Search

HfxZr1-xO2 thin films exhibit a high dielectric constant at the morphotropic phase boundary (MPB), which is beneficial for high-k dielectric applications. To minimize the equivalent oxide thickness, the effects of various HZO thicknesses and compositions on the MPB were investigated. In general, HZO films with a thickness of 10 nm exhibit a high dielectric constant owing to MPB at a composition of Hf:Zr = 3:7. However, it was confirmed that composition optimization is required for HZO films with thicknesses below 10 nm to achieve an MPB. As the HZO thickness decreases, a low Zr ratio is favorable for achieving a high dielectric constant (>45) by MPB, which is expected to be due to the large impact of the interface that consequently induces a change in phase formation. Results of electrical and x-ray diffraction analyses confirmed that a high dielectric constant was obtained when the ratio of the tetragonal phase increased and that the tetragonal phase was well formed at a low Zr ratio in the 6 nm-thick HZO film. Therefore, the optimal ratio between the tetragonal and orthorhombic phases should be determined to achieve MPB in HZO thin films, and this can be achieved by composition optimization. [ABSTRACT FROM AUTHOR]

We investigated the electronic properties of ZnO nanowire combined with the scaled high-k Al2O3 dielectrics using metal-oxide-semiconductor and field effect transistor (FET) device structures. We found that Al2O3 dielectric material can significantly reduce leakage currents when the applied voltage was restricted less than the transition voltage of direct tunneling to Fowler–Nordheim tunneling. The ZnO nanowire FETs with Al2O3 dielectrics exhibited the increase in electrical conductance, transconductance, and mobility and the threshold voltage shifted to the negative gate bias direction with decreasing Al2O3 dielectric layer thickness. [ABSTRACT FROM AUTHOR]

We investigated advanced impurity trap memory (ITM) with atomic-scale Ti impurities on LaAlO3. Our ITM showed excellent memory characteristics, including a memory window (MW) of 5 V under +12 V/-10 V, ∼44% retained charge in 10 yr retention at 85 °C, and endurance without MW degradation up to 104 cycles. To understand the origins of these enhanced characteristics, we conducted various physical analyses. Our results confirmed that the incorporation of ultrathin LaAlO3, featuring both thermodynamic stability for diffusion barrier of Ti and favorable energy band structure together with high dielectric constant for bandgap engineering of tunnel oxide, is responsible for enhanced performance. [ABSTRACT FROM AUTHOR]

Negative bias temperature instability (NBTI) in MOSFETs with high-dielectric-constant (k) gate dielectrics has been investigated using a novel pulse NBTI measurement technique. This technique enabled the separation of the contribution of interface states (Nit) from that of oxide traps (Not) to NBTI behavior by varying the measurement time (tm) and the delay time (tR). The technique was demonstrated on devices fabricated with different postdeposition annealing (PDA) conditions. It was found that, regardless of the PDA condition, the Not in high-k dielectric was more responsible for the NBTI behavior than the Nit, but the contribution of Nit to NBTI increased as the stress continued because the generation rate of Nit was higher than that of Not. [ABSTRACT FROM AUTHOR]

This study focused on the detailed understanding of the thermal stability of ruthenium oxide metal gate electrode for hafnium oxide gate dielectric. A sample with ruthenium oxide electrode shows reduction of capacitance and flatband voltage shift after high temperature annealing. The degradation of device parameter can be explained by the reduction of amorphous ruthenium oxide phase into ruthenium metallic phase and oxygen. With the introduction of an additional ruthenium metal layer between ruthenium oxide and hafnium oxide, the authors can minimize oxygen diffusion from ruthenium oxide electrode toward silicon/hafnium oxide interface which in turn improves the thermal stability of hafnium oxide devices. [ABSTRACT FROM AUTHOR]

The electrical and physical characteristics of PrTi[sub x]O[sub y], for use in metal-oxide-semiconductor gate dielectric applications were investigated. An amorphous layer of PrTi[sub x]O[sub y] with an equivalent oxide thickness of 1 nm and a dielectric constant of 23 was formed by means of e-beam evaporation. Compared to Pr[sub 2]O[sub 3], PrTi[sub x]O[sub y] was found to exhibit excellent characteristics such as a high accumulation capacitance, a low leakage current density, a thin interfacial layer, and a lower reactivity to water. The superiority of PrTi[sub x]O[sub y] can be attributed to the addition of TiO[sub 2] to the praseodymium oxide matrix. [ABSTRACT FROM AUTHOR]

The electrical and structural characteristics of an ultrathin gate dielectric, thermally grown on 4° tilted wafer has been investigated. Compared with a control wafer, a relaxation of the Si lattice strain at the SiO[sub 2]/Si(001) interface was observed for the 4° tilted wafer, which was confirmed by medium energy ion scattering spectroscopy. A significant improvement in the reliability characteristics of a metal–oxide–semiconductor (MOS) capacitor, with a 2.5-nm-thick gate oxide, grown on a tilt wafer was observed. This improvement in reliability can be explained by the relaxation of strain at the SiO[sub 2]/Si interface. An ultrathin gate dielectric grown on a tilt wafer represents a promising alternative for gate dielectric applications in future MOS devices. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

