I've deposited a thin film of both sides of a wafer and I'm trying to determine the stress using a profilometer wafer bow measurement and Stoney's formula. At first the wafer was flat. After double side deposition it got a strong negative bend (the center is depressed) and after removing the backside the bend relaxed to an intermediate value. This is my first time doing stress measurements and I can't process what this means. In my mind a negative bend means the residial stress is compressive because the film is on the concave part of the bent wafer, but I see some publications treat it the other way. I have the magnitude of the stress but I can't figure out the sign.
Please refer to my research articles, available at research gate, if further doubt u can ask again
Nagesh Sharma Thank you very much, your 2019 paper in Indian Journal of Physics was very helpful, especially figure 3. Do I understand correctly that compressive stress means that the film is compressed before relaxation?
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