Method of forming semiconductor device including tungsten layer

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

forming a tungsten layer;

sputtering by using a silicon target under atmosphere including nitrogen to form a silicon rich nitride layer over the tungsten layer, thereby the sputtering causing to change a surface of the tungsten layer into a tungsten nitride layer; and

converting the tungsten nitride layer into the tungsten layer.

2. The method of claim 1 , wherein the silicon rich nitride layer has a thickness of 2 to 10 nm.

3. The method of claim 2 , wherein the sputtering is performed by setting a high frequency output at a first power and then setting the high frequency output at a second power higher than the first power.

4. The method of claim 3 , wherein the converting is performed by heating over 600 degrees centigrade.

5. The method of claim 4 , further comprising:

forming a silicon nitride layer over the silicon rich nitride layer by CVD or ALD method.

6. The method of claim 1 , wherein the tungsten layer is formed in a first chamber and sputtering is performed in a second chamber.

7. The method of claim 6 , wherein the tungsten layer is transferred from the first chamber to the second chamber without exposing the tungsten layer over oxygen.

8. The method of claim 3 , wherein the first power is 500 W or less.

9. The method of claim 1 , after the sputtering, the silicon rich nitride layer is exposed over atmosphere including oxygen, thereby the silicon rich nitride layer is converted into a silicon oxynitride layer.

10. The method of claim 9 , wherein the tungsten layer is comprised of a bit line.

11. The method of claim 10 , wherein the tungsten layer is formed over a semiconductor substrate via a silicon nitride layer and a barrier metal layer.