by Pawan Fangaria
MEMS design and fabrication is highly complex in the sense that the fabrication process heavily depends on the design, unlike IC fabrication which has a standard set of processes. A slight change in MEMS design can alter its fabrication steps to a large extent. For example, setting device parameters such as capacitance or linear displacement can affect the choice of the film thickness, etch rate, sidewall profile and so on. The design and process are so much tied together that many iterations through the fab are required (which consume costly resources and time) in order to get a perfect build. While an IDM has to keep its fab resources deployed for such a build-and-test experimentation in-house, a fabless design house has to additionally incur time for its design to take several tours through an external fab. This all has significant impact, first on cost of design and manufacturing and then turn-around-time, thus squeezing the window of opportunity which is already small in today’s competitive semiconductor market.
In such a scenario, there is nothing like having a software tool at the designer’s desk which can provide a 3D model of the complete MEMS device based on its layout and process description. The iterations between the design and the process can take place virtually at the terminal itself until the final model of the device is perfect to enter the fab for manufacturing.