deposition

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2023年4月13日发(作者:soho什么意思)

SurfaceandCoatingsTechnology,

64(1994)127-130127

Influenc梵高作品欣赏 eofdepositionparametersontherefractiveindexandgrowth

rateofdiamond-likecarbon:films

,

X.

Zheng,,

DepartmentofMaterialsScienceandEngineering,NorthwesternPolytechnicalUniversity,Xian710072(China)

(ReceivedSeptember6,1993;acceptedinfinalformNovember5,1993)

Abstract

Inordertoudiamond-likecarbon(DLC)filmsasprotectiveandantireflectioncoatingsforIRopticalmaterialxpodtohostile

environments,aninvestigationhasbeensystematicallyconductedontheinfluenceofthedepositionparametersontherefractive

indexandgrowthrateofDLCfilms,whicharetwoofthemostimportantparametersinevaluatingopticalcharacteristicsof

erimentalresultsshowthatboththerefractiveindexandgrowthrateofDLCfilmsdependstrongly

onthenegative

d.c,

ractiveindexincreaswithincreasingbiasvoltageanddecreaswithincreasingpartial

wthrateincreasgreatlywhenthebiasvoltageislarger

iousparameterswr

transformIRspectroscopyre手抄报爱祖国 sultsshowthatthestrengthofthe

C-Hstretchingabsorptionbandintherange3300-2850cm

-1

is

graduallergybombardmentofthegrowingfilm

playsanimportantroleinthestructureandhencethepropertiesofDLCfilms.

uction

Inrecentyearsdiamond-likecarbon(DLC)filmshave

beenthesubjectofextensiveinvestigationowingtotheir

unusualandhighlydesirablepropertiessuchaxtreme

hardness,resistancetochemicalattack,highthermal

conduction,highintrinsicelectricalresistivity,wideband

gapandopticaltransparencyintheIRregion,which

makethemufulforelectronicdevicesandvarious

opticalandmechanicalapplications[1,2].DLCfilms

canbedepositedatlowtemperatureandhighdeposition

rateoverlargeareasusingavarietyofplasma-enhanced

chemical

vapourdeposition(PECVD)techniques[3].

Anumberofattemptshavebe右文 enmadetodisclo

complexdeposition

parameters-structure-property

relationshipsinthefilms[4,5].Thepropertiesof

DLCfilmschangeasafunctionofdepositionparameters

suchaspowerdensity,ltage,feed

gasflowrate,

reactorpressure,ractive

indexofDLCfilmsvariesfrom1.6to2.9depending

onthedepositionmethodandconditions[2,6].

However,evenforthesamedepositionmethod,the

experimentallawsgoverningthechangeinrefractive

indexwithdepositionparametersarenotexactlyiden-

tical[7,

8].Therefore,beforedepositingantireflection

filmson

IRopticalmaterials,itisveryimportantto

understandfullytherelationshipbetweentherefractive

indexandgrowthrateofDLCfilmsandthedepositionparameters.

InthisworkDLCfilmsaredepositedbyther.f

earchemphasisisplacedon

therelationshipbetweenthepropertiesoftheDLCfilms

iationin

refractiveindex

opticalabsorptioncharacteristicsofthefilmsarealsoinvestigated.

mentaldetails

depositionsystem

ech-

nique.

Theexperimentalapparatusudinthisworkis

auimprovedGDM-300BN-typehighvacuumcoater

whichconsistsoffourctions:thevacuumsystem,the

gasinletsystem,thepowersource

andtheelectrodes.A

water-cooledcopperelectrodeactedassubstrate

holder

andwascapacitativelycoupledtothe13.56MHz

d.

r.f

powerwasmeasuredbyawattmeterandwasvaried

ltage

canbe

continuouslyadjustedinthewiderange300-1000V.

Acetyleneormethanegasdilutedwithhighpurity

argon

wrateofeachgaswas

controlledbya

D08-3/ZMtypemassflowcontroller.

Atypicalbackgroundpressurewas1.33x

10-

3

depositionparametersarelistedinTable1.

0257-8972/94/$7.00

SSDI0257-8972(93)02225.2

htsrerved

128

t01.

j

RefractiveindexandgrowthrateofDLCfilms

TABLE

1.

Plasmadepositionparameters

(W)

Biasvoltage

-Va(V)

Totalgaspressure(Pa)

Contentof

hydrocarbons

10%-100%C

2H

2

5%-100%CH4

Depositiontime(min)

Substrate

temperature

("C)<100

20-1200-10005.33-13.315-90

atematerialsandpretreatments

Monocrystallinesilicon(Si)andgermanium(Ge)

sheetswithdimensionsof10x20x0.34mm"and0

13x0.26mnr'

surfacesofGeandonesurfaceofSiwerepolishedtoa

pleswerethoroughlycleanedultra-

sonicallyinacetoneandthencleanedbyhighenergy

Ar"bombardmentfor5-15minpriortodeposition.

