Research On Surface Acoustic Wave MEMS Device

Surface Acoustic Wave (SAW) is an elasticity, which was discovered by the British physicist Rayleigh in the study of seismic wave. Along with SAW technology developing, due to its unique advantages such as low volume, versatility, stability, reliability and mass production, the SAW device becomes one of the three families of solid microelectronic devices and is widely used in many kinds of areas of military and civil such as aerospace, radar, electronic.The paper introduces the theory, design, the fabricate technology of SAW device and researches the optimization and testing of the device. The contents of this thesis include the following:①The SAW theory was introduced, the SAW devices with different frequencies were designed and the mask was drew using L-Edit software, then the influence of the prebake time, the exposure time, and the development time on the lithography process of the high and low frequency SAW device is studied, and the metal electrode is made.②The SAW MEMS gyroscope fabricate technology was studied on the above basis, and the results clearly show that a good resist pattern can be got when 128°YX LiNbO3 is used as substrate and the parameters is the prebake temperature of 105℃for 60s, the exposure time of 12s, and the development time of 65s.The consistency of the metal matrix measurement was tested by polarizing microscope, step profile measuring instrument and non-contact surface profiler systems. The test results show that the lattice consistency is good in the 5% error range, and the test results are consistent using different test methods.③The test method of the SAW device was explored and the test platform was built using the network analyzer to test the center frequency and interpolation loss. The test results show that the testing signal of SAW device near the center frequency is strongest, and the operating frequency and the design frequency is consistency, in the 10% error range.④The optimization of the SAW devices was explored. The Diamond-like Carbon (DLC) was deposited on the piezoelectric substrate by pulse arc ion plating to improve properties of SAW devices. The experimental results show that the film quality is best when the experimental parameters are as follows:the pressure of 2×10-3Pa～4×10-3Pa, the frequency of 3Hz, the striking voltage of 400V, the main circuit voltage of 200V, the temperature of 200℃and the deposition time of 5min. Moreover, the operating frequency of the device with different DLC is increased by more than 13%-32%.