In this paper, we describe the design, fabrication, and performance of a high-T c GdBa 2 Cu3O 70 superconductor bolometer positioned on a 2-2 2-mm 2 1-m-thick silicon nitride membrane. The bolometer structure has an effective area of 0.64 mm 2 and was grown on a specially developed silicon-onnitride (SON) layer. This layer was made by direct bonding of silicon nitride to silicon after chemical mechanical polishing. The operation temperature of the bolometer is 85 K. A thermal conductance G = 3:3 1 10 05 W/K with a time constant of 27 ms has been achieved. The electrical noise equivalent power (NEP) at 5 Hz is 3.7 1 10 012 WHz 01=2 , which is very close to the theoretical phonon noise limit of 3.6 1 10 012 WHz 01=2 , meaning that the excess noise of the superconducting film is very low. This bolometer is comparable to other bolometers with respect to high electrical performance. Our investigations are now aimed at decreasing the NEP for 84-m radiation by further reduction of G and adding an absorption layer to the detector. This bolometer is intended to be used as a detector in a Fabry-Perot (FP)-based satellite instrument designed for remote sensing of atmospheric hydroxyl. [252] Index Terms-Bolometer, chemical mechanical polishing, high TC superconductor, infrared detector, noise properties, wafer bonding.