IMPROVED POLYIMIDE POLYIMIDE ADHESION VIA SWELLING AGENT ENHANCED INTERDIFFUSION

In this study, the polyimide underlayers were cured at a maximum temperature of either 350 or 400°C. The dry films are in a glassy state at room temperature but expand and plasticize upon sorption of strong swelling agents. For the 5μm films used (on silicon substrates), 80%-90% of this thickness increase is reached after 24 h in NMP (N-Methyl-2-Pyrrolidone) at room temperature or about 0.5 h in NMP at 85°C. The authors data are found to be consistent with the initial hypothesis that adhesion strengthening interdiffusion in polymer systems can be fostered by the structural and rheological changes brought about in the polymer underlayer by the sorption of a strong penetrant. This adhesion-enhancing technique is convenient and expected to be extendible to other polymer/polymer systems. Applications of practical importance include adhesion improvement in microelectronic devices containing multilayer polymer structures.