Development and Evaluation of an Innovative “Soft Ionization Technique” Based on Atmospheric Pressure Glow Discharge Time-of-Flight Mass Spectrometry (AP-GD-TOFMS) for the Determination of Inorganic/Organic Contaminants on Semiconductor Surfaces

By: Jorge Pisonero

31 August 2011


The development of new and innovative “soft ionization techniques” coupled to fast, simple, reliable and robust mass analysers is providing powerful instrumentation able to carry out direct analysis of inorganic/organic compounds on sample surfaces with almost no surface damage. This methodology could open new “research fields” in the direct analysis of semiconductor surfaces with little or no sample pre-treatment. In this project, in particular, an Atmospheric Pressure Glow Discharge (AP-GD) is proposed. Operating with He gas, it will generate a flow of He metastable species, that will be transported outside the discharge chamber and could be directed towards a sample surface. The reactions of the metastables with ambient gas constituents lead to the production of reagent ions that leads to desorption/ionization of the sample surface constituents. Generated ions are then transported into a Time-of-Flight Mass Spectrometer (TOFMS) able to detect both positive and negative ions permitting identification and quantization of the species. AP-GD-TOFMS could provide a fast, simple, reliable and robust analytical method, able to carry out direct analysis of inorganic/organic compounds present on the surface of semiconductor samples (i.e photovoltaic silicon). The spatial resolution could be in the order of ~mm2 allowing mapping of the sample surface, and limits of detection at femto-mol level could be achieved.

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