The present invention relates to a method of manufacturing a semiconductor device. This method is suited for use, for example, in a method of manufacturing a semiconductor device having a trench portion.
There is a semiconductor device having an element isolation structure obtained by forming an insulating film in a trench portion formed in the surface, as a main surface, of a semiconductor substrate. There is another semiconductor device having an element isolation structure (deep trench isolation: DTI) obtained by forming an insulating film in a trench portion having an aspect ratio greater than 1. The term “aspect ratio” means a ratio of the depth of the trench portion to the width of the trench portion.
Japanese Unexamined Patent Application Publication No. 2011-66067 (Patent Document 1) discloses a method of manufacturing a semiconductor device including a step of forming, in the main surface of a semiconductor substrate, a trench that surrounds therewith an element in plan view and a step of forming an insulating film on the element and in the trench. In the technology described in Patent Document 1, the insulating film is formed so as to cover the upper portion of the element and at the same time forming a space in the trench.