Nanoscale selective-area epitaxial growth of Si using an ultrathin SiO2/Si3Ni4 mask patterned by an atomic force microscope

We report selective epitaxial growth of Si using an ultrathin bilayer mask. The key feature of this process is direct writing of nanoscale patterns by means of local anodic oxidation of a Si3N4 layer using an atomic force microscope operated in air. Windows for selective growth are defined by wet etching of the locally oxidized regions. High growth selectivity upon chemical vapor deposition of Si is accomplished by employing the bilayer mask structure which is formed by oxidizing the Si3N4 surface and then selectively desorbing SiO2 in the windows. High-quality homoepitaxial growth is verified by transmission electron microscopy. We also report a simple plasma-treatment technique which solves the problem of retarded SiO2 desorption in the nanoscale windows.