A Highly Sensitive Inorganic Resist for Directly Fabricating Thermally Stable Oxide Pattern on Si Substrate by Low-Energy Electron-Beam Direct Writing

A simple process of 1-keV-range low-energy electron-beam direct writing (LE-EBDW) is proposed for a direct pattern of a thermally stable oxide layer on a Si substrate. An ultrathin multilayered structure is used as a highly sensitive inorganic negative resist for LE-EBDW, and it consists of an amorphous GaAs layer of 3 nm thick and its surface oxide. The EB-irradiated area is transformed into a thermally stable oxide pattern by heating the substrate to 750 °C in a vacuum after LE-EBDW. The heating process induces removal of the multilayered structure, while the oxide pattern can remain on the substrate. The remaining pattern can directly act as an ultrathin template for successive selective area growth on the Si substrate. It is assumed that the pattern is composed of thermally stable oxides such as SiO 2 and Ga 2 O 3 formed below the amorphous layer, not the surface oxide, of the multilayered structure.