Abstract: The present invention provides a multi-steps depositing process. The process provides a substrate having at least a shallow trench, and then performs a first high density plasma chemical vapor deposition (HDP CVD) to form a first dielectric layer on the substrate and a surface of the shallow trench. A partial etching process is performed to etch the first dielectric layer, and a passivation process is performed. Finally, a second HDP CVD is performed to form a second dielectric layer on the first dielectric layer and fill the shallow trench.