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Patterning Challenges and Opportunities: Etch and · PDF filePatterning Challenges and Opportunities: Etch and Film Ying Zhang, Shahid Rauf, Ajay Ahatnagar, David Chu, Amulya Athayde,

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  • Y. Zhang et. al., Applied Materials

    Patterning Challenges and Opportunities:

    Etch and Film

    Ying Zhang, Shahid Rauf, Ajay Ahatnagar, David Chu, Amulya Athayde, and Terry Y. Lee

    Applied Materials, Inc.

    SEMICON, Taiwan 2016

    Sept. 07-09, 2016, Taipei, Taiwan

  • Y. Zhang et. al., Applied Materials

    Outline

    Advanced nodes pose challenges for patterning

    These challenges demand new film and etch/removal capabilities

    Atomic Level Deposition

    Atomic Level Etch and Removal

    Low electron temperature plasma etch

    Highly selective radical based removal

    Closing remarks

    2

  • Y. Zhang et. al., Applied Materials

    Advanced nodes pose

    challenges for patterning

  • Y. Zhang et. al., Applied Materials

    Lithography Technology

    248nm

    193nm

    193i

    Litho multiple exposure

    EUV

    Complementary Litho

    e.g., 193i + EUV

    Key challenge:

    Overlay

    EPE

    Materials Engineering

    Etch

    Film

    ALD

    Gapfill

    Selective removal

    ALE

    Selective deposition/growth

    Key advantage:

    Enable self-align schemes

    Atomic Level Controllability

    Patterning Technology Trend

    4

    Lithography Technology

    Materials Engineering

  • Y. Zhang et. al., Applied Materials

    SAxP Flows

    In SAxP pitch splitting flows

    1 litho step + many non-litho steps (film, etch, etc.)

    e.g.: SAQP:

    5

    Litho Etch ALD Etch ALD Etch

  • Y. Zhang et. al., Applied Materials

    CD/CDU/LER/LWR dominated by Litho, Etch and ALD

    In SAQP, there are 8 edges:

    Direct edge: = f (Litho CD/CDU/LER/LWR)

    S1 edge: = f (Litho and 1st spacer CD/CDU/LER/LWR)

    S2 edge: = f (1st and 2nd spacer CD/CDU/LER/LWR)

    S1/S2 edge: = f (1st , 1st spacer and 2nd spacer CD/CDU/LER/LWR)

    6

    Source: Schenker, Intel SPIE 2016

    To systematically reduce EPE:

    CD/CDU/LER/LWR of all edges at all steps

    need to be measured to trace down root

    causes

    Litho the key source of LER

    Etch/ALD the key for pitch walking

  • Y. Zhang et. al., Applied Materials

    These challenges demand new

    film and etch/removal

    capabilities - ALD

  • Y. Zhang et. al., Applied Materials Y. Zhang et. al., Applied Materials

    Conventional ALD

    Conventional ALD vs. OlympiaTM Reconfigures ALD

    8

    A

    B

    Off

    Off

    On

    On

    OlympiaTM ALD What is ALD?

    Divides CVD into two half-reactions

    Is self-limiting, producing uniform, conformal deposition

    Wafer travels continuously

    Spatially separated chemistries

    Chemistry-free zones isolate individual chemistries

    Precursor Precursor

    Wafer is stationary

    Alternating chemistries

    Purge separates chemistries

    Primary technology used today

    A B A B

    A B

  • Y. Zhang et. al., Applied Materials Y. Zhang et. al., Applied Materials

    Treatment

    X

    Modular Design for Atomic-Level Engineering

    Precursor Precursor Precursor

    20n

    m Silicon Oxide

    20n

    m Silicon Nitride

    20nm

    Titanium Oxide

    100nm

    Aluminum

    Oxide

    20nm

    Titanium Nitride

    Versatility Broadens Spectrum of

    Achievable ALD Materials without Compromising

    Productivity

    9

    A B Thermal

    B p

    A Plasma

    Enhanced

    ALD Mode Process Sequence

    Atomic-

    Layer

    Treatment

    X B A

    Conventional

    ALD

    OlympiaTM

    ALD

    Source: Applied Materials, Inc.

    http://www.clker.com/cliparts/c/o/y/d/d/p/chemistry-flask-md.pnghttp://www.clker.com/cliparts/c/o/y/d/d/p/chemistry-flask-md.png

  • Y. Zhang et. al., Applied Materials

    These challenges demand new

    film and etch/removal

    capabilities - Etch

  • Y. Zhang et. al., Applied Materials

    Plasma etching patterning trend

    Thin Layer Etching (TLE)

    Atomic Layer Etching (ALE)

