Oxide Dielectric Films Research Articles

Optical characteristics of pore size on porous anodic aluminium oxide films with embedded silver nanoparticles

Dielectric porous anodic aluminum oxide films embedded with two-dimensional silver nanoparticles arrays (porous Ag/AAO) have been fabricated by electrochemical anodization and deposition, wherein the position and rate of the Ag nanoparticles within the nanopores can be properly controlled. These porous Ag/AAO films have photo-induced plasmonic coupling and can be applied toward photo-absorption sensors. The plasmonic absorption is clearly visible and its absorption maximum red-shifts with increasing particle diameters. An investigation of how the absorption spectrum is influenced by systematically changing the pore diameter and inter-pore spacing is laid out. This work provides an approach to precisely tune the peak wavelength and the bandwidth of plasmonic absorption of porous Ag/AAO films utilizing fine control of the pore diameters. The wavelength shift slope of absorption peak with the pore diameter is measured to be approximately 0.82nm/nm (peak wavelength/pore diameter). These tuning curves may be useful in the design of photon-response sensors and 2D tunable plasmonic-based nanostructure is expected to enable applications such as tunable photon-induced electrical conductivity.

Organic diamond disk versus brazed diamond disk for dressing a chemical–mechanical polishing pad

Diamond pad conditioners can be used to determine the efficiency of chemical–mechanical polishing (CMP) processes and the quality of polished wafers. Conventional diamond conditioners such as brazed diamond disks (BDDs) consist of braze-bonded diamond grits. Although conventional diamond conditioners consist of regularly distributed diamond grits, the grit tips are not leveled to the same height. In this research, we evaluated diamond conditioners manufactured using polymer-bonded diamond grits for use in CMP; these conditioners are known as organic diamond disks (ODDs). ODDs are fabricated by reverse casting the substrate. Instead of using a flat substrate as the backing for attaching diamond grits, the substrate is prepared after the diamond grits are leveled on the surface of a mold. The ODD and the BDD were fabricated as circular dressing disks and used in the CMP of dielectric oxide films. Diamond leveling (height distribution of the diamond grits) for the BDD is found to be greater than 50μm. The diamond tips of the ODD are leveled to less than 15μm. The results show that the ODD-dressed pads produce fewer defects in wafers than the BDD-dressed ones. Although the pad dressing rate is lower for the ODD, the wafer removal rate for the ODD is higher than that for the BDD. Hence, the use of ODDs for the mass production of semiconductors can increase not only the lifespan of both the disks and the pads but also the throughput of wafers produced during CMP. Finally, the ODD is processed at room temperature to prevent thermal degradation of its diamond grits.

Room temperature fabricated transparent amorphous indium zinc oxide based thin film transistor using high-κ HfO2 as gate insulator

We report here the performance of amorphous oxide transparent thin film transistors (TFTs) fabricated using DC magnetron sputter techniques at room temperature. Amorphous indium zinc oxide (a-IZO, In2O3:ZnO, 90:10wt.%) and high dielectric constant hafnium oxide (HfO2) films were deposited for the semiconducting channel and gate insulator under a mixture of ambient argon and oxygen gas, respectively. The reported transparent TFT structure was a bottom-gate type, consisting of indium-tin-oxide and aluminium as gate electrode and source/drain electrodes, respectively. The optical transmittance of a-IZO films in the visible region was greater than 84%. The a-IZO TFTs showed that the field effect saturation mobility, Ion/Ioff ratio, sub-threshold swing, and threshold voltage were extracted to give 13.09cm2/V-s, 4×105, 0.42V/decade, and 3.54V, respectively. The reported a-IZO TFT with high dielectric constant HfO2 gate dielectric sputtered at room temperature presents high quality characteristics, which can be used as good candidate for the application of low-temperature fabricated optoelectronic devices on organic flexible substrates.

Properties of transparent yttrium oxide dielectric films prepared by sol–gel process

In this research, yttrium oxide (Y 2O 3) gate dielectric films were deposited onto alkali-free glass substrates by a sol–gel process. This report describes the effects of annealing temperatures on the microstructural and electrical properties of sol–gel derived Y 2O 3 films. These sol–gel films were preheated at 300 °C for 10 min, and then annealed at 400–550 °C for 1 h. XRD results revealed that all annealed films exhibited preferential (2 2 2) orientation; films annealed at 450–550 °C were polycrystalline with cubic structures. The average transmittances of polycrystalline Y 2O 3 films were over 88.0% in the visible range. The electrical properties of the Y 2O 3 films were analyzed by capacitance–voltage ( C– V) and current–voltage ( I– V) measurements. Films annealed at 500 °C yielded the lowest leakage current density, 1.8 × 10 −7 A/cm 2, at an applied voltage of 5 V, and had a dielectric constant of 10.0 at 100 kHz.

