Control And Optimization Of Cu CMP Dishing In GLSI Multilayer Copper Interconnects

With the rapid development of integrated circuits,the feature size of integrated circuit devices continues to decrease,and the wafer size continues to increase.In order to improve the reliability of the device,increase its service life,meet the nano-level accuracy required for photolithography,and ensure the planarization performance of the wafer surface,it must be planarized.Chemical mechanical polishing(CMP)technology is still one of the key processes for achieving local and global planarization during chip preparation,and copper CMP is becoming increasingly important.During the planarization of multi-layer copper interconnects,the extension of dishing seriously affects the follow-up process.It is particularly important to develop the copper slurry to control and optimize the dishing.In this paper,we have innovatively developed a weakly alkaline copper polishing slurry for the control of dishing.Through literature research,the basic components of the slurry were determined as follows: the complexing agent was glycine,and the chelating agent was FA/O,and the oxidizing agent was hydrogen peroxide,respectively each component was subjected to polishing experiments and static corrosion tests.By comparing the control of different inhibitors on dishing,it was determined that benzotriazole was used as an inhibitor and compared to the control of different pH regulators on dishing,tetraethylammonium hydroxide(TEAH)was used as pH adjustment.The control and optimization of dishing by anionic surfactant ammonium dodecyl sulfate(ADS)were studied.When the ADS content was 0.2wt%,the surface tension of the copper polishing slurry was reduced,and the non-uniformity of the wafer surface after polishing was 4.15%,and the surface roughness was reduced to 3.02 nm.The dishing was controlled at 689 ?.Through the optimization of copper slurry,the pH value of slurry was finally determined to be 8.8,the removal rate of copper was 2438 ?/min,and the 65 nm wafers of 3-inch was verified to be controlled at 610 ? which meets the industry's demand for dishing which needs less than 800 ?.For different sizes of copper wiring,multi-size copper pattern wafer of 8-inch was used to test the graphics,and polishing was performed using a weakly alkaline copper slurry.The test results show that the finer the lines,the better the control effect of dishing,and the control of dishing in the center of the wafer is significantly better than that of dishing in the edge region.The research content provides a theoretical basis for the control of copper CMP dishing in multi-layer copper interconnect and the study of the copper slurry.