Method of forming shallow trench isolation in a semiconductor device

1 . A method of forming a shallow trench isolation (STI) layer in a semiconductor device, comprising:

depositing a silicon nitride layer as a hard mask layer on a silicon substrate;

forming a first moat pattern in the silicon nitride layer by a photolithography process;

patterning the silicon nitride layer by a dry etching process using the first moat pattern as an etching mask;

forming a shallow trench by dry-etching the substrate that is exposed by the patterned silicon nitride layer;

removing the first moat pattern after forming the shallow trench;

removing the patterned silicon nitride layer;

filling the shallow trench with a gap-fill insulation layer;

forming a second moat pattern;

removing the gap-fill insulation layer by dry etching process using the second moat pattern as an etching mask; and

removing the second moat pattern so as to form a shallow trench isolation layer.

2 . The method of claim 1 , wherein a depth of the shallow trench is 3000-5000 Å.

3 . The method of claim 1 , wherein a width of the shallow trench is 1500-3000 Å.

4 . The method of claim 1 , further comprising, after filling the shallow trench with a gap-fill insulation layer, planarizing the gap-fill insulation layer by polishing.

5 . The method of claim 4 , wherein, in the planarizing of the gap-fill insulation layer, an etch-stop point is obtained by repeating time-planarizing and monitoring.

6 . The method of claim 4 , wherein the forming a second moat pattern comprises:

coating a photoresist on the planarized gap-fill insulation layer; and

forming a photoresist pattern by exposing and developing the photoresist using a photomask.

7 . The method of claim 1 , wherein, in the patterning the silicon nitride layer by a dry etching process, an etching apparatus using a magnetically enhanced reactive ion etching (MERIE) method is used.

8 . The method of claim 7 , wherein, in the patterning the silicon nitride layer by a dry etching process: an etching gas of CHF3 is flowed at 40-80 sccm, O2 is flowed at 0-20 sccm, and Ar is flowed at 6-120 sccm; a pressure of an etching chamber is maintained at 20 mTorr-70 mTorr; and an RF power is maintained at 200 W-300 W.