vapor phase thiol self-assembled monolayers for dod asd · udt + 50 hfn x t hfnx_on_sio2blanket =...
TRANSCRIPT
Vapor Phase Thiol Self-Assembled Monolayers for DoD ASD
Sebastiaan J. F. Herregods, Tinne Delande, Mattia Pasquali, Zsolt Tokei, Herbert Struyf, Silvia Armini
2
OUTLINE
▪ Introduction
▪ HfNx ALD
▪ UDT on blanket substrates
▪ UDT on Patterned substrates
▪ Summary
3
MOTIVATION
Downscaling makes top-down fabrication by litho more challenging
Bottom-up approach by Area-Selective Deposition (ASD)
Block film growth by SAM passivation
Dielectric on Dielectric (DoD) enabled by Thiol SAM passivation
RS-H + M(n)0 → RS-M+M(n-1)
0 + ½ H2
Application:
Self-Aligned Vias
Selective Anchoring group
Hydrocarbon chain
10 nm
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SAVANNAH S300
Veeco/Ultratech Savannah G2 S300
Cross flow reactor
300 mm
Integrated in a glovebox (EHS)
Quarts Crystal Microbalance (QCM)
2 SAMs kits (Thiol)
Metal Organic Precursor lines
H2O precursor line (Metal Oxides)
NH3 precursor line (Nitrides)
ATOMIC LAYER DEPOSITION (ALD) TOOL EQUIPPED WITH SAM-KITS
Ultratech’s Savannah with
opened cross flow reactor
opened cross flow reactor
Savannah S300 integrated in a glovebox
Pballast
Preactor
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SAM DEPOSITION
Quality of vapor deposited SAMs is strongly dependent on:
precursor dosage
duration of the exposure.
Typical Pressure profile during SAM deposition
precursor dosage duration of the exposure
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OUTLINE
▪ Introduction
▪ HfNx ALD
▪ UDT on blanket substrates
▪ UDT on Patterned substrates
▪ Summary
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HAFNIUM NITRIDE ALD
▪ Process
▪ Tdeposition = 120 °C
▪ 0,025 s NH3 pulse
▪ 0,300 s TDMAHf pulse (at 75 °C)
▪ 10 s 20 sccm N2 purge
▪ Spectroscopic Ellipsometry
▪ Linear growth: GPCHfNx on SiO2 = 0.22 nm
▪ n = 2.0
▪ Thickness gradient (Inlet/West < Center < Outlet/East)
▪ Good run to run reproducibility
▪ Similar results for Tdeposition = 150 °C
100 cycles ALD HfNx 120ºC
TEM image of 100 Cycles HfNx at 120 °C
21.4 nm
▪ k value = 6,4 ± 0.6 (Pt dots)
▪ XPS:
▪ Hf:N ratio ~ 1:4
▪ signal present indicating not all the ligands reacted
▪ Top layer oxidized (Hf:N:O ratio ~ 3:1:6)
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OUTLINE
▪ Introduction
▪ HfNx ALD
▪ UDT on blanket substrates
▪ UDT on Patterned substrates
▪ Summary
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UDT DEPOSITION ON CU BLANKETS
▪ Pretreatment
▪ Asis
▪ 15 minutes forming gas at 250 °C
▪ Process
▪ n-undecanethiol (UDT) at 80 °C
▪ 300 mTorr UDT build up (Tprecursor = 65 °C)
▪ 4 UDT pulses with each 600 s exposure (uniform WCA)
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UDT DEPOSITION ON CU BLANKETS
▪ UDT layer
▪ HfNx ALD blocking at 120 °C
> 100 nm HfNx
▪ UDT on Cu after CMP
▪ Thicker & more hydrophobic
▪ HfNx ALD blocking until at least 500 cycles (> 100 nm HfNx)
▪ UDT on Cu after forming gas pretreatment
▪ reduced blocking behaviour: 50 cycles HfNx blocked(~ 11 nm HfNx on SiO2), but not 100 cycles of HfNx
▪ Blocking up to 100 cycles observed at higher precursor T/dose (not shown, by SE)
Asis (after CMP) 15’ forming gas (FG) @ 250 °C
WCA [°] 106 ± 2 103 ± 2
Thickness by SE [nm] 8 ± 1.8 3.1 ± 1.2
Selectivity S = 𝜃𝐺 − 𝜃𝑁𝐺
𝜃𝐺+ 𝜃𝑁𝐺
𝜃 = surface coverage (RBS)
