The essential limitations on gate insulator are related to the exponentially increasing gate current as the thickness of the oxide is reduced, and the effect of this current on both the functionality and reliability of devices and circuits. Quantum mechanical (ab initio) calculations models can be used to simulate the formation of atomic defects of a realistic material structure. Density functional theory and Hartree Fock theory have been used to model and study the nature of point defects in crystalline and amorphous silica. The amorphous silica models have been generated using a combined classical and ab initio molecular dynamics simulation scheme. The nature of oxygen vacancies, the role of hydrogen species and self trapped holes in SiO2 have been investigated.
EMPA, Materials Science and Technology, Electronic/Metrology Laboratory, Dübendorf