PPRLabs Expertise

Plasma simulations in process chambers

Plasma simulations as a part of integrated modeling for plasma process modification and chamber design optimization in semiconductor industry:
  • General analysis of plasma behavior in remote / direct plasma processing chambers for semiconductor industry including biased / pulsed / magnetron / dual frequency rf plasma sources
  • Numerical analysis of unstable behavior of rf discharges in process chambers such as ionization instability, local overheating instability and plasma localization due to undesired gas breakdown in order to avoid negative effect of plasma treatment on the material properties
  • Development of non-equilibrium plasma chemistry in complex mixtures of molecular gases (BCl3, N2, O2, H2, HBr, Cl2, C2F6, NH3, NF3, SiF4, SiH4, SiCl4, C2H2, CH4), models of charged and neutral species interaction with materials surface
  • Development of kinetic models to predict deposition, dry etching, thin film densification rates and profiles in combination with quantum chemistry and Monte Carlo simulation. Modeling of thin film formation or modification due to chemical reactions of incoming flows with solid or film. Surface reactions, diffusion and reactions in the film (solid) as well as sputtering and implantation can be taken into account in the model
  • Mote Carlo calculations of energy and angle distributions of ions and fast atoms bombarding the wafer in combination with plasma modeling for the arbitrary chamber geometry

Monte Carlo ray tracing and view factor analysis

Monte Carlo ray tracing problems:
  • Various lamp arrays + reflectors shape optimization tasks. Better uniformity or higher/lower radiative heat flux was needed in heating of the substrate or other chamber components. Different reflector or lamp arrays geometry was the input and parts irradiance profiles were the output. VBA scripts for automatic geometry change and simulation run were used.
  • Sputter deposition processes. In assumption of no collisions inside the volume (Kn > 10) ray tracing represented real deposition process. Surface emissivity values were used as sticking coefficients for deposition reactions.
  • View factor matrix calculation for complex (100+ 3D objects) systems of 3D components for further use in network thermal models. Automatization of runs was mandatory for such tasks.
  • Pyro radiation leakage. Task was to understand the lamp radiation fraction that reaches the pyro and causes error in surface temperature measurements. Laser energy leakage to outer parts of the chamber. Some fraction of laser energy escaped the chamber domain and reached outer parts. Minimization of this fraction was needed.

CFD, Reacting Flow

CFD simulations have been performed in the direction to predict neutrals transport from plasma source through the different process volumes separated by showerheads:
  • Recombination of cleaning gases with thermal effects of gas species recombination on manifolds and solid parts. 3D showerhead to 2D axisymmetric geometry assumption has been developed. Technique to model nozzles of a 3D showerhead as 2D circular slots has been applied. 2D and 3D modeling with multiple showerheads and flow path from plasma source to outlet pumping liner
  • Simulation of macroparticles flow, dust and spray droplets in variety of chambers in order to predict contamination and scratches in purging chambers
  • Parameterization of complex models: Developed Python scripts and Fortran subroutines to parametrize simulation models. Instead of redoing geometry and mesh preparation by user, script/subroutine does it automatically for specified input parameters (Ansys Fluent, CFD-Ace+, Python, Fortran).

Quantum Chemistry Modelling

Quantum chemistry simulations aim to explore the mechanisms of chemical reactions in plasma processing such as etching, deposition, and the recombination of radicals:
  • Highly selective method of plasma etching which would preferentially etch silicon nitride (Si3N4) over silicon oxide (SiO2). This kind of etching is one of the most challenging steps during 3D-NAND flash memory fabrication
  • Studying of mechanism of precursor formation of BNNT (boron nitride nanotube) growth during high temperature synthesis
  • Plasma processing of III-V materials such as GaN and AlGaN using BCl3 gas
  • Selective deposition of metals on low-K and metal surfaces
  • Recombination of O, H and F atoms on aluminum oxyfluoride surfaces