High-ramp industrial firing processes for the metallization of crystalline silicon solar cells

Rapid firing of screen-printed metallization is a critical step in the manufacture of crystalline silicon solar cells. Improved cell results are obtained with rapid heat-up and cool-down but optimum conditions have not yet been determined due to the limitations of conventional firing furnaces in achieving high ramp rates. We report results of solar cells processed by several firing profiles. Changes in solar cell parameters were observed as small changes were made to the firing profiles. Changes in cell parameters are correlated to the physical structure of the fired contacts, for both front silver and backside aluminum, as determined by optical microscopy and SEM analysis of wafer cross sections.