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ANR funded project

Chimie Durable – Industries – Innovation (CD2I)
Edition 2012


Development of grafting processes in supercritical CO2 for microsystems

Innovative processes for the manufacture of biological and environmental micro and nano-systems.

Process Development for organic molecules layers deposition on microstructured surfaces.
The MEMS sector develops promising new applications in the field of life, such as micro and nano-sensors, analyzers and lab-on-chips. Their manufacture requires realizing organic layers deposition with controlled nanometer-range thickness, in order to obtain functional surfaces (sensitive part of the sensors, biocompatibility, wetting, etc.). To achieve this, laboratories are looking for new deposition processes of functional organic molecules on the surface of these small size components and their very complex geometries. Current techniques, such as solvents or vacuum deposition, provide only partial solutions and even insufficient in some cases. It is proposed to develop a deposition technique in supercritical CO2, which has the property of being a solvent with a very high diffusivity. The supercritical fluid would be able to transport non-volatile molecules at low temperature in cavities and micro-channels, what is not possible with conventional solvents. This totally new process for this application could also limit the use of solvent and reduce the amount of chemical precursors used during this step.

Prototype equipment design for deposition in supercritical CO2 and technology validation on micro and nano-systems.
This technique has been previously studied at lab-scale by partners and showed promising results. Further validation requires the achievement of a specific equipment to implement the processes with reliable reproducibility. This new equipment incorporates modules for the injection of chemical precursors in small quantities in supercritical CO2 at more than 100 bar, and a reactor designed to ensure uniform deposits on the surface of silicon discs generally used as manufacturing substrate. Process optimization is performed on blank surfaces to characterize the functional layers by infrared spectroscopy, ellipsometry, fluorescence and scanning electron microscopy. Layers characterization is carried out on different dimensions of structures, from nano to micro, for various applications: micro and nanometer-range gas sensors, as well as in vitro biological analyzer. Validation is finally conducted on prototype components, measured on test benches (gas sensors).


Two prototype equipments were built and are running in laboratory partners cleanrooms. Deposited layers in supercritical CO2 showed properties similar or even superior to the organic layers deposited by conventional methods such as
Référence du formulaire : ANR-FORM-090601-01-01 5/66
solvent or gas phase deposition. A prototype gas sensor was realized and qualified on a test bench; good results are obtained both in terms of sensitivity (detection of lower gas concentrations) and detection temperature, below 50°C.



Scientific outputs and patents

Many results were published, including work performed on catalysers or gas sensors. One paper was published in Applied Surface Science journal, oral presentations in international conferences (Trends in Nanotechnology Conf., Euromat, European Conf. On Surface Science) and national seminars. This technology was highlighted in LETI annual report, and prototype equipment was disclosed at a nanotechnology international showcase.


31° 31 Degrees

CEA Commissariat à l'energie atomique et aux energies alternatives

LAAS Laboratoire d'Analyse et d'Architecture des Systèmes


ANR grant: 505 327 euros
Beginning and duration: avril 2012 - 36 mois

Submission abstract

In a previous study, partners of the project have demonstrated feasibility and interest of an innovating grafting process of organic molecules on inorganic substrates for MEMS manufacturing.
The goal of this project is to develop a prototype equipment in order to optimize the grafting processes and define advantages and drawbacks of this technique for components with critical dimensions of different scales, from micro to nano.
The project will be focused on the conception of key elements in the prototype, whch are the precursor injection modules and the grafting reactor. Reactor design will be based on flow modelisation inside it.


ANR Programme: Chimie Durable – Industries – Innovation (CD2I) 2012

Project ID: ANR-12-CDII-0003

Project coordinator:
Monsieur PERRUT VINCENT (31 Degrees)


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The project coordinator is the author of this abstract and is therefore responsible for the content of the summary. The ANR disclaims all responsibility in connection with its content.