G = growth area
NG = non-growth area
G. Parsons, J. Vac. Sci. Technol.
A, Vol. 37, No. 2, 020911-1
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OUTLINE
▪ Introduction
▪ HfNx ALD
▪ UDT on blanket substrates
▪ UDT on Patterned substrates
▪ Summary
UDT REMOVAL
800 W H2-plasma
DOD ASD ENABLED BY THIOL PASSIVATION
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UDT only
SiO2
UDT
Cu
UDT + 50 HfNX
tHfNx_on_SiO2blanket = 11 nm
SiO2
UDT
Cu
HfNx
UDT + 25 HfNX
tHfNx_on_SiO2blanket = 5.5 nm
SiO2
UDT
Cu
HfNx
UDT + 100 HfNX
tHfNx_on_SiO2blanket = 22 nm
SiO2 Cu
HfNx
8 – 9 nm
tHfNx ~ tUDT
~ 20 nm
~ 6-7 nm
AFM STEP analysis – 160 nm CD, 500 nm Pitch
Increasing topography with ALD cycles
Topography in line with ALD target
→As expected for AS-ALD
UDT multilayer formation on Cu
HfNx
UDT thickness decreasing with ALD cycles
Step Height ~ 14 nm
3 nm Cu recess
→ 11nm HfNx on SiO2
HIGH LER
Incre
asing
HfN
xcycle
s
Confirmed on patterned
undesired passivation at the edge of the SiO2 growth surface → high LER
CD dependence: more substantial at lower CD (for constant PD)
Increasing Passivated edge
DOD ASD ENABLED BY THIOL PASSIVATION
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ASD OBSERVATIONS
160 nm CD, 400 nm Pitch 80 nm CD, 200 nm Pitch
HfNx on SiO2
Cu
40 nm CD, 100 nm Pitch
No ASDASD
Temperature dependence: more substantial at 150°C
150 °C ASD
160 nm CD, 500 nm Pitch
120 °C ASD
~ 10 % ~ 30 %
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UDT EXCESS: REMOVAL PRIOR TO ALD
UDT on Cu
Heigth ~ 10 nm
Width ~ 200 nm
High LER
UDT on Cu
Heigth ~ 7 – 8 nm
Width ~ 160 nm
UDT
DOD ASD ENABLED BY THIOL PASSIVATION
UDT (no treatment)
UDT
Post SAM treatment leads to UDT width decrease: match with measured CD
Post SAM treatment leads to drastic decrease in LER
AFM, 160 nm CD, 500 nm PitchAFM, 160 nm CD, 500 nm Pitch
UDT + Post SAM treatment
5’ forming gas treatment at 200 °C
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UDT EXCESS: REMOVAL PRIOR TO ALD
DOD ASD ENABLED BY THIOL PASSIVATION
UDT (no treatment) + ALD UDT + Post SAM treatment + ALD
Treatment leads to significant decrease of undesired passivation on SiO2 growth surface
Treatment leads to drastic decrease in LER after ALD
Similar effect at 80 nm CD, but no ASD at 40 nm CD
AFM, 160 nm CD, 500 nm PitchAFM, 160 nm CD, 500 nm PitchTDSEM, 160 nm CD, 500 nm PitchTDSEM, 160 nm CD, 500 nm Pitch
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UDT EXCESS: REACTION WITH SURFACE DURING ALD
DOD ASD ENABLED BY THIOL PASSIVATION
Pulsing UDT during half cycles leads to no HfNx ALD growth on SiO2 blanket
SiO2
SiO2
Purge
Purge
HfNx ALD
UDT
UDT
UDT thickness decreases during HfNx ALD
→ In situ passivation at edge of SiO2 growth surface?
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OUTLINE
▪ Introduction
▪ HfNx ALD
▪ UDT on blanket substrates
▪ UDT on Patterned substrates
▪ Summary
18
SUMMARY
DOD ASD ENABLED BY THIOL PASSIVATION
UDT multilayer formation on copper oxide
ASD achieved on 160 & 80 nm CD, not on 40 nm CD
Post SAM treatment
UDT confinement by forming gas
drastic LER decrease
match original CD and passivated area
In-situ UDT release during half cycle may lead to undesired passivation on
intermediates of HfNx ALD
CONFIDENTIAL – INTERNAL USE