Optical evaluation of laser generated plating seed layers

The Laser Transfer and Firing (LTF) process can be used for the creation of seed layers for electroplated front side metallization of silicon solar cells. In this contribution, an optical method to determine the coverage and the diameter of the transferred seed layers is developed and a parameter called optical fill factor is introduced. The optical method is confirmed by EDS measurements. For the transfer, NiV layers with different layer thicknesses were used for the laser transfer and their corresponding thresholds were deduced. A correlation between layer thickness, metal coverage and diameter is observed. Thus, a better understanding of the laser transfer process is achieved.