Improved Profile Epitaxial Technique for Electron Shielding
Original Publication Date: 1984-Sep-01
Included in the Prior Art Database: 2005-Feb-05
The interaction of ionizing radiation, such as alpha particles, with an integrated circuit semiconductor substrate results in the production of electrons which can alter the charge storage state of memory devices in the region of the point of incidence of the radiation. It has been reported in the literature that integrated circuits having a buried epitaxial layer 2 of P+ conductivity (NA=1017) in a silicon semiconductor substrate 4 of P conductivity (NA=1015), as shown in Fig. 1, will form an electron shield which will serve to repel electrons produced by ionizing radiation at deeper portions of the semiconductor body. Fig. 2 is a graph showing the variation in concentration for the P type dopant in the substrate 4 and the buried epitaxial layer 2 as a function of the depth below the upper surface of the integrated circuit.