Evaluating a Procedure to Align Local Laser Doping and Metallization

We evaluate a procedure that is meant to ensure a highly accurate alignment between laser-doped lines and either screen-printed metal contacts or laser contact openings (LCO) for subsequent galvanic plating of the metal contacts. For both process routes, we prove that the application of the procedure significantly increases the alignment accuracy, discusses potential error sources, and identifies the major challenges for avoiding misalignment. As shown by the presented experiments, the use of screen-printed contacts is challenging for the alignment, since the laser doping process ""needs to foresee"" the screen print. For plated contacts, however, a much more accurate alignment can be achieved, since the LCO process ""can react"" on the previously applied laser-doped pattern. As we demonstrate, we are able to combine 10-mm-wide LCO lines with 36-mm-wide laser-doped lines (while ensuring that the passivation layer is only opened within the laser-doped area).