Thoroughsurfacecleaningwasfoundtobeanimportant

stepinimprovingtheadhesionbetweenthe

DLCfilmsandthesubstrates.

terizationofDLCfilms

TherefractiveindexandthicknessoftheDLCfilms

weremeasuredat0.6328urnusinga1T75-1-typelar

ellipsometer

andthemeasurementofthefilmthickness

IR

transmittance

intherange4000-400em

-1

wasmeasuredbyemploying

a60SXRFouriertransform

IR

(FTIR)spectrometer

(Nic1ot,USA).Thespectrawererecordedataresolution

of4em

-1andaveragedover32scans.

sanddiscussion

tiveindex

Theexperimentalresultsobtainedusingtheortho-

gonaltestmethodshowthatdepositionparameterssuch

asthepowerdensity,ltage,concen-

trationofthehydrocarbongasandflowrateofthe

mixtureareofgreatimportanceindeterminingthe

2.7

refractiveindexofDLC

paperthepower

densityisfixedat30Wem-

2

Torr

-1

andtheeffectofthe

otherparametersontherefractiveindexisinvestigated.

Figure1showsthedependenceoftherefractiveindex

oftheDLCfilmsgrownonsiliconandgermanium

ractive

indexofthe

DLCfilmsonSisubstratesincreasfrom

2.2at

Vb

=-

300Vto2.45at

Vb

=-

Vb

values

higherthan-500Vtherefractiveindexincreasslowly

toabout2.65(eFig.1(ve-mentionedexperi-

mentallawisingoodagreementwith

thatobtainedby

Koidl

etal.

[7].TherefractiveindexoftheDLCfilms

voltage

Vbintherange300-900V(eFig.l(b)).

ltagecancauahighenergy

ionbombardmentofthegrowingfilmsurface,whichwill

resultinanenhancementoftheadhesivestrength

betweenthe

bombardmentalsocausapreferentialsputteringof

weaklybondedcarbonphafromthefilmsurfaceand

henceincreastherelativeconcentrationof

Sp3bonds.

Alltheabove-mentionedfactorsleadtoanincreaintherefractiveindexoftheDLCfilms.

Figure2showstheinfluenceofthebiasvoltage

Vb

onthe

IR

transmittancespectrumoftheDLCfilmson

thepolishedSisurface(withtheothersurfaceunpol-

ished).Withincreasingbiasvoltagethetransmittance

decreasandtheintensityoftheabsorptionpeakat

2920em

-1

(or3.4urn),reprentingthestretchingvibra-

tionmodesofCHorCH

2

specieslocalizedattetrahedral

(Sp3)sites

[9],isgraduallyweakened.

Itisindicated

I

~

2.62.5

X

2.5

2.32.1

1.9

~

~

2.22.1

400

600

(a)

~

800

1000

BIASVOLTAGE(-V)

1.7300

500

(b)

700900

BIASVOLTAGE(-V)

Fig.

enceofrefractiveindexonbiasvoltagefor(a)DLCjSiand(b)DLCjGe.

et

al./Refractiveindexandgrow记叙文600字 thrateofDLCfilms

129

70

~

60~

eJ

50

j-300V

2-400Vg

~

3-SOOv

102.0

5.0

8.0

11

.0

14.0

WAVELENGTH(11m)

ittancespectraofDLC/Siundervariousbiasvoltages.

thattheionbombardmentcausaconsiderablecrack-

ingofC-Hbonds,leadingtoareducedhydrogencontentinthefilm.

Therelationshipsbetweentherefractiveindexandthe

contentofthehydrocarbongasandtotalflowrateof

refractiveindexdecreaswithincreasingflowrateratio

ofC

2H2

orCH

4

toC

llyspeaking,therefractive

2H

2

+

ArorCH

4

+

Arrespectively

indexincreaswithdecreasinghydrogenconcentration

[10].Thereforealowervalueofrefractiveindexis

caudbyahigherproportionofHatomsbondedinto

the

DLCfilmswithincreasingpartialpressureofhydro-

carbongasandtotalflowrate,whichhasbeenproved

intensityofthe

C-Habsorptionbandnear2900cm-

I

isgraduallyweakenedwithdecreasingflowrateratioof

C

2H2

toC

2H2

+

ArandtheIRabsorptionb胆红素高吃什么药 andwas

obrvedtodisappearwhentheratiowaslowerthan

25%C

near

2900

2H

2

.

Filmswithoutthe权御盛唐 C-Habsorptionband

em

-I

intheIRabsorptionspectrumwere

2.1

1.6

o

2

HYDROCARBONCONTENT(%)

Fig.

