Modeling of Interconnect Dielectric Lifetime Under Stress Conditions and New Extrapolation Methodologies for Time-Dependent Dielectric Breakdown

Advanced microelectronics interconnect systems can have metal leads several hundred meters long with minimum metal to metal spacing of <100nm. The low-k dielectric between adjacent metal lines has a lower dielectric breakdown strength compared to gate oxides. Accelerated testing of the interconnect time-dependent dielectrics breakdown (TDDB) is required during the development of new technology nodes, to ensure the reliability of these systems. This paper presents simulations that show how actual line-to-line spacing variations influence test results such that they can predict too low product lifetime. In fact, it is argued here that one can adhere to a conservative model for the lifetime dependence on the electric field (such as the is-model) and still pass stringent reliability requirements if the accelerated breakdown test results distributions are interpreted correctly.