Thermal phase separation of ZrSiO₄thin films and frequency- dependent electrical characteristics of the Al/ZrSiO₄/p-Si/Al MOS capacitors

Abstract

In this work, the thermal phase separation and annealing optimization of ZrSiO 4 thin films have been carried out. Following annealing optimization, the frequency-dependent electrical characteristics of the Al/ZrSiO 4 /p-Si/Al MOS capacitors were investigated in detail. The chemical evolution of the films under various annealing temperatures was determined by Fourier transform infrared spectroscopy (FTIR) measurements. The phase separation was determined by x-ray diffraction (XRD) measurements. The electrical parameters were determined via the capacitance-voltage (C-V ), conductance-voltage (G/ω) and leakage-current-voltage (I g -V g ).The results demonstrate that zirconium silicate formations are present at 1000 °C annealing with the SiO 2 interfacial layer. The film was in amorphous form after annealing at 250 °C. The tetragonal phases of ZrO 2 were obtained after annealing at 500 °C. When the temperature approaches 750 °C, transitions from the tetragonal phase to the monoclinic phase were observed. The obtained XRD peaks after 1000 °C annealing matched the crystalline peaks of ZrSiO 4 . This means that the crystalline zirconium dioxide in the structure has been converted into a crystalline silicate phase. The interface states increased to 5.71×10 10 and the number of border traps decreased to 7.18×10 10 cm −2 with the increasing temperature. These results indicate that an excellent ZrSiO4/Si interface has been fabricated. The order of the leakage current varied from 10 −9 Acm −2 to 10 −6 Acm −2 . The MOS capacitor fabricated with the films annealed at 1000 °C shows better behavior in terms of its structural, chemical and electrical properties. Hence, detailed frequency-dependent electrical characteristics were performed for the ZrSiO 4 thin film annealed at 1000 °C. Very slight capacitance variations were observed under the frequency variations. This shows that the density of frequency-dependent charges is very low at the ZrSiO 4 /Si interface. The barrier height of the device varies slightly from 0.776 eV to 0.827 eV under frequency dispersion. Briefly, it is concluded that the devices annealed at 1000 °C exhibit promising electrical characteristics.

Damage Effect of ALD-Al2O3 Based Metal-Oxide-Semiconductor Structures under Gamma-Ray Irradiation

“…The effective trapping efficiencies in 14 1. nm Al 2 O 3 are 7.7%, 8.5% and 10.7% under 1.2 Mrad(Si) (approximately 0.69 Mrad(SiO 2 )), 2.5 Mrad(Si)(approximately 1.45 Mrad(SiO 2 )) and 4 Mrad(Si)(approximately 2.32 Mrad(SiO 2 )), respectively.…”

“…In advanced MOS devices, SiO 2 , which is widely used as the gate material in traditional MOS devices, is not applicable anymore as the leakage current and static power consumption would increase dramatically when the thickness of SiO 2 decreases to lower than 2 nm, which would seriously impact the properties of MOS devices. Alternative materials with higher permittivity which can be called high-k materials have been proposed to replace SiO 2 as the gate dielectric such as HfO 2 , Al 2 O 3 , ZrO 2 , La 2 O 3 [1,2]. High-k materials that can be used as the gate dielectric in MOS devices must have a relatively larger bandgap to ensure large enough conduction band offset and valence band offset between the gate dielectric and the semiconductor substrate, which can restrict the charge transport and then reduce the leakage current of the device.…”

“…The radiation effect of Al 2 O 3 based MOS devices has been studied by many research groups from the aspects of radiation induced charge trapping, trap characteristics and leakage current characteristics and so on. The charge trapping and passivation properties of Al 2 O 3 based stack gate dielectric under gamma-ray irradiation was studied by using Capacitance-Voltage and Deep-Level Transient Spectroscopy measurements in [1,11,12]. The radiation induced defect characteristic as well as the leakage current in Al 2 O 3 based metal-semiconductor-oxide structures under Si heavy ion were studied in [13].…”