Method of forming a self aligned copper capping layer

Abstract

A method of forming a capping layer on a copper interconnect line (14). The method comprises providing a layer (20) of Aluminium over the interconnect line (14) and the dielectric layer (10) in which it is embedded. This may be achieved by deposition or chemical exposure. The structure is then subjected to a process, such as annealing or further chemical exposure, in an environment containing, for example, Nitrogen atoms, so as to cause indiffusion of Al into the copper line (14) and nitridation to form a diffusion barrier 26 of the intermetallic compound CuAlN.

Description

technical field [0001] The present invention relates to a method for forming a self-aligned copper capping layer associated with a copper interconnect layer of a semiconductor device in order to improve its reliability and to improve capacitive coupling between lines. Background technique [0002] In the past, aluminum was the predominant conductive material used in electrical interconnects in semiconductor devices due to its low resistivity, good adhesion to silicon dioxide, low price, ease of bonding, and good etchability . As device geometries continue to scale down for very large scale integration, there is an increasing need for interconnect routing with fine spacing and high conductivity while requiring higher levels of reliability. Currently, an integrated circuit is considered to be performing well if testing shows an equivalent useful life of 10 years. However, in some specific applications, such as space applications (e.g., satellites, probes, etc.), medical (e.g...

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Problems solved by technology

Also, the creation of the protective layer requires the diffusion of aluminum, and inward diffusion may occur equally across the entire interconnect line

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