Simulation of Semiconductor Lithography and Topography

Fundamental physical mechanisms in deposition and etching generate both desired and undesired topographic features. The goal of this chapter is to provide a basic foundation for understanding and modeling their effects on topography profile time-evolution. A common framework for modeling etching and deposition is given along with the terminology used to describe various physical phenomena and effects. Sweeping the profile with a domain of influence for a point source can be used to model the time-advance. Alternatively facets in a representation of a surface can be advanced using a vector sum of advancement rates normal to the facet. In many cases the processes themselves produce planar facets and analytical solutions are given for several simple cases. Several phenomena in ion milling including lateral shifts and corner faceting are described. A more rigorous methodology for analyzing the generation an annihilation of slow-advancing and fastadvancing facets is described using results developed by F.C. Frank and C.H. Sequin for crystal etching based on slowness surfaces. Examples of simulation of several basic deposition and etching processes conclude the chapter.