Barrier integrity testing of Ta using triangular voltage sweep and a novel CV-BTS test structure

Abstract

Numerous techniques are available for evaluating the efficacy of barrier materials at preventing the diffusion of copper into dielectric materials. In this study, the capability of triangular voltage sweep (TVS) as a means of determining barrier integrity is investigated. Also in the study, a new test structure is introduced for performing capacitance voltage bias temperature stress (CV-BTS) tests. This test structure, which is designed to mimic barrier performance at the bottom of vias where step coverage is a challenge, was used to determine the diffusion barrier properties of PVD deposited tantalum as a function of Ta thickness in 0.25-μm vias.