Influence of argon pressure on the depth resolution during GDOES depth profiling analysis of thin films

Abstract

The influence of Ar pressure on depth resolution during glow discharge optical emission spectroscopy (GDOES) depth profiling has been examined through the use of 358 nm thick anodic alumina films grown over flat aluminium surfaces. The films are ideal standards for the present purpose, being amorphous and highly uniform in thickness, with a flat and sharply-defined metal/film interface. The depth resolution is influenced strongly by the Ar pressure, which, in turn, is related to the shapes of the craters generated by cathodic sputtering. For a given power, an optimum Ar pressure results in a flat-bottomed crater and the highest depth resolution is realized. In the present example, the highest depth resolution, expressed in terms of width of the transition of the aluminium profile at the metal/film interface, i.e. ∼7 nm, was achieved at a pressure gauge voltage of 5.60 V (0.41 mbar) and a power of 40 W. Increase or decrease of Ar pressure from the optimum leads to rapid degradation of depth resolution. Copyright © 2000 John Wiley & Sons, Ltd.