Process for forming an output circuit device for a charge transfer

Abstract

An output circuit device for detecting and converting signal charge transferred thereto from a charge transfer section of a CCD into a signal voltage and a method of forming same. A first diffusion region is formed by diffusing into the semiconductor body a low concentration of an impurity having a conduction type opposite to that of said semiconductor body and having a high diffusion coefficient. A second diffusion region is formed by diffusing into an upper surface portion of the first diffusion region, and in self-alignment therewith, a high concentration of an impurity having a low diffusion coefficient. A third diffusion region is formed by diffusing into the first and second diffusion regions, and in self-alignment therewith, a high concentration of an impurity having a high diffusion coefficient, such that the third diffusion region extends from a surface of said semiconductor body through said first and second diffusion regions to beneath the first diffusion region. A wiring line is formed on the semiconductor body such that the first, second and third diffusion regions lie beneath the wiring line. The high and low diffusion coefficients are high and low relative to one another, and the high and low concentrations are high and low relative to one another.