Developers of thin-film gas sensors benefit from heated substrate platform
The Fraunhofer Institute for Photonic Microsystems IPMS develops and
manufactures individual heatable test chips for the characterization of new gas
sensor materials. Deposited sensing layers and their application-specific
parameters, such as sensitivity and selectivity, can thus be specifically
evaluated. Customized chip designs allow the optimal and highly accurate
characterization of these thin films.
The detection of gases such as NO2, NH3, CO, H2S or volatile organic compounds (VOC)
such as acetone, formaldehyde and methanol is of great importance for the assessment
of potential health risks.
Gas sensors based on single-component metal oxides and carbon-based materials
currently suffer from limitations such as low sensitivity in the lower ppm and ppb range
as well as limited lifetime, which prevents their widespread use as high-performance
gas sensors.
Therefore, further developments are needed to achieve electrical and thermal
properties in combination with high sensitivity, fast response, high selectivity and fast
repeatability.
In the context of such research, the characterization of sensitive layers plays a decisive
role in order to be able to produce and use the materials in a targeted manner.
Fraunhofer IPMS develops and produces conductivity and single transistor structures for
the evaluation of novel materials. These substrates can be used, for example, to
characterize the electrical properties of thin-film gas sensors. These substrates can also
be used as a basis for further product developments.
"Gas sensors often need to be operated at defined temperatures. Our substrates make
it possible to control the temperature of the layers, allowing materials to be studied
easily and effectively. This includes studying stability and drift over different time
periods. In addition, the behavior in processes can be investigated already during the
deposition. We are looking for partners to further develop the technology and can also
provide chips for measurements," explains Dr. Alexander Graf, Head of the Gas
Sensors and Systems Group.
Advantages of Fraunhofer IPMS substrates
The chip substrates produced at Fraunhofer IPMS offer high-precision structures and
high-performance materials, providing a promising basis for reproducible material
evaluation in the context of R&D questions and qualification. The substrates offer
different customized designs of the electrode structures, e.g. different channel widths
and lengths on one chip, so that the ideal parameters can be used for specific
applications.
The substrates are regularly fabricated in a clean room on silicon wafers with thermal
silicon dioxide (SiO2), with other oxides such as hafnium dioxide (HfO2) available as
dielectrics.
In sensor development, the sensitive materials determine the performance of the entire
sensor. Material and process developers can apply semiconductor layers to the
substrates by solution, chemical vapor deposition (CVD), or physical vapor deposition
(PVD). Subsequent electrical characterization allows for characterization and evaluation
based on conductivity, carrier mobility, and other performance parameters. As soon as
a gas-sensitive material comes into contact with the analyte, this leads to a change in
the electrical properties.
The substrates from Fraunhofer IPMS offer a simple way to record these changes. The
sensor materials can be evaluated with respect to sensitivity and drift and then
optimized, e.g. by adjusting the deposition parameters. Due to the wafer-level
manufacturing technology, the substrates are also an interesting basis for productoriented
development.
The test structures can be easily contacted and measured with the specially developed
prober.
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About Fraunhofer IPMS
Fraunhofer IPMS is one of the leading international research and development service
providers for electronic and photonic microsystems in the application fields of intelligent
industrial solutions and manufacturing, medical technology and health, and mobility. In
two state-of-the-art clean rooms and with a total of four development sites in Dresden,
Cottbus and Erfurt, the institute develops innovative MEMS components and
microelectronic devices on 200 mm and 300 mm wafers. Services range from consulting
and process development to pilot production.
Wissenschaftlicher Ansprechpartner:
Dr. Alexander Graf - alexander.graf@ipms.fraunhofer.de
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