大面积悬空浓硼硅薄膜ICP刻蚀工艺研究

Research on ICP etching technique of large scale free-handing P+ diaphragm

介绍了基于浓硼扩散自停止腐蚀技术的大面积悬空浓硼硅薄膜的制备工艺。研究感应耦合等离子体(ICP)刻蚀的射频功率组合、反应室气压、SF6气体流量对浓硼硅薄膜刻蚀速率的影响。针对ICP刻蚀时抽真空引起的大面积超薄膜的破裂和刻蚀引起的掩模板与薄膜粘连问题,提出用硅片做掩模的解决方案;针对超薄膜的过刻蚀问题,提出分二次刻蚀的方法来控制刻蚀时间、降低刻蚀温度、把握刻蚀终点。实验表明,通过ICP刻蚀,能将自由悬空硅薄膜加工成各种可动敏感的悬臂梁结构。

The preparation method of large scale free P ＋ diaphragm based on the boron doped and anisotropic wet etching techniques is introduced. The impact of the RF power configuration,pressure and SF6 flow rate on etching rate during ICP etching is also explored. It is indicated that silicon can be used as mask to solve the problems of large scale film break and the adhesion between mask and film which are caused by vacuum during ICP etching. In order to avoid over etching,twice etching technique can be employed to control etching time and ending point. Results of the experiment show that through etching,free P ＋ diaphragm can be fabricated into sensitive free beam which can be widely used in MEMS.