TIMARIS

L
L
Techniki nanoszenia
Lecture 9
Nano-Scale Sputter Deposition of Thin Films and
Film Stacks for Data Storage Applications
W. Maass, B. Ocker, J. Langer
Ultrasmooth Workshop – Kraków, July 4-6, 2007
What are we talking about ?
Outline
¾ The challenge: Industrial deposition of thin films and film
stacks for magnetic and magneto – electronic
applications
¾ General deposition concepts
¾ Sputter deposition (PVD) technologies
¾ Linear Dynamic Deposition – a successful PVD
technology
Layer stack of a MRAM Cell
Capping Layer (Ta)
Free Layer 1 (CoFe)
Barriere MgO, Al2O3
AAF Spacer (Ru)
Free Layer 2 (NiFe)
Pinned Layer 2 (Co60Fe40)
Pinned Layer 1 (CoFe)
Antiferromagnet (PtMn, IrMn)
5-15 nm
2-3 nm
0.8-1.5 nm
0.5-2 nm
2-3 nm
0.8-0.9 nm
2-3 nm
10-25 nm
Seed Layer 2 (NiFe)
2-5 nm
Seed Layer 1 (Ta, NiFeCr)
2-5 nm
Contact (Cu, Al)
Buffer (Ta)
8 different materials (or more) in the TMR layer stack !
40-60 nm
2-5 nm
Layer stack of a MRAM Cell
Capping Layer (Ta)
Free Layer 1 (CoFe)
Free Layer 2 (NiFe)
Uniformity on
Pinned Layer 2 (Co
large
Wafers
AAF Spacer (Ru)
Barriere MgO, Al2O3
60Fe40)
Pinned Layer 1 (CoFe)
Antiferromagnet (PtMn, IrMn)
5-15 nm
2-3 nm
0.8-1.5 nm
0.5-2 nm
2-3 nm
0.8-0.9 nm
2-3 nm
10-25 nm
Seed Layer 2 (NiFe)
2-5 nm
Seed Layer 1 (Ta, NiFeCr)
2-5 nm
Contact (Cu, Al)
Buffer (Ta)
8 different materials (or more) in the TMR layer stack !
40-60 nm
2-5 nm
Layer stack of a MRAM Cell
5-15 nm
Capping Layer (Ta)
Free Layer 1 (CoFe)
Free Layer 2 (NiFe)
Uniformity on
Pinned Layer 2 (Co
large
Wafers
AAF Spacer (Ru)
Barriere MgO, Al2O3
60Fe40)
Interface
Quality
Pinned Layer 1 (CoFe)
Antiferromagnet (PtMn, IrMn)
2-3 nm
0.8-1.5 nm
0.5-2 nm
2-3 nm
0.8-0.9 nm
2-3 nm
10-25 nm
Seed Layer 2 (NiFe)
2-5 nm
Seed Layer 1 (Ta, NiFeCr)
2-5 nm
Contact (Cu, Al)
Buffer (Ta)
8 different materials (or more) in the TMR layer stack !
40-60 nm
2-5 nm
Layer stack of a MRAM Cell
5-15 nm
Capping Layer (Ta)
Free Layer 1 (CoFe)
Free Layer 2 (NiFe)
Uniformity on
Pinned Layer 2 (Co
large
Wafers
AAF Spacer (Ru)
Barriere MgO, Al2O3
60Fe40)
Interface
Quality
Pinned Layer 1 (CoFe)
Antiferromagnet (PtMn, IrMn)
2-3 nm
0.8-1.5 nm
0.5-2 nm
2-3 nm
0.8-0.9 nm
2-3 nm
10-25 nm
Seed Layer 2 (NiFe)
2-5 nm
Seed Layer 1 (Ta, NiFeCr)
2-5 nm
Contact (Cu, Al)
Repeatability
Buffer (Ta)
8 different materials (or more) in the TMR layer stack !
