碳化硅ICP刻蚀的掩膜材料

A Mask Material for SiC ICP Etching

SiC材料由于具有非常强的化学稳定性与机械硬度,不能用酸或碱性溶液对其进行腐蚀,在MEMS制备工艺中,通常采用干法刻蚀来制备SiC结构。针对干法刻蚀中遇到的问题,比较了光刻胶、Al和Ni等多种掩膜材料对SiC刻蚀的影响以及SiC与掩膜材料的选择比。实验证明,光刻胶作为掩膜,与SiC的选择比约为1.67,并且得到的台阶垂直度较差。Al与SiC的选择比约为7,但是致密性差,并且有微掩膜效应。金属Ni与SiC的选择比约为20,并且得到的台阶比较垂直且刻蚀形貌良好。最后,使用Ni作为掩膜材料对SiC压阻式加速度传感器的背腔和压敏电阻进行了电感耦合等离子体(ICP)刻蚀。

Due to very strong chemical stability and mechanical hardness,SiC materials can’t be etched by acid or alkaline solution.In the MEMS fabrication process,the SiC structure is generally fabricated by dry etching method.The effects of the mask materials,including the photoresist,Al and Ni on the SiC etching and the selectivity of the SiC and mask materials were compared to solve the problems in the dry etching process.The experiment results show that with the photoresist as the mask,the selectivity between the photoresist and SiC is about 1.67,and the verticality of the step is low.The selectivity of Al and SiC is about 7,but the density is poor,and the micro mask effect exists.The selectivity of Ni and SiC is about 20,and the vertical step and good etching morphology are obtained.Finally,using Ni as the mask material,the back cavity and piezoresistor of the SiC piezoresistive accelerometer were etched by inductively coupled plasma（ICP）etching.