Analysis of local mechanical stresses in and near tungsten lines on silicon substrate

The mechanical stresses in tungsten lines on a silicon substrate were determined by x-ray diffraction (XRD). The stresses are found to be plane and tensile. The stresses induced in the silicon substrate are compressive under the lines, but tensile in between the lines. This stress state in the silicon substrate was studied by micro-Raman spectroscopy (mu RS). A good correlation is found between the XRD results and the mu RS results. The stresses determined by XRD and mRS were compared to the stresses calculated using two analytical models and a numerical approach. The best fit to the experimental results was obtained when using the distributed edge force model. It is shown that the combination of both XRD and mu RS provides a useful way to test the validity of the assumptions which are used in the stress models. (C) 1999 American Institute of Physics. [S0021-8979(99)04309-1].