| 摘要 |
PROBLEM TO BE SOLVED: To improve anisotropic property of a plasma auxiliary etching method and minimize a data holding loss, by depositing a layer of silicon nitride on silicon oxide and eliminating the silicon nitride layer from the surface of the silicon oxide perpendicularly to the etching direction. SOLUTION: In anisotropical chemical etching of silicon oxide having an etching direction, a layer 17 of silicon nitride is deposited on a thin film 11 of silicon dioxide which is formed in an annealing process, before a photolithograph process in which a source line is determined. The layer 17 of silicon nitride is eliminated in one etching direction from the surface of the thin film 11 of silicon dioxide, perpendicularly to the etching direction, by anisotropically chemical etching or break through. The thin film 11 of silicon dioxide is eliminated perpendicularly in the etching direction. As a result, the thin film 11 of silicon dioxide can be maintained on a side wall of a layer of poly-1 and a tunnel oxide 13 can be maintained in a bottom part of a gate laminated layer, so that improvement in anisotropic property of a plasma auxiliary etching method and minimization of a data holding loss are enabled.
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