Three-dimensional semiconductor memory devices
Three-dimensional (3D) nonvolatile memory devices include a substrate having a well region of second conductivity type (e.g., P-type) therein and a common source region of first conductivity type (e.g., N-type) on the well region. A recess extends partially (or completely) through the common source region. A vertical stack of nonvolatile memory cells on the substrate includes a vertical stack of spaced-apart gate electrodes and a vertical active region, which extends on sidewalls of the vertical stack of spaced-apart gate electrodes and on a sidewall of the recess. Gate dielectric layers extend between respective ones of the vertical stack of spaced-apart gate electrodes and the vertical active region. The gate dielectric layers may include a composite of a tunnel insulating layer, a charge storage layer, a relatively high bandgap barrier dielectric layer and a blocking insulating layer having a relatively high dielectric strength.
1. A nonvolatile memory device, comprising:
a substrate having a first region of first conductivity type therein and a second region of second conductivity type on the first region;
a recess region in the substrate, the recess region extending into the second region; and
a plurality of stack-structures of nonvolatile memory cells spaced apart on the substrate, each of the stack-structures comprising:
a plurality of gate patterns vertically spaced apart from one another on the substrate;
a vertical active pattern extending through each of the stack-structures across from the gate patterns and extending into the recess region; and
a gate dielectric layer extending between the gate patterns and the vertical active pattern;
wherein the second region is a common source region and extends between at least two vertical active patterns included in directly adjacent ones of the plurality of stack-structures.
2. The memory device of claim 1 , wherein the recess region extends through the second region, and
wherein a bottom surface of the recess region is lower than a bottom surface of the second region.
3. The memory device of claim 1 , wherein the plurality of stack-structures are spaced apart from one another extend in a first direction which is parallel with an upper surface of the substrate, and
wherein the second region extends in the first direction.
4. The memory device of claim 1 , wherein respective vertical active patterns included in the plurality of stack-structures are spaced apart from each other in a first direction and in a second direction perpendicular to the first direction, and
wherein the second region extends in the first and second directions.
5. The memory device of claim 1 , wherein the gate patterns overlap with the second region when viewed from a plan view.
6. The memory device of claim 1 , wherein the gate dielectric layer comprises a tunnel dielectric layer adjacent to the vertical active pattern, a blocking dielectric layer adjacent to the gate pattern, and a charge storage layer between the tunnel dielectric layer and the blocking dielectric layer.
7. The memory device of claim 1 , wherein the gate dielectric layer horizontally extends and covers a lower surface and an upper surface of a respective gate pattern.
8. The memory device of claim 1 , further comprising:
a protective dielectric layer provided on a sidewall of the recess region, wherein the protective dielectric layer extends between the vertical active pattern and the common source region.
9. The memory device of claim 1 , wherein the vertical active pattern comprises a lower active pattern filling the recess region and an upper active pattern having a cylindrical shape on the lower active pattern.
10. The memory device of claim 9 , wherein the lower active pattern contacts the first region and the second region.
11. The memory device claim 9 , wherein the lower active pattern has a non-planar upper surface that is higher than an upper surface of the substrate.