TOP-DOWN NANOTECHNOLOGY SOFT LITHOGRAPHY

Within the last decade, comparatively inexpensive and scaleable tchniques known as soft lithography have been the focus of much development. Patterning of a substrate is afforded by using a master elastomeric stamp that contains a nanostructured pattern, known as a relief on its surface. Contrary to photolithography, the resolution of the final pattern is not limited by light diffraction, but only depends on the 

In order to improve the stamping resolution of the elasomeric stamp, there have been recent improvements in both the stamp and molecular inks e.g., alkylthiols, silanes). In particular, traditional PDMS exhibits a relatively high elasticity that limits possible relief linewidths on the other hand, small molecular weight inks exhibit diffusion during patterning. Hence, the following complementary strategies have been employed  

Using a combination of the above modifications has now extended nanocontact printing to well below the 30nm regime - even as low as 

A general benefit of DPN over other soft lithographic techniques is the ability to pattern nanostructures (including biological materials) by a single step without crosscontamination, since the desired chemistry occurs only in a specifically defined location of the substrate. 

The mechanism of ink transport from the AFM tip to substrate is currently an item of controversy. Recent models suggest that a meniscus forms between the tip 

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