Interconnect scaling-the real limiter to high performance ULSI

Reducing interconnect pitch improves layout density, but degrades interconnect RC delay. Increasing metal aspect ratio (thickness/width) improves RC delay, but maximum benefits are achieved at an aspect ratio of ~2. Adding more interconnect layers improves density and performance, but practical limits are reached in just a few generations. New conductor and dielectric materials and improved circuit design techniques will be needed to meet future ULSI interconnect requirements