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Study of a Fabrication Process and Characterization of One Dimensional Array of Un-cooled Micro-bolometers Based on Germanium Films Deposited by Plasma

Published online by Cambridge University Press:  01 February 2011

Mario Moreno ,
Andrey Kosarev ,
Alfonso Torres  and
Roberto Ambrosio
Mario Moreno
Affiliation:
mmoreno@inaoep.mx, Institute National of Astrophysics, Optics and Electronics, Electronics, L.E. No. 1 Tonanzintla., Puebla, 72840, Mexico
Andrey Kosarev
Affiliation:
akosarev@inaoep.mx, INAOE, Microelectronics, L.E. No. 1 Tonanzintla Puebla., Puebla, 72840, Mexico, 52 222 2663100 ext. 1409, 52 222 2470517
Alfonso Torres
Affiliation:
atorres@inaoep.mx, Institute National of Astrophysics, Optics and Electronics, Electronics, L.E. No. 1 Tonanzintla., Puebla, 72840, Mexico
Roberto Ambrosio
Affiliation:
rambro@inaoep.mx, Institute National of Astrophysics, Optics and Electronics, Electronics, L.E. No. 1 Tonanzintla., Puebla, 72840, Mexico
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Abstract

In our previous works we have studied the fabrication process and characterization of single cell micro-bolometers based on germanium thin films deposited by low frequency (LF) PECVD technique at low temperature and fully compatible with the IC fabrication technology. We have demonstrated promising properties of those devices for further development of IR imaging systems.

In this work we report the study of a fabrication process and characterization of one dimensional array of 32 un-cooled micro-bolometers. We have used surface micro-machining techniques for the array fabrication onto a silicon wafer. The micro-bolometers in the array have a “bridge type” configuration, in which a SiNx supporting film is suspended 2.5 μm from the substrate by two legs forming the bridge in order to provide sufficient thermo-isolation for thermo-sensing layer, which is deposited by LF PECVD over it. The a-GexSiy:H film used in this devices showed high activation energy Ea= 0.34 eV, providing high thermal coefficient of resistance, TCR=α=0.043 K-1 and improved but still high resistance. We studied the effect of include boron in the a-GexSiy:H film deposition process in order to reduce its undesirable high resistance and we used this layer (a-GexBySiz:H) as thermo-sensing film in the micro-bolometers arrays also. The active area of the cells in the array is Ab=70×66 μm2 and the area of the array including interconnection lines and pads is A=1600×3120 μm2. The temperature dependence of conductivity σ(T), current-voltage characteristics I(U) and spectral noise density have been measured in the micro-bolometers in the array in order to characterize and compare their performance characteristics, such as responsivity and detectivity.

Keywords

IrsensorGe
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 989: Symposium A – Amorphous and Polycrystalline Thin-Film Silicon Science and Technology-2007 , 2007 , 0989-A19-01
Copyright
Copyright © Materials Research Society 2007

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References

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