Abstract: A programmable read-only-memory (PROM) element is disclosed in which an N-type epitaxial layer, grown on a P-type substrate with an N+ buried layer therebetween, has a P-type anode region formed in a surface portion thereof. An N-type poly-silicon layer is formed on the surface of the anode region, generally within an aperture in an insulating layer, with the dopant of the poly-silicon layer being diffused downwardly into the anode region to form a shallow N-type cathode region. A metal layer is deposited on the surface of the poly-silicon layer over the anode region, and a low resistivity path is provided to the buried layer. To program the memory element, a positive potential is applied to the metal layer relative to the buried layer to break down the barrier between the cathode and anode regions. As the reverse current flow heats the poly-silicon, the metal alloys through the poly-silicon and the cathode region, and shorts to the anode region.

Abstract: In the fabrication of semiconductor devices, a method is provided which includes the steps of selectively doping a semiconductor substrate of one conductivity type to form therein discrete regions of opposite conductivity type, followed by selective epitaxial growth to fill the windows of the diffusion mask, whereby the epitaxially grown regions are inherently characterized by exact alignment with the doped regions. The self-aligned epitaxial structure is then subjected to further processing in accordance with numerous alternate schemes to provide a wide variety of devices.