Coating solutions for use in forming bismuth-based ferroelectric thin films, and ferroelectric memories formed with said coating solutions, as well as processes for production thereof

A ferroelectric thin film formed by:

• applying a coating solution containing metal alkoxides of Bi, metallic element A, wherein A is at least one metallic element selected from the group consisting of Bi, Pb, Ba, Sr, Ca, Na, K and rare earth elements, and metallic element B, wherein B is at least one metallic element selected from the group consisting of Ti, Nb, Ta, W, Mo, Fe, Co and Cr, and composite metal alkoxides formed by any two or more of said metal alkoxides,
• onto an electrode on a substrate, and then
• annealing the applied coating,
• wherein said electrode is made of at least one metal selected from the group consisting of Ir, Ru, Rh, Re and Os and/or at least one metal oxide thereof.

A ferroelectric thin film formed by:

• applying a coating solution containing metal alkoxides of Bi, metallic element A, wherein A is at least one metallic element selected from the group consisting of Bi, Pb, Ba, Sr, Ca, Na, K and rare earth elements, and metallic element B, wherein B is at least one metallic element selected from the group consisting of Ti, Nb, Ta, W, Mo, Fe, Co and Cr, and composite metal alkoxides formed by any two or more of said metal alkoxides,
• onto an electrode on a substrate,
• exposing the applied coating to a humidified atmosphere, and then
• annealing said coating,
• wherein said electrode is made of at least one metal selected from the group consisting of Ir, Ru, Rh, Re and Os and/or at least one metal oxide thereof.

The process for producing a ferroelectric thin film by the steps of:

• (I) forming an electrode over a substrate;
• (II) applying a coating solution for use in forming a ferroelectric thin film onto said electrode;
• and
• (III) annealing the applied coating;
• wherein said process uses, as said coating solution for use in forming ferroelectric thin films, a Bi-based coating solution for use in forming ferroelectric thin films, containing Bi, metallic element A (which is at least one metallic element selected from the group consisting of Bi, Pb, Ba, Sr, Ca, Na, K and rare earth elements) and metallic element B (which is at least one metallic element selected from the group consisting of Ti, Nb, Ta, W, Mo, Fe, Co and Cr), wherein it contains metal alkoxides of Bi, metallic element A (A as defined hereabove) and metallic element B (B as defined hereabove) respectively, and contains composite metal alkoxides formed by any two or more of said metal alkoxides.

A process for producing a ferroelectric capacitor by the steps of:

• (I) forming an electrode over a substrate;
• (II) applying a coating solution for use in forming a ferroelectric thin film onto said electrode;
• (III) annealing the applied coating to form a ferroelectric thin film;
• and
• (IV) forming an electrode over said ferroelectric thin film;
• wherein said process uses, as said coating solution for use in forming ferroelectric thin films, a Bi-based coating solution for use in forming ferroelectric thin films, containing Bi, metallic element A (which is at least one metallic element selected from the group consisting of Bi, Pb, Ba, Sr, Ca, Na, K and rare earth elements) and metallic element B (which is at least one metallic element selected from the group consisting of Ti, Nb, Ta, W, Mo, Fe, Co and Cr), wherein it contains metal alkoxides of Bi, metallic element A (A as defined hereabove) and metallic element B (B as defined hereabove) respectively, and contains composite metal alkoxides formed by any two or more of said metal alkoxides.