FABRICATION OF QUANTUM SEMICONDUCTOR STRUCTURES BY HIGH-ENERGY ELECTRON-BEAM LITHOGRAPHY OF AN INORGANIC EPITAXIAL RESIST ON GAAS

Epitaxially grown calcium strontium fluoride on gallium arsenide has b een patterned by high energy electron beam lithography and wet develop ment. Fabrication of lines and dots of 8nm size is reported. Electron diffraction experiments indicate that fluorine is removed under electr on bombardment with the formation of a calcium and strontium oxide. Th e end product of the radiolysis can be selectively etched in an acetic acid solution. A dose requirement of around 2x10(4)C/cm2 was necessar y to form these features but a large dose latitude was observed. Possi ble applications of this epitaxial inorganic resist for the fabricatio n of quantum semiconductor structures are discussed.