Atomic Layer Deposition of Ruthenium Thin Films from (Ethylbenzyl) (1-Ethyl-1,4-cyclohexadienyl) Ru: Process Characteristics, Surface Chemistry, and Film Properties

Grillo

Marques

et al. 2018

Self Cite

consisting of two or more alternating self-limiting surface reactions. These selflimiting surface reactions enable thin-film deposition with thickness uniformity over large-area substrates, (sub-) monolayer thickness control, and conformal deposition in 3D structures. [1] During the first ALD cycles the precursors mainly react with the substrate rather than with the ALD-grown material. The surface termination of the substrate can therefore strongly affect the growth behavior during this initial period. [1][2][3] Depending on the nature of the ALD-grown material, the substrate, and the process conditions, ALD can lead to different growth regimes, resulting, for instance, in the deposition of ultrathin continuous films, deposition of highly dispersed nanoparticles, or area-selective deposition. [4] Continuous thin films have a wide variety of applications including nanoelectronics, coatings, and optical components, and their deposition requires either 2D growth or high particle density to achieve fast film closure. Nanoparticles dispersed on a surface are desired for heterogeneous catalysis, and their production requires island-type deposition with a well-defined particle size and particle density. Area-selective deposition can enable nanoscale bottom-up patterning, which allows accurate self-alignment between small features which is difficult to achieve in conventional top-down patterning. [5] To enable area-selective deposition, the growth behavior should be surface-dependent such that the deposition is at the same time favored on designated areas of the substrate and inhibited on others. For each of the aforementioned applications, an understanding of the surface dependence of the initial stages of growth can inform the tailoring of the ALD process to the desired application. [6] ALD of noble metals has received considerable attention because of its potential in applications such as catalysis [7] and nanoelectronic devices. [8] Ruthenium is considered an ideal candidate for novel nanoscale catalysts [9,10] as well as for replacing copper as a conductor in future low-level nano-interconnect structures for integrated circuits. [8] ALD of Ru however presents application-specific challenges. On one hand, nanoparticles of a specific size are desired for high catalytic activity. [10] On Understanding the growth mechanisms during the early stages of atomic layer deposition (ALD) is of interest for several applications including thin film deposition, catalysis, and area-selective deposition. The surface dependence and growth mechanism of (ethylbenzyl)(1-ethyl-1,4-cyclohexadienyl) ruthenium and O 2 ALD at 325 °C on HfO 2 , Al 2 O 3 , OH, and SiOSi terminated SiO 2 , and organosilicate glass (OSG) are investigated. The experimental results show that precursor adsorption is strongly affected by the surface termination of the dielectric, and proceeds most rapidly on OH terminated dielectrics, followed by SiOSi and finally SiCH 3 terminated dielectrics. The initial stages of growth are characterized by the formation a...

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Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

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Section: Introductionmentioning

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Diffusion‐Mediated Growth and Size‐Dependent Nanoparticle Reactivity during Ruthenium Atomic Layer Deposition on Dielectric Substrates

Grillo

Marques

et al. 2018

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Defect Mitigation in Area‐Selective Atomic Layer Deposition of Ruthenium on Titanium Nitride/Dielectric Nanopatterns

Hody

Spampinato

et al. 2019

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Area-Selective Deposition (ASD) receives increasing attention as a bottom-up approach for nanoelectronic device fabrication. Uptake of ASD is however limited by defects, which manifest as undesired particle growth on the non-growth surface. We demonstrate a defect mitigation solution for Ru ASD on TiN/SiO2 nanopatterns by making use of the size-dependent Ru nanoparticle reactivity. During the initial stages of 1-(ethylbenzyl)-1,4-(ethylcyclohexadienyl)ruthenium and oxygen (EBECHRu/O2) Atomic Layer Deposition on dielectrics, Ru particles are too small to catalytically dissociate oxygen, and their growth is suppressed. This phenomenon creates an ASD process window in which particles can be completely etched while retaining the integrity of the ASD pattern on a TiN growth surface. Decreasing the ALD temperature strongly suppressed defect growth, which can be used to expand the process window for ASD. The ASD process window is confirmed by Self-Focusing Secondary Ion Mass Spectrometry (SF-SIMS) with its low limit of detection while analyzing 10 4 structures simultaneously. No defects are detected for Ru ASD on 36nm TiN/SiO2 patterns by SF-SIMS. We apply the Ru ASD process for bottom-up block patterning and obtain functional hardmask patterns on 300mm wafers. The approach followed in this work can produce defect-free ASD processes for a wide variety of applications.

Selectivity Enhancement for Ruthenium Atomic Layer Deposition in Sub‐50 nm Nanopatterns by Diffusion and Size‐Dependent Reactivity

Clerix

Marques

et al. 2021

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Area‐selective deposition (ASD) is a promising bottom‐up approach for fabricating nanoelectronic devices. However, a challenge is to prevent the undesired growth of nanoparticles in the nongrowth area. This work uses kinetic Monte Carlo (KMC) methods to investigate the defectivity in ruthenium ASD by (ethylbenzyl)(1‐ethyl‐1,4‐cyclohexadienyl)Ru/O2 (EBECHRu) atomic layer deposition (ALD) in line‐space nanopatterns with different dimensions. Ru ASD is governed by adsorption as well as diffusion. The defectivity depends on the pattern dimensions, as nanoparticles can diffuse and reach the interface with the growth area where they aggregate. For linewidths of 50 nm and smaller, all Ru adspecies are captured at the growth interface before growth by precursor adsorption is catalyzed. The synergetic effect of diffusion and size‐dependent reactivity reduces defectivity below 1010 Ru atoms cm−2 for at least 1000 ALD cycles. This is more than 1000 times lower than for patterns with a linewidth of 200 nm and larger, where the Ru content decreases significantly only near the interface with the growth surface. The predicted depletion zone is confirmed by experiments in nanoscale line‐space patterns. Overall, this mechanism results in smaller and fewer Ru nanoparticles for smaller patterns, facilitating the development of passivation‐deposition‐etch ASD processes for nanoelectronic device fabrication.