Laser patterning of metal electrode film with optical-induced etching.

A laser patterning was achieved for integrated-type amorphous silicon (a-Si) solar cell submodules with large area, for example a size of 40 cm × 120 cm. For further improvement in the selectivity for YAG laser patterning of metal electrode of integrated-type a-Si solar cell submodules, a new patterning technique has been developed based on the ArF excimer laserinduced patterning. This paper describes some experiments with laser patterning of metal film with optical-induced etching. In order to achieve good selective patterning for Al electrode, Laser Pre-etched Photochemical Etching (LPPE) method has been developed. First, the surface of Al is denatured in BCl3 atmosphere by a convergent beam of ArF excimer laser. Next, a non-convergent beam is used to etch only the denatured Al portion. It decreases the heat affecting the a-Si and improves selectivity. It was confirmed that excimer laser-induced patterning was very useful for patterning of metal electrode in a-Si solar cells.