Techniki nanoszenia Lecture 9 - Zespół Fizyki i...

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LTechniki nanoszeniaTechniki nanoszenia

Lecture Lecture 99

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 ?

OutlineThe challenge: Industrial deposition of thin films and film stacks for magnetic and magneto – electronic applications

General deposition concepts

Sputter deposition (PVD) technologies

Linear Dynamic Deposition – a successful PVD technology

Layer stack of a MRAM Cell

Pinned Layer 1 (CoFe)

Pinned Layer 2 (Co60Fe40)

Free Layer 2 (NiFe)

Capping Layer (Ta)

Antiferromagnet (PtMn, IrMn)

Seed Layer 2 (NiFe)

Contact (Cu, Al)

Buffer (Ta)

Seed Layer 1 (Ta, NiFeCr)

Free Layer 1 (CoFe)

AAF Spacer (Ru)Barriere MgO, Al2O3

2-5 nm

40-60 nm

2-5 nm

2-5 nm

10-25 nm

0.8-1.5 nm0.5-2 nm

2-3 nm

2-3 nm

2-3 nm 0.8-0.9 nm

5-15 nm

8 different materials (or more) in the TMR layer stack !




Free Layer 2 (NiFe)

Capping Layer (Ta)


Seed Layer 2 (NiFe)

Contact (Cu, Al)

Buffer (Ta)


Free Layer 1 (CoFe)Barriere MgO, Al2O3

AAF Spacer (Ru)

2-5 nm

40-60 nm

2-5 nm

2-5 nm

10-25 nm

0.8-1.5 nm0.5-2 nm

2-3 nm

2-3 nm

2-3 nm 0.8-0.9 nm

5-15 nm


Uniformity on large Wafers




Free Layer 2 (NiFe)

Capping Layer (Ta)


Seed Layer 2 (NiFe)

Contact (Cu, Al)

Buffer (Ta)



AAF Spacer (Ru)

2-5 nm

40-60 nm

2-5 nm

2-5 nm

10-25 nm

0.8-1.5 nm0.5-2 nm

2-3 nm

2-3 nm

2-3 nm 0.8-0.9 nm

5-15 nm



Interface Quality




Free Layer 2 (NiFe)

Capping Layer (Ta)


Seed Layer 2 (NiFe)

Contact (Cu, Al)

Buffer (Ta)



AAF Spacer (Ru)

2-5 nm

40-60 nm

2-5 nm

2-5 nm

10-25 nm

0.8-1.5 nm0.5-2 nm

2-3 nm

2-3 nm

2-3 nm 0.8-0.9 nm

5-15 nm



Interface Quality

Repeatability




Free Layer 2 (NiFe)

Capping Layer (Ta)


Seed Layer 2 (NiFe)

Contact (Cu, Al)

Buffer (Ta)



AAF Spacer (Ru)

2-5 nm

40-60 nm

2-5 nm

2-5 nm

10-25 nm

0.8-1.5 nm0.5-2 nm

2-3 nm

2-3 nm

2-3 nm 0.8-0.9 nm

5-15 nm



Interface Quality

Repeatability Cost Performance (CoO)




Free Layer 2 (NiFe)

Capping Layer (Ta)


Seed Layer 2 (NiFe)

Contact (Cu, Al)

Buffer (Ta)



AAF Spacer (Ru)

2-5 nm

40-60 nm

2-5 nm

2-5 nm

10-25 nm

0.8-1.5 nm0.5-2 nm

2-3 nm

2-3 nm

2-3 nm 0.8-0.9 nm

5-15 nm



Interface Quality

Repeatability Cost Performance (CoO)

…. and more…. and more…. and more

Non – AFC Multilayer for TFH

NiFe 1.5/7x[ FeCo30 25/Al2O3 0.5/NiFe 1.0]/FeCo30 25/NiCr 3 200nm FeCo(5% N2 during FeCo deposition)

Cap

CoFe 25

CoFe 25

Seed

High magnetic Moment Bs

Interface quality

Hce, Hch, Hk, Br

Uniformity on large wafers

Repeatability

Cost of OwnershipAl2O3NiFe

Magnetic EA alignment

Vacuum deposition technologies

What do we use?

