Semiconductor device with filling layer and method for fabricating the same

1 . A method for fabricating a semiconductor device, comprising:

providing a bottom conductive layer;

forming a conductive structure, comprising:

forming a conductive concave layer on the bottom conductive layer and comprising a top surface and a recess having a V-shaped cross-sectional profile recessed from the top surface, wherein the top surface of the conductive concave layer has a first portion formed around the recess; and

forming a conductive filling layer on the conductive concave layer to cover the first portion of the top surface of the conductive concave and to fill into the recess; and

forming a top conductive layer on the conductive structure;

wherein the conductive filling layer comprises germanium or silicon germanium.

2 . The method for fabricating the semiconductor device of claim 1 , wherein the conductive concave layer comprises polycrystalline silicon and/or polycrystalline germanium with substantially no oxygen and nitrogen.

3 . The method for fabricating the semiconductor device of claim 2 , further comprising forming a first dielectric layer on the bottom conductive layer, wherein the conductive structure is positioned in the first dielectric layer at a position that the top surface of the conductive concave layer is positioned below a top surface of the first dielectric layer.

4 . The method for fabricating the semiconductor device of claim 3 , further comprising forming a barrier layer positioned between the conductive structure and the top conductive layer, wherein the barrier layer and the conductive concave layer are separated by the conductive filling layer, such that the barrier layer does not contact with the top surface of the conductive concave layer.

5 . The method for fabricating the semiconductor device of claim 4 , wherein the first dielectric layer comprises a dielectric material comprising oxygen atoms and/or nitrogen atoms.

6 . The method for fabricating the semiconductor device of claim 5 , wherein the barrier layer comprises titanium, titanium nitride, tantalum, tantalum nitride, or a combination thereof.

7 . The method for fabricating the semiconductor device of claim 6 , wherein the top conductive layer comprises aluminum, tungsten, copper, or a combination thereof.

8 . The method for fabricating the semiconductor device of claim 7 , wherein a width of the conductive concave layer and a width of the conductive filling layer are substantially the same.

9 . The method for fabricating the semiconductor device of claim 8 , wherein a top surface of the conductive filling layer and the top surface of the first dielectric layer are substantially coplanar.

10 . A method for fabricating a semiconductor device, comprising:

providing a substrate;

forming a first dielectric layer on the substrate;

forming a first opening along the first dielectric layer;

forming a conductive concave layer in the first opening, wherein a top surface of the conductive concave layer is formed below a top surface of the first dielectric layer;

forming a conductive filling layer on the conductive concave layer within the first opening to cover the top surface of the conductive concave layer; and

forming a top conductive layer on the conductive filling layer;

wherein the top surface of the conductive concave layer has a recess recessed from the top surface of the conductive concave layer to have a V-shaped cross-sectional profile, and a first portion formed around the recess;

wherein the conductive concave layer and the conductive filling layer together configure a conductive structure;

wherein the conductive filling layer comprises germanium or silicon germanium.

11 . The method for fabricating the semiconductor device of claim 10 , wherein the conductive concave layer comprises silicon and/or germanium with substantially no oxygen and nitrogen.

12 . The method for fabricating the semiconductor device of claim 11 , further comprising forming a barrier layer between the top conductive layer and the conductive filling layer, wherein the barrier layer and the conductive concave layer are separated by the conductive filling layer, such that the barrier layer does not contact with the top surface of the conductive concave layer.

13 . The method for fabricating the semiconductor device of claim 12 , wherein the barrier layer comprises titanium, titanium nitride, tantalum, tantalum nitride, or a combination thereof.

14 . The method for fabricating the semiconductor device of claim 13 , wherein the top conductive layer comprises aluminum, tungsten, copper, or a combination thereof.