Photolithographic patterning applications

The high selectivity of wet etchants for different materials, e.g. Al, Si, SiOz and Si3N4, is indispensable in semiconductor manufacturing today. The combination of photolithographic patterning and anisotropic as well as isotropic etching of silicon led to a multitude of applications in the fabrication of microelectromechanical systems (MEMS). 

Methods are now available to make small and well-defined enzyme membranes on FET surfaces. The performance of these enzymatically coupled FETs with a photolithographically patterned enzyme membrane as well as their practical applications are described. It is reasonable to conclude that the enzymatically coupled FET s have reached a stage of development where they can be applied to real-world problems. 

Fig. 2 Comparison of the resolution (w) and PS depth (d) resulting from photolithographic patterning of PS. (a) Chronologieal referenee list (b) reported resolution/depth overlaid on loosely assigned applicable fields along with a comparative 1 1 isotropie eteh line dashed line)...

This type of coil was prepared from copper cladded printed circuit board material by applying photolithographic techniques. The p.c. board material is available with difierent copper thicknesses and with either a stiff or a flexible carrier. The flexible material offers the opportunity to adapt the planar coil to a curved three dimensional test object. In our turbine blade application this is a major advantage. The thickness of the copper layer was chosen to be 17 pm The period of the coil was 100 pm The coils were patterned by wet etching, A major advantage of this approach is the parallel processing with narrow tolerances, resulting in many identical Eddy current probes. An example of such a probe is shown in fig. 10. 

Abstract A crucial problem in the manufacturing of high aspect ratio structures in the microchip production is the collapse of photoresist patterns caused by imbalanced capillary forces. A new concept to reduce the pattern collapse bases on the reduction of the capillary forces by adsorption of a cationic surfactant. The application of a cationic surfactant rinse step in the photolithographic process leads to a reduction of the pattern collapse. Physicochemical investigations elucidate the mechanism of surfactant adsorption... 

The enzymatically coupled FET is reviewed in this chapter (32). First, a brief review is given. Determining how to deposit an enzyme-immobilized membrane on the surface of a FET was one of the most difficult problems to solve before tin enzymatically coupled FET could be developed. Therefore, some enzyme-immobilized membrane deposition methods and the photolithographic enzyme-immobilized membrcme patterning method developed by the authors are described in detail. Concomitantly, the performances of some FET biosensors with an enzyme-immobilized membrane made by this method are described. Finally, recent applications of an enzymatically coupled FET are surveyed. 

Polyamic acid methacrylate esters are the first self-patternable, pure organic polyimide precursors to be described. They are the polymer basis of the first technically applied resist to produce polyimide patterns in a direct process. They are synthesized simply by the addition of hydroxyethylmethacrylate to aromatic acid dianhydride, and subsequent polycondensation of the intermediate tetracarboxylic acid diester with aromatic diamines. These polyimide precursors give rise to a number of special photoresist properties which lead to important applications, such as photolithographically produced protection layer against a-radiation on memory... 

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