Semiconductor device having buried bit line, and method for fabricating the same
A method for fabricating a semiconductor device includes forming at least one body having two sidewalls by vertically etching a semiconductor substrate, forming a protective layer having open parts that expose portions of the both sidewalls of the body, forming a buffer layer that fills the open parts, and forming a buried bit line in the body by siliciding the buffer layer and a portion of the body between the buffer layer.
1. A method for fabricating a semiconductor device, comprising:
forming at least one body having two sidewalls by etching a semiconductor substrate;
forming a protective layer having open parts that expose portions of the both sidewalls of the body;
forming a buffer layer that fills the open parts; and
forming a buried bit line in the body by siliciding the buffer layer and a portion of the body between the buffer layer,
wherein the forming of the buried bit line comprises:
forming a conductive layer over an entire surface including the buffer layer; and
performing annealing to silicide the conductive layer, the buffer layer and the body.
2. The method of claim 1 , wherein the forming of the buffer layer includes forming the buffer layer using epitaxial growth.
3. The method of claim 1 , wherein the forming of the buffer layer includes forming a monocrystalline silicon layer through selective epitaxial growth.
4. The method of claim 1 , further comprising
performing a baking process onto surfaces of the exposed portions of the both sidewalls of the body before the forming of the buffer layer.
5. The method of claim 4 , wherein the performing of the baking process is implemented in a hydrogen atmosphere.
6. The method of claim 1 , wherein the forming of the buried bit line comprises:
forming a cobalt layer;
forming a cobalt silicide by performing annealing; and
removing the cobalt layer.
7. The method of claim 1 , wherein the forming of the protective layer comprises:
forming a first protective layer over an entire surface including the body;
forming a second protective layer having a different etching selectivity from the first protective layer on lower portions of the both sidewalls of the body;
forming a third protective layer having a different etching selectivity from the first protective layer on upper portions of the both sidewalls of the body; and
selectively removing the first protective layer exposed between the second and third protective layers.
8. The method of claim 1 , further comprises:
performing plasma doping on the exposed portions of the both sidewalls of the body to form a first source or drain region before the forming of the buffer layer.
9. A method for fabricating a semiconductor device, comprising:
etching a silicon substrate and forming a plurality of silicon bodies that each have a burial region;
forming a protective layer having open parts that expose both sidewalls of the burial regions of the silicon bodies;
forming a silicon-containing buffer layer that fills the open parts;
forming a metal-containing layer over entire surfaces of the silicon bodies including the silicon-containing buffer layer;
forming a metal silicide layer in the burial regions of the silicon bodies by fully siliciding the silicon-containing buffer layer and the burial regions;
removing the metal-containing layer; and
forming a dielectric layer that gap-fills spaces between the plurality of silicon bodies.
10. The method of claim 9 , wherein the forming of the silicon-containing buffer layer includes forming a monocrystalline silicon layer through selective epitaxial growth.
11. The method of claim 9 , wherein the metal silicide layer comprises a cobalt silicide layer.