Integrated X-ray and Charged Particle Active Pixel CMOS Sensor Arrays using Epitaxial Silicon Sensitive Region.

Kleinfelder, S. ; Bichsel, H. ; Bieser, F. ; Matis, H. S. ; Rai, G. ; Retiere, F. ; Weiman, H. ; Yamamoto, E.

Technical Information Center Oak Ridge Tennessee

关键词: Pixels;    CMOS;    Silicon;    Signal to noise ratio;    X-ray sources;   

RP-ID  :  DE2004834920

学科分类：工程和技术（综合）

美国|英语

来源: National Technical Reports Library

【 摘 要 】

Integrated CMOS Active Pixel Sensor (APS) arrays have been fabricated and tested using X-ray and electron sources. The 128 by 128 pixel arrays, designed in a standard 0.25 micron process, use a approximately 10 micron epitaxial silicon layer as a deep detection region. The epitaxial layer has a much greater thickness than the surface features used by standard CMOS APS, leading to stronger signals and potentially better signal-to-noise ratio (SNR). On the other hand, minority carriers confined within the epitaxial region may diffuse to neighboring pixels, blur images and reduce peak signal intensity. But for low-rate, sparse-event images, centroid analysis of this diffusion may be used to increase position resolution. Careful trade-offs involving pixel size and sense-node area verses capacitance must be made to optimize overall performance. The prototype sensor arrays, therefore, include a range of different pixel designs, including different APS circuits and a range of different epitaxial layer contact structures. The fabricated arrays were tested with 1.5 GeV electrons and Fe-55 X-ray sources, yielding a measured noise of 13 electrons RMS and an SNR for single Fe-55 X-rays of greater than 38.