HYDROGEN DETERMINATION IN SI-RICH OXIDE THIN-FILMS

Quantitative in-depth distribution of the elements contained in silico n-rich oxide thin films deposited on single-crystal silicon by low tem perature plasma-assisted deposition has been performed by a combinatio n of various MeV ion beam techniques. The quantity of oxygen and nitro gen has been measured by nuclear reactions, the silicon content has be en determined by Rutherford backscattering, and elastic recoil detecti on was used for hydrogen. All the samples contain not only Si and O, b ut also N and H, which are residuals from the reactions involved in th e deposition process. We did find that the MeV beam used in the nuclea r techniques can induce a process of hydrogen desorption, which causes the measured H content to be a function of the He dose received by th e sample. This phenomenon, not previously reported, must be taken into account to give the comet H content. The study of the kinetics of the He-induced hydrogen desorption has been used to correct the experimen tal data and to determine the original hydrogen content. The correctio n factor is in most of the cases close to 2 and outside any experiment al error. Moreover the studies of the kinetics give information on the kinds of hydrogen complexes contained in the films. The results sugge st that, on the basis of the strength of the binding energies, hydroge n is present in at least two different configurations, weakly and stro ngly bonded. In the first configuration hydrogen is easily desorbed ei ther under the action of the ion beam or of the heat treatment at 600 degrees C, in the second, hydrogen is lost only after treatment at 900 degrees C. (C) 1996 American Institute of Physics.