Improving the detection limits for vapor phase decomposition-inductively coupled plasma mass spectrometry (VPD-ICP-MS) analysis

Abstract

Semiconductor industry roadmaps are driving device geometries into the 0.13 micron range. Implementing smaller device dimensions requires cleaner chemicals and, more importantly, cleaner production processes. Vapor phase decomposition (VPD) is a method by which trace elements on the surface of a silicon wafer are collected into a liquid sample. Inductively coupled plasma mass spectrometry (ICP-MS) analysis of the resulting liquid sample is a direct approach for measuring the cleanliness of production processes run in the wafer fab. Required analytical measurements at <10⁸ atoms cm⁻² have forced the need for lower detection limits, lower instrument background, higher sensitivity and well-controlled analytical blanks in VPD-ICP-MS analysis. This paper will discuss measures taken to improve detection limits for VPD-ICP-MS analysis through improved measurement methods using high resolution ICP-MS and the elimination of potential contaminants during the VPD sample preparation procedure.