Research On The Integration Of High Frequency Soft Magnetic Film And Integrated Circuit Micromagnetic Chip Inductor

With the rapid development of science and technology and the electronic information industry,the technological innovation of integrated circuits is facing new challenges.As a result,it is vital that to explore the corresponding electronic parts and components to meet requirements of technological development.As one of the three passive devices,inductors are widely applied in integrated circuits,especially in high frequency circuits and wireless communication fields.For example,inductors are indispensable in transformers,oscillators,and supply voltage converters.However,the traditional planar spiral inductors can't meet the development trend of high frequency and integration of components because they occupy large areas of chips and their performance deteriorates seriously at high frequency.Soft magnetic materials have the characteristics of high saturation magnetization,low coercivity,high ferromagnetic resonance frequency and low loss,which meet the requirements of electronic parts and components to be developed in the direction of high frequency,miniaturization,high integration,low loss and high stability.The introduction of magnetic film as core material in planar spiral inductors can not only reduce the device size but also increase the inductance,and can effectively improve the performance of inductors at high frequencies.The application of microcore inductor paves the effective way for the development of integrated circuits.This paper aims to combine FeCoB trilayer films with planar spiral inductors to explore the performance of microcore inductors at high frequency.The main contents of this paper are as follows:(1)We simulated the planar spiral inductor and clarified the influence of different structural parameters on inductance L and quality factor Q by HFSS,a 3D electromagnetic field simulation software.This provides a theoretical basis for structural design and process optimization of inductors.(2)The trilayer films magnetic core material FeCoB/Ru/FeCoB were prepared by magnetron sputtering method,and the structure and high frequency properties of FeCoB/Ru/FeCoB were characterized.For the sample with FeCoB ferromagnetic layer thickness of 25 nm and Ru non-magnetic layer thickness of 0.3 nm,we obtained its ferromagnetic resonance frequency above 8.37 GHz and the magnetic conductivity above19.Hence,it is a good choice to be used as the magnetic core material of the micro magnetic core inductor.(3)In view of the problems in the process of preparing microcore inductors,reasonable improvement and optimization were carried out on the techniques of lithography,electroplating,magnetron sputtering,PI curing and etching.Finally,we explored the best process scheme of microcore inductors and successfully prepared two different types of inductances.(4)Two kinds of inductors have been tested by using vector network analyzer and microwave probe station.The test results show that the inductance L of the inductor with FeCoB/Ru/FeCoB is 1.37 n H when f= 1.36 GHz.Compared with the hollow core inductor with the same structure,the inductance increased by 37% and the maximum value of Q is4.9,a decrease of 19.7%.