Thermal stability of (HfO2)x(Al2O3)1−x on Si

Abstract

The kinetics of the interfacial layer (IL) growth between Hf aluminates and the Si substrate during high-temperature rapid thermal annealing (RTA) in either N2 (∼10 Torr) or high vacuum (∼2×10−5 Torr) is studied by high-resolution x-ray photoelectron spectroscopy and cross-sectional transmission electron microscopy. The significant difference of the IL growth observed between high vacuum and relatively oxygen-rich N2 annealing (both at 1000 °C) is shown to be caused by the oxygen species from the annealing ambient. Our results also show that Hf aluminates exhibit much stronger resistance to oxygen diffusion than pure HfO2 during RTA in N2 ambient, and the resistance becomes stronger with more Al incorporated into HfO2. This observation is explained by the combined effects of (i) smaller oxygen diffusion coefficient of Al2O3 than HfO2, and (ii) higher crystallization temperature of the Hf aluminates.

The physical and electrical characterizations of Cr-doped BiFeO3 ferroelectric thin films for nonvolatile memory applications

“…1(b) shows the interface between the HfO 2 insulator and silicon surface. The thickness of the interfacial layer (IL) is about 3 nm, which is close to the literature results of 3.7 nm [26] and 3.1 nm [27] for pure HfO 2 deposited on silicon substrate by the method of atomic layer deposition (ALD). In addition, since the dielectric constant of high-k materials is higher than that of conventional SiO 2 , the voltage drop across the ferroelectric layer of ferroelectric/high-k stack structure becomes large according to the coupling ratio of capacitance for two dielectric films in serial [28].…”

Low Leakage Current Transport and High Breakdown Strength of Pulsed Laser Deposited HfO2/SiC Metal-Insulator-Semiconductor Device Structures

“…23 The formation of SiO 2 seems to be dependent on the deposition process as observed in the ALD technique, where there is a distinct peak appearing at $103 eV. 24,25 The C-V measurements, as shown in Fig. 4, were carried out for the MIS devices in a frequency range of 10-400 MHz.…”

Effect of Al addition on the microstructure and electronic structure of HfO2 film

“…[1][2][3] Hf-based materials appear to be among the most promising candidates due to their large dielectric constant ͑ ͒, which ensures satisfactory device performance at much larger dielectric thickness compared to that of SiO 2 , thus solving the problem of large leakage current originating from electron tunneling. Compared to pure HfO 2 , the addition of Al is found to increase the Si/ dielectric interfacial stability 4,5 and the crystallization temperature of the material. 6,7 It is also expected that Al addition will enlarge the band gap of HfO 2 .…”