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.