PURPOSE: To provide a method for the manufacture of semiconductor devices which improves polishing accuracy.

CONSTITUTION: Dry etching is performed on a semiconductor substrate 1, composed of single-crystal silicon, to etch part thereof. At that time etching grooves 4a and 4b for monitoring are also formed by dry etching. An oxide film insulating layer 2 and 2' is formed on the etched surface, and further the surface thereof is coated with a supporting body layer 3 of polycrystalline silicon or the like. In a polishing process for the semiconductor substrate 1, polishing operation is stopped at the level of a line L where the bottom faces 5a and 5b of the etching grooves 4a and 4b for monitoring are exposed.