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Proceedings Paper

Characterization of spectral optical responsivity of Si-photodiode junction combinations available in a 0.35μm HV-CMOS technology
Author(s): A. Kraxner; E. Wachmann; I. Jonak-Auer; J. Teva; J. M. Park; R. Minixhofer
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Paper Abstract

The 0.35μm HV-CMOS process technology utilizes several junctions with different doping levels and depths. This process supports complete modular 3V and 5V standard CMOS functionality and offers a wide set of HV transistor types capable for operating voltages from 20V to 120V made available with only 2 more mask adders [1]. Compared to other reported integration of photo detection functionalities in normal CMOS processes [2] or special modified process technologies [3] a much wider variety of junction combinations is already intrinsically available in the investigated technology. Such junctions include beside the standard n+ and p+ source/drain dopings also several combinations of shallow and deep tubs for both p-wells and n-wells. The availability of junction from submicron to 7μm depths enables the selection of appropriate spectral sensitivity ranging from ultraviolet to infrared wavelengths. On the other side by appropriate layouts the contributions of photocurrents of shallower or deeper photo carrier generation can be kept to a minimum. We also show that by analytically modelling the space charge regions of the selected junctions the drift and diffusion carrier contributions can be calculated with a very good match indicating also the suppression of diffusion current contribution. We present examples of spectral responsivity of junction combinations optimized for peak sensitivity in the ranges of 380-450nm, 450-600nm or 700-900nm. By appropriate junction choice the ratios of the generated photo currents in their respective peak zones can exhibit more than a factor of 10 compared to the other photo diode combinations. This enables already without further filter implementation a very good spectral resolution for colour sensing applications. Finally the possible junction combinations are also assessed by the achievable dark current for optimized signal to noise characteristic.

Paper Details

Date Published: 22 May 2013
PDF: 11 pages
Proc. SPIE 8767, Integrated Photonics: Materials, Devices, and Applications II, 87670P (22 May 2013); doi: 10.1117/12.2017540
Show Author Affiliations
A. Kraxner, austriamicrosystems AG (Austria)
Technische Univ. Graz (Austria)
E. Wachmann, austriamicrosystems AG (Austria)
I. Jonak-Auer, austriamicrosystems AG (Austria)
J. Teva, austriamicrosystems AG (Austria)
J. M. Park, austriamicrosystems AG (Austria)
R. Minixhofer, austriamicrosystems AG (Austria)


Published in SPIE Proceedings Vol. 8767:
Integrated Photonics: Materials, Devices, and Applications II
Jean-Marc Fédéli; Laurent Vivien; Meint K. Smit, Editor(s)

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