Rapid Annealing Process Research Articles

Effect of Rapid Thermal Annealing Time on the Structural and Optical Properties of Layered Structured SiOx/Au/SiOx Film

In this work, layer structured silicon suboxide/gold/silicon suboxide (SiOx/Au/SiOx) films were prepared by using plasma enhanced chemical vapor deposition assisted with hot wire evaporation technique. Post rapid thermal annealing (RTA) process was done on the as-prepared films for 100, 500 and 700s at constant temperature of 800oC in vacuum ambient. Effects of RTA process on the structural and morphological properties of films were studied using FE-SEM, depth profiling and XRD measurement. While, surface plasmon resonance (SPR) phenomenon exhibited by Au particles was investigated via the optical absorption spectra. SPR signals can be exhibited by sample annealed for longer time duration. Individual Au islands tend to form the spherical shape as a whole. Diffusion of Au particles towards the surface of SiOx film is temperature dependent and crystallite size of Au enlarges with the rapid thermal annealing time.

Structural improvement of CVD multi-walled carbon nanotubes by a rapid annealing process

Generally, due to structural disorders in multi-walled carbon nanotubes (MWCNTs) synthesized by chemical vapor deposition (CVD), most of their properties are much below the expected values. A novel technique has been developed in this investigation for structural improvement of CVD MWCNTs using a rapid annealing process. Direct observation by transmission electron microscope (TEM) indicates obvious structural changes in the nanotubes after a rapid annealing process between 2000°C and 2800°C, while nanotubes with twisty shells and kinked walls have been observed as the annealing temperature approaches 3000°C. Decrease of ID/IG ratio in Raman spectra, increase of the starting oxidation temperature observed in Thermogravimetric analysis (TGA), as well as increase in electrical conductivity of nanotube powders suggests the reconstruction toward more ordered nanotube structure after a rapid high temperature annealing process.

Effects of Deposition Parameters and Annealing Temperatures on the Characteristics of the Sr<sub>0.6</sub>Ba<sub>0.4</sub>Nb<sub>2</sub>O<sub>6</sub> Thin Films

Sr0.6Ba0.4Nb2O6 (SBN) thin films were prepared by radio frequency (RF) sputtering onto the SiO2/Si/Al and Pt/Ti/Si substrates to form the MFIS and MFM structures. Their deposition rates increased with decreasing oxygen concentration and with increasing RF power. Their optimal deposition parameters were the substrate temperature of 500°C, chamber pressure of 10 mTorr, oxygen concentration of 40%, and RF power of 120W, respectively. The rapid temperature annealing (RTA) process had large effects on the grain growth of the SBN thin films. The effects of different RTA temperatures on the leakage current density - electrical field curves and the capacitance - voltage curves of the SBN thin films were also investigated.

Investigation of Annealing Effect on the Electrical and Optical Properties of ITO Film Prepared by Sol-Gel Process

Indium tin oxide thin film (ITO film) has been deposited onto the quartz glass by a sol-gel process, followed by annealing in air. The temperature range from 200 to 800 °C and the annealing effect on the optical, electrical and structural properties of ITO films has been studied in detail. ITO Films with a thickness of 100nm had an optical transparency up to 90% in the wavelength range of visible spectrum. The ITO film showed minimum resistivity of 1.65×10-3Ω.cm-1 when annealing temperature was 600°C in air. the rapid annealing process may contribute to the electrical property of ITO film for the densification of the micro structure. but the process may lead to the decrease of transparency for the reflection caused by grain boundary.

Preparation and properties of Mg0.2Zn0.8O:Al UV transparent conducting thin films deposited by RF magnetron sputtering at room temperature with rapid annealing

