TABLE OF CONTENTS So far, this chapter has considered a range of elements found in microsystems, and grouped these into passive, sensing and actuating components. It was also shown how different materials can be produced on a substrate and a methodology for selecting materials appropriately for a given application was discussed. The process by which these microsystem elements can be fabricated from the basic materials is considered next.
The process by which structures are manufactured from a material is known as micromachining. This is further subdivided into surface micro-machining in which only the surface layers of material are acted upon, resulting in devices which are no more than a few tens of micrometres deep, and bulk micromachining in which large quantities of the substrate material, perhaps hundreds of micrometres in depth, are removed.
Light sensitive polymers, called photoresists, are normally employed for initially creating a pattern on the surface of a sample to be micromachined, and the process by which this is achieved is discussed before the principal micromachining technologies etching, bonding and planarisation are described.
Having produced a series of material layers that are to be converted into a structure, it is necessary to be able to actually produce a pattern in the material layers. Photolithography is the most common means of achieving this at the micrometre length scale by coating the surface of the material to be patterned in a light sensitive polymer. The...
