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Process optimization for improving drilling efficiency in EWT solar cell manufacturing

: Pantsar, H.; Eisenbeis, T.; Rekow, M.; Murison, R.; Herfurth, H.; Heinemann, S.

Liu, X. ; Laser Institute of America -LIA-:
ICALEO 2010, 29th International Congress on Applications of Lasers & Electro-Optics. Congress proceedings. CD-ROM : September 26-30, 2010, Anaheim, California, USA
Orlando, Fla.: LIA, 2010 (LIA 613, Vol.103)
ISBN: 978-0-912035-61-1
International Congress on Applications of Lasers & Electro Optics (ICALEO) <29, 2010, Anaheim/Calif.>
Conference Paper
Fraunhofer ILT ()

Pulse parameter optimization is a key element in reaching higher drilling rates in the production of Emitter Wrap Through (EWT) solar cells. Manufacturing of these cells relies on fast laser drilling of silicon wafers. In order to create a cost case for EWT manufacturing, not only the drilling rate, but also the investment costs and cost of ownership have to be taken into account. In this aspect using fewer lower power lasers with a capability to maximize energy efficiency in drilling is an important factor. Master Oscillator Power Amplifier fiber laser concept allows for independent adjustment of pulse width, energy and temporal shape. This capability can be exploited for improving the drilling process efficiency. Combined with a FPGA controller, one can drill holes at unprecedented speeds. It was shown that a single hole can be drilled through a 210 m silicon wafer using less than 3 mJ of energy; consequently 6,250 holes per second could be drilled using 18.2 W laser power. The results were compared to q-switched lasers by mimicking the shape of a high peak power q-switched pulse.