원자현미경을 이용한 탄화규소 (SiC)의 국소산화

Abstract

The local oxidation using an atomic force microscopy (AFM) is useful for Si-based fabrication of nanoscale structures and devices. SiC is a wide band-gap material that has advantages such as high-power, high-temperature and high-frequency in applications, and among several SiC polytypes, 4H-SiC is the most attractive polytype due to the high electron mobility. However, the AFM local oxidation of 4H-SiC for fabrication is still difficult, mainly due to the physical hardness and chemical inactivity of SiC. In this paper, we investigated the local oxidation of 4H-SiC surface using an AFM. We fabricated oxide patterns using a contact mode AFM with a Pt/Ir-coated Si tip (N-type, 0.01-0.025 <TEX>${\Omega}cm$</TEX>) at room temperature, and the relative humidity ranged from 40 to 50 %. The height of the fabricated oxide pattern (1-3 nm) on SiC is similar to that of typically obtained on Si (<TEX>$10^{15}^{\sim}10^{17}$</TEX> <TEX>$cm^{-3}$</TEX>). We perform the 2-D simulation to further analyze the electric field between the tip and the surface. We demonstrated that a specific electric field (4 <TEX>${\times}$</TEX> <TEX>$10^7\;V/m$</TEX>) and a doping concentration (<TEX>$^{\sim}10^{17}$</TEX> <TEX>$cm^{-3}$</TEX>) is sufficient to switch on/off the growth of the local oxide on SiC.