Molecular dynamics study on mold fracture by nanoscale defects in nanoimprint lithography

Molecular dynamics simulation is performed to study the yield stress and fracture mechanism of single crystalline silicon mold with notch-defect structures. From the stress distribution, it is found that the stress is concentrated near the notch defect and the notch acts as a trigger of the crucial mold fracture. The yield stress with a nano scale notch on the mold sidewall deteriorates more than 7.5 % compared to a defect-free mold. It is found that a surface damage such as notch defect is significant for strength deterioration of the mold. This result shows that the surface defects on the sidewall, which could be induced during the mold fabrication process such as dry etching process, causes serious failure.