Nanoscale elastic imaging: a new metrology tool for low-k dielectric integration

A new characterization tool based on ultrasonic force microscopy (UFM) has been developed to image the nanoscale mechanical properties of metal/low-k polymer damascence test structures. Metal and polymer regions are differentiated on the basis of elastic modulus with a spatial resolution less than or equal to 10 nm. This technique reveals a RIE-induced hardening of the low-k polymer at the metal/polymer interface and offers new opportunities for metrological reliability evaluation of low-k integration processes