Study On The Planarization Process And Material Of GLSI Aluminum Gate

With the continuous improvement of integrated circuit?IC?technology and continuous decrease of device feature size,in order to meet IC highly integrated,high-performance,high speed and low power consumption,Fin field-effect transistor?FinFET?has been the core of advanced CMOS technology,which structure changes from SiON/poly silicon gate to high dielectric material/metal gate.Because aluminum has higher conductivity and better compatibility with high K dielectric material,it is widely used far gate material.During the preparation process of aluminum gate devices,HKMG Aluminum gate CMP is the key technology.The integrity and reliability of device is influenced directly by the effect of aluminum gate planarization.The important goal of aluminum gate CMP is to gain high selective removal of materials and good surface quality,and the slurry is the key factor to influence the effect of aluminum gate planarization.Aiming at the removal rate selectivity of gate aluminum and barrier layer cobalt in the aluminum gate CMP,oxidation-passivation and selective chelation were used in this study,high selective removal of material was achieved and the removal selectivity mechanism of cobalt and aluminum was revealed.It was found that when added oxidant H₂O₂ in the slurry,the removal rate ratio of cobalt and aluminum can be controlled effectively by using selective chelation acting of chelating agent and the control area was from 0.91 to2.12.When the concentration of FA/O?chelating agent was 0.25 ml/L,the removal rate ratio of cobalt and aluminum was 1:1.When adding 15 ml/L FA/O?nonionic surfactant in such alkaline slurry,the surface roughness of cobalt and aluminum wafer was the smallest,which were 5.46 nm and 4.10 nm respectively.By adjusting polishing process and slurry reagents,the effective control on removal rate and polishing effect of cobalt and aluminum can be achieved.Aluminum is a lively amphoteric metal.Hydrogen evolution reaction happens when the pH of the alkaline slurry is above 8.3,and the hydrogen bubbles generate on the surface of the aluminum gate,which lead to many corrosion pit defects.It was obtained that,adding 15 ml/L FA/O?nonionic surfactant into the slurry,the contact angle of the slurry was the smallest,the aluminum wafer has the fewest corrosion pit defects,and the restraint effect of hydrogen evolution corrosion is the best,by contact angle tests and static corrosion experiments.The change trend of aluminum removal rate,pH value,particle size,viscosity and specific gravity of aluminum gate CMP alkaline slurries with the changing of storage time under the condition of different pH values were studied.It was found when the initial pH value of alkaline slurry was 10.00,the aggregate balance of aluminum removal rate,polishing effect and slurry stability was realized.Using the alkaline slurry of 48 hours stable storage,the aluminum removal rate was 139 nm/min and the roughness was 13.3 nm,which can meet the removal rate requirement of aluminum film in aluminum gate CMP and also has great guiding significance on the early realization of industrialization of domestic alkaline slurry of aluminum gate CMP.