US Patent 7560762 Asymmetric floating gate NAND flash memory

A NAND-type flash memory device includes asymmetric floating gates overlying respective wordlines. A given floating gate is sufficiently coupled to its respective wordline such that a large gate (i.e., wordline) bias voltage will couple the floating gate with a voltage which can invert the channel under the floating gate. The inversion channel under the floating gate can thus serve as the source/drain. As a result, the memory device does not need a shallow junction, or an assist-gate. In addition, the memory device exhibits relatively low floating gate-to-floating gate (FG-FG) interference.