反应离子深刻蚀中硅/玻璃结构footing效应的实验研究

针对反应离子深刻蚀中硅/玻璃键合结构的footing效应问题,用实验方法进行了研究.通过2～4和0.01～0.03Ω·cm两种不同电导率的硅结构过刻蚀的对比,以及对50,20和5μm三组不同间隙高度的器件结构过刻蚀的对比,揭示了单晶硅结构的电导率及器件结构和玻璃衬底间隙高度对footing效应的影响.实验结果显示电导率为2～4Ω·cm的硅结构比电导率为0.01～0.03Ω·cm的硅结构footing效应严重;硅结构和玻璃衬底的间隙为5μm的比间隙为20和50μm的footing效应严重, 对这一现象的理论分析认为,被刻蚀的硅的电导率越高, 硅结构与玻璃衬底的间隙越大,footing效应越不明显.本文中不同电导率和不同间隙高度的实验对比结果可以为硅微传感器材料类型的选取和器件的优化设计提供参考.

Experimental Study on the Footing Effect for SOG Structures Using DRIE

This paper experimentally studies the effects of the conductivity of a silicon wafer and the gap height between silicon structures and glass substrate on the footing effect for silicon on glass (SOG) structures in the deep reactive ion etching (DRIE) process. Experiments with gap heights of 5,20, and 50μm were carried out for performance comparison of the footing effect. Also,two kinds of silicon wafers with resistivity of 2～4 and 0.01～0.03Ω·cm were used for the ex- ploration. The results show that structures with resistivity of 0.01～0.03Ω · cm have better topography than those with resistivity of 2～4Ω · cm; and structures with 50μm-high gaps between silicon structures and glass substrate suffer some-what less of a footing effect than those with 20μm-high gaps, and much less than those with 5μm-high gaps. Our theoretical analysis indicates that either the higher conductivity of the silicon wafer or a larger gap height between silicon structures and glass substrate can suppress footing effects. The results can contribute to the choice of silicon type and optimum design for many microsensors.