Doll Joseph C, Petzold Bryan C, Ninan Biju, Mullapudi Ravi, Pruitt Beth L
Department of Mechanical Engineering, Stanford University, Stanford, CA, USA.
J Micromech Microeng. 2010;20(2):25008. doi: 10.1088/0960-1317/20/2/025008.
Piezoelectric materials are widely used for microscale sensors and actuators but can pose material compatibility challenges. This paper reports a post-CMOS compatible fabrication process for piezoelectric sensors and actuators on silicon using only standard CMOS metals. The piezoelectric properties of aluminum nitride (AlN) deposited on titanium (Ti) by reactive sputtering are characterized and microcantilever actuators are demonstrated. The film texture of the polycrystalline Ti and AlN films is improved by removing the native oxide from the silicon substrate in situ and sequentially depositing the films under vacuum to provide a uniform growth surface. The piezoelectric properties for several AlN film thicknesses are measured using laser doppler vibrometry on unpatterned wafers and released cantilever beams. The film structure and properties are shown to vary with thickness, with values of d(33f), d(31) and d(33) of up to 2.9, -1.9 and 6.5 pm V(-1), respectively. These values are comparable with AlN deposited on a Pt metal electrode, but with the benefit of a fabrication process that uses only standard CMOS metals.
压电材料广泛应用于微型传感器和致动器，但可能带来材料兼容性挑战。本文报道了一种仅使用标准CMOS金属在硅上制造与CMOS后兼容的压电传感器和致动器的工艺。对通过反应溅射沉积在钛（Ti）上的氮化铝（AlN）的压电特性进行了表征，并展示了微悬臂梁致动器。通过原位去除硅衬底上的原生氧化物并在真空下依次沉积薄膜以提供均匀的生长表面，改善了多晶Ti和AlN薄膜的膜织构。使用激光多普勒振动测量法对未图案化的晶圆和释放的悬臂梁测量了几种AlN薄膜厚度的压电特性。结果表明，薄膜结构和性能随厚度而变化，d(33f)、d(31)和d(33)的值分别高达2.9、-1.9和6.5 pm V(-1)。这些值与沉积在Pt金属电极上的AlN相当，但具有仅使用标准CMOS金属的制造工艺的优势。
