Unconventional Processing And Characterization Methods In Lithography
As lithography moves toward feature sizes of 22 nm and smaller and pushing for applications beyond the semiconductor industry, unconventional processing and characterization methods are in demand for patterning of unusual structures, new processing techniques, and better understanding and control of resist performance. Chapter 1 introduces conventional lithographic processing and characterization methods and their unconventional counterparts as well. As a typical lithographic process includes exposure, post-exposure bake, and development, chapters 2, 3 and the appendix cover some unconventional processing methods. Chapter 2 discusses a laser heating method for exposed chemically amplified photoresists in an attempt to control acid diffusion during postexposure bake and thus improve pattern resolution and quality. Chapter 3 details supercritical carbon dioxide as an environmentally friendly and sustainable solvent to develop high resolution resist patterns. Two photon lithography is demonstrated in the appendix as a direct write technique to introduce three dimensional defects inside photonic materials. While conventional characterization of the materials and/or patterns is usually carried out before and after the lithographic process, an in situ FTIR method is discussed in chapter 4 as a technique to monitor reaction-diffusion kinetics of acids in chemically amplified molecular glass resists during post-exposure bake and to understand the molecular architectural effect on the kinetics.
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