Abstract :
The microfabrication technology has had a chequered history of over 50 years in the field of microelectronics. Aggressive miniaturization of microelectronic devices has resulted in faster logic circuits; & and it has also reduced their power requirements. MOSFET device dimensions have already entered the sub-100 nanometer regime. The same successful principles of microfabrication were applied to make miniaturized 3-dimensional mechanical structures. This helped in the advent of micro electro-mechanical systems or MEMS. Initially, i.e. in early nineties, the MEMS field was dominated by mechanical applications. However, now MEMS refers to all miniaturized systems including silicon based mechanical drivers, chemical and biological sensors and actuators, and miniature devices made from plastics or ceramics. The half-day tutorial would begin with a synoptic overview of the area of Nanotechnology & then shift towards MEMS. It will highlight some of the challenges and outline the scope of the tutorial. Next we discuss about why is it that they are becoming so popular; for eg the advantages they offer: orders of magnitude smaller size, better performance than other solutions, possibilities for batch fabrication, cost-effective integration with electronics, virtually zero dc power consumption, potentially large reduction in power consumption, etc. Next, we discuss some of the popular MEMS applications & some of the emerging MEMS applications: The application domains cover micro sensors and actuators for physical quantities of which MEMS for automobile & consumer electronics forms a large segment; and microfabricated systems for chemical assay (microTAS) and for biochemical and biomedical assay (bioMEMS and DNA chips). This tutorial would give an introduction to these exciting developments and the technology and design approaches for the realization of these integrated systems. We will also introduce the importance of material selection by understanding t- e impact of material properties at the micron scale. We will discuss polymeric materials such as SU-8 and also compare them with traditional materials such as Silicon. We will also discuss about the possibility of integrating MEMS with VLSI electronics. Unit processes for bulk and surface micromachining of silicon and integration of processes for fabricating silicon microsensors will be presented. Simulators provide an excellent way to design, optimize and understand micromechanical systems. Particularly so because such systems are not of isolated, stand-alone type; instead, they are based on the interplay of several domains. For example, in a microcantilever based biosensing system the different domains are: materials, mechanical, biological, electrical and chemical. Recently developed software packages such as Coventorware, Intellisuite etc. have the ability to simulate a system in different domains. We will discuss basic philosophy of using MEMS simulation tools for simple devices. While MEMS represents a diverse family of designs; devices with simple cantilever configurations & microheater configurations are especially attractive as transducers for chemical and biological sensors. We will review several important aspects of these transducers - namely: (i) operation principles; (ii) fabrication; and (iii) applications. We will discuss about our work in the area of healthcare applications to make a MEMS based instrument that can help physicians in diagnosing a heart attack event. We will also present our work to develop a MEMS based explosives detector. Finally, we discuss about the instruments (Omnicant & Sensimer), that we have developed to help researchers experiment with microcantilevers & microheaters.
