a case;

a cover plate coupled to a top of the case and having an upper plate that is configured to support a target object;

a thin film disposed on a top of the upper plate, a bottom of the upper plate, or a combination of both and configured be inductively heated by a working coil based on a material of the target object, the working coil being provided in the case and configured to inductively heat the thin film, the target object, or a combination of both;

a memory storing information on one or more correlations between (i) a temperature of the thin film and (ii) an inductor component and a resistor component of an equivalent circuit, the equivalent circuit being formed by the thin film based on the thin film being inductively heated by the working coil; and

a controller configured to operate the working coil and determine estimated temperature information corresponding to the inductor component and the resistor component of the equivalent circuit,

wherein the controller is configured to determine an estimated temperature associated with the determined estimated temperature information as a current temperature of the thin film based on the information on the one or more correlations without using a temperature sensor measuring the temperature of the thin film, and

wherein a thickness of the thin film is less than a skin depth of the thin film to thereby allow a magnetic field of the working coil to pass through the thin film and reach the target object.