Semiconductor memory and its production process

A process for producing a semiconductor memory comprising the steps of:

• forming at least one island-like semiconductor layer on a semiconductor substrate;
• forming a sidewall of a first insulating film on a sidewall of the island-like semiconductor layer;
• further etching the semiconductor layer using the sidewall as a mask to form an island-like semiconductor layer having cross-sectional areas in a direction horizontal to the semiconductor substrate which areas vary stepwise;
• forming a single-layered or multi-layered insulating film and a first conductive film on the island-like semiconductor layer;
• and
• forming the first conductive film into a sidewall form on a sidewall of the island-like semiconductor layer with intervention of the insulating film, thereby separating the first conductive film,
• whereby a semiconductor memory is produced which has at least one memory cell constituted of the island-like semiconductor layer, a charge storage layer and a control gate, the charge storage layer and the control gate being formed to entirely or partially encircle the sidewall of the island-like semiconductor layer.