Dependence of stress and resistivity of sputtered copper films on deposition conditions

Abstract

Stress and resistivity in sputtered copper films on glass and polyimide (Kapton H) substrates were studied as functions of deposition rate and argon working gas pressure. For deposition rates from 1 A/sec to 5 A/sec, three regions were studied at different argon gas pressures : (1) a compressive region at 2 mTorr, (2) a tensile region at 10 mTorr and (3) an intermediate region at 3.5 mTorr with a deposition rate of 4.8 A/sec corresponding to the transition from the tensile to the compressive region. Our results and discussions suggest that the morphology and impurity level are important factors in determining the resistivity and stress in the film. We found that either an increase in the deposition rate or a decrease in the working gas pressure result in a more continuous film with lower resistivity (or higher conductivity). A crude stress generation model and an impurity model were used to explain most of the resistivity and stress behavior observed

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