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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。
The initial thermal oxidation of single-side polished wafers was carried out by rapid thermal treatment. An ultra-thin layer of silicon oxide was prepared on the surface of crystalline silicon at 800 ℃ for 15, 30 and 60 min. Angular-resolved X-ray photoelectron spectroscopy (AR-XPS) techniques were used to analyze the thickness and chemical composition of the three initial layers of silicon oxide. The results show that the main components of these silicon oxide layers are SiO 2, and the content of Si 2 O 3, SiO 2 and Si 2 O in the transition region is less than 5%. By controlling the oxygen content, the oxide thickness is only time dependent. The thickness of the main phase SiO 2 changed with time to (4.1 ± 0.4) nm, (6.2 ± 0.6) nm and (9.6 ± 0.5) nm, respectively. According to the change of grazing angle of the Si 2p peak of SiO 2 and substrate Si, it is inferred that the fixed positive charges in the SiO 2 layers with thicknesses of 4.1 and 6.2 nm lead to the upward bending of the energy band of the n-type Si substrate. However, The fixed positive charge distribution in the SiO 2 layer decreases gradually away from the interface, indicating that the fixed positive charge mainly distributes near the interface.