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CIP (cleaning-in-place) stability of AlGaN/GaN pH sensors

 
: Linkohr, S.; Pletschen, W.; Schwarz, S.U.; Anzt, J.; Cimalla, V.; Ambacher, O.

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Journal of biotechnology 163 (2013), Nr.4, S.354-361
ISSN: 0168-1656
ISSN: 1389-0352
ISSN: 1873-4863
Englisch
Zeitschriftenaufsatz
Fraunhofer IAF ()
ISFET; pH sensor; CIP test; passivation

Abstract
The CIP stability of pH sensitive ion-sensitive field-effect transistors based on AlGaN/GaN heterostructures was investigated. For epitaxial AlGaN/GaN films with high structural quality, CIP tests did not degrade the sensor surface and pH sensitivities of 55-58 mV/pH were achieved. Several different passivation schemes based on SiOx, SiNx, AlN, and nanocrystalline diamond were compared with special attention given to compatibility to standard microelectronic device technologies as well as biocompatibility of the passivation films. The CIP stability was evaluated with a main focus on the morphological stability. All stacks containing a SiO2 or an AlN layer were etched by the NaOH solution in the CIP process. Reliable passivations withstanding the NaOH solution were provided by stacks of ICP-CVD grown and sputtered SiNx as well as diamond reinforced passivations. Drift levels about 0.001 pH/h and stable sensitivity over several CIP cycles were achieved for optimized sensor structures.

: http://publica.fraunhofer.de/dokumente/N-223171.html