Isolation for high density integrated circuits

Abstract

An integrated circuit structure having substrate contacts formed as a part of the isolation structure and method for making the same is described. The integrated circuit structure is composed of a monocrystalline silicon body having a pattern of dielectric isolation surrounding regions of the monocrystalline silicon in the body. The dielectric isolation pattern includes a recessed dielectric portion at and just below the surface of the integrated circuit and a deep portion which extends from the side of the recessed dielectric portion opposite to that portion at the surface of said body into the monocrystalline silicon body. A highly doped polycrystalline silicon substrate contact is located within the deep portion of the pattern of isolation. At certain locations the deep portion of the pattern extends to the surface of the silicon body where interconnection metallurgy can electrically contact the polycrystalline silicon so as to form a substrate contact to the bottom of the deep portion of the isolation where the contact electrically connects to the silicon body. Any of a variety of integrated circuit device structures may be incorporated within the monocrystalline silicon regions. These devices include bipolar transistors, field effect transistors, capacitors, diodes, resistors and the like.