Contribution for the optimization of the vapor phase decomposition technique

This paper discusses the vapor phase decomposition (VPD) method used to collect metals from wafer surfaces prior to inductive coupled plasma mass spectrometry, atomic absorption spectrometry, or total X-rays fluorescence analysis. From a low limit of detection (LLD) point of view, the VPD protocol was analyzed to study the possible parasitic contamination introduced by each elementary step. The critical steps were identified and optimized in order to minimize detrimental impact on LLD. Finally, an order of magnitude improvement was gained by modifying the VPD reactor conditioning and using ultra high purity chemicals. The contamination recovery during the droplet collection step was studied for several metals as a function of the collection chemistry. It is shown that the kinetic plays a key role on the collection efficiency of metallic contamination.