The investigation of the germanium distribution for the optimization of the surface reaction process

Abstract In microlithography the surface reaction process is expected to resolve a fine pattern below 0.2 μm. In this process the pattern size control is the most important issue in obtaining high resolution. We evaluated this process using bis(triethylgermyl)amine as the surface reaction agent. The distribution of the germanium in the resist film was evaluated from the dry etching characteristics. This evaluation showed the diffusion of the surface reaction agent was influenced by exposure dose, reaction temperature and reaction pressure. The distribution of the germanium in the resist film determined the resolution, and the reaction temperature was the most fundamental factor to determine the distribution. Then we evaluated the relationship between the temperature and the patterned resist profile. As the reaction temperature became lower the profile became better, because the diffusion of the surface reaction agent was reduced and the germanium was condensed near the resist film surface. On the other hand, if the temperature was too low the profile was not good. The small thickness loss at the beginning of the etching which caused to form the germanium oxide layer was observed. In this case this thickness loss could not be negligible and degraded the profile. © 1997 Elsevier Science S.A.