Method for fabricating semiconductor device and wire with silicide

1. A method for fabricating semiconductor devices, comprising:

forming a trench semiconductor device on a substrate, wherein the trench semiconductor device comprises a source line connecting to a source region disposed on the bottom of the trench, and a top surface of the source line is higher than a surface of the substrate;

forming a first dielectric layer on the trench semiconductor device;

forming a conductive layer on the first dielectric layer;

forming a patterned hard mask layer on the conductive layer;

using a hard mask layer as a mask, and removing a portion of the conductive layer and a portion of the first dielectric layer in sequence;

forming a spacer on the sidewalls of the first dielectric layer, the conductive layer and the patterned hard mask layer;

removing the patterned hard mask layer; and

forming a silicide on the conductive layer.

2. The method for fabricating semiconductor devices as claimed in claim 1 , wherein the step for forming the trench semiconductor device comprises:

forming a trench on the substrate;

forming a second dielectric layer, a second conductive layer and a third dielectric layer on the sidewalls of the trench in sequence, wherein the trench keeps an opening which exposes a portion of the substrate; and

forming a source wire in the opening.

3. The method for fabricating semiconductor devices as claimed in claim 1 , further comprising performing a pre-sputtering process on conductive layer before the silicide is formed on the conductive layer.

4. The method for fabricating semiconductor devices as claimed in claim 1 , further comprising forming a source region and a drain region in the substrate on two sides of the spacer respectively after the spacer is formed on the sidewalls of the first dielectric, the conductive layer and the patterned hard mask layer, and before the patterned hard mask layer is removed.

5. The method for fabricating semiconductor devices as claimed in claim 4 , further comprising forming the silicide on the source region and the drain region.

6. The method for fabricating semiconductor devices as claimed in claim 1 , wherein the step of the patterned hard mask comprises:

forming a hard mask layer on the conductive layer;

forming a patterned photoresist layer on the hard mask layer;

using the patterned photoresist layer as a mask, and removing a portion of the hard mask layer; and

removing the patterned photoresist layer.

7. The method for fabricating semiconductor devices as claimed in claim 1 , wherein the step for forming the spacer on the sidewalls of the conductive layer and hard mask layer comprises:

forming a conformal insulation layer on the substrate; and

performing a non-isotropic etching process on the insulation layer.

8. The method for fabricating semiconductor devices as claimed in claim 1 , wherein the step for forming the silicide comprises:

forming a conformal metal layer on the substrate;

performing a thermal process on the metal layer to cause the metal layer to react with the conductive layer to generate a silicide layer; and

removing the metal layer that has not reacted.

9. The method for fabricating semiconductor devices as claimed in claim 1 , wherein the material of the patterned hard mask layer comprises silicon oxide.

10. The method for fabricating semiconductor devices as claimed in claim 1 , wherein the material of the spacer comprises silicon nitride.

11. The method for fabricating semiconductor devices as claimed in claim 1 , wherein the material of the silicide comprises cobalt silicate or tungsten silicate.