fab well.pdf

7/28/2019 fab well.pdf

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CMOS LAB MANUAL

2011

Author:MatthewLeone

ToddKaiser

MontanaStateUniversity

Rev2 December2010CMO

SLA

BMA

NUAL

This manual was designed for use with the Montana Microfabrication

FacilityatMSU.TheintentionofthemanualistoprovidelabusersandMSU

students with a complete description of the methods used to fabricate

CMOSdeviceson4inchsiliconsubstrates.

SpecialThanksto:

AndyLingley

PhilHimmer


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SUPPLIERS

UniversityofMinnesotaNanoFabricationCenter(NFC):Photomaskswww.nfc.unm.edu

VirginiaSemiconductor:SiliconSubstrates

www.virginiasemi.com

ELCATInc.:SiliconSubstrates

www.elcat.com

JTBaker:ChemicalSupplies

www.mallbaker.com/default.asp

TechnicalGlassProductsInc:Quartzware

www.technicalglass.com

KurtJLeskerCompany:EvaporationFilaments

www.lesker.com

MSUChemstore:Labware/ChemicalSupplies

www.chemistry.montana.edu/chemstores

SigmaAldrich:ChemicalSupplies

www.sigmaaldrich.com

SPISupplies:WaferTweezers

http://www.2spi.com/spihome.html

GasesPlus:PressurizedGasTanks

www.gasesplus.com (406)3889109


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ThehightemperatureprocessstepsforuseinEE407labsthisyeararelistedhere.

wetoxidation 1000C 180min

Nwelldiffusion 825C 50minN2/25minO2

drivein 1000C 4hr/8hrW/&W/Ooxide


N+diffusion 850C 20min


P+diffusion 950C 20min

drivein 1000C 60min


dryoxidation 1000C 60min


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NOTES/RECOMMENDATIONSFROMTHEAUTHOR:

Previousfabricationattemptshavebeenmetwithmixedsuccess.Inmostcasesthelargechanneled

NMOStransistors,resistorsanddiodesfunctionedproperly.However,insomecasesthethresholdvoltagewas

negative,indicatingadepletionmodedeviceandperhapsinappropriatedopantlevels,butthediffusiontimesand

temperaturesshowednoassociation.Inmanycases,thesmallerchanneldevicesfailedtofunctionandexhibited

shortcircuitbehavior.

ThePMOSdevices,includingresistors,transistorsanddiodesnearlyalwaysfailed.Numerousreasons

werethoughttoexplainforthefailurebutnonehavebeenprovenasthecause.Themostobviousreasonfor

failuremayjustbeaninappropriatedopinglevelofeithertheNwellorP+devices.Thedopantconcentrations

mayhavebeenshiftedduetosegregationeffectsduringoxidegrowthorthermalcycles.Orthefailuremaybe

causedfrompoorelectricalcontacttothediffusedregions,perhapsathinfilmofBSGoroxidewasactingasa

barrierbetweenthealuminumanddiffusedsilicon.TypicallyafterBorondeposition,theresultingBSGfilmneeds

tobeetchedlongerthannecessarytoremovethermalSiO2. Ifinsufficientlyetched,theBorondopedregionswill

appearblueishandiftestedwiththeNanospecor4prointprobewillindicateoxideispresent.Thissituationhas

beenencounteredinpreviousfabricationattempts.

FrommyexperienceandreadingsIwouldrecommendtryingthefollowingmodifiedfabricationsequence.

Iftheprocesscannotbemadesuccessfulbymodifyingetchtimesordiffusionschedules,Iwouldrecommend

shiftingtheprocessfromanNwellonPtypesubstratetoaPwellonNtypesubstrate.Otheruniversitieshave

incorporatedthistypeofCMOSfabricationwithsuccessfulresults.

MatthewLeone

MontanaStateUniversity

2007

RecommendedCMOSProcess:Oxidation(wet): 1000C 90min

NwellPredeposition: 800C 20minOxidation(wet) 1050C 60min

NwellDrivein: 1050C 300min

N+S/DPredeposition: 850C 20min

Oxidation(wet): 1000C 60min

P+S/DPredeposition: 950C 20min

Oxidation(dry): 1050C 45min

LongOxideEtchin6:1BOEtoremoveBSGandSiO2fromvias.


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How to use this manual

14week Overview

Themanualisbrokenupintoweeklysegmentscontainingmultiplesections:Goals,Equipment,Parameters,

MethodsandResults.Eachweekasetofprocessgoalsispresentedtotheuseralongwithalistofequipmentand

themethodsusedtoachievethosegoals.Theparameterssegmentisdevotedtoprocessdependentparameters

specifictothefabricationmethodsusedthatweek.Theparametersarecolorcodedtocorrespondtoaspecific

processmethod.Themethodssectiondescribestheprocessesusedwithinthatweektoachievethedesiredgoals.

Themethodsarenumberedtocorrespondtoaprocessgoal.Theresultsectionisleftblankforuserstorecordthe

resultsofthatweeksprocesses.

Introduction&Oxidation Week1

Photolithography&Etching(Nwell) Week2

Cleaning&Diffusion(N) Week3

Documenting,Cleaning&Oxidation Week4

Photolithography&Etching(N+Source/Drain) Week5

Cleaning&Diffusion(N+) Week6


Photolithography&Etching(P+Source/Drain) Week8

Cleaning&Diffusion(P+) Week9


Photolithography&Etching(Vias) Week11

Cleaning&AluminumEvaporation Week12

Photolithography,Etching(Pads)&Documenting Week13

Probing&Testing Week14


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Introduction & Oxidation Week 1

OxidationParameters

Temperature(C) Time(minutes) Type(wetordry) N2/O2Flow BubblerSetting1000 180 Wet 7/9 40

EQUIPMENT:

WaferScribe JANDEL4pointProbeStation

RCAtanks(Optional) MODULABOxidationFurnace

GOALS:

1. Familiarize studentswith the cleanroomlayout,equipment,safetyandprocedure.

2.

