how much do we really know about the chemical reactions ... · tsv for 3d chips basf cmp slurry...
TRANSCRIPT
1
How Much Do We Really Know About the Chemical Reactions Occurred During Cu CMP?
Prof. Dr. Yuzhuo Li
Global Electronic Business Unit
BASF, Ludwigshafen
2
Presentation Outline
� BASF CMP slurry development setup
� Representative results
� Innovative particles for copper slurries
� Progress in barrier slurries
� Polishing debris management for STI
� Fundamental understanding of CMP
� Conclusions and Acknowledgement
3
Cu CMP for interconnect (Cu)Barrier CMP for interconnect
Shallow trench isolation (STI)
TSV for 3D chips
BASF CMP Slurry DevelopmentAccording to Application
High K metal gate
Interlayer dielectric (ILD)
Established Applications
New Applications
Type of CMP Slurry for:
4
BASF CMP Slurry Development Setup
� Structured process checks chemical and applications viability
� Practical and focused approach accelerates commercialization
PolishingFormulation
BASF Chemistry
BASF R&D Lab
BASF Application LabTaiwan (200 mm)
BASF R&D Polishing Lab Germany (200 mm)
BASF Contract LabsUSA (200/300 mm)
Customers’ Needs(Process Targets)
Data packageDemo sample
Particle Technology(Internal / Outsourced)
Promising prototypes Robust prototypesCompatibility
BASF Product ManagementGlobal
5
Silica Particle Polymer Particle BASF Adaptive Organic Particle
Wafer
Stress-free Stress-free Stress-free
Compressed during CMP
Compressed during CMP
Compressed during CMP
Pad
No Deformation Deformation
Dissociation Wafer
Pad
Wafer
Pad
©KT 2008
Chemistry Innovation in CMPAdaptive Organic Particle
6
CONFIDENTIAL
Typical Dishing Results for PC606 (100 um lines)
~ 35 sec over-polishing under 1 psi, 95/85 rpm, 200 ml/min polishing condition
Baseline slurry PC606x21a Baseline slurry PC606x21b
Dishing of Cu Patterned Wafer
(1 psi, ~ 35 sec Over-Polishing)
0
100
200
300
400
500
600
3 (Middle) 4 5 (Center)
Die #
Dis
hin
g (
A) 100_100 Line
10_10
9_1
100_100 Pad
Dishing of Cu Patterned Wafer
(1 psi, ~ 35 sec Over-Polishing)
0
100
200
300
400
500
600
2 3 (Middle) 4 5 (Center)
Die #
Dis
hin
g (
A) 100_100 Line
10_10
9_1
100_100 Pad
7
Low Erosion on 9x1 Features shown by Profilometry TracesPark System AFM Profilometer Scan
Die#2 9_1 Feature Die#3 (middle) 9_1 Feature
8
Matching Surface Chemistry Increased efficiency of material removal
More effectiveLess effective
Activating / Passivating film•Generated in-situ
•To be removed
9
BASF TSV Cu CMP Slurry Defy Dishing Trend Predicted by
Polishing Rates for Conventional Slurry
0
200
400
600
800
1000
1200
1400
1600
1800
2000
0 5000 10000 15000 20000 25000 30000 35000 40000
MRR (A/min)
Dis
hin
g 1
00/1
00 u
m (
A)
BASF PC501
for TSV
Polishing rate vs dishing valuefor conventional slurry
10
Advanced BASF Barrier SlurryMaximize removal rate with minimal solids content
0
2
4
6
8
10
12
14
16
0 1 2 3 4 5 6 7
Abrasive (%)
Rel. Ta MRR
Rel. Cu MRR
Rel. BD MRR
Product Generations
Abrasive content significantly reduced
Key performance characteristics retained
Benefits for the customers:
1. Lower defects
2. Lower COO
3. Lower burden on filters4. Simpler waste treatment
0.25 micron line array after barrier polish
Minimal dishing and erosion
No EOE (“tiger teeth / fangs”)
11
BASF Planapur STI Products
Si Wafer
Pad oxide
Stopping Layer
Step height (P1)
SiN (P2A)
PolySi (P2B)
PS5545P2B
PS5010P2A
PS5600P1
Slurry CodeProcess
12
PS5600 (P1) – High RR STI Bulk100 x 100 line
0
1000
2000
3000
4000
5000
3159 A
Th
ickn
ess (
in a
ng
str
om
s)
Time (in sec)
3.5 psi
5 psi
0 60
4947 A
New
BASF particle
13
Copper Surface Oxidization/Passivation
Bulk metallic copper
Oxidized copper rich in
Cu (I) and Cu (II) ions
Copper ions diffuseinto aqueous phase
a
b
c
d
Dense passivating film
Copper ions diffusionare enhanced
Bulk metallic copper
Oxidized copper rich in
Cu (I) and Cu (II) ions
Copper ions diffuseinto aqueous phase
a
b
c
d
Dense passivating film
Copper ions diffusionare enhanced
Cu (I/II)
H2O
Cu (I/II)Cu (I/II).L2Cu (I/II).L2
14
15
Effect of Cu Ion on Water T1
0 500 1000 1500 2000
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
T1 (
se
co
nd
)
Concentration of copper ions (ppm)
0 100 200 300 400 500
0
1
2
3
4
5
0 500 1000 1500 2000
0
2
4
6
8
10
12
14
16
18
20
Concentration of copper ions (ppm)
1/T
1(s
ec-1
)
Concentration of copper ions (ppm)
y=0.0094x+0.2429
R=0.99941
1/T
1 (se
c-1)
y=0.00855x+0.3582
R=0.99965
16
0.0 0.1 0.2 0.3 0.4 0.5 0.60.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
T1
(secon
d)
Weight percent (%)
Film forming
None film
forming
Why induction period?
