Single-wafer die-level fusion bonding process for multi-layer devices

Single-wafer die-level fusion bonding (SDFB) process is proposed, which can reduce the mask number and fabrication time in the prototype research of multi-layer fusion bonding devices. The conception and scheme are illustrated using micro gas turbine of MIT as an example. The techniques to etch different mask and depth in a single-wafer are listed and analyzed. The alignment compensation mechanism in the SDFB is also discussed which can avoid the photolithography misalignment and improve the precision between key layers. The advantages and disadvantages of SDFB are analyzed in detail. The feasibility of the scheme is verified by the experiment. Besides micro gas turbine of MIT, the SDFB process can also be used in other multi-layer fusion bonding devices such as ultra thick proof mass inertial sensors, multi-layer fluidic devices, etc.