纳米材料和纳米结构第七讲.ppt
![资源得分’ title=](/images/score_1.gif)
![资源得分’ title=](/images/score_1.gif)
![资源得分’ title=](/images/score_1.gif)
![资源得分’ title=](/images/score_1.gif)
![资源得分’ title=](/images/score_05.gif)
《纳米材料和纳米结构第七讲.ppt》由会员分享,可在线阅读,更多相关《纳米材料和纳米结构第七讲.ppt(45页珍藏版)》请在淘文阁 - 分享文档赚钱的网站上搜索。
1、第七讲第七讲第七讲第七讲Physical Vapor Deposition物理气相沉积物理气相沉积纳米材料和纳米结构纳米材料和纳米结构纳米材料和纳米结构纳米材料和纳米结构Physical Vapor Deposition(PVD)wDefinition Film deposition by condensation from vapor phasewThree Steps of PVDGenerating a vapor phase by evaporation or sublimation Electron-beam evaporation Molecular-beam epitaxy Th
2、ermal evaporation Sputtering Cathodic arc plasma deposition Pulsed laser depositionTransporting the material from the source to the substrateFormation of film by nucleation and diffusionwApplicationCoatings of electronic materialsInsulatorSemiconductorConductorSuperconductorNanometer scale multilaye
3、r structuresAdvanced electronic devicesAbrasion resistant coatingswConcerned Problems and ChallengesContamination at the interfaces or intermixingMulti-material systems involvedCost of equipment and maintenance Complexion of operationwSystems Described in This SectionSputteringPulsed laser depositio
4、n1 Sputtering(溅射)(溅射)1-1 Principle of Sputtering1-2 Sputtering System1-3 Preparing Multilayer Structures by Sputtering1-4 Current Status of Sputtering1-1 Principle of SputteringwEjection of Atoms from the TargetEnergetic particles bombarding a target surface with sufficient energy(50 eV 1000 eV)wTar
5、getCathode,connected to a negative voltage supplyComposed of the materials to be depositedwSubstrateAnode May be grounded,floated,or biasedwGlow Discharge Medium in Sputtering ChamberA gas or a mixture of different gases,most commonly Ar or HeIn reactive sputtering:introduce reactive gases such as O
6、2 or N2 Pressure:a few mTorr to several hundreds mTorrwProcedureGeneration of positive ions:ionizing the sputtering gas by glow dischargeBombarding:accelerated positive ions to strike the target surface and remove mainly neutral atomsCondensation:neutral atoms leave the target and condense on the su
7、bstrate surface,and form into thin films wAn Important Concept:Sputtering YieldA measurement of the efficiency of sputteringRatio of the number of emitted particles to the number of bombarding ones 1-2 Sputtering SystemwTypical Types of Sputtering SystemsDirect current(dc)diode sputteringUsed for sp
8、uttering conducting materialsRadio frequency(rf)diode sputteringUsed for sputtering insulating materialsMagnetron diode sputtering Most commonly used todayPlasma be confined around the target surface by a magnet fieldAdvantages of using magnetron sputteringlFeasibility of large cathode sizelHigh spu
9、ttering yieldlLess bombardment to the substrate用于用于制备制备TiN/VN 多多层膜层膜的磁的磁控溅控溅射系射系统统氩气氩气流量表流量表流量控制阀流量控制阀压力传感器压力传感器低温泵低温泵低温泵低温泵靶靶1靶靶2旋转衬底支架旋转衬底支架衬底衬底流量表流量表阀门阀门流量表流量表流量控制阀流量控制阀1流量控制阀流量控制阀2主流量控制阀主流量控制阀质谱仪质谱仪阀门阀门锁定装置锁定装置wWays to reduce the damage and re-sputtering of growing filmDamage caused by negative
