【作者】 王剑；

【导师】 马向阳； 杨德仁； 田达晰；

【作者基本信息】 浙江大学 ， 材料工程， 2014， 硕士

【摘要】 直拉硅抛光片的表面质量和氧沉淀对集成电路成品率的影响很大。无论在硅片生产还是在集成电路制造中,硅片都要经过高温退火。因此,高温退火对硅片表面质量和氧沉淀影响的研究显得十分重要。本文研究了200mm直拉硅抛光片经高温退火后的表面状态以及氧沉淀,取得了如下主要结果：1.研究了实际生产中200mm单面抛光硅片在消除表面空洞型缺陷的1200℃退火工艺后,表面出现彩雾和白雾的问题。通过清洗炉管消除金属沾污而解决了彩雾问题；通过更换抛光方式消除了肉眼可见的白雾,但由激光颗粒计数仪检测到的表面haze (雾)较显著且分布不均匀,且这样的表面haze与表面微微粗糙度没有明确的对应关系。表面haze看起来是高温热处理的“顽疾”,可通过表面精抛加以消除。2.研究了高温预退火对直拉硅片在后续退火工艺中氧沉淀的影响。发现高温预退火能显著促进直拉硅片在后续低-高两步退火工艺或高温RTP-低-高三步退火工艺中的氧沉淀,且高温预退火时间越长,对氧沉淀的促进越显著。这种促进作用的机制在于：高温预处理可以消融原生氧沉淀,因而消除了伴生的自间隙硅原子,为后续新的氧沉淀的形核提供了有利条件。3.将高温预处理应用在基于快速热处理的直拉硅片内吸杂(MDZ)工艺时,可大幅度缩短氧沉淀长大的高温退火时间,并形成更高密度的体微缺陷,从而提高硅片的内吸杂能力。结果表明,高温预处理可以减少MDZ工艺的热预算。更多还原

【Abstract】 Surface quality and oxygen precipitation (OP) of the polished Czochralski (Cz) silicon wafers are of significance for manufacturing yield of integrated circuits (ICs). The Cz silicon wafers are generally subjected to high temperature anneal in either silicon wafering or IC fabrication processes. Therefore, it is necessary to explore the effects of high temperature anneal on the surface quality and OP of CZ silicon wafers. In this thesis, the surface status and OP in200mm polished CZ wafers received high temperature anneal have been investigated. The primary results are described as follows:1. The issues of appearing colorful and white hazes during1200℃anneal that is used for annihilation of crystal-originated-particles in200mm CZ silicon wafers have been addressed. The colorful hazes can be eliminated by cleaning the furnace tube for removal of metal contaminations. While the visible white hazes can be eliminated by appropriate polishing means, the hazes detected by laser scatterometer are significant and distribute non-uniformly across the wafers. Such surface hazes are not well correlated with the surface micro-roughness.. It seems that the appearing of surface hazes is a "persistent ailment" of high temperature anneal for CZ silicon wafers. It can be cured by a refine polishing process.2. The effects of high temperature pre-anneal on OP in Cz silicon wafers have been investigated. It is found that the high temperature pre-anneal can significantly enhanced OP in the subsequent low-high two-step anneal and the three-step anneal consisting of high temperauture RTP and low-high conventional furnace anneal. Such enhancement effect becomes stronger with increasing time of pre-anneal at high temperature. It is believed that the high temperature pre-anneal annihilates the grown-in oxygen precipitates and therefore the accompanied silicon-interstitials, which facilitates the OP nucleation in the subsequent anneal.3. It is found that the application of high temperature anneal prior to the RTP-based internal gettering (IG) process can substantially reduce the annealing time for the growth of oxygen precipitates at high temperature and, moreover, increase the bulk micro-defect density and therefore the IG capability. It is shown that the high temperature pre-anneal can be used to reduce the thermal budget of the RTP-based IG process.更多还原