functional water solutions to enable wet cleaning process

PowerPoint © 2018 KURITA WATER INDUSTRIES LTD. All Rights Reserved. 1
Functional water solutions to enable wet cleaning process for leading edge semiconductor device manufacturing
KURITA WATER INDUSTRIES LTD. Hideaki Iino, Yuichi Ogawa, Takeo Fukui
imec vzw Quoc Toan Le, Els Kesters , Yusuke Oniki, Frank Holsteyns
[email protected], +81-80-6884-0245
1. Functional water opportunity for new materials
LaO loss suppression by functional water
Co
MG Co
• Dipole for logic multi-Vt RMG and DRAM peri high thermal stability gate stack
• water soluble
Lanthanoids, alkali earth metals: La, Mg, Ba, ... 3d transition metals: Co, Cu, Ni, ...
New materials for contact and interconnect
easy to corrode
Co
Co
Functional water
Agenda
3. Cobalt corrosion and passivation
4. Atomic scale etching of Cobalt
5. Summary
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La2O3 dissolution and its suppression
La2O3 wafer (15 nm)
Wafer weight, XPS
La2O3 + 6H+ → 2La3 + +3H2O (CO2W, DIW)
La2O3 + 3H2O → 2La(OH)3 (ud-NH4OH)
La2O3 wafer (15 nm)
Wafer weight, XPS
• Passivation layer effectively suppresses La2O3 dissolution
La2O3 wafer (15 nm)
• Regarding the RMG La2O3 patterning PMOS : after TiN removal rinse by CO2W NMOS : after TiN removal rinse by ud-NH4OH
La2O3 wafer (15 nm)
Agenda
5. Summary
Z. Tokei (imec), IEDM 2017Co corrosion seen
Co compatible cleans required: 1. Contact Co PCMP 2. Co etchback (for SAGC) 3. Post via etch clean (SD) 4. Post via etch clean (gate) 5. M0 Co PCMP 6. Post V0 etch clean 7. M1 Co PCMP 8. Post V1 etch clean
0.05% HF, 20sec.
N2 ambient (DO < 30 ppb)
Cobalt corrosion and passivation
0.05% HF, 20sec.
Q.T.Le et al. (imec), UCPSS 2018
Co + 2H+ Co2+ + H2
CoO + H2O HCoO2 - + H+
Self-limiting & Fast Passivation
Native oxide removal Pre measurement Rinse XPS
• Co surface is passivated by a thin Co(OH)2 and CoO and layer
TO A
Native oxide removal Pre measurement Rinse XPS
0.05% HF
ud-APM
ud-NH4OH
• Co surface is passivated by a thin Co(OH)x and CoOx layer Self-limiting & Fast Passivation
Co(OH)x
Co
CoOx
ud-APM
ud-NH4OH
Surface stability0.05% HF, 20sec. Co loss test, 30 – 300 sec.
Process flow Native oxide removal Pre measurement Rinse Post measurement Wafer weight
• Co passivation layer is relatively stable under the atmosphere
Agenda
5. Summary
Atomic scale etching of Cobalt
A.Pacco et al. (imec), SPCC 2019
Oxidation Rinse Removal Rinse Dry
Oxidation RinseRemoval RinseDry
A.Pacco et al. (imec), SPCC 2019
E.Kesters, H. Iino et al. (imec), SPCC 2019
• No rinsing step between each etching step Improve the throughput and the cost of ownership!
© 2018 KURITA WATER INDUSTRIES LTD. All Rights Reserved.
Reference Co CMP 0.05M HF RT 300s 0.05 M HCl RT 300s CO2W RT 300s
17
Ref CO2W0.05 M HF 0.05 M HCl
• CO2W is less sensitive to the Co grain boundaries
Co coupon
XSEM measurement
ud-APM
• Co ER directly proportional to the etch cycle#
Before: Co CMP
CVD Co
After: Co Etch back ud-APM 60s + CO2W 60s (Functional water DE)
5 cycle 10 cycle 15 cycle
Co EB ud-APM 60s + CO2W 60s (Functional water DE) 5 cycle
• Fully functional water atomic layer etching is less sensitive to the Co grain boundaries/sizes. • Controlled local uniformity and negligible pattern loading seen.
ud-APM
Summary
HKMG patterning In case HKMG patterning required to suppress La2O3, ud-NH4OH rinsing could preserve the La2O3 layer. Meantime, removal La2O3, CO2W rinsing is preferred.
Co surface cleaning in the MOL and BEOL ud-APM successfully passivates the Co surface, resulting in negligible Co loss during the wafer rinsing step.
Controlled Co recess for SAGC and FSAV Fully functional water digital etching could demonstrate atomic scale etching of Co.
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functional water solutions to enable wet cleaning process

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