| Popis: |
The combined effects of diffraction, refraction, reflection, and interference often result in the notching of photoresist lines at steps in the substrate. Dyes have been added to photoresists in order to minimize the notching problem. However, it has not been clear whether the improvement has been due to the optical absorbance of the dye, the effect of the dye on the dissolution rate of the resist or both. The objective of the work reported here is to gain insight into the nature of the problem and its solution in order to allow the most efficient approaches to be utilized. The Dill model of exposure and development is used as a tool to evaluate the effects of various dye additions to a conventional positive photoresist. The functional absorbances, nonfunctional absorbances, and photo-decomposition rates are compared at 436 nm and 405 nm. Dissolution rate versus relative inhibitor concentration curves are compared for both metal ion containing and metal free developers. Characteristic curves are presented which demonstrate the effects of the dyes on photospeed and contrast. These effects are separated into the portion due to the optical absorbance of the dye and the portion due to the effect of the dye on the dissolution rate of the resist. |