Present

an

overview

of

the

MEMS

fabrication process and variousprocessing techniques (i.e.photolithography,etching,etc)

3. CharacterizethewafersubstratesandIDindividualwafers

4. RCAclean(Optionalfornewwafers)5. Oxidation(Fieldoxide)

PARAMETERS


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Methods:

1.CleanRoomEtiquette

Thelabemploysmanyhazardouschemicalsand

processes.Thesafetyofthelabstudentsandusersisthe

number one priority when participating in the lab.

Follow all gowning and safety procedures outlined by

thelabTA.Tomaintain the integrityofthewafersand the

equipment, adhere to the process descriptions and

detailsprovidedbythelabTA.

Themostcommonreasonawaferwillnotmake

it to the end of the fabrication sequence, is poor

handling.Thewafershouldbehandledwith thewafer

tweezersandwithgreatattention.Limitthehandlingof

the wafer with gloved hands to the edges and only

duringnecessarycircumstances.Never touch thewafer

with a bare hand and never touch the center of thewafer,evenwithglovedhands.

When processing in the cleanroom, sources of

contaminationareanotherfactorwhichmay inhibitthe

successofthefabrication.Therefore,donottalknextto

the wafers, keep the lid to the wafer box closed and

lastly,donothastilymoveaboutthecleanroomanddo

notgetinahurrytofinishaprocess.Whenalabstudent

getsinahurryitcreatesasituationwithagreaterlikely

hood of breaking a wafer or damaging a piece of

equipment.

Week1


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Methods:

2.ProcessOverview:

TheCMOSdevicesarefabricatedusingcommon

bulk silicon processing techniques. The sequence is a

simple set of repeating steps including oxidation,

etching,diffusion,cleaningandpatterning.Anoverview

of the sequence is shown to the right (Figure 1). Thefabrication portion of the lab should take roughly

thirteenweekstocomplete,withthefinalweekdevoted

totesting.

Alayoutofthedieisshowninthebottomright

(Figure2).Amore completedescriptionof thedevices

foundon thedie is foundat theendof thedocument

undertheDieLayoutsection.

Documenteverything seenanddone inaclean

room lab notebook. Record all measureable quantities

and procedures and any deviations. It is important torecord every detail which may help explain device

failuresoranomalies.

3.WaferCharacterizationandID:Semiconductorsubstrates,referredtoaswafers,

caneasilybeordered through retailersandcustomized

forspecificapplications.Thewafersusedforthelabare

100mmindiameter,52525mthick,,singleside

polished,single

crystal

silicon,

doped

with

boron

(Ptype)

toaresistivityof120 /cm.

Asimpletesttodetermine ifthesubstrate isP

typeorNtypesiliconisknownastheHotProbeTest.

Using a DMM and a soldering iron, heat the positive

probe of the DMM for several minutes with the

soldering iron. Make sure the DMM is set to measure

mV. Place both probe tips, positive and

negative(ground) to the wafer surface. If the DMM

indicatesapositivevoltagethesubstrateisNtype,ifthe

voltage is negative the substrate is Ptype. This testshouldbeaccurateuptoaresistivityof1000 /cm.

Week1Figure1Overviewofthefabricationsequence.

Figure 2 Microscope picture of the die layout. A more detaileddescriptionofthelayoutisfoundattheendofthisdocument.


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Methods:

3.WaferCharacterizationandID:

ContinuedThebulkresistivity(cm)isdeterminedbyfirst

acquiringthesheetresistivity (/) ofthewafersusing

theJANDEL 4pointProbe Stationand thenmultiplying

thisvaluebythewaferthicknessandacorrectionfactor.

SeetheJANDELmanual fordetailsonusingthe4point

probe.

Tokeep trackof individualwafers,a scribecan

be used to mark the back of the wafer with an

identificationmark,typicallyanumberorletter.

Proceedby lightlypressing the tipof thescribe

againstthesurfaceofthewaferandwithasfewstrokes

aspossiblescribeasectionnumberandwafernumber.

Scribingshouldbedoneasclosetotheedgeaspossible

tolimittheeffectonfabricateddevices.

5.Oxidation:GrowingSiO2

(CheckParameterssectionfordetails)

The goal of the first oxidation run is to grow

enoughsilicondioxide(SiO2)roughlya0.5mthickfilm,

tomaskthesubsequentdiffusion.

Tooxidize,insertthewafers intotheMODULAB

oxidationfurnaceusing thequartz rodandquartzboat

(seeFigure4).Thereshouldbetwodummywafers,oneat the front of the boat and another at the rear, to

maintainuniformityacross theboat.Ramp the furnace

to 600C before the removing the quartz boat and

loading the wafers. Prior to the temperature reaching

400C, turnon thenitrogen topurge the furnace.Also,

set the potentiometer on the bubbler if performing a

wet oxidation (which we are). Once the wafers are

loadedand inplaceat thecenterof the furnace, ramp

the furnace to the desired temperature. When the

desiredtemperatureisreachedstartthetimer,stopthenitrogenflowandturnontheoxygen.Aftertheallotted

time, ramp the furnace down to 600C, pull the boat,

remove thewafers,and set themaside to cool.When

finished, turn the furnace to 0C and turn off the

nitrogenwhenthetemperaturedropsbelow400C.

Week1Figure3Scribingthesurfaceofawaferusingasteeltippedscribe.

Figure 4 A student using a quartz rod to insert wafers into theoxidationfurnace.


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SheetResistance(/)&Resistivity(cm):

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NOTES/CHANGES:

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RESULTS: Week1


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Photolithography & Etching (Nwell) Week 2

EQUIPMENT:

Nanospec

BREWERspincoaterandhotplate

SHIPLEY1813positivephotoresist ABMContactMaskAligner

MF319developer

TeflonCassette

6:1BOE

GOALS:

1. Measure the thickness of the SiO2 withtheNanospec.

2.

