Abstract: Provided are an epitaxial structure and a semiconductor chip applying same. The epitaxial structure comprises a quantum well structure, a P-type contact layer, and an electrode layer, which are stacked in sequence; the P-type contact layer comprises a first step part and a second step part that are disposed in a step shape, the second step part being closer to the quantum well structure relative to the first step part; the first step part and the second step part are filled with a first insulation part. By means of the described method, the anti-catastrophic optical mirror damage value of a semiconductor chip can be effectively improved.

Abstract: Disclosed in the present invention are a laser chip and a preparation method therefor.

Abstract: The present application provides an alignment method for backside photolithography process of the wafer, the alignment method includes: cutting the wafer, and using at least two edges formed by cutting as the first alignment mark; bonding the front side of the wafer to the wafer pad to form a composite wafer; aligning the first alignment mark with the corresponding second alignment mark on the photomask for backside photolithography. This method is not limited by wafer thickness and material, and reduces the secondary input of the photolithography equipment; meanwhile, the probability of fragments of thin wafers in the photolithography process can be reduced, and the yield of the product is effectively improved.