Determination of Residual Stresses in Microsystems Using X-Ray Diffraction

Due to the individual steps of manufacturing various kinds of residual stresses and strains are induced in devices and components of microsystems. Often these residual stress states differ considerably from those determined in well known conventional materials and materials compounds. This is caused by the small dimensions of the single components and by the great variety of materials combinations used. X-ray diffraction is a powerful tool also for the investigation of the residual stress states in microsystems, because it enables the non-destructive testing of materials and components and the investigation of very small measurement volumes. Due to the small thickness of the single layers in multi-layered microsystems the X-rays penetrate in many cases the samples deeply and diffraction patterns of different materials layers occur. Using new X-ray optics like fibres and mirrors, the size of the measurement spots can be reduced up to very small lateral dimensions without unacceptable losses of intensity. As a result of this miniaturisation the material within the measurement volume more and more differs from the polycrystalline state. In this situation new detection systems like area detectors can be used successfully and new evaluation procedures are required.