Buried irregular interfaces and particulate present special challenges in terms of chemical analysis and identification, and yet are critically important to diagnose in the manufacture of electronic materials and devices. Cross-sectioning at the right location is often difficult, and, while dual-beam SEM/FIB instruments can often provide excellent visualization of buried defects, matching chemical analysis may be absent or problematic. ToF-SIMS depth profiling, with its ability to acquire spatially-resolved depth profiles while collecting an entire mass spectrum at every "voxel", offers a way to re-visit the problem of buried defects. Unlike traditional dynamic SIMS applications, the emphasis will be on the qualitative, not the quantitative. Multivariate analysis of the overwhelming amount of data can reduce the output from essentially a depth profile at every mass to a small set of chemically-meaningful factors. Examples of ToF-SIMS depth profiles of relatively homogeneous layers, severely inhomogeneous layers, and buried particulate will be discussed.