用于MEMS非致冷红外传感器的氧化钒工艺

Fabrication of VOx for MEMS-Based Uncooled IR Sensors

基于VOx的非致冷红外传感器是当前MEMS的研究热点。VOx的制作是关键工艺,而VOx多价态共存,优化工艺以提高VO2在VOx中的比例、制备高性能的VOx薄膜为核心技术。采用直流磁控溅射法,对量产型PVD机台进行了技术改造,在溅射过程中用电压同时控制靶材溅射速率和氧气流量,少量的氩气充当靶材的保护气体。溅射完成后在350℃下退火约3h以降低噪声和残余应力。经测试,得到的氧化钒薄膜电阻温度系数(TCR)的绝对值大于2.8%/K,EDX分析得V和O的原子数比约为1∶1.8,像元均匀性优于5%,封装后样品等效噪声温差小于100mK,并给出了384×288阵列样品的红外成像效果图。结果表明:采用的方法有助于实现相关成像阵列的量产化。

Uncooled infrared（IR）sensors based on vanadium oxide（VOx）are the current hotspot in MEMS research.Fabrication of VOx is the critical technique in the preparation of uncooled IR sensors.However,most of the reported VOx is a mixture of different oxides with variable valences.The proportion of VO2 in this mixture must be improved to achieve VOx film with high performance by process optimization.The target sputtering rate and O2 flow were voltage-controlled simultaneously in a VOx sputtering process.The PVD machine was renovated to meet the demands.In addition,some argon was needed to provide protection for the target.After the deposition,VOx film annealed at 350 ℃ for about 3 h to reduce noises and residual stress.The test results show that VOx film has the absolute value of TCR more than 2.8%/K and the atomicity ratio of V/O about 1/1.8 by EDX spectroscopy.In result,the uniformity of pixels is better than 5%,and the noise equivalent temperature difference of a packaged sample is less than 100 mK.The IR photograph of 384×288 array was shown.The results indicate that the volume production of related arrays is realized by the adoptive methods.