Hybrid DHF and N2 Jet Spray Cleaning for Silicon Nitride ... · Hybrid DHF and N 2 Jet Spray...
Transcript of Hybrid DHF and N2 Jet Spray Cleaning for Silicon Nitride ... · Hybrid DHF and N 2 Jet Spray...
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02019 SPCC, April 2-3, Oregon, USA
+820314004080
Hanyang Univ., Ansan, 15588, KOREA
Kook-Hyun Ana, Dong-Kyu Leec, Hun-Hee Leec
Woo-Sik Choic, Tae-Hoon Jungc and Jin-Goo Parka, b, †
Hybrid DHF and N2 Jet Spray Cleaning for
Silicon Nitride and Metal Layer
ADepartment of Bio-Nano Technology and bMaterials Science and Chemical Engineering, Hanyang University, Korea
CSamsung Electronics, Hwaseong, Korea
THE SURFACE PREPARATION AND CLEANING
CONFERENCE (SPCC)
SPCC 2019│ Portland, Oregon, USA │ April 2-3, 2019
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1. Research Background
2. Experimental Materials/Procedure
4. Summary
1) Research motivation : limitation of the current cleaning methods
2) Research objectives : diluted HF jet hybrid cleaning
1) Particle removal efficiency of HF spray process
2) Correlation of “Etch rate” and “Particle removal efficiency”
3) Surface roughness of HF spray process
4) Evaluation of patterned wafer particle removal
3. Experiment Results and Discussion
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Research Background
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Clean processing method conversion
• Wafer size increased from 200 mm to 300 mm
• IC circuit line width is reducing : micron(µm) → nanometer(nm)
Need to control small contaminants for yield improvement
Switch from batch to single equipment
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Importance of fine particle control
• Scaling and structures are more complex
• Capacitor aspect ratio is increase
Fine particle removal much more important
DRAM device roadmap
Imec Magazine September 2018 Emerging memories for the zettabyte era
Year of early introduction
Cap
acito
r A
spect
Rat
ion
Cri
tica
l pitch
conta
ct n
ode
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Current jet spray issues
Particle remove cleaning technology
• APM spray
Corrosion defect occurs when used in metal layer
Physical Cleaning
Brush
Megasonic
Nozzle type
Bar type
Skirt type
Laser CleaningLaser Shock wave
Laser Heating
Cryogenic Gas Cleaning
Jet SprayDIW spray
APM spray
Mono-dispersion Droplet
Frozen Cleaning
Gas Cluster Ion Beam
Chemical CleaningAlkali Chemical
SC1
Ammonia
Electrolytic Solution
• DIW spray
Pattern damage occurs when physical force is increased
(Pattern damage)
IP.W. Mertens st al, VLSI Taiwan 2006
.
Current issues on jet spray
• DIW spray and APM spray
Low PRE on silicon nitride film
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Hideki Hirano et al., ” Damage-free ultra diluted HF/nitrogen jet spray cleaning
for particle removal with minimal silicon and oxide loss.”(2006).
