Impact of laser hole drilling on the breakage rate of multicrystalline silicon wafers

We have studied the effect of laser hole drilling on the breakage rate of multicrystalline silicon (mc-Si) wafers, with the objective of investigating the production cost of metal wrap-through (MWT) solar cells. Wafers were grouped according to the number of holes (0, 100, and 300), and the breakage force was measured by a plate-twist apparatus. Failure analysis shows that, while the wafers with holes are weaker after the laser drilling, the fracture strength is restored after a standard HF-HNO 3 wet etch.