Efficient and innovative use of three-dimensional geometry services in IC topography and process flow simulations

This paper describes the development of and experimentation with Berkeley Topography Utilities (BTU), a 41000-line object-oriented (C++) system integrating geometry services from Berkeley´s topography simulators and the IBM Geometry Engine. The BTU interface hierarchically organizes topography data into primitive, auxiliary, and aggregate views for flexible combinations of geometry and numerical methods, acts as a testbed for performance testing of geometry servers, and provides application development utilities for rapid development of new simulation applications. Using aggregate utilities for deformation and visibility, new etching and deposition simulators can be written in about 350 lines of code. Auxiliary views such as monotone surfaces are shown to be Important for efficiently accessing CPU-intensive services such as merge, deloop, and visibility. For three-dimensional surfaces with about 1000 triangles, monotone decomposition can be used to reduce CPU-intensive service calls by one to two orders of magnitude. Through the BTU interface, a new capability is created to tag process history on wafer features by combining process flow simulation with solid model attribute propagation. The usefulness of this capability is demonstrated on trace-back of topography propagation effects