A method for forming a semiconductor device, includes steps of: providing a substrate; forming a first seal layer over the substrate; forming a second seal layer atop the first seal layer; forming a patterned photoresist layer on the second seal layer; implanting a dopant into the substrate by using the patterned photoresist layer as a mask; executing a first removing process to remove the patterned photoresist layer, wherein the first seal layer has a higher etch rate than that of the second seal layer in the first removing process; and removing the second seal layer after removing the patterned photoresist layer.