Yasuhiro Kimura

Femtosecond Dynamics of Nonresonant Third-Order Optical Nonlinearity of 1-(3-thienyl)-3-(4-chlorophenyl)propene-1-one Crystal and Solution

For the crystal and solution of 1-(3-thienyl)-3-(4-chlorophenyl)propene-1-one (TCPP), which is transparent over the whole visible region, the nonresonant third-order nonlinear dynamics is investigated by time-resolved degenerate four-wave mixing spectroscopy. The temporal nonlinear behaviors of both crystal and solution exhibit the instantaneous responses during 80 fs excitation at around 625 nm. The third-order nonlinear susceptibilities are determined to be |χ(3)bbbb| = 7.1 ×10-13 esu for crystal and |χ (3)TC1111| = 7.1 ×10-14 esu at 1 mol/l for solution. This suggests that the TCPP crystal has a large value of χ(3)/ατ= 2.4 ×103 esucms-1 under the assumption of the nonlinear response time τ= 30 fs (absorption coefficient α= 0.01 cm-1), which is a parameter important for ultrafast optical control materials. The obtained |χ(3)bbbb| value satisfies an already known relationship between the second- and third-order susceptibilities.

Analyzing electromigration near a right-angled corner composed of dissimilar metals by investigating the effect of material combination on atomic flux divergence

Atomic flux divergence (AFD) near a right-angled corner composed of dissimilar metals is theoretically analyzed in the present paper. A basic model of layered interconnect lines involving a right-angled corner is constructed. A two-dimensional electromigration (EM) problem near the corner is analyzed by treating the angled line as a single-crystal line without a passivation layer and with a uniform width. The material combination was found to play a significant role in determining the amount of AFD that occurs near the corner. The analysis of AFD in the present paper provides a unique insight into EM from the viewpoint of AFD singularities governed by the material combination. In addition, in terms of EM reliability issues in interconnects, several countermeasures for reducing the EM-induced damage are proposed.

Buried structure for increasing fabrication performance of micromaterial by electromigration

The electromigration (EM) technique is a physical synthetic growth method for micro/nanomaterials. EM causes atomic diffusion in a metal line by high-density electron flows. The intentional control of accumulation and relaxation of atoms by EM can lead to the fabrication of a micro/nanomaterial. TiN passivation has been utilized as a component of sample in the EM technique. Although TiN passivation can simplify the cumbersome processes for preparing the sample, the leakage of current naturally occurs because of the conductivity of TiN as a side effect and decreases the performance of micro/nanomaterial fabrication. In the present work, we propose a buried structure, which contributes to significantly decreasing the current for fabricating an Al micromaterial by confining the current flow in the EM technique. The fabrication performance was evaluated based on the threshold current for fabricating an Al micromaterial using the buried structure and the previous structure with the leakage of current.

Evaluation of electromigration near a corner composed of dissimilar metals by analyzing atomic flux at the interface

This research evaluates the electromigration (EM)-induced damage at the interface near a right-angled corner, which is composed of dissimilar metals in a single-crystal line without passivation layer. The atomic flux at the interface is analyzed, and the effect of material combination on the accumulation or depletion of atoms is investigated. Ways for reducing the EM-induced damage are proposed, and are discussed in comparison with those reported in our previous work, where the countermeasures were deduced by analyzing the atomic flux divergence near the right-angled corner except for the interface.

Trial fabrication of Al micro-materials by electromigration using buildup structure

The present research shows the trial fabrication technique for huge production of Al micro-materials by electromigration (EM) using a buildup structure. The objective of this study is provision of inspiring notable structure to overcome disadvantage that is low throughput production using EM technique. The fabrication of micro-materials using the presented buildup structure is partly demonstrated in this study. This study shows the dependence of fabrication of micro-materials on the conditions of holes introduced for discharging atoms, and potential for high throughput production.

Use of CrN Passivation for Fabricating Al Micro-Materials by Electromigration

The technique for fabricating Al micro-materials using a conductive passivation film by electromigration (EM), which is the physical phenomenon of atomic transport with high-density electron flow, has been reported. Conductive passivation film precludes the unplanned hillock formation and substantially simplifies the sample preparation time for fabricating Al micro-materials by EM. To date, TiN that is electrical conductive material has been used as a passivation film. However, the TiN passivation oxidizes during heat and current test for fabricating Al micro-materials by EM because of inherent poor oxidation resistance of TiN. Oxidation of passivation causes a problem that applying current occasionally becomes difficult. The present paper proposes a new conductive passivation made of CrN for fabricating Al micro-materials by EM. CrN is used as a countermeasure against the oxidation problem. Additionally, the growth of Al micro-materials by EM is investigated in the relation with the experimental conditions of current and substrate temperature. As a result, we report that the fabrication of Al micro-materials using the CrN passivation is successfully demonstrated in the relation with the experimental conditions.