The study of Shallow Trench Isolation gap-fill for 28nm node and beyond

In this paper, a conception of Dep-Etch-Dep was proposed to extend the gap-fill capability of High Aspect Ratio Process (HARP) for Shallow Trench Isolation (STI) at 28nm node. Silicon oxide liner deposited by Atom Layer Deposition (ALD), which has no loading effect, can enlarge the process window. After the deposition of silicon oxide liner, an available multi-cycles SiCoNi dry etch process was applied to trim off the silicon oxide near the entrance, and got prefect V shape recess structure. Then, the STI was filled up with silicon oxide by HARP, and the seam was repaired during steam anneal. The TEM images showed good gap-fill performance using ALD-SiCoNi-HARP (ASH) approach.