40-60 nm
2-5 nm
Layer stack of a MRAM Cell
5-15 nm
Capping Layer (Ta)
Free Layer 1 (CoFe)
Free Layer 2 (NiFe)
Uniformity on
Pinned Layer 2 (Co
large
Wafers
AAF Spacer (Ru)
Barriere MgO, Al2O3
60Fe40)
Interface
Quality
Pinned Layer 1 (CoFe)
Antiferromagnet (PtMn, IrMn)
2-3 nm
0.8-1.5 nm
0.5-2 nm
2-3 nm
0.8-0.9 nm
2-3 nm
10-25 nm
Seed Layer 2 (NiFe)
2-5 nm
Seed Layer 1 (Ta, NiFeCr)
2-5 nm
Contact (Cu, Al)
Repeatability
40-60 nm
Cost Performance
(CoO)
Buffer (Ta)
8 different materials (or more) in the TMR layer stack !
2-5 nm
Layer stack of a MRAM Cell
5-15 nm
Capping Layer (Ta)
Free Layer 1 (CoFe)
Free Layer 2 (NiFe)
Uniformity on
Pinned Layer 2 (Co Fe )
large
Wafers
AAF Spacer (Ru)
and
more
Pinned….
Layer
1 (CoFe)
Barriere MgO, Al2O3
60
Interface
Quality
40
Antiferromagnet (PtMn, IrMn)
…. and more
10-25 nm
Seed Layer 2 (NiFe)
2-5 nm
…. and more
Seed Layer 1 (Ta, NiFeCr)
Contact (Cu, Al)
Repeatability
2-3 nm
0.8-1.5 nm
0.5-2 nm
2-3 nm
0.8-0.9 nm
2-3 nm
2-5 nm
40-60 nm
Cost Performance
(CoO)
Buffer (Ta)
8 different materials (or more) in the TMR layer stack !
2-5 nm
Non – AFC Multilayer for TFH
Cap
High magnetic Moment Bs
Interface quality
Magnetic EA
alignment
CoFe 25
NiFe
Al2O3
Hce, Hch, Hk, Br
Uniformity on large wafers
Repeatability
CoFe 25
Cost of Ownership
Seed
NiFe 1.5/7x[ FeCo30 25/Al2O3 0.5/NiFe 1.0]/FeCo30 25/NiCr 3 Æ
200nm FeCo
(5% N2 during FeCo deposition)
Vacuum deposition technologies
What do we use?
¾ Evaporation
¾ CVD (Chemical Vapor Deposition)
¾ ALD (Atomic Layer deposition)
¾ IBD (Ion Beam Deposition)
¾ PVD (Physical Vapor Deposition)
Vacuum deposition technologies: PVD
Permanent Magnets Æ Magnetron
N
S
S
Cooling
Target = Cathode
Plasma
Anode
S
Plasma
Substrate
DC, RF
N
Aligning Magnetic Field (AMF)
Ar (Kr) Ions
Electrons
Ar (Kr) of low pressure ( < 10-2 mbar)
Anode
Vacuum deposition technologies: PVD
Static Deposition by circular cathode
Permanent Magnets (cross section:
)
S
N
Target
Distance
Substrate
Pro’s:
Con’s:
• Efficient deposition
• Poor thickness uniformity
• Simple technology
• Not good for very thin films (1 – 2 nm)
• Not useable for ferromagnetic films Æ
Leakage field
S
Vacuum deposition technologies: PVD
Quasi - Static Deposition by circular cathode
Cathode: Spinning Magnets
Example: Anelva C7100
Features:
Uniformity by (fast) substrate
rotation
Cathode – substrate material flow
with angle of incidence and offset
Target
Substrate
Distance (TSD)
offset
Spinning magnetron
magnets for target utilization
C7100: 4, 5 or 8 (small) cathodes /
chamber; up to four chambers /
tool, base pressure 5*10-9 mbar
C7100:
up to 200mm wafer
C7100EX: up to 300mm wafer
Spinning substrate &
Spinning AMF
Pro’s:
• Small targets (pro for R&D)
• Co-Sputter feasible
Vacuum deposition technologies: PVD
Quasi - Static Deposition by circular cathode
Example: Anelva C7100
Cathode: Spinning Magnets
Con’s:
• For magnetic alignment: rotating
magnetic filed required Æ
interference with plasma
• Magnetron leakage field Æ
interference with substrate
Target
Substrate
Distance (TSD)
offset
• Large TSD req’d !!!
