| The properties of electrically active defects in thermally grown SiO(,2) film, at the SiO(,2)/Si interface, and in the silicon surface space-charge layer of a silicon metal-oxide-semiconductor structure were studied by avalanche injection and KeV electron irradiation. Three donorlike defects were identified: the bulk compensating donor in silicon (the boron acceptor deactivation effect), the donorlike interface density-of-state peak at E(,I) + 0.3 eV, and the positive turn-around charge in the SiO(,2)/Si interfacial region. The atomic models of these defects were investigated by the dependencies of their generation and annealing kinetics on the gate materials and the process conditions.; All the results from a set of systematically designed experiments are consistent with a proposed model based on hydrogen. This model contains four important steps: (1) The release of atomic hydrogen from SiO-H and Si-H bonds in the bulk SiO(,2) and at the SiO(,2)/Si interface, as well as from AlO-H and Al-H bonds at the Al-SiO(,2) interface by ionizing radiation or energetic electrons or holes; (2) The migration of the atomic hydrogen across the oxide toward the silicon substrate or poly-Si gate by a multiple bond-breaking, diffusion, and bond-forming processes; (3) The modification of the SiO(,2)/Si interfacial bonds by atomic hydrogen, which gives the buildup and reduction of the donorlike interface density-of-state peak and the positive turn-around charge; and (4) The deactivation of the substitutional boron acceptor in the silicon surface space-charge layer by interstitial atomic hydrogen with the formation of a B('-)H('+) or BH pair.; The effects of these donorlike defects on the endurance and reliability of silicon MOS devices were discussed and illustrated by examples. Methods of improving device reliability and endurance were suggested. |
