Manufacturing method for semiconductor device having a T type gate electrode

A semiconductor device manufacturing method for manufacturing a semiconductor device having a T type gate electrode, the method comprising steps of:

• forming a lower gate electrode of said T type gate electrode on a semiconductor substrate;
• sequentially forming a first insulating film and a second insulating film on said lower gate electrode, forming said first insulating film to be thicker than said lower gate electrode and to leave a difference in height around said lower gate electrode, and forming said second insulating film to have such a thickness as to flatten a difference in height near said lower gate electrode;
• selectively removing said second insulating film by an etch back method until said first insulating film located on an upper surface of said lower gate electrode is exposed;
• selectively removing said first insulating film located on the upper surface of said lower gate electrode until the upper surface of said lower gate electrode is exposed;
• forming an upper gate electrode of said T type gate electrode in a space from which said first insulating film is removed;
• and
• forming said first insulating film to be thinner than said T type gate electrode by etching back using a dry etching method on a whole surface thereof after the step of forming said first insulating film to be thicker than said T type gate electrode, and wherein said second insulating film is formed thereafter.