Applications de la spectroscopie Raman et photoluminescence polarimétriques à la caractérisation des contraintes dans les structures semi-conductrices à base de silicium, germanium et d'arséniure de gallium

摘要

Nowadays, the increase in performance and the reduction of the dimensions of the microelectronics or optical components integrated in electronics or optronics systems requires non-destructive characterization techniques, capable of probing micro and nano-objects. In this context, Raman spectroscopy and photoluminescence techniques represent characterization tools capable of analyzing locally the mechanical strain, introduced into actual semiconductor devices in order to boost their performance. This PhD thesis work aimed at two objectives, enlarging the capabilities of the polarimetric Raman spectrometer including the addition of a luminescence detection system and applying the developed techniques and methodologies to characterize strain in silicon-, germanium- and gallium-arsenide-based semiconductors structures. After an experimental study of the pertinent system parameters such as depolarization, retardation and dichroïsm necessary for combining a conventional Raman spectrometer with a polarimeter, we showed that the calibration of the system depends on the excitation source wavelength, as well as on the nature of the scattered light (Raman or Rayleigh). From applications viewpoint, we measured mechanical strain in silicon nanostripes (15 nm thick) and germanium microstripes by using previously developed measurement methodology. The results obtained were analytically modeled to highlight the physics of the observed phenomena. Thus, we showed that it is possible to enhance the Raman signal in the silicon nanostripes through appropriate polarization control of incident and scattered radiations. The implementation of the photoluminescence technique with control of the polarization states, in addition to Raman spectroscopy, allowed us to extend the range of mechanical strain measurements in semiconductor structures. Actually, by using this technique we are capable of measuring residual stresses of the order of 20 MPa which is beyond the capability of conventional Raman spectroscopy being essentially limited by the spectral resolution.