Evaporation

CVD (Chemical Vapor Deposition)

ALD (Atomic Layer deposition)

IBD (Ion Beam Deposition)

PVD (Physical Vapor Deposition)

Vacuum deposition technologies: PVD

Target = Cathode

Substrate AnodeAnode

Ar (Kr) Ions

Electrons

DC, RFPlasma Plasma

Ar (Kr) of low pressure ( < 10-2 mbar)

Permanent Magnets Magnetron

S N S Cooling

S N

Aligning Magnetic Field (AMF)


Static Deposition by circular cathodePermanent Magnets (cross section: )

Pro’s:• Efficient deposition• Simple technology

Con’s:• Poor thickness uniformity• Not good for very thin films (1 – 2 nm)• Not useable for ferromagnetic films

Leakage field

Target

Substrate

Distance

S N S


Quasi - Static Deposition by circular cathodeExample: Anelva C7100

Pro’s:• Small targets (pro for R&D)• Co-Sputter feasible

Features:Uniformity by (fast) substrate rotationCathode – substrate material flow with angle of incidence and offsetSpinning magnetron magnets for target utilizationC7100: 4, 5 or 8 (small) cathodes / chamber; up to four chambers / tool, base pressure 5*10-9 mbarC7100: up to 200mm waferC7100EX: up to 300mm wafer

Cathode: Spinning Magnets

Spinning substrate &Spinning AMF

Target Substrate Distance (TSD)

offset


Con’s:• For magnetic alignment: rotating

magnetic filed required interference with plasma

• Magnetron leakage field interference with substrate

• Large TSD req’d !!!• Very poor coating efficiency• Small targets Short target life

time !!• High Cost of Ownership (CoO)• Fast rotating parts in vacuum• Complicated mechanics

Cathode: Spinning Magnets

Spinning substrate &Spinning AMF

Target Substrate Distance (TSD)

offset

Quasi - Static Deposition by circular cathodeExample: Anelva C7100


Dynamic DepositionExample: Leybold, BPS, Unaxis Corona; Emerald I, II; Cyberite PVD

Pro’s:• Simple cathode design• Proven technology• Batch load good for throughput

Con’s:• Poor uniformity, but “Aperture shaper”• Bad coating efficiency CoO?• For magnetic alignment magnetic

field moving with wafer required TSD !!

• Magnetron leakage field interference with substrate TSD!!

Target = Cathode

Turn - table

Substrate

Features:Batch load possibleCorona/Emerald I: 4 cathodes,

max. 150mm wafer, 1*10-7 mbarEmerald II: 6 cathodes,

max. 200mm wafer, 1*10-7 mbarCyberite PVD: 10 cathodes, no

batch load possiblemax. 200mm wafer, 1*10-8 mbar


Dynamic Deposition VariantsExample: Veeco Nexus, PVD-10P

Pro’s:• Simple cathode design

Con’s:• Uniformity by rotating & moving

substrate• For magnetic alignment: rotating &

moving magnetic filed required interference with plasma TSD !!

• Magnetron leakage field interference with substrate TSD!!

• CoO ??• Complicated mechanics, fast rotating

parts in vacuum

Target = Cathode

Turn - table

Substrate

Features:10 cathodes (PVD-10) or 12 cathodes (Nexus)Tools for up to 200mm wafer Base pressure: 5*10-9 mbar

Deposition Area

Wafer Travel

Static DepRate

Magnet Array

Sputter Target

Wafer

Pro’s:•Leakage field of cathode parallel to wafer travel direction:

- Ideal symmetry for magnetic film applications

•Stationary Aligning Magnetic Field (AMF):

- AMF can be optimized with cathode

Linear Dynamic Deposition (LDD)Example: Singulus TIMARIS


SN

Yoke Yoke

Deposition Area

Wafer Travel

Static DepRate

Magnet Array

Sputter Target

Wafer

Pro’s:•Short Target-Substrate Distance:

- Good Coating Efficiency•Thickness adjusted by wafer speed:

- Tight control & repeatability•No fast moving parts in vacuum

- Robust and reliable design



Magnet Array

Sputter Target

Wafer

Features TIMARIS:Thickness (and other materials) uniformity obtained by cathode – substrate geometry

10 targets in one PVD chamber, max. two 10-PVD chambers / tool high throughput

Other modules: Oxi, Soft-Etch

Bridge tool: Wafer diameter 150mm, 200mm, 300mm

Ultra – High – Vacuum design(5*10-9 mbar base pressure)

