I am trying to remove a thin layer (~5nm) of copper oxide layer on PZT. Is there a way to etch away the copper oxide without attacking the PZT layer underneath?
You can use copper etchant form Sigma Aldrich. Ideal for spray etching of copper. Ferric chloride based Cu etchant with etch rate of 0.5 mil/min @ 40 °C.
You can also do it using PECVD system and carbon tetrafluoride gas. But you have to optimize the etching time and plasma power.