Abstract: A process is described for manufacturing integrated insulated-gate field-effect transistors comprising contacts on both the source region and the drain region which are self-aligned with respect to the gate electrode. In this process the gate area and the areas of the aforementioned regions are defined by means of an oxidation masking layer, and on these regions by employing the oxidation masking layer, there are produced insulator layers which are relatively thick compared to the gate insulator layer.

Abstract: A monolithic integrated circuit is formed having semiconductor components disposed in surface regions of a semiconductor body, said regions being electrically isolated from the remaining semiconductor body by a pn-junction plane. The regions into which the semiconductor components are formed are electrically isolated by heavily doping surface areas of a substrate with phosphorus, antimony and/or arsenic impurities which are of the opposite conductivity from the substrate. After said doping, an epitaxial layer having a conductivity opposite to that of the substrate is formed over the entire substrate surface with a doping concentration lower than that of the substrate so that during subsequent high temperature processing steps, the substrate impurity out-diffuses into the epitaxial layer and the phosphorus of the heavily doped surface areas diffuses downwardly into the substrate to form a step-like pn-junction surface alternately extending into the substrate and into the epitaxial layer.

Abstract: This relates to a method of producing a monolithic integrated I.sup.2 L circuit including a bipolar analog circuit part. In order to realize good current gain values in the I.sup.2 L transistors as well as high collector breakdown voltages in the analog circuit part, the base zone of the analog circuit part is prediffused prior to diffusion of the I.sup.2 L base and injector regions. After such prediffusion, excessive doping material from the diffusion masking layer is removed and simultaneously windows in the diffusion mask over the I.sup.2 L base and injector regions are opened. Next, doping material having a lower concentration than that which was used for the prediffusion of the analog base region is prediffused into the exposed regions of the substrate. This results in an expanded prediffused base region in the analog circuit part.