Nonvolatile semiconductor memory device and manufacture thereof

Abstract

Abstract PURPOSE:To microminiaturize a storage cell by oxidizing an unnecessary part of the polycrystalline Si film of a first layer, patterning the floating gate of a memory cell, simultaneously forming an element isolating film in a self alignment manner, and forming a floating gate in the middle part of the channel width direction. CONSTITUTION:Polycrystalline Si 14 is stacked on a gate oxide film 131 on a P-type Si 11, a mask 19 of Si3N4 is stacked, and an element isolating oxide film 12 is formed. The mask 19 is removed, the oxide film 13 is eliminated, and the polycrystalline Si 11 covered with oxide films 132, 133 by thermal oxidation. Polycrystalline Si 15 for a control gate is stacked, and control gates 151-154 for each memory cell and gate electrodes 155, 156 of selection transistors are formed. At this time, polycrystalline Si 14 is patterned and separated in the channel length direction, thereby forming independent floating gates 141-144 for each memory cell. By using the gate electrodes as masks, an N-type source.drain 16 is formed and covered with an insulating film 17. An N<+> type layer is formed in one of the N-type layer 16 by opening a window, and an Al bit line 18 is formed. Since mask deviation does not exist, characteristics of a memory cell are improved and microminiaturization is realized.

Inventors

• 👤 Yoshihisa Iwata
• 👤 佳久 岩田

Bibliographic Details