• Very poor coating efficiency
Spinning substrate &
• Small targets Æ Short target life
time !!
Spinning AMF
• High Cost of Ownership (CoO)
• Fast rotating parts in vacuum
• Complicated mechanics
Vacuum deposition technologies: PVD
Dynamic Deposition
Example: Leybold, BPS, Unaxis Æ Corona; Emerald I, II; Cyberite PVD
Target = Cathode
Pro’s:
• Simple cathode design
Substrate
• Proven technology
• Batch load good for throughput
Turn - table
Con’s:
• Poor uniformity, but “Aperture shaper”
Features:
Batch load possible
Corona/Emerald I: 4 cathodes,
max. 150mm wafer, 1*10-7 mbar
Emerald II: 6 cathodes,
max. 200mm wafer, 1*10-7 mbar
Cyberite PVD: 10 cathodes, no
batch load possible
max. 200mm wafer, 1*10-8 mbar
• Bad coating efficiency Æ CoO?
• For magnetic alignment Æ magnetic
field moving with wafer required Æ
TSD !!
• Magnetron leakage field Æ interference
with substrate Æ TSD!!
Vacuum deposition technologies: PVD
Dynamic Deposition Æ Variants
Example: Veeco Nexus, PVD-10P
Target = Cathode
Pro’s:
• Simple cathode design
Substrate
Turn - table
Features:
10 cathodes (PVD-10) or
12 cathodes (Nexus)
Tools for up to 200mm wafer
Base pressure: 5*10-9 mbar
Con’s:
• Uniformity by rotating & moving
substrate
• For magnetic alignment: rotating &
moving magnetic filed required Æ
interference with plasma Æ TSD !!
• Magnetron leakage field Æ
interference with substrate Æ TSD!!
• CoO ??
• Complicated mechanics, fast rotating
parts in vacuum
Vacuum deposition technologies: PVD
Linear Dynamic Deposition (LDD)
Example: Singulus TIMARIS
Pro’s:
Magnet Array
Wafer
•Leakage field of cathode parallel to wafer
travel direction:
Ideal symmetry for magnetic film
applications
-
•Stationary Aligning Magnetic Field
(AMF):
Sputter Target
AMF can be optimized with cathode
-
Deposition Area
Yoke
Yoke
Wafer Travel
Static DepRate
N
S
Vacuum deposition technologies: PVD
Linear Dynamic Deposition (LDD)
Example: Singulus TIMARIS
Pro’s:
Magnet Array
Wafer
•Short Target-Substrate Distance:
-
Good Coating Efficiency
•Thickness adjusted by wafer speed:
-
Tight control & repeatability
•No fast moving parts in vacuum
-
Sputter Target
Deposition Area
Wafer Travel
Static DepRate
Robust and reliable design
Vacuum deposition technologies: PVD
Linear Dynamic Deposition (LDD)
Example: Singulus TIMARIS
Features TIMARIS:
Magnet Array
Wafer
Thickness (and other materials) uniformity
obtained by cathode – substrate geometry
10 targets in one PVD chamber, max. two
10-PVD chambers / tool Æ high throughput
Other modules: Oxi, Soft-Etch
Sputter Target
Target Drum
Targets
Bridge tool: Wafer diameter 150mm, 200mm,
300mm
Ultra – High – Vacuum design
(5*10-9 mbar base pressure)
Robust and reliable mechanics
TIMARIS
300/200/150/100mm PVD Bridge System
