Hideki Hosokawa

Preferred Orientation in Ti Films Sputter-Deposited on SiO2 Glass: The Role of Water Chemisorption on the Substrate

Ti thin films have been grown on SiO2 glass layers at 350°C by ultrahigh vacuum magnetron sputtering with a small amount of H2O, H2 or O2 gas introduction to investigate the influence of adsorption on the crystallographic orientation of the Ti films. In situ reflection high-energy electron diffraction (RHEED) and ex situ X-ray diffraction (XRD) studies showed that a water vapor introduction at the beginning of sputter deposition promotes a highly preferred (002) orientation, whereas H2 gas or O2 gas introduction does not affect the orientation. These results indicate that the increase of water chemisorption on the substrate by H2O gas introduction and reduction of the surface free energy enhance the self-assembly of the Ti atoms toward the most stable C-axis orientation.

Effect of water absorption of dielectric underlayers on crystal orientation in Al–Si–Cu/Ti/TiN/Ti metallization

The influence of the exposure of underlying dielectric (phophosilicate glass and borophosphosilicate glass) films to a humid air ambient on crystallographic orientations in Al–Si–Cu/Ti/TiN/Ti layered structures has been investigated as a function of the boron content and exposure time of the dielectric films. The Al(111) orientation in the layered structures was found to improve drastically with increasing boron content and exposure time of the dielectric films. The full width at half maximum value of an Al(111) x-ray rocking curve reached less than 1°. It was also found that the Al–Si–Cu surface becomes smoother and the average grain size increases as the Al(111) orientation improves. The improved Al(111) orientation was attributed to the improved Ti(002) orientation of the bottom Ti films. The mechanism of the improved Ti(002) orientation was investigated. It was confirmed that the improved orientation is closely related with the surface concentration of the absorbed water in the dielectric films. Further, it was demonstrated that interconnects fabricated from the improved layered structure have excellent electromigration performance.The influence of the exposure of underlying dielectric (phophosilicate glass and borophosphosilicate glass) films to a humid air ambient on crystallographic orientations in Al–Si–Cu/Ti/TiN/Ti layered structures has been investigated as a function of the boron content and exposure time of the dielectric films. The Al(111) orientation in the layered structures was found to improve drastically with increasing boron content and exposure time of the dielectric films. The full width at half maximum value of an Al(111) x-ray rocking curve reached less than 1°. It was also found that the Al–Si–Cu surface becomes smoother and the average grain size increases as the Al(111) orientation improves. The improved Al(111) orientation was attributed to the improved Ti(002) orientation of the bottom Ti films. The mechanism of the improved Ti(002) orientation was investigated. It was confirmed that the improved orientation is closely related with the surface concentration of the absorbed water in the dielectric films. Furth...

Influence of water absorption of dielectric underlayers on Al(111) crystallographic orientation in Al-Si-Cu/Ti/TiN/Ti layered structures

The influence of the exposure of underlying dielectric (phosphosilicate glass [PSG] and borophosphosilicate glass [BPSG]) films to a humid air ambient on crystallographic orientations in AlSi-Cu/Ti/TiN/Ti layered structures has been investigated as a function of the boron content and exposure time of the dielectric films. The Al( 11 1) orientation in the layered structures was found to improve drastically with increasing boron content and exposure time of the dielectric films. The full width at half maximum (FWHM) value of an Al( 11 1) x-ray rocking curve reached less than 1 degree. It was also found that the Al-Si-Cu surface becomes smoother and the average grain size increases as the Al( I1 1) orientation improves. The improved Al( 1 1 1) orientation was attributed to the improved Ti(002) orientation of the bottom Ti films. The mechanism of the improved Ti(002) orientation was investigated. It was confirmed that the improved orientation is closely related with the surface concentration of the absorbed water in the dielectric films. Further, it was demonstrated that interconnects fabricated from the improved layered stmcture have excellent electromigration performance.

Modeling of common-mode noise generated by motor control unit on vehicle

In this paper, we propose a circuit model that can predict the common-mode noise current in the AM radio band that will flow to an evaluation circuit consisting of a DC motor, a motor control unit, and a battery. In this model, the common-mode impedance of each unit and the impedance of the cables are expressed by lumped constant circuits. It is found that the common-mode current that flows in the ground plate concentrates just below the cables, so the path of the current is also modeled by a lumped parameter circuit. We demonstrate that this model can predict the common-mode current in this system to within 6 dB. This model is expected to be an effective method for quantitatively predicting the noise suppression effect of a motor control unit for a vehicle.