Vertical NAND flash memory device and method of manufacturing the same
A vertical NAND flash memory device and a method of manufacturing the same are provided. The vertical NAND flash memory device includes a charge trap layer arranged on an inner wall of a channel hole vertically formed on a substrate. The charge trap layer includes nanostructures distributed in a base. The nanostructures may include a material having a trap density of about 1×10 19 cm −3 to about 10×10 19 cm −3 , and the base may include a material having a conduction band offset (CBO) of about 0.5 eV to about 3.5 eV with respect to the material included in the nanostructures.
1 . A vertical NAND flash memory device comprising:
a substrate;
a structure on the substrate including a plurality of conductive layers arranged in parallel to an upper surface of the substrate, the structure including a channel hole formed vertical to the substrate and penetrating the of plurality of conductive layers;
a charge trap layer on an inner wall of the channel hole, the charge trap layer including a base and nanostructures distributed in the base; and
a channel layer on the charge trap layer, wherein
a material included in the nanostructures has a trap density of about 1×10 19 cm −3 to about 10×10 19 cm −3 , and
a material included in the base has a conduction band offset (CBO) of about 0.5 eV to about 3.5 eV with respect to the material in the nanostructures, wherein
the charge trap layer is formed by inducing spinodal decomposition through a heat treatment process on a mixture of the material included in the base and the material included in the nanostructures, and
the base has an amorphous structure after the spinodal decomposition is induced, and
the nanostructures have a crystalline structure or an amorphous structure after the spinodal decomposition is induced.
2 . The vertical NAND flash memory device of claim 1 , wherein the trap density of the material included in the nanostructures is about 2×10 19 cm −3 to about 5×10 19 cm −3 .
3 . The vertical NAND flash memory device of claim 1 , wherein the material included in the base has a higher band gap than the material included in the nanostructures.
4 . The vertical NAND flash memory device of claim 3 , wherein the CBO of the material included in the base is about 1.0 eV to about 2.0 eV with respect to the material included in the nanostructures.
5 . The vertical NAND flash memory device of claim 1 , wherein the nanostructures include at least one of SiN, GaN, GaO, HfO, ScO, SrO, ZrO, YO, TaO, BaO, and ZnS.
6 . The vertical NAND flash memory device of claim 5 , wherein the base includes at least one of SiO, AlO, MgO, AlN, BN, and GaN.
7 . The vertical NAND flash memory device of claim 6 , wherein a combination of the material included in the nanostructures and the material included in the base includes a combination of HfO and SiO, a combination of HfO and AlO, a combination of SiN and AlO, or a combination of ZrO and AlO.
8 . The vertical NAND flash memory device of claim 1 , wherein a size of the nanostructures is about 1 nm to about 20 nm.
9 . The vertical NAND flash memory device of claim 8 , wherein the size of the nanostructures is about 3 nm to about 5 nm.
10 . The vertical NAND flash memory device of claim 1 , wherein a gap between the nanostructures is about 2 nm to about 25 nm.
11 . The vertical NAND flash memory device of claim 10 , wherein the gap between the nanostructures is about 2 nm to about 10 nm.
12 . The vertical NAND flash memory device of claim 1 , wherein a ratio of a volume of the nanostructures in the charge trap layer to a volume of the charge trap layer is about 15% to about 75%.
13 . The vertical NAND flash memory device of claim 12 , wherein the ratio of the volume of the nanostructures in the charge trap layer to the volume of the charge trap layer is about 25% to about 60%.
14 . The vertical NAND flash memory device of claim 1 , wherein the charge trap layer has a surface roughness that is equal to or less than about 2 nm root-mean-square (RMS).
15 . The vertical NAND flash memory device of claim 1 , wherein the nanostructures are buried in the base.
16 . The vertical NAND flash memory device of claim 1 , wherein at least one of the nanostructures is exposed from the base.
17 . The vertical NAND flash memory device of claim 1 , wherein a gap between the conductive layers is equal to or less than about 30 nm.
18 . The vertical NAND flash memory device of claim 1 , wherein
the structure on the substrate includes an insulating layer between the plurality of conductive layers, and
the insulating layer extends parallel to the substrate.
19 . The vertical NAND flash memory device of claim 1 , further comprising:
a barrier dielectric layer is between the charge trap layer and the plurality of conductive layers.
20 . The vertical NAND flash memory device of claim 19 , further comprising:
a tunneling dielectric layer between the charge trap layer and the channel layer.
21 . The vertical NAND flash memory device of claim 20 , further comprising:
a filling dielectric layer on an inner side of the channel layer, wherein
the filling dielectric layer fills the channel hole.
22 . A vertical NAND flash memory device comprising:
a substrate;
a plurality of conductive layers and a plurality of insulating layers alternately stacked on an upper surface of the substrate, the plurality of conductive layers and the plurality of insulating layers defining a channel hole extending in a vertical direction through the plurality of conductive layers and the plurality of insulating layers; and
a channel structure in the channel hole, the channel structure including a channel layer extending in the vertical direction, the channel structure including a plurality of nanostructures distributed in a base between the channel layer and a sidewall of the channel hole, and a material included in the plurality of nanostructures has a lower band gap compared to a material included in the base, wherein
the material included in the nanostructures has a trap density of about 1×10 19 cm −3 to about 10×10 19 cm −3 , and
a conduction band offset (CBO) of the material included in the base with respect to the material included in the nanostructures is about 0.5 eV to about 3.5 eV wherein
the channel structure includes a charge trap layer containing the plurality of nanostructures distributed in the base, and
the charge trap layer is formed by inducing spinodal decomposition through a heat treatment process on a mixture of the material included in the base and the material included in the nanostructures, and
the base has an amorphous structure after the spinodal decomposition is induced, and
the nanostructures have a crystalline structure or an amorphous structure after the spinodal decomposition is induced.
23 . The vertical NAND flash memory device of claim 22 , wherein
the plurality of nanostructures have at least one of a spherical shape, an oval shape, and a rod shape.
24 . The vertical NAND flash memory device of claim 22 , wherein
the material included in the plurality of nanostructures include at least one of SiN, GaN, GaO, HfO, ScO, SrO, ZrO, YO, TaO, BaO, and ZnS, and
the material included in the base includes at least one of SiO, AlO, MgO, AlN, BN, and GaN.
25 . The vertical NAND flash memory device of claim 22 , wherein the channel structure includes at least one of:
a barrier dielectric layer between the channel layer and plurality of nanostructures distributed in the base; and
a tunneling dielectric layer between the channel layer and plurality of nanostructures distributed in the base.
26 . The vertical NAND flash memory device of claim 22 , wherein
a surface roughness of the charge trap layer is equal to or less than about 2 nm RMS.