Effect of Various Complexing Agents for Cobalt “bulk step” Chemical Mechanical Planarization

In this paper, various complexing agents were evaluated for cobalt chemical mechanical planarization(CMP) in H
₂
O
₂
based slurry, during “bulk step” process. Firstly, effect of different complexing agents on polishing removal rate(RR) and dissolution rate (DR) of Co were studied. The results showed that glycine has the highest Co RR compared with other complexing agents, such as citric acid(CA), tartaric acid(TA), potassium citrate(PC), potassium tartrate(PT). Comparison of corrosion current of different complexing agents was observed by electrochemical measurement. However, the glycine has a has higher Co DR without inhibitor. Thus, Carboxyl benzotriazole (CBT) was used as inhibitor in glycine-H
₂
O
₂
, based slurry. The results showed that CBT can effectively reduce the Co DR and passivate the Co surface, achieve a good surface quality and maintain a desirable Co RR with a few amount of CBT added into the slurry.