基于ITO掩膜的键合片深硅刻蚀

Deep Silicon Etching of Bonded Wafer Based on ITO Mask

提出了用氧化铟锡(ITO)作为掩膜对硅与玻璃的键合片进行深硅刻蚀的工艺。ITO薄膜采用直流溅射工艺常温生长,避免了传统等离子体化学气相沉积(PECVD)方式生长氧化硅掩膜高温对器件制备造成的影响。对不同的ITO薄膜图形化方式进行了研究,结果表明垂直或正锥形台阶的光刻胶剥离工艺制备的ITO薄膜边缘光滑,尺寸误差小,是实现ITO薄膜图形化的理想方式。进一步研究了基于ITO掩膜的键合片深硅刻蚀能力,在硅刻蚀深度达到150μm时,掩膜只消耗了5.66 nm,刻蚀选择比高达26500∶1,没有发现微掩膜效应。因此利用ITO掩膜实现键合片的深硅刻蚀,掩膜的生长和图形化都在常温下进行,特别适合基于硅玻璃(SOG)键合刻蚀工艺的MEMS器件制备。

The deep silicon etching process of the bonding wafer of silicon and glass was proposed using indium tin oxide(ITO)as a mask.The ITO film was grown at room temperature by a DC sputtering process,avoiding the influence of the high temperature on the device preparation with the traditional plasma enhanced chemical vapor deposition(PECVD)method for the growth of the silicon oxide mask.Different ITO film patterning methods were investigated.The results show that the ITO film prepared by the photoresist lift-off process with vertical or positive tapered steps has smooth edges and small dimensional errors,thus the photoresist lift-off process is an ideal way to achieve ITO film patterning.Furthermore,the deep silicon etching ability of the bonding wafer based on the ITO mask was investigated.When the silicon etching depth reaches 150μm,the mask consumes only 5.66 nm,the etching selectivity ratio is as high as26500∶1,and no micro mask is found.Therefore,for deep silicon etching of bonding wafer realized with the ITO mask,the growth and patterning of the ITO mask are performed at room temperature,which is particularly suitable for the preparation of micro-electromechanical system(MEMS)devices based on the silicon on glass(SOG)process.