabrication, the system can deposit a first passivation layer on a first side of a Si base layer of the photovoltaic structure using a static chemical vapor deposition process. The static chemical vapor deposition process can be performed inside a first reaction chamber. The system can then transfer the photovoltaic structure from the first reaction chamber to a second reaction chamber without the photovoltaic structure leaving a common vacuum space comprising both reaction chambers, and deposit a second passivation layer on the first passivation layer using an inline chemical vapor deposition process. The inline chemical vapor deposition process can be performed inside the second reaction chamber.

Claims

1. A method for fabricating a photovoltaic structure, comprising:

depositing a first passivation layer on a first side of a Si substrate, which forms a base layer of the photovoltaic structure, using a static chemical vapor deposition process, wherein the static chemical vapor deposition process is performed inside a first reaction chamber;

transferring the Si substrate from the first reaction chamber to a second reaction chamber without the Si substrate leaving a common vacuum space comprising both reaction chambers; and

depositing a second passivation layer on the first passivation layer using an inline chemical vapor deposition process, wherein the inline chemical vapor deposition process is performed inside the second reaction chamber.

2. The method of claim 1, wherein the first passivation layer includes intrinsic hydrogenated amorphous Si having low hydrogen content.

3. The method of claim 2, wherein depositing the first passivation layer involves using silane gas as a precursor.

4. The method of claim 1, wherein the second passivation layer includes intrinsic hydrogenated amorphous Si having high hydrogen content.

5. The method of claim 4, wherein depositing the second passivation layer involves using silane gas and hydrogen gas as precursors.

6. The method of claim 1, wherein the photovoltaic structure remains stationary during the static chemical vapor deposition process.

7. The method of claim 1, wherein the Si substrate continuously moves through the second reaction chamber during the inline chemical vapor deposition process.

8. The method of claim 1, wherein the second chamber is configured to have a continuous flow of processing gases.

9. The method of claim 1, wherein the common vacuum space further comprises a buffer chamber positioned between the first reaction chamber and the second reaction chamber, wherein transferring the Si substrate from the first reaction chamber to the second reaction chamber involves placing the Si substrate into the buffer chamber prior to placing the Si substrate into the second reaction chamber.

10. The method of claim 1, wherein the Si substrate comprises a thin oxide layer on both surfaces, and wherein the thin oxide layer is formed using a wet oxidation process.

11. The method of claim 1, wherein the common vacuum space further comprises a third reaction chamber, and wherein the method further comprises:

transferring the Si substrate from the second reaction chamber to the third reaction chamber without the Si substrate leaving the common vacuum space; and

depositing a heavily doped amorphous Si layer on the second passivation layer using a second inline chemical vapor deposition process performed inside the third reaction chamber.

12. The method of claim 11, wherein the heavily doped amorphous Si is n-type doped, and wherein the second inline chemical vapor deposition process uses silane gas, hydrogen gas, and phosphine gas as precursors.

13. The method of claim 11, wherein the heavily doped amorphous Si is p-type doped, and wherein the second inline chemical vapor deposition process uses silane gas, hydrogen gas, and diborane gas as precursors.