Research objective
Efficiency of metal removal
• DHF : Metal contaminants removal no metal attack
Physical force vs. Particle removal efficiency
• HF spray : High PRE at silicon substrate
Evaluation and application of DHF Spray cleaning for SiN and metal wafers
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Experiment Materials
And Procedure
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Experimental materials
• Contamination solution: silicon powder mixed with DIW
• Wafer contamination: poured a contaminant on wafer surfaces (2 min/wafer)
• Adsorption of contaminants : store in clean room 24 hours
DIW Un-patterned wafer
(Low spin speed)
Silicon powderContamination
source
Stored in FOUP
for 24 hours
Contamination
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Experimental materials
Materials
PRE evaluation
• Si wafer (p-type (100))
• 90 nm SiN on Si
Etch amount
• 90 nm thermal Oxide (SiO2)
• 90 nm poly-Si
• 60 nm TiN
• 40 nm W
Field evaluation (Patterned)
• 40 nm-scale DRAM
(Poly, SiN, TiN and W)
Analysis equipment
Unpatterned wafer defect inspection(SP-5, KLA-Tencor)
Spectroscopy ellipsometer(Aleris, KLA-Tencor)
Lens collector
Ellipsoidal collector
Polarization
WidePMT
NarrowPMT
Oblique incidence
beam
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Experimental setup
Experimental parameters
• Nozzle
- Design: In-nozzle mixing
- Wafer ~ nozzle distance: 30~50 mm
• Gas
- Flow rate: 40~55 l/min
• Scan
- Speed: 40~100 mm/sec
- Frequency: 2~4 scans
- Scan profile: 170 mm 0 mm
• Wafer
- Rotation speed: 0~2000 RPM
• Liquid
- Flow rate: 30~60 cc/min
DIW Diluted APM Diluted HF
1. Temperature : 65°C
2. Concentration :
NH4OH : 0.3 ~ 1.7 wt%
H2O2 : 0.3 ~ 6.5 wt%
1. Temperature : 25°C
2. Concentration :
DHF : 0.08 ~ 1.6 wt%
1. Temperature : 25°C
Controlled parameters
300mm singe wet cleaning equipment
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Experiment Results and
Discussion
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Limit of physical cleaning (DIW-N2 spray Only)
Particle removal vs. pattern damage
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20
40
60
80
100
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20
40
60
80
100
25 30 35 40 45 50 55
Num
ber
of P
atte
rn
Dam
ages
(ea)
Par
ticl
eR
em
ova
lEffic
iency
(%)
(Si/
SiW
afer)
@>
45nm
Nozzle Height (mm)
PRE (%)
# of Damages
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20
40
60
80
100
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20
40
60
80
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35 40 45 50 55 60 65
N2 Flow Rate (l/min)
PRE (%)# of Damages N
um
ber
of P
atte
rn
Dam
ages
(ea)
Par
ticl
eR
em
ova
lEffic
iency
(%)
(Si/
SiW
afer)
@>
45nm
Particle removal
Physical cleaning
events
Pattern standing
strength
Fre
quency
PRE
Pattern Damage
Events
Chemical reaction needed to
better cleaning performance
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PRE on SiN film in HF spray
HT Nitride 900Å LayerParticle Source – Si Powder +DIW diluted Solution
PRE on SiN compared to other cleaning conditions
• DHF combined with N2 spray showed the best PRE
• Chemical etching is required on SiN
Before
After
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Dominant factor for PRE on SiN layer
Comparison of PRE according to etch amount on SiN and oxide films
• Oxide film : No correlation between surface etch amount and PRE
• Silicon nitride film : PRE has very strong correlation with etch amount
Support the estimated mechanism
< Oxide layer > < SiN layer >
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HF etch amount on metal layers
Etch amount according to HF process time
• TiN, W surface showed slight etch amount in HF
HF spray was expected to have high PRE on TiN, W films
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PRE on W patterned wafer in HF spray
DRAM 4x – W Layer / Particle : Si Powder
Comparison of PRE with DIW spray & HF spray
• HF spray showed far superior PRE on W patterned wafers
• Higher PRE was achieved by slight surface etching of the films
HF SprayDIW Spray
PRE - 34.28% PRE - 90.23%
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Surface roughness changes at different chemical
• SiN,Poly-Si layer : No difference between HF spray and reference
• Oxide layer : high roughness of 10.4nm after treated in HF spray
Need caution for roughness change when applying on oxide films
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Process application on patterned wafers
Metal Layer
(TiN)SiN LayerPoly Layer
15.5% ↓ 11.1% ↓ 15.5% ↓ HF SprayConventional Spray
PRE results (HF spray vs. conventional spray)
• DRAM 4x – Poly-Si, SiN, TiN layer particle trend (1month, over 3000 wafers)
• SiN layer : 11.1% improvement with HF spray
• Poly-Si, TiN layer : 15.5% improvement with HF spray
Nu
mb
er
of
parti
cle
s (e
a)
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Summary
Need new type of cleaning method
• Increased PRE on SiN/Metal layers
• No pattern damage on reduced design rule
• No attack on metallic films
High particle removal performance requires
• Chemical cleaning cooperated with physical force
• Slight etching of the surface on SiN/Metal films
New hybrid cleaning of “ Diluted HF/N2 jet spray” can be answer
• High PRE on SiN and Metal layer without pattern attack
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2019 SPCC, April 2-3, Oregon, USA