The relationship between structural and electrical properties of the post-deposition annealed Er2O3/n-Si hetero-structures

Abstract

This study presents comprehensive results on the structural modifications of Er2O3/n-Si hetero-structures under post-deposition annealing (PDA) and the effects of these changes on the electrical characteristics of the Al/Er2O3/n-Si/Al MOS capacitors. The Er2O3 films were grown on n-Si substrate with RF magnetron sputtering and annealed under nitrogen at RT, 300 °C, 500 °C, 600 °C, 700 °C. The increasing grain size of the films up to 300 °C did not show a significant change in other annealing temperatures. The erbium silicate content in the RT and 600 °C-Er2O3/n-Si interface is quite higher than those of 500 °C and 700 °C, while a silicate-like layer was not found at 300 °C. The highest dielectric constant (ε) value was obtained from the 500 °C-Er2O3 MOS capacitor due to the lowest oxygen deficient bond content. It was found that Qeff values tend to increase as the oxygen concentration decreases in the film. It was determined that Er-Er oxygen deficient bonds may have acted as negative charge trap centers. Although the Er-M content in the 700 °C-Er2O3/n-Si is higher than that of 500 °C, lower Qeff values were obtained from the 700 °C-Er2O3 MOS capacitor due to the higher Si-Si oxygen deficient bond content, which is most likely act as a positive charge trap center. It was concluded that the contributions of oxide trap and interface trap charges should be evaluated together in establishing a link between electrical characteristics and structural analyses.