Robust and reliable mechanics



Target Drum Targets

A Proven Deposition Tool for TFH, MRAM and other Semiconductor Applications

300/200/150/100mm PVD Bridge System

TIMARIS: 20 years of Experience

In its history the NDT team has designed, built and run different types of production tools (PVD, IBD, CVD) forThin Film Head Manufactering (e.g. Ferro – Magnetic films and film stacks)Flat Panel Display (large area deposition)Semiconductor (e.g. Metallization)

TIMARIS

Business Summary SINGULUS Nano Deposition Technologies

Business Unit:Core Team now 27 people + approx. 10 to 15 additional workers (Singulus operations and non –permanent)

Clean Room:

• 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

Installed Base until Q2/07One system shipped to customer in Q4/06 for Thin Film Head production

Two more systems shipped in Q1/07 for MRAM production (1xUS, 1xEU)

One additional system for Thin Film Head production just shipped to the customer

Order Backlog as of Q2/07One system for TFH production, to be shipped to customer by Q1/08

TIMARIS for MRAM, Magnetic Read/Write head production and other Semiconductor applications

PVD Bridge system: 300mm (12”), 200mm (8”) and 150mm (6”) capability

TIMARIS: Production area (clean rooms)

TIMARIS: Photography

Multi Target ModuleTop: Target Drum with 10 rectangular cathodes; Drum design ensures easy maintenance;Bottom: Main part of the chamber containing LDD equipment

Transport Module(UHV wafer handler)

Oxidation ModuleLow Energy Remote Atomic Plasma Oxidation;Natural Oxidation;Soft Energy Surface Treatment

Soft-Etch Module(PreClean, Surface Treatment)

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 DesignReliability: 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)

Oxi-Module

(27.8 ft)

(15.

7 ft)

Configuration can be modified according to customer request.

Typical Cluster Tool Configuration for fully equipped Tool:(300mm wafer processing)

Standard UHV Transport Module incl. EFEM

2 x Multi-Target-Modules with 10 Targets each

1 x Oxi-Module1 x Soft Etch, Surface

Treatment Module2 x Vacuum load locks(configuration can be

modified according to customer request)

TIMARIS: Layout5.00 m

(16.4 ft)

5.50 m (18 ft)

TIMARIS: Thickness Uniformity

@ 200 mm, 6mm edge exclusionAl 0.16% (1σ)Cu 0.42% (1σ)NiFe 0.36% (1σ)CoFe 0.22% (1σ)Ta 0.41% (1σ)PtMn 0.24% (1σ) Ru 0.17% (1σ)IrMn 0.18% (1σ)NiFeCr 0.24% (1σ)

Al 0.23% (1σ)Cu 0.43% (1σ)NiFe 0.66% (1σ)CoFe40 0.77% (1σ)Ta 0.51% (1σ)PtMn 0.34% (1σ)Ru 0.50% (1σ)IrMn 0.59% (1σ)NiFeCr 0.80% (1σ)

@ 300 mm, 6mm edge exclusion300 mm data

200 mm data

As deposited GMR stack (no pinning):Ta10/PtMn20/CoFe2/Ru(x)/CoFe2/Cu2.2/CoFe0.8/NiFe3.8/Ta5 (thickness in nm)

TIMARIS: Thickness Control, Example GMR

Effect of AF coupling in the AAF structure:CoFe2/Ru(x)/CoFe2

50

100

150

200

250

50 100 150 200 250

X - position [mm]

Y - p

ositi

on [m

m

Non – AFC Multilayer using Fe70Co30 :

TIMARIS: CoFe Multilayer

NiFe 1.5/7x[ FeCo30 25/Al2O3 1.0/NiFe 1.0]/FeCo30 25/NiCr 3 200nm FeCo(5% N2 during FeCo deposition)

Hce: 3.0 OeHk: 99.2 OeHch: 3.8 OeMr/Ms: 4.0 %

Cap

CoFe 25

CoFe 25

Seed

Seed/ 25CoFe/ 0.91Ru/ 25CoFe/ 5TaHce = 18.9 OeHAFC = 60.0 OeHk* = 155.3 OeBrh/Bs = 1.2 %

TIMARIS: AFC coupled CoFe Double Layer

-0.04

-0.03

-0.02

-0.01

0.00

0.01

0.02

0.03

0.04

-300 -200 -100 0 100 200 300

applied field [Oe]

Mag

netiz

atio

n [m

emu]

