Thickness Variance of Silicon Oxide with Nitrogen Ion Implant

Silicon oxide is widely used for insulation layers of semi-conductor devices, and the thickness of insulation layer typically affects the electric characteristics of semiconductor devices. Non-dopant ion implantation before oxidation is a promising method for controlling the thickness of silicon oxide. For example, steep decreases in silicon oxide thickness after high-dose nitrogen implant are already reported.In the study, the dependence of silicon oxide thickness on nitrogen dose with dry and wet oxidation processes was investigated in detail by intentionally changing the ion dose within a wafer via the SMIT's MIND system. The differences in dose dependence are clearly observed. After each oxidation process, implanted nitrogen atoms are observed as present at extremely near the surface (approximately 2 nm) in silicon oxide, and this is significantly shorter than the implantation depth before oxidation (approximately 30 nm) from the SIMS analysis.The study clearly indicates that the two-dimensional intentional non-uniform nitrogen implant by the MIND system potentially aids in controlling silicon oxide thickness.