Self-assembled monolayers: surface engineering and

SelfSelf--assembled assembled monolayersmonolayers: surface : surface engineering and characterizationengineering and characterizationC.M. Whelan*, T. Fernandez Landaluce#, A. Caro Maestre,

V. Sutcliffe# and Fabrice SinapiIMEC, Kapeldreef 75, B-3001 Leuven, Belgium.

J. Ghijsen and J.-J. PireauxLISE, FUNDP, Namur, Belgium.

M. de Ridder and H.H. BrongersmaCalipso B.V., Eindhoven, The Netherlands.

*Corresponding author. E-mail: [email protected]#Texas Instruments assignee at IMEC.Current address: #Materials Science Centre, University of Groningen, The Netherlands.

Frontiers of Characterization and Metrologyfor Nanoelectronics 2007 2

Self-assemblyspontaneous

chemisorption of active surfactant on a solid from

gas/liquid phase

Terminal functional groupexposed SAM-gas/liquid interfacemethyl, phenyl, amine, carboxylic acid, alcohol, …

Head groupbonding to specific substrate sites thiol/metals, silane/SiO2, acid/metal oxide

SAMsSAMs: surfaces : surfaces ““mademade--toto--orderorder””

Self-assembled monolayersmonomolecular organic film

Hydrocarbon segmentslateral interactions and tilt to minimise free volumegenerally alkyl chains with VdWs interactions

CH3

(CH2)n

SCu

18.4 Å2θ ~ 12°

Organic surfaces ‘made-to-order’

‘pseudo-(100)’ octanethiolate on Cu(111)1

1F. Schreiber, Prog. Surf. Sci. 65 (2000) 151

Composition controls structure and chemistry Manipulate atomic scale propertiesEngineer surfaces and interfaces


OutlineOutline

ALD of WCxNy/various-SAMs

Atomic layer depositionSAM compatibility with ALDEffect of SAM termination Influence of alkyl chain length

SAMs as Cu diffusion barrier

Previous workAdhesion & Cu silicide formation

Characterization of Cu/CO2H-SAM

LEIS: SAM outer most surfaceXPS: SAM-metal bonding

Conclusions

Application of SAMs in Nanoelectronics: surface engineering

Passive

Active

Characterization


ALD depends on surface chemistry1 - combination of precursors and their sequence and the type and density of reactive substrate surface sites

For interconnect metallization - ALD of WCxNy as Cu diffusion barrier form on low-k substrates2

WF6 + NH3 + B(C2H5)3 + surface groups → WCxNy

Selective (enhance/inhibit) WCxNy ALD - identify favourable/unfavourable surface groupsusing monofunctionalised surfaces

1Puurunen R.L., J. Appl. Phys. 97 (2005) 121301.2Martin Hoyas et al., J. Appl. Phys., 95 (2004) 381.

Use self-assembled monolayers as model substrates for studying ALD processes

Atomic Layer Deposition (ALD) for interconnect Atomic Layer Deposition (ALD) for interconnect metallization in IC technologymetallization in IC technology

IBM, 2002Bell Labs,1947

Shrinking dimensions → Al/SiO2 → Cu/low-k → conformal Cu diffusion barrier → ALD

Scaling requires newmaterials and processes


ExperimentalExperimental

ALD/SAM preparationSubstrate : SiO2 /Si(100)1

ALD : WCxNy from triethylborane (TEB), tungsten hexaflouride and ammonia at 300ºCSAM : alkyltrichlorosilanes ALCVDTM Pulsar® 2000 reactor

ASM PolygonTM 8200

SAM precursor X(CH2)nYterminal group X = CH3, Br, CNCH2 chain length n = 7-17head group Y = SiCl3

alkyltrichlorosilanes CH3-Cn-SAM CH3(CH2)nSiCl3n=7,9,10,11,15,17,21

bromoundecyltrichlorosilane Br-C11-SAM Br(CH2)11SiCl3cyanoundecyltrichlorosilane CN-C11-SAM CN(CH2)11SiCl3

ALD ALD WCWCxxNNyy::

ALCVDTM Pulsar® 2000 reactor integrated with an automated wafer handling platform (ASM PolygonTM 8200). A precursor (mixed with a nitrogen carrier gas flow) pulse sequence of (C2H5)3B, WF6, and NH3 represents one deposition cycle. Excess precursor gas was removed by flowing nitrogen after each precursor pulse. The deposition temperature was 300ºC.

