Hi Dan- thanks for your reaction. Is it possible our oxygen is coming from the chamber?------- I probably do not get the point , but we clean the chamber everytime when it un/load the sample. Is the system load-locked?-------Yes What base pressure are you pumping to before the start of deposition?--------5E-7 How long are the samples held at base pressure before the start of deposition?----------- I do not know excatly, but we leave the sytem pumping down overnight and in the morning we start grow the film. I am unsure if I am saying it right but I am wondering if there is any restriction for substrate-target distance, also I have read that the substrate has to be baked and cleaned firstly for a certain time before the deposition. what do you think? Many thanks, Yassine,Ait El Aoud On Wed, Jan 26, 2011 at 2:12 PM, Ruiz, Marcos Daniel (SENCOE) < Dan.Ruiz@honeywell.com> wrote: > Is it possible our oxygen is coming from the chamber? > > Is the system load-locked? > > A load-lock will prevent air and moisture from entering the deposition > chamber, so clearly that would be preferable. > > What base pressure are you pumping to before the start of deposition? > How long are the samples held at base pressure before the start of > deposition? > > Pumping to and holding at a low base pressure works to remove air and > moisture introduced during loading. Lower base pressure and longer pump > times are preferable. > > Dan Ruiz