Application Of Atomic Layer Deposition Technology In Preparation Of Anti-adhesive Films For IoT Sensors

"Internet of Things(IoT)" is a new engine that leads the development of the global electronic information industry.In the past few years,the market size and trade scale of the IoT and IoT sensors has been increasing rapidly.IoT sensors have new requirements for manufacturing processes due to their application scenarios and special structures,such as MEMS accelerometer and gyroscope,called inertial sensors,which contain mass blocks of movable cantilever beams.For these microstructures with high surface area/volume ratio,the influence of surface forces on microstructures increases significantly.The surface forces of microstructures mainly include capillary gravity,electrostatic force,van der Waals force and hydrogen bond.In the process of corrosion,cleaning and drying of microstructure,the surface tension of liquid in micro structure causes capillary force,and excessive capillary force will lead to adhesion of movable structure.By decreasing the surface energy of microstructure surface,the van der Waals force of microstructure surface can be significantly reduced and the probability of adhesion can be reduced.There are two kinds of film in the application of reducing surface energy shows great potential:(1)Atomic Layer Deposition(ALD)film;(2)self-assembled monomolecular film.However,ALD films control the arrangement of Atomic Layer in order by the surface reaction after the previous deposited Layer.The coating method can form high-quality films on the most complex nano-scale geometric shapes.Self-assembled monolecular membrane(SAM)can spontaneously assemble molecules in the system into an ordered structure without external interference.In the process of self-assembly thin film,no special intervention is required.It is a process in which atoms,molecules,molecular polymers and matrix materials automatically combine to form orderly functional entities.Organic functional molecules are formed spontaneously by the physical and chemical interactions between molecules and their matrix materials.The SAM film is ordered molecular layers with stable heat and regular arrangement.Among them,fluoroorganosilane has a wide surface energy,high heat resistance,self-decontamination,anti-friction,anti-adhesion and antibacterial properties,and has been widely used.The main work and innovative results of this paper are as follows:(1)Al2O3 thin films were prepared by atomic layer deposition with ALD-200P device.The film thickness uniformity,chamber particles,film forming consistency and hydrophobicity of Al2O3 thin films were studied.It was found that the uniformity of Al2O3 thin films was related to the number of cycles of deposition,with chamber particles between 50 and 200.At the same time,deep groove etched sample and MEMS sensor silicon wafer were used to deposit 500 cycles,and it was found that Al2O3 thin film had a good consistency of film thickness.Finally,the surface energy of Al2O3film was indirectly evaluated through the water contact Angle test,and it was found that Al2O3 film was not an ideal anti-stiction material.(2)The controlling factors of sam thin film process were analyzed,and the ALD-100p atomic layer deposition equipment was reformed.The SAM film deposition process was successfully achieved on the ALD equipment,and the FDTS self-assembled monolayers were prepared.The hydrophobicity of FDTS self-assembled monomolecular thin film is independent of deposition time,deposition temperature,ratio of precursors and other factors.The experiments showed that the water contact Angle of FDTS monomolecular self-assembled thin film decreased sharply with the baking temperature of FDTS monomolecular self-assembled thin film increasing.In order to solve the problem of the thermal stability of FDTS monomolecular self-assembled thin film,SiCl4/H2O deposition technology was studied,and Al2O3/SixOy/FDTS composite membrane with SixOy as seed layer was found to have good thermal stability.In the case of baking temperature of 500?,the water contact Angle of Al2O3/SixOy/FDTS composite thin film is still>100°.It is proved that Al2O3/SixOy/FDTS composite film is an ideal anti-stiction film which is used in wafer level packaging field.