PORTEFEUILLE

This project aims at the development of micromechanical and microoptical components made of pure synthetic crystalline diamond by exploiting a novel processing method, based on advanced microelectronics manufacturing technologies. The unique mechanical properties of diamond include extreme hardness and fracture strength as well as the highest known elastic modulus of any material, making it an extremely interesting material for novel components such as micromechanical gears, as for example used in mechanical watches. In combination with the optical effects of diamond, including fancy colors or chromatic dispersion due to the high index of refraction, the esthetics in such micromechanical assemblies will further be enhanced. The extraordinary optical material properties will equally find direct application in micro-optical elements, for example as optical windows or optical components in high-power laser systems.

The proposed manufacturing approach is fundamentally different from the traditional diamond processing methods based on laser cutting and fine polishing. The elementary process hereby is based on oxygen plasma etching, which selectively oxidizes the carbon atoms of the diamond crystal in a precisely controlled manner, literally burning the diamond. This advanced manufacturing process will allow to produce arbitrarily shaped planar features made out of pure synthetic diamond, with a targeted micrometer precision. With such a precise manufacturing method, precision micromechanical parts and microoptic components can be fabricated in single crystalline diamond.

In a first phase, the project has resulted in a procedure for Deep Reactive Ion Etching (DRIE) of Single Crystalline Diamond, enabled by the development of a microfabrication process using a multi-layer hard mask and a high power inductively coupled oxygen plasma etch. This achievement demonstrates for the first time the possibility to fully etch through >150 micrometer thick single crystalline diamond substrates. With near vertical sidewalls and a precision of a few micrometers, this is a major step towards the project goals for fabrication of micromechanical and micro-optical components in single crystalline diamond.
 
By adjusting the parameters of the etch process, the project partners have further fabricated diffraction gratings in single crystalline diamond. The particular V-groove shape of the gratings is defined by the crystal planes of the single crystalline diamond, allowing in principle atomically smooth surface qualities. This new type of gratings is expected to find applications in high power laser and spectroscopy applications..

In the final stage of the project, fully released mechanical watch components were demonstrated. The sidewalls of the parts were characterized by SEM and AFM, revealing angles of 83° to 92° and a roughness better than 200 nm rms, which is 5 to 50 times smoother than values obtained by laser cutting (Manuscript accepted for publication).

In view of these promising results, the project will continue as an Innosuisse funded innovation project, in collaboration with Lake Diamond. The specific goals are to improve the process (sidewalls angle and roughness, yield, fidelity) and develop a commercial offering of custom high precision micro-mechanical components in single crystal diamond by parallelizing all process steps for increased throughput.

Adrien Toros, Marcell Kiss, Teodoro Graziosi, Hamed Sattari, Pascal Gallo and Niels Quack, Precision Micro-Mechanical Components in Single Crystal Diamond by Deep Reactive Ion Etching, Nature Microsystems & Nanoengineering, 4, 12, 2018. DOI: 10.1038/s41378-018-0014-5;
Adrien Toros, Teodoro Graziosi, Marcell Kiss, Hamed Sattari, Christophe Galland, Niels Quack, “Fabrication and transfer of thin single crystal diamond membranes”, 29th International Conference on Diamond and Carbon Materials, 2 6 September 2018, Dubrovnik, Croatia.;
Adrien Toros, Marcell Kiss, Teodoro Graziosi, Hamed Sattari, Pascal Gallo, Niels Quack, "Fabrication of thick and high-aspect ratio components in single crystalline diamond by deep reactive ion etching", 28th International Conference on Diamond and Carbon Materials (DCM), 3 - 7 September 2017, Gothenburg, Sweden;
Marcell Kiss, Teodoro Graziosi, Niels Quack, "Demonstration of V-groove diffraction gratings in single crystal diamond", 28th International Conference on Diamond and Carbon Materials (DCM), 3 - 7 September 2017, Gothenburg, Sweden.

Printed Media
La Liberté, 19.06.2018, «Innovation de l’EPFL
24 heures, 19.06.2018, «Innovation – Des mécanismes en diamant», Page 17
Tribune de Genève – 19.06.2018 – «Innovation – Des mécanismes en diamant», Page 17
Bilan – 04.07.2018 – «Le diamant de labo, plus vrai que nature?», Page 14

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