A memory circuit having dual-gate memory cells and a method for
fabricating such a memory circuit are disclosed. The dual-gate memory
cells each include a memory device and an access device sharing a
semiconductor layer, with their respective channel regions provided on
different surfaces of the semiconductor layer. The semiconductor layer
has a thickness, such that when a pass voltage is applied to the gate
electrode of the access device, the access device and the memory device
remains isolated, such that the charge stored in the memory device is
unaffected by the pass voltage. The pass voltage is determined from a
range of voltages, when applied to the access device, has no effect on
the threshold voltage of the memory device. The dual-gate memory cells
can be used as building blocks for a non-volatile memory array, such as a
memory array formed by NAND-strings. In such an array, during programming
of a nearby memory device in a NAND string, in NAND-strings not to be
programmed, if inversion regions are allowed to be formed in the
semiconductor layer, or if the semiconductor layer is allowed to
electrically float, electrical interaction exists between the access
devices and the memory devices to inhibit programming of the memory
devices.