Photolithography(Mask

#1

Nwell)

3. Hardbake4. EtchSiO2

PARAMETERS:

Spincoat&SoftbakeParameters

SpinProgram

Speed(RPM)

Time(seconds)

Ramp(RPM/s)

DispenseType

(automaticormanual)

SoftbakeProgram

Temperature(C)

Time(minutes)

#9 5250 30 20000 Manual(static)

#2 115 2

Exposure&DevelopmentParameters(MASK#1)

MaskOrientation(writingtoward

orawayfromuser)

WaferOrientation(flattotheleftorthe

right)

UVIntensityChannelB(mW/cm2)

UVDose(J/cm2)

ExposureTime(seconds)

DevelopmentTime(seconds)

Away Left 30 ~135 4.5 3060HardbakeParameters

HardbakeProgram Temperature(C) Time(minutes)#2 115 2

SiO2EtchParameters*for4,2004,500 thickSiO2layer

BOEconcentration SiO2EtchRate(/min) Approx.EtchTime(minutes) EtchMask6:1 900 5* Shipley1813Photoresist


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Methods:

1.MeasuringtheSiO2thickness:

The thickness of the freshly grown silicon

dioxide layer is measured with the Nanospec. Choose

theappropriatefilmtypeduringthepromptsandusea

blank wafer as reference. Measure the thickness at

several different points on the wafer to monitoruniformity and determine a maximum film thickness.

AlsonotethatthethicknessoftheSiO2determinesthe

color of the wafer, therefore, color can be used to

approximate film thicknessesand identifyanomalies in

film.Forreference,theNanospecpromptsformeasuring

SiO2thicknessare:

Iswavelength480nm? Y (ifnot,typeNandvalue)

Databankoption? N

Refrindexoption? N

Switchtoprinter? N

Enterfilmtype: 1SiO2

Enterobjlens: 1=10x

2.PhotolithographywithMask#1(Nwell):

Spincoating&Softbaking


The goal of the photolithography step is to

transfer patterns from the mask set to the wafer

surface.Photoresist,whichisaUVsensitivechemical,is

patterned by selectively exposing certain regions with

UV light. Photoresist isalso chemically resistant to the

SiO2etchant,hydrofluoricacid(alsoreferredtoasBOE);

therefore itisusedtomask,orblock,selectportionsof

the SiO2 from being etched. The first patterns

transferred to thewaferaretheNwells,whichwillact

asasubstrateforthePMOSdevices.

Beginby

using

the

BREWER

spin

coater

tospin

a

thin film (~1um) ofSHIPLEY1813photoresistonto the

topside of the wafer. Next, transfer the wafer to the

adjacenthotplateandsoftbaketoremovesolventsand

hardenthe resist.Agoodcoatingofphotoresistwillbe

barely visible to the naked eye and have a minimal

numberofstreaksorblotches(seeFigure7).Ifthereare

alargenumberofdefects,solventclean,dehydrate,and

tryrespinningmorephotoresist.

Week2Figure5StudentsusingtheNanospectomeasuretheSiO2thickness.

Figure6ViewfromtheNanospeceyepiece,theedgeoftheoctagonshouldbeinfocusforpropermeasurement.

Figure 7 Wafers that have been spun with photoresist and exhibitsignsofapoorcoatingi.e.streaking,blotchinessandcolorgradients


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Methods:

2.PhotolithographywithMask#1(Nwell):

Exposure&Development(CheckParameterssectionfordetails)

Proceed by patterning the photoresist with

Mask #1. Start by loading the mask onto the ABM

contactaligner mask stage. Turn the maskvac on andraisethemaskstage.Carefully, loadthewaferontothe

substratechuckandorient itsuchthattheplane

(wafer flat) is to the left and running straight up and

down. Turn on the substratevac to lock the wafer in

placeand lower the chuck toavoidhitting the contact

mask. Next, lower the mask stage and raise the

substrate chuck up to meet the mask, fringe lines will

become visible as the wafer and mask come into

contact.Alignthemaskto thewaferusing themarkers

on the sides of the wafer (no alignment for the first

photolithography step). Turn on the contactvac to

removeanyairgapbetweenmaskandwafer.Adjustthe

exposuretimeandchannelsettingthenexpose.Remove

the wafer by turning off the contactvac, lowering the

substratechuck,raisingthemaskframe,andturningoff

thesubstratevac.TransferthewafertoadishofMF319

developer(afaintoutlineofthefeaturescanbeseenat

this point), submerge the wafer in MF319 and gently

swirl for 3060 seconds until the exposed resist is

completelydissolved. Ifdonecorrectly there shouldbe

nophotoresist left inthenwellregions. Ifthere is (see

Figure8),resubmergethewaferintheMF319developer

foradditional time. Ifunsuccessful,usea solvent clean

to strip the photoresist, dehydrate and respin again.

When finished, pour the used MF319 into the MF319

wastecontainerlocatedunderthesolventbenchnextto

thephotoresist.

Week2

3.Hardbaking:


Hardbaking is the final step in the

photolithography sequence, but to emphasize its

importanceitgetsitsownheading.Thegoalofthehard

bake istoremoveanyremainingsolventsand/orwaterfromtheresist.Ithasbeenobserved,thatwithouthard

baking, thephotoresistexhibitsadhesionproblemsand

frequentlydelaminatesfromthesurfaceduringetching.

Hardbakingisverysimilartosoftbakingandfollowsthe

sameprocedure.Loadawaferontoahotplateforaset

timeattheappropriatetemperature.

Figure 8 A microscope picture of a patterned feature afterdevelopment in MF319. The color gradient indicates that thephotoresist was not completely removed during the development.

Thewafer shouldbedeveloped for longeror redonewitha longerexposure.

Figure 9 Several features indicating photoresist adhesionproblemsafteretchingSiO2.ThecolorgradientshowsataperedSiO2etchafterthephotoresistdelaminated.


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Methods:

4.EtchingtheSiO2:

(CheckParameterssectionfordetails)ThegoaloftheSiO2etchistoremovethesilicon

dioxide from the exposed regions in the photoresist.

