STRESS MEASUREMENTS IN SILICON DEVICES THROUGH RAMAN-SPECTROSCOPY - BRIDGING THE GAP BETWEEN THEORY AND EXPERIMENT

The different steps that have to be taken in order to derive informati on about local mechanical stress in silicon using micro-Raman spectros copy experiments, including theoretical and experimental aspects, are discussed. It is shown that the calculations are in general less compl icated when they are done in the axes system of the sample. For that p urpose, the secular equation is calculated in the axes system [110], [ -110], [001], which is important for microelectronics structures. The theory relating Raman mode shift with stress tensor components is appl ied using two analytical stress models: uniaxial stress and planar str ess. The results of these models are fitted to data from micro-Raman s pectroscopy experiments on Si3N4/poly-Si lines on silicon substrate. I n this fit procedure, the dimensions of the laser spot and its penetra tion depth in the substrate are also taken into account. (C) 1996 Amer ican Institute of Physics.