一种新型压力传感器结构制备工艺

A Novel Fabrication Process for the Structure of Pressure Sensors

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 double mask MEMS self-alignment etching process was proposed. The fine fabrication of the high aspect ratio for the micro silicon pressure sensor structure in the deep cavity was achieved by this technology. The composited mask was formed using the membrane material such as SiO2 or Si3 N4 and photoresist deposited on the substrate with two consecutive in-plane lithographic process. Each patterned mask can be used for substrate etching in different function regions. The certain mask layer can be removed after it is etched. Therefore the complicated silicon structure in the deep cavity was fabricated precisely with the combination of the multi-layer masks. The process solves the fabrication issue of the complicated silicon structure in the deep cavity, avoiding the difficulty of photoresist coating and lithography in the deep cavity. The alignment and lithography processes can be performed in the same plane, greatly improving the process accuracy, and overcoming the technology bottleneck of the pressure sensor with the multi-layer complicated structure processed in the deep cavity with the island. The absolute pressure sensor with the island-membrane structure designed and processed based on the above process is of high sensitivity and linearity at 100 kPa. The test results of the samples show that the sensitivity reaches 0. 514 mV/（V · kPa）, the linearity reaches 0.12%, and the repeatability is 0.04% for a full scale output （FSO）.