Method for preparing silicon wafer with rough surface and silicon wafer

A method for preparing a silicon wafer with a rough surface, comprising:

• forming a substrate, wherein the substrate has a first region, a second region, and a third region along a first direction, and the first direction is perpendicular to a thickness direction of the substrate;
• depositing a first silicon layer on a surface of the substrate in the second region;
• depositing a dielectric layer on the surface of the substrate in the first region and the third region and on a surface of the first silicon layer facing away from the substrate;
• performing planar planarization on the dielectric layer to expose the first silicon layer and form a dielectric planar layer and a first silicon planar layer;
• depositing a first film layer on a side of the first silicon planar layer facing away from the substrate, wherein the first film layer is made of a material comprising amorphous silicon;
• and
• blanket etching the first film layer to remove the first film layer.