深反应离子刻蚀(DRIE)工艺在目前的硅微机械高深宽比结构加工中应用十分广泛。在SOI硅片DRIE刻蚀过程中,存在着一些被认为对刻蚀速率和结构轮廓不利的效应,如横向刻蚀(Notching)效应。通过在结构旁布置牺牲结构-硅岛,利用Notching效应加工出以悬空硅作为敏感单元的风速仪,其响应时间常数和电阻温度系数TCR(Temperature Coefficient of Resistant)分别为1.08μs和4 738×10-6/℃。正如所描述的,对于特定的微机械应用,Notching效应可以转变为一种加工优势,提高了微加工过程中的变化性。
Deep reactive ion etching is widely used in modern silicon micro-mechanical manufacture with high aspect ratio of etched features.During the DRIE of SOI wafer,an adverse reaction to etching rate and profile shape named"Notching effect"occurred.We take advantage of the"Notching effect"to fabricate an anemometer with suspended silicon sensing element.In our design,by some simple design rules,sacrificial silicon islands are placed near to the sensitive structures to release it by"Notching effect".Typical time constant measured for the sensor was 1.08 μs and the Temperature Coefficient of Resistant(TCR)value of the sensing element was measured to be 4 738×10-6/℃.For certain micromechanical applications,as described in this paper,"Notching effect"can be turned into an advantage to improve the variability of the fabrication process.