Base On Deep Submicron Integrated Circuit,Study On The Structure And Performance Improvement Of MIM Capacitor

As a main passive device,capacitance has been used more and more in IC design.However,MIM(Metal Insulator Metal)capacitance is widely used in the 0.11?m/0.18?m line width process by virtue of its low parasitic capacitance and low contact resistance.MIM capacitors use metal as upper and lower plates,and copper and aluminum are respectively used as electrodes in the process of 0.11?m and 0.18?m wire width.Capacitor media are usually produced by Silicon Nitride and Silicon Oxide.The two capacitive media membranes are usually prepared by the process of PECVD(Plasma Enhance Chemical Vapor Deposition).Silicon oxide as insulation film is commonly used in the early development of 0.18?m line width of aluminum metal interconnect technology,it was adopted and has been applied in actual production,but in the density of the capacitor from 1fF/?m~2 to 2fF/?m~2 in the process of development,in the silicon oxide as the capacitor dielectric film thickness thinning will grow because time is too short and RF power performance is not stable can't achieve the regular production.In this paper,the development of 2fF/?m~2 capacitance density in 0.18?m process was studied through analysis and comparison,and the solution was proposed.According to the theory of capacitance formula,d under the condition of no reduction in thickness,try applying higher dielectric constant of silicon nitride to replace silicon dioxide as 0.18?m technology of MIM capacitor dielectric film,and spread by the silicon nitride design verification test,and get better by optimizing the gas mixture ratio of silicon nitride thin film,finally achieve 0.18?m process 2fF/?m~2 MIM capacitance stability of production.In the process of 0.11?m copper process with smaller line width,the MIM capacitor material is usually made of silicon nitride.However,as the application of capacitance structure in circuit design becomes more and more complex,the breakdown problem of feedback MIM capacitance is often encountered in practical application.In this paper,the possible causes of MIM capacitance failure are analyzed and studied.By designing the corresponding silicon nitride deposition and copper metal crystal dome experiment,the causes leading to MIM capacitance failure are found.Through in-depth study on MIM capacitance reliability using silicon nitride as dielectric film,it is found that the stress problem of silicon nitride as capacitor medium directly affects the quality of silicon nitride and the performance of capacitance.According to the stress of silicon nitride problem,RI by refractive index with silicon nitride dielectric constant and thermal stress,the relationship between find we want the dielectric constant and the stress is on the contrary,in this case,the study design a new silicon nitride deposition program Low RI+High RI+Low RI sandwich structure,through the analysis of the fishbone diagram film-forming process factors of the impact of RI,then design experiment,optimizing the MIM capacitor dielectric film,and through the reliability test,the MIM capacitor life time TTF of the new silicon nitride program deposition is significantly improved compared with the old silicon nitride.In the application of the product,the yield is comparable with baseline and stable,achieving very ideal results.