Plasma surface micromachining

Oxygen plasma cleaning. The integrated surface-micromachined wafer is exposed to an oxygen plasma to remove the photoresist and thus create free 3D structures as shown in Figure 5.2.9. 

Unlike bulk micromachining, where the substrate silicon is the machining element, surface micromachining utilizes deposited films, such as polysilicon, silicon nitride, and nickel. In surface micromachining plasma settings are an... 

To create micromachines, films that have been deposited must be patterned and etched to reveal the desired structures. Often, it is important to etch these structures with vertical sidewalls (anisotropic etching). In this case, most pattern transfer operations (lithography and etch) are carried out using plasma etching. Conceptually, this process is the reverse of deposition. The etching process consists of exposure of the patterned and masked substrate to a low-pressure plasma. The reactive species and ions preferentially etch those areas that are not masked, resulting in the definition of features on the surface. The key to plasma etching is that the products of the reaction of the activated gas and the material to be etched must be volatile (see e.g.. Ref ). 

Determination of the temperature distribution induced by laser, electron, or plasma beam sources is relevant in operations such as surface transformation hardening of metals, drilling, cutting, annealing, shaping, and micromachining. Descriptions of beam-generating devices as well as discussions of applications are available [7-15]. 

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