外延用300mm重掺B Si衬底中热致微缺陷研究

Investigation of Thermally Induced Microdefects in 300 mm Heavily Boron Doped Si Substrates Used for Epitaxy

研究了重掺B对300 mm直拉Si衬底中热致微缺陷的影响。通过800℃/4～16 h+1 100℃/16 h的低-高两步退火处理发现,与普通(CZ)Si片相比,重掺B(HBCZ)Si片体内生成了高密度的热致微缺陷——体微缺陷(BMDs);B浓度的不同对BMDs的形态也有重要影响,重掺BSi片中出现杆状层错,随着B浓度的增加,层错密度增加,尺寸减小。研究表明,重掺B对BMDs的促进作用主要归功于B原子促进了氧沉淀的异质形核并由于原子半径效应使得这些核心较容易长大,而晶体中初始氧含量不是重掺B促进氧沉淀的主要因素。

The effect of heavily boron doping on thermally induced micro defects in 300 mm Czochralski （CZ） Si substrates was investigated. After low-high temperature （800℃/4 ～ 16 h ＋ 1 100 ℃/16 h） two-step annealing, it is found that the density of thermally induced microdefects as well as BMDs （bulk micro defects） in heavily boron doped wafers is much higher than that in conventional wafers. In addition, the morphology of BMDs is also affected by boron concentration, and rod-shaped stacking faults are found in HBCZ （heavily boron doped Czochralski） samples. The density of stacking faults increases and the size of stacking faults decreases with the boron concentration increasing. It is shown that the BMD is enhanced in HBCZ Si mainly due to the heterogeneous nucleation of oxygen precipitation facilitated by boron atoms, and the precipitate nuclei will grow more easily because of the covalent radii effect of boron, however, the initial oxygen content is not the main factor for the enhancement of oxygen precipitation in HBCZ Si.