| 摘要 |
PURPOSE: A method for fabricating a ferroelectric capacitor is provided to increase remnant polarization and improve reliability related with fatigue, a leakage current and data retention by controlling volatilization and diffusion of bismuth ions. CONSTITUTION: A storage node contact is formed on a substrate. The first adhesion layer/a diffusion barrier layer and a platinum lower electrode(23) are sequentially formed on the resultant structure. A thin film for improving a fatigue characteristic and defending oxygen diffusion is formed on the platinum lower electrode. A SBT(strontium-bismuth-tantalate) thin film of a metastable crystalline phase in which a ferroelectric phase, a pychiore phase and an amorphous phase are mixed is deposited, wherein the SBT thin film is deposited at a low temperature of 150-400 deg.C to control volatilization and diffusion of bismuth ions in the SBT thin film. Bismuth ions are implanted into the SBT thin film of the metastable crystalline phase to supplement diffused or lost bismuth ions. The stacked layers are patterned by a mask and etch process. A high temperature treatment is performed to crystallize the metastable SBT thin film into an SBT ferroelectric thin film of a completed ferroelectric phase. The second adhesion layer/a barrier metal layer are formed on the resultant structure by a mask and etch process and a part of the SBT ferroelectric thin film is exposed. A platinum upper electrode(27) is formed.
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