High density plasma deposited phosphosilicate glass as pre-metal dielectrics for advanced self-aligned contacts in sub 0.25 μm device technology

High density plasma deposited phosphosilicate glass (PSG) films were evaluated for an application as pre-metal gap-fill dielectric material. A high deposition rate (∼600 nm/min) PSG film with 9 at. % of P and a deposition-to-etch ratio of 5:1 was developed for a void-free gap fill down to 0.04 μm. Chemical-mechanical polish, reactive ion etch, and defect test of the PSG film have revealed that as-deposited PSG has performed similar to the annealed one, and PSG has an excellent film stability. A significant device yield improvement was obtained using this 9 at. % PSG process.