13.8 The ELSA Simulator

The ELSA (Enhanced Level Set Applications) simulator is a general tool for topography simulation in the realm of semiconductor manufacturing processes. It consists of four modules, namely a level set module (cf. Section 13) based on the algorithm in Section 13.6, a surface reaction module, and a module for particle transport by radiosity or diffusion. It can be used for simulating all common deposition and etching processes.

Among its features are the following. The initial surface is given by an arbitrary number of points. The grid is a homogeneous rectangular one and the coarsening algorithm from Section 13.7 can be applied recursively an arbitrary number of times and with a given maximum deviation angle. The sophisticated level set algorithm from Section 13.6 provides the basis for surface tracking. Both the first and second order space convex schemes (cf. Section 13.5) are implemented.

The simulator is written in Common Lisp and uses foreign function calls to some of the FORTRAN77 routines available in the LAPACK library [32] for calculating the flows at the wafer surface. The grids and internal arrays can be written to output files in MATHEMATICA syntax and the simulation results are visualized by code written in MATHEMATICA. Finally the simulator can easily be adapted to new simulation problems by user defined functions. All the simulations in Chapter 12 were performed using ELSA.