10、ion effect and radiation enhanced diffusionImprovement methodUse high gas pressure:to reduce the energy of the negative ionsUse off-axis sputtering:to avoid the substrate directly facing the cathode Disadvantage of off-axis sputtering:llow deposition ratelsmall deposition areawDeposition of magnetic
11、 materials:facing target sputtering systems偏轴溅射系统偏轴溅射系统示意图示意图Schematic of off-axis sputtering system可可360度旋转的衬底支架度旋转的衬底支架陶瓷加热器陶瓷加热器负离子撞击区负离子撞击区衬底衬底靶靶溅射枪溅射枪溅射源溅射源屏蔽闸屏蔽闸空间屏蔽区空间屏蔽区正面溅射系统正面溅射系统示意图示意图Schematic of the facing target sputtering system衬底衬底靶靶磁体磁体冷却水冷却水氩气氩气1-3 Preparing Multilayer Structures b
12、y SputteringwTypes and Properties of Multilayer StructuresTypes of architecturesMetal/metalCeramic/ceramicMetal/ceramicSemiconductor/semiconductorStructural and physical propertiesWith structurally modulated architecturesWith compositionally modulated architecturesHigh interface volume fractionLarge
13、 intrinsic stressWith structural and/or compositional gradientExhibiting unique and enhanced electric,dielectric,magnetic,and mechanic propertieswBaTiO3 Nanolayer Ferroelectric Thin Film CapacitorsAdvantage:higher relative dielectric constantDisadvantage:high leakage currentElectrical properties str
14、ongly depending upon the processing condition,microcrystal structure,and choice of bottom electrodeAmorphous:low dielectric constant(16 at 105 V/cm),low leakage currentPolycrystalline:high dielectric constant(400 at 105 V/cm),high leakage currentAim of nanolayer structure BaTiO3 film capacitor:high
15、dielectric constant and low leakage currentRealization and effectsSubstrate:Ru/SiO2/SiTechnique:rf magnetron sputtering,sputtering interruption between layers to change the substrate temperatures(680 C C,60 C C)Layer structure:n-cycle alternate layers of amorphous and polycrystalline BaTiO3(microcry
16、stalline be obtained by annealing amorphous layer)Results obtainedlLeakage current density be considerably reduced,and the effect becoming better with increasing cycle numberlDielectric constant be two or three times higher than single amorphous layer but lower than a single polycrystalline layer具有纳
17、米多层结构的具有纳米多层结构的BaTiO3薄膜电容器横截面示意图薄膜电容器横截面示意图wNanolayer MoSi2/SiCSubstrate:single crystal silicon(sc-Si)Techniques:Magnetron sputtering for deposition of MoSi2rf sputtering for deposition of SiCMoSi2/SiC layered composites be prepared by cyclically passing the samples beneath the two targets with a sp
18、eed(thickness of 10 nm/3 nm)Heat treatment or annealing:inducing recrystallization in the MoSi2/SiC multilayered filmProperties after annealing:Superior oxidation resistanceSignificant hardness MoSi2/SiC多层膜的剖面透射电镜图片多层膜的剖面透射电镜图片Cross-sectional TEM image of MoSi2/SiC multilayered filmMoSi2/SiC多层膜退火前的电
19、子衍射花样多层膜退火前的电子衍射花样Electron Diffraction Pattern of MoSi2/SiC multilayered film before annealing经过经过800C,1h退火处理的退火处理的MoSi2/SiC多层膜多层膜的低放大倍数亮场电镜照片的低放大倍数亮场电镜照片wNanolayer Cu/NbSubstrate:(100)sc-SiTechniques:dc magnetron sputteringLayer thickness:(100 nm/100nm)Properties:wHigh strengthwSuperior thermal con
- 配套讲稿:
如PPT文件的首页显示word图标,表示该PPT已包含配套word讲稿。双击word图标可打开word文档。
- 特殊限制:
部分文档作品中含有的国旗、国徽等图片,仅作为作品整体效果示例展示,禁止商用。设计者仅对作品中独创性部分享有著作权。
- 关 键 词:
- 纳米 材料 结构 第七
![提示](https://www.taowenge.com/images/bang_tan.gif)
限制150内