THE INTEGRATION OF PECVD BPSG FILMS AS A PRE-METAL DIELECTRIC

摘要

Successful integration of plasma enhanced chemical vapor deposited (PECVD) borophosphosilcate (BPSG) films at polysilicon to metal dielectric (PMD) requires that the oxide / BPSG charge (Qox) be controlled. Fixed charges in the underlayer oxide and BPSG films can lower the MOS thick field n-channel VT's by ～20V. The fixed charge levels are influenced by both the deposition (SiO_2 underlayer and BPSG films) and reflow anneal conditions. The deposition conditions used for both the SiO_2 underlayer and BPSG films determine the in-film fixed charges. A correlation has been made between electrical parametric test and surface charge analysis measured inline after deposition and anneal. Fixed charge levels identical to atmospheric pressure (APCVD) processes have been achieved after optimizing the SiO_2 / BPSG depositions and anneal conditions.