Photothermoacoustic and photoelectric microscopy of silicon

Abstract

Combined photothermoacoustic and photoelectric microscopy is used to investigate silicon-based structures: an epitaxially grown n-type region in a p-type substrate, a p-p + interface obtained by implanting boron ions, and a region near a crack tip. It is concluded that the visualization of epitaxial regions by thermal waves most probably stems from the elastic stresses appearing during fabrication of the structures. It is shown that the spatial distribution of the elastic stresses appearing upon ion implantation is visualized by thermal waves. In the region near the crack tip inhomogeneities in the thermoelastic and energy properties extending over hundreds of microns can be diagnosed by thermal waves and electron-hole plasma waves. Spatial periodicity with a period ∼85 µm is discovered in the variation of the thermoelastic properties near the crack tip.