Mechanical characterization of polysilicon MEMS: A hybrid TMCMC/POD-kriging approach

Microscale uncertainties related to the geometry and morphology of polycrystalline silicon films, constituting the movable structures of micro electro-mechanical systems (MEMS), were investigated through a joint numerical/experimental approach. An on-chip testing device was designed and fabricated to deform a compliant polysilicon beam. In previous studies, we showed that the scattering in the input-output characteristics of the device can be properly described only if statistical features related to the morphology of the columnar polysilicon film and to the etching process adopted to release the movable structure are taken into account. In this work, a high fidelity finite element model of the device was used to feed a transitional Markov chain Monte Carlo (TMCMC) algorithm for the estimation of the unknown parameters governing the aforementioned statistical features. To reduce the computational cost of the stochastic analysis, a synergy of proper orthogonal decomposition (POD) and kriging interpolation was adopted. Results are reported for a batch of nominally identical tested devices, in terms of measurement error-affected probability distributions of the overall Young’s modulus of the polysilicon film and of the overetch depth

Toolbox para plataforma de teste de MEMS

Dissertação de mestrado integrado em Engenharia Eletrónica Industrial e ComputadoresCom o crescimento do mercado de sistemas microelectromecânicos (MEMS), praticamente todos os grandes fabricantes de semicondutores têm as suas próprias linhas de produção de MEMS e enfrentam constantes aumentos de volume de produção para acompanhar a demanda destes [1]. Todos estes sistemas têm de ser testados após a produção, para caracterização das estruturas, a fim de obter as especificações da mesma, para calibração em processo fabril ou para verificação e validação do design. A oferta deste tipo de sistemas de teste é reduzida. Devido a este défice, e com o intuito de solucionar este problema, foi iniciado, na Universidade do Minho, o processo de construção de uma plataforma de teste de MEMS [2]. Atualmente, o hardware desta já foi desenvolvido, sendo agora necessário criar um conjunto de ferramentas que permitam ao utilizador interagir com a plataforma através de uma interface simples e intuitiva, garantindo uma comunicação rápida e fiável com o sistema de testes e expandindo as funcionalidades da mesma, através de blocos de software que implementem rotinas específicas de teste de MEMS. Com esta dissertação, pretende-se criar o software que solucione o problema anteriormente mencionado, passando a solução escolhida por dividir a Toolbox em três componentes principais: o driver de comunicação com a plataforma de testes utilizado para definir e converter os comandos do instrumento, a interface gráfica a desenvolver em MATLAB e as rotinas específicas de teste de MEMS. Como resultado do trabalho desenvolvido foi possível criar um sistema que permite ao utilizador interagir com a plataforma de teste de MEMS [2] de uma forma simples e intuitiva, com a fiabilidade de um driver de comunicação e expandindo as funcionalidades deste sistema, em termos de mecanismos de aquisição e teste.With the growth of the microelectromechanical systems (MEMS) market, nearly all of the main manufacturers of semiconductors have their own MEMS production lines, and have to deal with constant increases in production volumes to keep up with market demand [1]. All these systems must be tested post production, for structure characterization, in order to obtain the key parameters used, for calibration during the manufacturing process, or for design verification and validation. The offer for these types of structure characterization systems is reduced. Due to this deficit – and to solve this problem – the development process of a MEMS test platform [2] has started in the University of Minho. Currently, its hardware has already been developed, so it was necessary to create a toolbox that allows the user to easily use the platform through a simple and intuitive interface, thus allowing a fast and reliable communication with the test system and expanding its functionalities, through software blocks that implement specific MEMS test routines. This dissertation aims to create the software to solve the previously mentioned problem. With this objective in mind, the chosen solution requires that the toolbox is divided in three main components: the driver to communicate with the test platform, define and convert the instrument commands, the graphic interface designed using MATLAB and specific MEMS test routines. As a result of the creation of this toolbox, it was possible to provide the user with a simpler more intuitive way to interact with the MEMS test platform [2], adding the reliability of a driver to perform the communication and expanding the features of the system, in terms of acquisition and test modes

Digital platform for wafer-level MEMS testing and characterization using electrical response

The uniqueness of microelectromechanical system (MEMS) devices, with their multiphysics characteristics, presents some limitations to the borrowed test methods from traditional integrated circuits (IC) manufacturing. Although some improvements have been performed, this specific area still lags behind when compared to the design and manufacturing competencies developed over the last decades by the IC industry. A complete digital solution for fast testing and characterization of inertial sensors with built-in actuation mechanisms is presented in this paper, with a fast, full-wafer test as a leading ambition. The full electrical approach and flexibility of modern hardware design technologies allow a fast adaptation for other physical domains with minimum effort. The digital system encloses a processor and the tailored signal acquisition, processing, control, and actuation hardware control modules, capable of the structure position and response analysis when subjected to controlled actuation signals in real time. The hardware performance, together with the simplicity of the sequential programming on a processor, results in a flexible and powerful tool to evaluate the newest and fastest control algorithms. The system enables measurement of resonant frequency (Fr), quality factor (Q), and pull-in voltage (Vpi) within 1.5 s with repeatability better than 5 ppt (parts per thousand). A full-wafer with 420 devices under test (DUTs) has been evaluated detecting the faulty devices and providing important design specification feedback to the designers.The first author is supported by FCT-Fundacao para a Ciencia e Tecnologia through the grant SFRH/BD/91806/2012.info:eu-repo/semantics/publishedVersio