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US 6,958,900 B2Granted
Multi-layered unit including electrode and dielectric layer
AssigneeTDK Corporation
InventorYukio Sakashita
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AssigneeTDK Corporation
InventorYukio Sakashita
Estimating the term…
A multi-layered unit according to the present invention includes a support substrate formed of fused quartz, an electrode layer formed on the support substrate and formed of a conductive material, a buffer layer formed on the electrode layer and formed of a dielectric material containing a bismuth layer structured compound having a composition represented by Bi4Ti3O12 and having an excellent orientation characteristic so that the bismuth layer structured compound is oriented in the c axis direction, and a dielectric layer formed on the buffer layer and formed of a dielectric material containing a bismuth layer structured compound having a composition represented by SrBi4Ti4O15 and having an excellent orientation characteristic so that the bismuth layer structured compound is oriented in the c axis direction. Since the thus constituted multi-layered unit includes the dielectric layer containing the bismuth layer structured compound oriented in the c axis direction, in the case of, for example, providing an upper electrode on the dielectric layer to form a thin film capacitor and applying a voltage between the electrode layer and the upper electrode, the direction of the electric field substantially coincides with the c axis of the bismuth layer structured compound contained in the dielectric layer. As a result, since the ferroelectric property of the bismuth layer structured compound contained in the dielectric layer can be suppressed and the paraelectric property thereof can be fully exhibited, it is possible to fabricate a thin film capacitor having a small size, large capacitance and an excellent dielectric characteristic.
A multi-layered unit constituted by forming on a support substrate formed of a material on which crystals cannot be epitaxially grown, an electrode layer formed of a conductive material, a buffer layer containing a bismuth layer structured compound oriented in the [001] direction, and a dielectric layer formed by epitaxially growing a dielectric material containing a bismuth layer structured compound on the buffer layer and oriented in the [001] direction in this order, a bismuth layer structured compound having an orientation characteristic being selected as the bismuth layer structured compound contained in the buffer layer and a bismuth layer structured compound having characteristics as a capacitor material being selected as the bismuth layer structured compound contained in the dielectric layer, thereby forming an interface between the buffer layer and the dielectric layer.
A multi-layered unit comprising:
Dependencies are inferred from the claim text.