Time-dependent dielectric breakdown evaluation of deep trench capacitor with sidewall hemispherical, polysilicon grains for gigabit DRAM technology

The continued scaling of DRAM cell sizes requires maintaining a sufficiently high storage capacitance per cell. Capacitance enhancement technique using hemisphericalpolysilicon grains (HPG) in deep trench capacitors has been previously reported for the continued scaling of deep trench DRAM technology [l]. In this paper, the reliability aspects of such HPG deep trench capacitors are critically investigated. The operational lifetime, based on constant voltage stressing, demonstrates the feasibility of such capacitors for gigabit DRAM applications.