Analysis:Analysis:H2O contact angle, XPS, TDS, Rs, XRF, ellipsometry, AFM, SEM, EF-TEM, TOF-SIMS, XRR, AES


ExperimentalExperimental

ALD ALD WCWCxxNNyy::

ALCVDTM Pulsar® 2000 reactor integrated with an automated wafer handling platform (ASM PolygonTM 8200). A precursor (mixed with a nitrogen carrier gas flow) pulse sequence of (C2H5)3B, WF6, and NH3 represents one deposition cycle. Excess precursor gas was removed by flowing nitrogen after each precursor pulse. The deposition temperature was 300ºC.

Analysis:Analysis:H2O contact angle, XPS, TDS, Rs, XRF, ellipsometry, AFM, SEM, EF-TEM, TOF-SIMS, XRR, AES

SiO2

Si

Si

O

O O

CH3 CH3

OO SiSi

CH3

Si

CH3

O

O O O

SiCl

Cl

Cl

CH3

H2O

CH3

OH

OH

OH Si

SiO2/Si(100) immersed in 10-3 M in toluene 1 hr. Rinsed with toluene, acetone, ethanol. Dried under nitrogen flow.


1Kluth et al., Langmuir, 13 (1997) 3775.2Whelan et al., Mat. Res. Soc. Symp. Proc., 812 (2004) F2.2.1.

SAM compatibility with ALD: MeSAM compatibility with ALD: Me--CCnn--SAM thermal stability SAM thermal stability TDS masses 11TDS masses 11--100100

M=40

0

4000

8000

12000

0 200 400 600 800 1000

Temperature (C)

Cou

nt ra

te (c

ps)

C8

C12 (Specimen2)

C16 (Specimen2)SiO2 (Specimen 2)

YYYYY96-98

YYYYY79-85

YYYYY66-71

YYYYY53-58

YYYYY47

YYYYY39-43

YYYYYes26-29

1715119n=7MassRange

All CH3-Cn-SAMs (n = 7-17) show :No water desorptionLeading edge ~ 500°CMaximum 600°C

Decomposition 470-690ºCFor fixed n, substitution of CH3 with Br or CN reduces thermal stability2

Previous EELS study in vacuum of decomposition mechanism for n=3,7,171

Stable to 470°C C-C bond cleavage → HC desorptionCreates surface CH3-Si groups to 620°CSiloxane head groups to 830°C


SAM compatibility with ALD: WCSAM compatibility with ALD: WCxxNNyy/Br/Br--CC1111--SAMSAMContact angle, XPS, TDSContact angle, XPS, TDS

XPS composition analysis of Br-UTS SAMs before and after WCxNy ALD. ALD cycles O % C % Siox% Sisubstrate% Br % W % N %

0 26.77 40.35 11.9 18.8 2.0 50 33.15 42.2 9.8 13.5 0.46 0.79

100 41.95 44.08 3.5 4.2 6.23 200 41.75 41.29 11.13 5.80 500 43.17 36.15 13.21 7.37

XPS composition analysis of Br-C11-SAM before and after WCxNy ALD

Water contact angle for as-prepared Br-C11-SAM86.2 ± 1.2° literature86.6 ± 1.5° experimental

All SAMs show:

Well-ordered surfaces with expected terminationNo chlorine presentDesorption maximum 550-600°CSurvive multiple ALD cycles

Suitable model substrates for studying ALD of WCxNy

200 ALD cycles/Br-C11-SAM

50 ALD cycles/SiO2

0

1000

2000

3000

4000

5000

6000

7000

200 ALD cycles/SiO2

Mas

s 68

inte

nsity

(a.u

.)

