Effective Annealing Time Research Articles

Well-ordered self-assembled nanostructures of block copolymer films via synergistic integration of chemoepitaxy and zone annealing.

It is an extremely challenging task to fabricate macroscopically well-ordered nanostructures of block copolymers in a limited annealing time. In this work, we propose a novel integrated strategy of chemoepitaxy and zone annealing to direct the self-assembly of lamella-forming block copolymers. Large-scale numerical simulations corroborate that the integrated strategy has the capability to generate well-aligned and well-oriented lamellae over a macroscopic area via the synergy between the alignment guidance of the chemical template and the defect annihilation of zone annealing, even though the guiding stripes of the chemical template are extremely sparse. It is further demonstrated that the effective annealing time to achieve the well-ordered nanostructures is strongly dependent upon the pitch of guiding stripes and the thickness of block copolymer films. This work provides an instructive example for boosting the directing efficiency of chemoepitaxy through the integrated strategy, and lays the groundwork for rapidly fabricating well-ordered nanostructures of block copolymer nanolithography.

Development of FeSiBNbCu Nanocrystalline Soft Magnetic Alloys with High B s and Good Manufacturability

In order to develop Fe-based nanocrystalline soft magnetic alloys with high saturation magnetic flux density (Bs) and good manufacturability, the effect of the Nb content on the thermal stability, microstructural evolution and soft magnetic properties of Fe78−xSi13B8NbxCu1 (x = 0, 1, 2 and 3) alloys were investigated. It is found that proper Nb addition is effective in widening the optimum annealing temperature range and refining the α-Fe grain in addition to enhancing the soft magnetic properties. For the representative Fe76 Si13B8Nb2Cu1 alloy, the effective annealing time can be over 60 min in the optimal temperature range of 500–600°C. FeSiBNbCu nanocrystalline soft magnetic alloys with desirable soft magnetic properties including high Bs of 1.39 T, low coercivity (Hc) of 1.5 A/m and high effective permeability (μe) of 21,500 at 1 kHz have been developed. The enhanced soft magnetic performance and manufacturability of the FeSiBNbCu nanocrystalline alloys are attributed to the high activated energy for the precipitation of α-Fe(Si) and the second phase. These alloys with excellent performance have promising applications in electromagnetic fields like inductors.

Optimization of thermal stability and soft-magnetic properties of FeSiBPCuNb alloys by Nb content tuning

The effects of Nb content on the thermal stability, microstructural evolution and soft-magnetic properties of nanocrystalline Fe83−xSi4B10P2Cu1Nbx alloys were systematically investigated. Appropriate Nb addition was found to be effective both in prolonging operative annealing time and annealing temperature range and in improving magnetic softness by tuning the size and distribution of nano-sized α-Fe inclusions. The effective annealing time of 30min over temperature range of 723–793K, in combination with desirable soft-magnetic properties including high saturation magnetic flux density (Bs) of 1.73T, low coercivity (Hc) of 4.5A/m and high effective permeability (μe) of 23,000 at 1kHz, entitles Nb-containing Fe82Si4B10P2Cu1Nb1 nanocrystalline alloy a truly industrial advantage in energy-economic efficiency and great potentials in electromagnetic applications.

A universal value of effective annealing time for rapid oxide nucleation and growth under pulsed ultraviolet laser irradiation

The effective annealing times (t(eff)) for nucleating various oxides from an amorphous matrix under nanosecond pulsed laser irradiation have been determined. The oxides, which had perovskite, bixbyite, anatase, and pyrochlore structures, showed similar t(eff) values for crystal nucleation of around 60 ns. This indicates that the effective annealing time is a good universal value for evaluating pulsed laser-induced oxide nucleation. Time-resolved resistance measurements of tin-doped In2O3 thin films under pulsed laser irradiation showed that crystal nucleation and rapid growth proceeded spontaneously with an instantaneous temperature rise.

Magnetic properties of Fe-based toroidal cores prepared by continuous Joule heating under tensile stress

Fe-based toroidal cores with a permeability value of several hundreds were prepared by the continuous Joule heating method under tensile stress at a high moving velocity of 120cm∕min, corresponding to an effective annealing time of approximately 1.8s, and their magnetic properties were evaluated. The prepared core showed a constant permeability value up to 2MHz and a low magnetic loss compared with those for conventional cores with controlled permeability. An investigation of dc-bias properties of the core suggested that the core has constant and good magnetic properties below the dc-bias field of 1kA∕m which is approximately 50% of the anisotropy field. Consequently, the continuous Joule heating under a tensile stress method at high moving velocity enables us to prepare a long annealed ribbon in a short time with simple equipment and improves productivity for the fabrication process of high performance Fe-based toroidal cores with controlled permeability.