    Complex pulsing technologies

    Advanced radical etching

    Low Te plasmas

    Neutral beam

    11

    RIE

    Mainstream plasma technologies

    Variety of CCP

    Variety of ICP

    ECR

    DSP/RP

    Add-ons

    Variety of RF pulsing technologies

    Mainstream plasma technologies

    Variety of CCP

    Variety of ICP

    ECR

    DSP/RP

    Add-ons

    Variety of RF pulsing technologies

  • Y. Zhang et. al., Applied Materials

    Basic Mechanisms of Reactive Ion Etching

    Ion-neutral reaction synergism

    One of the most important concepts of plasma-surface chemistry is the

    synergism of ion and neutral reactions

    Three key aspects of ion bombardment:

    Stimulate surface reactions

    Stimulate desorption or clear the surface of etch-inhibiting, nonvolatile residues

    Anisotropic or directional etching

    12

    Coburn and Winters, J. of App. Phys. 50. 3189-3196, 1979

    Ion Bombardment effects in Reactive Ion Etching

  • Y. Zhang et. al., Applied Materials

    Low electron temperature, Te, plasmas

    Intuitively, lower Te lower Vp lower ion energy lower damage

    ALE(?)

    How to control low ion energy, e.g., from

  • Y. Zhang et. al., Applied Materials

    Low Te Plasma Etch System A low Te plasma is produced in the processing chamber using energetic beam

    electrons in the 0.5 2.5 keV energy range.

    A separate inductively coupled plasma (ICP) based radical source is used in our system to provide accurate control over relative concentrations of radicals and ions

    Another important element in this plasma processing system is low frequency RF bias capability which allows control of ion energy in the 2 50 eV range

    14

    e-beam source

    Radical source

    Bias (wafer voltage)

    x

  • Y. Zhang et. al., Applied Materials

    Ion / Radical Composition: RF and Low Te Plasmas

    In an RF plasma (with Te = 4.0 eV), significantly more electrons can

    dissociate than ionize due to lower threshold for dissociation.

    In a low Te plasma produced using energetic electrons, radical / ion

    fraction is much lower.

    15

    1 10 100 1000 0

    2

    4

    6

    Cro

    ss-s

    ecti

    on (

    2)

    Energy (eV)

    f e (

    au)

    1.0

    0.8

    0.6

    0.0

    0.2

    0.4

    sion

    sdiss

    fe @ Te = 4.0 eV

    fe @ Te = 0.2 eV

    Ebeam

    1.2 Cl2

  • Y. Zhang et. al., Applied Materials

    Low Te Plasma can etch Si layer-layer with minimal damage

    The top surface can be more quantitatively analyzed using electron energy loss

    spectroscopy (EELS).

    The thickness of the amorphous layer at the top is similar for the unprocessed sample and

    the sample which has been etched in the low Te plasma only.

    When RF bias is applied to increase Ei, the amorphous layer thickness increases.

    The sample that was etched in the inductively coupled plasma without bias shows similar

    damage to the 0.8 W etch case.

    16

  • Y. Zhang et. al., Applied Materials

    These challenges demand new

    film and etch/removal

    capabilities Selective Removal

  • Y. Zhang et. al., Applied Materials Y. Zhang et. al., Applied Materials

    18

    What is Extreme Selectivity?

    SelectraTM Removes Target Material without Damage to Others

    Critical for Patterning and 3D Architectures

    No Damage or

    Residues Remaining

    Multiple Material

    Layers are Formed in

    a Structure

    Extreme Selectivity Enables

    Removal of Only One

    Material

  • Y. Zhang et. al., Applied Materials Y. Zhang et. al., Applied Materials

    Traditional Wet Etch

    Collapse of high aspect ratio

    structures

    Inability to penetrate small

    dimensions

    Traditional Dry Etch

    Lacks extreme selectivity

    Insufficient lateral etch

    control

    New Etch Methods Required to Continue Scaling

    Traditional Etch Technologies Unable to Advance Moores Law

    19

    Tight Features

    0

    20

    40

    60

    80

    100

    10 15 20 25 30

    Coll

    apse

    Per

    centa

    ge

    (%)

    Aspect Ratio

    Pattern Collapse Lateral Control

    Overetch

    at Top

    Insufficie

    nt at

    Bottom

    Graph Courtesy of imec

    Internal

    Image

    Internal Image Internal Image

    Incomplete

    Removal

  • Y. Zhang et. al., Applied Materials Y. Zhang et. al., Applied Materials

    Plasma creates etchant

    chemistry

    Ions are blocked, chemistry

    passes through

    Damage-free, extreme

    selectivity etch without

    polymers

    20

    How Does SelectraTM Achieve Extreme Selectivity?

    The SelectraTM System Creates Tailored Chemistry for Extreme Selectivity

  • Y. Zhang et. al., Applied Materials Y. Zhang et. al., Applied Materials

    21

    Extreme Selectivity Enables 10nm Multi-Patterning

    Post-

    SelectraTM SiN

    Ox

    Ox

    9.3n

    m

    Internal Image

    Pre-

    SelectraTM

    Si

    SiN

    Ox

    Ox

    9.3n

    m

    Internal Image

    No change

    in spacer

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