0 200 400 600 800

50 ALD cycles/Br-C11-SAM

Temperature (degrees C)

Br-C11-SAM


Effect of SAM termination on Effect of SAM termination on WCWCxxNNyy growth: W content growth: W content XRFXRF

0 200 400 600 800 1000 1200 1400

W (a

tom

s cm

-2)

0 200 400 600 800 1000 1200 1400

CN-C11-SAM

0 200 400 600 800 1000 1200 1400

CH3-C10-SAM

0 200 400 600 800 1000 1200 1400

SiO2

0 200 400 600 800 1000 1200 14000

1x1017

2x1017

3x1017

4x1017

5x1017

6x1017

Br-C11-SAM

No. of WCxNy ALD cycles

Initial non-linear growth Transient regimeWCxNy/substrate

Linear regimeWCxNy/ WCxNy

1 CPS = 2.70E+15 atoms 1.11E+15 atoms = 1 MLE

Initial non-linear growth on all SAMsLinear growth regime from 100-200 cycles for C10 & C11 SAMsGrowth on CN-terminated SAM favoured

CH3-C17-SAM

W (M

LE)

CN-C11-SAM

CH3-C10-SAM

SiO2

0 200 4000.0

5.0x101

1.0x102

1.5x102

2.0x102

Br-C11-SAM

No. of WCxNy ALD cycles

Effect of terminal group but also influence of alkyl

chain length?

Off-set from linearity


Influence of SAM alkyl chain length on Influence of SAM alkyl chain length on WCWCxxNNyy growth: growth: selectivity selectivity XRF XRF

0 100 200 300 400 5000

200

400

600

800

1000

1200

1400

CH3-C17-SAM CH3-C15-SAM CH3-C11-SAM CH3-C9-SAM CH3-C7-SAM

W (a

tom

nm

-2)

No. WCxNy ALD cycles

Transient regimeoffset

6 8 10 12 14 16 180

50

100

150

200

250

W (a

tom

nm

-2) @

150

ALD

cyc

les

n

0 100 200 300 400 5000

200

400

600

800

1000

1200

1400

CH3-C17-SAM CH3-C15-SAM CH3-C11-SAM CH3-C9-SAM CH3-C7-SAM

W (a

tom

nm

-2)


Selectivity for WCxNygrowth varies with n

Offset from linearity increases with increasing chain length

C17 most crystalline with few defects available for metal nucleation –retarding film growth

C7 least ordered SAM with higher population of defects available for metal nucleation

But defects unlikely to be linear over n = 7 to 17

CH3(CH2)nSiCl3


Influence of SAM alkyl chain length on Influence of SAM alkyl chain length on WCWCxxNNyy growth: growth: mechanism mechanism AFMAFM

+ 500

CH3-C15-SAM

After cycles of ALD WCxNy

+ 200 + 500

+ 100

As-prepared

Islanding growth mechanism Constant island densityLateral and vertical growth before coalescence

Same for all CH3-Cn-SAM with chain length dependent offset

100 X 100 nm2

-0.2

0.2

0.6

1

1.4

1.8

-50 50 150 250 350 450 550ALD cycles

RM

S (n

m)

CH3-C7-SAM

CH3-C11-SAM

CH3-C15-SAM


0 100 200 300 400 5000

200

400

600

800

1000

1200

1400

CH3-C11-SAM CH3-C7-SAM CN-C11-SAM

W (a

tom

nm

-2)


Influence of SAM alkyl chain length Influence of SAM alkyl chain length vs.vs. terminal terminal group on group on WCWCxxNNyy growth: selectivity growth: selectivity XRFXRF

Selectivity for WCxNy growth varies with n BUT influence of n not

exclusive CN-C11-SAM

vs.

