Impact of LaFMD Treatment on VFB Modulation and Defect Reduction in SiGe Metal-Oxide-Semiconductor Interfaces

Abstract The impact of LaFMD treatment on flat band voltage (VFB) modulation and defect reduction in SiGe metal-oxide-semiconductor interfaces is investigated in detail. A comparative analysis is conducted on HfO2/IL/Si0.7Ge0.3 gate stacks treated with La2O3 and La(iPr2-FMD)3 (LaFMD). While La2O3 treatment achieves a VFB modulation of 220 mV, the interface state density (Dit) increased significantly from 4.11×1012 eV-1·cm-2 to 2.22×1013 eV-1·cm-2. In contrast, LaFMD treatment realized a superior VFB modulation of 330 mV and reduced Dit to 7.43×1011 eV-1·cm-2. The better interface properties of LaFMD treatment can be attributed to the suppression of GeO formation in the interface layer (IL). Conversely, La2O3 treatment promoted the formation of GeOx and SiOx, which increases interface defects. Additionally, the larger VFB modulation achieved by LaFMD is due to the formation of a LaSiOx-rich IL. However, La2O3 treatment resulted in an initial oxide layer that positioned its LaSiOx layer farther from the Si0.7Ge0.3 substrate, thereby weakening the modulation ability.