Extended abstract of a paper presented at Microscopy and Microanalysis 2012 in Phoenix, Arizona, USA, July 29 – August 2, 2012.

For the gate last approach of a high K metal gate scheme used in advanced CMOS technology, various materials were tested as wetting layers to allow Aluminum (Al) gap fill at gate widths of10 to 45 nanometers. In this study, Titanium (Ti) and Cobalt (Co) were investigated as a wetting layer for Al gap fill. It was discovered that Al-Ti and Al-Co alloys were formed during high temperature Al deposition. Alloys were characterized using XRD. Alloy’s impacts on line resistivity and subsequent Al Chemical Mechanical Polish (Al CMP) were also investigated. In addition, a model was established to predict the alloy type and alloy mole% with respect to feature size. The predicted Al mole% by this model correlated very well with 1) line resistivity trend and 2) morphologies. The model also predicted that due to Al lower electro-chemical potential than Ti, Co or its alloys, galvanic corrosion could take place depending on the chemical environment in the Al CMP slurry. Different slurry or cleaning chemical may reduce or increase the risk of galvanic corrosion. The knowledge gained with the help of the model provides clear directions on selection criteria for wetting layers, optimization for deposition processes and Al CMP consumable design to meet the challenges.

Shock reflections over a convex and a concave wedge were investigated by using a 5 × 7 cm ordinary pressure-driven shock tube. Dry air was used for both the driving and driven gases. The large difference between the transition from regular (RR) to Mach reflection (MR) and that from MR to RR was observed, confirming the results obtained by Ben-Dor, Takayama & Kawauchi (1980). These results contradict all of the previous theoretical transition criteria. A new theory on the transition between RR and MR was developed by applying Whitham's ‘ray shock’ theory. This new theory agrees quite well with the experimental results.

A new magneto-optical (MO) imaging system for high-throughput characterization of combinatorial magnetic thin films has been developed. The instrument allows us to measure both Faraday rotation and ellipticity maps at various wavelengths (400 nm∼1000 nm), different magnetic fields (0∼2000 G), and different temperatures (12 K∼300 K) for wide variety of materials. We used the magnetic circular dichroism (MCD) modulation technique to map MO properties, relatively free from substrate effects. The superiority of this system is that magnetic hysteresis curves of numerous specimens with different compositions prepared by the combinatorial technique can be simultaneously measured at one sweep of magnetic field, providing an efficient characterization method for combinatorial magnetic materials. We also confirmed that the system possesses enough spatial resolution and sensitivity for detecting MO signals of individual pixels contained in a combinatorial library.

A combinatorial material synthesis with temperature gradient heating system was employed to optimizing growth parameters for oxide growth on Si substrate. From the obtained results, it was found the dielectric property depends on the growth temperature as well as the composition. The interface structures were investigated by high resolution electron microscopy with a series of specimens fabricated by micro sampling method. The results showed that amorphous oxide region and SiO2 layer were formed at the interface. It was speculated that the amorphous oxide region contributed to the reduction of the dielectric property. To avoid the amorphous and SiO2 formation at the oxide/Si interface, a few kinds of intermediate layers were inserted and tested to find the possibility of abrupt interface formation.

Magnetic films for miniaturization of planar inductors operating at GHz frequencies require high resistivity and high ferro-magnetic resonance frequency. Y type magnetoplumbite Ba2Co2Fe12O22(Co2Y) is a candidate material to meet such requirements because it has about 10 &m resistivity and resonance frequency higher than 2 GHz. Recently we succeeded in the fabrication of Co2Y epitaxial thin film on MgAl2O4 substrate by combinatorial pulsed laser deposition technique [3]. Here, we report on the magnetic and dielectric properties of this film. The DC resistivity of the film was 7.5 &m. The dielectric constant at 1.25 GHz was measured by a microwave microscope to be 11.0. An easy axis coercive force and saturation magnetization were about 145 Oe and 2000 Gauss respectively, being close to those of bulk sample. Furthermore, the magnetic micro domain structures of Co2Y epitaxial thin films were observed by a scanning SQUID microscope.

The realization of a trivalent ion conduction in solids was successful by selecting the Sc2(WO4)3-type structure from the consideration of the mobile trivalent cations and the structure which decreases the electrostatic interaction between the migrating trivalent ionic species and the framework structure as much as possible. Among the rare earth tungstates, Sc2(WO4)3 (σ600°C=6.5× 10−5 S'cm−1, Ea=44.1 kJ.mo−1) was found to hold the most suitable size for the trivalent ion migration in the relation between the mobile ion size and the lattice volume. The ion conducting characteristics of rare earths were studied by means of both the polarization and dc electrolysis techniques. The mobile species was demonstrated to be the trivalent ions in the Sc2(WO4)3-type structure. By the dc electrolysis, the mobile ion species was definitely identified to be the trivalent ions in the Sc2(WO4)3-type tungstates. In addition, the demonstration of a macroscopic Al3+ ion conduction in the tungstate structure was directly accomplished.

A single high Tc phase of Bi-Pb-Sr-Ca-Cu-O superconductor was obtained by following proper synthetic conditions:(a)addition of Pb, (b)proper starting composition, (c)codecomposition method, (d)sintering under low oxygen partial pressure and (e)long sintering. The composition analysis showed that every atomic site might be occupied by some element and there might not be defects or excess atoms in the structure. The hole donor in these samples is considered to be Pb on the Bi site and hole concentration seems to be, to some extent, controlled by the Pb content. A phase with four CuO2 layers have possibly grown on the surface of the grains of thi high Tc phase.