Selective Polysilicon Oxidation Technology for VLSI Isolation

Field isolation technology is described for small geometry VLSI´s in which selective polysilicon oxidation is essential. The technology, also known as SEPOX, offers resist pattern reproducibility in field oxide, while maintaining crystal perfection in the substrate. By a series of experiments, high oxide reliability resulting from a white ribbon-free nature, long lifetime from C-T measurement, and small leakage currents in a reverse biased p-n junction were obtained, as well as a small geometry structure. The feasibility of this technology for MOS LSI´s were examined in a 3-μm rule memory chip, and a reasonable yield and reliability were obtained. The physical limitations of SEPOX were also considered and submicrometer capability was confirmed.