Efficient Xe Filling of MEMS Vapor Cells Empowered by Customized Triple Stack Wafer Bond Processing

Nuclear-magnetic-resonance (NMR) gyroscopes based on MEMS vapor cell technology are currently being investigated worldwide and show superior advantages over current MEMS gyroscopes. However, there are still challenges in the upscaling and further deployment of NMR gyroscopes, due to the extremely high cost of the required gases (i.e., 129Xe, 131Xe), size, and high power consumption. To tackle these bottlenecks, in this study, a miniaturized, chip-scale, and low-cost NMR gyroscope has been conceptualized and fabricated. Here, a cost-effective and scalable filling of MEMS vapor cells with Xe gas was developed via an innovative microfabrication and wafer stacking process flow. By utilizing ultra-thin glass wafers, Taiko-processed silicon wafers, and an external gas flow system integrated into the wafer bonder, a sequential anodic bonding technique is executed to create a hermetically sealed Xe gas-filled chamber at minimal Xe consumption during the filling process.