September 17, 2008

DOE Awards NSLS $2.2 Million for Advanced X-ray Detector Development

Pete Siddons

The NSLS has received a $2.2 million, three-year, renewable grant from the Department of Energy’s Office of Basic Energy Sciences to develop the next generation of advanced x-ray detectors for synchrotron radiation. The grant will allow the NSLS Detectors Section – led by physicist Pete Siddons – to explore the possibility of applying three-dimensional integration techniques for “smart” two-dimensional detectors.

Three-dimensional integration describes a method where one or more layers of active electronics on low-resistivity silicon are physically connected to a thick high-resistivity layer by some type of chemical bond. While each microelectronics layer is only a few micrometers thick, the high-resistivity fully depleted layer is several hundred microns thick to provide high quantum efficiency for x-rays. This translates into higher detector sensitivity, superior image quality, and lower acquisition times. Inter-layer connections within the electronics layers can then be made using conventional microelectronics techniques. This technology would offer much greater versatility (e.g. much smaller pixels and higher integration density) than the bump-bonding technique, and would be a valuable asset to beamlines at NSLS-II.

To explore this technique at the NSLS, Siddons said the group will focus initially on producing high-resistivity sensors capable of interfacing with the 3-D technology. The bonding techniques for 3-D integration require the bonding surfaces to be extremely flat. However, the in-house detector lab at BNL produces surfaces with significant topology. Through the introduction and development of planarizing techniques, based on industry standard methods, devices compatible with multi-layer construction will be fabricated. Later phases of the project will identify an industry partner to perform the layer bonding.