In this letter, we describe a process for the preparation of high-quality tantalum oxynitride (TaO[sub x]N[sub y]) with zirconium silicate (ZrSi[sub x]O[sub y]) as an interfacial layer for use in gate dielectric applications. Compared with conventional chemical oxide and nitride as interfacial layers, TaO[sub x]N[sub y] metal–oxide–semiconductor capacitors using ZrSi[sub x]O[sub y] as an interfacial layer exhibit lower leakage current levels at the same oxide thickness and a lower interface state density. We were able to confirm the TaO[sub x]N[sub y]/ZrSi[sub x]O[sub y] stack structure by Auger electron spectroscopy and transmission electron microscopy analyses. Zirconium silicate is a promising interfacial layer for future high-k gate dielectric applications. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This letter describes a process for the preparation of high-quality Dy-doped HfO[sub 2] for use in gate dielectric applications. Compared with conventional undoped HfO[sub 2], the HfO[sub 2] gate dielectric which contains an optimum concentration of Dy exhibits the lowest leakage current and minimum effective oxide thickness. The lower electronegativity and larger atomic radii of Dy contribute to the improvement in leakage current for Dy-doped HfO[sub 2]. The Dy-doped HfO[sub 2] is a promising gate dielectric layer for use in future high-k gate dielectric applications. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

The characteristics of atomic-layer-deposited (ALD) HfO[sub 2](30 Å)/SiO[sub 2](10 Å) stacks gate dielectrics were investigated after annealing in a deuterium (D[sub 2]) ambient. Compared with oxides annealed in a forming gas containing hydrogen (H[sub 2]), the stack dielectrics annealed in D[sub 2] ambient exhibited various advantages such as less charge trapping, less generation of interface state density (D[sub it]), a larger charge-to-breakdown (Q[sub bd]), and longer time-dependent dielectric breakdown characteristics under conditions of electrical stress. The improved reliability can be attributed to the strength of the deuterium bond. This deuterium postmetal annealing of a high-k gate dielectric has considerable potential for future use in ultralarge-scale integration device applications. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This letter presents a unique process to grow high quality ultrathin (∼60 Å) gate dielectrics using N2O (nitrous oxide) gas. Compared with conventional rapid thermally grown oxide in the O2, the new oxynitride dielectrics show very large charge-to-breakdown (at +50 mA/cm2, 850 C/cm2 for oxynitride compared to 95 C/cm2 for the control thermal oxide) and less charge trapping under constant current stress. Significantly reduced interface state generation was also observed under constant current stress and x-ray radiation. A secondary-ion mass spectroscopy depth profile indicates a nitrogen-rich layer at the Si/SiO2 interface, which can explain the improved integrity of oxynitride dielectric. [ABSTRACT FROM AUTHOR]

The electrical characteristics of ZrO[sub x]N[sub y] prepared by NH[sub 3] annealing of ZrO[sub 2] were investigated for use in metal–oxide–semiconductor gate dielectric applications. Compared with conventional ZrO[sub 2], ZrO[sub x]N[sub y] exhibits excellent electrical characteristics such as high accumulation capacitance, low leakage current density, and superior thermal stability. Based on high resolution transmission electron microscope analysis of both ZrO[sub 2] and ZrO[sub x]N[sub y] samples which had been annealed at 800 °C for 5 min, the ZrO[sub 2] exhibited a polycrystalline state but the ZrO[sub x]N[sub y] was amorphous in structure. In addition, the thickness of ZrO[sub x]N[sub y] was thinner than that of ZrO[sub 2]. The improvement in electrical characteristics can be explained by the better thermal stability and lower rate of oxidation of ZrO[sub x]N[sub y]. © 2001 American Institute of Physics. [ABSTRACT FROM AUTHOR]

This letter describes a process for the preparation of high-quality tantalum oxynitride (TaO[sub x]N[sub y]) via NH[sub 3] annealing of Ta[sub 2]O[sub 5], for use in gate dielectric applications. Compared with tantalum oxide (Ta[sub 2]O[sub 5]), a significant improvement in the dielectric constant was obtained by the NH[sub 3] treatment. In addition, light reoxidation in a wet ambient at 450 °C resulted in a significantly reduced leakage current. We confirmed nitrogen incorporation in the tantalum oxynitride (TaO[sub x]N[sub y]) by Auger electron spectroscopy. By optimizing the nitridation and reoxidation processes, we obtained an equivalent oxide thickness as thin as 1.6 nm and a leakage current of less than 10 mA/cm2 at -1.5 V. © 2000 American Institute of Physics. [ABSTRACT FROM AUTHOR]