Open Competition 1 - Electronics and Photonics

Continuous Silicon Wafer Manufacturing

Sponsor: Schott Solar, Inc. (formerly ASE Americas Inc.)

• Project Performance Period: 1/15/2003 - 1/14/2006
• Total project (est.): $5,557,100.00
• Requested ATP funds: $1,877,578.00

Only a small portion of the nation's electric power comes from photovoltaic (PV) modules that capture solar energy and convert it to electricity. The most significant barrier to increased use of PV-generated electricity is the high cost of the silicon wafers used to manufacture the photovoltaic cells. Today these wafers are produced in multi-stage batch processes in large facilities. The multi-stage handling costs, labor, and large physical plant significantly increase costs. ASE Americas proposes a large technological leap in wafer production to reduce these costs -- a continuous production method that integrates crystal growing and wafer cutting. The company has developed one key element of the process, a method for growing silicon in ribbon form as a hollow, octagonal tube. The faces of the octagon are laser-cut into silicon wafers with little waste. (In conventional plants, the silicon crystal is grown as a solid cylinder which is cut by saws, and, as a result, nearly half the silicon is wasted as kerf. The existing ASE technology is still a batch process, however, requiring several material handling steps. The ATP project will develop a continuous, fully integrated process from melted feedstock to cut wafers. Major elements include a fiber-optic laser-beam delivery system to cut crystal facets that will service five crystal-growth stations, a collection system to keep dust and debris generated by laser cutting out of the ribbon-silicon melt in the crucible below, and a novel tube-lifting mechanism to permit sequential laser cutting of wafers from the top of the octagonal crystal tubes as they grow. Investments in wafer manufacturing processes are typically directed toward low-risk incremental improvements. This new method promises a high payoff but because of the high risk ASE has been unable to find funding to proceed without ATP support. ASE estimates that this new method will lower manufacturing costs by 45 to 65 percent. This innovative technology will accelerate the growth of PV-related industries, create jobs, and increase PV exports. Cheaper PV modules will encourage greater use of solar power, mitigating air pollution and dependence on foreign oil. PV-generated electricity will help to trim U.S. annual business losses of more than $30 billion caused by power interruptions. Six subcontractors will be engaged to assist in systems design, testing, and evaluation.

For project information:

Dr. Juris Kalejs, (978) 947-5993
jkalejs@asepv.com

ATP Project Manager

Purabi Mazumdar, (301) 975-4891
purabi.mazumdar@nist.gov