Semiconductor devices and methods of manufacturing the same

1. A method of manufacturing a semiconductor device, comprising:

forming contact plugs, each having a top surface having a lower height than a top surface of an etch stop layer, in respective contact holes formed to penetrate a first interlayer insulating layer and the etch stop layer formed on the first interlayer insulating layer;

forming a second interlayer insulating layer disposed on the etch stop layer and within the contact holes;

forming line trenches through which the respective contact plugs are exposed by etching the second interlayer insulating layer; and

forming lines, coupled to the contact plugs, in the respective line trenches.

2. The method of claim 1 , wherein forming the contact plugs comprises:

forming the contact plugs, each having the top surface having a height equal to the top surface of the etch stop layer; and

etching the contact plugs so that the top surface of the contact plugs is lower than the top surface of the etch stop layer.

3. The method of claim 1 , wherein forming the contact plugs comprises:

forming the contact plugs, each having the top surface having a height equal to a top surface of the first interlayer insulating layer; and

etching the contact plugs so that the top surface of the contact plugs is lower than the top surface of the first interlayer insulating layer.

4. The method of claim 1 , wherein forming the trenches comprises etching the second interlayer insulating layer where the etch stop layer and the second interlayer insulating layer have a relatively high degree of etch selectivity.

5. The method of claim 1 , wherein forming the lines comprises:

forming a barrier layer so that regions corresponding to openings of the etch stop layer, from the trenches, and regions where the contact plugs are not formed, from the contact holes, are fully filled with the barrier layer; and

forming a metal layer on the barrier layer so that the trenches are fully filled.

6. The method of claim 1 , wherein a difference A between the height of the top surface of the contact plugs and the height of the top surface of the etch stop layer is determined on the condition that a distance D between the contact plug and the lines adjacent to each other is a critical distance k or higher, wherein the critical distance k is a distance that does not generate a leakage current between the contact plug and the lines adjacent to each other.

7. The method of claim 1 , wherein the difference A between the height of the top surface of the contact plugs and the height of the top surface of the etch stop layer is determined to satisfy the equation:

D 2 =A 2 +( L−O ) 2

wherein D>k, L is a distance between the contact plugs adjacent to each other, and O is a misalignment value between the line and the contact plug.

8. The method of claim 1 , further comprising:

forming a gap region between the lines adjacent to each other by etching the second interlayer insulating layer, after forming the lines; and

forming an air gap between the adjacent lines by forming an insulating layer on the gap regions.

9. A method of manufacturing a semiconductor device, comprising:

forming an etch stop layer on a first interlayer insulating layer;

forming contact holes passing through the etch stop layer and the first interlayer insulating layer;

forming contact plugs having a height lower than the top surface of the etch stop layer, in the respective contact holes;

forming a second interlayer insulating layer on the etch stop layer and within the contact holes;

forming line trenches passing through the second interlayer insulating layer and exposing a portion of the contact plugs and the etch stop layer; and

forming lines coupled to the contact plugs, in the respective line trenches.

10. The method of claim 9 , wherein the second interlayer insulating layer is interposed between the lines and the etch stop layer within the contact holes.

11. A method of manufacturing a semiconductor device, comprising:

forming a first interlayer insulating layer including contact plugs passing through the first interlayer insulating layer;

forming an etch stop layer on the first interlayer insulating layer including openings passing through the etch stop layer and exposing the contact plugs;

forming a second interlayer insulating layer on the etch stop layer and within the openings;

forming line trenches passing through the second interlayer insulating layer and exposing a portion of the contact plugs and the etch stop layer; and

forming lines coupled to the contact plugs, in the respective line trenches.

12. The method of claim 11 , wherein top surfaces of the contact plugs are lower than a top surface of the first interlayer insulating layer.

13. The method of claim 11 , wherein the second interlayer insulating layer is interposed between the lines and the etch stop layer within the openings.