Surface and tomographic distribution of carbon impurities in photonic-grade silicon using laser-induced breakdown spectrometry

Abstract

Laser-induced breakdown spectrometry (LIBS) has been tested as a method for surface analysis of photonic-grade silicon. A pulsed nitrogen laser (337.1 nm) was used to create a microplasma on the silicon, the light from which was dispersed and detected by a charge-coupled device (CCD) detector. A total area of 3×2.1 mm² was analysed with a lateral resolution of 70 µm and depth resolution of about 0.16 µm. Factors affecting lateral and depth resolution of the approach were studied. Two- and three-dimensional distribution maps of carbon contamination on silicon are presented. Mapping by LIBS seems to be a powerful tool to use for the 3D characterisation of solid samples combining in a single step, surface and subsurface analysis capabilities.