Classification of Complexing Agent
Cu (I/II).L2
Cu (I/II).Ln
17
Effect of Silica on BTA-Cu Complex
0 3 6 9 12 15
1.8
2.0
2.2
2.4
2.6
2.8
3.0
T1 (
se
cco
nd
)
BTA concentration (mM)
T1 values for water proton of 34 ppm Copper ions dependence on BTA concentration:
(■) in the presence of 0.2%N85 (●)without silica
Without silica
With silica
18
Reaction Between Cupric Ions and BTA
0.0 0.1 0.2 0.3 0.4 0.5 0.62
3
4
5
6
7
Water
Water+34 ppm Cu2+
Water+250ppm Cu2+
pH
BTA (wt %)
19
Reaction Between Glycine and BTA
0.0 0.1 0.2 0.3 0.4 0.5 0.62
3
4
5
6
7
8
pH
Glycine (wt %)
Water
Water+34 ppm Cu2+
Water+250ppm Cu2+
20
BTA Competes with Glycine for Cupric
0.0 0.1 0.2 0.3 0.4 0.5 0.63.2
3.4
3.6
3.8
4.0
4.2
4.4
pH
BTA (wt %)
No Cu
With Cu
Contains
0.6% Glycine
21
22
Particle size of samples containing varying amount of BTA and cupric ions
(■■■■ for 34 ppm and ●●●● for 250 ppm)
0.0 0.1 0.2 0.3 0.4 0.5 0.6
4
8
12
16
20
24
28
32P
art
icle
siz
e (
nm
)
Concentration of BTA (wt %)
23
TEM images of samples containing 0.2% BTA and varying amount of cupric ions
(left: 34 ppm and right: 250 ppm).
24
TEM images of samples collected from the wafer surfaces after the exposure to a solution containing hydrogen peroxide, glycine, and BTA (left) and a solution containing hydrogen peroxide and
BTA (right).
25
Summary
� BASF CMP slurry development setup
� Strong global R&D organization
� Local presence to support our customers
� Significant progress made in 2008/2009
� Innovative particles for copper slurries
– Functionality and morphology design
� Progress in barrier slurries
– Lower COO and defect level
� Polishing debris management for STI
– Lower defect
� Fundamental understanding of CMP
– Important component in slurry and R&D team development
26
Acknowledgment
� BASF (Germany)� Dr. Klemens Mathauer
� Dr. Michael Lauter� Dr. Mario Brands
� Dr. Vijay Raman
� Dr. Claus Poppe
� Mr. Yongqing Lan� Mr. Roland Lange� Ms. Elisabeth Seltzer
� Mr. Kennith Rushing� BASF (Asia)
� Dr. Charles Lin
� Mr. Kevin Teo (USA)
� Mr. JJ Chu� Mr. William Chiu� Mr. Daniel Shen� Mr. Robert Lo
� STLN/Clarkson University (USA)� Dr. Changxue Wang� Professor S.V. Babu
� Mr. Shyam Venkataraman� Mr. Paul Vendadi
� Mr. Ke Wang
� Mr. Harvey Pinder� Dr. Valli Ramji� Mr. Jeff Yu
� ISIT (Germany)
� Professor G. Zwicker
� Sun Yat-sen University (China)
� Professor Menglian Gong
� Ms. Yan Li