Mg0.2Zn0.8O:Al UV transparent conducting thin films were deposited by RF magnetron sputtering at room temperature with a rapid annealing process. Effects of sputtering power, argon gas pressure and annealing temperature on structure, optical and electrical properties of Mg0.2Zn0.8O:Al films were investigated. The experimental results show that Mg0.2Zn0.8O:Al thin films exhibit high preferred c-axis-orientation. The sputtering power, argon gas pressure and annealing temperature all exert a strong influence on the electrical resistivity of Mg0.2Zn0.8O:Al thin films due to the variation of carrier concentration and mobility in films derived from the change of effective doping and crystallinity. The lowest electrical resistivity of Mg0.2Zn0.8O:Al thin films is 3.5 × 10−3 Ω·cm when the sputtering power is 200 W, the argon gas pressure is 2.0 Pa and the annealing temperature is above 500 °C. The transparent spectrum range of Mg0.2Zn0.8O:Al thin films extend to ultraviolet band and the optical transmittance is between 80 and 90%, but the sputtering power, argon gas pressure and annealing temperature all exert little influence on optical transmittance.

New Observations and Impacts of Diameter-Dependent Annealing Effects in Silicon Nanowire Transistors

In this paper, an abnormal diameter-dependent annealing (DDA) effect in silicon nanowire transistors (SNWTs) is observed and its impacts on device performance are investigated. It is found that the implanted dopants diffuse faster in thin nanowires than those in thick nanowires during the rapid annealing process, which results in underestimating the length of designed source/drain (S/D) extension (SDE) region in SNWTs. The impacts of DDA on SNWTs are studied in terms of S/D series resistance (RSD), tradeoff between parasitic capacitance and resistance, and process parameter dependence. The random dopant fluctuations (RDF) in nanowire SDE regions (SDE-RDF) are also discussed. The results indicate that SDE-RDF induced RSD variation in SNWTs is enhanced by DDA effects, which aggravates the driving current variations with the downscaling of SNWT diameter.

The effect of heating rate on the structural and electrical properties of sol–gel derived Al-doped ZnO films

Al-doped ZnO (AZO) films are prepared by sol–gel method with a proper annealing procedure. For the first time, we find that the heating rate which is normally neglected during the post annealing process plays a significant role in improving AZO properties. The AZO film with nanorod structure is obtained by using a rapid heating rate. The AZO nanorods can provide a faster conduction pathway for charge transport due to the high crystal quality and thus enhance the conductivity of the film significantly. After hydrogen treatment, the AZO nanorod film exhibits a minimum resistivity of 1.4 × 10 −3 Ω cm. This approach to the preparation of AZO nanorods by a simple rapid annealing process may be helpful for the development of sol–gel-derived TCO films.

Rapid thermal annealed Al-doped ZnO film for a UV detector

A low-resistive Al-doped ZnO (AZO) film was achieved by rapid thermal annealing. A co-sputtering method was used in the initial growth of AZO films and a rapid annealing process was performed on the as-deposited AZO film under N 2 atmosphere for 3 min. An as-deposited AZO film had an optical transmittance of 84.78% at 550 nm and a resistivity of 7.8 × 10 − 3 Ω cm. A rapid annealing process significantly improved the optical transmittance and electrical resistivity of the AZO film to 99.67% and 1 × 10 − 3 Ω cm, respectively. The structural changes of the AZO films were investigated by X-ray diffraction and transmission electron microscopy. The high quality AZO film was used to fabricate a metal–semiconductor–metal (MSM) structure for a UV detector. The MSM device provided a stable current of 25 μA at a bias of 2 V in a dark condition. Under UV illumination, the MSM device was highly responsive to UV light uniformly and repeatedly, and it enhanced the current by 80% at 45 μA. This rapid thermal annealing process may provide a useful method to fabricate quality AZO films for photoelectric applications with a low thermal budget.

Ohmic contacts to polycrystalline 3C–SiC films for extreme environment microdevices

Ohmic contact characteristics were studied under the surface treatments of poly 3C–SiC films heteroepitaxially grown on SiO 2/Si wafers by APCVD. The poly 3C–SiC surface was polished to remove submicron-sized roughness and to get flat and smooth surface using chemical–mechanical polishing (CMP) process. However, some scratching marks on the poly 3C–SiC have remained surface due to the mechanical defect of CMP process. To remove a part of subsurface damage and scratching marks, the polished surface was oxidized by wet-oxidation furnace and it has been etched by diluted HF solution. Titanium tungsten (TiW) thin film was deposited on the surface treated poly 3C–SiC using circular transmission line model as a metallization process and it was annealed through the rapid temperature annealing (RTA) process to improve interfacial adhesion. The contact resistivity of the treated 3C–SiC surface was measured as the lowest 1.2 × 10 −5 Ω cm 3 at 900 °C for 45 s.

