Formation of high density tungsten nanodots embedded in silicon nitride for nonvolatile memory application

In this letter, the formation of high density tungsten nanodots (W-NDs) embedded in silicon nitride via a self-assembled nanodot deposition is demonstrated. In this method, tungsten and silicon nitride are cosputtered in high vacuum rf sputtering equipment. The W-NDs with small diameters (1-1.5 nm) and high density (similar to 1.3x10(13)/cm(2)) were achieved easily by controlling W composition; this is the ratio of total area of W chips to that of silicon nitride target. The metal-oxide-semiconductor memory device was fabricated with high density W-NDs floating gate and high-k HfO(2) blocking dielectric. A wide range memory window (0-29 V) was obtained after bidirectional gate voltages sweeping with range of +/- 1-+/- 23 V. It is feasible to design the memory window with propriety power consumption for nonvolatile memory application.