Patent ID: 8841198

Claim:
A method for forming an isolation layer of a semiconductor device, comprising the steps of: forming a hard mask on a semiconductor substrate to expose an isolation region; forming a trench by etching the exposed isolation region of the semiconductor substrate; forming a first liner nitride layer on a surface of the trench and the hard mask; forming a flowable insulation layer on the first liner nitride layer to fill the trench; performing a chemical mechanical polishing process to remove a portion of the flowable insulation layer and a portion of the first liner nitride layer until the hard mask is exposed; removing the hard mask; removing a partial thickness of the chemical mechanical polished flowable insulation layer to form a recess in the trench; forming a second liner nitride layer on the partially removed flowable insulation layer, the first liner nitride layer and a surface of the recess; forming an insulation layer on the second liner nitride layer to completely fill the recess; and removing a portion of the insulation layer formed on the semiconductor substrate and over the trench, wherein the steps are carried out sequentially in the order listed above.