Characterization of transfer-bonded silicon bolometer arrays

Abstract

In this paper we present the design, fabrication and characterization of arrays of boron doped polycrystalline silicon bolometers. The bolometer arrays have been fabricated using CMOS compatible wafer-level transfer bonding. The transfer bonding technique allows the bolometer materials to be deposited and optimized on a separate substrate and then, in a subsequent integration step to be transferred to the read-out integrated circuit (ROIC) wafer. Transfer bonding allows thermal infrared detectors with crystalline and/or high temperature deposited, high performance temperature sensing materials to be integrated on CMOS based ROICs. Uncooled infrared bolometer arrays with 18x18 pixels and with 320x240 pixels have been fabricated on silicon substrates. Individual pixels of the arrays can be addressed for characterization purposes. The resistance of the bolometers has been measured to be in the 50 kΩ range and the temperature coefficient of resistance (TCR) of the bolometer has been measured to be -0.52%/K. The pixel structure is designed as a resonant absorbing cavity, with expected absorbance above 90%, in the wavelength interval of 8 to 12 μm. The measured results are in good agreement with the predicted absorbance values.