Oxidized Ta2O5/Si3N4dielectric films on poly-crystalline Si for dRAMs |
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Authors: | Shinriki H Nishioka Y Ohji Y Mukai K |
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Affiliation: | Hitachi Ltd., Tokyo; |
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Abstract: | A dielectric film technology characterized by a novel multilayer structure formed by oxidation of Ta2O5/Si3 N4 films on polysilicon has been developed to realize high-density dRAMs. The dry oxidation of the Ta2O5/Si3N4 layers was performed at temperatures higher than 900°C. This film has a capacitance per unit area from 5.5 to 6.0 fF/ μm2, which is equivalent to that of a 6.0- to 6.5-nm-thick SiO2. The leakage current at an effective electric field of 5 MV/cm is less than 10-9 A/cm2. Under such an electric field, the extrapolated time to failure for 50% cumulative failure can be as high as 1000 years |
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