Characterization of Optically Induced Periodic Structures on Semiconductor Surfaces

Increasing applications are being found for laser and optical techniques in the fabrication of semiconductor devices and in the diagnostics of processing steps such as etching or metal deposition. For example, by using two interfering laser beams to initiate localized chemical reactions, spatially periodic structures can be produced on semiconductor surfaces. Practically, such structures are of interest because of the potential for utility in a variety of electrooptical and electronic applications.1 An important aspect of this processing is that the structure growth can be monitored in real time by observing the diffraction of the writing beams, thus allowing a precise control over the feature depth. In addition, because the structures can have a high spatial frequency, the process of their fabrication becomes a method of studying the wavelength-scale physical processes which influence the structure growth. These processes may involve, for example, the diffusion of photoexcited species or the magnification of the optical fields at the illuminated surfaces.