NIST researchers develop microcalorimeter arrays using surface micromachining.

The single-pixel superconducting transition-edge sensor (TES) x-ray microcalorimeters developed at NIST enable x-ray spectroscopy with energy resolution that is 10 to 100 times better than conventional semiconductor detectors. This high-energy resolution has proven useful in a variety of applications, including x-ray microanalysis in a scanning-electron microscope. NIST researchers now have developed 64-pixel arrays of microcalorimeters to decrease data collection times, enable imaging, and provide an order of magnitude improvement in the analysis of nanoscale particle, thin films, and trace contaminants in materials.

The researchers fabricated 64 pixel arrays of TES microcalorimeters using surface-micromachining techniques. Until now, microcalorimeters always have been fabricated using bulk micromachining techniques where thermal isolation of the detector is achieved by removing the Si substrate from behind the detector, leaving the detector supported by only a thin membrane of silicon nitride. The resulting device is extremely fragile, requires complex double-sided processing, and the possible device geometries are limited. In surface micromachining, detectors are fabricated on a silicon nitride membrane "table" supported by legs on top of a solid substrate. The resulting device is robust, and the space beneath the pixel can be exploited for readout circuitry. This new processing technique will make it possible to build arrays of high-performance TES microcalorimeters for a variety of materials analysis and astronomical applications.

CONTACT: Gene Hilton, [phone]: [e-mail].