Comparison of submicron particle analysis by Auger electron spectroscopy, time-of-flight secondary ion mass spectrometry, and secondary electron microscopy with energy dispersive x-ray spectroscopy

Particulate contamination can result in a significant yield loss during semiconductor device fabrication. As device design rule dimensions decrease the critical defect size also decreases, resulting in the need to analyze smaller defects. Current manufacturing requirements include analysis of sub-0.5-mu m defects, with analysis of sub-0.1-mu m defects expected in the near future. This article investigates the particle analysis capabilities of Auger electron spectroscopy, time-of-flight secondary ion mass spectrometry, and energy dispersive x-ray spectroscopy during scanning electron microscopy (SEM/EDS). In order to evaluate each method carefully, a standard set of samples was prepared and analyzed. These samples consist of 0.5-, 0.3-, and 0.1-mu m Al and Al2O3 deposited on 1-in. Si wafers. Although all the methods observed an Al signal, a semiquantitative gauge of capability based on the relative strengths of particle versus substrate signal is provided. The dependence of the sample-to-substrate signal on primary electron energy is examined for both EDS and Auger analyses. The ability to distinguish metallic Al particles from Al oxide particles for the three techniques is also discussed. (C) 1996 American Vacuum Society.