Nonvolatile memory device with reduced floating gate and increased coupling ratio and manufacturing method thereof

摘要

A nonvolatile memory device with a reduced size floating gate and an increased coupling ratio is disclosed. The nonvolatile memory device includes two isolation structures protruding above a semiconductor substrate. Two dielectric spacers are disposed on a pair of opposing sidewalls of the two isolation structures. The two dielectric spacers are spaced from one another at a distance that defines a gate width which is beyond lithography limit. A tunnel dielectric and a floating gate are provided on substrate and confined between the two dielectric spacers. The floating gate has a smaller bottom surface area relative to its top surface area and has a surface substantially coplanar with a surface of the isolation structures. On the coplanar surface, an inter-gate dielectric and a control gate are provided. Optionally, a lightly doped region is provided beside the floating gate 118 and within the substrate. A manufacturing method for forming such memory device is also disclosed.