Copper interconnect barrier layer structure and formation method

Abstract

A method for forming a tungsten-containing copper interconnect barrier layer (e.g., a tungsten [W] or tungsten-nitride [W N] copper interconnect barrier layer) on a substrate with a high (e.g., greater than 30%) sidewall step coverage and ample adhesion to underlying dielectric layers. The method includes first depositing a thin titanium-nitride (TiN) or tantalum nitride (TaN) nucleation layer on the substrate, followed by the formation of a tungsten-containing copper interconnect barrier layer (e.g., a W or W N copper interconnect barrier layer) overlying the substrate. The tungsten-containing copper interconnect barrier layer can, for example, be formed using a Chemical Vapor Deposition (CVD) technique that employs a fluorine-free tungsten-containing gas (e.g., tungsten hexacarbonyl [W(CO) ]) or a WF -based Atomic Layer Deposition (ALD) technique. The presence of a thin TiN (or TaN) nucleation layer facilitates the formation of a tungsten-containing copper interconnect barrier layer with a sidewall step coverage of greater than 30% and ample adhesion to dielectric layers. A copper interconnect barrier layer structure includes a thin titanium-nitride (TiN) (or tantalum nitride [TaN]) nucleation layer disposed directly on the dielectric substrate (e.g., a single or dual-damascene copper interconnect dielectric substrate). The copper interconnect barrier layer structure also includes a tungsten-containing copper interconnect barrier layer (e.g., a W or W N copper interconnect barrier layer) formed on the thin TiN (or TaN) nucleation layer using, for example, a CVD technique that employs a fluorine-free tungsten-containing gas (e.g., [W(CO) ]) or a WF -based ALD technique.