Method of Forming a Substrate Contact for a Bipolar Memory Cell
Original Publication Date: 1985-Apr-01
Included in the Prior Art Database: 2005-Feb-18
This article discloses a method of forming a front-side substrate contact area for a bipolar memory cell. An oxide layer is grown on a substrate by use of differential oxidation techniques. The oxide layer forms a mask which permits boron ions to be implanted into specific areas of the substrate. The boron ions are diffused into the substrate to form a P contact area. The boron implantation is carried out without the need for a separate masking step. The oxidation rate of a semiconductor can be altered by the introduction of dopant ions. As the semiconductor is more heavily doped, its oxidation rate increases. An earlier article [*] discloses an oxide film which is used as a means of preventing ion implantation in selected areas of a semiconductor substrate.