DocumentCode :
1159482
Title :
Leakage current modeling of test structures for characterization of dark current in CMOS image sensors
Author :
Loukianova, Natalia V. ; Folkerts, Hein Otto ; Maas, Joris P V ; Verbugt, Daniël W E ; Mierop, Adri J. ; Hoekstra, Willem ; Roks, Edwin ; Theuwissen, Albert J P
Author_Institution :
Philips Semicond. Imaging, Eindhoven, Netherlands
Volume :
50
Issue :
1
fYear :
2003
fDate :
1/1/2003 12:00:00 AM
Firstpage :
77
Lastpage :
83
Abstract :
In this paper, we present an extensive study of leakage current mechanisms in diodes to model the dark current of various pixel architectures for active pixel CMOS image sensors. Dedicated test structures made in 0.35-μm CMOS have been investigated to determine the various contributions to the leakage current. Three pixel variants with different photodiodes-n+/pwell, n+/nwell/p-substrate and p+/nwell/p-substrate-are described. We found that the main part of the total dark current comes from the depletion of the photodiode edge at the surface. Furthermore, the source of the reset transistor contributes significantly to the total leakage current of a pixel. From the investigation of reverse current-voltage (I-V) characteristics, temperature dependencies of leakage current, and device simulations we found that for a wide depletion, such as n-well/p-well, thermal Shockley-Read-Hall generation is the main leakage mechanism, while for a junction with higher dopant concentrations, such as n+/p-well or p+/n-well, tunneling and impact ionization are the dominant mechanisms.
Keywords :
CMOS image sensors; dark conductivity; impact ionisation; integrated circuit modelling; integrated circuit testing; leakage currents; photodiodes; tunnelling; 0.35 micron; CMOS test structures; active pixel CMOS image sensors; current-voltage characteristics; dark current characterization; impact ionization; leakage current mechanisms; leakage current modeling; photodiode edge depletion; photodiodes; pixel architectures; reset transistor source; reverse I-V characteristics; thermal Shockley-Read-Hall generation; tunneling; CMOS image sensors; Character generation; Dark current; Diodes; Leakage current; Photodiodes; Pixel; Semiconductor device modeling; Temperature dependence; Testing;
fLanguage :
English
Journal_Title :
Electron Devices, IEEE Transactions on
Publisher :
ieee
ISSN :
0018-9383
Type :
jour
DOI :
10.1109/TED.2002.807249
Filename :
1185166
Link To Document :
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