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Critical Length and Resistance Saturation Effects in Al(Cu) Interconnects
Published online by Cambridge University Press: 10 February 2011
Abstract
A new test structure for electromigration failure analysis of via-interconnect metallization schemes was developed. Multi-via/interconnect chain arrays were used in a parallel/serial testing arrangement. Due to improved statistical sampling, the multi-via test structures enabled measurement of drift velocity phenomena at via/interconnect interfaces with a very limited number of test devices per stressing condition, and without reducing the signal to noise ratio. Furthermore, realistic, production-type metallization schemes can be characterized without usually required “traditional” drift velocity-type metal stacks incorporating highly resistive shunt-layers. Critical length effects were investigated as a function of line length and current density. At interconnect lengths close to the critical Blech-length, resistance saturation effects were encountered and used for calculations of the critical current density-length product, (jl)*. Furthermore, a new resistance saturation model was developed and found to correlate well with the acquired data. Critical length effects can accurately be measured and used for length-dependent interconnect performance evaluation on the device-level.
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- Copyright © Materials Research Society 1998
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