ALD MATERIALS INTEGRATION CHALLENGES

GLEN WILK

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OUTLINE

› Industry Trends for Materials and Architectures

› Examples of materials innovations• High-­k and metal gate

• Patterning materials

• New spacer materials

• Low thermal budget processes

› Needs from Chemical Suppliers

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INDUSTRY TRENDS

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ARCHITECTURAL INNOVATIONS: MOORE’S LAW ENABLERS

Planar FG NAND

Charge trap NAND

Bipolar

Planar CMOS

Stacked capacitor

FinFET

TSV’s

Planar DRAM

3D NAND

Cross-­point

Dual Damascene

Multilevel interconnect

Spacer Defined Patterning

Airgaps

e-­DRAM

e-­RRAM

Pillar capacitor

SoC

H-­nanowires

V-­nanowires

TFET

Self-­aligned via’sSOI

Stacked CMOS

Hetero-­semi stacksSTT RAMTrench

capacitor

RCAT

~1980 ~2000 ~2020

Buried WL

Cylinder capacitor

FDSOI

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INDUSTRY TRENDS IN LOGIC

Higher Capacitance, Lower Leakage Higher Mobility, Lower Resistance

Smaller Feature SizesLess Cross Talk, Faster Interconnect

(Porous) Low-­k Materials

Improved Metals

High-­k and Metal Gates

DRAM, RF, decoupling capacitors

Strain and new Channel MaterialsNew metal contacts

-­EUV delays led to more double patterning (SDDP/SDQP) -­EUV will enable many new materials

ASM Proprietary and Confidential Information

© Chipworks

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INDUSTRY TRENDS IN MEMORY

VNAND high-­mobility channels

Vertical NANDDRAM cell Staircase

New Materials:ALD III-­VConductive oxides

Requirements:Thickness<10nmAR>50Thermal stab 800CConformality: 95%

New Materials:Low R metals

Requirements:R<100uOhm*cmFluorine free

New materials:High WF metal for TE and HK in BOCT layersRequirements: Thickness<5nmMG WF>4.8eV

New Materials:Selective ALD in staircaseALD a-­C protective fill layerResist hardening

1st Litho

Sel. Tr.

.

Sel. Tr.

2nd Litho

Source: Chipworks

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MATERIALS INNOVATIONS

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NEW MATERIALS: MOORE’S LAW ENABLERS

sSOI/GeOIGe ILIII-­‐V IL

* GaNInSb

InGaAsGeSTORu

Other PM'sEUV

Other PM'sEUV

Co CoSi(C)P Si(C)PFDSOI FDSOISiC SiCAir AirSiCO SiCOLaO LaOLT SiO LT SiO

SiCN SiCN SiCNTiAlC MG TiAlC MG TiAlC MG

ZrO ZrO ZrOHf(Si)O Hf(Si)O Hf(Si)OAlO AlO AlOpSiOC pSiOC pSiOCSOI SOI SOI

SiGe(B) SiGe(B) SiGe(B)TaO TaO TaO TaOSOG SOG SOG SOGSiOC SiOC SiOC SiOC

Ta/TaN Ta/TaN Ta/TaN Ta/TaNCu Cu Cu CuSiOF SiOF SiOF SiOF

TiSi TiSi TiSi TiSi TiSiPtSi PtSi PtSi PtSi PtSi

TiW TiW TiW/TiN TiN TiN TiNWSi, MoSi WSi, W WSi, W W W W

BPSG BPSG BPSG BPSG BPSG BPSG BPSGAl Al Al Al Al Al Al Al

SiO, SiN SiO, SiN SiO, SiN SiO, SiN SiO, SiN SiO, SiN SiO, SiN SiO, SiNSi Si Si Si Si Si Si Si

1960 1970 1980 1990 2000 2010 2015 2020(*)

(*): Projection

Patterning RelatedBEOLFEOLStarting Materials

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THERMAL ALD SOLUTIONS CRITICAL FOR 3D STRUCTURES

› Move to 3D devices necessitates the use of pure thermal ALD techniques

› Lower thermal budgets for ALD and PEALD

Thermal ALD Plasma ALD

Directional nature of reactants results in non-­uniform composition

Step coverage limited (especially in re-­entrant structures)

Near perfect step coverage in deep and re-­entrant structures

Stoichiometric film regardless of directionality

Source: SemiEngineering

Source: IMEC

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PROCESS INNOVATIONS: MOORE’S LAW ENABLERS

