Rarefied Gas Flow Simulation based on DSMC method
About DSMC-Neutrals
DSMC-Neutrals is a 3D rarefied gas simulation software that uses the direct simulation Monte Carlo method (DSMC).
Like most CAE simulation software, DSMC-Neutrals uses an unstructured mesh, which allows for the simulation of complex geometries.
The specialty of this software is the simulation of rarefied gases to which fluid models cannot be applied due to their low pressure.
The DSMC method, based on the Monte Carlo method, to calculate the behavior of simulation particles in the computational domain with a model close to the real phenomena,
complex gas flows such as buoyancy, gravity, thermophoresis, and nanoparticle behavior in intense gas flows can be solved without the use of special physical models.
It is also possible to calculate the free molecular flow regime without considering collisions.
As well as fluid models, chemical reactions can be calculated using Arrhenius-style reaction equations. Because it can handle evaporation/desorption and adsorption of particles, it can be applied to vacuum evaporation and chemical vapor deposition. It can also be applied to simulation of pumping by a Turbo Molecular Pump (TMP) with moving structures, calculation of slider behavior on a hard disk, and calculation of narrow flow paths.
Simulations of thin-film deposition in semiconductor manufacturing such as chemical vapour deposition (CVD), vacuum deposition, organic light emitting diode (OLED) and molecular beam epitaxy (MBE) are available. We also have experience in vacuum pumping simulations to investigate conductance and pumping times. Other applications include film deposition (CIGS film) simulations for CIGS (CIS) solar cells, which have recently attracted attention, and gas flow analysis for plasma-based equipment such as arc ion plating (AIP). As for high pressure calculations, we have experience in calculating the behaviour of hard disk sliders.
Package
| Software | Modules | Features |
|---|---|---|
| DSMC-Neutrals | Neutral gas solver |
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| Pre-processor |
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| Post-processor |
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| Parallel |
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Examples
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CIGS and CIS films are used as solar panel films.
CIGS and CIS films are usually deposited under low pressure conditions,
for which the Monte Carlo direct method (DSMC) is very effective.
OLEDs have been used for displays and lighting.
OLEDs are often deposited under low pressure conditions.
Usually, the pressure in the evaporation cell of organic materials is relatively high and the deposition distribution cannot be reproduced by solving as a free molecular flow.
This is why the DSMC method is very effective.
MBE is a vacuum deposition method for crystal growth under low pressure conditions.
The high vacuum in the chamber makes it difficult to solve using a fluid model,
and the DSMC method is one of the most effective simulation methods.
DSMC-Neutrals can take into account reaction data in Arrhenius format, thus enabling calculations of chemical deposition taking into account chemical reactions.
DSMC-Neutrals uses an unstructured mesh, which makes it possible to calculate complex geometries.
This makes it possible to simulate, for example, the conductance of piping connected to a turbomolecular pump.
DSMC-Neutrals can simultaneously consider drachmatic forces (resistive forces), thermophoresis and gravity.
This makes it possible to calculate dust behaviour and simulate the effects of dust on contamination.
Thermophoresis is also used to protect against contamination of fine particles from lithography masks.
DSMC-Neutrals can calculate thermophoresis, which is difficult to analyse using fluid models or free molecular flow analysis software.
The distance between the hard disk media and the head at the tip of the slider has become very narrow, several [nm].
The DSMC-Neutlrals can obtain calculation results in a short time even for such a high pressure calculation model due to the narrow calculation area.
The gas pressure in AIP equipment is very low. Therefore, the gas flow can be calculated by DSMC-Neutrals.
Gas flows around hypersonic objects, such as satellites entering the atmosphere, can be calculated.
In rarefied gases, such as in chambers, shocks are likely to occur near the nozzle. Convection occurs in areas between objects with temperature differences, as temperature cannot be transferred by thermoconduction alone. |
OLED 1 (click to enlarge) 
OLED 2 (click to enlarge) 
Showerhead CVD 1 (click to enlarge) 
Showerhead CVD 2 (click to enlarge) 
Dust behaviour 1 (click to enlarge) 
Dust behaviour 2 (click to enlarge) 
Hard disk head (click to enlarge) 
Hypersonic rarefied flow (click to enlarge) 
Shock waves (click to enlarge) 
Benard convection (click to enlarge) |
Papers
In the following papers DSMC-Neutrals is used.