In this work, results of stresses measurements in dielectric layer under the gate area of metal-insulator-semiconductor (MIS) structures obtained by means of several methods are presented. The objects of our investigations were Al/SiO₂/Si (traditional), Al/La₂O₃/Si and Poly-Si/SiO₂/Si systems. In these studies, the methods such as interferometry, profilometry and spectroscopic ellipsometry have been applied.

Interference measurements allowed determination of curvature radius of oxidized silicon substrate (by Fizeau interferometer) and analysis of the gate area and the gate vicinity (by MII-4 interferometer). Contact method (by alpha step 200 profilometer of Tencor Instruments Company) gave the directly profile of gate surface and its surrounding. Ellipsometric method (by variable angle spectroscopic ellipsometer) allowed determination of thickness and refractive index of the dielectric layer. In this paper, we mainly focused on the investigation of changes in the shape of the gate surface which ocurres sometimes after annealing of the gates at temperature of 450^oC. To analyses of obtained measurements results, model based on Stoney formula and its later modifications were used.