HCl-(NH4)2S2O8体系抛光液中钌的化学机械抛光研究

摘要

金属钌(Ru)有可能作为集成电路中铜互连阻挡层材料,作为阻挡层必须具有低的表面粗糙度.化学机械抛光技术已经成为集成电路制造中实现局部平面化和全局平面化的关键技术,因此对钌的化学机械抛光研究具有重要意义.利用自制抛光液,研究了在HCl-(NH4)2S208体系抛光液中盐(KCl)的浓度、络合剂浓度、pH值和抑制剂(BTA)等对钌的去除速率的影响.实验发现,在HCl-(NH4)2S2O8体系抛光液中,金属钌在1wt.％SiO2、1 wt.％过硫酸铵、1wt.％酒石酸、1 mmol/L BTA和10mmol/L KCl,pH值为9.0的抛光液中,抛光速率为10.8nm/min.电化学实验发现,在lwt.％SiO2、1wt.％过硫酸铵、1wt.％酒石酸、1mmol/L BTA和1mmol/L KCl,pH值为4.0的抛光液中,金属钌表面化学反应受抑制；在1wt.％SiO2、1wt.％过硫酸铵、1wt.％酒石酸、1mmol/L BTA和1 mmol/L KCl,pH值为9.0的抛光液中,金属钌表面钝化膜较致密、较厚.%Ruthenium( Ru) may be used as new barrier materials in copper interconnects of Ultra-Large Sacle Integration(ULSI), and the surface roughness of the barrier layer should be very low. Chemical Mechanical Polish(CMP) technique has become a key technology for Integrated Circuit(IC)device manufacturing to achieve both local and global planarity of wafer surfaces,it is of great importance to study the CMP of Ru. The effect of the concentration of KCl,the concentration of the complex agent,pH value and die inhibitor on the Material Removal Rale( MRR) in HCl-( NH4 )2S2O, slurries was investigated,the results revealed that the MRR attained 10.8 nm/min in the slurry that contained 1 wt. %SiO2,l wt.%(NHJ2S2O,,l wt. % tartaric acid, 1 mmol/L BTA and l0mmol/L KCl,pH value was 9.0. Electrochemical analysis results indicated that the surface reactions were inhibited when pH value was 4.0 and the passivation film was thicker when pH value was 9.0 in the slurries whose composition were 1 wt. % SiO2,1 wt.%(NH4)2S2O8,l wt.% tartaric acid, 1 mmol/L BTA and 1 mmol/L KC1.