(183r) Optimal Design of Novel Precursor Materials for Atomic Layer Deposition Using Computer Aided Molecular Design

Atomic Layer Deposition (ALD) is a promising technique in which deposition of thin films takes place on a substrate through sequential and self-limiting surface reactions. A precursor used in this process chemisorbs on the substrate and part of the molecule subsequently desorbs from the surface after completion of the reaction. Precursor chemisorption on the substrate leads to a self-limiting process and it eventually results in films with desired thickness at Ångström length scale. In order to design an ALD experiment, one should decide on precursor(s) based on the ALD conditions (i.e., bubbler and reactor temperatures, pressure, gas flow, etc.) and likely applications of the final film. It is practically impossible to carry out a huge number of ALD experiments using numerous precursors and deposition conditions in order to find the optimum one depending on the applications of interest. Moreover, only existing precursors can be tested with experiments. The objective of this work is to develop a novel computational tool which leads us to design novel precursor materials for the ALD of metal oxides and metals.

Group Contribution Method (GCM) is a technique to predict thermodynamic properties of a compound from the structural and functional groups comprising the molecule. Computer Aided Molecular Design (CAMD) is the reverse of GCM where the functional groups are combined to generate materials having optimal desired properties. For CAMD, we need properties of the functional groups. In our previous work, we have redeveloped a new GCM for ALD to predict the growth rate curve using Adsorbate Solid Solution Theory (ASST) ¹. In this work, properties of the functional groups will be used to generate novel precursor molecules. Since this results in combinatorial explosion of alternatives, we will be using a combinatorial optimization method called Efficient ant colony optimization (EACO) for this problem. This is the first time CAMD is being applied to design precursor materials for ALD. The designed precursors will then be tested experimentally for ALD and characterization of the deposited films will validate the proposed simulation technique.

References:

1. Shahmohammadi M, Mukherjee R, Takoudis C, Diwekar M. A Group Contribution Method for Optimal Design of Novel Precursors for the Atomic Layer Deposition, Submitted to AIChE Journal (2019)