Non-volatile semiconductor storage apparatus and production thereof

Claim 1

A process of producing a non-volatile semiconductor apparatus, comprising steps of: forming an insulation film on a silicon substrate and forming a plurality of perforations in said insulation film; growing silicon using said insulation film as a mask to form a single crystal epitaxial layer in the form of pillars; removing entirely said insulation film to expose a surface of said silicon substrate not covered with said single crystal epitaxial layer; forming, by thermal oxidization, a first gate insulation film over an area encompassing said pillars of the single crystal epitaxial layer and a surface of said silicon substrate not covered with said single crystal epitaxial layer between said pillars; performing deposition and etching back of polycrystalline silicon to form a plurality of floating gates on side faces of said pillars of the single crystal epitaxial layer; implanting an impurity to form a diffusion layer at tops of said pillars of the single crystal epitaxial layer and the surface of said silicon substrate which is not covered with said single crystal silicon layer and said floating gates; forming a second gate insulation film on the surfaces of said floating gates; performing deposition and etching back of polycrystalline silicon to form a plurality of control gates which cover side faces of said floating gates and fill gaps between said pillars of the single crystal epitaxial layer in a direction of a row; and forming a plurality of bit lines for interconnecting said diffusion layer formed at the tops of said pillars of the single crystal epitaxial layer in a direction of a column.