Nanomechanical and nanotribological characterizations for reliability design of MEMS resonators (NARDEMS)
Project objectives
WP1- MEC: Mechanical Characterization

O1. MEMS failures causes, MEMS materials and MEMS technologies:
At begin of project documentation activities about MEMS materials properties, MEMS technologies and classification of them as function of their impact on MEMS failures causes are developed. Meetings with international MEMS companies and research institutes are organized to implement the project goal in MEMS Community. At the end of this objective, a project WEB page is opened and an e-database are started. This novel concept is useful for MEMS Community because the MEMS designers and manufacturers will be able to on-line access and consult of the project results, to discus them and to participate to the project development.

O2. Theoretical approach and modeling (including optimization) of MEMS mechanical behavior:
Analytical models of the mechanical response of MEMS resonators under different loadings and relations to compute their mechanical properties as stiffness, Young modulus, stress and strain are developed considering the multiphysics coupling between the acting energy and the mechanical behavior of resonator structure. Fatigue analysis models (with high interests for MEMS designers) are developed to estimate the in-use lifetime of MEMS resonators. Modeling and optimization of MEMS resonator structures also are performed. The theoretical formulas, after experimental validations will be provided on the project WEB page. Dissemination activities of the O2 results consider: 1 paper published in ISI Journals (J of Microsystem Technologies) and participation at 2 ISI Conferences (EuroSimE 2012 and DTIP 2012).

O3. Experimental investigations of MEMS mechanical properties:
The measurement of the mechanical properties at micro/nano-scale is a big interest for MEMS researchers because the relative inaccuracy of these properties often leads to a functional failure - due to inaccurate material properties. In this project accurately measurements of the mechanical properties of MEMS resonators using specific equipments (as AFM, Nanoidenter, Vibrometer Analyzer etc.) are performed. The investigated mechanical properties of MEMS resonators are: stiffness, modulus of elasticity, strain, ultimate stress and strength. Ductile and soft (polymers) materials used in MEMS are theoretically and experimentally investigated to estimate their mechanical properties. A big interest is dedicated to fatigue analysis of MEMS materials which represent a novel and an actually research activity in MEMS Community. Dissemination activities of the O3 consider: 2 papers published in ISI Journals (J of Micromech & Microeng, J of MEMS) and participation at 2 ISI Conferences (SME 2013 and DTIP 2013).

WP2- TRIB: Tribological Characterization

O4. MEMS morphological analysis and nanofriction measurements:
Surface investigations are performed to characterize the MEMS structures and thin films. The morphological characterizations, the roughness and flatness measurements, and the surface energy estimation - with big influences on stiction - are developed. The comparison analysis between the macroscale value of friction coefficient and its micro/nano-scale values are determined and provided on the project WEB page. This is very helpful and is asked by the MEMS designers, especially when the micro/nano-devices with direct contact between element (as microengines or switches) are designed. Dissemination activities of the O4 results consider: 1 paper published in ISI Journals (Tribology Letter) and organization of seminaries with students and PhD students.

O5. Pull-in analysis in MEMS resonators:
The behavior of the investigated MEMS resonators at pull-in position, which is influenced by the material properties, is investigated for samples under electrostatic actuation. The pull-in position (where the electrostatic force equals to the mechanical force of beam) has a big influence on stiction. Very often the MEMS resonators collapse because the acting energy is too high, the beam deflects more than the pull-in position and sticks to substrate. Dissemination activities of the O5 results consider: 1 paper published in ISI Journals (J Sensors & Actuators) and participation of one conference (MEMS Conference 2013).

O6. Stiction analysis in MEMS resonators:
One of the main failure causes of MEMS resonators is stiction when the resonant beam collapses to substrate. More and more research activities are dedicated to avoid this effect. The influences of surfaces parameters, material properties and geometrical configuration of MEMS resonators on stiction are determined and recommendations to avoid this effect are provided on the project WEB page. Dissemination activities of the O6 results consider: 1 paper published in ISI Journals (J Reliability Engineering and System Safety) and participation of 2 International Conferences in 2013. Additionally, a workshop is planned to be organized at the project host institute with MEMS specialists from industries and research institutes.

WP3- PROT: Prototype Development

O7. Design and fabrication of a reliable MEMS resonator prototype:
Based on the results from the mechanical and tribological characterizations, a prototype of a reliable MEMS resonator is designed and fabricated. Considering the vast range of MEMS resonators applications, this project will have a big echo in MEMS Industry because a reliable product is developed.

O8. Prototype testing:
In-situ testing of the reliable MEMS resonators is performed to estimate its lifetime and the accuracy in response. If necessary, a go-back procedure to the WP1 and WP2 is considered to improve the prototype functionality. Dissemination activities of the O7 and O8 results consider: 2 paper published in ISI Journals (J Risk Analysis and J of MEMS) and participation of 2 International Conferences in 2014.

O9. Industrial implementation:
At the end of project, different activities are performed to disseminate and implement the project results. A e-database with mechanical and tribological properties of MEMS materials and recommendations of their use in MEMS resonator applications are provided. Collaboration with Nokia Company from Cluj-Napoca is considered to implement the MEMS resonator in their devices. Dissemination activities of the O9 results consider: reports and e-brochures which will be distributed to the MEMS manufacturers and designers; meetings and presentation of the project results at different international companies.
Proiect finantat de UEFISCDI 
Program Resurse Umane - Proiecte tip TE