| The drive towards smaller circuit elements in microelectronics devices is the main technological goal of the semiconductor device manufacturing industry. Today's leading edge integrated circuit devices have critical dimensions of less than 0.20 mum. This reduction in size requires an improvement in lithography technology, which involves the exposure system and the resist. Hence, photoresists play an increasingly important role in semiconductor manufacturing.; Lithographic simulation has become an important tool for the semiconductor industry when implementing new resist formulations. Use of lithographic software results in substantial savings of both time and money, due to its predictive capabilities. However, current software programs do not adequately model the diffusion of casting solvent in photoresists.; Novolac-based photoresists have been used to manufacture billions of dollars worth of semiconductor devices worldwide. These positive-tone photoresists have replaced the earlier negative-tone resists because of their higher resolution and greater dry etch stability. Although this is such a commercially important material, there is a great deal about it that is not understood on a molecular level. Specifically, many factors affect the dissolution rate of the material, yet they have not been quantified.; Chemically amplified resists have grown in importance through the use of exposure tools of lower wavelengths by the semiconductor industry. Acid diffusion has been found to dramatically affect the lithographic performance of chemically amplified resists. On one hand, acid diffusion is needed to reduce the effects of standing waves, however, on the other hand too much acid blurs the latent image. Therefore, knowledge of the diffusion coefficient of the acidic species is needed in order to predict the amount of diffusion that will occur for a given bake condition, and post exposure delay.; This work focused on modeling the diffusion of four common casting solvents in novolac-based films, and acid diffusion in a polymer used in chemically amplified resist formulations. These models can then be implemented in lithographic simulation software. A quartz crystal microbalance has been constructed to make the measurements. |
