3DX: an X-ray pixel array detector with active edges

• Published in: IEEE transactions on nuclear science Vol. 53; no. 3; pp. 1676 - 1688
• Main Authors: Parker, S.I., Kenney, C.J., Gnani, D., Thompson, A.C., Mandelli, E., Meddeler, G., Hasi, J., Morse, J., Westbrook, E.M.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.06.2006; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 3D sensors; Active edges; Arrays; Borders; Charge; Chips; Circuits; Detectors; Electrodes; Fabrication; guard rings; insensitive edge regions; Pixels; protein crystallography; Prototypes; Pulse amplifiers; semiconductor sensors; Sensor arrays; Sensors; Silicon; silicon sensors; structural molecular biology; Synchrotrons; three-dimensional (3D) electrodes; X-ray detection; X-ray detectors; X-rays
• ISSN: 0018-9499; 1558-1578
• DOI: 10.1109/TNS.2006.873713

We are developing a prototype X-ray detection system that should be ideal for many types of synchrotron science. X-rays are captured directly in thick, high-resistivity, single-crystal, silicon pixel sensors. Unlike other X-ray detectors, which have a substantial dead area around their borders, these have "active edges"-edges formed from electrodes in the third dimension, perpendicular to the top and bottom surfaces, with full sensitivity to within a micron of the physical border. Each sensor is 0.96 mm/spl times/0.96 mm, having a 64/spl times/64 two-dimensional array of 150 /spl mu/m pixels. Behind each sensor, a custom CMOS readout chip is bump-bonded to the sensor. It provides high-speed (64/spl mu/s/full-array) readout of each pixel, with a dead time for each row, during pixel reset, of 1 /spl mu/s. On three edges, it lies completely hidden behind the sensor. A 3 mm wide region on the remaining edge of each CMOS chip contains readout circuits and connections. Here it protrudes beyond the sensor edge, but is covered by the active region of a neighboring sensor module in an array similar to that of shingles on a roof. Sensor units can be easily arrayed to cover large areas. The readout chip has 128 ADCs and, for each pixel, a charge amplifier. To save fabrication costs, the prototype readout has just 8/spl times/64 pixels. Using pulse heights, we should be able to combine signals when X-rays share charge between adjacent pixels. We have already made accurate quantum-counts of 0 to 7 X-ray events/pixel during each 64 /spl mu/s readout cycle.