Excellent low-pressure-oxidized Si3N4 filmson roughened poly-Si for high-density DRAMs

High-reliability and good-performance stacked storage capacitors with high capacitance value of 17.8 fF/μm² has been realized using low-pressure-oxidized thin nitride films deposited on roughened poly-Si electrodes. These novel electrodes are fabricated by H ₃PO₄-etching and are RCA-cleaned. The leakage current density at +2.5 and -2.5 V are 0.07×10^-9 and -2.4×10^-8 A/cm², respectively, fulfilling the requirements of 256 Mb DRAM's. Weibull plots of time-dependent-dielectric-breakdown (TDDB) characteristics under constant current stress and constant voltage stress also show tight distribution and good electrical properties. Hence, this easy and simple technique is promising for future high-density DRAM's applications