46a

Figure4.1(2e) (a)AbarentypeSiwafer.(b)AnoxidizedSiwaferbydryorwetoxidation.(c)Applicationofresist.

(d)Resistexposurethroughthemask.

46b

Figure4.2(2e) (a)Thewaferafterthedevelopment.(b)ThewaferafterSiO2 removal.(c)Thefinalresultafteracomplete

lithographyprocess.(d)Apn junctionisformedinthediffusionorimplantationprocess.(e)Thewaferafter

metalization.(f)Apn junctionafterthecompeteprocess.

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47a

Figure13.9. Detailsoftheopticallithographicpatterntransferprocess.8

47b

Figure13.19. Comparisonofwetchemicaletchinganddryetchingforpatterntransfer.22

47c

Figure12.2. Schematiccrosssectionofaresistanceheatedoxidationfurnace.

Figure12.4. (a)Basicstructuralunitofsilicondioxide.(b)Twodimensionalrepresentationofaquartzcrystallattice.

(c)Twodimensionalrepresentationoftheamorphousstructureofsilicondioxide.1

47d

Figure 1 3 Gro th of silicon dio ide b thermal o idationFigure12.3. Growthofsilicondioxidebythermaloxidation.

Figure12.5. Basicmodelforthethermaloxidationofsilicon.2

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Figure12.6. Linearrateconstantversustemperature.2

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Figure12.7. Parabolicrateconstantversustemperature.2

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Figure12.8. Experimentalresultsofsilicondioxidethicknessasafunctionofreactiontimeandtemperaturefortwosubstrateorienta

tions.(a)Growthindryoxygen.(b)Growthinsteam.3

48b

Figure1 .1. Comparisonof(a)diffusionand(b)ionimplantationt h i f th l ti i t d ti f d t i t thtechniquesfortheselectiveintroductionofdopants intothe

semiconductorsubstrate.

Figure 13 2 The schematic diagram of a typical open tube diffusionFigure1 .2. Theschematicdiagramofatypicalopentubediffusionsystem.

48c

Figure11.17. Solidsolubilities ofimpurityelementsinsilicon.11

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Figure14.5. Diffusionprofiles.(a)Normalizedcomplementaryerrorfunctionversusdistanceforsuccessivediffusiontimes.

(b) Normalized Gaussian function versus distance(b)NormalizedGaussianfunctionversusdistance.

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Figure14.11. Diffusioncontoursattheedgeofanoxidewindow,whererj istheradiusofcurvature.

14

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Figure14.12. Fourdifferentcasesofimpurityredistributionin silicon due to thermal oxidation.6insiliconduetothermaloxidation.

49c

Figure14.13. Schematicofamediumcurrentionimplantor.

Figure 1 14 (a) Schematic of the ion range R and projected rangeFigure14.14. (a)SchematicoftheionrangeR andprojectedrangep.(b)Twodimensionaldistributionoftheimplantedions.

16

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Figure14.25. Compositedopingprofileusingmultipleimplants.23

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Figure11.19. Threecommonsusceptors forchemicalvapordisposition:(a)horizontal,(b)pancake,and(c)barrelsusceptor.

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Figure3.1 Currentvo ltagecharacteristicsofatypicalsiliconpnjunction.

Figure3.2. (a)Uniformlydopedptypeandntypesemiconductorsbeforethejunctionisformed.(b)Theelectricfieldinthedepletion

i d th b d di f j ti i th lregionandtheenergybanddiagramofapn junctioninthermalequilibrium.

53b

Figure3.3. (a)Apn junctionwithabruptdopingchangesatthemetallurgicaljunction.(b)Energybanddiagramofanabruptjunctionatthermalequilibrium.(c)Spacechargedistribution.(d)Rectangular

i i f h h di ib iapproximationofthespacechargedistribution.

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Figure3.5. Approximatedopingprofiles.(a)Abruptjunction.(b)Linearlygradedjunction.

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Figure3.7. (a)Onesidedabruptjunction(withNA >>ND)inthermalequilibrium.(b)Spacechargedistribution.

(c)Electricfielddistribution.(d)Potentialdistributionwithdistance,whereVbi isthebuiltinpotential.

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Figure39. Linearlygradedjunctioninthermalequilibrium.(a)Impuritydistribution.(b)Electricfielddistribution.(c)

Potentialdistributionwithdistance.(d)Energybanddiagram.( ) gy g

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60a

Figure38. Schematicrepresentationofdepletionlayerwidthandenergybanddiagramsofapn junctionunder

variousbiasingconditions.a)Thermalequilbrium condition.(b)Forwardbiascondition.(c)Reversebiascondition.

60b

Figure314. Depletionregion,energybanddiagramandcarrierdistribution.(a)Forwardbias.(b)Reversebias.

60c

Figure315. Injectedminoritycarrierdistributionandelectronandholecurrents.(a)Forwardbias.(b)Reversebias.Thefigureillustratesidealizedcurrents.Forpracticaldevices,thecurrentsarenotconstantacrossthespacechargelayer.

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Figure317. ComparisonoftheforwardcurrentvoltagecharacteristicsofSiandGaAs diodes2 at300K.Dashedlines

indicateslopesofdifferentidealityfactors.p y

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Figure3.11. (a)pn junctionwithanarbitraryimpurityprofileunderreversebias.(b)Changeinspacechargedistributionduetochangeinappliedbias.(c)Correspondingchangein

electricfield distribution.electric fielddistribution.

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Figure3-22. Energybanddiagramsunderjunctionbreakdownconditions (a) Tunneling effect (b) Avalanche multiplicationconditions.(a)Tunnelingeffect(b)Avalanchemultiplication.

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Figure324. CriticalfieldatbreakdownversusbackgrounddopingforSiandGaAs onesidedabruptjunctions.5

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Figure3.25. Avalanchebreakdownvoltageversusimpurityconcentrationforonesidedabruptjunctionandavalancheb kd lt i it di t f li lbreakdownvoltageversusimpuritygradientforlinearly

gradedjunctioninSiandGaAs.Dashdotlineindicatestheonsetofthetunnelingmechanism.5

81b

Figure326. Breakdownvoltagefordiffusedjunctions.Insetshowsthespacechargedistribution.6

81c

Figure328. ( a)Planardiffusionprocessthatformsjunctioncurvatureneartheedgeofthediffusionmask,whererj isthe

radiusofcurvature.(b)Cylindricalandsphericalregionsformedbydiffusionthrougharectangularmask.

81d

Figure329. Breakdownvoltageversusimpurityconcentrationforonesidedabruptdopingprofilewith

cylindricalandsphericaljunctiongeometries,7 whererj isthey p j g , jradiusofcurvatureindicatedinFig.30.

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Figure3.20. Transientbehaviorofapn junction(a)Basicswitchingcircuit.(b)Transientresponseofthecurrentswitchedfromforward

bi t bibiastoreversebias.

Figure 4 23 Normalized transient time versus the ratio of forwardFigure321. Normalizedtransienttimeversustheratioofforwardcurrenttoreversecurrent.3

86b

Figure330. (a)Energybanddiagramoftwoisolatedsemiconductors.b)Energybanddiagramofanidealnp

heterojunction atthermalequilibrium.j q