Semiconductor device with vertical channel transistor and method for fabricating the same
A method for fabricating a semiconductor device includes forming a plurality of semiconductor body lines in which a plurality of buried bit lines are buried, to be separated by a plurality of trenches, forming a filling layer that fills each of the plurality of trenches, forming a conductive layer over the plurality of semiconductor body lines and the filling layer, forming a plurality of semiconductor pillars over the plurality of semiconductor body lines by etching the conductive layer.
1. A method for fabricating a semiconductor device, comprising:
forming a plurality of semiconductor body lines in which a plurality of buried bit lines are buried, to be separated by a plurality of trenches;
forming a filling layer that fills each of the plurality of trenches;
forming a conductive layer over the plurality of semiconductor body lines and the filling layer; and
forming a plurality of semiconductor pillars over the plurality of semiconductor body lines by etching the conductive layer,
wherein the filling layer is formed by flowing upper portions of the plurality of semiconductor body lines through a thermal process.
2. The method according to claim 1 , wherein the plurality of semiconductor body lines, the filling layer and the plurality of semiconductor pillars comprise monocrystalline silicon.
3. The method according to claim 1 , wherein the forming of the plurality of semiconductor body lines in which the plurality of buried bit lines are buried comprises:
etching a semiconductor substrate to form the plurality of semiconductor body lines that are separated by a plurality of bulb-shaped trenches;
forming a plurality of preliminary bit lines that partially fill the plurality of bulb-shaped trenches; and
etching to partially remove portions of the plurality of preliminary bit lines and forming the plurality of buried bit lines that fill sidewalls of bulbs of the plurality of bulb-shaped trenches.
4. The method according to claim 3 , wherein the forming of the plurality of semiconductor body lines that are separated by the bulb-shaped trenches comprises:
etching the semiconductor substrate to form the plurality of preliminary semiconductor body lines that are separated by a plurality of preliminary trenches;
forming a plurality of sacrificial layer patterns that partially fill the plurality of preliminary trenches;
forming a plurality of spacers on upper sidewalls of the plurality of preliminary trenches;
removing the plurality of sacrificial layer patterns; and
etching the preliminary trenches by using the plurality of spacers as an etch barrier and forming the bulb-shaped trenches.
5. The method according to claim 1 , further comprising:
forming a dielectric layer that partially fills the trenches before the forming of the filling layer.
6. The method according to claim 1 , wherein the conductive layer is formed through epitaxial growth by using the plurality of semiconductor body lines and the filling layer as seeds.
7. The method according to claim 1 , wherein the forming of the plurality of the semiconductor pillars comprises:
forming a plurality of line-type preliminary semiconductor pillars by etching a conductive layer;
forming an interlayer dielectric layer that fills spaces between the plurality of preliminary semiconductor pillars; and
forming the plurality of semiconductor pillars by etching the interlayer dielectric layer and the plurality of preliminary semiconductor pillars.
8. A method for fabricating a semiconductor device, comprising:
etching a silicon substrate and forming a plurality of silicon body lines that are separated by a plurality of trenches;
forming a dielectric layer in the trenches to have a height lower than a height of the plurality of silicon body lines;
forming a filling silicon layer over the dielectric layer through a thermal process that allows silicon migration of the silicon body lines;
forming a silicon layer over the filling silicon layer and the plurality of silicon body lines; and
forming a plurality of silicon pillars over the plurality of silicon body lines by etching the silicon layer and the filling silicon layer, wherein the plurality of silicon pillars include channel regions of vertical channel transistors.
9. The method according to claim 8 , wherein the plurality of silicon body lines and the filling silicon layer comprise monocrystalline silicon.
10. The method according to claim 8 , wherein the filling silicon layer is formed through annealing under an atmosphere containing hydrogen.
11. The method according to claim 10 , wherein the annealing is performed by using a mixture of hydrogen and an inert gas.
12. The method according to claim 8 , further comprising:
cleaning the surfaces of the plurality of silicon body lines before the forming of the filling silicon layer.
13. The method according to claim 8 , wherein the silicon layer is formed through epitaxial growth.
14. The method according to claim 8 , wherein the forming of the plurality of silicon pillars comprises:
forming a plurality of line-type preliminary silicon pillars by etching the silicon layer;
forming an interlayer dielectric layer that fills spaces between the plurality of preliminary silicon pillars; and
forming the plurality of silicon pillars by etching the interlayer dielectric layer and the plurality of preliminary silicon pillars.
15. The method according to claim 8 ,
wherein the plurality of trenches comprise bulb-shaped trenches, and
wherein the method further comprises:
forming a plurality of preliminary bit lines that fill the bulb-shaped trenches after the forming of the plurality of silicon body lines; and
etching to partially remove portions of the plurality of preliminary bit lines and forming a plurality of bit lines that are buried in both sidewalls of the plurality of silicon body lines.
16. The method according to claim 8 , further comprising:
forming plurality of word lines on sidewalls of the plurality of silicon pillars; and
forming capacitors to be connected with upper portions of the plurality of silicon pillars.