Parylene增强型声表面波传感器及其温度响应

Parylene-enhanced SAW sensor and its temperature response

针对声表面波(SAW)传感器对品质因数、寿命和成本的要求,研制了Parylene增强型SAW传感器。根据金属剥离工艺要求,利用LOR剥离胶和AZ5214光刻胶双层胶旋涂工艺制作了梯形结构;在传统光学光刻条件下制作了2μm的超细叉指电极。传感器制作过程利用了MEMS工艺,不仅实现了传感器的微型化,还可以批量化生产,得到的以石英为基底的传感器谐振频率达到249.077 953 MHz。最后在传感器的表面镀制Parylene聚合物薄膜以提高基底温度灵敏度。实验对比了未增强型(未镀Parylene)和增强型SAW传感器(镀Parylene)的温度灵敏度。结果显示:未增强型SAW传感器温度灵敏度为2.048kHz/℃,Parylene增强型SAW传感器温度灵敏度为2.855kHz/℃,比前者提高了0.807kHz/℃,且镀Parylene之后谐振频率变化量与温度具有较好的线性度,线性相关系数达到0.996 15。实验证明,Parlene增强型SAW传感器的性能优于未增强的SAW传感器。

According to the requirement of Surface Acoustic Wave（SAW）sensors for quality factors,long life and low costs,a Parylene enhanced SAW sensor was developed.In consideration of metal stripping process,the LOR stripping rubber and AZ5214 double-layer spin-coating process were used to produce a trapezoidal structure,and the traditional optical lithography was used to fabricate a 2μm superfine fork finger electrode.By utilizing MEMS technology,the sensor implements the miniaturization,but also the quantified production.The obtained quartz-based sensor shows its resonant fre-quency to be 249.077 953 MHz.Finally,a Parylene polymer film was coated on the surface of the sensor to increase the temperature sensitivity of the substrate.The temperature sensitivities of unenhanced SAW sensor（uncoated parylene）and enhanced SAW sensor（coated parylene）were compared experimentally.The results indicate that the temperature sensitivity of the former is 2.048 kHz/℃and that of the latter is 2.855 kHz/℃,which is higher 0.80 kHz/℃than that of the former.Moreover,the resonant frequency offset and the temperature of the Parylene-enhanced SAW sensor show an excellent linearity,and the linear correlation coefficient reaches to 0.99615.These experiments demonstrate that performance of Parylene-enhanced SAW sensors is superior to that of the unenhanced SAW sensors.