Atomic Layer Deposition of Pt on Surface Deactivated by Fluorocarbon Implantation: Investigation of Growth Mechanism

Abstract

Selective atomic layer deposition (ALD) using surface-controlled reactivity is attracting a great deal of attention as a simple bottom-up patterning process that can provide both continued dimensional scaling and accurate pattern placement for next-generation nanoelectronics. We previously reported topographically selective deposition through Pt ALD using a MeCpPtMe3 precursor and an O2 counter reactant on fluorocarbon (CFx)-modified surfaces; however, gradual loss of selectivity in the CFxmodified regions was observed during the Pt ALD process. This work develops a fundamental understanding of the microscopic growth mechanisms of Pt ALD on the CFx-modified surface using a combination of experimental analyses and theoretical methods. The Pt growth characteristics on the CFx surface are investigated within a temperature window from 225 to 350 °C, and the results show a sharp sensitivity to growth temperature, with significant Pt growth occurring at temperatures above 300 °C. Through density functional theory (DFT) calculations, the reaction energies for adsorption of oxygen and the MeCpPtMe3 precursor as well as formation of reaction products of CFx degradation are determined. Based on experimental results in conjunction with the DFT calculations, we show that while lower temperature Pt ALD (<300 °C) on CFx-modified surfaces can be significantly retarded because of a lack of MeCpPtMe3 chemisorption, the surface reaction pathways for Pt ALD on CFx-modified surfaces at temperatures above 300 °C can proceed through oxygen adsorption and CF4 desorption followed by Pt nucleation in CFx-degraded regions. © 2020 American Chemical Society