Fabrication and characterization of infrared and sub-mm spiderweb bolometers with low-T/sub c/ superconducting transition edge thermometers

Spiderweb bolometers with a superconducting transition edge thermometer combine a high sensitivity and absorption efficiency for far infrared and sub-mm radiation with a low susceptibility to high energetic particles. They are among the most promising detectors today for future astronomy applications. In this paper we present our fabrication process for a fully integrated bolometer consisting of absorber, thermometer and suspension structure, based on micromachining of a silicon nitride membrane and various thin film deposition and etching steps. The optimization of Ti/Au transition edge thermometers is described, as well as electrical measurements on a fully integrated bolometer, indicating an electrical noise equivalent power of 2/spl times/10/sup -17/ W//spl radic/Hz at an operating temperature of 270 mK.