Investigation of a New Disturb Effect in the Aggressively Scaled Dual-Bit/Cell Split-Gate Floating-Gate Flash Cell

A new disturb effect had been experimentally shown in an aggressively scaled triple self-aligned split-gate floating-gate (FG) NOR-type Dual-bit/cell (NORD) flash array. The mechanism of this new disturb was demonstrated and studied by a series of test experiments and the assistant of technology computer-aided-design (TCAD) simulation. It was revealed that non-suppressed disturb effect was ascribed by the hot electron injection, which originated from the strong electronic field and high current density in the substrate under the edge of disturbed FG. Based on the simulated result, we proposed a method of self-aligned etching shallow trench contact on bit line (BL) to suppress this new disturb effect. It was illustrated that the current density in the substrate under the edge of disturbed FG was effectively reduced, which fundamentally decreased the possibility of injection.