超薄SiO_2层的化合态结构和厚度

Compound States Profile and Thickness of Ultra-thin Silicon Dioxide Film

用快速热处理对单面抛光硅片进行初始热氧化,800℃下在晶硅基表面制备出15,30和60 min三个时间段的超薄氧化硅层。采用角分辨X射线光电子谱(AR-XPS)技术分别分析了3种初始氧化硅层的厚度和化学组态。结果表明,这些氧化硅层的主要成分为SiO_2,在过渡区存在的Si_2O_3、SiO和Si_2O不饱和态的含量均小于5%。通过控制氧气的含量,使氧化厚度只与时间有关。氧化硅层主相SiO_2的厚度随时间改变分别为(4.1±0.4)nm,(6.2±0.6)nm和(9.6±0.5)nm。根据SiO_2与基底Si的Si_(2p)峰的间距随掠射角度的变化,推断出厚度为4.1和6.2 nm的SiO_2层内的固定正电荷导致n型Si基体能带向上弯曲;而9.6 nm的SiO_2层内的固定正电荷分布随着远离界面逐渐减小,表明固定正电荷主要分布在界面区附近。

By rapid thermal process, the initial thermal oxidation of single-side polished silicon wafer has been accurately obtained at 800℃ by oxygen switching for 15, 30 and 60 min oxidation time to form ultra thin silicon oxide layers. The ultra thin silicon oxidation layers were analyzed. The results show that the main composition of these layers is silicon dioxide, and the thicknesses are （4.1±0.4） nm, （6.2±0.6） nm and （9.6±0.5） nm, respectively. The incomplete oxides of Si2O3, SiO and Si2O all less than 5% of total oxidation layer formed at the interface between Si and SiO2. For those silicon oxide layers with the thickness of 4.1 and 6.2 nm, the difference of the binding energy between SiO2 and Si increases with decrease of graze angles, and the kinetic energy of photoelectron is affected by the build-in potential in the surface of the n-type silicon substrate. However, for the layers with 9.6 nm thick silicon oxide, the kinetic energy of photoelectron is dominated by the positive charge in the silicon oxide.