Oxygen diffusion and precipitation in Czochralski silicon
Oxygen diffusion and precipitation in Czochralski silicon
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DOI：
10.1088/0953-8984/12/25/201
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发表时间：
2000-06
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影响因子：
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通讯作者：
R. Newman
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文献类型：
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作者：
R. Newman
本文的目的是回顾我们对用于制造集成电路(IC)的直拉硅中氧杂质的性质的了解。这些原子以~1018厘米-3的浓度存在，占据了原生硅中的键中心位置(OI)，相邻位置之间的跳跃速率定义了温度范围为第1325-330°C的正常扩散。高温下的退火会导致形成非晶态的二氧化硅沉淀，作为快速扩散的金属污染物的陷阱，例如铁和铜，可能会无意中引入低至1011厘米-3的水平。如果没有这种‘吸气’，制造的IC可能会严重退化。为了适应氧沉淀过程中局部体积的增加，存在平行生成的自间隙，它们扩散开并形成晶格缺陷。高温(T>；700°C)退火热处理现已广为人知。低温过程的细节仍然是一个有争议的问题：对氧扩散进出硅表面和OI原子聚集的测量表明，增强的扩散被不同地归因于OI原子与晶格空位、自间隙、金属元素、碳、氢杂质等的相互作用。有强有力的证据表明，在T<；500℃时，氧-氢相互作用和快速扩散的O2二聚体的形成。这些观察结果在理解小氧团簇的生长和结构方面取得了重大进展，这些小氧团簇被识别为所谓的热施主缺陷和浅层热施主缺陷。有必要改进这一理解，因为随着未来器件特征的尺寸降低到亚微米范围的下端以下，器件处理的温度将继续下降，目前接近0.18微米。
The objective of this article is to review our understanding of the properties of oxygen impurities in Czochralski silicon that is used to manufacture integrated circuits (ICs). These atoms, present at a concentration of ~1018 cm-3, occupy bond-centred sites (Oi) in as-grown Si and the jump rate between adjacent sites defines `normal' diffusion for the temperature range 1325 - 330 °C. Anneals at high temperatures lead to the formation of amorphous SiO2 precipitates that act as traps for fast diffusing metallic contaminants, such as Fe and Cu, that may be inadvertently introduced at levels as low as 1011 cm-3. Without this `gettering', there may be severe degradation of fabricated ICs. To accommodate the local volume increase during oxygen precipitation, there is parallel generation of self-interstitials that diffuse away and form lattice defects. High temperature (T > 700 °C) anneals are now well understood. Details of lower temperature processes are still a matter of debate: measurements of oxygen diffusion into or out of the Si surface and Oi atom aggregation have implied enhanced diffusion that has variously been attributed to interactions of Oi atoms with lattice vacancies, self-interstitials, metallic elements, carbon, hydrogen impurities etc. There is strong evidence for oxygen-hydrogen interactions at T < 500 °C and the formation of fast diffusing O2 dimers. These observations have led to significant advances in understanding the growth and structures of small oxygen clusters, identified with the so-called thermal donor and shallow thermal donor defects. There is a need to improve this understanding because the temperatures of device processing will continue to decrease as the size of future device features decreases below the lower end of the sub-micron range, currently close to 0.18 µm.