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3.1.1 Defining a Simulation Domain

In contrast to manufacturing, where for obvious reasons only entire wafers are processed, it is necessary to define an area of interest for the simulation. This might range from single structures like vias or trenches of shallow trench isolation (STI) features to transistors or other single active or passive devices up to a larger area including several devices with their interconnects. The choice of the simulation domain depends on the problem under investigation and is related with the required accuracy tunable by the number of cells used per unit length.

Figure 3.1: Definition of a simulation domain.

Defining a simulation domain as depicted in Fig. 3.1 is like starting with a bare wafer in the fabrication facility. The solid modeling program allows the definition of the extensions of the three-dimensional simulation domain and defines the cell resolution. Furthermore it specifies the vertical position of the wafer surface within the simulation domain. For etching processes the surface will be located close to the top of the simulation domain, for deposition steps it will reside lower in the simulation domain in order to avoid, that the applied structures exceed the upper limit of the simulation domain.

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