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介绍了一种博世(Bosch)工艺深槽刻蚀后的侧壁平坦化技术。优化深槽刻蚀工艺参数使侧壁扇贝褶皱的尺寸降低至约52 nm,然后在1 100℃炉管中热氧化生长100 nm牺牲氧化层,再用HF酸漂洗工艺去除牺牲氧化层得到完全光滑的侧壁形貌。研究表明,扇贝褶皱的底部沿<100>晶向氧化,而顶部沿<110>晶向氧化的矢量叠加方向。当热氧生长厚度较薄时,氧化行为倾向于线性氧化,由于线性氧化的速率常数强烈依赖晶向取向,因此氧化一定时间后,顶部的氧化深度与底部的氧化深度达到一致。基于上述氧化机制,Si/Si O2界面变得平滑陡直。
A technique of sidewall planarization after deep trench etching of the Bosch process is introduced. Optimized deep trench etching process parameters to reduce the size of the sidewall scallop fold to about 52 nm, and then 100% sacrificial oxide by thermal oxidation in a furnace at 1,100 ° C, then completely removed by HF acid rinsing The sidewall morphology. The results show that the bottom of scallop folds is oxidized along the <100> crystal orientation and the top is along the <110> crystal orientation. When the thickness of hot oxygen growth is thin, the oxidation behavior tends to linear oxidation. Since the rate constant of linear oxidation strongly depends on the crystal orientation, the oxidation depth at the top and the oxidation depth at the bottom are the same after oxidation for a certain period of time. Based on the above oxidation mechanism, the Si / Si O2 interface becomes smooth and steep.