PURPOSE: To obtain the titled device with an insulation of a nitride film formed only on the surface of a groove by a method wherein a capacitor insulation film is formed of a substance difference from that of the flat part, in an 1-transistor- 1-capacitor type MOS dynamic memory.
CONSTITUTION: The capacitor insulation film is partly formed of a nitride film and an SiO2 film. the nitride film is not left on an Si substrate at the region scheduled for MOS transistor formation, but a complete oxide film is formed. For its manufacture, first a thick field oxide film 32 is formed on the P type Si substrate 31, and a thin SiO2 film 33 is formed on this substrate. Next, the groove 34 e.g. of 1μm width is dug by etching. Then, a nitride film 35 is formed only on the surface of the groove 34 by the method of thermal nitriding, the first layer poly Si 36 being grown over the entire surface, and an oxide film 37 being then formed by oxidation of the surface. The oxide film 33 on the region scheduled for transistor formation, poly Si 36, and oxide film 37 are removed by etching, and accordingly the surface of the substrate is exposed. When an oxide film 38 serving as a gate oxide film is formed, an oxide film 38a is formed on the side part of the first layer poly Si, and a thick oxide 38b on the poly Si. Finally, an Al wiring layer 42 is formed.
NAKANO TOMIO
SATOU KIMIAKI
