SEM Monte Carlo Model

This feature produces simulation of both backscattered and secondary electrons and is compatible with inverse scattering code. It also measures simulated SEM line scans and produces animated ray tracing simulated SEM data. Extensive Materials Properties Databases and a database for atomic scattering parameters are included. The simulation has been checked with NIST Monte Carlo code, MONSEL, under SEMATECH contract.

Scanning Electron Models

The SEM models use Monte Carlo methods. The primary electron enters the material and experiences a series of elastic scatterings while continuously slowing down due to electromagnetic interactions between the electron and the solid. Backscattered electrons are collected by a split anular detector, with an inner and outer angular range as well as a user definable energy range. The secondary model is phenomenological in that it presumes a secondary generation coefficient for each material proportional to secondary generation whenever the primary electron is within a skin depth of an exterior surface. The user first specifies the SEM geometry and materials using the SEM geometry editor. Then he defines the detector geometry as well as beam energy and scan parameters. Two run modes are available. One gives a graphical animation of the scanning and Monte Carlo scattering, whereas the other is a background batch mode which runs much faster since it doesn't have to draw the images of the Monte Carlo trajectories.

The SEM model is useful for simulating linewidth measurement.