Software for Modeling Low Pressure Gas Flow in Vacuum Systems

In an ion implanter, the average number density of outgassing molecules along the beam path is used as a figure of merit to evaluate the design. It must be computed as a function of wafer angle, with rotation about one axis.

Accurate Modeling of Low Pressure, Low Velocity Gas Flows

The Molecular Flow Module is designed to offer previously unavailable simulation capabilities for the accurate modeling of low pressure, low velocity gas flows in complex geometries. It is ideal for the simulation of vacuum systems including those used in semiconductor processing, particle accelerators and mass spectrometers. Small channel applications (e.g. shale gas exploration and flow in nanoporous materials) can also be addressed.

The Molecular Flow Module uses a fast angular coefficient method to simulate steady-state free molecular flows. You can model isothermal and nonisothermal molecular flows, and automatically calculate the heat flux contribution from the gas molecules. The discrete velocity method is also included in the module for the simulation of transitional flows.

Two Methods for Modeling Free Molecular and Transitional Flows

The Molecular Flow Module offers two alternatives to these methods, allowing you to solve for low velocity and low pressure flows in a manageable and accurate fashion. Two specific physics interfaces, configured to receive model inputs via the graphical user interface (GUI) to fully specify a set of equations, are available:

Molecular Flow in an Ion Implant Vacuum System

Adsorption and Desorption of Water in a Load Lock Vacuum System

Differential Pumping

Molecular Flow Through a Microcapillary

Rotating Plate in a Unidirectional Molecular Flow

Outgassing Pipes

Molecular Flow in an RF Coupler