@Samplename: 3229

Seed/ 50CoFe/ 0.91Ru/ 50CoFe/ 5TaHce = 31.2 OeHAFC = 27.3 OeHk* = 202.2 OeBrh/Bs = 0.4 %-0.08

-0.06

-0.04

-0.02

0.00

0.02

0.04

0.06

0.08

-300 -200 -100 0 100 200 300

applied field [Oe]

Mag

netiz

atio

n [m

emu] @Samplename:

3227

CoFe

Seed

CoFeRu

Cap

Goal: zero remanence in EA and HAAvoid over-write in PMR

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

Measured by CIPT

TIMARIS: Oxidation Uniformity (Al2O3 – Barrier)

TIMARIS: Repeatability (Al2O3 – Barrier)

Measured by MOKE

-100 -50 0 50 100

-100

-50

0

50

100

X Axis Title

Y A

xis

Title

49,70

49,86

50,02

50,18

50,34

50,50

50,66

50,82

50,98

51,14

51,30

Mg concentration in MgO: 50.48at%, 1σ = 0.45at%

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

-100 -50 0 50 100

-100

-50

0

50

100

X Axis Title

Y A

xis

Title

1,190E4

1,194E4

1,197E4

1,201E4

1,205E4

1,209E4

1,212E4

1,216E4

1,220E4

1,223E4

1,227E4

Mg content and MgO thickness in plasma-oxidized Mg MTJ measured by XRF

MgO - thickness: 1.21nm, 1σ = 0.71%

TIMARIS: MgO TMR Uniformity

Mg Sputtering + Oxidation

• 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

Stack: etch/seed/PtMn/CoFe/Ru/CoFeB20 /Mg1.1/ oxi /CoFe/NiFe/Ta/Ru

CIPT-measurement pattern for 49 points pattern

WTW: mean 1sigmaTMR: 149.7% 0.83%RA 57.6Ohmµm² 0.63%

Radius 75mm49 points

notch

140142144146148150152154156158160

0 5 10 15slot

TMR

[%

55.055.556.056.557.057.558.058.559.059.560.0

RA

[Ohm

µm

MRRA

TIMARIS: Repeatability (MgO – Barrier)

Mg remote plasma oxidation process

Stack: etch /buffer/PtMn/CoFe/Ru/CoFeB20/Mg/ natural oxidation /CoFe/NiFe/Ta/CuN/Ru

Mg natural oxidation process 1*10-7 mbar

TMRMean: 119.5%1sigma: 5.0%

RAMean: 9.52Ohmµm²1sigma: 3.7%

-80000 -60000 -40000 -20000 0 20000 40000 60000 80000-80000

-60000

-40000

-20000

0

20000

40000

60000

80000

X Axis Title

Y Ax

is T

itle

106.7

109.4

112.0

114.7

117.3

120.0

122.7

125.3

128.0

TMRnotch

-80000 -60000 -40000 -20000 0 20000 40000 60000 80000-80000

-60000

-40000

-20000

0

20000

40000

60000

80000

X Axis Title

Y A

xis

Title

8.970

9.134

9.299

9.463

9.627

9.792

9.956

10.12

10.29

RAnotch

Uniformity by49-point pattern


Breakdown Voltage for different MgO preparation techniques(0.1 x 0.2 µm² devices)


Current Induced Switching or Spin-Torque-Transfer Switching

TIMARIS: Next generation MRAM : CIS

Results obtained in cooperation with Grandis Inc., see e.g.Zhitao Diao et al., Applied Physics Letters 87, 232502 (2005)

Stack (c, d) : Ta5/PtMn30/CoFe3/Ru0.8/CoFeB2/AlOx /CoFeB2.5/Ta5 (nm)TMR ≈ 25%, RA ≈ 15 Ω*µm²ic ≈ 4.3*106 A/cm²

Stack (a,b) : Ta5/PtMn20/CoFe2/Ru0.8/CoFeB2/MgO/CoFeB2.5/Ta8 (nm)TMR ≈ 150%, RA ≈ 50 Ω*µm²ic ≈ 1.1*106 A/cm²

Current Induced Switching or Spin-Torque-Transfer Switching

TIMARIS: Next generation MRAM : CIS

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 PropertiesTight Thickness Control of Ultra-Thin Films

- Thinnest Film < 0.1 nm; Smallest Thickness Step: < 0.01 nmFull flexibility regarding PVD – mode for all targets: DC, pulsed DC, RFLonger 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)

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