On-Wafer Test Method of Metal-Insulator-Metal Capacitor Life using Time Dependent Dielectric Breakdown

Abstract

We have developed a novel test method for on-wafer measurement of median time to failure (MTTF) of MIMCAP dielectric under an applied electric field using the concept of Time Dependent Dielectric Breakdown (TDDB). This method requires a small number of samples on wafer, and the tests are relatively quick. The feedback on dielectric quality to production team occurs much sooner than what is possible using conventional TDDB test method. We have also measured MTTF of MIMCAP dielectric using an alternate method called the Ramp Voltage Test, and compared the results with MTTF data from the TDDB method. The results from these two methods were in good agreement. This has enabled us to employ the on-wafer TDDB test method to assess the MIMCAP nitride quality in production and engineering environment.