Investigation On Oxygen Precipitation And Induced-Defect In Heavily Arsenic Doped Silicon

Recently, the N/N+ and P/P+ epitaxial structures have been applied in the study and production of microwave transistor and Ultra-Large-Scale Integrated Circuits (ULSI), and the memorial maintain time of dynamic random access memory can be improved, latch-up effect and soft-error induced by a particles can be resolved through the combination of epitaxy and IG. Heavily As-doped silicon substrates are adopted by many device manufactories because of higher As-doping density. Therefore, quantitative determination of oxygen precipitation and induced-defects in heavily As-doped silicon is important to the realization of IG.The dependence of oxygen precipitation and induced-defects in heavily As-doped silicon on heat treatment process was studied by annealing and IG process, chemical etching, scanning electron micrograph (SEM) and transmission electron microscopy(TEM). A developed IG technique was suggested and the mechanism of the influence of As on oxygen precipitation formation in heavily As-doped silicon was discussed.The nucleation temperature of oxygen precipitation is about 750 C in lightly doped CZSi, while the nucleation in heavily As-doped Si occurred at a higher temperature (750-900 C). The experimental results showed that high density of oxygen precipitation and induced-defects were formed after annealing of wafers at moderate and high temperatures. Both the size and density of oxygen precipitation increase with the annealing time, and the size of oxygen precipitation decrease with the increase of the annealing temperature. TEM showed that the faults and dislocation loops introduced by the oxygen precipitation were formed when the wafers were annealed at moderate temperature, and polyhedral oxygen precipitation was generated at high temperature. A modified IG process was suggested, through which a wider denuded-zone (DZ)on the surface of wafers and higher density of oxygen precipitation in silicon bulk were obtained. It is assumed that As enhances the out-diffusion of oxygen atoms near the surface of Si wafers. IG effect is also gained in heavily B-, P- and Sb-doped Si wafers respectively.