A SURFACE CHARGING TECHNIQUE IN PHOTOEMISSION SPECTROSCOPIC STUDIES OF DIELECTRIC-SEMICONDUCTOR STRUCTURES

A surface charging technique used in conjunction with x-ray photoelectron spectroscopy (XPS) has been applied as an in situ surface analytical tool for the studies of the fabrication of dielectric-semiconductor structures. It was found that the measurements of surface composition and Fermi level position by XPS gives useful information on the effects of in situ surface modification prior to the deposition of the dielectric film and on the properties of the dielectric-semiconductor structure. When the thin dielectric film thickness is within 10 nm, XPS yields information on both the dielectric film and the semiconductor at the interface, and thereby allows the monitoring of the initial growth of the dielectric film. In addition to this conventional approach, surface charging of the thin dielectric film during XPS analysis, either by photoemission or by flooding the surface with low-energy electrons, provides additional information on Fermi level stabilization of the semiconductor at the insulator-semiconductor interface. Furthermore, the charging potential associated with a local impurity in the sample structure can be used to estimate the depth location of the impurity. The measurement of the degree of charging also gives information on the electrical properties of the dielectric.