Effects Of Rapid Thermal Process On Defects In Czochralski Silicon

With the ever-smaller feature size of integrated circuits (ICs) and the ever-larger size of silicon wafer, defects and impurities in silicon are playing more and more important roles in IC manufacturing. This also puts more stringent requirements on internal gettering (IG) capability of Czochralski silicon (Cz) wafers based on oxygen precipitates and induced defects used for ICs.In this thesis, the effect of the rapid thermal process in nitrogen on oxygen precipitation and the status of in-diffused nitrogen in CZ silicon has been investigated. Furthermore, the effect of RTP on oxide induced stacking faults in nitrogen doped CZ silicon has also been discussed. The most important results achieved in this work have been listed below.(1) Effect of high temperature RTP treatment in nitrogen on silicon properties has been investigated by SIMS and FTIR test. With RTP at 1250℃in nitrogen for 90s, high concentration (> 1016cm-3) of nitrogen could be injected in to silicon. The in-diffused nitrogen could not be detected by FTIR but SIMS. Moreover, the injected nitrogen could combine with oxygen to form N-0 complex in the following annealing, which could be detected by FTIR.(2) A new intrinsic gettering process has developed based on RTP in nitrogen followed by one-step annealing at 900℃with low thermal budget. In this process, high concentration of nitrogen and vacancy could be injected which could strongly enhance oxygen precipitation in the following annealing. At the same time, in the subsurface of the silicon wafer, the nitrogen and vacancy concentration is much lower, hence, no oxygen precipitate is formed in the zone, which is so-called denuded zone. The new IG process is confirmed to be effective by Cu contamination test.(3) There are more grown-in oxygen precipitates in NCZ than in CZ, which work as nuclei to promote OSF formation during thermal oxidation. High temperature RTP in argon make the grown-in oxygen precipitates dissolve to suppress OSF formation. But RTP in nitrogen, high concentration of nitrogen would be injected into silicon, and the injected nitrogen would enhance oxygen precipitation at the early stage of thermal oxidation process again.