Microfabrication processes soft lithography

Popular microfabrication methods include lithographic, galvanoformung, abformtechnik (LIGA), wet and dry etching processes, micromachining, lamination, and soft lithography. An overview of these techniques is given here and specifics can be found in the references. 

Also referred as soft lithography because they rely on the use of an elastomer, usually poly(dimethylsiloxane)(PDMS), these types of processes consist in the replication of patterns either identical or complementary to those of a master. Soft lithography allows to achieve conformal and high resolution (nm scale) patterning with flat or curval substrates and enables the use of materials incompatible with optical lithography or other conventional microfabrication techniques. Different replication techniques are possible such as... 

Microfabrication is a process used to generate physical devices onto substrates. These devices are formed by structures with dimensions from millimeter to nanometer range. Figure 3.1 shows a piece of silicon (Si) wafer with devices after the completion of the fabrication. Over the years, microfabrication has advanced significantly from the established semiconductor fabrication processes used for integrated circuits (ICs) to diverse materials and processes such as polymers, liquids, soft lithography, and liquid-based processes. 

In addition to the three basic microfabrication steps discussed above, other fabrication techniques are quite useful. We will briefly discuss a few of them, namely lift-off, annealing, liquid phase photopolymerization, micromolding, soft lithography, electroplating, sacrificial processes, bonding, surface modification, laser-assisted processes, planarization, and fabrication on flexible substrates and curved surfaces. Some of these techniques do not necessarily belong to the traditional repertoire of microfabrication of ICs. However, they have proved very useful for the creation of other types of microdevices and systems such as MEMS, microfluidics, and labs on chips. 

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