Models and algorithms for three-dimensional topography simulation with SAMPLE-3D

Abstract

Algorithms for general surface advancement, three-dimensional visibility, and convolution over a surface have been developed and coupled with physical models for pattern transfer. The resulting program, SAMPLE-3D, allows practical simulation of plasma etching and deposition processes on engineering workstations. The physical models are 3-D extensions of 2-D string and segment based models. The models include secondary effects, such as material density variations and damage enhanced etching. A general facet motion algorithm supports simple, isotropic, cosine-directional, and general surface orientation dependent processes. A 3-D grid of rectangular prismatic cells, which is updated by the advancing surface, contains an alternate topography representation for fast shadow and visibility calculation. The program is organized as a collection of modular functions for continued model and algorithm development. Guidelines for estimating CPU and memory requirements for various models and simulation cases are based on an analysis of the algorithms and data structures. Simple processes, such as lithography development, require 1-5 min of CPU time. Simulations involving integration over flux distributions, such as plasma etching and sputter deposition, require from 5-30 min for typical cases. Reflection or surface migration calculations require from 30-60 min. Physical memory of 4-32 megabytes is sufficient for many practical simulations. >