Development of a compact time-of-flight mass spectrometer with a length of 1 m for processing plasma diagnostics

It is desired that mass spectrometers should be compact and cost effective for use a's diagnostic or monitoring tools. We examine the factors which restrict the optimum value of mass resolution attainable for time-of-flight mass spectrometers (TOF-MSs) of compact size. We have developed a 1 in long TOF-MS to diagnose plasma processes. As basic specifications, we obtained a wide mass. range of over 20,000 u/e as well as a high mass resolution of up to 2,500. We succeeded in observing various kinds of positive and negative ionic polysilane molecules in addition to the neutrals in a demonstrative diagnosis of the typical silane plasmas relevant to the deposition of the hydrogenated amorphous-silicon thin-film solar cells. This diagnostic system may be a versatile and powerful tool to investigate the detailed reaction processes in various processing plasmas for thin-film deposition and surface treatment.