SilicondioxideisetchedwithBOE(BufferedOxideEtch)

which is a combination of hydrofluoric acid andbuffering chemicals to stabilize the reaction. BOE is

highlyselectivetosilicondioxidesothephotoresistwill

notbeetched.

ThisstepshouldbecarriedoutbythelabTAfor

safetyreasons.BeginbyloadingthewafersintoaTeflon

cassettewithequal spacingbetweenwafers.Using the

handle, submerge the cassette in 6:1 BOE for the

appropriateamountoftimeoruntiltheexposedSiO2is

completely removed. To determine if the SiO2 is

completely removed, check the regions for color (see

Figure 10) and hydrophobicity. When the etch is

complete,removethecassetteandrinsethewafersina

bucket of DI water. Pull the cassette from the rinse

bucketandrinseanddryindividualwaferswithDIwater

andnitrogengun.

Figure 10 An example of micromasking with features that wereetchedbuthadundevelopedphotoresistmaskingtheetch.Thebluecolor indicatesthatSiO2stillremainsoverthosefeatures.Thewhitecolor is bare silicon. Micromasking can usually be solved with adescumetch(dryO2plasmaetch)beforeetchinginBOE.

Week2Figure11AprofilometermeasurementinreferencetoFigure10.Thedataindicatesthatasmallamount(250nm)ofSiO2remainsinetchedwindows.ThisSiO2willinhibitthefollowingdiffusion.


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RESULTS: Week2

SiO2Thickness( ):

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NOTES/CHANGES:

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Cleaning & Diffusion (N) Week 3

EQUIPMENT:

Acetone,Methanol,Isopropyl

MODULABPhosphorousDiffusion

Furnace PHOSPLUSTP250PhosphorousSources

RCACleanTanks

PARAMETERS:

RCACleanParameters

PiranhaSolution PiranhaEtchTime(minutes)

BOEsolution BOEEtchTime(seconds)

IonicClean IonicCleanEtchTime

(minutes)3:1

H2O2:H2SO4

10 6:1 10 6:1:1H2O:H2O2:HCl

10

PhosphorousDiffusionParameters(Nwell)

BoronSource Temperature(C) Time(minutes) N2FlowPHOSPLUSTP250 900 20 7

DriveinParameters(Nwell)

BoronSource Temperature(C) Time(minutes) N2FlowNone 1000 600 7

GOALS:

1. FullWaferClean(Solvent&RCA)2. PhosphorusDiffusion


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Methods:

1.WaferCleaning:

(CheckParameterssectionfordetails)The wafers need to be cleaned to remove

photoresist,andanypossible sourcesofcontamination

beforebeingplacedinahightemperaturefurnace.

To remove the photoresist a solvent clean isperformed.Beginbyplacinganevaporatingdishonthe

solventbench to catch solvent waste. Rinse the wafer

with acetone using the squirt bottle, and follow with

methanol and isopropyl. The acetone will remove the

photoresist and the methanol and isopropyl with

remove any acetone residue. Rinse the wafers in DI

wateranddrywithanitrogengun.Whenfinishedpour

thesolventwasteintotheSolventWasteContainer.

To removepossible sourcesofcontaminationa

modifiedRCAcleanisperformed.TheRCAcleanconsists

of rinsing the wafers in three chemical solutions. The

first isamixtureofsulfuricacidandhydrogenperoxide

known as Piranha etch. The piranha etch will remove

any organic material. The second mixture is a simple

BOE solutionwhichwill stripanynativeoxide thathas

accumulated on the wafer surface. The third and final

solutionisdesignedtoremoveanyheavymetalions,itis

a mixture of hydrochloric acid, water and hydrogen

peroxide.Thissolutionisreferredtoasionicclean

This step shouldalsobe carriedoutby the lab

TA. Load thewafers intoaTeflon cassette transfer the

cassettebetweentheRCAsolutionsuntilthecleaningis

complete.Rinse thewafersandcassette inabucketof

DIwaterthenpulleachwaferandrinseanddrybyhand.

Figure 12 Wafers submerged in Piranha Etch to remove organiccontaminates.

Week3

6.PhosphorousDiffusion:


Thegoalof thephosphorousdiffusion is to flip

the polarity of the Ptype substrate in the Nwells. In

other words, the diffusion will create Ntype silicon

areasonthewafer.TheseNwellsorTUBSwillactasthesubstrateforthePMOSdevices.

The diffusion is modeled as a solidsolubility

limiteddiffusion followedbyseveraldriveinsteps.The

expectedresistivitycanbederivedfromthismodeland

verifiedwiththePHOSPLUSdatasheet.

TodiffuseNtype (Phosphorous)material,ramp

theMODULABPhosphorousDiffusion Furnace to600C

andsetthenitrogenflow.Removethequartzboatwith

the solid, white, PHOSPLUS TP250 sources already in

place. Load the siliconwafersnext to the sourceswith

thepatternedsidefacingasource(seeFigureB). Insert

thequartzboat to the centerof the furnaceand ramp

the furnace to the desired temperature. When the

desiredtemperatureisreachedstartthetimer.Afterthe

allottedtime,rampthefurnacedownto600C,pullthe

quartzboatandremovethewafersandsetthemaside

tocool.Whenfinished,turnthefurnaceto0Candturn

off the nitrogen when the temperature drops below

400C.

FigureBAnillustrationofhowthewafersareloadedintothequartz

boatnexttothediffusionsources.


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RESULTS: Week3

RESULTS:

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NOTES/CHANGES:

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Documenting, Cleaning & Oxidation Week 4

EQUIPMENT:

OpticalMicroscope 6:1BOE

Tefloncassette JANDEL4pointProbeStation RCACleantanks MODULABOxidationFurnace CANONDigitalCamera

PARAMETERS:

GOALS:

1. Take pictures using the microscope anddigitalcamera.

2.