3.

DependenceofrefractiveindexofDLCfilmson

Si

substratesonhydrocarboncontent.

2.3

2.2

3.6

5.4

7.2

9.0

TOTALFLOWRATE(SCCM)

enceofrefractiveindexofDLCfilmsonSisubstrates

on

totalflowrate.

WAVENUMBER

(em-I)

Fig.

5.

InfluenceofC

2

H

2

contentonIRabsorptionspectrumofDLC

filmson

Gesubstrates.

consideredtobeunhydrogenatedamorphouscarbon

films[11,12].

It

canalsobeenfromFig.3thatthe

refractiveindexhasarelationwiththenatureofthe

ractiveindexofDLCfilms

depositedfromAr

-C

2H

2

islowerthanthatofDLC

filmsdepositedfromAr-CH

4

underidenticaldepositionconditions.

rate

Figure6showsthedependenceofthegrowthrateof

theDLCfilmsdepositedonGesubstratesonthenega-

ltage.

It

isobrvedthatthereisa

thresholdbiasvoltagevalueV

th

ofaround

-600

growthrateincreas天安门广场 withincreasingbiasvoltageand

for

Vb

higherthan

J-;h

thegrowthrateincreasrapidly.

Thethresholdvaluehasarelationwiththenatureof

thesubstratematerial,thesubstratesurfaceareawith

respecttothatofthecathodeelectrode,andthesubstrate

thicknesswithrespecttothedistancebetweenthe

llerthesurfaceareaandthethicker

thesubstrate,thelarger

J!;h

andthelowerthedeposition

7

showsthevariationinfilmthicknesswithdeposition

ltageof

-600

expected,thefilmthicknessincreaswiththedepos-itiontime.

250200

150

100"===::::::::"':"'-.-.

__

...L-...J

3

BIASVOLTAGE(-V)

enceofgrowthrateofDLCfilmsonGesubstratesonbiasvoltage.

130

tal./RefractiveindexandgrowthrateofDLCfilms

........

1.60

'-'

~

1.20

......

t3

0.80

~

~>x-c

2

DEPOSITIONTIME(min)

Fig.

7.

DependenceoffilmthicknessofDLCfilmsonGesubstratesondepositiontime.

Thenetgrowthratedependsontwocompetingpro-

cess,

<

depositionandetching,whichoccurduring

thewholeprocessofpreparingDLCfilmsfrombegin-

hingprocessplaysasignificantrole

intheopticalandmechanicalpropertiesoftheDLC

ltageandtheconcen-

trationofArgascanbeudtocontroltheetchingrate.

ThereforethenetgrowthratedependsonthebiasvoltageandArcontent.

Thedepositionparameterssuchaspowerdensity,

negativebiasvoltage,Arconcentration,totalflowrate,

nfluencethestructureandpropertiesofDLC

filmsareinterrelated,whichimpliesthatidenticalexperi-

mentalresultscanbeobtainedbyadjustingtheother

tance,toincreatherefrac-

tiveindexoftheDLCfilm,increasingthepowerdensity

orArconcentrationiquivalenttoincreasingthe

negativebiasvoltageundercertainconditions.

It

hasto

bedeterminedthroughacomprehensiveanalysisaccord-

ingtopracticalsituationxactlywhichdepositionpro-cessisadopted.

Accordingtotheabove-mentionedexperimentallaws,

wehavesuccessfullypreparedantireflectionandprotec-

tivefilmsonGesubstratesbyusingasuccessiveapproxi-

imumIRtransmittanceofGe

withasingle-layer

DLCfilmononesideandbothsides

hasreachedthetheoreticalvaluesof64%and99%

ransmittanceofanon-uniform

DLCfilm,whorefractiveindexchangesgradually

alongthefilmthickness,coatedonbothsidesofaGe

r85%.

sions

TherefractiveindexofDLCfilmsincreaswith

ltagebetweentheplasma

andtheelectrodeanddecreaswithincreasingcontent

ofthehydrocarbongasandtotalflowrateofthemixture.

Thegrowthrateincreaswithincreasingnegative

holdbias

voltagevalue

~h

existsinthedependenceofthegrowth

wthrateincreas

rapidlywhenthebiasvoltageislargerthanthethresh-oldvalue.

Thedepositionparameterswhichinfluencetheoptical

andmechanicalpropertiesofDLCfilmsareinterrelated.

Thehighenergybombardmentonthegrowingfilms

caudbythenegativebiasvoltageplaysaveryimpor-

tantroleinthestructureandpropertiesofDLCfilms.

Theintensityoftheabsorptionbandat

2900

em

-1

is

graduallyweakenedorevendisappearswithincreasingbiasvoltageandArconcentration.

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