Plane polishing method of silicon wafer and processing method of silicon wafer

Abstract

The disclosure provides a plane polishing method and a processing method of the silicon wafer. The plane polishing method includes steps of: depositing a hard mask on a silicon substrate to form a silicon wafer base material; forming an opening on the hard mask by photolithography or etching; carrying out an oxidation reaction on a portion of the silicon substrate exposed by the opening, forming an oxide layer having a bottom embedded in the silicon substrate and a top protruding and exposed outside the hard mask by oxidizing the silicon substrate; and polishing the oxide layer by chemical mechanical planarization. In the present disclosure, the surface formed by the oxide layer and the hard mask flat is flat, without a recess even in the case of large structures, thereby precisely controlling a shape and a depth of the cavity in accordance with an oxidation rate on a silicon substrate.