Selective-area formation of Si microstructures using ultrathin SiO2 mask layers

We have developed a technique to form Si microstructures at preassigned positions on Si substrates. The key element of this technique is resistless patterning of ultrathin SiO2 mask layers by direct electron-beam exposure. Selective-area growth of Si was accomplished by two different chemistries: flow-modulated plasma-enhanced chemical vapor deposition (CVD) at 473 K or ultra-high-vacuum CVD at 853 K. Epitaxial deposition was achieved by the latter growth method when a mask layer with minimum thickness for deposition selectivity (approximately 0.2 nm) was employed.