Numerical simulation of a single wafer atomic layer deposition process

Abstract

Atomic Layer Deposition (ALD) is a process used to deposit nanometer scale films for use in nano electronics. A typical experimental reactor consist of a warm wall horizontal flow tube, a single disc mounted halfway down the tube, and an alternating cycle flow between a reactant gas and a wash in a carrier gas. The process is governed by the desire to achieve a uniform coating on the substrate layer. Optimization is currently accomplished by monitoring the precursor delivery and the growth of the film and adjusting flow rates accordingly. Maslar et al (2008) showed that it is possible to use in situ monitoring of the gas phase for optimization. With the data provided from that work, it is now possible to verify a numerical model of the flow process. The process can be thought of in 5 parts: unsteady undeveloped pipe flow, mixing, flow around a disc, flow impinging on a disc, boundary layer reactions on a wall. In this thesis, I numerically simulated the unsteady undeveloped pipe flow, mixing and boundary layer reactions on the wall. I also describe but do not solve a model for the complete process and propose criteria for optimization.