Large‐Area Uniform 1‐nm‐Level Amorphous Carbon Layers from 3D Conformal Polymer Brushes. A “Next‐Generation” Cu Diffusion Barrier?

Abstract

A reliable method for preparing a conformal amorphous carbon (a‐C) layer with a thickness of 1‐nm‐level, is tested as a possible Cu diffusion barrier layer for next‐generation ultrahigh‐density semiconductor device miniaturization. A polystyrene brush of uniform thickness is grafted onto 4‐inch SiO2/Si wafer substrates with “self‐limiting” chemistry favoring such a uniform layer. UV crosslinking and subsequent carbonization transforms this polymer film into an ultrathin a‐C layer without pinholes or hillocks. The uniform coating of nonplanar regions or surfaces is also possible. The Cu diffusion “blocking ability” is evaluated by time‐dependent dielectric breakdown (TDDB) tests using a metal−oxide−semiconductor (MOS) capacitor structure. A 0.82 nm‐thick a‐C barrier gives TDDB lifetimes 3.3× longer than that obtained using the conventional 1.0 nm‐thick TaNx diffusion barrier. In addition, this exceptionally uniform ultrathin polymer and a‐C film layers hold promise for selective ion permeable membranes, electrically and thermally insulating films in electronics, slits of angstrom‐scale thickness, and, when appropriately functionalized, as a robust ultrathin coating with many other potential applications.

2D (< 10 nm) sp3-C-rich carbon materials, possibly hydrogenated: A review

“…In this method, a polystyrene brush of uniform thickness which was grafted onto SiO 2 /Si substrate was transformed into ultrathin amorphous carbon layer without pinholes or hillocks by UV crosslinking and subsequent carbonization. However, as revealed by XPS C1s and Raman spectra, and by surface roughness analysis, the films produced are sp 2 -C-rich rather than sp 3 -C-rich [58] .…”

“…An alternative is a use of a synthesis method that does not use any ion bombardment during the film formation. Recently a new method for preparing a conformal amorphous carbon layer with a thickness of 1 nm was shown [58] . In this method, a polystyrene brush of uniform thickness which was grafted onto SiO 2 /Si substrate was transformed into ultrathin amorphous carbon layer without pinholes or hillocks by UV crosslinking and subsequent carbonization.…”

Unlocking More Potentials in Two-Dimensional Space: Disorder Engineering in Two-Dimensional Amorphous Carbon

“…The impermeable barrier layer is one of the critical structures in modern electronics: for example, in metal interconnect stacks. In order to effectively avoid undesired permeation of specific atoms or molecules, the barrier layer needs to be highly homogeneous, thermally and chemically stable, strongly adherent, and capable of being grown/placed on the complex surface of devices in a simple way . Graphene was considered one promising candidate for the ultrathin diffusion barrier layer due to its excellent electrical properties and stability .…”

Fabrication of High-κ Dielectric Metal Oxide Films on Topographically Patterned Substrates: Polymer Brush-Mediated Depositions

“…A significant advantage of the polymer brush technique over SAM depositions is the fast processing speed (a few minutes for polymer brush grafting vs hours to days for SAM’s monolayer coating). Furthermore, the polymer brush-assisted deposition process overcomes the issues that the ALD technique poses such as the line of sight deposition and the possibility of uniformly coating trench corners or sidewalls . So far, the polymer brush technique has been shown to facilitate the deposition of metal oxide films uniformly across relatively smooth substrate surfaces.…”

“…Furthermore, the polymer brush-assisted deposition process overcomes the issues that the ALD technique poses such as the line of sight deposition and the possibility of uniformly coating trench corners or sidewalls. 27 So far, the polymer brush technique has been shown to facilitate the deposition of metal oxide films uniformly across relatively smooth substrate surfaces. The application of this technique throughout the trenches and pitches of a topographically patterned substrate would dramatically widen the use case scenarios and allow additional device integration and provide advantages over current methodologies.…”