Silicon-Copper Sealing Based on Eutectic Bonding with Ag-In Alloy

The Torr-Seal gluing method and glass frit sintering method commonly used in silicon-copper sealing is difficult to apply to ultra-high vacuum on account of its high outgassing rate and glass frit pollution for the file of vacuum. Therefore,a sealing method with excellent hermeticity and low outgassing rate is urgently needed. In this paper,a new sealing method based on Ag-In alloy for the silicon-based standard conductive element is proposed;that is,the silicon wafer is sealed to an oxygen-free copper plate by a micro-nano manufacturing process with an Ag-In alloy layer,and then connected to a vacuum test system by the flange. The structural design of oxygen-free copper plate support was optimized,and the best buffering effect of the alloy layer was verified by the ANSYS workbench. The best process parameters were found through experiments,and the background leakage rate of the sealing assembly was measured by a helium mass spectrometer. The measurement results show that the minimum background leakage rate is 7.49×10^-12 Pa·m³·s^-1 at the atmospheric upstream pressure.