Study of high density plasma etch for borderless contact to solve bottom anti-reflective coating defect for beyond 0.18 μm VLSI technology

The strip-like defect occurred for contact etch process with inorganic BARC-SiON on high density plasma etch chamber TCP9100 was studied. The interaction of SiON and photo resist on TCP9100 high density plasma was assumed and been identified in this work. A new contact scheme by inserting PEOX film between photo resist and SiON, and rearrange contact etch sequence to process bottom liner etch after in-situ photo resist step were proposed to solve this strip-like defect. The L9 experiment were also been done to get a new etch recipe to compensate CD bias shift due to new approach for defect reduction, which include BARC open step time, ILD oxide main etch step time and ILD oxide over etch gas chemistry. The results showed new approach can effectively eliminated defect occurred, and both contact resistance and CP yield can be improved from this change