Three-dimensional semiconductor memory devices

1. A three-dimensional (3D) semiconductor memory device comprising:

a source structure on a horizontal semiconductor layer, the source structure comprising a first source conductive pattern and a second source conductive pattern which are sequentially stacked on the horizontal semiconductor layer;

an electrode structure comprising a plurality of electrodes vertically stacked on the source structure; and

a vertical semiconductor pattern penetrating the electrode structure, the second source conductive pattern and the first source conductive pattern,

wherein a first portion of a sidewall of the vertical semiconductor pattern is horizontally spaced apart from the second source conductive pattern,

wherein a second portion of the sidewall of the vertical semiconductor pattern is in contact with the first source conductive pattern,

wherein the first source conductive pattern includes a discontinuous interface at a level between a top surface of the horizontal semiconductor layer and a bottom surface of the second source conductive pattern, and

wherein the discontinuous interface is enclosed by the first source conductive pattern.

2. The 3D semiconductor memory device of claim 1 ,

wherein the discontinuous interface is spaced apart from the top surface of the horizontal semiconductor layer by a first distance and is spaced apart from the bottom surface of the second source conductive pattern by a second distance different from the first distance.

3. The 3D semiconductor memory device of claim 1 ,

wherein the discontinuous interface is closer to the top surface of the horizontal semiconductor layer than to the bottom surface of the second source conductive pattern.

4. The 3D semiconductor memory device of claim 1 ,

wherein a distance between the discontinuous interface and the top surface of the horizontal semiconductor layer is equal to a distance between the discontinuous interface and the bottom surface of the second source conductive pattern.

5. The 3D semiconductor memory device of claim 1 ,

wherein the discontinuous interface is laterally spaced apart from the vertical semiconductor pattern.

6. The 3D semiconductor memory device of claim 1 ,

wherein the first source conductive pattern comprises:

a lower portion adjacent to the top surface of the horizontal semiconductor layer;

an upper portion adjacent to the bottom surface of the second source conductive pattern; and

a sidewall portion surrounding the second portion of the sidewall of the vertical semiconductor pattern and extending from an upper surface of the upper portion to a region between the second source conductive pattern and the vertical semiconductor pattern,

wherein the sidewall portion is interposed between the second source conductive pattern and the vertical semiconductor pattern.

7. The 3D semiconductor memory device of claim 6 ,

wherein the first source conductive pattern includes a semiconductor material doped with charge carrier impurities, and

wherein the lower portion and the upper portion have different crystal structures from each other in the first source conductive pattern.

8. The 3D semiconductor memory device of claim 6 ,

wherein the first source conductive pattern includes a semiconductor material doped with charge carrier impurities, and

wherein the lower portion and the upper portion have the same crystal structure in the first source conductive pattern.

9. The 3D semiconductor memory device of claim 6 ,

wherein the horizontal semiconductor layer includes single-crystalline silicon or poly- crystalline silicon, and

wherein the lower portion of the first source conductive pattern includes amorphous silicon or single-crystalline silicon.

10. The 3D semiconductor memory device of claim 6 ,

wherein the upper portion of the first source conductive pattern includes amorphous or poly-crystalline silicon, and

wherein the second source conductive pattern includes poly-crystalline silicon.

11. The 3D semiconductor memory device of claim 6 ,

wherein the bottom surface of the second source conductive pattern is vertically spaced apart from the top surface of the horizontal semiconductor layer by a first distance, and

wherein one sidewall of the second source conductive pattern is horizontally spaced apart from one sidewall of the vertical semiconductor pattern by a second distance less than the first distance.

12. The 3D semiconductor memory device of claim 1 ,

wherein the first and second source conductive patterns include a semiconductor material doped with charge carrier impurities having a first conductivity type, and

wherein a concentration of the charge carrier impurities in the first source conductive pattern is greater than a concentration of the charge carrier impurities in the second source conductive pattern.

13. The 3D semiconductor memory device of claim 1 , further comprising:

a source plug disposed on sidewalls of the electrode structure and the source structure and connected to the horizontal semiconductor layer; and

an insulating spacer disposed between the source plug and the electrode structure,

wherein the discontinuous interface is laterally spaced apart from the vertical semiconductor pattern and the source plug.

14. The 3D semiconductor memory device of claim 1 , further comprising:

a data storage pattern vertically extending between the vertical semiconductor pattern and the electrode structure,

wherein a bottom surface of the data storage pattern is in contact with a portion of the first source conductive pattern.

15. The 3D semiconductor memory device of claim 14 ,

wherein the bottom surface of the data storage pattern is located at a level between a bottom surface of a lowermost one of the electrodes and the bottom surface of the second source conductive pattern.

16. A three-dimensional (3D) semiconductor memory device comprising:

a source structure on a horizontal semiconductor layer, the source structure comprising a first source conductive pattern and a second source conductive pattern which are sequentially stacked on the horizontal semiconductor layer;

an electrode structure comprising a plurality of electrodes stacked on the source structure; and

a vertical semiconductor pattern penetrating the electrode structure, the second source conductive pattern and the first source conductive pattern in a direction perpendicular to a top surface of the horizontal semiconductor layer,

wherein a first portion of a sidewall of the vertical semiconductor pattern is horizontally spaced apart from the second source conductive pattern,

wherein a second portion of the sidewall of the vertical semiconductor pattern is in contact with the first source conductive pattern of the source structure,

wherein the first source conductive pattern comprises:

a lower portion adjacent to a top surface of the horizontal semiconductor layer; and

an upper portion adjacent to a bottom surface of the second source conductive pattern,

wherein the upper portion and the lower portion have different crystal structures from each other.

17. The 3D semiconductor memory device of claim 16 ,

wherein the first source conductive pattern further comprises:

a sidewall portion which extends from the upper and lower portions in the direction perpendicular to the top surface of the horizontal semiconductor layer and surrounds the second portion of the sidewall of the vertical semiconductor pattern.

18. The 3D semiconductor memory device of claim 17 ,

wherein a top surface of the sidewall portion is located at a level between a bottom surface of a lowermost one of the electrodes and a top surface of the first source conductive pattern, and

wherein a bottom surface of the sidewall portion is located at a level between a bottom surface of the vertical semiconductor pattern and the top surface of the horizontal semiconductor layer.

19. The 3D semiconductor memory device of claim 16 ,

wherein the upper portion of the first source conductive pattern includes amorphous or poly-crystalline silicon, and the lower portion of the first source conductive pattern includes single-crystalline silicon.

20. The 3D semiconductor memory device of claim 16 ,

wherein the upper portion of the first source conductive pattern includes amorphous silicon, and the lower portion of the first source conductive pattern includes poly-crystalline silicon.