A new concept for CMOS-compatible fabrication of uncooled infrared focal plane arrays using wafer-scale device transfer bonding

In this paper we present a new membrane transfer bonding technology for fabrication of uncooled infrared focal plane arrays (MFPAs). The technology consists only of low temperature processes, thus, it is compatible with standard integrated circuits (ICs). In the future this technology may allow infrared detectors with high temperature annealed, high performance thermistor materials to be integrated in CMOS based uncooled IRFPAs. The infrared detectors and the ICs are processed and optimised on different wafers. The wafer with the detectors (sacrificial detector-wafer) is bonded to the IC wafer (target wafer) using low temperature adhesive bonding. The detector-wafer is sacrificially removed by etching or by a combination of grinding and etching, while the detectors remain on the target wafer. The detectors are mechanically and electrically contacted to the target wafer. Finally, the adhesive bonding material is sacrificially removed. One of the unique advantages of this technology is the ability to integrate small, high temperature annealed detectors and ICs. We have applied membrane transfer bonding to the fabrication of arrays of infrared bolometers with polycrystalline silicon thermistors. In principle, membrane transfer bonding can be applied to the fabrication of any type of free-standing transducer including bolometers, ferroelectric detectors and movable micro-mirrors.