Method of dynamic temperature control during microcrystalline SI growth

• US 7,687,300 B2
• Filed: 10/22/2007
• Issued: 03/30/2010
• Est. Priority Date: 10/22/2007
• Status: Expired due to Fees

• Current Assignee: Applied Materials Incorporated
• Original Assignee: Applied Materials Incorporated
• Inventors: Choi, Soo Young, Chae, Yong Kee
• Primary Examiner(s): Nguyen; Ha Tran T
• Assistant Examiner(s): PATHAK, SHANTANU
• Application Number:
  US11/876,130
• Publication Number:
  US 20090105873A1
• Time in Patent Office: 890 Days
• Field of Search: None
• US Class Current: 438/57
• CPC Class Codes: C23C 16/24 Deposition of silicon only
• CPC Class Codes: C23C 16/46 characterised by the method used for heating the substrate C23C16/48, C23C16/50 take precedence
• CPC Class Codes: H01L 31/1824 Special manufacturing methods for microcrystalline Si, uc-Si
• CPC Class Codes: Y02E 10/545 Microcrystalline silicon PV cells
• CPC Class Codes: Y02P 70/50 Manufacturing or production processes characterised by the final manufactured product

Abstract

The present invention generally comprises a method for dynamically controlling the temperature of a solar cell substrate during microcrystalline silicon deposition. In amorphous silicon/microcrystalline tandem solar cells, microcrystalline silicon may be deposited using a higher power density and to a greater thickness than amorphous silicon. The higher the power density applied, the faster the deposition may occur, but the temperature of the deposition may also increase. At high temperatures, the likelihood of dopant diffusing into the intrinsic layer of the solar cell and damaging the cell is greater. By dynamically controlling the temperature of the susceptor, the substrate and hence, the dopant can be maintained at a substantially constant temperature below the value at which the dopant may diffuse into the intrinsic layer. The dynamic temperature control permits the microcrystalline silicon to be deposited at a high power density without damaging the solar cell.

Claims

1. A solar cell formation method, comprising:

heating a susceptor to a first temperature and a substrate to a second temperature by providing a heat output to the susceptor;

reducing the heat output to the susceptor to lower the temperature of the susceptor to a third temperature while maintaining the substrate at the second temperature;

reducing the heat output to the susceptor while increasing a cooling output to the susceptor to lower the temperature of the susceptor to a fourth temperature and while maintaining the substrate at the second temperature; and

providing a substantially constant cooling output to the susceptor to substantially maintain the susceptor at the fourth temperature while maintaining the substrate at the second temperature.

2. The method of claim 1, wherein the cooling output is substantially zero during the reducing to the third temperature.

3. The method of claim 1, wherein the heating output is substantially zero during the providing a substantially constant cooling output.

4. The method of claim 1, further comprising:

depositing a microcrystalline silicon layer over a substrate disposed on the susceptor.

5. The method of claim 4, wherein the microcrystalline silicon layer is deposited over an amorphous silicon layer deposited over the substrate.