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We construct a D2-D8-D8 configuration in string theory, it can be described at low energy by two dimensional field theory. In the weak coupling region, the low energy theory is a nonlocal generalization of Gross-Neveu(GN) model which dynamically breaks the chiral flavor symmetry U(N f ) L × U(N f ) R at large N c and finite N f . However, in the strong coupling region, we can use the SUGRA/Born-Infeld approximation to describe the low energy dynamics of the system. Also, we analyze the low energy dynamics about the configuration of wrapping the one direction of D2 brane on a circle with anti-periodic boundary condition of fermions. The fermions and scalars on D2 branes get mass and decouple from the low energy theory. The IR dynamics is described by the QCD 2 at weak coupling. In the opposite region, the dynamics has a holographic dual description. And we have discussed the phase transition of chiral symmetry breaking at finite temperature. Finally, after performing T-duality, this configuration is related to some other brane configurations.

We investigated HfO2 etching characteristics in conventional Si gate etching chemistries, namely, CF4 and Cl2/HBr/O2-based chemistries. We obtained an adequate etch rate of 2.0 nm/min for both chemistries and a selectivity of 1.9 over SiO2 for Cl2/HBr/O2-based chemistry. We examined the etch rate dependence on source power, bias power, O2 flow rate, and Cl2 flow rate in the Cl2/HBr/O2 chemistry. It was clarified that a physical component is dominant in HfO2 etching in this chemistry. The possibilities of achieving a higher HfO2/SiO2 selectivity and of controlling the anisotropic/isotropic component in HfO2 patterning were also discussed. Moreover, it was clarified that the surface portion of the damaged layer created by the dry-etching step can be removed by a subsequent wet etching. Based on these results, the sub-100 nm patterning of poly-Si/HfO2 gate stacks was successfully demonstrated.

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We have investigated physical and electrical properties of Al2O3, HfO2, and their alloy films deposited on 300mm Si wafers by Atomic Layer Deposition (ALD). It is found that Al2O3 films are not crystallized even after the heat treatment of 1050°C, while HfO2 films are already crystallized even after a-Si deposition (530°C). The crystallization temperature can be higher by adding Al2O3 to HfO2. It is confirmed by in-plane XRD and plane views of TEM that HfAlOx films with lower Hf content (Hf/(Hf+Al) <30%) are amorphous without phase separation after annealing at 1050°C and 5sec. The dependences of equivalent oxide thicknesses (EOT) on the physical thicknesses of Al2O3, HfAlOx (Hf/(Hf+Al)∼22%), and HfO2 films in poly-silicon gate capacitors indicate that those dielectric constants k are ∼9, 14, and 23, respectively. The gate dielectric with EOT of 1.5nm and the leakage current density Jg of 3mA/cm2 can be fabricated with 2nm-thick HfAlOx (22%) film.

The thermal stability of a SiO2/Al2O3 dielectric stack under high-temperature annealing after poly-Si gate deposition was examined. An interface reaction occurs when the activation temperature is higher than the post deposition annealing temperature, which results in the reduction of the interfacial oxide layer and hence silicate formation. As a result, the characteristics of metal oxide semiconductor field effect transistors (MOSFETs), such as mobility, reliability, and the distribution of capacitance are severely degraded. The formation of a SiON interfacial layer is found to be effective in suppressing the interface reaction.