Stripthe

SiO2

&PSG

3. Obtain 4point probe measurements ofthediffusion

4. RCAclean5. Oxidation


BOEconcentration SiO2EtchRate(/min) Approx.EtchTime(minutes) EtchMask6:1 900 5* none

RCACleanParameters




(minutes)3:1

H2O2:H2SO4

10 6:1 10 6:1:1

H2O:H2O2:HCl

10

OxidationParameters



20/64

Methods:

1.TakingPictures:

With the first diffusion completed, the wafers

nowhaveobservablefeatures.Fromthispoint,onegoal

of the lab is to document the fabrication progress by

takingpicturesof the surfaceof thewaferas itmoves

through the sequence. Begin by using the opticalmicroscopeandCANONdigitalcameratotakeapicture

ofthediffusedNwell(showninFigure13)

Figure13AdiffusedNwell.Theaddeddopantscreatethedifferentcolor.

4.StrippingtheSiO2andPSG:

(CheckParameterssectionfordetails)Preparethewafersurfaceforthenextoxidation

bycompletelyremovingalltheSiO2andPSG.

REPEAT:This step shouldbe carriedoutby the

lab TA for safety reasons.Beginby loading the wafers

into a Teflon cassette with equal spacing between

wafers.Using thehandle, submerge thecassette in6:1

BOE for the appropriate amount of time or until the

exposedSiO2iscompletelyremoved.Todetermineifthe

SiO2 iscompletely removed,checkthe regions forcolor

(see Figure 9) and hydrophobicity. When the etch iscomplete,removethecassetteandrinsethewafersina



andnitrogengun.

Week4Figure 14 A lab TA handling acids at the rinse sink with full acidprotectionclothing.Notethefacemask,apron,andchemicalgloves.

3.DiffusionMeasurements:

There is a large diffused rectangle/square test

region. This region is used to measure the sheet

resistivity associated with the phosphorus Nwell

diffusion (seeFigure16nextpage).Use theJANDEL4

point probe to measure the sheet resistivity of the

diffusion.Startbyraisingtheprobearm,uncappingthe

tipandplacingthewaferonthestage.Aligntheprobes

over the test region and lower the arm into contact.

Start the testbyusinga small current, roughly100nA,and increment the current until the sheet resistivity

stabilizes.ConsulttheJANDEL4pointprobemanualfor

furtherassistance.Themeasuredsheetresistivityshould

correspond to the value foundon this PHOSPLUS data

sheet for the appropriate time and temperature (see

Figure17nextpage).

Figure15AstudentusingtheJANDEL4pointprobetodocumentthesheetresistivityofthediffusion.


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Methods:Figure16Anoutlineofthewaferdiffusiontestregions.Thearea inpinkisdiffusedasN andshouldbetestedwiththe4pointprobe.

Figure 17 A graph from the PhosPlus datasheet illustrating therelationship between diffusion time, temperature and sheetresistivity. The graph should be used to verify sheetresistivitymeasurements.

Week4

4.RCACleaning:

(CheckParameterssectionfordetails)REPEAT: To remove possible sources of

contaminationamodifiedRCA clean isperformed.The

RCA clean consists of rinsing the wafers in three

chemicalsolutions:Piranhaetch,BOE,Ionicclean.ThisstepshouldbecarriedoutbythelabTAfor

safety. Load the wafers into a Teflon cassette transfer

the cassette between the RCA solutions until the

cleaning iscomplete.Rinsethewafersandcassette ina

bucketofDIwater thenpulleachwaferand rinseand

drybyhand.


(CheckParameterssectionfordetails)Thegoalofthesecondoxidationrunisthesame

asthefirst:growenoughsilicondioxide(SiO2)roughlya

0.5mthickfilm,tomaskthesubsequentdiffusion.

REPEAT: To oxidize, insert the wafers into the

MODULAB oxidationfurnace using the quartz rod and

quartzboat(seeFigure4).Thereshouldbetwodummy

wafers,oneatthefrontoftheboatandanotheratthe

rear, tomaintainuniformityacross theboat.Ramp the

furnace to 600Cbefore the removing thequartzboat

and loading the wafers. Prior to the temperaturereaching 400C, turn on the nitrogen to purge the

furnace.Also, set the potentiometer on the bubbler if

performing a wet oxidation (which we are). Once the

wafers are loaded and in place at the center of the

furnace, ramp the furnace to thedesired temperature.

When the desired temperature is reached start the

timer, stop the nitrogen flow and turnon theoxygen.

Aftertheallottedtime,rampthefurnacedownto600C

(or0C if finishedwith furnace),pull theboat, remove

the wafers, and set them aside to cool. When thetemperature drops below 400C the nitrogen can be

turnedoff.


22/64


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______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

NOTES/CHANGES:

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

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___________________________________________________________________________

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RESULTS: Week4


23/64

Photolitho & Etching(N+ Source/Drain) Week 5

EQUIPMENT:

Nanospec

BREWERspincoaterandhotplate

SHIPLEY1813positivephotoresist ABMContactMaskAligner

MF319developer

TeflonCassette

6:1BOE

PARAMETERS:


SpinProgram

Speed(RPM)

Time(seconds)

Ramp(RPM/s)

DispenseType

(automaticormanual)

SoftbakeProgram

Temperature(C)

Time(minutes)

#9 5250 30 20000 Manual(static)

#2 115 2



orawayfromuser)


right)


UVDose(J/cm2)



Away Left 30 ~135 4.5 3060HardbakeParameters

HardbakeProgram Temperature(C) Time(minutes)#2 115 2



GOALS:

1. Measure the thickness of the SiO2 layerwiththeNanospec.

2.

Photolithography

(Mask#2N+Source/Drain)3. Hardbake4. EtchSiO2


24/64

Methods:


Measure the thicknessof the silicondioxideat

several different points on the wafer using the

Nanospec. For reference, the Nanospec prompts for

measuringSiO2thicknessare:


Databankoption? N

Refrindexoption? N

Switchtoprinter? N


Enterobjlens: 1=10x

2.PhotolithographywithMask#2(N+S/D):

Spincoating

&

Soft

baking


The second mask contains the features for the

NMOSsourcesanddrains.

