Method for forming memory array bitlines comprising epitaxially grown silicon and related structure

Abstract

According to one exemplary embodiment, a method of fabricating a bitline in a memory array includes forming a trench in a substrate, where the trench has sidewalls and a bottom surface. The method further includes performing a selective epitaxial process to partially fill the trench with selective epitaxially grown silicon, where the selective epitaxially grown silicon is situated on the sidewalls and bottom surface of the trench. The selective epitaxially grown silicon is doped in the selective epitaxial process. The method further includes performing a silicon reflow process to cause the selective epitaxially silicon to be redistributed in the trench. The method further includes performing a number of selective epitaxial process/silicon reflow process cycles to substantially fill the trench with the selective epitaxially grown silicon. The method further includes extending a top surface of the selective epitaxially grown silicon in the trench above an ONO stack to form the bitline.