《薄膜制备与分析》PPT课件.ppt

薄膜制备与表面分析Thin Film Synthesis and Surface AnalysisQing-Yu ZhangState Key Laboratory for Materials Modification by Laser,Ion and Electron Beams概论 表面及表面科学 v固体的表面、或者说界面，固体的表面、或者说界面，在人们的社在人们的社会实践中起着极为重要的作用。会实践中起着极为重要的作用。v表面科学的研究，对整个科学技术的发表面科学的研究，对整个科学技术的发展具有重要的意义。展具有重要的意义。v表面科学包括表面物理、表面化学、表表面科学包括表面物理、表面化学、表面电子学、表面生物学等。面电子学、表面生物学等。概论 表面及表面科学v固体表面：物体与真空或气体的界面。固体表面：物体与真空或气体的界面。v固固体体表表面面可可以以指指从从单单一一的的第第一一个个原原子子层层到到几几个个原原子子层层厚厚度度的的表表面面层层，甚甚至至深深达达几几个个微米的表面层。微米的表面层。v在热力学平衡的条件下，固体表面的化学在热力学平衡的条件下，固体表面的化学组成、微观结构、原子振动状态等均会与组成、微观结构、原子振动状态等均会与固体内部产生一定的差异。固体内部产生一定的差异。概论 表面及表面科学 Since it requires energy to terminate the bonding,the surface is energetically less stable than the bulk.This energy is known as the surface free energy.In the case of liquid interfaces,this energy is called surface tension.概论 表面分析技术 v表表面面分分析析技技术术是是人人们们为为了了获获取取表表面面的的物物理理、化化学学等等方方面面的的信信息息而而采采用用的的一一些些实实验验方方法法和手段。和手段。SampleExcitationsourceEnergy SelectorSignal DetectorEvent概论 表面分析技术v一一般般地地说说，它它是是利利用用一一种种探探测测束束如如电电子子束束、离离子子束束、光光子子束束、中中性性粒粒子子束束等等，有有时时还还加加上上电电场场、磁磁场场、热热等等的的作作用用，来来探探测测材材料料的的形形貌貌、化化学学组组成成、原原子子结结构构、原原子子状状态态、电电子子状状态态等等方方面面的的信息。信息。概论 表面分析技术探测粒子探测粒子 发射粒子发射粒子分析方法名称分析方法名称简称简称 主要用途主要用途 e e低能电子衍射低能电子衍射 LEED结构结构e e反射式高能电子衍射反射式高能电子衍射 RHEED结构结构e e俄歇电子能谱俄歇电子能谱 AES成分成分e e扫描俄歇探针扫描俄歇探针 SAM微区成分微区成分e e电离损失谱电离损失谱 ILS成分成分e 能量弥散能量弥散x射线谱射线谱 EDXS成分成分e e俄歇电子出现电势谱俄歇电子出现电势谱 AEAPS成分成分e 软软x射线出现电势谱射线出现电势谱SXAPS成分成分e e消隐电势谱消隐电势谱DAPS成分成分e e电子能量损失谱电子能量损失谱EELS原子及电子态原子及电子态e I电子诱导脱附电子诱导脱附ESD吸附原子态及成分吸附原子态及成分e e透射电子显微镜透射电子显微镜TEM形貌形貌e e扫描电子显微镜扫描电子显微镜SEM形貌形貌ee扫描透射电子显微镜扫描透射电子显微镜STEM形貌形貌概论 表面分析技术探测粒子探测粒子 发射粒子发射粒子分析方法名称分析方法名称简称简称 主要用途主要用途 I I离子探针质量分析离子探针质量分析IMMA微区成分微区成分I I静态次级离子质谱静态次级离子质谱SSIMS成分成分I n次级中性离子质谱次级中性离子质谱SNMS成分成分I I离子散射谱离子散射谱ISS成分、结构成分、结构I I卢瑟福背散射谱卢瑟福背散射谱RBS成分、结构成分、结构I e离子中和谱离子中和谱INS最表层电子态最表层电子态I 离子激发离子激发x射线谱射线谱IEXS原子及电子态原子及电子态概论 表面分析技术探测粒探测粒子子 发射粒子发射粒子分析方法名称分析方法名称简称简称 主要用途主要用途 ex射线光电子谱射线光电子谱XPS成分、化合态成分、化合态 e紫外线光电子谱紫外线光电子谱UPS分子及固体电子态分子及固体电子态 e同步辐射光电子谱同步辐射光电子谱SRPES成分、原子及电子态成分、原子及电子态 红外吸收谱红外吸收谱IR原子态原子态 拉曼散射谱拉曼散射谱RAMAN原子态原子态 扩展扩展x射线吸收谱精细结构射线吸收谱精细结构SEXAFS结构结构 角分辨光电子谱角分辨光电子谱ARPES原子及电子态结构原子及电子态结构 I光子诱导脱附谱光子诱导脱附谱PSD原子态原子态概论 表面分析技术探测粒子探测粒子 发射粒子发射粒子分析方法名称分析方法名称简称简称 主要用途主要用途 Ee场电子显微镜场电子显微镜FEM结构结构EI场离子显微镜场离子显微镜FIM结构结构EI场离子显微镜场离子显微镜-原子探针原子探针AP-FIM结构及成分结构及成分Ee场电子发射能量分布场电子发射能量分布FEED电子态电子态Ee扫描隧道显微镜扫描隧道显微镜STM形貌形貌Tn热脱附谱热脱附谱TDS原子态原子态n 中性粒子碰撞诱导辐射中性粒子碰撞诱导辐射SCANIIR成分成分n n分子束散射分子束散射MBS结构、原子态结构、原子态AWAW声显微镜声显微镜AM形貌形貌概论 表面分析技术部分表面分析设备的分析范围部分表面分析设备的分析范围 概论 表面分析技术XPS AES ILS ISS RBS SIMS 测氢测氢 NoNoNoNoNoYes元素灵敏度均匀性元素灵敏度均匀性 GoodGoodBadGoodGoodBad最小可检测灵敏度最小可检测灵敏度 10-2-10-310-2-10-310-910-2-10-310-2-10-310-4-10-5定量分析定量分析 GoodYesBadBadGoodBad化学态判断化学态判断 GoodYesYesBadBadBad谱峰分辨率谱峰分辨率 GoodGoodGoodBadBadGood识谱难易识谱难易 GoodGoodGood-表面探测深度表面探测深度 MLsMLsMLsMLML-mML-MLs空间分辨率空间分辨率 BadGoodGoodBadBadGood无损检测无损检测 YesYesYesNoYesYes理论数据完整性理论数据完整性 GoodYesBadYesGoodBad概论 真空技术原理v为为了了使使被被研研究究的的样样品品不不被被周周围围气气氛氛所所污污染染，获获取取“原原子子清清洁洁”的的表表面面，表表面面分分析析过过程程往往往往是是在在真真空空或或超超高高真真空空中中进进行行的的。