Ab Initio Modelling of Chemical Vapor and Area‐Selective Atomic Layer Deposition - Developing an Automated Exploration of Surface Reaction Networks
In the present dissertation the surface reactivity of small molecules within the thin film growth by chemical vapor deposition and area-selective atomic layer deposition is studied by density functional theory. In a first part, an approach for an automated exploration of reaction networks is prese...
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|In the present dissertation the surface reactivity of small molecules within the thin film growth by chemical vapor deposition and area-selective atomic layer deposition is studied by density functional theory.
In a first part, an approach for an automated exploration of reaction networks is presented with PESE. PESE obtains adsorption minima by a grid‐based sampling of the surface of interest. In addition, by extending the grid layer in the z‐direction the adsorption basin of every minima is derived. Here, the volume of the adsorption basins is interpreted as the geometric probability of the adsorbate to adsorb in a certain minimum. Based on all unique adsorption minima, possible decomposition structures are proposed. The decomposition structures are obtained by following implemented rules exploiting the connectivity graphs of the studied molecule. Based on the obtained adsorption and decomposition minima, diffusion and decomposition paths are proposed by PESE. An initial guess for every reaction path is generated by combining a linear interpolation in cartesian coordinates for the surface model with a linear interpolation in internal coordinates for the adsorbate, while for the optimization of the reaction path a tailored and improved version of the NEB method is used. The first part of this thesis is completed by studying with bismuth, gallane and phosphine on gallium phosphide several systems of interest.
In a second part of this thesis, the usage of different classes of molecules as small molecule inhibitors for the area-selective atomic layer deposition of high‐κ dielectrics such as aluminium oxide and hafnium oxide is investigated. Here, the adsorption and reactivity of five alkoxysilane based small molecule inhibitors, methanesulfonic acid and diethyl sulfide are studied. With the alkoxysilane based small molecule inhibitors the question regarding the optimal number of reactive and blocking groups is addressed, while with methanesulfonic acid and diethyl sulfide the effect of surface dependent reaction mechanisms is shown. Overall, computational methods are successfully applied to identify the surface reaction mechanisms and understand the experimentally observed blocking behaviors. The hereby gained knowledge will promote the development of novel inhibitors and the fine‐tuning of the area-selective atomic layer deposition process.