Integrated Isolation Structure for Reducing Thermal Stresses of Resonant Pressure Microsensor

This article presents an all-silicon resonant pressure microsensor with a new isolation method to avoid the influence of thermal stress introduced during assembly. In the article, different methods of isolation were discussed and compared, and finally, the integrated thermal stress isolation structure was chosen because of its advantages of good isolation effect and simpler process. The results show that compared with nonisolated microsensors, more than 90% of the thermal stress was eliminated, and the temperature sensitivities of isolated and nonisolated resonators were 1.41 Hz/degrees C and 3.92 Hz/degrees C respectively, which confirmed that the design of isolation could weaken the influence of thermal stress effectively. With optimized parameters, the frequency characteristics of microsensors were simulated and fabrication was performed based on designed parameters. Close-loop test was performed within the pressure range of 0-265 kPa and temperature range of -40 degrees C similar to+60 degrees C and the results showed that the maximum linear fitting error of the microsensor was less than 44 Pa, the accuracy was better than 0.017% FS, and the maximum temperature hysteresis error was lower than 0.0066%. Compared with the isolation method proposed by the predecessors, this method has the advantages of simpler processes and a good isolation effect, which can provide new ideas for the design of subsequent sensors.