MEMS Fabrication Process

As discussed in the Introduction, MEMS is an iterative process, repeating the same steps time and time again until the final design is achieved, as in the graphic that illustrates this basic process. You start with a silicon wafer and apply a photosensitive coating to it that is called photoresist. When you expose your coated wafer to UV light, the regions blocked by your glass mask (containing your pattern for that layer) are not exposed. Thus, those regions are not resistant to the chemicals and will be washed away when rinsed. Then, when you expose your wafer to wet or dry etching, these same regions are vulnerable to the etching process and get etched away. The depth and shape of the etching is dependent on the process used, the amount of time, and the crystal orientation of the wafer. When completed, the wafer is rinsed in a different solution, such as acetone, and the final result (for that layer) can be seen.