ABSTRACT
Various kinds of semiconductor microstructures have been fabricated based on the conventional lithography where a mask pattern is projected onto an organic photoresist on the substrate using light, electron beam, or X-ray. However, these lithographic processes have a potential difficulty in order to reach a nano-scale controllability due to the resolution limits of the mask and the photoresist as well as the wavelength of the light sources used. Therefore, the elimination of both mask and resist from patterning processes by employing a direct writing method using energetic beams is considered to be one way to go in order to directly fabricate nano-scale structures. This simplification is contributed to reduce a number of process steps resulting in the improvement of surface cleanliness. Moreover, a resistless technique is essential for in-situ wafer processing involving direct regrowth of epitaxial semiconductor layers for maintaining device quality at the interfaces.
