Grown-in defects in nitrogen-doped Czochralski silicon

Abstract

Grown-in defects including oxygen precipitates and voids in nitrogen-doped Czochralski (NCZ) silicon have been investigated. It was found that the formation of grown-in oxygen precipitates in NCZ silicon can be divided into two stages. The large precipitates supposed to be enhanced by N2–V2–Ox complexes are generated around 1150 °C, while the small precipitates supposed to be enhanced by NmOn complexes are formed at 750 °C and below. Moreover, it was revealed that the oxygen precipitation behavior in the mixed-type NCZ silicon, which contains vacancy-type and interstitial-type defects distinguished by an OSF-ring in the oxidized wafer, is in sharp contrast to that in the mixed-type Czochralski (CZ) silicon, when subjected to one-step high temperature annealing (1050 °C/32 h) and two-step annealing (800 °C/4 h+1050 °C/16 h). On the other hand, it was found that, compared with CZ silicon, NCZ silicon has much denser crystal originated particles in smaller sizes, which were verified to have been annihilated at relatively lower temperatures. Based on the experimentally found phenomena, a tentative model that takes into account the formation of nitrogen-related complexes involving oxygen atoms and vacancies, void formation, and oxygen precipitation is presented.