CH3-C11-SAM CN-C11-SAM similar to CH3-C7-SAM shows terminal group enhancement

of growth

Both terminal group and alkyl chain length determine WCxNy

growth behaviour


(1) ALD/SAM: conclusions(1) ALD/SAM: conclusionsSilane SAMs investigated as model substrates for WCxNy ALD for : SiCl3 head group, chain lengths (n = 7-17) and terminal groups (CH3, CN, Br)

SAMs stable to >470°C and present after multiple 300°C ALD cycles

SAM termination effects WCxNy growth : CN-termination favouredCN-, Br- & CH3-terminated C10 & C11-SAM vs. CH3-C17 SAM

Selectivity for WCxNy growth varies with n due to thickness rather than structural defects within the SAMs

Both terminal group and alkyl chain length determine WCxNy growth behaviour

SAMs provide suitable model substrates for studying metal deposition

Vary substrate structure (alkyl chain) & chemistry (terminal group) to selectively control growth


OutlineOutline







Conclusions


Passive

Active

Characterization


Previous work Previous work SAMsSAMs as Cu diffusion barrier as Cu diffusion barrier 1Krishnamoorthy, Appl. Phys. Lett., 78 (2001), 2Ramanath, Appl. Phys. Lett. 83 (2003)

Cu diffusion barrier properties chain length & terminal group dependent1

Most promising candidate, SAM-SH, enhances Cu-SiO2adhesion & acts as Cu diffusion barrier2

No chain, bulky head group

Chain, no bulky head group

Chain and bulky head group

Chain and bulky head group with reactive heteroatomSAM1

SAM2

SAM3

SAM4

Cu seed layerevaoporated

diffusion barrier

bulk Cu (electroplated)

Si

Cu interconnect structure

SiO2

SAM1 SAM2 SAM3 SAM4


Concept: Concept: seleciveselecive process for process for DD integrationDD integrationC.M. Whelan, V. Sutcliff, U.S. Patent 2006/0128142 A1, European Patent 1 670 054 A1

SAM-Ssacrifical: CH3(CH2)9SHSAM-Bbarrier: HS(CH2)3Si(OCH3)3

Si(OCH3)3-SiO2

HS-Cu

Cu

SiO2

SAM-B

Cu

SiO2Si(OCH3)3-SiO2

HS

CH3

HS-Cu

SAM-S

SAM-B


Concept: Concept: seleciveselecive process for process for DD integrationDD integrationC.M. Whelan, V. Sutcliff, U.S. Patent 2006/0128142 A1, European Patent 1 670 054 A1

SAM-Ssacrifical: CH3(CH2)9SHSAM-Bbarrier: HS(CH2)3Si(OCH3)3

Si(OCH3)3-SiO2

HS-Cu

Cu

SiO2

SAM-B

Cu

SiO2Si(OCH3)3-SiO2

HS

CH3

HS-Cu

SAM-S

SAM-B

SAM-S thermal release


Assessment of Assessment of SAMsSAMs with systematic variation of with systematic variation of molecular structuremolecular structure

Same terminal & head groups but different chain lengths

CH3(CH2)nSiCl3 where n = 7,9,10,11,15,17,21

Same terminal & chain length but different head group

CH3(CH2)17SiX3 where X = Cl3, Cl2(OCH3), (OCH3)3

Same head group & chain length but different terminal group

CH3(CH2)11SiCl3 vs. CN(CH2)11SiCl3 vs. Br(CH2)11SiCl3SH(CH2)3Si(OCH3)3 vs. NH2(CH2)3Si(OCH3)3 vs. C5H4N(CH2)2Si(OCH3)3

Longer chain length (CH2)n for improved film order & Cu blocking efficiency

New head group -SiCl3 for improved adhesion, coverage-packing density & thermal stability

SH(CH2)n>6SiCl3 not commercially available


SiO2/CN-SAM/CuN 1s peaks Cu and the SiO2 sideStrong head group-SiO2 & CN-Cu bonding

SiO2/Br-SAM/CuBr 3d peaks Cu sideWeak head group-SiO2 & strong Br-Cu bonding

SiO2/SH-SAM/Cu

S 2p peaks Cu sideWeak head group-SiO2 & strong S-Cu bonding

Cu-SH = Br > CNSH-SAM failure at oxide in agreement with literature

4 points bending probe: fracture surface analysis4 points bending probe: fracture surface analysis

