VISIBLE LUMINESCENCE FROM ONE-DIMENSIONAL AND 2-DIMENSIONAL SILICON STRUCTURES PRODUCED BY CONVENTIONAL LITHOGRAPHIC AND REACTIVE ION ETCHING TECHNIQUES

Visible luminescence from silicon nanostructures fabricated by using conventional lithographic and reactive ion etching techniques and final thinning by high temperature thermal oxidation was obtained at room temperature under 488 nm argon laser excitation. Highly anisotropic vertical silicon pillars with aspect ratios as high as 25:1 and diameter below 0.1 μm, as well as silicon walls of the same sizes were first produced, which were further thinned by several cycles of thermal oxidation and oxide removal by HF dip. Sub-10 nm diameter silicon pillars and same thickness silicon walls with height in the μm range were thus produced. The fabrication process involved high resolution deep-UV lithography, highly anisotropic silicon etching, and final thinning of the silicon structures by oxidation and oxide removal. The initial pattern of dots and lines was defined by optical lithography using the well known silylation process. The resolution of the process in dot and line size definition was equal to 0.22 μm but lower dimensions down to less than 0.1 μm were obtained in overexposed regions during dry development in a plasma reactor. Three different masks were used for the silicon etching: Cr or Al metal masks or silylated photoresist, all being resistant to the silicon etchants. Highly anisotropic reactive ion etching was achieved by a process using a mixture of SF6 and CHF3 gases at room temperature.© 1995 American Institute of Physics.