Study on annealing effect of Ti-doped Gd2O3 films for high k dielectrics

Abstract

Abstract Rare earth oxides and nitrogen oxides have drawn more and more focus as candidates for next-generation gate dielectrics in MOSFET. In this study, a Gd2O3 film doped with 3% Ti was fabricated through co-sputtering gadolinium and titanium targets in a diluted oxygen atmosphere. A systematic study was carried out to examine the annealing influence on the microstructure, surface roughness, band gap, and electrical properties of this film. Compared with as-deposited film, the annealed sample displays a smaller surface roughness (Ra=0.45 nm) and more excellent electrical performance. In terms of band gap analysis, as the annealing temperature rises from 400 to 700°C, the band gap has fallen from 4.70 eV to 4.63 eV, indicating a smaller value compared to the as-deposited sample (4.73 eV). As a result, the 600°C-annealed thin film shows the most outstanding performance with the largest k value of 23.9. Further, 600°C-annealed and as-deposited films were selected for impedance spectrum analysis and examination of the equivalent circuit. This work can offer a new insight to design novel rare earth oxides with high k dielectric and select the corresponding annealing process.