ATMP在钴互连集成电路钴膜CMP中的作用机理研究

Study on the mechanism of ATMP in cobalt film CMP of cobalt interconnect integrated circuit

为了提高钴互连集成电路钴膜化学机械平坦化(CMP)中钴的去除速率以及Co/TiN去除速率选择性,研究了氨基三甲叉膦酸(ATMP)作为络合剂,在钴互连集成电路钴膜CMP中的作用机理。通过CMP、电化学、X射线电子光谱等实验探究了ATMP的络合性能,采用X射线电子光谱以及密度泛函理论的建模仿真对ATMP在抛光液中的络合机理进行了深入分析。实验结果表明:ATMP的添加不同程度地加快了钴和氮化钛腐蚀,可以有效地提高钴互连集成电路钴膜CMP的去除速率以及Co/TiN去除速率选择性;X射线电子光谱实验显示ATMP的络合作用可以降低钴表面氧化层的厚度;根据密度泛函理论计算结果可以发现,ATMP中的磷酸基团为活性位点,与晶圆表面金属离子形成络合物,从而实现快速去除。可见ATMP可以作为络合剂应用于钴布线钴膜CMP制程。

To improve the cobalt removal rates and the selectivity of Co/TiN removal rates, amino trimethylene phosphonic acid(ATMP) was used as the complexing agent for chemical mechanical flattening(CMP) of cobalt films in interconnect applications. The complexation properties of the ATMP were investigated by polishing, electrochemistry and XPS experiments. The complexation mechanism of the ATMP to Co ions was analyzed by XPS experiments and density functional theory simulation. Experiments of polishing and electrochemistry prove that the addition of ATMP accelerates the corrosion of metal and improves cobalt removal rates and selectivity of Co/TiN removal rates. XPS experiments show that the complexation of the ATMP can reduce the thickness of the oxide layer on the cobalt surface. The density functional theory calculation results show that the phosphate group in ATMP is the reactive site, which is easy to form complex with metal ions on the wafer surface to increase removal rates. The above results show that ATMP can be used as an effective complexing agent in cobalt film polishing.