Study On The Planarization Efficicency Of Alkaline Copper Slurry In GLSI Multilevel Copper Interconnection

With the feature size of integrated circuit shrinking constantly, the width of metal interconnects decreasing continually and the layers of wiring increasing quickly, the RC delay and power loss are to be important factors to restrict the integration level of semiconductor devices gradually. The traditional aluminum wiring has been gradually replaced by copper interconnect structure, because of its high resistivity and weak of electro-migration resistance. As the porous low-k dielectric materials introduce in copper interconnect structure, it can reduce the device RC delay to an acceptable range effectively. Meanwhile, copper is difficult to be etched in wiring process, was successfully solved by the dual damascene, which can contribute to the feature size of integrated circuit keep shrinking further. As the integrated circuit feature size shrinking to 65 nm, three steps of planarizaiton(bulk copper eliminated, residual copper eliminated and barrier layer eliminated) are necessarily required to achieve the wafer global planarizaiton for meeting the lithography nanometer precision. Currently, Chemical Mechanical Planarization(CMP) is recognized as the only way to get to global planarization.In this paper, a kind of novel alkaline copper slurry used in bulk eliminated process was studied for meeting the planarization requirement in copper interconnection structure. It solved effectively the difficulties of copper oxidation and hydroxide indissolvable in alkaline environment through using hydroxy amine which independent researched by the Institute of Microelectronics of Hebei University of Technology. Avoiding to using corrosion inhibitors(BTA) by virtue of the self-passivation action of oxidant, the heave position quickly reaction and the recess position realize self-passivation, which is in favor of obtaining good planarization result with a rapid removal rate. Compared with the traditional acid slurry, it contains four kinds of chemical reagent, low cost, non-corroding equipment, and no addition of benzotriazole(BTA), environmentally friendly. The variation tendency of copper removal rate and step height caused by changing the components of slurry and process conditions were acquired through a series single-factor experiments and planarization experiments which carried on pattern wafers, respectively. Based on the previous researches, we optimized the slurry components, and certified finally the optimum proportion in terms of the synergistic effect of the components under the process conditions: applied pressure 1.5psi(1psi=6.895Kpa), polish head/polish plate 97/103 rpm, flow rate 300ml/min. The concentration of colloidal silica, FA/O V chelating agent, FA/O I nonionic surfactant and oxidizing agent(H2O2) were identified as 8.8wt%, 2Vol%, 1Vol% and 3Vol%, respectively.The experimental results performed on 12 inch blanket wafer(M1) indicate that the copper removal rate can achieve to 6512.5?/min, and the within wafer non-uniformity(WIWNU) is only 3.32% less than the industrialization indexes(5%) under the above-mentioned process conditions. After polishing 69 s, the residual step height of pattern wafer is below 400?, means that this kind of novel alkaline copper slurry owns rapid removal rate selectivity between the heave and recess position, and also indicates that this kind of slurry can achieve global planarization with a rapid removal rate. On 12 inch wafer(M8), the copper removal rate can achieve to 7197.6?/min, and eliminated 10462? after polishing 85 s.