Nondestructive probe of microstructures covered with a micrometer-thick insulating layer

Abstract

We present an imaging technique which uses a scanning photoelectron microscope to image microstructures covered with a micrometer-thick insulating layer at submicrometer depth and lateral-space resolution. Line shifting in the photoelectron spectrum caused by local charging in the insulating surface layer provides depth information. This technique was used to nondestructively image micropatterns in a semiconductor device down to 3 μm beneath a surface insulating layer. The depth resolution was 0.2 μm, and the lateral-space resolution was 0.5 μm.