Application of ellipsometric and interference methods in MOS structures investigations

Changes in some electrical and photoelectric parameters in the plane of aluminum gate, particularly in the effective contact potential difference (ECPD or φMS factor) have been observed in MOS System Studies Department of Institute of Electron Technology for the first time. It has been found that the MS distribution over the gate area has a characteristic domelike shape, with the highest values ate the center of the gate, lower at the gate edges and still lower at gate corners. In order to find out why these values were changed in such way, we have investigated optical properties of the dielectric in the neighborhood of metal gate. Hence, in this work, interferometry and spectroscopic ellipsometry as well as scattered Raman radiation analysis have been used in the investigation of metal-oxide-semiconductor (MOS) structures. The above mentioned methods turned out to be very useful for the possible explanation of changes in photoelectric characteristics of MOS structures with aluminum gate