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硅片背面沉积多晶硅是半导体生产中常用的吸杂手段,多晶硅中存在着大量的晶界,可以吸除金属杂质,它还可以影响硅片内氧沉淀的分布,增强内吸杂的作用。通过控制低压化学气相沉积(LPCVD)系统的沉积时间,在硅片背面沉积不同厚度的多晶硅薄膜,借助择优腐蚀和金相显微(OM)观察等手段研究了沉积厚度对重掺硼硅片内氧沉淀形成与分布的影响。结果表明:沉积的多晶硅薄膜越厚,硅片的形变量越大,小尺寸的氧沉淀数量增多并在表面附近聚集,大尺寸的氧沉淀则倾向于在体内和背面形成,洁净区的厚度则减小直至无洁净区建立。多晶硅薄膜通过对硅片施加应力引起硅片形变,从而影响氧沉淀硅片体内形成的位置,起到促进内吸杂的作用。最佳多晶硅沉积厚度为800 nm。
Silicon on the back of the deposition of polysilicon is commonly used in semiconductor manufacturing, means of absorbing impurities, polysilicon, there are a large number of grain boundaries, metal impurities can be sucked, it can also affect the distribution of oxygen within the silicon deposition and enhance the role of gettering. By controlling the deposition time of low pressure chemical vapor deposition (LPCVD) system, different thicknesses of polycrystalline silicon films were deposited on the backside of silicon wafers. The effects of deposition thickness on the oxygen precipitates in heavily boron doped silicon wafers were investigated by means of selective etching and OM observation. The formation and distribution of the impact. The results show that the thicker the polycrystalline silicon film is deposited, the larger deformation amount of the silicon wafer is. The smaller the size of the oxygen precipitation is, the larger the size of the oxygen precipitate is. The large size of the oxygen precipitation tends to form in the body and the back. The thickness of the clean area Reduce until no clean area is established. Polysilicon film by silicon wafer stress caused by silicon deformation, thus affecting the oxygen deposition of the formation of silicon body position, play a role in promoting the gettering. The best polysilicon deposition thickness is 800 nm.