Silver RF magnetron sputtering targets

[spearme]

Hi,
I'm hoping someone out there can help me. I've vented my system to clean her out this week and as I was checking my targets I noticed that the whole sputtering surface of my silver target was white. I've been able to clean the white layer off but have no idea what it is or how it happened! Do old silver targets just turn white after long use or do I have some contamination in my system!
Thanks in advance for any help.

 

[Vagn]

One possibility is simply that the surface of the target is rough, and reflecting light in a diffuse manner. Otherwise, perhaps you had a thin oxide layer on your target? You could use XPS/EDX to investigate the composition of your last grown material, and see if there is any other contaminant there?
How did you manage to remove the white layer?

 

[spearme]

Thanks for the advice!
My depositions of late have been slightly off from what I expected but I think that it has been down to my thickness monitor needing a new crystal rather than the silver as EDX tells me they're pure silver films.I don't think its an oxide layer,as I'm under the impression that silver oxide is black. Surface roughness isn't a bad idea at all! I'll have a look into that and see what comes up. To clean the target surface I used a Dremel tool with to polish the surface back to silver.
Thanks a lot!