Nonvolatile semiconductor memory device

Abstract

Abstract PURPOSE:To improve writing characteristics of a nonvolatile semiconductor memory device having a floating electrode, by arranging the end surface of a high melting metal silicide film and the end surface of a polycrystalline silicon film, on the same line. CONSTITUTION:A high melting metal film 2 is made to encroach on the end surface of a resist by isotropic etching, and a polycrystalline silicon film 3 is subjected to isotropic etching to make the end surfaces of the films 3 and 2 in almost vertical form. Since, in the sectional form, the high melting metal silicide film 2 and the polycrystalline silicon film 3 are vertically etched, a contact area between a controlling electrode and a floating electrode is kept large, so that a capacitance C1 between the controlling electrode 2 and the floating electrode 4 becomes large. A voltage VPP applied to the controlling electrode 3 is divided by C and a capacitance C2 whose electrode are the floating electrode 4 and a P-pole silicon substrate 7. A voltage between the electrode 4 and the substrate 7, which determines writing efficiency, becomes large. Therefore electron based on avalanche phenomena generated between source and drain parts becomes easy to be implanted in the floating electrode, and writing characteristics are improved.

Inventors

• 👤 Setsuo Wake

Bibliographic Details