Method for fabricating ferro-electric thin films using a sol-gel technique

Abstract

A method is disclosed for the formation of ferro-electric films using a multi coating process based on a sol-gel technique. In particular a method is disclosed to fabricate high-quality thickness scaled PZT films of an alkoxide-type liquid chemical PZT precursor solution, preferably a Pb(Zr x Ti 1−x )O 3 precursor solution, using a sol-gel technique. At least two coated layers are deposited, but the precise number of coated layers depends on the desired thickness of the ferro-electric film. According to the method of the invention, the electrical characteristics of the film as formed are not dependent on the number of coated layers. There are a number of properties, characteristic for the method of the present invention, and resulting in said excellent electrical characteristics. In fact said method can comprise a multi coating process wherein a reduced number of coated layers is used but where intermediate crystallization steps are performed. The ferro-electric films formed using this method have excellent electrical characteristics, provided that a crystallization step is only performed if the thickness of the film formed since the last crystallization step is minimum about 40 to 50 nm. Alternatively, the method can comprise a multi coating process wherein no intermediate crystallization steps are used.

What is claimed is:  
     
         1 . A Pb(Zr x Ti 1−x )O 3  precursor solution for ferro-electric thin film fabrication, x having a value in the range from 0.1 to 0.4, said precursor solution being prepared by mixing dehydrated lead acetate with at least one alkoxide in butoxyethanol, said precursor solution comprising polymeric structures having a mass fractal dimension equal to or smaller than 2, and said precursor solution being diluted in butoxyethanol.