To estimate the ratio of densification to Vickers indentation volume, three-dimensional images of Vickers indentations on several glasses, including silicate glasses and bulk metallic glass (BMG), were obtained before and after annealing using an atomic force microscope. Large volume recovery of Vickers indentation by annealing was observed for all glasses but BMG. Following previous studies, this recovered volume almost corresponded to the densified volume under a Vickers indenter, and the compositional dependence of densification was discussed. The ratios of densification to the total indentation volume for silica and soda-lime glasses were 92% and 61%, respectively. It was concluded that densification was a general property for silicate glasses and that the ratios of densification to the total indentation volume for all the glasses correlated well with Poisson’s ratios of the glasses.

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Effect of B 2 O 3 content on crack resistance was investigated by indentation tests of glass samples with various compositions of B 2 O 3 . The ternary SiO 2 B 2 O 3 Na 2 O glass system (SBN series) and non-alkaline aluminoborosilicate glass system (SAB series). When B 2 O 3 is substituted with SiO 2 in the SBN system ("SBN1" series), crack resistance has a relationship with density. In a series of the SBN system where density did not change with B 2 O 3 content ("SBN2" series), crack resistance decreased with increasing B 2 O 3 content. On the other hand, crack resistance increased with increasing B 2 O 3 content in the SAB series, where density did not change. According to the results of NMR measurement, boron in 4-cordination state ([4] B) increased in the SBN2 series while boron in 3-cordination state ([3] B) increased in the SAB series with increasing B 2 O 3 content. Therefore, crack resistance increases with increasing [3] B and decreases with increasing[4] B. The difference in structure between [3] B and [4] B containing glasses leads to different effect on residual stress around the indentation, resulting in difference in crack resistance.

A polymer deformation process is studied by numerical simulations and the results are compared with the related experimental results in nanoimprint lithography. The imprint pressures required for successful imprinting and the filling rate into the mold grooves are studied as the aspect ratio of the pattern, initial thickness of the polymer, and the duty ratio of the pattern are changed. The required pressure increases not only for high aspect ratio pattern but also low aspect ratio pattern. Also, the pressure increases when the initial thickness of the polymer decreases to less than about two times that of the groove depth of the mold. These results are explained by the deformation mechanism of the polymer and agree well with the related experimental results. Based on these theoretical and experimental studies, fabrication of a high aspect ratio pattern having 100 nm width and 860 nm height is successfully demonstrated using thick polymer by nanoimprint lithography.

The fracture defect of the polymer in thermal nanoimprint lithography is studied based on numerical simulation and experiments. Hot pressing, cooling, and releasing steps in nanoimprint lithography are investigated in detail by a numerical simulation study. The applied pressure after the polymer deformation below the glass transition temperature will induce a stress concentration at the corner of the polymer pattern. On the other hand, the difference of the thermal expansion coefficients between the mold and the substrate causes lateral strain, and the strain is concentrated at the corner of the pattern. These strains induce defects and cause fracture defects at the base part of the pattern during the mold releasing step. To eliminate the defects, the applied pressure is released below the glass transition temperature, and slow cooling is introduced to relax the stress concentration. The result shows successful fabrication of fine patterns with a high aspect ratio.