High Density Split-Gate Memory Cell

摘要

A method of forming a memory device that includes forming on a substrate, a first insulation layer, a first conductive layer, a second insulation layer, a second conductive layer, a third insulation layer. First trenches are formed through third insulation layer, the second conductive layer, the second insulation layer and the first conductive layer, leaving side portions of the first conductive layer exposed. A fourth insulation layer is formed at the bottom of the first trenches that extends along the exposed portions of the first conductive layer. The first trenches are filled with conductive material. Second trenches are formed through the third insulation layer, the second conductive layer, the second insulation layer and the first conductive layer. Drain regions are formed in the substrate under the second trenches. A pair of memory cells results, with a single continuous channel region extending between drain regions for the pair of memory cells.

主权项

1. A method of forming a memory device, comprising:
forming a plurality of separated first trenches into a surface of a semiconductor substrate, wherein the first trenches are parallel to each other and extend in a first direction and define active regions of the substrate between the first trenches; filling the first trenches with insulation material; forming a first insulation layer on the surface of the substrate in each of the active regions; forming a first conductive layer on the first insulation layer in each of the active regions; forming a second insulation layer on the first conductive layer in each of the active regions; forming a second conductive layer on the second insulation layer in each of the active regions; forming a third insulation layer on the second conductive layer in each of the active regions; forming a plurality of separated second trenches through the third insulation layer, wherein the second trenches are parallel to each other and extend in a second direction perpendicular to the first direction; extending the second trenches through the second conductive layer and the second insulation layer; extending the second trenches through the first conductive layer, leaving side portions of the first conductive layer exposed; forming a fourth insulation layer at the bottom of the second trenches that extends along the exposed portions of the first conductive layer; filling the second trenches with conductive material, wherein the conductive material is insulated from the substrate surface and the first conductive layer by the fourth insulation layer; forming a plurality of third trenches through the third insulation layer, wherein the third trenches are parallel to each other and extend in the second direction such that the second and third trenches alternate each other; extending the third trenches through the second conductive layer, the second insulation layer, and the first conductive layer; performing an implantation to form drain regions in the substrate under the third trenches.