毫米级空气轴承的结构与MEMS制造工艺研究

In order to study the structure and Micro-Electro-Mechanical System (MEMS) manufacturing process of micro air bearing (MAB) applied to micro propulsion system, on the premise of ensuring performance requirements, the compatibility of the structure with the MEMS process, especially the silicon direct bonding technique (SDB) of multilayer, is fully considered and an innovative structure with a total thickness of 1.5mm is proposed, the manufacturing process of which is also developed. Many new approaches are proposed to overcome the 3B (Bearing, Blade, Bonding) challenges for MEMS manufacturing of micro air bearing. The influence of the etching parameters on structural accuracy of bearings is investigated by means of variable experiment, the verticality of bearing side wall exceeded 89°with its roughness less than 10nm. The common defect of wet etch diffusion is eliminated, in addition, the integrity and uniformity of the blade structure are improved. The optimum process parameters for SDB of multilayer are obtained and the SDB bonding rate of three layers reached 85% through the quantitative analysis of MATLAB image processing program, which is better than previously reported results. The results show that the MEMS process can be used in the manufacture of micro air bearing, but the process compatibility must be cautiously considered in the structural design process. The bias power and chamber pressure have important influence on the verticality and roughness of the side wall of journal bearing. Besides, the etching to protection cycle must be adjusted to ensure the integrity and uniformity of the structure when etching the blades. The reduction of bonding layers and stress accumulation of silicon wafer plays an important role in improving the SDB bonding rate of multilayer.