Editing Surface micromachining (section)

== Layers ==
Generally, [[polysilicon]] is used as one of the substrate layers while [[silicon dioxide]] is used as a ''sacrificial layer.'' The sacrificial layer is removed or etched out to create any necessary void in the thickness direction. Added layers tend to vary in size from 2-5 micrometres. The main advantage of this machining process is the ability to build electronic and mechanical components (functions) on the same substrate. Surface micro-machined components are smaller compared to their bulk micro-machined counterparts.

As the structures are built on top of the substrate and not inside it, the substrate's properties are not as important as in bulk micro-machining. Expensive [[Silicon Wafer|silicon wafers]] can be replaced by cheaper substrates, such as [[glass]] or [[plastic]]. The size of the substrates may be larger than a silicon wafer, and surface micro-machining is used to produce [[thin-film transistor]]s on large area glass substrates for flat panel displays. This technology can also be used for the manufacture of [[thin film solar cell]]s, which can be deposited on glass, [[Polyethylene terephthalate|polyethylene terepthalate]] substrates or other non-rigid materials.