In general simple three-dimensional geometry editors only provide operations on a very low physical level and can only be controlled interactively. If automation and an appropriate level of accuracy is required, integrated topography simulation is needed to supply the desired structures.
Since three-dimensional simulations in general make high demands on system resources, the most important requirements for three-dimensional topography simulation and geometry generation are accurate modeling within acceptable limits of memory consumption and efficient algorithms for remaining within reasonable CPU times. In most cases simulations can be performed satisfactorily with simple and fast models for most of the process steps and only the critical processes have to be calculated more accurately. Topography programs preferably should be able to cover the whole range of simulations between the two limiting cases of highly accurate single process step optimization and fast integrated geometry generation for large structures.
In recent years a variety of three-dimensional topography simulators based on different algorithms such as level set techniques [1]-[4], facet motion [5]-[7] or Monte-Carlo methods [8][9] has been introduced. Most of them are specialized in single process simulation and do not provide facilities for direct inclusion of layout information from standard layout data file formats.
In this paper we present optimized structuring element algorithms for cellular topography simulation which in combination with layout inclusion and solid modeling tools are well suited for three-dimensional, physically motivated geometry generation for device simulation and interconnect studies. By these means we close the gap between accurate modeling of lithography, resist development and topography simulation available for single feature simulation, e.g., [10] and layout based geometry modeling.
Before going into the details of the new developments, Section 2 discusses the scope of this article and gives a preliminary discussion on timing, accuracy, and integration aspects. Section 3 describes the fundamentals and the initial implementation of our surface movement algorithm followed by the optimizations carried out for isotropic etching/deposition (Section 3.1), unidirectional etching/deposition (Section 3.1), and sputter deposition (Section 3.3). Furthermore we explain how we include layout information into the topography simulation (Section 4) and show the application of the presented algorithms to the simulation of interconnect structures.
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