P.G. Ganesan et al., Mater. Sci. Forum 426-432 (2003) 3487, G. Ramanath et al. Appl. Phys. Lett. 83 (2003) 383

Cu/SH-SAM/SiO2structures delaminate at SAM/SiO2interfaceS atoms strongly bound to Cu & Si(OCH3)3 easily detach from the SiO2 surface


A crude look at Cu/A crude look at Cu/SAM/SiOSAM/SiO2 2 barrier properties: barrier properties: visual inspectionvisual inspection

SH

NH2

blank

Pyridine

325

300

375

350

SHPyridine

Cu

Pyridine

NH2

SH

Cu

Cu

SH

Pyridine

NH2

NH2

Annealing Temp. (°C)

HNC5H4CH2Si(OCH3)3

H2N (CH2)3Si(OCH3)3

HS(CH2)3Si(OCH3)3


0

50

100

150

200

250

300

0 200 225 250 275 300

Temperature

Shee

t rsi

stan

ce

Si/SiO2/MPTMS/Cu Recipe I UV-O3cleaning

Si/SiO2/Cu Recipe I UV-O3cleaning

A crude look at Cu/A crude look at Cu/SAMSAM--B/SiOB/SiO2 2 barrier properties: barrier properties: RRss vs.vs. temperaturetemperature

Cu silicideformation

Cu/SiO2

Cu/SAM-SH/SiO2


Darkened except for NH2

No change

No change

No change

Visual inspection upon anneal

Cu silicide formation >300oC* for SH & HNC5H4 slight inc.

No Cu silicideformation <400oC

No Cu silicideformation <400oC

but Si(OCH3)3>300oC slight inc.

No Cu silicideformation <

400oC

Sheet resistance(Ω/□)No

FailSame SiCl3 head group & chain length, n=11, but different terminal

groups, Br, CN, & CH3

Fail exceptSi(OCH3)3

Same CH3 terminal & chain length, n=17, different head group, SiCl3,

Si(OCH3)Cl2 & Si(OCH3)3

PassSame Si(OCH3)3 head group & similar chain length, n=1 or 3, but

different terminal groups, NH2, SH & HNC5H4

FailSame CH3 terminal and SiCl3 head groups but different chain lengths,

n= 7-21

Tape testSample

SAMsSAMs compared: adhesion & Cu compared: adhesion & Cu silicidesilicide formationformation


(2) (2) SAMsSAMs as Cu diffusion barrieras Cu diffusion barrier -- conclusionsconclusions

Molecules with SiCl3 head group show enhanced inhibition of silicide formation (> 400°C) - related to the relatively high thermal stability of the SAM (550-600°C) and dense SAM packing

No obvious effect of chain length n = 7-21 or terminal group CH3, Br & CN

Significant effect from head group, all molecules (including CH3 terminated) with Si(OCH3)3 head group pass tape tests - less densely packed SAMs may allow Cu penetration promoting adhesion

In general, molecules with Si(OCH3)3 head group, even with reactive terminal groups, show lower inhibition of silicide formation (250-300oC) compared with molecules with SiCl3 head group (>400oC). But adhesion on Si(OCH3)3 >> SiCl3.


OutlineOutline







Conclusions


Passive

Active

Characterization


LEIS: preparation of the Au(111) substrateLEIS: preparation of the Au(111) substrate

LEIS spectra measured with 3 keV 4He+ ions from a (111)-textured Au surface as-received, following oxidation treatment with an atomic oxygen source, and after cleaning by 20Ne+

sputtering cycles and annealing to ∼500 K for 30 min.

1000 1500 2000 2500 30000

100

200

300

400

500

600

Au

O

Inte

nsity

(Cts

/nC

)

Energy (eV)

as-received oxidized

sputtered (9.4*1014 ions/cm2) annealed

M. de Ridder and H.H. Brongersma

Calipso B.V., Eindhoven, The Netherlands.


