Research On The Pulsed Two-phase Deposition Of Zno Hydrochemical Precursors With In-phase Coupled Heat Flux

Zinc oxide(ZnO)nanowires are important nano-functional materials and have very broad application prospects.Low-temperature hydrothermal synthesis of ZnO nanowires has the characteristics of simple process conditions,low cost,easy to realize large-area deposition and mass production,and has been widely valued.In order to deposit ZnO nanowires on more types of substrates and broaden their application,the academic community introduced the ”two-step method”,in which the preparation of the seed layer is a key step of the two-step hydrothermal method.The high-quality seed layer can reduce the lattice mismatch between the nanowire and the substrate,improve the deposition effect of the subsequent hydrothermal process,enhance the adaptability to the substrate,and thus improve the controllability of the nanowire morphology to a certain degree.The combination of ZnO nanowire functional materials and micro-electromechanical system(MEMS)technology,integrated preparation of micro-devices such as sensors with excellent performance,has become an important development direction.Although mainstream IC production lines are dominated by12 inches,domestic microelectronics OEMs currently provide 6-inch process line services for MEMS technology,such as Huahong.In order to achieve application transformation,this requires the preparation process of ZnO nanostructures to have an efficient and controllable deposition capability on the surface of 6-inch complex materials.However,for the two-step deposition of a patterned metal microelectrode substrate on a 6-inch surface,the controllable and efficient realization of the pre-phase thin film has become a technical bottleneck,and no research work has been reported at home and abroad.Under this background,on the basis of comparing the advantages and disadvantages of common thin film preparation process methods,we chose to learn from the spray thermal decomposition method,put forward new ideas,and carried out the following research work:(1)Aiming at the uniformity of the size of the pre-phase droplets,it is proposed to use the fluid quality and the effect of droplet quality screening in the gravity field to improve the uniformity of the droplet size of the atomized deposition droplets on the substrate surface;To avoid the problem of droplet condensation that cannot be evaporated quickly and affect the quality of deposition,a pulsating jet method was further proposed to maintain the surface quality and improve the deposition efficiency.(2)Aiming at the contradiction that the deposited composite structure substrate can not work at high temperature for a long time,and the deposition quality is positively correlated with the substrate temperature,a time-varying temperature control strategy coupling high-temperature pulse and deposition jet time characteristics is proposed,based on neural network system identification mode,applying the BP neural network model to the temperature control of the deposition boat,using the STM32 system as the control core to build the temperature control system of the deposition boat,collecting random control strategy-temperature correspondence data,performing neural network training,and realizing the substrate time-varying temperature control algorithm.On this basis,an automated seed layer deposition prototype system was designed and built independently.It can show good adaptability to various substrates such as ITO,carbon fiber,printed circuit board(PCB)and so on after exploring the process parameters in the later stage.Based on the system,a two-step deposition experiment of a 6-inch PCB substrate(with gold and polyimide films on the surface)was carried out.Scanning electron microscope(SEM)was used to characterize the uniformity of the nanostructures,and the statistics of the diameter of the ZnO nanowires in various regions of the substrate were measured and calculated with a standard deviation of116.36 nm.Therefore,within a certain standard deviation range,the system can initially achieve the uniform deposition of ZnO nanowires on a 6-inch substrate,which has certain potential application value.The perfect uniform deposition of ZnO nanowires on a 6-inch substrate needs to be further fumbling of the process parameters,which satisfies the needs of a variety of MEMS devices for large-scale low-temperature uniform deposition of ZnO nanowires compatible with integrated processing of microelectronics.