Three-dimensional semiconductor device, variable resistive memory device including the same, and method of manufacturing the same

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

a source formed of a first semiconductor material;

a channel layer formed on the source and formed of the first semiconductor material;

a lightly doped drain (LDD) region formed on the channel layer and formed of a second semiconductor material having a higher oxidation rate than that of the first semiconductor material;

a drain formed on the LDD region and formed of the first semiconductor material; and

a gate insulating layer formed on outer circumferences of the channel layer, the LDD region, and the drain.

2. The 3D semiconductor device of claim 1 , wherein the first semiconductor material is silicon.

3. The 3D semiconductor device of claim 2 , wherein the second semiconductor material is silicon germanium (SiGe).

4. The 3D semiconductor device of claim 1 , wherein a portion of the gate insulating layer, formed on the outer circumference of the LDD region, is thicker than portions of the gate insulating layer, formed on the outer circumferences of the channel layer and the drain.

5. The 3D semiconductor device of claim 1 , further comprising a gate formed to surround an outer circumference of the gate insulating layer.

6. The 3D semiconductor device of claim 5 , wherein the gate is formed to overlap the channel layer and a portion of the LDD region.

7. A variable resistive memory device, comprising:

a semiconductor device including a source formed of a first semiconductor material, a channel layer formed on the source and formed of the first semiconductor material, a lightly doped drain (LDD) region formed on the channel layer and formed of a second semiconductor material having a higher oxidation rate than that of the first semiconductor material, a drain formed on the LDD region and formed of the first semiconductor material, and a gate insulating layer formed on outer circumferences of the channel layer, the LDD region, and the drain; and

a resistive memory structure electrically coupled to the drain of the semiconductor device.

8. The variable resistive memory device of claim 7 , wherein the first semiconductor material is silicon.

9. The variable resistive memory device of claim 8 , wherein the second semiconductor material is silicon germanium (SiGe).

10. The variable resistive memory device of claim 7 , wherein a portion of the gate insulating layer, formed on the outer circumference of the LDD region, is thicker than portions of the gate insulating layer, formed on the outer circumferences of the channel layer and the drain.

11. The variable resistive memory device of claim 10 , wherein the semiconductor device further includes a gate formed on an outer circumference of the gate insulating layer, wherein the gate is formed to overlap the channel layer and a portion of the LDD region.

12. The variable resistive memory device of claim 8 , wherein the resistive memory structure includes:

a heating electrode formed on the drain; and

a resistance variable layer formed on the heating electrode.

13. The variable resistive memory device of claim 12 , wherein the resistance variable layer includes one selected from the group consisting of a PCMO layer for a resistive random access memory (ReRAM), a chalcogenide layer for a phase-change RAM (PCRAM), a magnetic layer for a magnetic RAM (MRAM), a magnetization reversal device layer for a spin-transfer torque magnetoresistive RAM (STTMRAM), and a polymer layer for a polymer RAM (PoRAM).