Method for forming pattern in semiconductor device

1. A method for forming an etch pattern in a semiconductor device, comprising:

forming a hard mask layer comprising a tungsten layer and an amorphous carbon layer on an etch target layer;

selectively etching the amorphous carbon layer using a gas mixture including N 2 and H 2 or N 2 and Cl 2 to form an amorphous carbon pattern; and

etching the tungsten layer by using the amorphous carbon pattern to form a hard mask pattern for forming the etch pattern.

2. The method of claim 1 , further comprising:

etching the etch target layer by using the hard mask pattern as an etch barrier.

3. The method of claim 1 , wherein selectively etching the amorphous carbon layer, includes:

etching the amorphous carbon layer until a remaining amorphous carbon layer portion has a certain thickness; and

etching the remaining amorphous carbon layer portion using the gas mixture including N 2 and H 2 or N 2 and Cl 2 .

4. The method of claim 1 , wherein the etch target layer includes a conductive layer.

5. The method of claim 3 , wherein the etching the amorphous carbon layer until a remaining amorphous carbon layer portion has a certain thickness, comprises using a gas mixture having a fast etching rate of the amorphous carbon and providing a sufficient etching margin.

6. The method of claim 3 , wherein the remaining amorphous carbon layer portion has a thickness of approximately 200 Å to approximately 500 Å.

7. The method of claim 3 , wherein etching the remaining amorphous carbon layer portion comprises using a gas mixture providing resultants not reacting with the tungsten layer.

8. The method of claim 3 , wherein after etching the remaining amorphous carbon layer portion, etching the tungsten layer comprises removing a portion of the exposed tungsten layer with an additional treatment by a mixture of plasma.

9. The method of claim 4 , wherein the etch pattern includes a bit-line.

10. The method of claim 5 , wherein the gas mixture used for etching the amorphous carbon layer comprises N 2 and O 2 gases.

11. The method of claim 8 , wherein the mixture of plasma includes CF 4 and Ar.

12. The method of claim 8 , wherein the removed portion of the exposed tungsten layer portion has a thickness of approximately 20 Å to approximately 100 Å.

13. The method of claim 8 , wherein etching the amorphous carbon layer, etching the remaining amorphous carbon layer portion, and removing a portion of the exposed tungsten layer are performed in situ.

14. A method for forming an etch pattern in a semiconductor device, comprising:

forming a hard mask layer comprising a tungsten layer and an amorphous carbon layer on a etch target layer;

selectively etching the amorphous carbon layer until a remaining amorphous carbon layer portion has a certain thickness;

etching the remaining amorphous carbon layer portion until a corresponding tungsten layer portion is exposed to form an amorphous carbon pattern;

etching the tungsten layer comprises removing a portion of the exposed tungsten layer;

etching a remaining tungsten layer portion by using the amorphous carbon pattern as an etch mask to form a tungsten pattern; and

etching the etch target layer by using the tungsten pattern as an etch mask to form an etch pattern.

15. The method of claim 14 , wherein etching the amorphous carbon layer comprises using a gas mixture including N 2 and O 2 gases.

16. The method of claim 14 , wherein etching the remaining amorphous carbon layer portion comprises using a gas mixture including N 2 and H 2 or N 2 and Cl 2 .

17. The method of claim 14 , wherein etching the tungsten layer comprise using a gas mixture of plasma including CF 4 and Ar.