Nanoimprint Fabrication and Thermal Behavior of Atomically Ultrasmooth Glass Substrates with 0.2-nm-Height Steps

We examined the conditions for the development of atomically stepped ultrasmooth surfaces on commercial silicate glass substrates by the thermal nanoimprint technique using sapphire ($\alpha$-Al 2 O 3 single crystal) molds with 0.2-nm-height atomic steps. Under the pressing conditions of 3 MPa, 300 s, and 610 °C for imprinting, a 0.2-nm-high stepped and atomically ultrasmooth terraced surface could be formed on soda-lime silicate glass substrates having the glass transition temperature of 521 °C. We found that the 0.2-nm-height step structure of the imprinted glass surface disappeared after annealing at 490 °C, and the smoothness of the terrace increased.