LEIS: gas phase adsorption of 3MPALEIS: gas phase adsorption of 3MPA

500 1000 1500 2000 2500 30000

20

40

60

80

O

Inte

nsity

(Cts

/nC

)

Energy (eV)

0.05*1015 ions/cm2

0.11*1015

0.16*1015

0.27*1015

800 1000 1200 140020

25

30

35

40

Inte

nsity

(Cts

/nC

)

Energy (eV)

0.05*1015 ions/cm2

0.11*1015

0.16*1015

0.27*1015

2200 2400 2600 2800 30000

20

40

60

80

Inte

nsity

(Cts

/nC

)

Energy (eV)

0.05*1015 ions/cm2

0.11*1015

0.16*1015

0.27*1015

LEIS spectra measured with 3 keV 4He+ ions showing (a) the entire spectrum, (b) the oxygen peak, and (c) the high-energy onset of the background for a 3-MPA SAM adsorbed from the gas phase on Au(111). The spectra are normalised to the maximum background intensity of the first spectrum measured.

(b)

Full spectrum

Oxygen

High energy onset


LEIS: gas LEIS: gas vs.vs. liquid phase adsorptionliquid phase adsorption

Change in the oxygen peak area with increasing ion dose for 3-MPA and 11-MUA SAMs adsorbed from the gas or liquid phase on Au(111). Measurements were done with 3 keV4He+ ions. Peak areas were determined by fitting with a Gaussian after linear background subtraction.

0.0 0.5 1.0 1.5 2.00

50

100

150

200

250

Oxy

gen

peak

are

a (a

.u.)

4He+ ion dose (*1015 ions cm-2)

Adsorption phase 3-MPA gas 3-MPA liquid 11-MUA liquid

Surface oxygen contentSurface oxygen content

LEIS spectra measured with 3 keV 4He+ ions showing the high-energy onset of the background for 3-MPA and 11-MUA SAMs adsorbed from the gas or liquid phase on Au(111). A spectrum from clean Au(111) is shown for comparison with the Au peak normalised to the same height as the SAM/Au spectra at 2200 eV.

2200 2400 2600 2800 30000

20

40

60

80

Nor

mal

ised

inte

nsity

(Cts

/nC

)

Energy (eV)

Adsorption phase 3-MPA gas 3-MPA liquid 11-MUA Liquid Au

Film thicknessFilm thickness


LEIS: gas LEIS: gas vs.vs. liquid phase adsorptionliquid phase adsorption

Change in the oxygen peak area with increasing ion dose for 3-MPA and 11-MUA SAMs adsorbed from the gas or liquid phase on Au(111). Measurements were done with 3 keV4He+ ions. Peak areas were determined by fitting with a Gaussian after linear background subtraction.

0.0 0.5 1.0 1.5 2.00

50

100

150

200

250

Oxy

gen

peak

are

a (a

.u.)

4He+ ion dose (*1015 ions cm-2)

Adsorption phase 3-MPA gas 3-MPA liquid 11-MUA liquid

Surface oxygen contentSurface oxygen content

Sample Thickness (Å) Theoretical thickness (Å)

3-MPA(g) 4 ± 1 4.5

3-MPA(l) 6.5 ± 2 4.5

11-MUA(l) 11 ± 2 13.9


XPS: gas phase adsorption of 3MPAXPS: gas phase adsorption of 3MPA

160 162 164 166 528 530 532 534 536 538

533.3532.0

163.7

162.5O 1sS 2p

Inte

nsity

[Arb

. Uni

ts]

Binding Energy [eV]

292 290 288 286 284 282 280

C 1s

284.6285.2

289.1

Inte

nsity

[Arb

. Uni

ts]

Binding Energy [eV]

CO2H

CO2H-CH2CH2SH

thiolate C=Ocarbonyl

C-OHhydroxyl

2 types of oxygen

3 types of carbon

1 type of sulphurJ. Ghijsen and J.-J. PireauxLISE, FUNDP, Namur, Belgium.

