Molecular Dynamics Simulations of Atomic Layer Deposition Processes

Abstract

The nature of the atomic layer deposition is the molecular engineering. The process optimization and de novo precursor-apparatus design require detailed understanding of precursor and substrate interactions at the atomic level. It would be ideal to monitor the precursor delivery influx and reactions at the substrate surface as a function of process control variables. It is also useful to analyze the molecular organization at each stage of the deposition process cycles. A promising theoretical approach to monitor such nano-scale molecular constructs is the molecular dynamics simulation. We utilize the well-established molecular simulation program package, CHARMM (Chemistry at HARvard Molecular Mechanics) to carry out molecular manipulations and to integrate the equations of motion. The molecular mechanical model is developed for the OH/H terminated Si(100) surface, precursors and chemical intermediates in the deposition process. The surface reactions are modeled as the molecular rearrangement. ZrO2 deposition process is simulated for the Zr(NEt2)4 / H2O alternating reactant influx system. 2 -Si-OH + Zr(NEt2)4 → {- Si - O- }2 Zr(NEt2)2 + 2HNEt2 { -Si - O- }2 Zr(NEt2)2 + 2H2O → { -Si - O- }2 Zr(OH)2 + 2HNEt2 A deposition cycle is composed of the metal organic precursor influx, purge outflux, H2O influx, and purge outflux. As of this writing, we have performed 30 deposition cycles on the 80% OH-terminated Si(100) surface. Simulations with 50% and 100% OH-terminated substrates and extended simulations for more deposition cycles are in progress.