Indirect Nanofabrication

The essence of nanofabrication is to make nanoscale structures by which lithography is the key to define a pattern. Previous chapters have described that each lithographic method has its own capability and limit. However, there are also ways to get around of these limits. This chapter is to introduce those methods or tricks to make high resolution pattern structures without using highly expensive tools. The so-called indirect implies that these methods are not direction patterning by lithography such as optical or e-beam exposure of polymer resists, but combination of different fabrication techniques, particularly through etching (dimensional subtraction) and deposition (dimensional addition). The width of a pattern structure is defined by the thickness of deposited sidewall, so is the name of sidewall lithography. Even if a direct lithography is used, the traditional limit in resolution can be overcome by utilizing the feature of energy distribution in combination with exposure threshold of resists, which is the concept of super-resolution patterning. Different from other published books on the topic of nanofabrication, this book is the only book that groups those clever tricks together under the heading of indirect nanofabrication.