Katsuto Tanahashi

Technique for determination of nitrogen concentration in Czochralski silicon by infrared absorption measurement

A new method is proposed for the determination of the nitrogen (N) concentration in Czochralski silicon by infrared absorption measurement. Two specimens for the determination are cut from the same N-doped Czochralski silicon (wafer). They are subjected to isothermal annealing at 600°C and 750°C for 2 h and quenched in air to hold the quasithermal-equilibrium state in the formation-dissociation reaction of N-related defects. The absorption coefficient of the infrared absorption peak in the differential spectrum between annealed samples is proportional to the total N concentration. The calibration curve between the absorption coefficient and total N concentration is obtained, which is expressed as N/cm3=4.07×1017/cm2 × absorption coefficient of the 963 cm-1 peak.

Estimating lateral straggling of boron profiles ion implanted into crystalline silicon with a tilt angle of 0/spl deg/ using off-angle substrates

Boron was ion implanted into /spl theta//spl deg/ off-angle crystalline silicon substrates with a tilt angle of /spl theta//spl deg/. It is assumed that the B profiles along the ion-beam direction are identical, enabling the lateral straggling of B ion implanted with a tilt angle of 0/spl deg/ to be evaluated experimentally for the first time. The measurements show that the lateral straggling of channeling ions is small.

Characterization of millisecond-anneal-induced defects in SiON and SiON/Si interface by gate current fluctuation measurement

In this paper, we have investigated bulk trap and interface trap density (Dit) caused by millisecond annealing (MSA) using gate current fluctuation (GCF) and charge pumping measurements. We show that the high energy flash lamp annealing (FLA) creates the GCF with a long duration time and it is critical issue to get a stable SRAM operation. FLA creates interface traps localized at the gate edge of MOSFET.

Stress variability control by defects suppression of SiGe Source/Drain using novel SiGe epitaxial growth technique

Abstract We found that pits near the recessed Si side wall of pMOSFET with eSiGe degrade the device variability due to local tensile strain induced in the channel region. This was improved by newly developed SiGe epitaxial growth technique that includes two-step sequences with different amount of additional HCl in SiH4-GeH4-B2H6-HCl-H2 gas mixtures. By using this technique, we achieved saturation drain current (Ion) increase (4%) and improvement both in Ion and threshold voltage variability.

Enhancement of Boron Diffusion in Silicon by Continuous Wave CO2 Laser Irradiation

We investigated the diffusion of boron (B) by the irradiation of cw CO2 laser light. The diffusion of B was enhanced by irradiating the laser light during annealing in Ar/O2 ambient. It was found that the irradiation of the laser light had the effect of enhances on the growth of an oxide layer. The possible mechanism of the enhanced diffusion is that the excess self-interstitials injected by oxidation at a laser-irradiated point assist the diffusion of B.