Question

What are different fabrication techniques for MEM devices? What are their problems? How can they be rectified?

Answer 1

Micro-Electro-Mechanical Systems, or MEMS, is a technology that in its most general form can be defined as miniaturized mechanical and electro-mechanical elements that are made using the techniques of microfabrication.

In MEMS devices, a three-dimensional spatial structure is formed on the substrate and mechanical blocks are formed within that structure. A system is then created by fabricating electrical circuits that drive those mechanical blocks on the same substrate. This technology is targeted at devices that range in size from mm down to microns, and involve precision mechanical components that can be manufactured using semiconductor manufacturing technologies. These devices can replace bulky sensors and actuators with micron-scale equivalents. This reduces cost, bulk, weight and power consumption while increasing performance, production volume and functionality.

In the most general form, MEMS consist of mechanical microstructures, microsensors, microactuators and microelectronics, all integrated onto the same silicon chip. This is shown schematically in the figure.

MicroActuators MEMS Microstructures MicroSensors Microelectronics

This vision of MEMS whereby microsensors, microactuators and microelectronics and other technologies,are integrated onto a single microchip is expected to be one of the most important technological breakthroughs of the future. This will enable the development of smart products by augmenting the computational ability of microelectronics with the perception and control capabilities of microsensors and microactuators. Microelectronic integrated circuits can be thought of as the "brains" of a system and MEMS augments this decision-making capability with "eyes" and "arms", to allow microsystems to sense and control the environment. Sensors gather information from the environment through measuring mechanical, thermal, biological, chemical, optical, and magnetic phenomena. The electronics then process the information derived from the sensors and through some decision making capability direct the actuators to respond by moving, positioning, regulating, pumping, and filtering, thereby controlling the environment for some desired outcome or purpose. Furthermore, because MEMS devices are manufactured using batch fabrication techniques, similar to ICs, unprecedented levels of functionality, reliability, and sophistication can be placed on a small silicon chip at a relatively low cost. MEMS technology is extremely diverse and fertile, both in its expected application areas, as well as in how the devices are designed and manufactured. Already, MEMS is revolutionizing many product categories by enabling complete systems-on-a-chip to be realized.