Influence of oxygen concentration of Si wafer surface in Si emission on nano ordered three-dimensional structure devices

In past studies, the Si emission phenomenon is one of the issues for fabrication of 3D structure devices such as FinFETs and Vertical MOSFETs. In this paper, it is found that novel Si emission phenomena depending on the surface oxygen concentration of Si wafer occur, when Si pillars patterned less than 100 nm are oxidized. A wafer with high oxygen concentration which is over 1:0×10¹⁸ atoms/cm³ can suppress Si emission from the Si pillar compared to the low oxygen concentration wafers which are less than 1:0×10¹⁷ atoms/cm³. The difference of oxygen concentration in the Si substrate is expected to largely depend on the behavior of oxygen atom in the Si wafer before and after oxidation. In case of an oxygen concentration ratio exceeding the solid solubility of Si, oxygen diffuses outward from the Si substrate after oxidation, whereas oxygen diffuses inward when the concentration is below the solid solubility. It was also found that the larger the degree of injection of oxygen into the Si substrate after oxidation, the larger the emission amount of Si from the Si pillar. Finally, we discuss the mechanism of above experimental Si emission phenomena in nanoscale Si pillar with previous first principle model of silicon oxidation process.