Memscap (France)

This paper presents a study on multiphysics softwares reliability provided by COMSOL and ANSYS. The goal is to give an overview about the fundementals of how to set up RF simulations, mechanical contact and residual stress through three examples choosen as the main keypoints in order to make in the future an highly coupled model of the RF Mems switches packaging.

This article addresses the reliability of micro-machined structures on membrane. RF filters on membrane have been used. The aim of the present work is to prove that these micro-electro-mechanical structures (MEMS) possess an adequate behavior with respect to spatial constraints. We studied the S parameter evolution in function of the temperature and the mechanical reliability towards shocks and vibration. The structures show a very good resistance towards these preliminary constraints.

Micromachined RF-filters for Millimeter wave communications are expected to replace the actual bulky off-chip filters since they offer high performances at low cost. Nevertheless, their large aspect ratio between area (several mm/sup 2/) and their thickness (a few microns) may make them sensitive to mechanical stress such as vibrations or shocks. In this paper, we focus on their mechanical characteristics. The studied filters are built on a thin SiO/sub 2//Si/sub x/N/sub y/ dielectric membrane and the signal lines are in gold. This composition of material makes the analytical approach rapidly complex. So, in counterparts, we ran FEM simulations to study the influence of process parameters such as stress on flexion modes. Then, we measured by vibrometry the natural resonant frequency of several filter sizes (from 1 mm/sup 2/ up to 70 mm/sup 2/) and compared results with previous simulations. Finally, we applied at die level, standard procedures of shock and vibration used for space qualification. All the membranes withstood the tests without structural damage.

The purposes of failure analysis are to localize the failure site, to establish the type of failure and to understand the failure mechanism. Some MEMS, such as Analog Device's accelerometer ADXL501, are confronted with stiction problems. Either we get around the problem by creating designs, which are not subject to this type of failure, or we try to understand its mechanism. The residual stresses have an important role in the stiction because according to the configurations of the structures, they can stiffen beams and so oppose this failure, or amplify it by bending it towards underlying mechanical elements. That's why we carry an interest in the residual stresses to understand and counteract this type of failure. Besides, the residual stresses have also repercussion on properties such as fatigue, fracture, friction, which are at the origin of other types of failure. In this article, we attempt to set up a method to qualify and quantify the residual stresses in the different layers of the MUMP's process. The role of the residual stresses will be studied through the dimensions of the layers, their types, their coating temperatures to afford a feedback between the designers and the manufacturers. We will use a failure example in MEMS, the variable capacitance, to introduce the impact of the residual stress, on the nominal working of the mechanisms. To understand the failure of the capacitance, we chose to build test structures made of cantilevers to show the influence of the residual stresses of the different layers of multilayers. So the paper will be dedicated to the implementation of test structures and theoretical elements appropriate for revealing and determining the failure due to residual stresses.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

High volume ICs production companies (telecom, etc) show a growing interest in MEMS components, especially RF and optical ones. Prototypes of integrated inductances and optical switches demonstrate very promising performances. The transition to the high volume production implies the development of Design For Manufacturability (DFM) tools featured to handle MEMS specific processes and related problems such as yield loss due to process dispersion. These tools must be part of a MEMS dedicated CAD environment. This paper presents results of what could be yield enhancement using usual statistical optimization tools and methods, and a new approach currently developed by MEMSCAP and LIRMM, based on response variability minimization.

The paper firstly presents the two main initiatives and programs in Europe for stimulating research and development in the microsystems field. They consist of the new phase launched in 1999 by the European commission within IST in the 5th FWP Frame Work Programme and the new strategic program Eurimus labelised in 1998 within the Eureka frame. The next section presents NEXUS the European network of excellence for microsystems, its main organisation based on USCs User Supplier Clubs and the result of the two task forces market investigations and road map. The third section is dedicated to EUROPRACTICE which aims at providing access to microsystems foundry services for European small and medium sized companies. As a conclusion of this presentation the last chapter of the paper presents the European main success stories in different field of applications such as automotive, IPC industrial process control, aeronautics, CAD tools and Ips, (bio)medical and household appliances.