A Proven Deposition Tool for
TFH, MRAM and other
Semiconductor Applications
TIMARIS: 20 years of Experience
In its history the NDT team has designed, built and run different
types of production tools (PVD, IBD, CVD) for
ƒ Thin Film Head Manufactering (e.g. Ferro – Magnetic films and film stacks)
ƒ Flat Panel Display (large area deposition)
ƒ Semiconductor (e.g. Metallization)
Business Summary
SINGULUS Nano Deposition Technologies
ƒ TIMARIS for MRAM, Magnetic
Read/Write head production and other
Semiconductor applications
ƒ PVD Bridge system: 300mm (12”),
200mm (8”) and 150mm (6”) capability
Installed Base until Q2/07
Business Unit:
¾ One system shipped to customer in Q4/06 for
Thin Film Head production
¾
Core Team now 27 people + approx. 10 to 15
additional workers (Singulus operations and non –
permanent)
¾
Clean Room:
¾ Two more systems shipped in Q1/07 for
MRAM production (1xUS, 1xEU)
¾ One additional system for Thin Film Head
production just shipped to the customer
¾
Order Backlog as of Q2/07
¾ One system for TFH production, to be
shipped to customer by Q1/08
¾
•
40 sqm class 1.000 (R&D)
•
160 sqm class 10.000 (Assembly)
Key Metrology:
•
CIPT – TMR Metrology (CAPRES)
•
MOKE
•
VSM
•
KLA – Tencor TBI
•
AFM
•
4PP Sheet Resistance Mapper (Ø300mm)
•
Spectral Ellipsometer
New R&D Tool with RF capability under installation in
Singulus Clean Room
TIMARIS: Production area (clean rooms)
TIMARIS: Photography
Multi Target Module
Top: Target Drum with 10
rectangular cathodes; Drum
design ensures easy
maintenance;
Bottom: Main part of the
chamber containing LDD
equipment
Oxidation Module
Low Energy Remote
Atomic Plasma Oxidation;
Natural Oxidation;
Soft Energy Surface
Treatment
Soft-Etch Module
(PreClean, Surface
Treatment)
Transport Module
(UHV wafer handler)
Cassette Module
(according to
Customer request)
Ultra – High – Vacuum Design:
Base Pressure ≤ 5*10-9 Torr (Deposition Chamber)
High Throughput (e.g. MRAM):
9 Wafer/Hour (1 Depo-Module), 18 Wafer/Hour (2 Depo-Module)
High Effective Up-time:
Maintenance friendly Design
Reliability:
Solid and well Engineered Design, no fast moving Parts
TIMARIS: Layout including cabinets
Typical Cluster Tool Configuration for 150 mm or 200mm wafer processing:
(TFH production, MRAM pilot production, R&D)
(15.7 ft)
(27.8 ft)
Configuration
can be modified
according to
customer
request.
Oxi-Module
TIMARIS: Layout
Typical Cluster Tool Configuration for fully equipped Tool:
(300mm wafer processing)
Standard UHV
Transport Module
incl. EFEM
1 x Oxi-Module
1 x Soft Etch, Surface
Treatment Module
2 x Vacuum load locks
(configuration can be
modified according to
customer request)
5.00 m (16.4 ft)
2 x Multi-TargetModules with 10
Targets each
5.50 m (18 ft)
