Kazutaka Takizawa

Fabrication of sub-10-nm pattern using diblock copolymer

Fabrication of 16 nm pitch L&S pattern was investigated by applying self-organizing material as etching mask. For the purpose, diblock copolymer template composed of polystyrene-polyethyleneoxide (PS-PEO) and spin-on-glass (SOG) was utilized. The material was prepared to form polystyrene cylinder phase in PEO phase. SOG was located in the PEO phase, because of its hydrophilic property. After spin-coating on a Si wafer, film was baked at high temperature. By the thermal treatment, PS cylinder phase was eliminated to form cavities in the cured SOG matrix. Using the cured Si matrix pattern as etching mask, Si substrate was etched. When baking was carried out at 300° C, bridge-like defects were observed on Si pattern. The thermogravimetric examination indicated the baking at 400° C could reduce the defects. Applying the optimized process, 16nm pitch L&S pattern was transferred on Si substrate.

Curing process of silsesquioxane in self-organized diblock copolymer template

In the case that a self-organized diblock copolymer pattern is applied as an etching mask, one of the polymer components is required to have a high etching durability similar to that of silicon oxide. One suitable material for the purpose is a mixture of polystyrene-b-polyethyleneoxide (PS-PEO) and silsesquioxane (SSQ). After phase separation, the SSQ component is located only in PEO phase. By the following post-treatment, the polymer component was removed and residual cured SSQ structure was formed that could be available as etching mask. In this study, the authors investigated post-treatment process of SSQ in the mixed component system, comparing thermal treatment and oxygen plasma treatment. A significant difference was observed in the vertical shrinkage of the film thickness formed on a Si wafer. The plasma-treated film shrank to 72% of the baked film. By the examination of behavior of PS phase and PEO phase during post-treatment, respectively, it was found that the difference was caused by the curing...