低起始温度的线性升温热处理对直拉硅中氧沉淀的影响

Effect of ramping from low temperatures on oxygen precipitation in Czochralski silicon

研究了直拉硅片从不同的温度线性升温(Ramping)到750℃,然后在750℃退火64h过程中的氧沉淀行为.结果表明,Ramping对硅片中氧沉淀的形成有明显的促进作用,且起始温度越低促进作用越强.这是因为在Ramping处理中,低温(450—650℃)热处理阶段氧的扩散速率显著增强,促进了氧沉淀核心的形成,且较低的Ramping升温速率有利于氧沉淀核心的稳定和继续长大.进一步的实验结果还表明,低起始温度的Ramping处理可应用于硅片的内吸杂工艺,能促进氧沉淀的生成提高硅片的内吸杂能力,减少热预算,但不适用于魔幻洁净区(MDZ)工艺.

Czochralski （CZ） silicon wafers were firstly subjected to a variety of ramping annealing from low temperatures to 750℃, and then subjected to a prolonged anneal at 750℃ for up to 64 h. It was revealed that the prior ramping anneal from low temperature lead to strong enhancement of oxygen precipitation in the subsequent annealing, and the lower the starting temperature the stronger the enhancement. It is considered that at low temperatures （450-650℃） the diffusion of oxygen was greatly enhanced and therefore the nucleation of oxygen precipitation was facilitated. Moreover, the slow ramping rate could also increase the stability as well as facilitate the growth of the oxygen precipitate nuclei formed at low temperature. A novel internal gettering （IG） process based on ramping anneal from low temperature has been developed, which can reduce the annealing time and therefore the thermal budget. However, the ramping anneal from low temperature is not available for the application of magic denude zone （MDZ） process.