Self-aligned bit line under word line memory array

摘要

A memory device is described that comprises a plurality of bit lines and an array of vertical transistors arranged on the plurality of bit lines. A plurality of word lines is formed along rows of vertical transistors in the array which comprise thin film sidewalls of word line material and arranged so that the thin film sidewalls merge in the row direction, and do not merge in the column direction, to form word lines. The word lines provide surrounding gate structures for embodiments in which the vertical transistors are field effect transistors. Memory elements are formed in electrical communication with the vertical transistors. A fully self-aligned process is provided in which the word lines and memory elements are aligned with the vertical transistors without additional patterning steps.