REPEAT:BeginbyusingtheBREWERspincoater

tospinathinfilmofSHIPLEY1813photoresistontothe








Figure18StudentsandprofessorlookingonasawaferisalignedandexposedattheABMcontactaligner.

Week5

2.PhotolithographywithMask#2(N+S/D):



Mask#2.

REPEAT:Load themaskonto theABM contactalignermaskstage.Turn themaskvaconandraisethe

maskstage.Carefully,loadthewaferontothesubstrate

chuckandorientitsuchthattheplane(waferflat)

istotheleftandrunningstraightupanddown.Turnon

the substratevac to lock thewafer inplaceand lower

thechucktoavoidhittingthecontactmask.Next,lower

themaskstageandraisethesubstratechuckuptomeet

themask, fringe lineswillbecome visible as thewafer

andmaskcomeintocontact.Alignthemasktothewafer

usingthemarkersonthesidesofthewafer.Turnonthe

contactvac to remove any air gap between mask and

wafer. Adjust the exposure time and channel setting

then expose. Remove the wafer by turning off the

contactvac, lowering the substrate chuck, raising the

mask frame,andturningoffthesubstratevac.Transfer

thewafer toadishofMF319developer (a faintoutline

ofthefeaturescanbeseenatthispoint),submergethe

waferinMF319andgentlyswirlfor3060secondsuntil

the exposed resist is completely dissolved. If done

correctly there should be no photoresist left in the

diffusion contact regions (see Figure 8). If there is,

resubmerge the wafer in the MF319 developer for

additional time. If unsuccessful, use a solvent clean to

strip the photoresist, dehydrate and respin again.



thephotoresist.


25/64

Methods:

3.Hardbaking:


REPEAT: It has been observed, that without

hardbaking,thephotoresistexhibitsadhesionproblems

and frequently delaminates from the surface during

etching. Hardbaking is very similar to softbaking andfollows the same procedure. Load a wafer onto a

hotplateforasettimeattheappropriatetemperature.

4.EtchingtheSiO2:

(CheckParameterssectionfordetails)REPEAT:This step shouldbe carriedoutby the



wafers.Using thehandle, submerge thecassette in6:1BOE for the appropriate amount of time or until the



(see Figure 9) and hydrophobicity. When the etch is




andnitrogengun.

Week5


26/64

SiO2Thickness( ):

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

NOTES/CHANGES:

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

RESULTS: Week5


27/64

Cleaning & Diffusion (N+) Week 6

EQUIPMENT:

RCATanks

Acetone,Methanol,Isopropyl

PhosphorousDiffusionFurnace PHOSPLUSTP250PhosphorousSources

TeflonCassette

PARAMETERS:

RCACleanParameters




(minutes)3:1

H2O2:H2SO4

10 6:1 10 6:1:1H2O:H2O2:HCl

10

BoronDiffusionParameters(N+)

BoronSource Temperature(C) Time(minutes) N2Flow

PHOSPLUSTP250 900 60 7

GOALS:

1. FullWaferClean(Solvent&RCA)2. PhosphorousDiffusion


28/64

Methods:

1.WaferCleaning:




REPEAT: To remove the photoresist a solventcleanisperformed.Beginbyplacinganevaporatingdish

on the solventbench tocatch solventwaste.Rinse the

wafer with acetone using the squirt bottle, and follow

withmethanol and isopropyl. The acetonewill remove

the photoresist and the methanol and isopropyl with




REPEAT: To remove possible sources of

contaminationamodifiedRCA clean isperformed.This

stepshouldbecarriedoutbythelabTA.Loadthewafers

intoaTefloncassettetransferthecassettebetweenthe

RCA solutionsuntil the cleaning is complete.Rinse the

wafers and cassette in a bucket of DI water then pull

eachwaferandrinseanddrybyhand,

6.PhosphorousDiffusion:


The goal of the phosphorous diffusion is tocreatehighlydopedNtypesilicontoactasthesources

anddrainsoftheNMOStransistors.

REPEAT: To diffuse Ntype (Phosphorous)

material, ramp the MODULAB Phosphorous Diffusion

Furnaceto600Candsetthenitrogenflow.Removethe

quartz boat with the solid, white, PHOSPLUS TP250

sourcesalreadyinplace.Loadthesiliconwafersnextto

the sources with the patterned side facing a source.

Insert thequartzboat to thecenterof the furnaceand

rampthefurnacetothedesiredtemperature.Whenthedesiredtemperatureisreachedstartthetimer.Afterthe

allottedtime,rampthefurnacedownto600C(or0Cif

finishedwithfurnace),pullthequartzboatandremove

the wafers and set them aside to cool. When the

temperature drops below 400C the nitrogen can be

turnedoff.

Week6


29/64

RESULTS:

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

NOTES/CHANGES:

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

RESULTS: Week6


30/64


PARAMETERS:


BOEconcentration SiO2EtchRate(/min) Approx.EtchTime(minutes) EtchMask

6:1 900 5* noneRCACleanParameters




(minutes)3:1

H2O2:H2SO4

10 6:1 10 6:1:1H2O:H2O2:HCl

10

OxidationParameters


GOALS:

1. Take pictures using the microscope anddigitalcamera

2.

Stripthe

SiO2

and

PSG

3. Obtain 4point probe measurements ofthediffusion

4. RCAclean5. Oxidation

EQUIPMENT:

OpticalMicroscope CANONDigitalCamera

6:1BOE TeflonCassette JANDEL4pointProbeStation RCATanks MODULABOxidationFurnace


31/64

Methods:

1.TakingPictures:

Use theOpticalMicroscopeandCANONDigital

Camera to takepicturesof thediffusedNMOS sources

anddrains.

Figure19DiffusedNMOSsourcesanddrains.

2.StrippingtheSiO2andPSG:














andnitrogengun.

