Characterization and modeling of out-diffusion of manganese and zinc impurities from deep ultraviolet photoresist

The radioactive tracer technique was applied to investigate the out-diffusi on of manganese and zinc impurities from deep-ultraviolet (DUV) photoresist . Two important process parameters, viz., baking temperature and the type o f substrate (i.e., bare silicon, polysilicon, oxide, or nitride), were eval uated. Our results indicated that diffusion ratios were ail below 6%, irres pective of the substrate type and baking temperature. The substrate type di d not appear to strongly affect the metallic impurity out-diffusion from DU V photoresist. However, solvent evaporation was found to have a significant effect on impurity diffusion. A new model, together with a new parameter, was proposed to describe the out-diffusion behavior of impurities from DUV photoresist. This model could explain the diffusion ratio of metallic impur ities in photoresist layers under various baking conditions. The effectiven ess of various wet cleaning recipes in removing metallic impurities such as manganese and zinc was also studied. It was found that (i) bath life due t o temperature change can considerably affect the cleaning efficiency, and ( ii) hot water immersion can effectively dissolve the impurities from the wa fer surface. (C) 1999 The Electrochemical Society. S0013-4651(98)11-080-7. All rights reserved.