HYDROGEN PEAK CONCENTRATION IN THE SIO2 SI TRANSITION ZONE AS A FUNCTION OF OXIDE FILM THICKNESS/

Hydrogen depth profiling using the N-15 nuclear reaction analysis meth od performed on silicon oxide layers which are thermally grown at 700 degrees C in a water steam atmosphere and subsequently chemically thin ned at room temperature shows a new effect: The hydrogen peak in the S iO2/Si transition zone depends on the remaining oxide film thickness. Secondary neutral mass spectroscopy (SNMS) measurements show in additi on that the transition zone width also depends on the remaining oxide thickness. The hydrogen migration in SiO2 and in the transition zone i s explained by a new dopant transport model where the flux of the dopa nt ions in solids includes two non-Fickian terms besides the Fickian a nd drift component. One of these terms is caused by the gradient of oc cupiable sites whose concentration seems to depend on the width of the transition zone.