Modeling nanoporosity development in polymer films for low-k applications

The bubble growth dynamics of a polymer supersaturated with CO2 have been modeled for micron-size films after nucleation. The model equations are based on the shell model of Arefmanesh, Advani, and Michaelides in which a nucleated bubble is surrounded by a finite concentric shell of polymer supersaturated with gas. Bubbles grow by mass transfer of dissolved gas from this shell. The model is extended to allow for diffusion of dissolved gas out of the shell in addition to diffusion into the bubble. A parametric analysis is performed to examine the effects of film thickness, temperature, diffusivity at the T. and Henry's law constant. (c) 2005 Society of Plastics Engineers.