Week7


Use theJANDEL 4pointprobe to measure the

sheetresistivityoftheN+andNwelldiffusions(Referto

Figure21forthelocationofthediffusedareas).Consult

theJANDEL4pointprobemanualforfurtherassistance.

Themeasured sheet resistivityof theN+ region shouldcorrespond to the value found on the PhosPlus data

sheet(seeFigure20).

Figure 20 A graph from the PhosPlus datasheet illustrating therelationship between diffusion time, temperature and sheetresistivity.

Figure21Anoutlineofthewaferdiffusiontestregions.Thearea inpinkisthefreshlydiffusedN+regionandshouldbetestedwiththe4pointprobe.


32/64

Week7



Thegoaloftheoxidationrunistogrowenough

silicondioxide(SiO2)roughlya0.5mthickfilm,tomask

thesubsequentdiffusion.

REPEAT: To oxidize, insert the wafers into theMODULAB oxidationfurnace using the quartz rod and

quartzboat(seeFigure4).Thereshouldbetwodummy

wafers,oneatthefrontoftheboatandanotheratthe

rear, tomaintainuniformityacross theboat.Ramp the

furnace to 600Cbefore the removing thequartzboat

and loading the wafers. Prior to the temperature

reaching 400C, turn on the nitrogen to purge the

furnace.Also, set the potentiometer on the bubbler if

performing a wet oxidation (which we are). Once the

wafers are loaded and in place at the center of the

furnace, ramp the furnace to thedesired temperature.

When the desired temperature is reached start the

timer, stop the nitrogen flow and turnon theoxygen.

Aftertheallottedtime,rampthefurnacedownto600C

(or0C if finishedwith furnace),pull theboat, remove

the wafers, and set them aside to cool. When the

temperature drops below 400C the nitrogen can be

turnedoff.

Methods:

4.RCACleaning:




chemicalsolutions:Piranhaetch,BOE,Ionicclean.ThisstepshouldbecarriedoutbythelabTAfor



cleaningiscomplete.Rinsethewafersandcassette ina


drybyhand.


33/64


___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

NOTES/CHANGES:

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

RESULTS: Week7


34/64

Photolitho & Etching (P+ Source/Drain) Week 8

PARAMETERS:


Spin

Program

Speed

(RPM)

Time

(seconds)

Ramp

(RPM/s)

Dispense

Type(automaticor

manual)

Softbake

Program

Temperature

(C)

Time

(minutes)

#9 5250 30 20000 Manual(static)

#2 115 2



orawayfromuser)


right)


UVDose(J/cm2)



Away Left 30 ~135 4.5 3060

HardbakeParametersHardbakeProgram Temperature(C) Time(minutes)

#2 115 2SiO2EtchParameters*for4,2004,500 thickSiO2layer


EQUIPMENT:

Nanospec BREWERspincoaterandhotplate

SHIPLEY1813positivephotoresist ABMContactMaskAligner MF319developer 6:1BOE TeflonCassette

GOALS:

1. Measure the thickness of the SiO2 layerwiththeNanospec

2.

Photolithography

(Mask#3P+Source/Drain)3. Hardbake4. SiO2Etch


35/64

Methods:







Databankoption? N

Refrindexoption? N

Switchtoprinter? N


Enterobjlens: 1=10x

2.PhotolithographywithMask#3(P+S/D):

Spincoating

&

Soft

baking


The third mask contains the features for the

PMOSsourcesanddrains.










Figure22AstudentusingtheABMmaskalignertoalignMask#3.

Week8

2.PhotolithographywithMask#3(P+S/D):



Mask#3.



























thephotoresist.


36/64

Methods:

3.Hardbaking:







4.EtchingtheSiO2:











andnitrogengun.

Week8


37/64

SiO2Thickness( ):

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

NOTES/CHANGES:

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

RESULTS: Week8


38/64

Cleaning & Diffusion (P+) Week 9

PARAMETERS:

RCACleanParameters




(minutes)3:1

H2O2:H2SO4

10 6:1 10 6:1:1

H2O:H2O2:HCl

10

BoronDiffusionParameters(DIFFUSEDCONTACTS)

BoronSource Temperature(C) Time(minutes) N2FlowBORONPLUSGS139 1000 120 7

DriveinParameters(DIFFUSEDCONTACTS)

BoronSource Temperature(C) Time(minutes) N2Flownone 1000 60 7

EQUIPMENT:

Acetone,Methanol,Isopropyl RCATanks

BoronDiffusionFurnace BORONPLUSGS139BoronSources

GOALS:

1. FullWaferClean(Solvent&RCA)2. BoronDiffusion


39/64

Methods:

1.WaferCleaning:




REPEAT: To remove the photoresist a solventcleanisperformed.Beginbyplacinganevaporatingdish

on the solventbench tocatch solventwaste.Rinse the

wafer with acetone using the squirt bottle, and follow

withmethanol and isopropyl. The acetonewill remove

the photoresist and the methanol and isopropyl with




REPEAT: To remove possible sources of

contaminationamodifiedRCA clean isperformed.This

stepshouldbecarriedoutbythelabTA.Loadthewafers

intoaTefloncassettetransferthecassettebetweenthe

RCA solutionsuntil the cleaning is complete.Rinse the

wafers and cassette in a bucket of DI water then pull

eachwaferandrinseanddrybyhand,

6.BoronDiffusion:


The goal of the boron diffusion is to createhighly doped Ptype silicon to act as the sources and

drainsofthePMOStransistors.

REPEAT: To diffuse Ptype (Boron) material,

ramptheLindbergBlueBoronDiffusionFurnaceto600C

andsetthenitrogenflow.Removethequartzboatwith

thesolid,white,BORONPLUSGS139sourcesalready in

place. Load the siliconwafersnext to the sourceswith

thepatternedsidefacingasource.Insertthequartzboat

tothecenterofthefurnaceandrampthefurnacetothe

desired temperature.When thedesired temperature isreached start the timer. After the allotted time, ramp

the furnace down to 600C (or 0C if finished with

furnace), pull the quartz boat and remove the wafers

and set them aside to cool. When the temperature

dropsbelow400Cthenitrogencanbeturnedoff.

