Wafer-Scale Flexible Surface Acoustic Wave Devices Based on an AlN/Si Structure

Wafer-scale flexible surface acoustic wave (SAW) devices based on AlN/silicon structure are demonstrated. The final fabricated devices with a 50μm-thickness silicon wafer exhibit good flexibility with a bending curvature radius of 8 mm. Measurements under free and bending conditions are carried out, showing that the central frequency shifts little as the curvature changes. SAW devices with central frequency about 191.9 MHz and Q-factor up to 600 are obtained. The flexible technology proposed is directly applied to the wafer silicon substrate in the last step, providing the potential of high performance flexible wafer-scale devices by direct integration with mature CMOS and MEMS technology.