Patent ID: 6727144
Filing Date: 2004-04-27
Classification: H01L

Abstract:
A manufacturing method for a semiconductor storage device with a floating gate, comprising:a first step for etching a poly-silicon film by using a silicon nitride film having an opening as a mask thereby to form a tapered portion that provides the floating gate later; a second step for depositing a first thermally-oxidized film on the poly-silicon film of the opening of the silicon nitride film; a third step for forming a first NSG film spacer covering the tapered portion of the poly-silicon film on a side wall of the opening of the silicon nitride film; a fourth step for adding heat treatment to the first NSG film spacer to turn it into a denser film; a fifth step for forming a second NSG film spacer on the inner side of the first NSG film spacer; a sixth step for forming a poly-silicon plug to fill the opening of the silicon nitride film, then depositing a second thermally-oxidized film on the poly-silicon plug; a seventh step for removing only the silicon nitride film; an eighth step for etching the poly-silicon film by using the first NSG film spacer, the second NSG film spacer, and the second thermally-oxidized film as the masks; and a ninth step for removing the first NSG film spacer.