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</o:shapelayout></xml><![endif]--></head><body lang=EN-US link=blue vlink=purple><div class=WordSection1><p class=MsoNormal>At CNS, Harvard University, the gas line from the close valve in the gas box to the PECVD deposition chamber has been contaminated twice, which resulted in the deposited films with spots patterned same as the gas holes of the shower head. These spots are clusters of micro-particles. Gases connected with this tool include: pure SiH4, N2O, NH3, N2 for silicon nitride and oxide depositions and CF4, O2 for etching back the coatings on the chamber wall. <o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Has anyone had a similar experience and how did you solve the problem?<o:p></o:p></p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Thanks,<o:p></o:p></p><p class=MsoNormal>Ling Xie<o:p></o:p></p><p class=MsoNormal>Center for Nanoscale System<o:p></o:p></p><p class=MsoNormal>Harvard University<o:p></o:p></p><p class=MsoNormal>617-496-9069 (o)<o:p></o:p></p><p class=MsoNormal>617-780-1821 (cell)<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p></div></body></html>