Dielectric Engineering on Cell Capacitor for Advanced Trench DRAM
In this paper, we discuss the cell capacitor characteristics via wafer acceptance test (WAT) and reliability test for advanced trench capacitor. Combination of N2O reoxidation and NH3 nitridation processes can improve leakage current and maintain the same level of cell capacitance. This obvious improvement is contributed from extra nitrogen incorporation in reoxidation surface and more oxygen incorporation in nitride layer, which modify the film structure of storage dielectrics. Based on secondary ion mass spectrometer (SIMS) and Fourier transform infrared (FTIR) analysis, we propose the band model to clarify the influence of reoxidation and nitridation processes on cell trench capacitor