Koichi Kugimiya

Preparation and Properties of Lead Zirconate-Titanate Thin Films

Lead zirconate-titanate (PZT, PbZrxTi1-xO3, x=0.2-0.9) films with submicron thickness (600-900 nm) were prepared using an rf-magnetron sputtering technique. The crystal structure and the orientation of the films were studied as a function of the substrate temperature. The relationships between electric properties and the film compositions were elucidated. The films of x=0.90 exhibit a large remanent polarization of 46 µC/cm2 and small coercive force of 28 kV/cm. In addition, no fatigue after >1011 cycles under an accelerated bipolar stressing was observed.

Low loss MnZn-ferrites: frequency dependence of minimum power loss temperature

A simple method was applied to separate magnetic loss into hysteresis loss, eddy current loss and residual loss. Residual loss becomes dominant at high frequency, and is assumed to be the main cause of the frequency dependence of the minimum loss temperature. The origin of the residual loss is thought to be domain wall resonance. Experiments along this hypothesis have led to new low loss ferrites with magnetic loss of less than 100 kW/m/sup 3/ at 1 MHz, 50 mT and 80 degrees C. >

Soft magnetic properties of nano-structure-controlled magnetic materials

The soft magnetic properties of Nano-Structure-Controlled NANOCON magnetic materials have been studied, The NANOCON materials consist of Fe-based soft magnetic metal particles which are separated from each other by insulation layers of metal oxides on the order of 10-nm thick, The permeability of NANOCON materials was constant up to 10 MHz due to the small isolated particles size compared with skin depth. The value of quality factor (Q) and the peak frequency of Q could be adjusted by the particle size of NANOCON materials due to the minimization of eddy current losses due to the particle isolation. >

CW Laser Annealing of Polycrystalline Silicon on SiO2 and Effects of Successive Furnace Annealing

CW Ar laser annealing was carried out to reduce the resistivity of polycrystalline silicon implanted with light doses of 1×1012-5×1014B+/cm2. Laser annealing, actually laser melting, and successive furnace annealing effectively reduced the resistivity to almost that of single crystal silicon. TEM, OM and stress observations revealed that the reduction was due primarily to the grain growth of polycrystalline silicon and secondarily to stress relief, from 9×109 dyne/cm2 to 5×109 dyne/cm2, caused by annealing. Grain growth of up to about 3×100 µm and bamboo-joint-like growth were observed.

Blink Furnace Annealing of Ion-Implanted Silicon

A very short annealing of a few seconds duration was carried out by irradiating ion-implanted Si wafers with infra-red radiation emitted from hot Si walls. At low temperatures, the activation of impurities was mostly due to the recrystallization of the amorphous layers and to the annihilation of ion-implanted damage; and at high temperatures to thermal agitation. Full activation was generally realized by blink annealing of 10 s at 1000°C and 1 s at 1100°C without noticeable impurity diffusion. Supersaturation of As was electrically observed.

Characterizat Ion of thin Pzt Films on Platinlm Films

Anomalous layers 20-40nm thick were found at the interfaces of lead zirconate-titanate films and Pt electrode films. Detailed study has shown evidence that absorption of PbO by Pt during sputtering resulted in a Pb deficiency in the PZT films and the formation of PbTi 3 O 7 phase. The anomaly was also partly due to island formation at the initial PZT film deposition which allowed PbO to react with Pt films. The Pb controlled PZT films 50nm thick exhibited excellent ferroelectric properties comparable to thicker ones.

101-Stage 2 µm gate ring oscillators in laser-grown silicon islands embedded in SiO 2

E/D MOS test transistors and 101-stage 2 µm gate E/D MOS ring oscillators were fabricated in laser-grown single- and multicrystal islands embedded in oxide substrates. Most transistors showed good<tex>I-V</tex>characteristics, short-channel effects, and kink effects. Ring oscillators had a switching delay per stage (τ<inf>Pd</inf>) of 0.4 ns and a power-delay product (τ<tex>_{Pd} \middot P_{d}</tex>) of 2.5 PJ at a supply voltage (V<inf>DD</inf>) of 10-15 V. It was noted that different crystal orientations of the islands posed no difficulty in processing and V<inf>T</inf>control when applied to short channel devices, and that enhanced boundary diffusion results in occasional malfunctional transistors and erroneous high surface electron mobilities (µ<inf>se</inf>).

Magnetic properties of nanostructure controlled FeAlSi/FeAlSiO multilayers

FeAlSi/FeAlSiO multilayers prepared by the pulse reactive sputtering were investigated. It was found that the layered structure had a high thermal stability over the ordering temperature of FeAlSi. In consequence, a saturation magnetic flux density of 1.4-1.5 T, a high isotropic initial permeability of 2000-10000 at 1 MHz were obtained even after the thermal annealing above 500/spl deg/C. >

A New Interferometric Alignment Technique with Holographic Configuration

A new interferometric alignment technique using a holographic configuration with a precision of the order of tens of nm has been developed for registering a grating on a substrate to an interference fringe of two conjugate beams in a space. The alignment between a grating and a fringe was determined from the moire image generated by the beams diffracted from the grating, and a theoretical analysis was performed to calculate the intensity of the moire image. The experimental results were in good agreement with the calculations. The application of the method to a wafer stepper with submicron resolution is proposed.

Piezoelectric Properties of Nanostructure-Controlled Lead-Perovskite-Based Ceramics

We studied the piezoelectric properties for structure-controlled ceramics of (Pb 0.9 Sr 0.1 )(Mg 1/3 Nb 2/3 ) 0.255 Ti 0.38 -Z 0.365 O 3 prepared by the ultrafine powder process called the «nanopowder process». The dense and uniform fine-grained ceramics in this system, which had the relative density of 97.5% and the average grain size of 1.9 μm, wire obtained by this process. The sample prepared by this process showed the large dielectric constant of above 5300 and the high electromechanical coupling factor k 31 of 0.41. It was found that, the nanopowder process is effective to improve the piezoelectric property. The maximum value of the piezoelectric constant |d 31 | was 356×10 -12 m/V