Abstract: A semiconductor manufacturing method which comprises the steps of forming a polycrystalline silicon layer on a semiconductor substrate; depositing a silicon oxide layer on the polycrystalline silicon layer; mounting an acidproof layer on the silicon oxide layer; selectively eliminating the acidproof layer deposited on a semiconductor element-isolating region by the photoetching process; selectively eliminating the silicon oxide layer with the retained acidproof layer used as a mask; ion implanting a channel stopper impurity in the semiconductor substrate through the masks formed of a photoresist coated on the acidproof layer the acidproof layer, and silicon oxide layer; eliminating the photoresist; selectively depositing a silicon layer on the exposed polycrystalline silicon; carrying out thermal oxidation with the acidproof layer used as a mask; eliminating the acidproof layer; filling an oxide in the cavities of the side walls of the semiconductor element-isolating insulation layer; and exposing by etching

Abstract: A method of manufacturing a semiconductor substrate, and, in particular, a technique of electrically isolating a semiconductor element formed on a semiconductor substrate. The method comprises the steps of depositing a silicon oxide layer on the surface of a silicon substrate, for its protection; forming a silicon nitride layer on the silicon oxide layer; selectively eliminating the silicon nitride layer; oxidizing the silicon substrate, with the retained silicon nitride layer being used as a mask, thereby providing an oxide layer; depositing a polycrystalline silicon layer on the oxide layer and the retained acid-resisting layer; oxidizing the polycrystalline silicon layer to provide an insulation layer; eliminating the insulation layer until the silicon nitride layer is exposed; and removing all the silicon nitride layer.

Abstract: A method of manufacturing a nonvolatile semiconductor memory device having a gate oxide layer including a relatively thin silicon dioxide layer. This gate oxide layer including the thin silicon dioxide layer is formed by the steps of forming the gate oxide film on a semiconductor element region in a silicon substrate; removing a portion of the gate oxide film to expose a portion of the silicon substrate; implanting impurity ions in the exposed portion of the substrate to an extent that a peak concentration of the impurity ions exceeds a solid solution limit at a temperature of the following thermal annealing step; activating the implanted impurity by thermal annealing so as to form a high impurity concentration layer and thermally oxidizing a surface of the high impurity concentration layer to form the thin silicon dioxide layer.