Annealing behavior of thin gate oxide alter quasi-breakdown (QB) has been investigated. The res;lt implies that the QB leakage current is consisted, of two components: the enhanced tunneling due to locally thinned oxide at interface-damaged region and the conduction through a shortening path. The change of leakage current during annealing is a competitive process of changes of these two components - the recovery of interface damage and the expansion of the shortening path in bulk oxide. A unified model is proposed to explain the mechanism of conduction in QB. (C) 2000 Elsevier Science Ltd. All rights reserved.