Developer-induced debonding of photoresist from copper

We describe the debonding of a polymeric photoresist film bonded to a thin copper substrate as a result of the diffusion of an organic penetrant into the polymer. The diffusion profile (measured by Rutherford backscattering spectroscopy) consisted of a uniformly swollen layer behind a sharp front which propagated into the polymer at a uniform velocity. Debonding always occurred when the front had penetrated about 12 µm into the polymer (about ⅕ its thickness). The debonding was driven by the release of elastic strain energy created by the swelling.