Suppressing methods of cracking on inter-metallic silicon oxide films

We investigated the mechanism of cracking between the inter/intra-metallic dielectric (IMD) silicon oxide films after anneal process. The cracks were initiated at the top corner of aluminum lines, then propagated through the silicon oxide films. Thus, the extrusion of melted Al along the IMD cracks, caused metal line bridge. These cracking conditions involve the stresses of the IMD films as well as their thickness. Namely, the cracking was suppressed not only by decreasing the magnitude of compressive stress but also increasing the film thickness on silicon oxide films. These results are in accordance with the finite element method stress analysis using silicon oxide film stress and thickness. In this paper, we focused on the analysis of crack formation mechanism on the IMD film, and finally proposed an empirical criterion for crack-safety condition.

Improvement on low-temperature deposited HfO 2 film and interfacial layer by high-pressure oxygen treatment

In this study, high-pressure oxygen (O 2 and O 2 + UV light) technologies were employed to effectively improve the properties of low-temperature-deposited metal oxide dielectric films and interfacial layer. In this work, 13 nm HfO 2 thin films were deposited by sputtering method at room temperature. Then, the oxygen treatments with a high-pressure of 1500 psi at 150 °C were performed to replace the conventional high temperature annealing. According to the XPS analyses, integration area of the absorption peaks of O–Hf and O–Hf–Si bonding energies apparently raise and the quantity of oxygen in deposited thin films also increases from XPS measurement. In addition, the leakage current density of standard HfO 2 film after O 2 and O 2 + UV light treatments can be improved from 3.12 × 10 −6 A/cm 2 to 6.27 × 10 −7 and 1.3 × 10 −8 A/cm 2 at |Vg| = 3 V. The proposed low-temperature and high pressure O 2 or O 2 + UV light treatment for improving high- k dielectric films is applicable for the future flexible electronics.

Effect of deposition temperature on the properties of CeO 2 films grown by atomic layer deposition

Cerium oxide dielectric thin films have been grown on n-type silicon by atomic layer deposition using a monomeric homoleptic Ce IV alkoxide precursor with water vapour. Herein we report the dielectric properties of CeO 2 films deposited from tetrakis(1-methoxy-2-methyl-2-propanolate)cerium. The resulting films exhibit permittivities in the range 25–42 at 1 MHz with a strong dependency on the deposition temperature. The microstructural origin of this behaviour has been investigated. The as-deposited films were found to be crystalline and they exhibited the cubic fluorite structure for deposition temperatures in the range 150 °C to 350 °C. Variations in the crystallite sizes are governed by the deposition temperature and have been estimated using a Debye–Scherrer analysis of the X-ray diffraction patterns. The changing crystallite size correlates with changes seen in the triply-degenerate F 2g first-order Raman line half-width at 465 cm − 1 . It is concluded that the frequency dependency of the film dielectric properties is strongly influenced by the crystallite size which in turn is governed by the growth temperature.

초음파를 이용한 전처리가 알루미늄의 전기화학적 에칭 및 정전용량에 미치는 효과

Aluminum was electrochemically etched in acid solution and the surface area was magnified by the formation of etch pits. Etched aluminum was covered with a compact and dense dielectric oxide film by anodization and applied to the aluminum electrolytic capacitor electrode. Capacitance of aluminum electrolytic capacitor is closely related with surface area, which depends on size and number of etch pits. Size of etch pits need to be controlled because inside of the pits can be buried by the formation of dielectric oxide film. In this work, the effect of ultrasound pretreatment on the aluminum etch pit formation and capacitance were investigated. Additionally, the relationship between the second etching effect on pit size and capacitance was studied.

Optical properties and thermal stability of LaYbO3 ternary oxide for high-k dielectric application

A new ternary rare oxide dielectric LaYbO3 film had been prepared on silicon wafers and quartz substrates by reactive sputtering method using a La–Yb metal target. A range of analysis techniques was performed to determine the optical band gap, thermal stability, and electrical property of the deposited samples. It was found the band gap of LaYbO3 film was about 5.8eV. And the crystallization temperature for rapid thermal annealing (20s) was between 900 and 950°C. X-ray photoelectron spectroscopy results indicate the formation of the SiO2 and silicate in the interface between silicon wafer and LaYbO3 film. The dielectric constant is about 23 from the calculation of capacitance–voltage curve, which is comparable higher than previously reported La2O3 or Yb2O3 film.

