Improvement of Line-to-line TDDB by Cu and Barrier-metal Recess Structure for high voltage circuit in 3D Flash Memory

Cu interconnect structure is investigated to improve TDDB property of Cu line-to-line with scaled pitch in high voltage circuit for 3D flash memory. Recessed Cu and barrier-metal structure reduce unexpected local electric field concentration, and suppress Cu
²⁺
or other cations drift into intra metal dielectrics. Those result in better reliability characteristics regarding TDDB life time than that of conventional structure.