Thermal Oxidation of Phosphorus‐Doped Polycrystalline Silicon in Wet Oxygen
Thermal Oxidation of Phosphorus‐Doped Polycrystalline Silicon in Wet Oxygen
复制标题
湿氧中磷掺杂多晶硅的热氧化
DOI：
10.1149/1.2131586
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发表时间：
1978
影响因子：
3.9
通讯作者：
H. Sunami
中科院分区：
文献类型：
--
作者：
H. Sunami
根据线性-抛物线速率定律，研究了重掺磷多晶硅薄膜和单晶硅衬底在700~ 176℃的湿氧环境下的氧化特性。通过扩散驱动或离子注入，研究了未掺杂或均匀掺杂1.1 X 1019-2.2 X 102i cm-~磷的多晶硅，并与轻掺杂或重掺杂的硅衬底（100），（110）和（111）进行了比较。磷浓度大于1•1020 cm-8会导致氧化速率显著增加。然而，在1 × 1021 cm-3以上，氧化率趋于饱和。在氧化的初始阶段观察到非常迅速的氧化。这种初始氧化物不符合线性-抛物线速率定律。当磷浓度约为6 × 1020 cm-g时，掺磷多晶硅的电阻率在5 × 10-4 cm处最小。通过氧化使多晶硅厚度减小后，其初始电阻率几乎保持不变。此外，沿晶界没有观察到氧化增强的证据。近二十年来，人们对硅的热氧化动力学进行了广泛的研究。一个结果是引入了线性抛物率定律(1)，它成功地描述了实验结果。从线性抛物线模型推导的速率常数的活化能在文献中发现在0.4和2.3 eV(2)之间变化。活化能的差异被有效地归因于硅的热氧化受到环境中钠污染(2)和/或水痕迹的高度影响（3,4）。此外，硅掺杂剂浓度大于1 X 1020 cm-~（5,6）也会影响硅的热氧化。在干燥氧化中，掺杂剂浓度对速率常数的依赖性已被报道过(7)。虽然浓度依赖性氧化（CDO）在湿氧中最为明显(5)，但CDO的动力学尚未得到彻底的分析。
Oxidation characteristics of heavily phosphorus-doped polycrystalline silicon films and single crystal silicon substrates are investigated in a wet oxygen ambient over the temperature range 700~ 176 based on the linear-parabolic rate law. Polysilicon, undoped or uniformly doped with phosphorus of 1.1 X 1019-2.2 X 102i cm-~ by diffusion drive-in or ion implantation, is studied in comparison with lightly doped or heavily doped (100),(110), and (111) faces of silicon substrates. Phosphorus concentrations greater than 1• 102o cm-8 cause a significant increase in oxidation rates. Above 1 X 1021 cm-3, however, oxidation rates tend to become saturated. A very rapid oxidation in the initial stage of oxidation is observed. This initial oxide does not fit the linear-parabolic rate law. The resistivity of the phosphorus-doped polysilicon is minimized at 5 X 10-4~-cm for a phosphorus concentration of around 6 X 1020 cm-g. The initial resistivity remains almost constant after reduction of the polysilicon thickness by oxidation. In addition, no evidence of enhanced oxidation along the grain boundaries is observed.The thermal oxidation kinetics of silicon have been extensively investigated over the past twenty years. One result was the introduction of the linearparabolic rate law (1) which successfully characterizes experimental results. The activation energies for the rate constants derived from the linear-parabolic model are found in the literature to vary between 0.4 and 2.3 eV (2). Discrepancies in activation energies have been validly attributed to the fact that thermal oxidation of silicon is highly influenced by sodium contamination (2) and/or water traces in the ambient (3, 4). In addition, thermal oxidation of silicon is also influenced by silicon dopant concentrations greater than 1 X 1020 cm-~(5, 6). The dopant concentration dependence of rate constants was previously reported for dry oxidation (7). Although concentration dependent oxidation (CDO) is most pronounced in wet oxygen (5), the kinetics of CDO have not been thoroughly analyzed yet.