Feasibility of applying microsecond-pulse glow discharge time of flight mass spectrometry in surface depth analysis

Abstract

This work evaluates the possibilities of applying microsecond-pulse glow discharge time of flight mass spectrometry (mu s-pulse GD-TOFMS) in surface depth analysis. Investigations have been done for effects of discharge pressure on sputtered depth profiles as well as on topographies under mu s-pulse GD mode; and also for influences of discharge current and discharge frequency on characteristics of sputtered surface. Sputtering rates of several pure metals under mu s-pulse GD and dc-GD modes were studied and compared. The estimated erosion rates are 1.27, 2.90 and 5.18 nm s(-1) for pure Fe, Cu and Zn layer, respectively. Depth profiling were conducted for a technical Zr-Fe layer (about 10 mu m) and for a Fe-Cu layer (about 1 mu m) by mu s-pulse GD. A simple model was developed and utilized to convert ion intensity into element concentration, and the experimental results were presented and discussed. Preliminary results show that mu s-pulse GD-TOFMS has a promising future in the area of surface depth analysis, especially in the depth analysis of thin layers and of their cross-sections. (C) 1998 Elsevier Science B.V. All rights reserved.