Additional peaks in mass spectra due to charge exchange events and dissociation of molecular ions during extraction

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• 作者：Volker Hä ; ublein ; Lothar Frey and Heiner Ryssel
• 关键词：Mass interferences ; Contamination ; Ion implantation
• 刊名：Nuclear Instruments and Methods in Physics Research Section B ; Beam Interactions with Materials and Atoms
• 出版年：2005
• 期刊代码：42_0168583x
• 类别：ph
• 出版时间：2005
• 卷：237
• 期：1-2
• 页码：346-350
• 文件大小：187 K

摘要

It is well-known that charge exchange events and dissociation of molecular ions after extraction and prior to mass analysis result in changes to a so-called apparent mass of the ion and increase the possibility of energetic contamination in ion implantation. It was found that if charge exchange events and dissociation of molecular ions already take place during extraction, additional peaks occur in a mass spectrum. They were observed for all of the used source feed materials, such as AsH₃, BF₃, and argon. In this paper, the origin of these peaks is discussed and a model that calculates the apparent mass as a function of the extraction voltage is presented.