| 摘要 |
PURPOSE: A fabrication method of ferroelectric memory devices is provided to improve a characteristic of a ferroelectric capacitor by keeping a regular residual polarization on a ferroelectric thin film for a comparatively long time. CONSTITUTION: Contact holes are formed by selectively etching the interlayer dielectrics(34,36) formed on a substrate(30). Polysilicon plugs(37) are formed and connected to the substrate(30) through the contact holes. A titanium layer(38), a titanium nitride(39), a platinum layer(40) for forming lower electrodes and a thin film(41) made of PbBi2Ta2O9 are sequentially formed on the entire surface of the resultant structure. Then, the thin film(41), the platinum layer(40), the titanium nitride(39) and the titanium layer(38) are sequentially and partially etched to form a pattern. A protection layer(42) made of SrBi2-xTa2O9-x formed by annealing at the temperature of 500-700 deg.C is formed on the resultant structure to prevent diffusion of hydrogen ions to the thin film(41), thereby keeping a regular residual polarization on the thin film(41) for a comparatively long time. A protection oxide(43) is formed on the protection layer(42). The protection oxide(43) and the protection layer(42) are partially etched to expose the thin film(41). Upper electrodes are formed by the steps of depositing and etching a platinum layer(44).
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