TIMARIS: Thickness Uniformity
@ 200 mm, 6mm edge exclusion
200 mm data
@ 300 mm, 6mm edge exclusion
Al
Cu
NiFe
CoFe40
Ta
PtMn
Ru
IrMn
NiFeCr
0.23% (1σ)
0.43% (1σ)
0.66% (1σ)
0.77% (1σ)
0.51% (1σ)
0.34% (1σ)
0.50% (1σ)
0.59% (1σ)
0.80% (1σ)
Al
Cu
NiFe
CoFe
Ta
PtMn
Ru
IrMn
NiFeCr
0.16% (1σ)
0.42% (1σ)
0.36% (1σ)
0.22% (1σ)
0.41% (1σ)
0.24% (1σ)
0.17% (1σ)
0.18% (1σ)
0.24% (1σ)
300 mm data
TIMARIS: Thickness Control, Example GMR
As deposited GMR stack (no pinning):
Ta10/PtMn20/CoFe2/Ru(x)/CoFe2/Cu2.2/CoFe0.8/NiFe3.8/Ta5 (thickness in nm)
Effect of AF coupling
in the AAF structure:
CoFe2/Ru(x)/CoFe2
TIMARIS: CoFe Multilayer
Non – AFC Multilayer using Fe70Co30 :
250
NiFe 1.5/7x[ FeCo30 25/Al2O3 1.0/NiFe 1.0]/FeCo30 25/NiCr 3 Æ 200nm FeCo
200
Y - position [mm
(5% N2 during FeCo deposition)
150
100
50
50
100
150
X - position [mm]
Cap
Hce:
Hk:
Hch:
Mr/Ms:
3.0 Oe
99.2 Oe
3.8 Oe
4.0 %
CoFe 25
CoFe 25
Seed
200
250
TIMARIS: AFC coupled CoFe Double Layer
0.04
Magnetization [memu]
0.03
0.02
@Samplename:
3229
Seed/ 25CoFe/ 0.91Ru/ 25CoFe/ 5Ta
Hce
= 18.9 Oe
HAFC = 60.0 Oe
Cap
Hk*
= 155.3 Oe
Brh/Bs =
1.2 %
0.01
0.00
-0.01
-0.02
CoFe
-0.03
-0.04
-300
-200
-100
0
100
200
Ru
300
applied field [Oe]
Goal: zero remanence
CoFe
in EA and HA
Seed
Avoid over-write in
PMR
Seed/ 50CoFe/ 0.91Ru/ 50CoFe/ 5Ta
0.08
Magnetization [memu]
0.06
0.04
@Samplename:
3227
0.02
0.00
-0.02
-0.04
-0.06
-0.08
-300
-200
-100
0
applied field [Oe]
100
200
300
Hce
HAFC
Hk*
Brh/Bs
= 31.2 Oe
= 27.3 Oe
= 202.2 Oe
=
0.4 %
TIMARIS: Al2O3 - TMR vs. RA - Summary
TIMARIS: MgO – TMR - Summary
MgO – Barrier, TMR vs. RA:
TIMARIS: MgO – TMR, Summary
RF sputtered MgO – Barrier: TMR & RA vs. MgO Thickness:
(Comparison of different Target Vendors)
TIMARIS: Remote Plasma Oxidation uniformity
Improvement by grid optimization
Steps:
• Reduction of grid transparency (oxidation at higher power)
• Grid optimization using sheet resistance of Ta/Al-ox layers
• Final grid optimization using RA uniformity across wafer
TIMARIS: Oxidation Uniformity (Al2O3 – Barrier)
Measured by CIPT
TIMARIS: Repeatability (Al2O3 – Barrier)
Measured by MOKE
TIMARIS: MgO TMR Uniformity
Mg Sputtering + Oxidation
Mg content and MgO thickness
in plasma-oxidized Mg MTJ measured by XRF
MgO - thickness:
1.21nm, 1σ = 0.71%
Mg concentration in MgO:
50.48at%, 1σ = 0.45at%
49,70
1,190E4
49,86
100
1,194E4
100
50,02
1,201E4
50
50,34
50,50
0
50,66
50,82
-50
Y Axis Title
Y Axis Title
1,197E4
50,18
50
1,205E4
1,209E4
0
1,212E4
1,216E4
-50
50,98
1,220E4
51,14
-100
1,223E4
-100
51,30
-100
-50
0
X Axis Title
50
100
1,227E4
-100
-50
0
50
100
X Axis Title
XRF - etch / Ta 10 / PtMn64 0.5kW 150sccm 15 / CoFe20 2.4 / Ru 0.7 / CoFeB 2.8 / Mg 1.2 / ox 250W 10s 90sccm/ CoFeB 3.2 / Ta 10
TIMARIS: Repeatability (MgO – Barrier)
