Method for fabricating capacitor containing amorphous and polycrystalline ferroelectric films and method for forming amorphous ferroelectric film

A method for preparing a thin film capacitor, said method comprising the steps of:

• (a) preparing a bottom metal electrode;
• (b) growing an amorphous ferroelectric film on a surface of the bottom metal electrode by sputtering;
• (c) growing a polycrystalline ferroelectric film on the amorphous ferroelectric film;
• and
• (d) preparing an upper metal electrode on the polycrystalline ferroelectric film;
• wherein the amorphous ferroelectric film of step (b) is grown by sputtering in a reaction chamber under the following conditions of:
• a temperature in the reaction chamber being in the range of 25° C.-150° C.;
• a pressure in the reaction chamber being in the range of 5-100 mtorr;
• a flow rate of a working gas introduced into the reaction chamber being in the range of 10-80 SCCM;
• and
• a flow rate of a reactive gas introduced into the reaction chamber being in the range of 10-80 SCCM;
• wherein a ratio of the flow rate of the reactive gas and the flow rate of the working gas ranges between 0.25 and 1.0.