Atomic Displacement Effects in Single-Event Gate Rupture.

Swift heavy ion (SHI) damage, including single-event gate rupture (SEGR), radiation-induced soft breakdown (RISB), and long-term reliability degradation (LTRD), plays an important role in limiting device lifetime and reliability. However, the atomic-scale physical origins of these phenomena have not been elucidated. In this work, we explain the underlying physical processes responsible for SHI-induced effects in oxides, providing a direct link between atomic motion and macroscopic electrical effects. SRIM 2008 calculations show that SHIs produce low-energy atomic recoils in SiO2. Using parameter-free quantum mechanical calculations, we probe the atomic-scale dynamics of the resulting low-energy atomic displacements. We show that low-energy displacements in SiO2 produce pockets containing high densities of network defects, and that these defects generate electronic states throughout the SiO2 band gap. These spatially correlated defect states represent a low-resistivity ldquoconducting piperdquo through SiO2 layers, and provide an atomistic mechanism for the formation of electrically-active damage that does not rely on thermal spike effects. In the case of SEGR, the conducting pipe allows energy stored on the gate capacitance to be discharged into the oxide, resulting in the permanent damage observed experimentally. The persistence of defects resulting from SHI-induced atomic displacements provides a physical explanation for percolation models of LTRD and RISB. [ABSTRACT FROM PUBLISHER]