Method for forming contact in semiconductor device

1. A method for forming a contact in a semiconductor device, comprising the steps of:

forming a bit line on a substrate;

forming an oxide layer made of high density plasma (HDP) oxide on a substrate structure including the bit line and the substrate;

forming a hard mask on the oxide layer, wherein the hard mask is made of polysilicon; and

performing an etching process for forming a storage node contact, wherein the etching process is performed after the bit line, the oxide layer and the hard mask are formed with a total stress intensity factor less than a critical value of a lifting phenomenon, the total stress intensity factor being determined by a thickness and a tensile stress of the bit line, the oxide layer and the hard mask layer.

2. The method of claim 1 , wherein the bit line is formed by using tungsten.

3. The method of claim 2 , wherein the bit line has a thickness ranging from approximately 300 Å to approximately 1000 Å.

4. The method of claim 1 , wherein the step of forming the bit line further includes the step of forming a barrier metal layer with the use of Ti and TiN until the barrier metal has a thickness ranging from approximately 100 Å to approximately 1000 Å.

5. The method of claim 1 , wherein the bit line is formed by performing an etching process using an etch gas of, SF 6 , BCL 3 , N 2 , and CL 2 under a pressure ranging from approximately 20 mTorr to approximately 70 mTorr and a power ranging from approximately 300 W to approximately 1000 W.

6. The method of claim 1 , further including the steps of: forming a nitride layer for forming a bit line hard mask on the bit line; and patterning the nitride layer.

7. The method of claim 6 , wherein the nitride layer has a thickness ranging from 2000 Å to approximately 4000 Å.

8. The method of claim 6 , wherein the nitride layer is patterned by using a gas of CF 4 , CHF 3 , O 2 and Ar along with a pressure ranging from approximately 20 mTorr to approximately 70 mTorr and a power ranging from approximately 300 W to approximately 1000 W.

9. The method of claim 1 , wherein the hard mask is formed by performing an etching process using an etch gas of C 2 F 6 , HBr, Cl 2 , Ar and He along with a pressure ranging from approximately 5 mTorr to approximately 20 mTorr and a power ranging from approximately 80 W to approximately 500 W.

10. The method of claim 1 , wherein the etching process for forming the storage node contact proceeds by using an etch gas of C 4 F 8 , C 5 F 8 , C 4 F 6 , CH 2 F 2 , Ar, O 2 , Co and N 2 along with a pressure ranging from approximately 15 mTorr to approximately 50 mTorr and a power ranging from 1000 W to approximately 2000 W.

11. The method of claim 1 , after the step of performing the etching process for forming the storage node contact, further including the steps of:

forming a spacer on lateral sides of a storage node contact hole;

filling a storage node contact plug material into the storage node contact hole; and

performing an etch-back process to the storage node contact plug material to thereby obtain a storage node contact plug.

12. The method of claim 11 , wherein the spacer is made of low pressure nitride.

13. The method of claim 11 , wherein the storage node contact plug material is polysilicon.

14. The method of claim 11 , wherein the storage node contact plug material is formed with a thickness ranging from approximately 1500 Å to approximately 3000 Å.

15. The method of claim 11 , wherein at the step of performing the etch-back process, the hard mask remaining in a cell region and a peripheral region is removed.