A Numerical Simulation of Motion of Particles under the Wafer in CMP

Motion of particles in two-phase flow between two rotary pads is simulated with coupled lattice Boltzmann method (LBM) and discrete element method (DEM), in which the LBM is used for calculating the fluid flow, while the DEM for accounting for the interaction between the moving particles, both the particles and the pads are constructed by the 'boundary' in LBM. Numerically, flow field on the down-pad is simulated, two vortexes are found; Pressure maps are observed with different pad angle velocities; Finally motion of particles are investigated, our results show that most of the particles between the pads get out of the interlayer at nearly the same place, and the trajectory is like a parabola at the left hand side of the up-pad, all of them demonstrate the capability of the presented coupling strategy.

1 Introduction

FLow with small particles between two rotary pads can be found in many scientific and engineering applications, such as chemical mechanical polishing(CMP) in tribology, air mechanics, environment engineering, in these cases, the particles path and distribution are very important, however, it is very difficult to observe the particles path on-line. In this paper, motion simulation of particles in twophase flow between two rotary pads is numerically simulated with coupled lattice Boltzmann method (LBM) and discrete element method (DEM), in which the lattice Boltzmann method is employed to model the fluid flow while discrete element method to account for the particle/particle interaction.