A method for bonding semiconductor substrates includes placing a die on a substrate and performing a heating process on the die and the substrate to bond the respective first connectors with the respective second connectors. Respective first connectors of a plurality of first connectors on the die contact respective second connectors of a plurality of second connectors on the substrate. The heating process includes placing a mask between a laser generator and the substrate and performing a laser shot. The mask includes a masking layer and a transparent layer. Portions of the masking layer are opaque. The laser passes through a first gap in the masking layer and through the transparent layer to heat a first portion of a top side of the die opposite the substrate.