Analysis of 320X240 uncooled microbolometer focal plane array ...

27reflection (AR) coated Ge window which transmits 98% of in-band IR signal. The heightof the package is less than 0.5 inches, and lateral dimensions are 1.5 inches.2.3 FabricationAs mentioned before, one of the advantage of the microbolometer its production processcompatibility with the standard silicon IC process. VOx thermal isolation structure arraysare co-deposited on top of the ROIC wafer using standard silicon IC thin film processing.Through the removal of the sacrificial layer between the thermal isolation structures andthe ROIC at the end of the fabrication process, high level of thermal isolation is achieved.The fabrication of the microbolometer involves micromachining techniques. Thesimplified microbolometer fabrication step are described below [9].1. All the necessary readout electronics, including transistors and metal interconnections,are imbedded in a monolithic silicon wafer.2. Sacrificial layer islands are deposited on top of the readout electronic.3. Deposit supporting bridge material (silicon nitride).4. Deposit metal connection for the detecting material.5. Deposit detector (thermal mass) material (vanadium oxide).6. Deposit supporting bridge material (silicon nitride).7. Etch away the sacrificial layer islands.