共查询到20条相似文献,搜索用时 15 毫秒
1.
P. Darmawan 《Solid State Communications》2006,138(12):571-573
Amorphous Lu2O3 high-k gate dielectrics were grown directly on n-type (100) Si substrates by the pulsed laser deposition (PLD) technique. High-resolution transmission electron microscope (HRTEM) observation illustrated that the Lu2O3 film has amorphous structure and the interface with Si substrate is free from amorphous SiO2. An equivalent oxide thickness (EOT) of 1.1 nm with a leakage current density of 2.6×10−5 A/cm2 at 1 V accumulation bias was obtained for 4.5 nm thick Lu2O3 thin film deposited at room temperature followed by post-deposition anneal (PDA) at 600 °C in oxygen ambient. The effects of PDA process and light illumination were studied by capacitance-voltage (C-V) and current density-voltage (J-V) measurements. It was proposed that the net fixed charge density and leakage current density could be altered significantly depending on the post-annealing conditions and the capability of traps to trap and release charges. 相似文献
2.
K. Kakushima K. Okamoto K. Tachi S. Sato P. Ahmet N. Sugii H. Iwai 《Applied Surface Science》2008,254(19):6106-6108
The flat band voltage shifts of HfO2/SiO2/nSi capacitors with ultra-thin La2O3 insertion at HfO2/SiO2 interface have been confirmed using hard X-ray photoelectron spectroscopy (HX-PES). By increasing the amount of La2O3 insertion, the binding energy of Si 1s core spectra increases, which means that the surface potential of Si substrate also increases. A voltage drop difference of HfO2 and La2O3 at SiO2 interface can be estimated to be 0.40 V. 相似文献
3.
L. Shi 《Applied Surface Science》2007,253(7):3731-3735
As a potential gate dielectric material, the La2O3 doped SiO2 (LSO, the mole ratio is about 1:5) films were fabricated on n-Si (0 0 1) substrates by using pulsed laser deposition technique. By virtue of several measurements, the microstructure and electrical properties of the LSO films were characterized. The LSO films keep the amorphous state up to a high annealing temperature of 800 °C. From HRTEM and XPS results, these La atoms of the LSO films do not react with silicon substrate to form any La-compound at interfacial layer. However, these O atoms of the LSO films diffuse from the film toward the silicon substrate so as to form a SiO2 interfacial layer. The thickness of SiO2 layer is only about two atomic layers. A possible explanation for interfacial reaction has been proposed. The scanning electron microscope image shows the surface of the amorphous LSO film very flat. The LSO film shows a dielectric constant of 12.8 at 1 MHz. For the LSO film with thickness of 3 nm, a small equivalent oxide thickness of 1.2 nm is obtained. The leakage current density of the LSO film is 1.54 × 10−4 A/cm2 at a gate bias voltage of 1 V. 相似文献
4.
Sonalee ChopraSeema Sharma T.C. Goel R.G. Mendiratta 《Solid State Communications》2003,127(4):299-304
Thin films of Pb1−xCaxTiO3 [x=0.20, 0.24 and 0.28] have been prepared on ITO coated Corning glass substrates by sol gel technique. The perovskite phase of PCT films is formed at 650 °C with a polycrystalline tetragonal structure. The tetragonal factor (c/a) decreases with increasing Ca concentration. Dielectric, pyroelectric and ferroelectric studies have been carried out on these films. The effects of introduction of Ca ion in PbTiO3 have also been discussed. 相似文献
5.
Hafnium oxynitride (HfOxNy) gate dielectric has been deposited on Si (1 0 0) by means of radio frequency (rf) reactive sputtering using directly a HfO2 target in N2/Ar ambient. The thermal stability and microstructural characteristics for the HfOxNy films have been investigated. XPS results confirmed that nitrogen was successfully incorporated into the HfO2 films. XRD analyses showed that the HfOxNy films remain amorphous after 800 °C annealing in N2 ambient. Meanwhile the HfOxNy films can also effectively suppress oxygen diffusion during high temperature annealing and prevent interface layer from forming between HfOxNy films and Si substrates. AFM measurements demonstrated that surface roughness of the HfOxNy films increase slightly as compared to those pure HfO2 films after post deposition annealing. By virtue of building reasonable model structure, the optical properties of the HfOxNy films have been discussed in detail. 相似文献
6.