Week9


40/64

RESULTS:

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

NOTES/CHANGES:

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

RESULTS: Week9


41/64


PARAMETERS:



RCACleanParameters




(minutes)

3:1H2O2:H2SO4

10 6:1 10 6:1:1H2O:H2O2:HCl

10

OxidationParameters

Temperature(C) Time(minutes) Type(wetordry) N2/O2Flow BubblerSetting1000 30 Wet 7/9 N/A

OxidationParameters

Temperature(C) Time(minutes) Type(wetordry) N2/O2Flow BubblerSetting1000 60 Dry 7/9 N/A

EQUIPMENT:

OpticalMicroscope CANONDigitalCamera

JANDEL4pointprobe RCAtanks MODULABOxidationFurnace

GOALS:

1. Take pictures with microscope andcamera

2.

StripSiO2 and

BSG

3. 4pointprobe3. RCAclean4. DryOxidation


42/64

Methods:

1.TakingPictures:


Camera to takepicturesof thediffused PMOS sources

anddrains.

Figure23DiffusedPMOSandNMOSsourcesanddrains.

2.Stripping

the

SiO2

and

PSG:









SiO2 iscompletely removed,checkthe regions forcolor(see Figure 9) and hydrophobicity. When the etch is




andnitrogengun.

Week10


Use the 4point probe to measure the sheet

resistivityof theP+,N+andNwelldiffusions (Refer to

Figure25forthelocationofthediffusedareas).Consult

theJANDEL4pointprobemanualforfurtherassistance.

Themeasured sheet resistivityof theP+ region shouldcorrespond to the value found on the BoronPlus data

sheet(seeFigure24).

Figure24GraphfromtheBoronPlusdatasheet.


43/64

Methods:

1.TakingPictures:


Camera to takepicturesof thediffused PMOS sources

anddrains.

Figure16CompletedType2piezoresistors.

2.Stripping

the

SiO2

and

PSG:









SiO2 iscompletely removed,checkthe regions forcolor(see Figure 9) and hydrophobicity. When the etch is




andnitrogengun.

Week10

5.DryOxidation:GrowingSiO2


Thegoalof the fourthoxidation run is togrow

the gate oxide. The oxide thickness should be

approximately 700 thick. The method of oxidation

differs from theprevious runs, theoxidewillbegrownwithdryO2.

REPEAT: To oxidize, insert the wafers into

oxidationfurnaceusingthequartzrodandquartzboat.

Thereshouldbetwodummywafers,oneatthefrontof

theboatandanotherattherear,tomaintainuniformity

acrosstheboat.Ramp the furnace to600Cbefore the

removing thequartzboatand loading thewafers.Prior

tothetemperaturereaching400C,turnonthenitrogen

to purge the furnace. Load the wafers and insert the

quartzboat to thecenterof the furnaceand ramp the

furnace to thedesired temperature.When thedesired

temperature is reached start the timer, stop the

nitrogenflowandturnontheoxygen.Aftertheallotted

time,rampthefurnacedownto600C(or0Ciffinished

withfurnace),pulltheboat,removethewafers,andset

themasidetocool.

Methods:Figure25Anoutlineofthewaferdiffusiontestregions.Thearea inpink is diffused as P+. Test each area with the 4point probe andrecordthefinalsheetresistivities.

4.RCACleaning:




chemicalsolutions:Piranhaetch,BOE,Ionicclean.

ThisstepshouldbecarriedoutbythelabTAfor



cleaningiscomplete.Rinsethewafersandcassette ina


drybyhand.


44/64


___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

NOTES/CHANGES: Ashortwetoxidationwasaddedalongwithanothermaskingstep.

Thegateoxidemask(GOX)removesthefieldoxidewherethegateoxideistobegrown

andgeneratesthealignmentmarksforthecontactmask. Inthepastthisstepwas

removedtoexpeditetheprocesssothatitcouldbefinishedbytheendoftheterm.WenowstartonWeek#2withthesubstratesalreadyoxidizedtoallowfortheextra

processingstepsnow.

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

RESULTS: Week10


45/64

Photolithography & Etching (Vias) Week 11

PARAMETERS:


Spin

Program

Speed

(RPM)

Time

(seconds)

Ramp

(RPM/s)

Dispense

Type(automaticor

manual)

Softbake

Program

Temperature

(C)

Time

(minutes)

#9 5250 30 20000 Manual(static)

#2 115 2



orawayfromuser)


right)


UVDose(J/cm2)



Away Left 30 ~135 4.5 3060

HardbakeParametersHardbakeProgram Temperature(C) Time(minutes)

#2 115 2SiO2EtchParameters*for4,2004,500 thickSiO2layer


EQUIPMENT:

Nanospec BREWERspincoaterandhotplate

SHIPLEY1813positivephotoresist ABMContactMaskAligner MF319developer 6:1BOE TeflonCassette

GOALS:

1. Measure the thickness of the SiO2 layerwiththeNanospec

2.

Photolithography(Mask

#4

Vias)

3. Hardbake4. SiO2Etch


46/64

Methods:







Databankoption? N

Refrindexoption? N

Switchtoprinter? N


Enterobjlens: 1=10x

2.PhotolithographywithMask#4(Vias):

Spincoating

&

Soft

baking


Thefourthmaskcontainsthefeaturesofthevia

etch. The vias are holes in the SiO2 which allow the

aluminumpadstocontactthediffusedsiliconsurface.










Week11

2.PhotolithographywithMask#4(Vias):



Mask#4.



























thephotoresist.


47/64

Methods:

3.Hardbaking:







4.EtchingtheSiO2:











andnitrogengun.

Week11


48/64

SiO2Thickness( ):

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

NOTES/CHANGES:

___________________________________________________________________________

___________________________________________________________________________

______________________________________________________________________________________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

___________________________________________________________________________

____________________________________

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