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The Preparation Of YIG Films Used For Circulator By Radio Frequency Magnetron Sputtering

Posted on:2015-01-13Degree:MasterType:Thesis
Country:ChinaCandidate:X F YanFull Text:PDF
GTID:2268330428965140Subject:Microelectronics and Solid State Electronics
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Circulator is one kind of widely used devices in microwave communication. Withthe rapid development of the microwave communication system, it is necessary tostudy the circulators with light weight, miniaturization, high performance and lowcost. Because of microstrip film circulators prepared by the ferrite film meet therequirements, they have been attracted by researchers around the world.As a representive of ferrimagnetic ferrite material, garnet ferrite (Y3Fe5O12) iswidely used to prepared circulators, because of its narrower ferromagnetic resonancelinewidth, higher resistivity, lower high frequency loss and better gyromagnetic effect.The performance of the circulator is determined by the quality of the ferrite films,therefore, it is necessary to research how to prepare high quality YIG films.This research prepared YIG films by radio frequency magnetron sputtering on Si,GGG, MgO and Al2O3substrate using the highly purified YIG target. The surfacetopography, crystallinity and saturation magnetization of target and films was detectedby SEM, XRD and VSM, respectively. Becides, the ferromagnetic resonancelinewidth and the content of Fe2+of the films was measured by EPR and XPS,respectively.This paper mianly discussed four section:(1) The influence of presinteringtemperature on YIG target, so that a group of YIG powders was presintered at1000oC,1200oC,1300oC and1400oC,respectively. The results suggested that the saturationmagnetization of target will decrease with increase of presintering temperature,then itwill increase to get maximum28.3emu/g at1400oC.(2) The different sputteringparameters, for example, sputtering powder, sputtering pressure, and the distancebetween target and substrate. Because of the limits of the instrument, parameters(100W,150W,200W),(0.3Pa,1Pa,5Pa,10Pa) and (10cm,11cm,12cm) was choosed.The results indicated that deposition rate was the largest when the powderis200W.The films sputtered at5Pa have the best crystallinity and the lowest content value21.56%of Fe2+. The films showed good crystallinity and the lowest ferromagneticresonance linewidth when the distance between target and substratewas11cm.(3) Thequality of films were affected by annealing parameters,such as tempreture, time andgas atmosphere.(650oC,750oC,850oC),(1h,4h,10h), and (air, oxygen) were choosed.The results displayed the film annealed at650oC did not crystallized and the film has the best crystalline when tempreture increased to750oC, but second phase YIPemerged when tempreture was above850oC. The sample annealed for4h has thebetter crystallinity and the narrower ferromagnetic resonance linewidth compared toother samples annealed for other time. The film only has YIP phase when the timewas above10h. The sample annealed in oxygen did not have little particles and hasbetter surface roughness.(4) Substrates, thickness of film and Ag buffer has effect onfilm quality. Films sputtered in different substrates suggested that the deposition rate80.7nm/h is largest when the substrate is Si and the film has the better surface. Theferromagnetic resonance linewidth is41Oe when the substrate is GGG. Theferromagnetic resonance linewidth of the film sputtered onSi is32Oe when the filmthickness is10μm. The XRD atlas of thick film sputterd on GGG substrate is nearlythe same as the target’s. In addition, the saturation magnetization was close tothebulk’s when the thickness is aroud10μm. The crystallinity and surface morphologywas improved when the film has Ag buffer.The results showed that the9.8μm film which prepared on Si substrate depositedat200W,5Pa and annealed at750oC for4h has the best overall property. Particles onsurface was in uniform size. Better crystallinity was detected. FRM linewidth32Oeand Ms129emu/cm3which is close to the bulk’s was observed.
Keywords/Search Tags:YIG, films, RF Sputtering, Circultor, Ferromagnetic resonance linewidth
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