| In recent years, rapid thermal processing (RTP) has been employed in the manufacturing and research of Czochralski (CZ) silicon wafer. MEMC Electronic Materials, Inc., a worldwide famous silicon wafer manufacturer, has developed a so-called 'Magic Denuded Zone (MDZ)' process based on RTP. The MDZ process initiates a fundamental problem that how the vacancy affects the oxygen precipitation in CZ silicon, which has been addressed in this thesis. Thorough a series of investigation, the following conclusions have been derived.1) As for the standard two-step anneal of 800℃/4h +1000℃/16h used in the MDZ process, the RTP-introduced vacancies are involved in the formation of oxygen precipitate nuclei during the low temperature anneal, thus enhancing the oxygen precipitation during the subsequent high temperature anneal. The amount of precipitated oxygen in the samples was positively in proportional to the RTP temperature.2) Through investigating the effects of RTP(1100℃ ~ 1280℃) on the oxygen precipitation in heavily boron-doped CZ silicon wafers subjected to lengthy anneals at 900~1150℃, we found that a) in samples with prior RTP at above 1200℃, there were almost no oxygen precipitates formed when annealed at 1150℃, while in samples with prior RTP at 1100℃, certain amount of oxygen precipitates were formed, but it is still not comparable to that in samples without prior RTP. This phenomenon indicated that the size of most of the as-grown precipitates were larger than the critical sizes of oxygen precipitates at 1150℃;and that high temperature anneal would dissolve most of the as-grown precipitates remarkably. When the RTP temperature was above 1200℃, the as-grown precipitates were dissolved completely. Moreover, it is reasonable to conclude that B-0 complexus still can weren't formed at 1150℃ in spite of a very high vacancy concentration in heavily boron-doped silicon, b) During the one-step anneal at 800 — 1050℃, a high density of oxygen precipitates were formed in samples with prior RTP at 1280℃, while a very low density of oxygen precipitates were formed in samples with priorRTP at 1200°C, indicating that vacancies promoted the formation of oxygen precipitates nuclei(B-0 complexus), as the vacancies could provide space for stress relaxation during the nuclei formation period, c) During the anneal at 900~1050°C, the density of oxygen precipitates in samples with prior RTP at 1200°C was lower than that in samples with prior RTP at 1100°C. This is because that RTP 1200°C dissolved the oxygen precipitates more thoroughly, d) When annealed at 800°C, the oxygen precipitates concentration in samples with prior RTP at 1100°C and without prior RTP was lower than that in samples with prior RTP at 1200°C and 1280"C. This is because that RTP above 1200°C could eliminate the silicon self-interstitials created during the formation of oxygen precipitates more efficiently, thus eliminating the factor that impeding the oxygen precipitates formation in the subsequent one-step anneal, e) B-0 complexus acting as the heterogeneous nuclei centre in heavily boron-doped silicon were formed during 800~1050°C, and vacancies were very important for the formation of B-0 complexus.3) Moreover, it has been found that oxygen precipitation in the CZ silicon wafer with the prior 1250°C anneal with fast or slow cooling rate was significantly enhanced during the subsequent low-high two-step heat treatment. It is believed that the prior 1250°C anneal with fast cooling rate introduced a considerable amount of vacancies, thus enhancing oxygen precipitation in the subsequent anneal;while, that with slow cooling rate substantially removed the silicon interstitials generated during the formation of grow-in oxygen precipitates, thus eliminating the retard effect on oxygen precipitation in the subsequent anneal.
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