1、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 substrate surface,a
2、nd 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 sputtering conducti
3、ng 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 sputtering yieldlLes
4、s 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 ion effect and ra
5、diation 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 materials:facing
6、 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 by SputteringwType
7、s and Properties of Multilayer StructuresTypes of architecturesMetal/metalCeramic/ceramicMetal/ceramicSemiconductor/semiconductorStructural and physical propertiesWith structurally modulated architecturesWith compositionally modulated architecturesHigh interface volume fractionLarge intrinsic stress
8、With 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 strongly depending u
9、pon 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 dielectric consta
10、nt 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(microcrystalline be obtai
11、ned 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/Si
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