Resist process, lithography

X-ray lithography also takes advantage of the increased resist sensitivity due to the thinner imaging films of multilayer systems. Thinner imaging films further improve X-ray resolution by minimizing the penumbra effect, a problem associated with an uncollimated X-ray beam. Consequently, the oblique exposure of features near pattern edges are minimized by multilevel resist processes, thereby restoring the desired profile. 

The evolution of resist materials and resist processes over time has closely paralleled the evolution of lithography. Generally, the evolution of resists can be divided into two main eras, namely, the dichromate era and the modern era (see Fig. 6.1). There have been many important discoveries in resist materials and processes, some of the most significant of which are covered in this chapter and the next. 

Professor C. Grant Willson of The University of Texas at Austin introduced me to lithography and supervised my doctoral thesis. I learned the intricacies of resist processing under the tutelage of the late Dr. Jeffrey Byers of SEMATECH. 

We wrap up the discussion of this phase of resist processing by mentioning that for x-ray and ion beam lithography, energy deposition models have been developed to simulate PMMA resist systems (35-37). 

You are to optimize the thickness of resist used in a production lithographic process. There are a number of competing effects in lithography. 

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