基于IDT/ZnO/AlN/Diamond结构的混合SAW/BAW压力敏感元件特性研究

Characteristics of Hybrid SAW/BAW Pressure Sensing Element Based on IDT/ZnO/AlN/Diamond Structure

利用有限元方法分析了基于IDT/ZnO/AlN/Diamond不同结构混合SAW/BAW器件的声学特性,包括层状薄膜结构、ZnO薄膜刻蚀结构和填充结构。结果表明,当h_(ZnO)/λ=0.3、h_(AlN)/λ=0.5,且ZnO被完全刻蚀(d/h_(ZnO)=1)时,刻蚀结构混合SAW/BAW(准西沙瓦波)的机电耦合系数(K^(2))取得最大值6.54%,比层状结构(d/h_(ZnO)=0)提升了近一倍。刻蚀结构中,SiO_(2)和Diamond填充物的引入不仅提高了准西沙瓦波的K_(2),而且改善了其压力传感特性。当d/h_(ZnO)=1时,SiO_(2)和Diamond填充结构准西沙瓦波的压力频移分别为81.2 kHz/MPa和207.4 kHz/MPa,比刻蚀结构分别提高了58.7%和300%;同时,Diamond填充物的引入使准西沙瓦波的频率压力系数(PCF)达到最大值297×10^(-6)/MPa,比d/h_(ZnO)=0时提高了约30%。由此可知,通过引入不同的填充物可以开发不同的功能传感器,在压力、温度和气敏等传感领域将具有极大的应用前景。

The acoustic characteristics of hybrid SAW/BAW devices based on IDT/ZnO/AlN/Diamond with layered,etched,and filled structures are investigated using finite element methods.The results indicate that when h_(ZnO)/λ=0.3,h_(AlN)/λ=0.5,and the ZnO piezoelectric film is completely etched(d/hZnO=1),a maximum K^(2)of 6.54%is obtained for the hybrid SAW/BAW(named quasi-Sezawa wave)excited in etched structure,which is nearly two times that of the layered SAW structure(d/h_(ZnO)=0).The K^(2)and pressure sensing properties of the quasi-Sezawa devices are further improved by introducing SiO_(2)and Diamond fillings.As d/h_(ZnO)=1,the pressure frequency shifts of the quasi-Sezawa device with SiO_(2)and Diamond fillings are 81.2 kHz/MPa and 207.4 kHz/MPa,respectively,which are 58.7%and 300%higher than those of the etched structure.Meanwhile,the frequency pressure coefficient(PCF)of the quasi-Sezawa device with Diamond fillings is 297×10^(-6)/MPa,which is approximately 30%higher than that of the layered SAW structure.It can be concluded that different function sensors based on the hybrid SAW/BAW can be developed by introducing different fillings.This can have important application prospects in the fields of pressure,temperature and gas sensing sensors.