Fabrication of polycrystalline La0.67(Sr1−x Cd x )0.33MnO3 thin films on Si(100) substrates by sol–gel process

Polycrystalline La0.67 (Sr1-xCdx)0.33MnO3 (LSCMO x = 0, 1/8, 2/8, 3/8, 4/8) films were fabricated on Si(100) single crystal substrates by the sol–gel and the rapid annealing process. According to the field-emission scan electron microscopy (FE-SEM) observation and X-ray (XRD) diffraction studies, all the samples are single phase. We also prepared a series of samples by fixing the ratio of La at 0.67. It is shown that with increase of the doping amount x in La0.67(Sr1-xCdx)0.33MnO3, the average A-site cation radius 〈A〉 decreases, the temperature of metal-insulator transition (TMI) decreases monotonically, ρ and magnetoresistance (MR) values increase dramatically, which can be explained by the lattice effects. The enhanced MR effect at low temperature for the LSCMO film is attributed to the suppression of the spin dependent scattering of polarized electrons at the grain boundaries. The low-field magnetoresistance values under 0.3 T are observed to be 2.48% (x = 0) at 300 K and 37.5% (x = 4/8) at 85 K, respectively.

PREPARATION OF Pb(Zr0.35Ti0.65)O3 FILMS ON CONDUCTING OXIDE Ga-DOPED ZnO FILMS FOR TRANSPARENT FERROELECTRIC THIN-FILM TRANSISTORS

ABSTRACT We have investigated the feasibility of the deposition of ferroelectric PZT films on transparent conducting Ga-doped ZnO (GZO) films, for transparent ferroelectric thin-film transistors. Low resistive and high c-axis oriented GZO films are prepared at the substrate temperature of 250°C using the dc magnetron sputtering method. PZT films are deposited at low substrate temperature and subsequently crystallized by means of the rapid annealing process in a high vacuum to minimize the reaction of PZT with GZO films. Various vacuum-annealing conditions are investigated to get high-quality PZT films, which show single perovskite phase with a random orientation. The optimized PZT/GZO capacitors have somewhat unsaturated P-E hysteresis loops with the values of remanent polarization and coercive field of about 4.5 μC/cm2 and 145 kV/cm, respectively.

Application of UV-Raman Spectroscopy for Characterization of the Physical Crystal Structure Following Flash Anneal of an Ultrashallow Implanted Layer

Ultraviolet (UV) Raman spectroscopy provides new information on crystal structure and changes in structure with depth, not provided by conventional techniques. Characterization of the recrystallization process in ultrashallow B- or -implanted layers with preamorphization implantation of Ge on silicon was performed by nondestructive Raman spectroscopy utilizing multiwavelength UV excitation. To recrystallize damaged layers after ion implantation, a rapid annealing process was carried out in a millisecond flash anneal system. By making use of the shallow penetration depths of UV light in silicon, we can distinguish Raman signals of single-crystalline, deficiently recrystallized, as well as amorphous silicon, and thereby characterize the ultrashallow region at depths of several nanometers from the surface. Following the annealing, a single-crystalline lattice image was observed for a recrystallized layer using transmission electron microscopy. However, an intense Raman peak associated with deficiently recrystallized silicon that is spectroscopically equivalent to polycrystalline silicon was detected from the recrystallized layer. The deterioration is presumably correlated with the insufficient activation of B atoms in the recrystallized layer from measurements using the combination of secondary ion mass spectroscopy and spreading resistance profiles. Ultraviolet Raman spectroscopy is a very powerful, nondestructive tool to characterize the physical structure of the ultrashallow junction formation.

