DETERMINATION OF LATTICE STRAIN IN LOCAL ISOLATION STRUCTURES BY ELECTRON-DIFFRACTION TECHNIQUES AND MICRO-RAMAN SPECTROSCOPY

To investigate the stress fields in local isolation structures, convergent beam electron diffraction (CBED), electron diffraction contrast imaging (EDCI) and micro-Raman spectroscopy (mu RS) have proved to be powerful, complementary techniques. CBED and EDCI have a higher spatial resolution with respect to mu RS but need elaborate sample preparation procedures to obtain thin cross sections of the structure. On the other hand mu RS can measure stresses in the silicon substrate provided the overlayers are transparent; moreover, the recorded Raman shift is a convolution of shifts due to different stress components. The results of preliminary experiments performed on LOPOS structures having linewidths in the range 0.5-5 mu m are reported and critically compared.