Shrinkable Triple Self-Aligned Field-Enhanced Split-Gate Flash Memory

Abstract

This paper demonstrates a shrinkable triple self-aligned split-gate flash cell fabricated using a standard 0.13-/spl mu/m copper interconnect process. The approach used here to create a self-aligned structure is to form a spacer against the prior layer. Due to a higher aspect ratio when the cell pitch decreases, the profile of the spacer structure becomes sharper. This improves process control of the spacer profile and length. All the processes used here are compatible with standard logic process. The word line channel length of the cell is 0.11 /spl mu/m. It is comparable in area with a stacked-gate cell and can be less than 13F/sup 2/. The cell is erased by using poly-poly Fowler-Nordheim tunneling with a sharp floating-gate edge to increase the electric field, and is programmed by source-side injection. As a result, this cell is highly suitable for low power applications and embedded products. Characterization shows considerable program and erase speed, up to 300 K times cycling endurance, and excellent disturb margins.