We are running into some difficulty with the lift-off of our evaporated metals, specifically gold. We are thinking that we may be overheating the substrate during the evaporation process, or even cooling the finished evaporation too quickly. Some info: we are using a BOC Edwards Auto 306 evaporator. We evaporate at pressures within the -6 Torr, and use a gun current of aprox. 130 mA for Gold, along with a sweep of 2 Hz.
Could we be overheating (cooking) the Photo-resist with such high currents over such long times (aprox. 30 min for 100 nm) ?
We may not be depositing fast enough. Should we push the gun harder and try to evaporate at a higher rate? (We are hesitant to go much higher in current, however.)
If we don't cool gradually after evaporation, will this negatively affect the evaporated layer of Gold and its adhesion to the substrate?
Thank you for any advice you may be able to provide.