Methods for producing a semiconductor device having planarization films

A method for producing a semiconductor device that has a plurality of first regions in which active regions are formed on a base layer and second regions each provided between the first regions to form device isolation regions, the method comprising:

• a first planarization film formation step of forming, in at least part of a flat portion of the second regions, a first planarization film so as to have a flat surface and a uniform thickness, the entirety of the first planarization film having the flat surface and uniform thickness, such that the surface of the planarization film is planar;
• a second planarization film formation step of forming a second planarization film between the first planarization films to be coplanar with a surface of the first planarization film;
• a peeling layer formation step of forming a peeling layer by ion implantation of a peeling material into the base layer via the first planarization film or the second planarization film;
• and
• a separation step of separating part of the base layer along the peeling layer.