A decoupling calculation method of separating temperature component from the nano-scale metal film thickness measurement output by the eddy current sensor

Abstract

The eddy current method has been widely applied in the field of micro and nano metal film thickness detection. The output signal of an eddy current sensor is generally tiny in practice, and it is easily affected by the ambient temperature variation, which results in a decrease in the measurement accuracy. How to separate temperature effect on film thickness measurement for achieving a high precision is a major problem. Therefore, a coupling model with an electromagnetic field and a temperature field is established in this study, and the influence of the film thickness and temperature on coil impedance is calculated. It is found that the inductance and resistance of the coil vary monotonically as thickness and temperature with a measure of linearity in a certain range, as well as the real part and imaginary part of the output voltage based on the AC bridge. Thereby a film thickness-temperature decoupling method is proposed, and the different linear calibration intervals are further divided considering the linearity and measurement accuracy. According to a series of calculation results, it is confirmed that the method can decouple the two, and accomplish a higher accuracy. At the same time, it is feasible to achieve a synchronous detection of the metal film thickness and the ambient temperature in a certain range by using the proposed method.

Research on indoor and outdoor positioning switching algorithm based on improved PSO-BP

“…In recent years, with the development of modern information technology such as embedded technology and communication technology, the positioning technology in weak signal environment and confined space has also been developed to a certain extent [1]. Positioning and location services play an important role in the development of new information-based strategic emerging industries, and are the basic support for many key technologies in the fields of Internet of Things, intelligent transportation and smart cities [2].…”