文档介绍：该【扫描电子显微术：例子 】是由【博大精深】上传分享，文档一共【37】页，该文档可以免费在线阅读，需要了解更多关于【扫描电子显微术：例子 】的内容，可以使用淘豆网的站内搜索功能，选择自己适合的文档，以下文字是截取该文章内的部分文字，如需要获得完整电子版，请下载此文档到您的设备，方便您编辑和打印。扫描电电子显显微术术:例例子
TheeffectofAcceleratingVoltageonSEMImages
30kV
10kV
5kV
3kV
Specimen:Toner墨墨粉粉
Whenhighacceleratingvoltageisusedasat(a),it
ishardtoobtainthecontrastofthespecimensurface
,thespecimensurfaceiseasily
seenat(b).
(a)30kVx2,500
(b)5kVx2,500
Specimen:EvaporatedAuparticles.
Theimagesharpnessandresolutionarebetter
atthehigheracceleratingvoltage,25kV.
(a)5kVx36,000
(b)25kVx36,000
Specimen:Filterpaper.
At5kV,themicrostructuresofthespecimen
surfaceareclearlyseenasthepenetrationand
diffusionareaofincidentelectronsisshallow.
(a)5kVx1,400
(b)25kVx1,400
:Sinteredpowder.
Atlowacceleratingvoltage,whilesurfacemicrostructures
canbeobserved,itisdifficulttoobtainsharpmicrographs
,clearimagescan
beobtainedbyshorteningtheWDorreducingtheelectron
probediameter.
(a)5kVx7,200
(b)25kVx7,200
Specimen:Paintcoat.
Whenahighacceleratingvoltageisused,morescattered
electronsareproducedfromtheconstituentsubstances
ofsurfacemicrostructures,butproducesadifferent
contrastduetobackscatteredelectronsfromthe
substanceswithinthespecimen.
(a)5kVx2,200
(b)25kVx2,200
SE(secondaryelectron)imaging
Highresolution(betterthan5nm)isobtainablewithmostSEM’s
Betterthan2nmresolutionispossibleinsomecases
10nmresolutionisveryroutine(unlessthesamplelimitstheresolution,asisoftenthecase)
Edgeeffect(secondaryelectronemissiondifferingwithsurfacecondition).
Influenceofedgeeffectonimagequality
Amongthecontrastfactorsforsecondaryelectrons,’sincidentangleonthespecimensurface,andthehighertheangle,.
Therearemanyslantsalloverthem,,largequantitiesofsecondaryelectronsaregeneratedfromtheprotrusionsandthecircumferencesofobjectsonthespecimensurface,causingthemtoappearbrighterthanevenportions.
SpecimenICchip.
Thehighertheacceleratingvoltage,thegreateristhe
edgeeffect,makingtheedgesbrighter.
Influenceofedgeeffectonimagequality
,thelowertheacceleratingvoltage,,thusresultinginthemicrostructurespresentinthembeingseenmoreclearly.
Normally,,ifthetiltdirectionofthespecimensurfaceandthepositionofthesecondaryelectrondetectoraregeometricallyinagreementwitheachother,morebackscatteredelectronsfromthetiltedportionsaremixed,causingthemtobeseenmorebrightlyduetosynergism.
(a)5kVx720TiltAngle:50°
(b)25kVx720TiltAngle:50°
Specimen:ICchip.
5kVx1,100
Thesidesofpatternsareviewedbytiltingthespecimen.
Theamountofsignalsisincreased.
Useofspecimentilt:a)Dependenceofimagequalityontiltangle
1)Improvingthequalityofsecondaryelectronimages;2)Obtaininginformationdifferentformthatobtainedwhenthespecimenisnottilted,thatis,)Obtainingstereomicrographs.
°°(a)andaphototakenat45°(b).,,etc.,therefore,itisnecessarytomeasurewithoutspecimentiltingortocorrectvaluesobtainedformatiltedstate.
(a)Tiltangle:0°
(b)Tiltangle:45°°