Esd-protected thin film capacitor structures

Abstract

A thin film protected capacitor structure having a thin film capacitor and a protection device is provided on an integrated circuit wafer. The wafer has a low resistivity substrate of a first type disposed under an epitaxial layer of a second type different from the first type. The structure includes a first heavily doped region, which is of the first type, in and through the epitaxial layer, and an oxide layer having a first oxide region disposed above the first heavily doped region. The first heavily doped region and the low resistivity substrate form the first plate of the thin film capacitor. There is also included a metal layer disposed above the first oxide region. A portion of this metal layer forms the second plate of the thin film capacitor. Between the second plate and the first plate, the aforementioned first oxide region represents the insulating dielectric. There is also included a second heavily doped region in the epitaxial layer. This second heavily doped region, being of the first type and in electrical contact with the metal layer, has a thickness that is less than the thickness of the epitaxial layer. The protection device is formed from this second heavily doped region, the epitaxial layer, and the low resistivity substrate.