A new prediction method for oxide lifetime and its application to study dielectric breakdown mechanism

Highly reliable ultrathin gate oxides (<5 nm) are required to realize high performance MOS LSIs. In such oxides, the breakdown process consists of the partial-breakdown (p-BD) and the complete-breakdown (c-BD). The p-BD is also called as quasi-breakdown or soft-breakdown (s-BD). The time to breakdown is characterized by two specific times, time to p-BD and time to c-BD after p-BD, to retain a definition of thick oxide breakdown even in ultrathin oxides. Hence, it is important to predict these two times independently. We also reported that the A-mode stress induced leakage current (SILC) is a good monitor for indicating the time to p-BD, while we can determine the p-BD by the B-mode SILC. In this paper, a universal relationship between A-mode SILC and oxide lifetime is found, when the lifetime is defined as the time to p-BD. This relationship allows the development of a new prediction method for oxide lifetime. The field acceleration and activation energy of lifetime are further discussed using the new prediction method.