Paper PS-ThM11
Feature Profile Simulator with Atomic Mono-Layer Resolution Capability
Thursday, October 31, 2013, 11:20 am, Room 104 C
Theoretical and experimental understanding of plasma interactions with solid materials has led to development of 2D and 3D feature profile simulators. Different approaches have been used for over 40 past years for that. Our simulator, FPS3D [1-2], is a general code which uses a cellular model for representing solid materials and uses Monte Carlo pseudo-particles for representing all incoming fluxes of reactive species. Those particles are launched such that statistically they represent the angle-energy distribution of fluxes coming to the wafer from the plasma. Each particle typically contains many molecules, but preferentially significantly less than the number of molecules in a full cell. FPS3D is very different in many ways from other feature profile simulators, most importantly in the way how it represents gaseous and solid materials and how it represents interactions of reactive gaseous species with solids. The algorithms applied enable simulation of very large span of models ranging from large features of hundreds of microns to very small ones of a few nanometers where a cell size is approaching to the size of a single molecule. Regimes with application of beams, plasmas, or just reactive gases could be conveniently simulated. Interaction with solids is described very differently for low-energy and high-energy particles. While the low-energy gaseous species interact only with the surface layers of the cells, the energetic particles such as ions or fast neutrals could penetrate into the body of the cells, and could even go through the cells. The finite penetration depth of a fast particle into a solid material is a key factor dictating the regime of interaction. When an energetic particle moves through a cell, it loses energy there on collisions and bond breaking between atoms. The energetic particle finally stops and implants in a solid material. The deposited energy might be enough for some molecules to diffuse to other cells or go through upper layers. This way, etching through polymer layers could be simulated. Correspondingly, FPS3D can simulate etching, deposition, and implantation processes going on at the same time. Also among new developments to be presented is the capability of considering multi-step (or multi-recipe) processes, when each step could have different fluxes to the surface and different chemistry. Another new development in FPS3D is a possibility of simulating pulsed-plasma effects. Examples are mainly based on a case of HARC etching of SiO2 by the fluorocarbon-argon-oxygen plasma.[1] P. Moroz, ECS Transactions, 35 (20) 25 (2011).
[2] P. Moroz, IEEE Transactions of Plasma Science, 39 (11) 2804 (2011).