Decontamination Solutions to Control AMCs in FOUPs

16 Pages·2017·1.21 MB·English

by  Anna Anderson

AUSTIN 28 & 29th MARCH 2017
Gas Purge or Wet Cleaning:
Decontamination Solutions
to Control AMCs in FOUPs
Surface Preparation and Cleaning Conference
Paola González-Aguirre, Entegris, [email protected]
Hervé Fontaine, CEA-Leti, [email protected]
Carlos Beitia, CEA-Leti, [email protected]
Jim Ohlsen, Entegris, [email protected]
Jorgen Lundgren, Entegris, [email protected]
OUTLINE
45 nm 32/28 nm 22/20 nm 16/14 nm 10 nm
◦ Introduction
Manufacturing/Development Research
◦ Goals
◦ Gas purge
◦ Wet clean
◦ Numerical simulation
◦ Summary
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INTRODUCTION: AMC
◦ Airborne molecular contamination (AMC) may be responsible for severe yield losses
◦ Among AMCs, HF is identified as root cause of defectivity, where moisture and time play a critical role:
Cu loss, Crystal Growth & Corrosion
[HF]
F- as catalyst
Removed by following
Cu + O + H O Oxidized Cu
2 2 wet cleaning (Cu-loss)
◦ F and Cl are common gases used for etching Time % RH
2 2
◦ Residual F and Cl will react with H O and form HF and HCl
2 2 2
H O H O
2 2
Cl HCl F HF
2 2
Crystal growth Al corrosion
Wafer defectivity
on TiN
Jun B., Bai H., Lin K.I., Lui S.S., AL-Cu Pattern wafer study on metal corrosin due to chloride ion contaminants. IEEE Transactions on Semiconductor Manufacturing., Vol 23
(2010), 553-558
Luo V., Ding J., Zhan W., Peng L., Wang A., Liu B., Song Y., Yin D., Method to redice crystal defects in AlCu bond pad. ECS Transactions. 27 (2010), 321-325
T. Kamoshima, Fujii Y., Noguchi T., Saeki T., Takata Y., Ochi H., Koiwa A., “Controlling ambient gas in slot-to-slot space inside FOUP to suppress Cu-loss after dual damascene
patterning,” IEEE Trans. Semicon. Manufact., vol. 21. (2008), 573-577
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INTRODUCTION: FOUP TO WAFER CROSS CONTAMINATION
Demonstration of a cross-contamination chain between FOUP and wafers

FOUP equilibration
◦ Solution-diffusion model (polymer membranes):
molecular transfer governed by gas solubility and
diffusion in polymers
◦ New generation FOUPs must minimize the impact of
the AMCs (not only particles) onto the wafers
◦ Air FOUP control or FOUP decontamination must be
implemented to limit AMC contamination
◦ Gas Purge
◦ Wet Clean

FOUP contamination Transfer from FOUP to wafers
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GOALS

◦Evaluate gas purge & wet clean efficiency for critical HF contamination in terms of contaminant
transfer to wafer
◦Quantitative assessment of cross-contamination phenomena depending on decontamination solution
 direct relevant data at the FOUP scale
◦Comparison of different FOUP materials in terms of contamination reduction
 SPECTRA PC  SPECTRA PC/CP A300 EBM/CNT
Polycarbonate Polycarbonate/C-powder EBM/C-nanotubes
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GAS PURGE TEST: EXPERIMENTAL
FOUP Conditioning Intentional Gaseous HF Contamination 25 300mm Si wafers
Clean room equilibration (21°C 40% RH) 10 µl- Droplet of HF 2% 6 200 mm Cu Wafer Storage
7 days (9.2 ppmv after total evap.) 2 hours LPE-IC 2 hours, 25 hours

Standard Purge 5L/min No Purge
door closed 24 hours door closed 24 hours
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GAS PURGE TEST: RESULTS OF THE HF TRANSFER ON STORED CU-WAFERS
No Purge Gas Purge
6.00E+14
5.00E+14
4.00E+14
²
m
c
/3.00E+14
tl
a
-
F
5 L/min purge is a
2.00E+14
very low flow
(Fab flows are
1.00E+14 around 50 L/min)
ITRS spec 24h
Ref
0.00E+00
Botton wafers Middle wafers Upper wafers Botton wafers Middle wafers Upper wafers
2 hours 24 hours 3 hours 25 hours 2 hours 24 hours 2 hours 24 hours 3 hours 25 hours 2 hours 24 hours
 EBMCNT  PCCP  PC
◦ HF transfer: EBMCNT < PCCP < PC
◦ HF transfer: EBMCNT < PCCP < PC
◦ 25 slot effect
◦ Remarkable 25 slot effect
◦ Significant HF transfer reduction (40-80% short time and
◦ Main transfer during first hours of exposition
20-40% long time)
◦ EBMCNT respect ITRS limits
◦ EBMCNT & PCCP respect ITRS limits
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WET CLEAN TEST: EXPERIMENTAL
With or w/o
Cu Wafer storage
Intentional Gaseous HF Contamination Wet cleaning
66 hours - LPE
(9.2 ppmv after total evap) 2 hours
0h
4h 3 hours
22h
DMS M300, Spray surfactant 1 min,
total rinse 3 min, total dry (70°C) 29 min
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WET CLEAN TEST: RESULTS OF THE HF TRANSFER ON STORED CU-WAFERS
without wet clean With Entegris wet clean
1.00E+15
9.00E+14
8.00E+14
7.00E+14
2 6.00E+14
m
c
m/5.00E+14
t
a
- 4.00E+14
F
3.00E+14
2.00E+14
ITRS
1.00E+14
spec 24h
Ref
0.00E+00
EBMCNT PC EBMCNT PC
 0 hours  4 hours  22 hours
◦ HF cross contamination: EBMCNT < PC ◦ Wet clean decreases HF transfer between 40 & 60%
◦ Contamination transfer decreases with the time: HF (depending on time) in PC and around 70% in EBMCNT
diffusion in bulk ◦ EBMCNT respect ITRS limits after clean

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WET CLEAN TEST: HF TRANSFER VS WAITING TIME
Before wet clean During wafer storage
(after 2h contamination) After wet clean (66h of wafer storage)
‒
t 0h
‒

*
r n
e
f o
s i
n t
a
a
n
r
T i
e m
FOUP rfac Polymer t 4h on a
u t
airborne r s bulk ti n
a a o
e
N n C
i
m P
U
a
• Sorption way t O
n
F
• Desorption way o
C
t 22h +
+
HF sorption HF removal HF transfer
0h < 4h < 22h 0h > 4h > 22h 0h > 4h > 22h
Kinetically dependent
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