Mg remote plasma oxidation process
Stack: etch/seed/PtMn/CoFe/Ru/CoFeB20 /Mg1.1/ oxi /CoFe/NiFe/Ta/Ru
•
Deposit a cassette with 12 wafers
•
Anneal 1.5h @ 360°C with applied field 1T
•
Measure wafers from slot 1, 2, 5, 8, 12 with CIPT
•
Use a 49 point pattern with radius 75mm
•
Calculate the mean values of RA and TMR
WTW:
TMR:
RA
CIPT-measurement pattern for
49 points pattern
160
49 points
60.0
158
59.5
MR
RA
156
59.0
154
58.5
152
58.0
150
57.5
148
57.0
146
56.5
144
56.0
142
55.5
140
55.0
0
5
10
slot
15
RA [Ohm µm
Radius 75mm
TMR [%
notch
mean
149.7%
57.6Ohmµm²
1sigma
0.83%
0.63%
TIMARIS: MgO – TMR, Summary
Mg natural oxidation process 1*10-7 mbar
Stack: etch /buffer/PtMn/CoFe/Ru/CoFeB20/Mg/ natural oxidation
/CoFe/NiFe/Ta/CuN/Ru
80000
TMR
notch
8.970
60000
109.4
60000
40000
112.0
40000
9.299
20000
9.463
0
9.627
117.3
0
120.0
-20000
122.7
-40000
125.3
Y Axis Title
114.7
20000
Y Axis Title
80000
106.7
RA
notch
9.134
9.792
-20000
9.956
-40000
10.12
128.0
-60000
-60000
-80000
-80000 -60000 -40000 -20000
-80000
-80000 -60000 -40000 -20000
0
20000 40000 60000 80000
X Axis Title
TMR
Mean:
119.5%
1sigma: 5.0%
10.29
0
20000 40000 60000 80000
X Axis Title
RA
Mean:
9.52Ohmµm²
1sigma: 3.7%
Uniformity by
49-point pattern
TIMARIS: MgO – TMR, Summary
Breakdown Voltage for different MgO preparation techniques
(0.1 x 0.2 µm² devices)
TIMARIS: Next generation MRAM : CIS
Current Induced Switching or Spin-Torque-Transfer Switching
Stack (a,b) : Ta5/PtMn20/CoFe2/Ru0.8/
CoFeB2/MgO/CoFeB2.5/Ta8 (nm)
TMR ≈ 150%, RA ≈ 50 Ω*µm²
ic ≈ 1.1*106 A/cm²
Stack (c, d) : Ta5/PtMn30/CoFe3/Ru0.8/CoFeB2/
AlOx /CoFeB2.5/Ta5 (nm)
TMR ≈ 25%, RA ≈ 15 Ω*µm²
ic ≈ 4.3*106 A/cm²
Results obtained in cooperation with Grandis Inc., see e.g.
Zhitao Diao et al., Applied Physics Letters 87, 232502 (2005)
TIMARIS: Next generation MRAM : CIS
Current Induced Switching or Spin-Torque-Transfer Switching
Lowest Jc0 measured
(Grandis – Timaris)
TIMARIS: Unique Selling Points
TMR Wafer Production (MRAM and Thin Film Head)
„ High Throughput (incl. load and pre – clean):
-
Stack: Generic MRAM TMR: ≈ 9 wafer/h (1 MTM), ≈ 18 wafer/h (2 MTM)
Stack: Generic Low RA (MgO) TMR: ≈ 5 wafer/h (1 OM), ≈ 8 wafer/h (2
OM)
„ High Yield/Wafer by uniform TMR & Magnetic Properties
„ Tight Thickness Control of Ultra-Thin Films
-
Thinnest Film < 0.1 nm; Smallest Thickness Step: < 0.01 nm
„ Full flexibility regarding PVD – mode for all targets: DC, pulsed DC, RF
„ Longer production Cycles:
Approx. 6500 TMR wafers until target replacement & strip/clean
( approx. 4 weeks production 24h/7d)
„ Costs/Wafer:
-
6 – 7 US$/wafer (20nm PtMn deposition assumed)
-
Will save up to 1.0 Mio US$ compared with other TMR PVD tools
(18 wafer/h, 24h/7d production assumed)