Centro Materiali e Microsistemi

Trento, Italy

Centro Materiali e Microsistemi

Trento, Italy
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Dapor M.,Centro Materiali e Microsistemi | Dapor M.,University of Trento | Ciappa M.,ETH Zurich | Fichtner W.,ETH Zurich
Journal of Micro/Nanolithography, MEMS, and MOEMS | Year: 2010

The main scattering mechanisms governing the transport of electrons in PMMA in an energy domain ranging from the energy of the primary electron beam down to few hundreds of meV are identified. A quantitative Monte Carlo model for the emission of secondary electrons is developed to be applied for critical dimensions extraction from highresolution scanning electron microscopy (SEM) images. Selected results are presented, which demonstrate the accuracy of the proposed approach. © 2010 Society of Photo-Optical Instrumentation Engineers.

Koschik A.,ETH Zurich | Ciappa M.,ETH Zurich | Holzer S.,ETH Zurich | Dapor M.,Centro Materiali e Microsistemi | And 2 more authors.
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2010

Besides the use of the most sophisticated equipment, accurate nanometrology for the most advanced CMOS processes requires that the physics of image formation in scanning electron microscopy (SEM) being modeled to extract critical dimensions. In this paper, a novel Monte Carlo simulation code based on the energy straggling principle is presented, which includes original physical models for electron scattering, the use of a standard Monte Carlo code for tracking and scoring, and the coupling with a numerical device simulator to calculate charging effects. © 2010 Copyright SPIE - The International Society for Optical Engineering.

Laidani N.,Centro Materiali e Microsistemi | Bartali R.,Centro Materiali e Microsistemi | Micheli V.,Centro Materiali e Microsistemi | Gottardi G.,Centro Materiali e Microsistemi | Cheyssac P.,CNRS Condensed Matter Physics Laboratory
Surface and Coatings Technology | Year: 2011

The growth processes of carbon films deposited using two techniques (sputtering and RF plasma assisted chemical vapor deposition, PACVD), and the effects of stacking these films in a multilayered structure on their mechanical and adhesion properties were studied. The films deposited by the two techniques differed in composition, structure and hardness. They are termed "hard C" and "soft C" according to their synthesis process, sputtering and PACVD respectively. By means of stress measurements and angle-resolved X-ray photoelectron spectroscopy, the growth mechanism of the films was characterized when they were deposited on a silicon substrate and when one kind of carbon film was deposited onto the other kind, in order to simulate a multi-layer film formation. This study evidenced the effect of converting the individual layer surfaces into interfaces when building a multilayer film. On one hand, this conversion appeared to increase the compressive stress of the multilayer films for the lowest periodicity (14. nm and 7. nm of half-period). On the other hand, a strong correlation between the stress resulting from multilayering and the film elasto-plastic properties was found. A hardening effect, put in evidence by applying a nano-indentation "plasticity index", was obtained for the most layered films (i.e. with the lowest modulation period) and this effect is discussed in relation with the existing models for multi-layer strengthening. The film adhesion to polyethylene terephtalate (PET) substrates was investigated. A beneficial effect of multi-layering on film adhesion was significant only when the half-width period went down to 14. nm and 7. nm. The adhesion improvement cannot be related to a reduced internal stress, since the most stressed films were also the most adherent. Instead the compressive stress found in the films with the lowest periodicity is thought to induce a stronger bonding of the soft C layer (polymer-like) to the PET substrate and to the hard C layers, through chain entanglement across the interface. © 2011 Elsevier B.V.

Mulloni V.,Centro Materiali e Microsistemi | Iannacci J.,Centro Materiali e Microsistemi | Bartali R.,Centro Materiali e Microsistemi | Micheli V.,Centro Materiali e Microsistemi | And 3 more authors.
Microsystem Technologies | Year: 2012

In RF-MEMS switches many reliability issues are related to the metal contacts in the switching area. The quality of this contact strongly influences switching failures due to wear, adhesion and stiction. Gold is widely used as contact material, but is a soft metal. Contact hardness can be improved preserving good conductivity and chemical inertness alternating gold layers with thin layers of other metals. A detailed study of mechanical, electrical and morphological properties of gold-chromium, gold-platinum and gold-palladium multilayers is presented and discussed. Annealing treatments modify hardness values, but a careful choice of the alloying metal is essential because hardness is reduced upon exposure to plasma ashing, a very frequent microfabrication process. This treatment also increases contact roughness, deteriorating the contact surface. Platinum is the only metal tested that is unaffected by plasma oxidation, and it also reduces the diffusion of chromium adhesion layer on the contact surface. © Springer-Verlag 2012.

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