The Prevention Of Metal Contamination In Ion Implantation

Thinner the gate oxide is, narrower the CD is, more important and urgent the metal contamination in ion implantation process is. Especially, when the technology goes to 90nm, the electronic parameter of wafer will be impacted much more by metal contamination. It becomes an important topic that how to control the metal contamination in ion implantation to keep high yieldThrough the study of ion implantation, it is found that there are two main sources of metal contamination. One is the equipment; the other is the manager of manufactory. The reason on equipment includes wrong usage of ionization material in ion source area and serious sputtering on the whole beam path. In the management of production, because of miss in defining rules, many split run card tests and daily monitor tests will induce very serious metal contamination cases.Most of equipment vendors add silicon layer to reduce and avoid metal contamination, which can work obviously only in short term. And it can not used as the electrode, even ion source. After improvement, we use W as a new ionization material, which is far away from doping elements in the mass electrodes, so that we can prevent sputtering and contamination in beam line.Developing and adding"E-run-card"system and"auto-monitor"system in Fab MES system can reduce the miss-operation by operators, and make it easy for production. Also, it can reduce the possibility of metal contamination in ion implantation process, improve the yield.About the measurement of metal contamination, we use both of daily TXRF and SIMS by cases, instead of SIMS only. Not only we can inspect on all tools for long term, and also we can study some single and special case, which make us improve the quality of inspection and control the cost of monitoring...