A new test structure for electromigration failure analysis of via-interconnect metallization schemes was develped. 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. Due to improved statistical sampling, the molti-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 acan be chanracterized without usually required "traditional" drift velocity-type metal stacks incorporating highly resistive shunt-layers. Critucal 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.
展开▼
