Mechanism of moisture uptake induced via failure and its impact on 45nm node interconnect design

Abstract

Moisture induced via failure (MIVF) is studied for 45nm interconnect technology using porous low-k films. Test patterns are designed to examine the layout dependence of the MIVF. Some fundamental and important layout dependencies of the via resistance increase are investigated and considered for the first time. It has been found that the MIVF has not been suppressed, even though multiple vias structure is adopted. On the contrary, local wiring pattern density close to via and dummy wiring pattern area size strongly affect via resistance increase. A model with moisture ventilation can successfully explain those layout dependencies. It is confirmed that the MIVF is completely suppressed by the control of dummy pattern layout