Surface Diffusion Control Enables Tailored Aspect Ratio Nanostructures in Area-Selective Atomic Layer Deposition

TL;DR

This paper demonstrates how controlling surface diffusion during area-selective atomic layer deposition enables the creation of nanostructures with tailored aspect ratios, improving process precision in microelectronics.

Contribution

It reveals the role of surface diffusion control in tailoring nanostructure aspect ratios and identifies reaction mechanisms affecting selectivity, advancing deposition process strategies.

Findings

Surface modifications manipulate surface diffusion to control nanostructure growth.

Kinetic Monte-Carlo simulations show species move from high to low diffusion areas.

Process optimization improves selectivity by managing catalytic activity.

Abstract

Area-selective atomic layer deposition is a key technology for modern microelectronics as it eliminates alignment errors inherent to conventional approaches by enabling material deposition only in specific areas. Typically, the selectivity originates from surface modifications of the substrate that allow or block precursor adsorption. The control of the deposition process currently remains a major challenge as the selectivity of the no-growth areas is lost quickly. Here, we show that surface modifications of the substrate strongly manipulate the surface diffusion. The selective deposition of TiO$_2$ on poly (methyl methacrylate) and SiO$_2$ yields localized nanostructures with tailored aspect ratios. Controlling the surface diffusion allows to tune such nanostructures as it boosts the growth rate at the interface of the growth and no-growth areas. Kinetic Monte-Carlo calculations reveal that species move from high to low diffusion areas. Further, we identify the catalytic activity of TiCl$_4$ during the formation of carboxylic acid on poly (methyl methacrylate) as the reaction mechanism responsible for the loss of selectivity, and show that process optimization leads to higher selectivity. Our work enables the precise control of area-selective atomic layer deposition on the nanoscale, and offers new strategies in area-selective deposition processes by exploiting surface diffusion effects.