Sandwich-structure Al2O3/HfO2/Al2O3 gate dielectric films were grown on ultra-thin silicon-on-insulator (SOI) substrates by vacuum electron beam evaporation (EB-PVD) method. AFM and TEM observations showed that the films remained amorphous even after post-annealing treatment at 950 °C with smooth surface and clean silicon interface. EDX- and XPS-analysis results revealed no silicate or silicide at the silicon interface. The equivalent oxide thickness was 3 nm and the dielectric constant was around 7.2, as determined by electrical measurements. A fixed charge density of 3 × 1010 cm−2 and a leakage current of 5 × 10−7A/cm2 at 2 V gate bias were achieved for Au/gate stack /Si/SiO2/Si/Au MIS capacitors. Post-annealing treatment was found to effectively reduce trap density, but increase in annealing temperature did not made any significant difference in the electrical performance. 相似文献
7.
Ningli AnHongzhong Liu Yucheng DingMin Zhang Yiping Tang 《Applied Surface Science》2011,257(9):3831-3835
In the present study, poly(vinylidene fluoride) (PVDF)/nano-TiO2 electroactive film was prepared by coating a substrate with an acetone/DMF solution, which was evaporated at a high temperature (110 °C). The crystallisation behaviour, dynamic mechanical properties and electroactive properties of this PVDF/nano-TiO2 electroactive film were investigated. The cross-section and surface of the film were observed with a scanning electron microscope (SEM). X-ray diffraction (XRD) results showed that the film containing the PVDF β phase, the desired ferroelectric phase, was obtained by crystallising the mixed solution of nano-TiO2 and PVDF at 110 °C, while the film containing the α phase was obtained from the crystallisation of the pure PVDF solution at the same temperature. It was found that the storage modulus, the room-temperature dielectric constant and the electric breakdown strength of the composite films were much higher than those of a pure PVDF film. TiO2 improved the mechanical properties and electroactive properties of the film. The results indicate that PVDF/nano-TiO2 composite films can be applied to the fabrication of self-sensing actuator devices. 相似文献
8.
The growth and properties of gadolinium oxide (Gd2O3) films prepared by anodic oxidation were investigated. Uniform Gd2O3 thin film with good oxide quality was obtained. The X-ray diffraction (XRD) pattern of the Gd2O3 films showed that they had a poly-crystalline structure. The dielectric constants of Gd2O3 films oxidized at 30 and 60 V are 9.4 and 12.2, respectively. The equivalent oxide thickness (EOT) of the Gd2O3 stacked oxide is in the range of 5.8-9.4 nm. The MOS capacitor with Gd2O3 exhibits interesting electrical properties. Longer oxidation time reduced the leakage current density for 30 V anodic oxidation but increased the leakage current density for 60 V anodic oxidation. This work reveals that Gd2O3 could also be an alternative dielectric for Si substrate and therefore, might pave the way to fabricate CMOS devices in the future. 相似文献
9.
High-k HfO2-Al2O3 composite gate dielectric thin films on Si(1 0 0) have been deposited by means of magnetron sputtering. The microstructure and interfacial characteristics of the HfO2-Al2O3 films have been investigated by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and spectroscopic ellipsometry (SE). Analysis by XRD has confirmed that an amorphous structure of the HfO2-Al2O3 composite films is maintained up to an annealing temperature of 800 °C, which is much higher than that of pure HfO2 thin films. FTIR characterization indicates that the growth of the interfacial SiO2 layer is effectively suppressed when the annealing temperature is as low as 800 °C, which is also confirmed by spectroscopy ellipsometry measurement. These results clearly show that the crystallization temperature of the nanolaminate HfO2-Al2O3 composite films has been increased compared to pure HfO2 films. Al2O3 as a passivation barrier for HfO2 high-k dielectrics prevents oxygen diffusion and the interfacial layer growth effectively. 相似文献
10.
The composition and microstructure of rf sputtered 20 nm Ta2O5 on N2O or NH3 Rapid Thermal Nitrided (RTN) Si substrates have been investigated by X-ray photoelectron spectroscopy. RTN at 800 and 850 °C is effective to suppress active oxidation of Si. There is no evidence for the presence of SiO2 at Si interface. A lightly nitrided surface is established in both cases without a formation of detectable oxynitride layer at Si. A layered nature of the films is observed, with stoichiometric tantalum pentoxide at and close to the films’ surface. In the depth, the films are mixed ones whose composition depends on the nitridation ambient. N2O treatment stimulates oxidation processes during the film deposition while NH3 nitridation results to a less effective oxidation and produces Ta-silicate like film. The correlation between the composition of the interfacial regions and the nitridation gas is also discussed. The results suggest that hydrogen, as a component of nitridation ambient, plays significant role in the reactions controlling the exact composition of the deposited Ta2O5, activating reactions with nitrogen. Nitrogen related reactions likely occur with NH3 processing but do not with N2O one. The presence of nitrogen feature is not detected in N2O-samples spectra at all. In the integration perspective, preliminary RTN of Si in N2O or NH3 could be a suitable way to produce layered Ta2O5-based films with more or less presence of tantalum silicate with a trace of nitrogen, either only at the interface with Si (N2O-process) or in the whole film (NH3-process). 相似文献
11.
