【作者】 张建强；

【导师】 刘彩池； 周旗钢；

【作者基本信息】 河北工业大学 ， 材料物理与化学， 2005， 硕士

【摘要】 本文分别利用Ar,N2,N2/O2(9%),N2/O2(14%)和O2作为退火气氛,研究了高温快速热处理对大直径直拉硅片中空洞型微缺陷FPDs的退火行为。研究发现,不同的退火气氛对硅片中空洞型微缺陷密度有不同的影响,其中,O2气氛下退火后硅片中FPDs密度最低,Ar气氛居中,N2气氛下退火后硅片中FPDs密度最高,当硅片在N2/O2混合气氛中退火后,随着O2含量的增加,硅片中FPDs密度减少。各种气氛下快速热处理均可降低硅片近表面区域20μm内空洞型微缺陷的密度。硅片中空洞型微缺陷的消除同时受到间隙氧浓度和点缺陷密度的影响。通过研究掺杂杂质对空洞型微缺陷FPDs及COPs密度的影响,发现掺入较大杂质原子的硅片,空洞型微缺陷密度相对较高,掺入较小杂质原子的硅片,空洞型微缺陷的密度相对较低。不同气氛下高温快速热处理后,硅片中FPDs的密度均有很大减少,Ar气氛下退火后硅片中FPDs密度低于N2气氛。轻掺B硅片在O2气氛退火后FPDs密度下降最多,而重掺Sb硅片在O2气氛退火后FPDs密度下降最少。硅中空洞型微缺陷(Void defect)和金属杂质的存在对硅材料的性能和器件的成品率都有重要影响。本文研究了不同气氛下快速预处理后,硅片中的FPDs密度和随后热处理形成的魔幻清洁区(MDZ)之间的关系,寻求能够获得低密度空洞型微缺陷和形成高质量清洁区的退火工艺。研究发现,Ar气氛或N2/O2(9%)混合气氛下RTA预处理后FPDs密度较低,随后热处理形成的清洁区较宽。并且,N2/O2混合气氛下退火可以通过调节N2/O2混合气氛中两种气氛的比例来控制空洞型微缺陷和氧沉淀诱生缺陷的密度。更多还原

【Abstract】 The influence of rapid thermal annealing （RTA） on flow pattern defects （FPDs） in Czochralski silicon wafers was investigated in this paper. Ar, N₂, N₂/O₂（9%）, N2/O₂（14%） and O₂ were used as the atmosphere of RTA, respectively. The density of FPDs depends greatly on the annealing atmosphere. The density of FPDs was the highest after annealing in N₂, and then was that in Ar. It was the lowest after annealing in O₂. In the case of N₂/O₂ mixed atmosphere, the FPDs density decreased with the increase of O₂ in the N₂/O₂ mixed atmosphere. In addition, the densities of FPDs after RTA decreased obviously on the surface and in the region of 20μm depth from the surface as well. The mechanism of the effect of annealing atmosphere on the void disappearance was discussed. The annihilation of voids was controlled by both concentration of interstitial oxygen and density of point defects.The impurities that were doped in silicon influence the density of void defects greatly. Big doping impurities increase void defects density, but small doping impurities reduce them. After RTA in Ar atmosphere at high temperature, the FPDs density decreased more in Sb-doped wafer than that in lightly B-doped wafer. In addition, the FPDs density in lightly B-doped wafer after RTA was lower in O₂ than that in Ar, but the opposite result was got in the heavily Sb-doped wafer.The relationship of FPDs and magic denuded zone （MDZ） in CZ silicon wafers was discussed after pre-RTA in different atmosphere. After pre-RTA at high temperature, the wafers were annealed at 800℃（4 hours）+ 1000℃（16 hours） to form MDZ. After annealing in Ar or N2/O₂（9%） mixed atmosphere, low FPDs density, high oxygen precipitation density and wide denuded zone occurred in wafer. In the case of N₂/O₂ mixed atmosphere, with the increase of O₂ in N₂/O₂ mixed atmosphere, the FPDs density and the oxygen precipitation density decreased. So the FPDs density and oxygen precipitation density can be controlled through adjusting the proportion of N₂ and O₂ in N₂/O₂ mixed atmosphere.更多还原