Magnetic Properties of Fe-Based Ribbons and Toroidal Cores Prepared by Continuous Joule Heating Under Tensile Stress

Nanocrystallized Fe73.5Cu1Nb3Si 15.5B7 ribbons with controlled permeability were prepared by using continuous stress-annealing by Joule heating (CSA-JH) method. An optimization of the annealing conditions revealed that a completely developed anisotropy perpendicular to the ribbon axis can be obtained stably in the moving velocity range from 1 to 200 cm/min at the current density of 37.5 A/mm2. In particular, the highest velocity of 200 cm/min achieved the significant reduction in effective annealing time. The core made from the above-mentioned ribbon had good ac-magnetic properties such as constant permeability up to 2 MHz and low magnetic loss compared with those for different types of cores with controlled permeability. Consequently, it was clarified that the CSA-JH method is one of effective techniques for production of high performance toroidal cores with controlled permeability

Activation mechanism of implanted boron in a Si substrate

The recrystallization and dopant activation in the BF2+ implanted samples with a 110 keV/5×1015 cm−2 condition into a Si substrate and annealed with different heating rates to various preset temperatures for zero holding time have been studied. A higher heating rate yielded a higher carrier mobility and a better crystallinity. A statistical model was proposed to characterize the dopant activation. The activated dopant concentration n was expressed as γ exp(−Ea/kT). The pre-exponential term γ is a function of critical temperature Tc, due to a finite melting point of Si, and heating rate. Both the effective activation energy Ea and Tc values decreased with increasing heating rate. With increasing heating rate, the γ term rapidly decreased at low rates due to the shortened effective annealing time, but showed slight increase at high rates due to the decreased Tc value. Low heating rates facilitated the dopant activation via the γ term, while high heating rates enhanced the activation efficiency via the Ea term.

Asymptotic estimates of diffusion times for rapid thermal annealing

Temperature profiles for rapid thermal annealing of ion implanted material are analyzed using asymptotic methods. Although only rapid thermal annealing is discussed, these methods are also applicable to many other annealing processes. Formulas for effective diffusion distance and effective annealing time are given which correct for the deviations of actual annealing profiles from ideal annealing profiles. The three major deviations considered are (1) ramp terms, (2) rising plateaus, and (3) plateau overshoots. The analysis shows that even relatively small deviations can have sizable effects.

Formation kinetics of MoSi2 induced by cw scanned laser beam

Scanned cw laser beams at different scan velocities from 10 to 400 cm/s have been used to study the interaction of thin metal films of molybdenum deposited by electron beam evaporation with single-crystal silicon substrate. Backscattering technique has been used to investigate the growth mechanism of hexagonal silicide MoSi2 as a function of the number of repetitive laser scans. Silicide layers are found to grow at a rate proportional to the square root of the effective annealing time in the whole range of scan velocities. Effective annealing temperatures are calculated for each laser annealing condition, and from an Arrhenius plot a mean value of activation energy for MoSi2 growth is estimated.

Laser annealing for solid-phase thin-film reactions

We propose a scheme for calculating the amount of thin-film reaction as a result of the pulsed annealing induced by laser irradiation. Under ideal conditions, simple analytical solutions are obtained for reaction temperature T (t) if the absorbed laser power P (t) is a step, linear, or polynomial function of t. The thickness of the reacted film is equivalent to that of a thermal (furnace) annealing at an effective temperature Teff for an effective annealing time Δteff. Teff is the peak value of T (t) and Δteff ≃ (kTeff/Ea)mΔt, where m=1 or 1/2 [determined by the function form of T (t) near Teff], Ea is the activation energy of the process, and Δt is the duration of the laser pulse. The present results can also be used as an approximation in some cases of the laser annealing of ion-implanted semiconductors. Effect of antireflective coatings is thus predicted. Preliminary experimental results on the laser annealing for metal-silicide formation are discussed and are compared with the present calculation.