Characteristics of chemical mechanical polishing using graphite impregnated pad

This paper introduces a new design for polishing pads that eliminates the need for built-in pores. Instead, a polyurethane matrix is impregnated with nanographite particles to form a graphite impregnated pad. The surface characteristics as well as the friction force, slurry flow rate, and material removal rate when polishing a dielectric oxide film were experimentally measured and compared with those for conventional porous polishing pads. The results reveal that the proposed pad has an approximately 40% lower dressing rate and consequently greater tool life. Further, use of the impregnated pad reduces slurry consumption as the removal rate at slurry flow rates of <100 ml/min is significantly higher than that for porous pads. The increased removal rate can be attributed to adsorption of slurry onto the large surface area of the nanographite particles. The results suggest interesting possibilities for significant reduction in the cost associated with CMP processing.

Deposition of Al doped ZnO layers with various electrical types by atomic layer deposition

AlZnO thin films with various Al/Zn composition ratios were deposited by atomic layer deposition (ALD) at 200 °C. The effect of the composition of the AlZnO films on their electrical and optical characteristics was investigated. The AlZnO films with an Al content of up to 10 at.% showed high conductivity, while further increasing in the Al content resulted in the abrupt formation of an insulating oxide film. The lowest electrical resistivity of the ALD-deposited AlZnO film was 6.5 × 10 − 4 [Ω cm] at 5 at.% Al. The AlZnO films with up to 5 at.% Al exhibited crystalline phases and a near-band-edge emission. With increasing Al content, the optical band edge showed a blue shift, and a sudden shift associated with an insulating bandgap was observed in the AlZnO films containing 20 at.% Al.

ChemInform Abstract: In situ Investigation of Duplex Semiconducting Films on Tin.

The passive film on tin formed under dynamic conditions represents a duplex layer of the same oxidation state, with a stepwise concentration profile of two semiconducting or almost insulating oxide films in series. Their electrochemical properties are limited by their electronic properties. The electrode capacity (C) and photopotential (Eph) were measured in situ during oxide formation and reduction on tin in slightly alkaline solution. Analysis showed that the changing electronic properties of the oxide formed have a great impact on Eph and C. The formation of the inner SnO2 layer takes place homogeneously all over the surface with constant thickness. Schottky-Mott type of behaviour was found, indicating a surface donor concentration of 10 exp 15 cm-1 and a flat band potential vs. SCE, Efb, of -0.95 V. For the outer layer the changes of electronic properties with increasing film thickness, as well as ageing processes, limit the validity of all electronic models with constant parameters. The oxide/hydroxide ratio increases with anodic polarization. The reaction is favoured by a free-energy decrease. At higher potentials, especially under illumination, the electrode is covered with a very stable SnO2 species which is difficult to reduce.

On the strength of triboemission in sliding of diamond on single crystal silicon

Triboemission is a phenomenon associated with the sliding of variety of materials. The phenomenon is thought to be related to wear of diamond tools used in precision machining of semiconductors. As such, the physics of emission has recently acquired importance. Many researchers studied emission during scratching of solid surfaces. They observed that the intensity of tribo-induced emission of the electrons, ions, and photons decrease in the order: insulator>semiconductor> conductor. Many experiments conducted to compare the emission of negatively-charged particles in case of the semiconductors Si with that from selected insulators have reported a clear decreasing trend of the tribo-emission intensity as contact progressed over the same wear track for diamond-on-Si. Despite that all of these experiments were performed in vacuum, the origin of the weak signals and the decrease of signal strength in the case of Si centred on the presence of dielectric silicon oxide films formed in air during surface preparation or because of the samples being of mono-crystalline nature. This paper offers an alternative explanation to the behaviour of tribo-emitted particles based on the pressure induced semi-conductor-to-metallic phase transformation that takes place in Si during sliding. It is shown that due to repeated sliding, the wear tracks experience a semiconductor-to- metal transformation that renders the bulk of material immediately under the diamond slider conducting.

Synthesis of Self-Assembled Island-Structured Complex Oxide Dielectric Films

A self-assembly driven process to synthesize island-structured dielectric films is presented. An intermetallic reaction in platinized silicon substrates provides preferential growth sites for the complex oxide dielectric layer. Microscopy and spectroscopy analyses have been used to propose a mechanism for this structuring process. This provides a simple and scalable process to synthesize films with increased surface area for sensors, especially those materials with a complex chemistry. The ability of these island-structured dielectric films to improve sensitivity by a factor of 100 compared to continuous films in applications as substrates for surface-enhanced Raman scattering (SERS) is demonstrated.

