Study On The Permeability Frequency Characteristics Regulation Of NiFe Film And Its Application

As a basic component in the circuit,it has become an inevitable trend to maintaining high performance while reduce the size of inductors through semiconductor processing technology.For this reason,three kinds of anisotropy control methods（external magnetic field deposition,oblique deposition and patterning）were studied,and NiFe thin film was prepared by electron beam evaporation.Then,the thin film inductance simulation optimization,physical development and test analysis are carried out based on the prepared NiFe film.In terms of thin films,effects of three anisotropy control methods on anisotropy and resonance frequency of NiFe thin films were studied from microstructure and magnetic properties.In terms of inductance,according to the performance of the optimized NiFe film,a planar spiral inductor and a runway inductor model were established,and they were simulated and optimized respectively.Finally,the performance of inductor was tested and analyzed.Firstly,the effects of three anisotropy control methods on anisotropy and resonance frequency of the film are investigated.The results show:（1）With applying a magnetic field during the deposition process,the film hysteresis loop shows obvious preferred orientation,and there is a certain increase in the anisotropy and resonance frequency.（2）Oblique deposition can effectively regulate the magnetic properties of thin films.In particular,as the oblique angle increases from 0°to 40°,resonance frequency increases from 0.75 GHz to 3.67 GHz.（3）The film is divided into strips with different spacing,width and length by lithography technology.Interaction between strips and shape anisotropy are introduced into the film,so as to realize the regulation of anisotropy of the film.It is worth noting that when the spacing is 30μm,the width is 60μm and the length is 1 mm,two resonance peaks appear in the magnetic spectrum of the film.Secondly,based on the regulated NiFe film,the planar spiral inductor and runway inductor were simulated and optimized by COMSOL.The effects of coil geometry,polyimide thickness and different substrates on the performance of film inductors were investigated.The optimized parameters of the planar spiral inductor are:coil width and spacing is 20μm,coil thickness is 10μm,coil turns is 22 turns,thickness of the polyimide layer is 20μm,the NiFe film is prepared by the inclined 10°deposition,bandwidth of quality factor Q>15 is 155 MHz,the inductance value is 355 n H（1 MHz）,and the cut-off frequency f₀ is above 340 MHz;the optimized parameters of the runway inductor are:coil width and spacing is 30μm,coil thickness is 10μm,inner width of the coil is 3 mm,coil turns are 9 turns,bandwidth of quality factor Q>15 is 100 MHz,the inductance value is363 n H（1 MHz）,and the cut-off frequency f₀ is above 250 MHz.Finally,based on the processing conditions,the inductors were prepared and tested.The result shows that the inductance of the thin film inductor is about 10%higher than that of the air-core inductor at 10 MHz,and the cut-off frequencies of both inductors are higher than 150 MHz.