C.M. Whelan et al., Thin Solid Films (2005) HOCS

Au(111)

mercaptopropionic acid CO2H-(CH2)2-SH

12

3

12

1


HO

CS

Au

Cu

O-Cu-O bidentate

Cu-OhydroxylCu-Ocarbonylunidentate

Cu/COCu/CO22HH--SAMs: possible bonding interactionsSAMs: possible bonding interactions


XPS: evaporation of Cu on 3MPAXPS: evaporation of Cu on 3MPA

292 290 288 286 284 282 280

C1s

0

0.35

0.72

1.4

2.2

3.6

5.0

Cu [ML]

Inte

nsity

[Arb

.Uni

ts]

Binding Energy [eV]

CO2H-Cu bonding

538 536 534 532 530 528

Cu [ML]

5.0

3.6

2.2

1.4

0.72

O1s

0.35

0In

tens

ity [A

rb. U

nits

]

Binding Energy [eV]

Cu-O bonding



538 536 534 532 530 528

Cu [ML]

5.0

3.6

2.2

1.4

0.72

O1s

0.35

0In

tens

ity [A

rb. U

nits

]

Binding Energy [eV]

Cu-O bonding

538 536 534 532 530 528

Cu [ML] 0 0.35 0.72 1.4 2.2 3.6 5

Binding Energy [eV]

Cu interacts with CO2H group

Selective deposition at OH site



940 936 932 928 572 568 564

1.0

0.350.721.42.2

3.65.0

Cu [ML]

Cu 2p3/2Cu LMM

Inte

nsity

[Arb

. Uni

ts]

Binding Energy [eV]

960 955 950 945 940 935

Cu2O/CuO

Cu0/Cu2O

Binding Energy [ev]

Cu(II) shake-up

932.5 eV

Cu-O interaction weak and/or Cu clustersCu oxidation state Cu(0)-Cu(I)no Cu penetration to Au surface

568.5 eV(918.1 eV)

568.8 eV (917.8 eV)


LEISDifferent CO2H-SAMs for gas vs. liquid phase formation :

Thickness 4 vs. 6.5 ÅSurface oxygen content x 5 difference

XPSThiolate surface intermediate with an intact carboxylic acid function

Cu adsorption : induces changes in carboxylic acid C 1s preferential modification of the hydroxyl group indicating unidentate complexationCu 2p comparable with bulk suggests cluster growth and weak Cu-CO2H-SAM interactionsNo penetration to the Au surface

(3) Cu/CO(3) Cu/CO22HH--SAM characterization SAM characterization -- conclusionsconclusions


Final remarksFinal remarks

ALD of WCxNy/various-SAMsTerminal group and alkyl chain length determine growth behavior

Vary substrate structure & chemistry to selectively control growth

SAMs as Cu diffusion barrierCu silicide formation: SAM-SiCl3 show enhanced inhibition attributed to high thermal stability and dense packing of SAM but no no obvious effect of chain length or terminal groupAdhesion: significant effect from head group, SAM-Si(OCH3)3 less densely packed may allow Cu penetration, XPS fracture analysis shows failure at SAM/SiO2 interface (vs. Cu/SAM for SiCl3)

SAM composition impacts adhesion & barrier properties

Characterization of Cu/CO2H-SAMLEIS reveals SAM outer most surfaceXPS identifies exact SAM-metal bonding


AcknowledgementsAcknowledgements

F. Clemente, A.-C. Demas$, A. Martin Hoyas, J. Schuhmacher,

L. Carbonell, T. Conard, B. Eyckens, O. Richard, Y. Travaly, D. Vanhaeren,

Rudy Caluwaerts, Caroline de Meurisse, and IMEC P-line.

This work has been carried out within IMEC’s Advanced Interconnect Industrial Affiliation Program.

$CEA/DRT/LETI/DPTS/SCPIO/LCPO, Grenoble, France.

THANK YOU !

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