Multi-step high density plasma chemical vapor deposition process

Abstract

A method for depositing dielectric material into gaps between wiring lines in the formation of a semiconductor device includes the deposition of three oxide layers using high density plasma chemical vapor deposition (HDPCVD). A first HDPCVD step is carried out while keeping the substrate unbiased to form an oxide layer over the lines and in the gap. A second HDPCVD step in which the substrate is biased deposits a second oxide layer over the first oxide layer. During the second HDPCVD step some etching occurs and a portion of the first oxide layer is removed. A third HDPCVD step is carried out at a greater etch and sputtering rate than the second step to complete filling of the gap with dielectric material. The first oxide layer acts to protect the underlying structures from etching damage during the third step. Gaps between wiring lines can be filled with dielectric material without forming voids, even for high aspect ratio gaps.