2.5.5 Generic Services

The orthogonality of the PIF syntax greatly facilitates future extensions (without syntax changes), but introduces some semantical ambiguities. The PIF itself, be it its ASCII or binary form, only defines a general syntax for expressing physical situations. Ambiguities generally arise from the multitude of possible descriptions of the same physical problem in terms of PIF syntax. Most of these ambiguities are, however, inevitably induced by physical modeling and are not specific to PIF. In order to unambiguously interpret PIF data, there are additional semantic constraints which applications have to adhere to (at the cost of some PIF flexibility). A set of (mainly semantical) constraints is implied by the wafer state conventions. A few examples are:

• A geometry consists of multiple, not necessarily connected segments. For each segment, a standard materialtype must be defined.
• A segment consists of positively oriented, singly-connected faces or solids.
• A standard wafer coordinate system is used for the points of the geometry.
• For each geometrical segment there must be at most one grid defined, which must conform to the boundaries of the segment.
• Doping information is specified using ImpurityDescription attributes which must reference the grid.
• An exposed boundary construct marks the lines or faces of the geometry which is part of the wafer surface. All other boundaries are artificial.

There are sometimes severe semantical data conflicts and gaps to fill between simulators (for example, a simulator working on an unstructured, triangular grid being coupled with a simulator using a tensor product grid) which are dealt with in a high level toolkit (Figure 2.7), comprised of generic PIF-based applications such as grid generators, interpolators, and attribute and geometry manipulators. One such generic framework tool, VORONOI, is also subject of the present work and is described in detail in Chapter 6.

Visualization is another technology-independent service that can be provided by the framework. The underlying architecture and the implementation of some interesting modules is described in Chapter 5.