Successive occurrence of ferromagnetic and shape memory properties during crystallization of NiMnGa freestanding films

Ni 50Mn 30Ga 20 films of 13 μm thickness were fabricated by DC magnetron sputtering on unheated glass substrates. The As-deposited films are partially crystalline and crystallize during rapid annealing. The successive appearance of ferromagnetic and shape memory properties was observed as the annealing temperature was increased. Ferromagnetic properties evolved after annealing at 400 °C for 0.5 h, while thermal annealing of at least 600 °C for 0.5 h led to polycrystalline films that transformed reversibly and martensitically as shown by structural analysis and differential scanning calorimetry and confirmed by mechanical spectroscopy data. Magnetic measurements also revealed the influence of the post deposition annealing on the ferromagnetic hysteresis. Transition temperatures and reaction enthalpies of the martensitic phase transformation were strongly influenced by the temperature of the rapid annealing process. X-ray absorption fine-structure (XAFS) spectroscopy proved these changes to be related to the change in the chemical order. It is proposed that the annealing data reflect the evolution of the crystalline state. Ferromagnetic order is established already in nano-grained samples whereas the shape memory effect is only observed above a critical grain size.

TbFe<sub>2</sub>/α-Fe Nanocrystalline Exchange Coupling Magnetostrictive Films

In this paper, the influences of annealing temperature on TbFe magnetostrictive film magnetic and magnetostrictive characteristics were discussed. TbFe films were prepared by RF magnetron sputtering. XRD patterns indicate that polycrystalline films consisting mainly of a-Fe and TbFe2 Laves phase could be obtained through rapid cycle annealing process (RCAP) at higher annealing temperature. Grain sizes could be controlled through varying annealing temperature. From film hysteresis loops measured by VSM, it has been found that the annealing treatment can improve TbFe film in-plane magnetization at 1600 kA.m-1 external field, and decrease in-plane coercivity. Magnetostriction of annealed TbFe films measured by optical cantilever deflectometer is better than as-deposited films at 40 kA.m-1 external magnetic field.

Effects of Rapid Cycle Annealing Temperature on TbFeMagnetostrictive Films

The effects of annealing temperature on TbFe films prepared by dcmagnetron sputtering were discussed. X-ray diffraction patternsindicate that these polycrystalline films consisting mainly of α-Fe andTbFe2 lave phase with grain sizes less than 25 nm can be obtainedby a rapid cycle annealing process. Grain sizes can be controlled byvarying annealing temperatures. Film hysteresis loop studies show thatannealing treatment can improve TbFe film in-plane soft magneticperformances. Magnetic domain structures explored by a magnetic forcemicroscopy show that in the as-deposited films, maze domain structuresexist, hence it possesses perpendicular anisotropy and largeranisotropic constant Ku. No domains are observed whenannealing temperature is lower than 400 degrees C. However, maze domainstructures appear again when annealing temperature is higher than400 degrees C. Two maxima of magnetostrictive coefficients areobtained at annealing temperatures of 300 degrees C and 500 degrees C inthe presence of a 40 kA.m−1 external magnetic field.

A New Approach for Rapid Annealing of Medium Carbon Steels

The kinetic effects of high magnetic field on the solid‐state phase transformation during cooling in medium carbon steel are investigated. Imposing of a 14‐Tesla magnetic field has promoted the proeutectoid ferritic transformation from austenite, and resulted in uniform and refined microstructure of ferrite and pearlite even under rapid cooling. Insight into the rapid magnetic annealing process contributes to the development of new heat‐treatment techniques with high productivity.

Fabrication and characterization of freestanding NiMnGa films

ABSTRACTFreestanding Ni50Mn30Ga20 films of 13 μm thickness were fabricated by DC magnetron sputtering and analyzed. Magnetic measurements revealed the influence of the post deposition rapid thermal annealing process on the ferromagnetic hysteresis. Ferromagnetic properties evolved after annealing at 400°C. Thermal annealing of at least 600°C led to polycrystalline films that transformed reversibly and martensitically as shown by structural analysis and differential scanning calorimetry. Transformation temperatures and enthalpies of transformation of the martensitic transformation were strongly influenced by the temperature of the rapid annealing process. It is proposed that the annealing data reflect the evolution of the crystalline state.

