Research Of RF On-chip Inductors With Magnetic Films

On-chip passive inductor is one kind of important critical elements in radio frequency integrated circuits(RF ICs),but at present,super compact,high performance on-chip micro-inductor is still hard to achieve.Small chip size and high performance of the on-chip inductors are demanded with the continuous development of RF circuits.In this thesis,novel on-chip RF micro-inductor with back hollow structure is proposed.Furthermore,some magnetic materials have been introduced to the back hollow structure inductor to achieve the enhancement of the inductance,quality factor and self-resonance frequency of the on-chip inductor.What’s more,magnetic on-chip inductors with YIG ferrite have been investigated to obtain high frequency application.Π-type lumped equivalent circuits for conventional on-chip inductor and magnetic on-chip inductor are proposed,and its calculation formula are investigated.Furthermore,the equivalent circuits and calculation formula for back hollow structure inductor and YIG inductor have been achieved,and the influences of magnetic structures,meterial characterizations and device parameters on the inductor performance improvement are discussed.Based on the consideration of reducing the substrate loss thus to obtain high performance,back hollow structure inductor which the silicon beneath the inductor coils are etched directly is proposed.Research result indicates that the back hollow structure inductor can achieve the enhancement of 13% maximum quality factor Qmax,54% fmax and 38% self-resonance frequency f0.CoFeB/ZnO/CoFeB thin film was added to RF back hollow inductor to improve the inductor performance.The Co Fe B/Zn O/Co Fe B magnetic inductor has achieved 41.2%-70.6% improvement of inductance across 0 – 8 GHz and 3%-18% enhancement of Q-factor from 0 to 3.8 GHz.In order to meet the needs of high-frequency applications,this paper also designed on-chip RF ferrite inductors with YIG ferrite.The YIG ferrite film epitaxially grown on GGG substrate with high quality.Compared to other works,the application frequency of the YIG ferrite on-chip inductor has been achieved nearly 400% improvement,what’s more,the most suitable operating frequency of the YIG ferrite on-chip inductor reached 7.5GHz.