Based On Bst Thin Films The Ufpa Devices Unit

In the last twenty years, the pyroelectric thin film monolithic uncooled infrared detector is the key scientific research project of the infrared detector. With thin film of pyroelectric materials technology further expanded, the pyroelectric properties of thin film materials have been continuously improved; and with the continuous development and improvement of MEMS technology, the structure of pyroelectric thin film monolithic uncooled infrared detector which is extensively researched at home and abroad, and have application prospects in the military and the civilian market currently has been optimized, and the performance also has been improved. The core component of the pyroelectric thin film monolithic uncooled infrared detector is pyroelectric thin film monolithic uncooled infrared focal plane arrays which performance is mainly affected by the performance of sensitive materials and sensitive cells insulated structure. Especially for the continuously reduction in size of the detector unit, insulation structure on the detector performance has a sighificamt effect on the pyroelectric sensitive materials. This paper with monolithic uncooled infrared detector focused on the fabrication of BST pyroelectric thin film.Based on the theoretical analysis to the performance of pyroelectric uncooled infrared detector, and comparing the pros and cons of several common insulation structures for the detector a suspended micro-bridge supported by composite film was designed. On this basis of analysis about that thin film stress affects the film floating structure, a silicon nitride film of the appropriate stress and thickness as a stress equilibrium layer and support layer was selected. The effective area of detector modules is 0.0001cm2, and the thickness of micro-bridge's composite films is less than 3um.The necessary technology-related to manufacture micro-bridge unit of detector have been studied, including the preparation of pyroelectric sensitive materials thin films, the preparation of metal electrodes graphic films and the release of micro-bridge structure. The BST thin film with self-prepared buffer layer is deposited by the mature RF sputtering in laboratory. The Pt/Ti bottom electrode and the NiCr top electrode have been made by the lift-off technique and DC sputtering, and annealing process used to optimize the performance of Pt/Ti bottom electrode which deposited in low temperature. Studying the relations on the corrosion rate and the corrosion surface roughness of TMAH etching solution and serious of corrosion parameters, select the TMAH solution which concentration is 25wt% with addition of (NH4)2S2O8 by 3g/100ml at 80℃.high temperature for corrosion. A special protection fixture was designed to protect the sensitive cells of positive substrate in the etching process, and combined with the use of the series protective glues, to avoid damage on the cells in the silicon etching process of 10 hours.A complete micro-bridge unit is successfully manufactured applying the technology above in the end, which has the complete electrode pattern of unit with sharp edges; flat corrosion surface; small stress and less than 3um equithickness of vacant part of composite films. It achieves the design requirements.Finally, an BST thin film capacitance was formed on a thin Si membrane, the D* of 9.67×10⁷cmHz^1/2W^-1 has been obtained at 305K and 135Hz, based on blackbody of 700K, testing bias of 3V, and capacitor's area of 0.0001cm².