Effect of SiO2 Film Deposition on the Ferroelectric Properties of a Pt/Pb(Zr, Ti)O3/Pt Capacitor

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Abstract
The degradation of the ferroelectric properties of a Pt/Pb(Zr, Ti)O3/Pt capacitor due to the back-end process of the ferroelectric random access memory (FRAM) device fabrication process is studied with particular reference to the interlayer dielectric (ILD) and its passivation. The SiO2 film for the ILD layer was deposited by two methods: electron cyclotron resonance chemical vapor deposition (ECR CVD) using SiH4/ N2O gas and atmospheric pressure thermal CVD using tetra ethyl ortho-silicate (TEOS) and O3 ( O3-TEOS CVD). The ECR CVD-SiO2 deposition at temperatures higher than 300° C severely damaged the ferroelectric properties of the Pt/Pb(Zr, Ti)O3/Pt capacitor. However, when the SiO2 film was deposited at temperatures lower than 250° C by ECR CVD, the nonvolatile remnant polarization of a capacitor with an area of 100×100 µ m2 was found to be about 10 µ C/cm2, which makes this a valuable ILD process for FRAM fabrication. The ferroelectric property degradation of the Pt/Pb(Zr, Ti)O3/Pt capacitor by the O3-TEOS SiO2 was less severe than that of the ECR CVD-SiO2. The ferroelectricity of the capacitors damaged by the SiO2 film deposition was recovered by post-annealing.
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