Abstract: A variety of techniques may be employed, separately or in combination, to improve the gap-filling performance of a dielectric material formed by chemical vapor deposition (CVD). In one approach, a first dielectric layer is deposited using sub-atmospheric chemical vapor deposition (SACVD), followed by a second dielectric layer deposited by high density plasma chemical vapor deposition (HDP-CVD) or plasma-enhanced chemical vapor deposition (PECVD). In another approach, a SACVD dielectric layer is deposited in the presence of reactive ionic species flowed from a remote plasma chamber into the processing chamber, which performs etching during the deposition process. In still another approach, high aspect trenches may be filled utilizing SACVD in combination with oxide layers deposited at high temperatures.