铜抛光液中缓蚀剂5-氨基四唑(ATA)的作用机制研究

Investigation on the Mechanisms of Corrosion Inhibitor 5-aminotetrazole Used in the Copper Chemical Mechanical Polishing

采用静态腐蚀实验、接触角测试、XPS等手段,比较在不同pH值下抛光液中缓蚀剂(5-氨基四唑(ATA),苯并三唑(BTA))对铜表面化学机械抛光(CMP)的影响,并探讨ATA在铜表面的作用机制。结果表明,BTA和ATA是优良的铜缓蚀剂,当pH值为3～10时,两者可在铜表面成膜,保护铜表面不受腐蚀,从而降低铜片的静态腐蚀速率和去除率,其中当pH=4时,2种缓蚀剂表现出最佳的缓蚀性能。当pH值为3～5时,ATA的缓蚀性能优于BTA。ATA通过四唑环上的N原子和氨基上的N原子吸附在铜表面,形成保护膜,从而抑制了H2O2对铜表面的腐蚀,改善了表面质量,是一种优良的适用于酸性铜抛光液的缓蚀剂。

The influences of inhibitors （ benzotriazole （BTA） and 5-aminotetrazole （ATA） ） in slurry with varying pH values on the chemical mechanical polishing（CMP） of copper were studied by the methods of the static corrosion, contact angle and X-ray photoelectron spectroscopy （XPS） , and the effective mechanisms of ATA on copper surface were discussed. The results show that BTA and ATA are excellent copper corrosion inhibitors. In the range of pH values 3 - 10 ,the inhibitors form the passivity films and protect the copper surface from chemical attack, resulting in the decrease of the removal rates of copper and static corrosion rates,especially in the optimum condition of pH = 4. ATA has better inhibition effect for copper corrosion than BTA in the range of pH = 3 - 5, because ATA molecule can be preferentially adsorbed on copper surface by nitrogen atoms of amidogen and azole to form the protect films, resulting in the inhibition of the oxide formation from hydrogen peroxide and the improvement of the surface quality. In conclusion, ATA is one of the best inhibitors suitable for acid slurry of copper CMP.