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提出一种使用MEMS双层掩膜完成自对准刻蚀的工艺方法,藉此实现了在深腔结构内部对高深宽比硅压力传感器结构的精细加工。该工艺通过两次连续的平面内光刻工艺,使制作在衬底上的薄膜材料如氧化硅(SiO2)或氮化硅(Si3N4)及光刻胶等形成复合图形,每层图形化后的掩膜可以进行不同功能区的衬底刻蚀,刻蚀完毕后再去除对应的掩膜。通过多层掩膜组合使用完成深腔内复杂结构的高精度加工。这种工艺方法解决了在深腔内部进行涂胶和光刻的技术难题,对准和光刻工艺都在同一平面内完成,提高了加工精度,解决了深腔内部带有岛结构的多层复杂结构压力传感器加工的技术瓶颈。在此工艺基础上设计加工的岛膜结构100 kPa绝对压力传感器芯片具有线性度好、灵敏度高的特点,样机经测试满量程内灵敏度达到了0.514 mV/(V·kPa),线性度达到0.12%,重复性达到0.04%。
A method of using MEMS double-layer mask to accomplish self-aligned etching is proposed to realize the fine processing of the high aspect ratio silicon pressure sensor structure inside the deep cavity structure. In the process, two continuous in-plane photolithography processes are used to form a composite pattern of a thin film material such as silicon oxide (SiO 2) or silicon nitride (Si 3 N 4) and photoresist formed on the substrate. Each patterned layer The mask can be etched in different functional areas of the substrate, and then removed after etching the corresponding mask. Through the use of multi-layer mask to complete the deep cavity complex structure of high-precision machining. This process method solves the technical problem of glueing and photolithography in the deep cavity. The alignment and the lithography process are all performed in the same plane, thereby improving the processing precision and solving the problem of multiple layers with island structure in the deep cavity Technical bottleneck of complex structure pressure sensor processing. Based on this technology, the 100 kPa absolute pressure sensor chip with island membrane structure designed and processed has the characteristics of good linearity and high sensitivity. The sensitivity of the prototype reached 0.514 mV / (V · kPa) at full scale and the linearity reached 0.12% , Repeatability reached 0.04%.