In this paper, we report and analyze the large blue shift in the optical band-gap of sol-gel derived Ba0.5Sr0.5TiO3 (BST) thin films. BST films of different thickness (150 nm, 320 nm and 480 nm respectively) were deposited layer by layer onto fused quartz substrates by a spin coating technique. The drying temperature for individual layers (pre-sintering temperature) was varied as 400, 500 and 600 °C. A large blue shift in the band-gap was observed (with a value 4.70 eV compared to the bulk value of 3.60 eV) for films pre-sintered at 400 °C, which decreased with increase in the pre-sintering temperature. To date such blue shifts have been attributed to grain size reduction, stress and the amorphous nature of the films. Here, the blue shift has been correlated with the presence of charge carriers generated by oxygen vacancies and explained on the basis of the Burstein-Moss effect. 相似文献
12.
The surface reaction mechanism of Y2O3 atomic layer deposition (ALD) on the hydroxylated silicon surface is investigated by using density functional theory. The ALD process is designed into two half-reactions, i.e., Cp3Y (Cp = cyclopentadienyl) and H2O half-reactions. For the Cp3Y half-reaction, the chemisorbed complex is formed along with the change of metal-Cp bonding from Y-C(π) to Y-C1(σ). For the H2O half-reactions, the chemisorbed energies are increased with the relief of steric congestion around yttrium metal center. In addition, Gibbs free energy calculations show that it is thermodynamically favorable for the Cp3Y half-reactions. By comparing with the reaction of H2O with {Si}-(O2)YCp, it is thermodynamically more favorable and kinetically less favorable for the reactions of H2O with {Si}-OYCp2 as well as with {Si}-OYCp(OH). 相似文献
13.
Zr-Ti and Hf-Ti composite nitrates were successfully developed as single-source precursors for the chemical vapor deposition (CVD) of ZrxTi1−xO2 and HfxTi1−xO2 thin films. The Zr-Ti nitrate can be assumed as a solid solution of the individual Zr and Ti nitrates, and the Zr/Ti molar ratio in the deposited ZrxTi1−xO2 films is consistent with that in the precursor. The Hf-Ti nitrate appears to be a mixture of the Hf and Ti nitrates and the composition of the deposited HfxTi1−xO2 films depends remarkably on the heating time of precursor. Both ZrxTi1−xO2 and HfxTi1−xO2 films exhibit trade-off properties between band gap and dielectric constant. The obtained results suggest that ZrxTi1−xO2 and HfxTi1−xO2 films are promising candidates for gate dielectric application to improve the scalability and reduce the leakage current of the future complementary metal-oxide-semiconductor (CMOS) devices. 相似文献
14.
Charge trapping characteristics of the metal-insulator-silicon (MIS) capacitors with Si02/HfO2//A12O3 stacked dielectrics are investigated for memory applications'. A capacitance-voltage hysteresis memory window as large as 7.3 V is achieved for the gate voltage sweeping of ±12 V, and a fiat-band voltage shift of 1.5 V is observed in terms of programming under 5 V and I ms. Furthermore, the time- and voltage-dependent charge trapping characteristics are also demonstrated, the former is related to charge trapping saturation and the latter is ascribed to variable tunnelling barriers for electron injecting and discharging under different voltages. 相似文献
15.
Ba0.6Sr0.4TiO3 thin films were deposited on Pt/SiO2/Si substrate by radio frequency magnetron sputtering. High-resolution transmission electron microscopy (HRTEM) observation shows that there is a transition layer at BST/Pt interface, and the layer is about 7-8 nm thickness. It is found that the transition layer was diminished to about 2-3 nm thickness by reducing the initial RF sputtering power. X-ray photoelectron spectroscopy (XPS) depth profiles show that high Ti atomic concentration results in a thick interfacial transition layer. Moreover, the symmetry ν of ?r-V curve of BST thin film is enhanced from 52.37 to 95.98%. Meanwhile, the tunability, difference of negative and positive remanent polarization (Pr), and that of coercive field (EC) are remarkably improved. 相似文献
16.
