부산대학교 도서관

The Uniformity of SOI layer thickness is need to be within plus or minus 5%, because an increase of dispersion of the silicon layer thickness increases the characteristic variation of fully depleted SOI MOSFETs. The thickness range of the SOI layer is required to be smaller and smaller, since the thickness of the silicon layer keeps getting thinner and thinner with the miniaturization of MOSFETs. Thus, we attempted to make the thickness uniformity of SOI layer more uniform by numerically controlled (NC) sactificial oxidation using atmospheric-pressure plasma [1]. Figure 1 shows the procedure of numerically controlled sacrificial atmospheric-pressure plasma oxidation using array of electrodes. First of all, the thickness distribution of the silicon layer is measured by spectroscopic elipsometry, and the redundant thickness at each regions is calculated. Secondly, NC plasma oxidation is performed by controlling the plasma-on time of each electrode (Figs 1(a), (b)). The region of atmospheric- pressure plasma is localized around the electrodes, because the mean free path of a gas molecule is very short. Finally, the wafer is dipped into HF solution to reveal the uniform SOI layer (Figs 1(c), (d)).