Fluorine-free Word Line Molybdenum Process for Enhancing Scalability and Reliability in 3D Flash Memory

A state-of-the-art fluorine-free word line (WL) molybdenum (Mo) process has been established for future 3D flash memory. Application of Mo to WLs can accelerate scaling of cells in both the vertical and horizontal directions with lower RC delay and lower leakage failure rates compared to traditional tungsten. In addition to being fluorine-free, key attributes of the process are optimization of Mo recess by innovative chemical and improvement of Mo filling to remove oxygen residue in Mo voids. These techniques can extend the scaling limit of 3D flash memory.