Si Pillar Formation and Height Countrol by Furnace Oxidation of the Si (111) Surface with Ultra-Small SiN Nuclei

Lithography-free Si pillar formation has been demonstrated by SiN nucleation and subsequent selective oxidation steps, where nm-scale SiN nuclei thermally formed on the clean Si (111) surface were planned to be used as oxidation masks. In this experiment, dry oxidation at 800°C in a furnace was employed as the oxidation step. As a result, Si pillars were successfully formed and the arrangement of the pillars was mostly random but partially characteristic, reflecting that of the original SiN nuclei. It was found, however, that average pillar height decreases with decreasing nitridation temperature, indicating the imperfect mask ability of low-temperature SiN. This result is ascribed to the formation of SiON during oxidation, which has an inappreciable blocking effect for oxygen diffusion.