目目前前，人人们们所所广广泛泛使使用用的的很很多多表表面面分析设备都具有真空系统。分析设备都具有真空系统。v薄膜制备设备往往涉及真空系统。薄膜制备设备往往涉及真空系统。概论 真空技术原理v真空单位真空单位qAtmospheres(atm):Scale relative to our atmospheric pressure as 1 atmqPascal(Pa):SI unit equal to N/m2qmBar:Equal to 1x10-8 Pa.qTorr or mmHg:Most commonly used pressure unit,based on mercury vacuum gauges.概论 真空技术原理v真空的划分真空的划分Atmospheric:760 TorrLow Vacuum:1 to 1x10-3 TorrMedium Vacuum:1x10-3 to 1x10-5 TorrHigh Vacuum(HV):1x10-6 to 1x10-8 TorrUltra-High Vacuum(UHV):200 C to remove adsorbed gasesSimple,inexpensive,oil-free概论 真空技术原理v真空的获得真空的获得Momentum transfer to gas molecules through collision with directed jet of oil moleculesRequire cooling water,backing pump10-3 to 10-7 Torr(to 10-9 Torr with LN2 cooling)qAdvantagesRobustHigh pumping speed for relatively low cost.No vibration or noise.qDisadvantagesOil as a pumping medium,high risk of back-streaming oil,cold traps requiredPotential for serious vacuum problems概论 真空技术原理v真空的获得真空的获得Molecules mechanically pumped by collision with angled high speed turbine blades(rotor).Several rotor arranged in a series spinning at 30,000-60,000 rpm.Rotor tangential velocity is on the order of the average thermal velocity of molecules.Atmosphere to 10-10 TorrOil/grease/electromagnetic bearingsMost common HV/UHV pump.概论 真空技术原理v真空的获得真空的获得qAdvantagesCorrectly operated they do not back-stream oil into the vacuum system at any time.They can be started and stopped in a few minutes time.qDisadvantage Turbo pump can be noisy and they induce vibration.Turbo pumps are expensive.概论 真空技术原理v真空的获得真空的获得High voltage between anode and cathode(5 kV)Electrons are captured in anode and spiral due the to magnetic field(longer path-length).Gas molecules are ionized by collisions with electrons and are accelerated to cathode.Ions embedded in cathode material(titanium)and sputter titanium atoms from surface.Sputtered Ti atoms act as getter for reactive gases.10-4 Torr to 10-11 Torr概论 真空技术原理v真空的获得真空的获得qAdvantagesClean,oil-free.No moving parts,no vibrations,quiet.Low power consumption and relatively long operating livesqDisadvantage Do not pump noble gases well.Requires“regeneration”of Ti every 4-6 years.