MOSFET with one or several insulating films - where ion implantation is used for increasing etching grade of at least one insulating film

摘要

The insulating film(s) cannot be normally etching by hydrofluoric acid, or only with great difficulty. The ion implantation provides a higher etching grade and enables structuring of the semiconductor substrate by this acid. The insulating films is typically of silicon nitride and the ions used for implantation are of phosphorus. The films may be formed by a silicon dioxide coated with the silicon nitride. An implanation mask of a photolacquer may be deposited over the silicon nitride film. The phosphorus ion implantation is carried out in such a manner as to enable structuring by hydrofluoric acid at room temp.