Field-effect transistor structure in multilevel polycrystalline silicon

Claim 1

A field-effect transistor device comprising a semiconductor body, the first layer being doped with conductivity-determining impurity at a first level to function as a conductor, conductive means connected to the first layer to apply bias voltage thereto, a second layer of crystalline silicon on said face overlying at least part of the first layer and insulated therefrom by a thin insulating layer of thickness such that the voltage on the first layer significantly influences conduction in the second level through said thin insulating layer, the second level including a part which is closely adjacent and overlying the first level and which is doped with conductivity-determining impurity at a second level which is less than said first level to function as an element having more impedence than said first level, and regions connected to opposite ends of said part and containing conductivity-determining impurity to render the regions more highly conductive than said part.