› Thermal and plasma-­enhanced ALD are materials enablers: l High-­k capacitor

l High-­k gate dielectric

l Metal gate

l Metal Nitrides (HfN)

l Low-­T oxide

l Low-­T nitride… Made by ASM

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PROCESS INNOVATIONS: ALD AND PEALD

› Atomic Layer Deposition separates reactive precursors in time (or space), and grows materials one ‘atomic’ layer at a timel Superb control of uniformity, conformality, quality, and composition over any topography

l Plasma Enhanced ALD provides high quality materials at lower temperatures

l Need many etch selective materials with wide range of film properties and compositions

› ALD and PEALD are architecture enablers: High Aspect Ratio structures, FinFET, double patterning, VNAND,…

Right: NY Times 2011;; http://electroiq.com/chipworks_real_chips_blog/2014/08/04/

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METAL FOR VNAND WL FOR VERTICAL & LATERAL PITCH SCALING

› To enable vertical scaling of word linel Development of ALD TiN with fast-­closing layer < 15A

l Development of F-­free ALD processes

l New precursors

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CRITICAL ALD SUPPLY CHAIN COMPONENTS

Fundamental Capability

Process Performance Productivity Integrated

ProcessFinal Product Capability

Precursors

Precursor Delivery, Valves and Vessels

Reactors

Fab facilities,pumps & abatement

High productivity tools

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WHAT’S NEXT IN PROCESS INNOVATIONS?

› The surface sensitivity of ALD and CVD may be ideal to create selective deposition l Many potential applications exist in memory, logic, interconnect, and patterningl Building templated self-­aligned structures: reduction of overlay requirements

› Strong need for many variations of selective ALD: Metal on Metal, Dielectric on Dielectric, etc.› Reversing the reaction to highly selective Atomic Layer Etching

Si

H H H H H H

Cu

OH O OH OHO O

Cu

CH3

Restored Low-­k

O CH3 CH3 OCH3

OH O OH OH O

Damaged low-­k

OH

Si

OH OH OH OH OH OHNat. Oxide

Si3N4

NH2 NH NH2 NH2N NH

TiN

NH2 NH OH NH2N N

SiO2

O O OOHOH OH

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LOW THERMAL BUDGET PROCESSES

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HIGH MOBILITY CHANNEL MATERIALS

› Voltage scaling requires high mobility channel materials with proper bandgap› Introduction will probably be simultaneous with architecture change to nanowires› Epitaxy and ALD will be enabling deposition technologies

2011

~2021

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NEW CHANNEL MATERIALS DRIVING LOWER THERMAL BUDGET

› Thermal budget is squeezed in the middlel Ge melting point is 940C versus 1412C for

Si;; many more process steps

l Need for low temperature high quality

materials

› Example: SiN for gate spacerl Batch LPCVD: DCS + NH3 @ 650~750C

l Batch ALD: DCS + NH3 @ 500~650C

l Single wafer PEALD: novel precursors @

350 to 550C

Si: 1412C

Ge: 940C

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NEEDS FROM CHEMICAL SUPPLIERS

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HOW CHEMICAL SUPPLIERS CAN HELP

› Novel materialsl Precursors for low-­resistivity metals, ternary films with incorporation from the precursor

as part of deposition process

l Highly reactive precursors that can enable fast film closure

› Precursors with high reactivity at low temperaturel New materials are driving FEOL processes toward 400C

l Enabling low-­T processes for existing materials like SiO and SiN

› Chemicals that do not easily decompose even with long residence times in reactors for high-­aspect ratio structuresl Solid precursors, lower-­volatility liquids

› Enable faster development cycle by doing more in-­house pre-­screeningl Representative reactors and structures to show upfront feasibility for step coverage,

utilization, efficiency of incorporation

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CONCLUSION AND SUMMARY

›Moore’s Law is increasingly a materials playl Enabling materials such as HfO2, ZrO2, Si:Ge, Si:P, Co, …

l Enabling processes for existing materials like LT SiO and SiN

› New device architectures and EUV will drive stronger need for flexible chemistries and film properties

› Selective deposition in various combinations of surface and film type will be required

›Many opportunities for enabling materials solutions with innovative chemistries

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ACKNOWLEDGEMENTS

Thanks for your attention!

›Thanks to Ivo Raaijmakers, Bob Hollands, Bert Jongbloed, Jan Willem Maes, John Cossins, Hessel Sprey, and many others for providing material, and their help in preparing, for this presentation