基于光学模共振的超晶格软磁厚膜及其IC微磁电感的整合

The high-frequency soft magnetic thick films can greatly reduce the dimension of micro-inductors, realizing their integration. The working frequency of integration circuit micro-magnetic inductors (IC-MMIs) is limited by the self-bias ferromagnetic resonance (FMR) frequency fr of soft magnetic films (SMFs). Currently, the acoustic mode resonance frequency (~10 GHz) of SMFs is difficult to be further improved. Therefore, a new mechanism should be explored for further enhancing the FMR frequency of SMFs. Very recently, we discovered practical optical-mode resonance (OMR) with FMR frequency higher than 18.1 GHz and high permeability in antiferromagnetically coupled FM/NM/FM trilayers with 50 nm in thickness. This discovery provides a possibility to fabricate IC-MMIs with ultra-high working frequency, and will be a new breakthrough point for ultra-high frequency IC-MMIs.. So in this project, firstly, we choose various ferromagnetic and nonferromagnetic materials, control the structure and process parameters of OMR trilayers, explore the influence factors of the permeability and resonance frequency in the OMR trilayer. At the same time, we construct a non-collinear magnetic configuration model and non-constant exchange coupling coefficient model to clarify the permeability mechanism in OMR trilayers. . Secondly, the quasi-isotropic or anisotropic superlattice thick films with perfect period and uniform high-frequency performances among the OMR units are carefully prepared. So that the pure optical mode resonance in soft magnetic thick films with high magnetic permeability, high ferromagnetic resonance frequency and low loss is obtained. The magnetic coupling mechanism among the ferromagnetic sublayers in OMR thick films will be figured out. . Thirdly, we will design micro-magnetic inductors using some micromagnetism and high-frequency structure simulation softwares, such as OOMMF, Maxwell and HFSS, etc. under the consideration of OMR thick films, and then integrate the superlattice thick films with the designed micro-magnetic inductors experimentally. As a consequence, the key integration technology will be summarized. . At last, high performance IC-MMIs based on OMR superlattice thick films with working frequency over 10 GHz will be fabricated and applied in IC products.

高频软磁厚膜可大幅减小微电感尺寸，实现电感元件的集成化。受声学模共振软磁膜自偏置铁磁共振频率fr（~10GHz）的限制，当前集成电路微磁电感（IC-MMIs）的工作频率较低。具有高频率特性的光学模共振（OMR）三层膜（厚度~50nm）fr>18.1GHz，将成为研制超高频IC-MMIs的突破口，但其磁导率来源、厚膜制备及其微磁电感整合等亟待深入研究。本项目将改变铁磁和非磁层材质、结构和工艺参数，探寻影响OMR薄膜磁导率和频率的因素，建立非共线磁构型模型和非常数型交换耦合系数模型，探明其磁导率机理；以OMR三层膜为基本单元，构建周期性好、各单元高频性能一致的超晶格结构厚膜，厘清其层间磁耦合机制，获得高磁导率低损耗的纯光学模共振；利用微磁学和微波仿真软件，探寻超晶格厚膜微磁电感的设计方法；探索超晶格厚膜与微电感的整合方法，获得整合关键技术，制造出10GHz以上基于OMR的高性能IC-MMIs。

本项目探索了光学模共振的产生和磁导率机理，构建了基于光学模共振的超高频超晶格多层膜，并获得了10 GHz以上超高频微磁电感。取得的主要研究成果如下：. 1. 光学模共振来源和磁导率机制。探索了铁磁层厚度、磁各向异性、磁构型，非磁层材质、厚度，层间耦合作用类型和强度，磁电耦合调控等多种因素对光学模共振的产生和增强的影响，揭示了光学模产生机理是内生磁各向异性和层间反铁磁耦合；频率增强机制是层间交换耦合强度；磁导率机制是磁矩取向度。通过精确控制非磁隔离层厚度，在FeCoB/Ru/FeCoB三层膜体系中获得FMR频率创纪录的高达22.68 GHz的自偏置纯光学模共振，为下一步构建超高频厚膜和微磁电感奠定了材料基础。. 2. 光学模共振超晶格厚膜的构建机制和制备方法。通过光学模共振单元间耦合机制的研究，厘清了超晶格厚膜的共振机理；通过磁耦合控制技术，构建了光学模共振单元（FeCoB/Ru/FeCoB反铁磁耦合三明治膜）内强耦合，单元与单元间退耦合的多层膜，解决了光学模共振厚膜的难题。采用5 nm的非磁ZnO作为耦合隔离层，以隔绝光学模共振单元之间的耦合，成功制备出同频共振的[(FeCoB/Ru/FeCoB)/ZnO]n超晶格厚膜，并得到了FMR频率高达18 GHz的单一光学模共振态，为制备微磁电感铺平了道路。. 3. 基于超高频光学模共振的微磁电感整合制备与性能提升。通过HFSS模拟、AutoCAD光罩模组设计、光刻微加工工艺等，将超晶格厚膜与电感整合，制备出平面型和Solenoid型两种类型的平面微磁电感，其频率高达10.9-13.4 GHz，电感量增量50%以上，Q因子也得到了较大的提高。本项目不仅利用光学模共振大幅提升了超高频电感的性能，同时也证明了光学模共振在超高频微波器件中应用的可行性。. 本项目在Adv. Funct. Mater.、Appl. Phys. Lett.等期刊发表论文26篇，引用159篇次；申请中国发明专利4项，其中授权中国发明专利3项；培养博士生5名，其中获得博士学位3名，硕士研究生30名，获得学位14名。