Cairns,

there is no way to help you unless you provide more details
about the wafer handling mechanism in your PVD tool.

Maybe the stress of your nitride layer is so different from
the oxide layer that the handling can't cope with the different wafer
warpage?

 >I have the one problem which is happened in the etching chamber of PVD
 >tools.
 >When I finished the etching process then I reload the nitride wafer,
 >the wafer
 >will shift in the chamber.
 >If I using the oxide wafer, it will be fine.
 >Does any body talk to me what's force to make  the wafer moving?

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