概论 真空技术原理v真空的获得真空的获得Heated Ti filament evaporates Ti film onto cooled surface.Ti getters reactive gases by reaction.Operate at 10-8-10-11 TorrInexpensive,reliablePeriodic operation-not primary pumping mechanism概论 真空技术原理v真空的获得真空的获得Materials ConsiderationsOutgassing rates Producing“virtual”leaks Mechanical stability Temperature stabilityConductivity Chemical inertness Weldability概论 真空技术原理v真空的获得真空的获得Oxygen free high-purity copper(OFHC)Be-Cu alloyTantalum,Molybdenum,Tungsten Teflon(gassy)MACOR(machinable glass composite)Alumina Quartz,pyrex(gassy)mu-metal magnetic shielding(Co,Ni,Fe)Molybdenum disulfide(lubricant)Compatible Materials 概论 真空技术原理Materials to be Avoided(high vapor pressures)Zn,Cd:especially be careful of fasteners,bolts Brass Certain soldersAny type of grease or oilsv真空的获得真空的获得Common Vacuum ProblemsImproper cleaning or handling techniquesUsing incompatible materialsLeaksVirtual leaks 概论 真空技术原理v真空的获得真空的获得概论 真空技术原理v真空的获得真空的获得概论 真空技术原理v真空的获得真空的获得Pump DownTypically follows a well-defined sequence according to the types of pumps on the vacuum systemFor UHV systems,typically requires a few hours to reach a medium vacuum after a vent to airBake OutHeat the chamber to temperatures between 100oC and 200oC for 1-2 days.Rapidly remove adsorbed gases from the chamber walls at high temperatures in order to lower the outgassing rates at room temperature.Generally it takes another day to cool and recover base pressure.概论 真空技术原理v真空的测量真空的测量Heat filament with a constant current.Measure filament temperature with thermocouple.Gas molecules collide with and cool the filament.Voltage increases to keep filament at constant current.Atm to 10-4 TorrFast,simple,inexpensive.Thermocouple Gauge概论 真空技术原理v真空的测量真空的测量Two identical heated filaments;one sealed at HV,one exposed to system.Current flows through Wheatstone bridge circuit.Pressure difference indicated by meter(non-linear).Atm to 10-4 torr.Simple,reliable,inexpensive.Pirani Gauge概论 真空技术原理v真空的测量真空的测量Heated filament produces electrons via thermionic emission.Electrons are accelerated towards anode grid.Many electrons pass through the grid and create positive ions from collisions with gas molecules.Ions are accelerated to collector wire.Measure the current between anode and collector.Operate at 10-4 to 10-11 TorrSensitive,high accuracy,widely used.Ion Gauge(Bayard-Alpert)概论 真空技术原理v真空的测量真空的测量Quadrupole mass spectrometer-RGA(residual gas analyzer)10-4 to 10-14 torrTotal pressure mode integrates all ion intensitiesPartial pressure mode indicates residual vacuum compositionHighly accurate,preciseComplex,expensive.Mass Spectrometer概论 真空技术原理v真空的测量真空的测量Typical UHV mass spectrum of background gases after bakeout.H2OCO2N2H2Leak ratesFlangesVirtual leaksOutgassing ratesContaminantsMaterialsSamplesPumping RatesType of pumpsType of gases being pumped概论 真空技术原理v真空的测量真空的测量Typical UHV mass spectrum of residual gases before bakeout.