Thermo-Sensitive Ba 0.64 Sr 0.36 TiO 3 Thin Film Capacitors for Dielectric Type Uncooled Infrared Sensors

Ba0.64Sr0.36TiO3 (BST) thin films are prepared on Pt/Ti/SiO2/Si3N4/SiO2/Si substrates by a sol-gel method. Thermo-sensitive BST thin film capacitors with a Metal-Ferroelectrics-Metal (M-F(BST)-M) structure are fabricated as the active elements of dielectric type uncooled infrared sensors. XRD are employed to analyze the crystallographic structures of the films. AFM observations reveal a smooth and dense surface of the films with an average grain size of about 35 nm. Rapid temperature annealing (RTA) process is a very efficient way to improve crystallization quality. The preferable annealing temperature is 800°C for 1 min. The butterfly shaped C-V curves of the capacitors indicate the films have a ferroelectric nature. The dielectric constant and dielectric loss of the films at 100 kHz are 450 and 0.038, respectively. At 25°C, where the thermo-sensitive capacitors work, the temperature coefficient of dielectric constant (TCD) is about 5.9 %/°C. These results indicate that the capacitors with sol-gel derived BST thin films are promising to develop dielectric type uncooled infrared sensors.

Superconducting properties of MgB2 thin films prepared on flexible plastic substrates

Superconducting MgB2 thin films were prepared on 50-μm-thick, flexible polyamide Kapton-E foils by vacuum co-deposition of Mg and B precursors with nominal thickness of about 100 nm and a subsequent ex situ rapid annealing process in an Ar or vacuum atmosphere. In the optimal annealing process, the Mg–B films were heated to approximately 600 °C, but, at the same time, the backside of the structures was attached to a water-cooled radiator to avoid overheating of the plastic substrate. The resulting MgB2 films were amorphous with the onset of the superconducting transition at Tc,on≈29 K and a transition width of approximately 3 K. The critical current density was >7×105 A/cm2 at 4.2 K, and its temperature dependence indicated a granular film composition with a network of intergranular weak links. The films could be deposited on large-area foils (up to 400 cm2) and, after processing, cut into any shape (e.g., strips) with scissors, or bent multiple times, without any observed degradation of their superconducting properties.

Carrier compensation behaviors in Si-doped AlxGa1-xAs epilayers due to thermal annealing

Heavily doping methods into semiconductor epilayers have attracted attention because of the interest in both an increase of the conductance of an active layer and an reduction of the electrical resistance to improve the device performance of electronic and optoelectronic devices [1–3]. Among various heavily doped epilayers, heavy Si doping in Alx Ga1−x As layers is particularly interesting due to the enhancement of the intermixing behavior of group III atoms resulting from the formation of the compensation centers such as Ga vacancies [4–6]. Even though few works concerning the compensation mechanisms in semi-insulating GaAs have been performed [7], investigations of the mechanisms in Si-doped Alx Ga1−x As layers due to thermal annealing have not yet been done. This letter reports on Van der Pauw-Hall effect measurements which were carried out to determine the carrier density and the mobility of as-grown and annealed Si-doped Alx Ga1−x As layers and photoluminescence (PL) measurements which were performed in order to investigate the optical behaviors in the layers. A possible compensation mechanism is presented on the basis of the experimental results. The Alx Ga1−x As epilayers studied in this work were grown on semi-insulating GaAs(100) substrates by using molecular beam epitaxy (MBE). The surface of the substrate was cleaned chemically with acetone, trichloroethylene, methanol and deionized water, alternately. The substrates were etched in a H2SO4 : H2O2 : H2O (5 : 1 : 1) solution for 90 s and rinsed in deionized water thoroughly. After the GaAs wafers were cleaned chemically, they were mounted onto a molybdenum susceptor by soldering using indium. Prior to Alx Ga1−x As growth, the substrates were thermally cleaned in order to remove the oxide layer at 600 ◦C for 10 min in As atmosphere in the growth chamber at a pressure of 2.5 × 10−6 Torr. Alx Ga1−x As epilayers were deposited onto a GaAs buffer layer with 1 μm thickness. After a 100-A undoped Al0.25Ga0.72As layer was grown, a 2000-A Si-doped Al0.25Ga0.75As active layer was grown. The rapid thermal annealing (RTA) process was performed in a nitrogen atmosphere with a tungsten-halogen lamp as the thermal source, and