Hydrogen trapping in oxygen-deficient hafnium silicates

Abstract

Isotopic substitution, nuclear reaction analysis, and x-ray photoelectron spectroscopy were employed to show that oxygen-deficient hafnium ͑Hf͒ silicates trap hydrogen atoms. Based on this experimental observation, we used first-principles calculations to investigate the structure, energetics, and electronic properties of H interacting with O vacancies in a hafnium silicate model. We found that O vacancies close to a Si atom are energetically favored when compared to vacancies in HfO 2 -like regions, implying that close-to-Si O vacancies are more likely to occur. Trapping of two H atoms at a close-to-Si O vacancy passivates the vacancy-induced gap states. The first H interacts with neighboring Hf atoms, whereas the second H binds to the Si atom.

Effect of Forming Gas Furnace Annealing on the Ferroelectricity and Wake-Up Effect of Hf0.5Zr0.5O2 Thin Films

“…Figure 3b summaries the leakage current density as a function of the furnace annealing temperature and ambient at ±1.5 V. Lower leakage current of FGA film at 300 °C as compared to the RTA annealed film, and lower leakage current of FGA films at any temperature as compared to the NA films (an order of magnitude) could be explained by the H-incorporation into the films. 27,[34][35][36] H-incorporation reduces leakage current by eliminating the gap states due to oxygen vacancies in the film. 34 H passivates dangling bonds due to oxygen vacancy 35 which is indirectly confirmed previously by the shift in the binding energy of the metal or oxygen ions.…”

“…27,[34][35][36] H-incorporation reduces leakage current by eliminating the gap states due to oxygen vacancies in the film. 34 H passivates dangling bonds due to oxygen vacancy 35 which is indirectly confirmed previously by the shift in the binding energy of the metal or oxygen ions. 27,35,36 Figures 4a-4d shows the endurance plot in terms of P r vs field cycles of the 56 ALD cycles HZO films before (only RTA) and after furnace annealing.…”

First-Principles Investigations on Structural, Elastic, Electronic, and Optical Properties of Tetragonal HfSiO4

“…Hafnium silicate has been fabricated by using electron beam evaporation method [22], atomic layer chemical vapor deposition [23], solid-state reaction [24], radio frequency magnetron sputtering [25], and metal-organic chemical vapor deposition [26,27]. Its fundamental properties, e.g., electrical, optical, compositional, and structural properties have been analyzed, which indicates that hafnium silicate can be considered as one of the promising candidates for high-k gate dielectric applications.…”

Nuclear reaction analysis of 1H and 2H in hafnium silicate films on Si

“…3) incorporation after preannealing in vacuum when compared to preannealing in O 2 is consistent with H incorporation in oxygen-deficient sites that are presumably eliminated during O 2 preannealing. First-principle calculations [9] support this interpretation, showing that an O vacancy near a Si atom in HfSiO tend to exothermically trap two H atoms. The reason why the HfSiO films studied here are O-deficient before O 2 annealing remains unclear, but this deficiency is probably related to the deposition process.…”

“…The presence of H in gate dielectrics, either traditional SiO 2 or novel HfSiO, is critical due to H roles in passivation and activation of defects [5][6][7][8][9]. Therefore, it is important to detect H and understand its properties in gate dielectrics.…”