Depositon of Dielectric Films with Inductively Coupled Plasma‐CVD in Dependence on Pressure and Two RF‐Power‐Sources

AbstractThis paper presents the investigations of thin dielectric silicon oxide (SiOx) and silicon nitride (SiNx) films deposited below 100 °C by a plasma enhanced chemical vapour deposition (PECVD) using an inductively coupled plasma (ICP)‐source. The influence of the deposition pressure and the applied RF‐power to the plasma from the ICP‐source and a second RF‐power at substrate electrode on the characteristics of the deposited films are studied. The investigated characteristics are refractive index R.I. at 632 nm, deposition rate Rdep, stress σ and etching rate Retch in buffered hydrofluoric acid (BHF). Measurements from electron spectroscopy for chemical analysis (ESCA) support the investigations. The results are discussed and compared with other PECVD deposition methods. A significant influence of the RF‐generator connected to substrate electrode on etching rate and hence on film quality is identified for SiOx but the converse effect is identified for SiNx‐films.

Characteristics of high- k dielectric ECR-ALD lanthanum hafnium oxide (LHO) films

In this study, we investigated the characteristics of various lanthanum hafnium oxide (LHO) films with different lanthanum (La) concentrations deposited by an electron cyclotron resonance plasma-enhanced atomic layer deposition (ECR-ALD). Tris(isopropyl-cyclopentadienyl)lanthanum (La(iPrCp) 3) and tetrakis(ethylmethylamino)hafnium (TEMAHf) were utilized as the La and hafnium (Hf) precursors, respectively. When the La/(La + Hf) atomic percent ratio was 49.1%, the growth rate of the LHO film was 0.5 Å/cycle, with a dielectric constant of 16.3. As the La concentration was increased, the dielectric constant decreased. In addition, we found that a La-hydrate phase (La–O–H) can be easily formed when the La/(La + Hf) is over about 50%.

Room-Temperature Cosputtered HfO[sub 2]–Al[sub 2]O[sub 3] Multicomponent Gate Dielectrics

Hafnium oxide-aluminum oxide (HFAIO) dielectric films were cosputtered using HfO 2 and Al 2 O 3 targets, and their properties are studied in comparison with pure HfO 2 films. The X-ray diffraction studies confirmed that the HfO 2 films are nanocrystalline with a monoclinic phase. The as-deposited HfAIO films with a chemical composition of (HfO 2 ) 0 . 86 (AI 2 O 3 ) 0 . 14 are amorphous even after annealing at 500°C. Further, the cosputtered films show a slight reduction in leakage current. The leakage current density may be significantly reduced below 3 × 10 -10 A cm -2 at an electric field of 0.25 MV/cm when applying the proper radio-frequency bias to the substrate.

Electrical conductivity measurement of silicon wire prepared by CVD

The electrical resistivity of a silicon nanowire formed from Si 2H 6 by CVD was measured using microprobes equipped with SEM. The resistivity of 6.58 × 10 5 Ω cm at room temperature was obtained from the current–voltage ( I– V) curve for the wire with both ends fused to the probes. The non-linear I– V curve measured only by contacting the wire with the probes could be explained by the resistivity in a series of silicon and dielectric thin oxide films formed on the silicon nanowires.

Influence of strong electric fields on the growth, modification, and destruction of thin oxide films at the titanium surface

The influence of strong electric fields (∼107 V/cm) on the growth, modification, and destruction of thin oxide films at the metal surfaces are studied for a titanium tip of a scanning tunneling microscope (STM) oxidized in oxygen at different tip potentials. The spectroscopic measurements show that, in sufficiently strong fields (V≤−7.5 V) preventing migration of oxygen ions from the surface to bulk, the dielectric oxide films can form even for exposures of ∼10 L. At voltages V>−7.5 V, i.e., at lower fields, as well as for the opposite polarity, the conducting oxide films containing predominantly Ti+2 and Ti+3 ions are formed at the tip for the same exposures. The possibility of structural modification in the electric field of STM is demonstrated for titanium nanooxides.

Modeling of the evolution of dielectric loss with processing temperature in ferroelectric and dielectric thin oxide films

It was experimentally found that the evolution of dielectric loss with processing temperature displays a common trend in ferroelectric and dielectric thin oxide films; first an increase and then a decrease in dielectric loss when the processing temperature is gradually raised. Such a dielectric response of ferroelectric/dielectric thin films has been theoretically addressed in this work. We propose that at the initial stage of the crystallization process in thin films, the transformation from amorphous to crystalline phase should substantially increase the dielectric loss. Then, with further increase in the processing temperature, the coalescent growth of small crystalline grains into big ones could be helpful in reducing the dielectric loss by lowering grain boundary densities. The obtained experimental data for (Ba,Sr)TiO3 thin films 500 nm in thickness were analyzed in terms of the model developed and shown to be in reasonable agreement with the theoretical results.