Band bending and band alignment at HfO2/SiO2/Si and HfO2/Hf/SiO2/Si interfaces were investigated using X-ray photoelectron spectroscopy. After Hf-metal pre-deposition, a 0.55 eV band bending in Si and a 1.80 eV binding energy decrease for Hf 4f and O 1s of HfO2 were observed. This was attributed to the introduction of negative space charges at interface by Hf pre-deposition. Band bending decrease and synchronous binding energy increases of O 1s and Hf 4f for HfO2 were observed during initial Ar+ sputtering of the Hf pre-deposited sample. This was interpreted through the neutralization of negative space charges by sputtering-induced oxygen vacancies. 相似文献
17.
Byoungjun Park 《Applied Surface Science》2008,254(23):7905-7908
The electrical characteristics of polycrystalline Si (poly Si) layers embedded into high-k Al2O3 (alumina) gate layers are investigated in this work. The capacitance versus voltage (C-V) curves obtained from the metal-alumina-polysilicon-alumina-silicon (MASAS) capacitors exhibit significant threshold voltage shifts, and the width of their hysteresis window is dependent on the range of the voltage sweep. The counterclockwise hysteresis observed in the C-V curves indicates that electrons originating from the p-type Si substrate in the inversion condition are trapped in the floating gate layer consisting of the poly Si layer present between the top and bottom Al2O3 layers in the MASAS capacitor. Also, current versus voltage (I-V) measurements are performed to examine the electrical characteristics of the fabricated capacitors. The I-V measurements reveal that our MASAS capacitors show a very low leakage current density, compared to the previously reported results. 相似文献
18.
Metallo-organic decomposition derived dielectric thin films of calcium zirconate doped with various concentrations of strontium ((Ca, Sr)ZrO3) were prepared on Pt coated silicon substrate. Mainly in this paper, we present the investigations of their structural developments and present their electric and dielectric properties as well. The structural developments show that the CaZrO3 film has amorphous structure with carbonate existing when annealed at 600 °C, while annealed at 650 °C and above, the carbonate is decomposed and those films crystallize into perovskite phase without preferred orientation. In addition, the prepared (Ca, Sr)ZrO3 films with their Zr-O bonds affected by strontium doping are homogenous and stable as solid solutions in any concentration of strontium and all Bragg diffraction characteristics for the films shift downward with the increase in the concentration of strontium. Moreover, the electric properties show that the (Ca, Sr)ZrO3 films have very low leakage current density and high breakdown strength; typically, the CaZrO3 film annealed at 650 °C has the leakage current density approximately 9.5 × 10−8 A cm−2 in the field strength of 2.6 MV cm−1. Furthermore, the dielectric properties show that their dielectric constants are higher than 12.8 with very little dispersion in the frequency range from 100 Hz to 1 MHz and are independent of applied dc bias as well. The dielectric properties, in combination with the electric properties, make the materials promising candidates for high-voltage and high-reliability capacitor applications. 相似文献
19.
Hiroaki Arimura Shinya Horie Takashi Minami Motomu Kosuda Takayoshi Shimura 《Applied Surface Science》2008,254(19):6119-6122
We investigated the optimum structure for Ti-containing Hf-based high-k gate dielectrics to achieve EOT scaling below 1 nm. TiO2/HfSiO/SiO2 trilayer and HfTiSiO/SiO2 bilayer structures were fabricated by a newly developed in-situ PVD-based method. We found that thermal diffusion of Ti atoms to SiO2 underlayers degrades the EOT-Jg characteristics. Our results clearly demonstrated the impact of the trilayered structure with TiO2 capping for improving EOT-Jg characteristics of the gate stack. We achieved an EOT scaling of 0.78 nm as well as reduced gate leakage of 7.2 × 10−2 A/cm2 for a TiO2/HfSiO/SiO2 trilayered high-k dielectric while maintaining the electrical properties at the bottom interface. 相似文献
20.
C. Zhu 《Physics letters. A》2007,372(1):81-86
Using Landau-Devonshire (LD)-type phenomenological model, we investigate the phase diagrams and dielectric behaviors of single-domain single-crystal Ba0.6Sr0.4TiO3 films deposited on orthorhombic substrates. An anisotropic strain factor is introduced to quantitatively calculate the effects of anisotropic in-plane misfit strains. Investigation indicates that anisotropic strains play a crucial role on formation of stable ferroelectric phases and dielectric properties. The anisotropic strains induce tetragonal phases which only contain one in-plane spontaneous polarization component. These phases do not exist in BST films of the same composition under isotropic strains. Moreover, permittivity and tunability of films can reach to maximum when the corresponding spontaneous polarization component disappears at the boundaries of structural phase transition. 相似文献