【作者】 林磊；

【导师】 阙端麟； 杨德仁；

【作者基本信息】 浙江大学 ， 材料物理与化学， 2004， 硕士

【摘要】 近年来，快速热处理(Rapid thermal processing，RTP)已经用于控制直拉硅单晶的生产和研究。世界著名的硅材料供应商—美国的MEMC提出了一种基于RTP的所谓的“魔幻洁净区”(Magic Denuded Zone，MDZ)技术，其基本思想就是利用RTP在硅片中形成浓度从表面到体内逐步升高的空位分布，利用空位来控制后续热处理中氧沉淀，从而在硅片体内形成高密度的氧沉淀而在近表面形成洁净区。可以认为MDZ技术是具有里程碑式的意义，在它背后还蕴涵了一个基本的科学问题，即：空位是如何影响氧沉淀的?本文就这个基本问题进行了一系列的研究，得到了一些有意义的结果。 研究了不同温度的RTP对直拉(CZ)硅片在两步(低-高)退火中氧沉淀的影响，结果表明：对于两步退火来说，RTP引入的空位参与了氧沉淀核心的形成，因而促进了随后高温热处理中的氧沉淀；特别是在实验中发现：样品经过两步退火后的氧沉淀量与RTP处理的温度呈正相关关系。 研究了经过RTP处理过的直拉硅片在低温和中温(650℃，750℃，850℃和950℃)下长时间处理的氧沉淀行为，分析表明：由RTP引入的空位能促进这些温度下氧沉淀核心的形成。 研究了经过RTP处理过的直拉硅片在高温(1050℃)下长时间处理的氧沉淀行为，结果表明：在高温下，空位没有参与氧沉淀的成核，而是显著加速了早期的氧沉淀，但是它没有增加长时间处理后的氧沉淀量。特别是，经过高温长时间热处理后，与未经RTP预处理的直拉硅片相比，经RTP预处理过的直拉硅片具有更低密度的氧沉淀，尽管它与前者具有相同的氧沉淀量。进一步的分析表明：这是由于在RTP预处理阶段，直拉硅片中的一部分原生氧沉淀被消除。 在论文的最后，还研究了快速热处理对直拉硅中氧沉淀消融的作用，发现用快速热处理在较短的时间内就可以消除直拉硅片中的部分氧沉淀，这表明热处理温度是氧沉淀消融的最主要的决定因素。更多还原

【Abstract】 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 main idea underlying the MDZ process is to enable the oxygen precipitation in CZ silicon wafer to be controlled by an RTP-created vacancy profile with the vacancy concentration increasing from the surface to bulk of wafer, thus forming a denuded zone above the region of high density bulk micro-defects (BMDs). 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.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 and, therefore, enhancing the oxygen precipitation during the subsequent high temperature anneal; the amounts of precipitated oxygen in the samples were positively in proportional to the RTP temperature.During the single-step high temperature (1050℃) anneal, the RTP-induced vacancies significantly enhance the early stage oxygen precipitation in terms of precipitation rate, but do not increase the amount of precipitated oxygen in the CZ silicon wafer subjected to prolonged anneal. It was found that after lengthy anneal at 1050℃ the silicon wafer with prior RTP treatment had relatively lower density of BMDs than the one without prior RTP treatment, the reason for which is that the prior RTP treatment had dissolved a part of grown-in oxygen precipitates that are the nuclei of oxygen precipitation occurring at 1050℃.Through investigating the effects of RTP-induced vacancies on the oxygen precipitation in CZ silicon wafers subjected to lengthy anneals at 650℃,750℃,850℃and 950℃, it is revealed that the vacancies significantly foster the nucleation of oxygen precipitation occurring at the above-mentioned temperatures.Moreover, it has been found that the RTP at high temperatures has superior capability to dissolve the oxygen precipitates existing in the CZ silicon wafer, implying that the dissolution of oxygen precipitates is primarily determined by the anneal temperature, not like the case of oxygen precipitation that is dependent on both anneal temperature and time.更多还原