Method for improving roughness of polycrystalline layer of silicon wafer

The invention relates to a method for improving the roughness of a polycrystalline layer of a silicon wafer, and the method comprises the following steps: 1, providing a semiconductor substrate which is a monocrystalline silicon wafer with a proper thickness; 2, growing and forming a polycrystalline silicon layer with a gettering effect on the back surface of the semiconductor substrate by adopting a CVD (Chemical Vapor Deposition) process, wherein the polycrystalline silicon layer is a POLY layer; and 3, growing a thin and compact silicon dioxide layer on the exposed outer surface of the polycrystalline silicon layer through a high-temperature and ultra-short-time film forming method on the surface of the polycrystalline silicon layer with the gettering effect by adopting a rapid heat treatment process, namely an RTP process, so as to isolate an epitaxial atmosphere, thereby preventing the surface roughness of the polycrystalline silicon layer from deteriorating. According to the method, the problem that the