Semiconductor device with composite surface insulator

Claim 1

A semiconductor device, comprising: a substrate; a capacitor formed in said substrate and having first and second insulation layers and a conductive layer, said first insulation layer being on at least a portion of a surface of said substrate, including a peripheral portion of said capacitor, said second insulation layer being a dielectric material of said capacitor and having a thickness less than that of said first insulation layer, and the conductive layer being on the second insulation layer; drain and source layers in first and second portions of the substrate not covered by either said first insulation layer or said second insulation layer; a third insulation layer on a third portion of the substrate between the first and second portions of the substrate; and a gate layer on the third insulation layer; wherein said first insulation layer comprises a lower layer and an upper layer, said upper layer comprising a silicon nitride film.