A 2 O 3 films were deposited by atomic layer deposition (ALD) using trimethylaluminum and O 3 as precursor and oxidant, respectively, at growth temperatures ranging from room temperature to 300°C on Si(100) substrates. Growth rate and refractive index of the Al 2 O 3 films decreased from 0.20 to 0.08 nm/cycle and increased from 1.52 to 1.65, respectively, with increasing growth temperature. The dielectric constant slightly increased from 6.8 to 8 with increasing growth temperature in the same temperature range. Al 2 O 3 films grown using O 3 as oxidant show a smaller hysteresis, lower leakage current density, and higher breakdown field strength compared to those using H 2 O as oxidant at the same growth temperature. X-ray photoelectron spectroscopy showed that the films grown at lower temperatures have a smaller bandgap energy. The Al 2 O 3 films grown at a temperature as low as 100°C showed reasonable dielectric properties for dielectric film applications on flexible substrates.

https://iopscience.iop.org/article/10.1149/1.2177047/pdf

Low Temperature ( < 100 ° C ) Deposition of Aluminum Oxide Thin Films by ALD with O3 as Oxidant

https://hal.archives-ouvertes.fr/hal-02396239/document

Investigation of the initial deposition steps and the interfacial layer of Atomic Layer Deposited (ALD) Al2O3 on Si

The presence of an ultrathin oxide layer at the high-k/SiO2 interface may result in an interfacial dipole related to the specific high-k dielectric used for the gate stacks. 1 nm HfO2/x nmAl2O3/SiO2/Si stacks with different x values (x=0, 0.4, 0.8, 1.2) have been prepared by atomic layer deposition. Using photoelectron spectroscopy, an Al-related interfacial dipole in the HfO2/Al2O3/SiO2 gate stack has been identified. X-ray photoelectron spectroscopy analysis shows that the dipole is correlated with the formation of an interfacial Al-silicate. The dipole is located at the Al-silicate interface between Al2O3 and SiO2, and its strength increases with the increase in Al2O3 thickness because of Al silicate growth. Such Al-related interfacial dipole should have potential applications in future positive metal-oxide-semiconductor devices.

X-ray photoelectron spectroscopy and ultraviolet photoelectron spectroscopy investigation of Al-related dipole at the HfO2/Si interface

Interfacial layer (IL) suppression is a big concern in atomic layer deposition (ALD) of high-k gate dielectrics. We have studied two kinds of surface pretreatments for ALD Al2O3 deposition: surface Al(CH3)3 (TMA) pretreatment (ST) and surface nitridation (SN). High resolution transmission electron microscopy images show that the IL has been effectively suppressed after performing surface pretreatments. X-ray photoelectron spectroscopy results indicate that both surface pretreatments are beneficial for compact Al2O3 deposition, however, the sample with SN shows much better interface thermal stability. And electrical characterizations demonstrate that the capacitor with SN exhibits better interface property, lower leakage current, and smaller capacitance-voltage (C-V) hysteresis. Based on transient capacitance measurement (C-t) and C-V measurement with different gate bias sweep ranges, a “shallow level trap” model is proposed to explain well the difference of C-V hysteresis between ST and SN.

Spectroscopic and electrical properties of atomic layer deposition Al2O3 gate dielectric on surface pretreated Si substrate

The influence of the ozone concentration (150–370g∕m3) during the atomic layer deposition of HfO2 gate dielectrics on the dielectric performance of the films and the device performance of metal-oxide-semiconductor field effect transistor (MOSFET) grown on Si was studied. The use of a lower ozone concentration (150g∕m3) produced a HfO2 film with a stoichiometric oxygen concentration, whereas a higher ozone concentration (390g∕m3) produced an oxygen excess HfO2 film. An almost identical Dit to that of the SiO2 gate dielectric film was obtained from the stoichiometric HfO2, whereas the oxygen excess HfO2 gate dielectric produced a much higher Dit with the polycrystalline-Si electrode. The investigation of the interface states using x-ray photoelectron spectroscopy revealed that the excessive oxygen incorporated during the film growth made the interfacial reaction and oxidation serious. This increased the interface trap density and degraded the interface properties. Accordingly, an electron effective mobility...

Influence of the oxygen concentration of atomic-layer-deposited HfO2 gate dielectric films on the electron mobility of polycrystalline-Si gate transistors

We investigated a depth profile of the chemical states of an Al2O3/Si interface using nondestructive photon energy-dependent high-resolution x-ray photoelectron spectroscopy (HRXPS). The Si 2p binding energy, attributed to the oxide interfacial layer (OIL), was found to shift from 102.1 eV to 102.9 eV as the OIL region closer to Al2O3 layer was sampled, while the Al 2p binding energy remains the same. This fact strongly suggests that the chemical state of the interfacial layer is not Al silicate as previously believed. We instead propose from the HRXPS of Al 2p and Si 2p depth-profile studies that the chemical states of the Al2O3/Si interface mainly consist of SiO2 and Si2O3.

S.-J. Oh

Papers

Nondestructive depth profile of the chemical state of ultrathin Al2O3/Si interface