Ferroelectric thin-film production method, voltage-application etching apparatus, ferroelectric crystal thin-film substrate, and ferroelectric crystal wafer

A voltage-application etching apparatus used in an etching process and a voltage applying process in a ferroelectric thin-film production method comprising:

• an etching process of dipping one surface in an etching solution to thereby etch the one surface, with respect to a ferroelectric crystal which has the one surface and another surface that face each other and in which an etching rate of the one surface is greater than an etching rate of the another surface in such a condition that polarization directions are oriented in one direction;
• and a voltage applying process of applying a predetermined voltage between the one surface and the another surface,
• said voltage-application etching apparatus comprising:
• a container to dip the one surface in the etching solution;
• a sealing device for sealing a portion other than the one surface from the etching solution;
• a power supply for applying the predetermined voltage between the one surface and the another surface;
• a first connecting device for electrically connecting one output terminal of said power supply with the one surface;
• and
• a second connecting device for electrically connecting another output terminal of said power supply with the another surface.

A ferroelectric crystal thin-film substrate comprising:

• a substrate;
• an electrode formed on the substrate;
• and
• a ferroelectric crystal which is formed on the electrode and which is less than 1 μm in thickness, wherein
• an area size of an entire surface of the substrate is equal to or greater than 10 mm2.

A ferroelectric crystal wafer comprising:

• a substrate;
• an electrode formed on the substrate;
• and
• a ferroelectric crystal which is formed on the electrode and which is less than 1 μm in thickness.