Published online by Cambridge University Press: 01 February 2011
Dry etching of Cu challenges the Focused Ion Beam (FIB) removal of metallizations. Cu metallizations are comprised of numerous, randomly orientated crystallites. Each orientation shows a different etch rate under ion bombardment, leading to unacceptable damage to underlying dielectric. An improved methodology for uniform Cu etching over dielectric consists of three steps: 1) Exposure, 2) Initial off-normal bombardment and 3) Chemistry assisted ion bombardment. Comparison is made with and without preliminary off-normal bombardment. It is shown that Cu etching preceded by off-normal bombardment was completed ∼50% sooner with decreased dielectric over-etch.