New methods of probing beyond the limits of optical penetration have been developed using sensitive laser modulated reflectance techniques. Coupled with this subsurface defect detection method is a new surface topography imaging method. Together, these techniques nondestructively produce submicron-resolution images of surface and subsurface inhomogeneities in microelectronic structures. The measurables of these techniques are related to current reliability subjects. In interconnect metalization processes, defects such as stress- and electromigration-induced voids, precipitates of silicon or copper, sidewall notches, and hillocks and pits are images with these techniques. Sequential stressand-probe nondestructive testing allows the growth rate and other dynamical processes to be documerited. In silicon substrates, metal contamination and crystallographic defects are detected. In this talk, the measurement techniques are described and examples of their usage for VLSI reliability improvement are related.