Biomedical engineering research today is focused on non-invasive techniques for detection of biomarkers related to specific health issues 1. Three metal layer microelectrode (μE) sensors have been implemented to detect specific biomarkers which can be found in human saliva related with heart failure problems 2 such as interleukin and Tumore Necrosis Factor-α (TNF-α), and used as highly sensitive saliva sensors. We designed specialized μEs combining different technologies for multiple measurements aiming to a lab-on-a-chip future integration. Measurements are based to basic principles of Cyclic Voltammetry (CV) and Electrochemical Impedance Spectroscopy (EIS). Thus, certain planar technology was used involving three metal layers of gold, platinum and silver deposited over an oxidized silicon substrate following standard cleanroom procedures of lithography for the definition of μEs, sputtering physical vapor deposition (PVD) for gold, evaporation PVD for silver and platinum, and plasma enhanced chemical vapor deposition (PECVD) for passivation layer of silicon nitride.
A fast and flexible fabrication method that allows the creation of silicon structures of various geometries is presented. It is based on the combination of focused ion beam local gallium implantation, selective silicon etching, and diffusive boron doping. The structures obtained by this resistless method are electrically conductive. Freely suspended mechanical resonators of different dimensions and geometries have been fabricated and measured. The resulting devices present a good electrical conductivity which allows the characterization of their high-frequency mechanical response by electrical read-out.
Design verification methodologies and tool such as DRC and ERC used on MEMS design have been inherited from the transistor based analog and digital full custom design flows. However the devices are defined on a 2D layout, they have a 3D structure. Thus, current tools do not have into account the new features that appear in MEMS design, especially those related with device micro machining. The main consequence on it is that it is necessary to include information of the vertical parameters on the DRC, what is not at all usual in classical design. We claim that the inclusion of such information together with the consequent improvement of tools for DRC, ERC and device parameter extraction, can reduce design and simulation efforts as well as improve the manufacturing yield.
In this work the development of a design and manufacturing methodology for application-specific integrated sensor systems in silicon, that extends the ASIC standard cell approach for circuits, is presented. The standard design environment of a commercial foundry is used. A library of micromachined sensors and specific interface circuit cells has been added to the foundry's libraries. A fabrication structure has been set up in which the CMOS foundry process is followed by a micromachining post-processing transparent to the user. This includes back-side membrane fabrication. A number of standard sensor cell types have been developed: ISFET chemical sensors, gas flow and infrared radiation sensors based on thermopiles and piezoresistive pressure sensors. Mass-beam structures suitable for accelerometer devices have also been fabricated.
We propose a design and technology methodology and CAD tools for a microsystems fabrication based on the 1.0 micrometers CMOS from ATMEL-ES2. In order to profit from vendor cell libraries, design kits have to be enhanced to deal with the new conception environment. Main contributions are, sensor dependent technology file, device modeling and automatic generation for different ranges, and adaptation of semi- custom tools (simulation environment and P and R) for complete microsystems design. A library of dedicated sensor cells is being designed using Cadence DFWII and the foundry design kit. These sensors are fabricated with the standard CMOS process plus some post-processing steps. Three levels of post-processing are considered: 1) pH-ISFET sensors fabricated using standard CMOS, 2) gas flow and radiation sensors based on thermopiles using simple post-processing. The post-processing is compatible with the foundry CMOS process. Our technology has been developed up tot he point of maximum simplification that results in the use of only one additional mask for back-side etching. Passivation layer together with oxide windows are used for front-side etching with excellent results.
Conference Committee Involvement (8)
Smart Sensors, Actuators, and MEMS VIII
8 May 2017 | Barcelona, Spain
Smart Sensors, Actuators, and MEMS VII
4 May 2015 | Barcelona, Spain
Smart Sensors, Actuators, and MEMS VI
24 April 2013 | Grenoble, France
Smart Sensors, Actuators and MEMS
18 April 2011 | Prague, Czech Republic
Smart Sensors, Actuators and MEMS
4 May 2009 | Dresden, Germany
Smart Sensors, Actuators and MEMS
2 May 2007 | Maspalomas, Gran Canaria, Spain
Smart Sensors, Actuators, and MEMS II
9 May 2005 | Sevilla, Spain
Smart Sensors, Actuators, and MEMS
19 May 2003 | Maspalomas, Gran Canaria, Canary Islands, Spain
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