Stress measurements in sub-μm Si structures using Raman spectroscopy

As the minimal structure size in silicon devices keeps shrinking, mechanical stress is becoming more and more important. The method of Raman spectroscopy allows to measure stress in Si locally resolved and nondestructively. We use Raman spectroscopy to follow the evolution of stress in Si devices after different processing steps, gaining information about its origin and relative magnitude. We show that it is possible to obtain information on stress changes from structures as small as 0.25 mu m, and that therefore the minimal structure size needed to obtain useful information is much smaller than the laser spot size of approximate to 1 mu m.