Dual gate oxide formation using ISSG selective oxidation on 2nd thin oxide without influence on 1st thick oxide thickness

From the history of dual gate oxide formation in semiconductor industry, both thick and thin oxides are using conventional furnaces for oxide formation. In recent years, with more miniaturization technology and devices, RTP (rapid thermal processing) method becomes more popular of gate oxide formation. However, both thin and thick gate oxide thickness control has become more important and stringent, as the 2^nd oxide formation will have a significant influence on the 1^st oxide thickness. In this study, a better understanding of dual gate oxide formation using ISSG (in-situ steam generation) on 2^nd thin oxide is introduced. ISSG oxidation will have very little or no influence on the 1^st thick oxide thickness, and showed the potential candidate on 2^nd thin oxide for dual gate oxidation. This will give the flexibility advantage for the dual gate oxide formation and processes robustness development for future device.