Copper Interconnect Plating Process Research And Equipment Improvements

With decreasing feature sizes of semiconductor devices, copper interconnect process of electroplating process of coating thickness uniformity requirements are also increasing, traditional vertical and horizontal plating equipment does not apply to growing ultra-large-scale integrated circuit copper interconnect plating process. Improvement on the original plating equipment becomes an effective way to solve the uneven coating thickness.Electroplating copper interconnects major uniformity in coating thickness phenomena were studied, and several important parameters affecting the quality of the coating was studied. With the physical vapor deposition PVD-300bulid by institute of Microelectronics of China Academy of Sciences sputtering44.8nm of copper crystal layer, the square resistance tests carried out, the results show good uniformity. Then copper seed layer is washed, soaked60s in the activator to the oil, and then rinsed in DI water for20s, finally soaked in dilute sulfuric acid solution for120s, and then cleaned with DI water and stir3times, each cleaning time is20s, with high purity N2, which can effectively remove surface oil and seed layer of copper oxides. During the electroplating plating, select a special copper interconnect solution:Xin Yang electroplating solution SYS2330, and with special additives UPT3210A UPT3210L, the ratio of each one liter SYS2330need to add5mlUPT3210A and5m13210L, another addition of2-Tetrahydrothiazolyl Thione(H1)1.0mg/L, phenyl C6H12O6S4Na2(S1)10mg/L to reduce coating internal stress. Cathode current density2.42A/dm2. Temperature is20℃, for horizontal and vertical plating. Square resistance test for the completion of the plating, the test results show that non-uniform thickness still exists. The case of this nonuniformity was analyzed, the uneven thickness distribution is non-uniform current density distribution on wafer caused.Aiming uneven coating thickness above, combined with institute of Microelectronics of China Academy of Sciences research conditions, from equipment gives arched copper anode, clubbed copper anode, removable aqueduct, double anode system improvement program, combined these four programs form the final solution of phosphor copper ball double anode system.