LAUSR

A reliable method for preparing a conformal amorphous carbon (a-C) layer with a thickness of 1-nm-level, was tested as a possible Cu diffusion barrier layer for next-generation ultrahigh density semiconductor device miniaturization. A polystyrene brush of uniform thickness was grafted onto 4-inch SiO2 /Si wafer substrates with "self-limiting" chemistry favoring such a uniform layer. UV crosslinking and subsequent carbonization transformed 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" was evaluated by time-dependent dielectric breakdown (TDDB) tests using a metal-oxide-semiconductor (MOS) capacitor structure. A 0.82 nm-thick a-C barrier gave 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. This article is protected by copyright. All rights reserved.