Ryota Katsumata

Bit Cost Scalable Technology with Punch and Plug Process for Ultra High Density Flash Memory

We propose Bit-Cost Scalable (BiCS) technology which realizes a multi-stacked memory array with a few constant critical lithography steps regardless of number of stacked layer to keep a continuous reduction of bit cost. In this technology, whole stack of electrode plate is punched through and plugged by another electrode material. SONOS type flash technology is successfully applied to achieve BiCS flash memory. Its cell array concept, fabrication process and characteristics of key features are presented.

Optimal device structure for Pipe-shaped BiCS Flash memory for ultra high density storage device with excellent performance and reliability

An asymmetric source/drain profile for select gate and metal salicided control gate are successfully realized on Pipe-shaped Bit Cost Scalable (P-BiCS) Flash memory to achieve data storage device with excellent performance and reliability.

Water absorption properties of fluorine-doped SiO2 films using plasma-enhanced chemical vapor deposition

The water absorption properties of a PE-CVD (plasma-enhanced chemical vapor deposition) fluorine-doped SiO2 film with a low dielectric constant were studied. It was concluded that highly stable F-doped SiO2 film was obtained at F contents from 2.0% to 4.2% (3.2≤k≤3.6) using high-density plasma CVD. However, at F contents higher than 4.2% (k<3.2), the amount of water absorption was markedly increased due to the presence of Si–F bonds, such as Si(–F)2 bonds, which are highly reactive with water. On the other hand, water absorption was observed at every F content for conventional plasma CVD films. Through gas phase component analysis and investigation of the incident ion energy distribution using a quadrupole mass spectrometer, it was confirmed that a high efficiency of gas dissociation and high-energy ion bombardment are the keys to obtaining high-quality films with a high resistance to water absorption.

Fin-Array-FET on bulk silicon for sub-100 nm trench capacitor DRAM

Fin gate array transistor (Fin-Array-FET) fabricated on bulk silicon substrate is applied to the DRAM cell with the deep trench (DT) capacitor. Fin-Array-FET is designed for the 130 nm technology node and beyond by using the 3-D device simulator (HyDeLEOS) and process simulator (HySyProS). It is demonstrated that the on-current of Fin-Array-FET is 62 /spl mu/A/cell that is about 1.7 times as much as conventional planer array FET, keeping the off-current 0.1 fA/cell. It is also demonstrated that Fin-Array-FET on bulk silicon substrate can relieve of the retention degradation because the channel boron doping can be reduced to more than one order compared to the conventional planar array FET.

Temperature Anisotropy Measurement Using Diamagnetic Loop Array

The anisotropy of the ion distribution function in the velocity space is observed in the ion cyclotron range of frequency heating experiments on the tandem mirror GAMMA 10. The anisotropy, defined as T⊥/T// (ratio of ion temperatures perpendicular and parallel to the magnetic field line), is evaluated quantitatively using three diamagnetic loops aligned in the direction of the magnetic field line. Depending on the anisotropy and the plasma pressure, fluctuations below the ion cyclotron frequency are excited. In terms of the quantitative estimation of the anisotropy, it is established clear that the parameter region in which the fluctuations are observed agrees well with a theoretically predicted region of the convectively unstable Alfven ion cyclotron mode.

Application of HfSiON to Deep-Trench Capacitors of Sub-45-nm-Node Embedded Dynamic Random-Access Memory

In this study, the potential of HfSiON as the node dielectric of deep-trench (DT) capacitors was investigated for the first time. It was found out that a uniform thickness and a uniform depth profile of each component in DT can be obtained by the ALD process which utilizes the catalytic effect of the Hf precursor and Si precursor. In addition, the mechanism underlying leakage current was analyzed and it was revealed that residual carbons in the film contribute to the Poole?Frenkel current through the film. On the basis of these findings, we propose the sequential high-pressure ozone treatment (SHO) and Al2O3/HfSiON/Si3N4 stack for DT applications. Finally, the DT capacitors of 65-nm-node embedded dynamic random-access memory (eDRAM) were fabricated and a capacitance enhancement of 50% from the conventional dielectric (NO) was obtained at the same leakage current.

Pitch-Angle Measurement of Ions by the Use of a Small Faraday Cup

The pitch-angle distribution of ions in the ICRF-heated plasma is measured using a small Faraday cup in the central cell of a GAMMA 10 tandem mirror. The pitch-angle distribution in the slow wave heating experiment shows the turning points of the mirror-trapped ion center into the ion cyclotron resonance layer. The temperature anisotropy defined by T⊥/T// is evaluated when the resonance layer is located near the midplane in the central cell of the GAMMA 10 tandem mirror.

Vertex channel array transistor (VCAT) featuring sub-60nm high performance and highly manufacturable trench capacitor DRAM

Novel vertex channel array transistor (VCAT) fabricated on bulk silicon substrate is applied to trench capacitor DRAM cell for the first time. VCAT utilizes the vertexes as channel between top surface and (111) facet of selective epitaxial Si on active areas. It can be fabricated with much simpler process than FIN array transistor reported previously and fit to the process integration of trench capacitor DRAM cell. Almost 2 times higher on-current, smaller sub-threshold swing and less body effect than a conventional planar array transistor are demonstrated.

Ab initio Molecular Orbital Study of Water Absorption and Hydrolysis of Chemical Vapor Deposited SiOF Films II

In part 1, we reported the mechanism of water absorption and hydrolysis of SiOF films theoretically using the ab initio molecular orbital (MO) method with small SiF n (OH) 4-n (n = 0-3) tetrahedral model clusters. It was revealed that the multiple F-substituted Si atoms had a higher reactivity against both OH- and H 2 O than Si atoms with one or no Si-F bonding. Also, defect sites such as non bridging oxygens (NBOs) and free spaces around Si-F bonding were proved to promote the hydrolysis and successive water adsorption. The structure required to initiate the hydrolysis reaction was the multiple F-substituted Si, in particular, = SiF 2 . In part 2, we attempt to show the possibility of suppressing the formation of = SiF 2 . The results of a Monte Carlo investigation corresponding to such as an F-ion implantation into SiO 2 suggested the possibility of achieving higher doping of F with suppression of the formation of SiF 2 by modulating the probability of F substitution into SiO 2 .

Suppression of Alfvén Ion Cyclotron Instability in a Mirror by End Plugging

The effect of end plugging of the ion on the Alfven ion cyclotron instability in a mirror-confined plasma is studied. The dispersion equation in the uniform-plasma approximation is derived by assuming a loss cone distribution of the ion, taking into account the end plugging, and is solved numerically. It is shown that the end plugging effect of filling the loss cone mainly causes the reduction of the temperature anisotropy of the ion, leading to the suppression of the instability.