Research On The Measurement Of The Electromagnetic Parameters Of Magnetic Thin Films

With the vigorous development of electronic information industry,magnetic thin films have been more and more widely used due to their ferromagnetism.The measurement of the electromagnetic parameters of magnetic thin film,especially the measurement of its complex permeability,has always been the hot spot of the research at home and abroad.However,the thickness of magnetic thin film is at micron or nanometer level,which brings great difficulty in testing accuracy and sensitivity.So how to measure the electromagnetic parameters at variable temperatures of magnetic thin film has important significance.At first,testing model respectively for the complex permittivity and complex magnetic permeability of magnetic thin film were set up,and then their calculation formulas were deduced.With the electromagnetic simulation software HFSS test fixtures were designed,and their performance was evaluated.After the test fixture were determined,a complete set of variable temperature system was developed-the heating system is used to implement high temperature environment ranging from room temperature to 100?,and the refrigeration system is used to implement low temperature environment ranging from-50? to room temperature.The test software was written based on VC++,which greatly simplifies the experimental operation and data processing.Then the interface of the software and the experimental steps were introduced in details.The magnetic thin film samples in this paper are covered on Si substrate with the physical size 0.5mm × 5mm × 15 mm,and the thickness is several hundred nanometers.With the test system developed in this paper,a few specifications of the samples were tested at normal temperature and variable temperatures.Then the precision and stability of the test results,and the temperature characteristic of electromagnetic parameters of magnetic thin film material were analyzed.Finally,the error analysis of the test results was carried on,and some advice for continuing to improve the whole test system was put forward.In this paper a unique design was made on the test fixture,which improved the system's test bandwidth(50MHz~12GHz).A short-ended microstrip line was designed to test the complex permeability of magnetic thin film,and an open-ended microstrip line was designed to test the complex permittivity of magnetic thin film.Test results show that the whole test system has enough stability and precision,and can completely satisfy the amount of testing requirements of magnetic thin film at variable temperature.