The manufacturing processes related to the Micro Electro Mechanical Systems (MEMS) and microelectronics fields are based on 2D or planar technologies. This implies the construction of components or products is on or in flat wafers.

MEMS products take their starting point in a prepared wafer (usually silicon) cleaned and oxidised. Then, they are formed by creating patterns in the various layers of the wafer. Pattern transfer consists of a photographical transfer of the desired pattern to a photosensitive film covering the wafer, followed by a chemical or physical process to remove or add material in order to create the pattern [9]. This basic flow of MEMS micromachining is depicted in Fig. 2.18.

Photo-lithography is the basic technique used in pattern transferring between many others like X-ray lithography, charged particle beam lithography, extreme ultra violet lithography, etc. Besides these, the potential of the emerging lithography methods is noticeable, e.g. stereo-lithography, in which the possibility to build truly 3D microstructures is present (see Fig. 2.19a).

Most usual chemical or physical processes mentioned above are listed in Table 2.5.

2.18 Basic flow of MEMS micromachining.

The microfabrication by MEMS processes is currently accomplished by three major technologies, namely, bulk micromachining, surface micromachining and micromolding (LIGA). These techniques group different processes mentioned before.

Previous /  Next