dry removal inflections in advanced memory devices...march 5, 2013 applied materials confidential r...
TRANSCRIPT
SILICON SYSTEMS GROUP
Dry Removal Inflections in Advanced
Memory Devices
Ajay Bhatnagar, Ph.D.
Global Product Management
Selective Removal Products
March 5, 2013
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
Outline
The Need for dry removal technologies in memory
What is causing pattern collapse
Parameters governing isotropic removal
Remote plasma sublimative removal technology
What’s next?
Summary
2
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
Pattern Collapse in Flash Memory
3
Aspect Ratios increasing at
exponential rate beyond 2x
Stiction Forces after wet/dry are
sufficient to cause STI Si Floating
Gate Structures to collapse
Ogawa Yoshihiro, TSB, Sept. 18, 2012 UCPSS
Ogawa Yoshihiro, TSB, Sept. 18, 2012 UCPSS
Before RIE post Wet Clean After Wet Cleaning
Ability to clean STI structures without pattern collapse is critical for F<2x
and D<2x technology nodes
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
What is Causing Pattern Collapse?
d is the deformation
s = surface tension
q = contact angle between the liquid & pattern
d = distance between the patterns,
H = height of the pattern,
E = elastic modulus
L =width of the pattern lines.
As feature sizes shrink: d, L ↓, H↑
As customers adopt lower k dielectrics, E ↓
Wets working to lower surface tension, s and contact angle, q
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
The Need for Dry Removal Being driven by
– 1) Pattern Collapse
– 2) Defectivity with existing wet benches
3) Inadequate selectivity/removal control with wet solutions
Aspect Ratios↑ Thermal Budgets ↓ driven by gate oxidation
STI: HDP (90) HARP (6x-4x) FCVD/SOD (3x…)
ThermalOxide
HDPOxide
HARPOxide
EternaFCVD(PMD)
Remote Plasma(Removal Rate/TOX) 1 1.03 1.05 1.03
Wet (WERR) 1 1.2 5.4 7
012345678
WER
R o
r R
R/T
OX
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
Remote Plasma Process
1. Echant Generation (Remote Plasma)
For Oxide
For Nitride
NF3+NH3 → NH4F + NH4F.HF
NF3 + H2 → HF + NH4F
NH4F + SiO2 → (NH4)2SiF6 + H2O
NH4F.HF + Si3N4 → (NH4)2SiF6 + H2O
2. Reaction to form By-Product
HF + Si3N4 → (NH4)2SiF6
NH4F + SiO2 → (NH4)2SiF6 + H2O RMS: 8.8nm
(NH4)2SiF6 (solid) → SiF4(g) + NH3(g) +HF(g)
3. Byproduct Sublimation
RMS: 0.3nm
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
Remote Plasma Mechanism
Solid By-products
Oxide
Si
(NH4)2SiF6.H2O
NH4F NH4+ + F-
NH4FHF NH4+ + HF2
- Diffusion through solid
of ionic species
Adsorption
Desorption/Sublimation Reactants and
Dissociated Species
SiO2 + F-/ HF2- SiF62- + H2O
Etching Reaction
at Interface
Removal Rate = Function of 3 Factors
Adsorption – Desorption ; Diffusivity in Solid (HF2-, F-, SiF6--) ;
Surface Reaction Rate
7
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP 8
Remote Plasma Removal Applications Floating Gate STI/ ILD Recess
Surface Post CMP Oxide Recess
Si
FG Ox
Uniform precision recess of ILD oxide in Flash
without opening ILD air gap
ST
I R
ecess
ILD
Recess
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
What’s Next? Can we use this concept for other material systems?
Oxid
e
POLY
Oxid
e
POLY
Oxid
e
400A Poly Removal
Oxid
e
POLY
Oxid
e
Elimination of Physical Etch leads to Pure Isotropic Removal
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP 10
Remote Plasma Removal Applications Floating Gate Direct Trimming
Surface Post CMP Oxide Recess Direct Trim of Silicon
FG shaping can enable IPD and
CG insertion and reduce IPD
scaling requirements
Floating Gate Shaping improves control-gate coupling
ratio by enabling control-gate-poly wrap-around
At 2X node, Inter-FG space is
insufficient for 13nm thick IPD +
8nm CG insertion
Tox
FG
Tox
FG
Tox
FG
Tox
FG
Tox
FG
Tox
FG
Tox
FG24nm
24nm
13nm
12nm
11nm
CG poly
Tox
FG
Tox
FG
Tox
FG
Tox
FG
Tox
FG
Tox
FG
Tox
FG
24nm 24nm
CG poly
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
Mesh SiN
Anchoring SiN
TiN Cylinder
Remote Plasma Removal Application Advanced DRAM Mold Silicon Removal
11
Pre-Structure Desired Result
Removal of large amount of silicon through small access holes on the
mesh SiN in a multi-selective environment
Peri
Oxide
Mold
Si
1.5
mm
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
Remote Plasma Removal Application Nitride Removal
0
100
200
300
400
500
600
PE Nitride PR Oxide
Re
mo
va
l A
mo
un
ts (
A)
Replacement of Hot Phos in
Patterning Applications
Increased interest in demos
with PR
Selectivity to Oxide and PR
demonstrated
Nitride Hardmask removal
High selectivity to STI and
Pad Oxide
Removed Material Binary System Best Selectivity
Nitride
(LP SiN: 200A)
LPCVD SiN : HDP Oxide 195:1 to 1:1
Tensile Nitride : HDP
Oxide
560:1
Comp. Nitride : HDP Oxide 430:1
Applied Materials Confidential
R 140
G 140
B 140
R 220
G 220
B 220
R 69
G 153
B 195
R 254
G 203
B 0
R 255
G 121
B 1
R 234
G 40
B 57
R 155
G 238
B 255
R 146
G 212
B 0
R 75
G 75
B 75
R 6
G 30
B 60
SILICON SYSTEMS GROUP
Summary
13
Pattern collapse with wet chemistries will become a critical issue in
advanced memory devices with increasing aspect ratios and softer
dielectrics
The transition to dry removal technologies has already occurred with
remote plasma chemical etch replacing several DHF steps in FEOL
memory flows
– Driven by precision removal capabilities and control of dry techniques
Dry removal reactors that can simulate wet chemistries to etch with
similar selectivities and without pattern collapse will be critical for
advanced memory devices
