Fabrication Of The Functional-structural Layer For Application In High-Temperature Thin Film Heat Flux Sensor

As the development of science and technology,the heat flux density measuringtechnology has earned more and more attention,and the heat flux sensor have also been extensively studied.The wide application of thin film technology has promoted the research of thin film heat flux sensors,which has a positive effect on thermal protection and industrial production field.Transient,high-precision heat flux is difficult to be measurd and has not been solved.At present,the transient response time of heat flux measurement is millisecond and the heat flux measurement range is mostly in the kilowatt level.In this paper,the key structure of the thin film transient heat flux sensor is studied,which are the thermal resistance layer and the thermopile layer of the sensor,aims to improve the performance of the sensor.Focusing on the fabrication of thermal resistance layer and thermopile layer,the main contents are as follows:?1?Research on the structure of the thin film flux sensor.Based on heat transfer theory and the working principle of thermocouple,a multilayer film heat flux sensor with insulating layer,thermopile and thermal barrier layer is designed.The theoretical calculations of transient response time,measurement rangeand sensitivity of the sensor were performed,which proved the feasibility of the scheme.?2?The fabrication of SiO₂ heat insulation layer by lectrohydrodynamic jet?E-jet?was studied.The stable suspension of SiO₂ was deposited on the silicon substrate by E-jet deposition.The influences of the deposition height and line-to-line pitch of the scanning were studied.It was concluded that reducing E-jet deposition height and optimizing of the line-to-line pitch contributed to less film cracks and density improvement.The impact of the way of heat treatment on SiO₂ was also studied and discussed.Compared with PECVD deposition of SiO₂ film,the thermal conductivity of SiO₂ film deposited by E-jet is 18.7%lower than that of PECVD,E-jet deposition showed its advantage as a heat flux sensor thermal barrier layer.?3?The preparation process of the thermopile was studied,and the lift-off process with a higher precision was used.A thermopile layer was prepared on the surface of the substrate by photolithography process and sputter coating.The substrate was roughened by etching,and the effect of substrate surface roughness on the bonding force of the film was studied.The roughness of silicon substrate was 116 nm when the etching time was 25 minutes,which is 58 times that of the unetched surface.The bonding force between the substrate roughened and the non roughened substrate was tested.The bonding force increased from 4.3N to 13.1N andincreased by 204%,which indicates that the roughened substrate is more conducive to the preparation of thermopile,so the roughened substrate is more conducive to the preparation of thermopiles.