EV GroupTemporary Bonding – HVM Concerns

Markus WimplingerCorporate Technology Development and IP DirectorM.Wimplinger@Evgroup.com

To be presented at the “Enabling 3D: Temporary Bonding Workshop” by Sematech, July 11th 2011

EV Group

EVG TB/DB History of Innovation

2000

EVG850TBthermal release Tapes

up to 8“

EVG850DBthermal release Tapes

up to 8“ EVG850TB/DBFilmFrame Mounting

up to 6“

EVG850TBWax-Bonder

up to 6“

EVG850TBLw/ Tape Lamination

up to 4“ EVG850DBSlide-Off DeBonder

up to 4“

EVG850TB/DBBrewer HT 8“

EVG850TB/DBBrewer HT 12“

2002 20082004 2006 2010

ZoneBONDTM2010

EV Group

Customer’s Requirements

Low Cost TB / DB does not add value to the product. The potential for differentiation of TB / DB technology

lies in its capability to enable cost reduction for 3D IC related process steps

Very High Yield Mature Technology Integrates well with Customer Process Flow Infrastructure / Supply Chain established

EV Group

Temporary Bonding / Debonding Process Flow

EVG850TB EVG850DB

(Immediate) Re-use of Carrier Wafer

Proc

ess

Inte

grat

ion

EV Group

Choices to be made…

In what order shall the choices be made? …From fundamental issues to more specific

issues… Carrier Selection Adhesive Selection TB / DB Method Handling Strategy for Debonding Edge Protection Strategy Metrology Strategy

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Easy, any Si-wafer can be used

Challenging, usage of new material required

Logistics, further internal use

OK. Standard and qualifiedtoday

Backside alignment via IR light

multiple times typically > 100x

75-200 Wx(mxK)-1

Perfect match to Si

Silicon

ChallengingElectrostatic Chucking

Backside alignment via visible light

Double Side Lithography

multiple times typically > 100x

Re-usability

1,2 Wx(mxK)-1Thermal Conductivity

Good match to SiThermal Expansion

Glass (Borofloat, Pyrex)

Comparison of Si and Glass Carriers for Thinned Si Wafers

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Carrier Selection

Si or Reclaim Si IntegrationSi or Reclaim Si Infrastructure

Si or Reclaim Si Maturity AnyHigh YieldReclaim Si Low Cost Options:

• Glass Carrier• PerforatedGlass

• Si Carrier • Reclaim Si

Si carriers or reclaim Si carriers seem to become thepreferred option by customers due to the benefitsprovided. Not all TB / DB technologies are compatible with Si carriers however.

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Adhesive Selection

ThermoplasticIntegrationThermoplasticInfrastructure

? Maturity ? High Yield? Low Cost Options:

• Thermoplastic• Cross-linking

• EVG‘s focus is on thermoplastic adhesives mainlydue to advantages with regards to process integration.

• A broad supply chain for thermoplastic adhesiveshas always been available and is available foradvanced, high temperature thermo-plastic adhesives.

(i.e. Brewer Science Inc.)

good chance!

good chance!

good chance!

EV Group

Thermoplastic Adhesive TB DB Technologies

Solvent Release DBTechnology with perforatedcarriers

Slide DB Technology with blankedwafers

ZoneBondTM DB Technology with blanked (treated) carriers

Limitations:- Expensive carriers - Perforated carriers- Typically glass carriers- Slow DB process- Risk of adh. squeeze through during bonding- High solvent consumption

Limitations: - DB process at elevated

temperature - Thermal stability of adhesive

linked to DB temperature- Scalability to larger wafer size (450mm)

Limitations:- None

Potential: Development of specialized adhesives

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Untie Max Process Temp. from Debond Temp.30

0

Technology

200

100

T[°C]

Slide-off Debond RT DebondZoneBondTM

DB Temp

Max Process Temp

ZoneBONDTM

EV Group

Process Requirements – Example ZoneBondTM

Carrier Selection & Preparation:

• Si and glass as carrier materials are feasible

• Flexibility on dimensions

• Simple surface treatment to reduce adhesion to adhesive in center zone.

EV Group

Process Requirements – Example ZoneBondTM

Compatibility with Product Wafers:

• Compatibility to product wafers with varying topographyTypical wafer topography:

• <10µm / ~40µm / ~80µm

• The same adhesive will work for different product wafer surfaces. No adhesive modification required.

EV Group

Process Requirements – Example ZoneBondTM

Edge Protection Strategy:

• For same size carrier wafers, edge trimming is highly recommended to ensure optimized edge quality

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Process Requirements – Example ZoneBondTM

Adhesive Coating:

• Either carrier wafer or product wafer may be coated with adhesive

• Adhesive selection based on process requirements

• Adhesive thickness may be adjusted according to product wafertopography.

Aspects of the

concept are both

patent pending

and patented

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Process Requirements – Example ZoneBondTM

Bonding:

• Thermal bonding process

4µm3µm1µm

Q4 2011

3µm6 ~ 8µm100µm2µm4µm50µm1µm2µm20µm

Q2 2012TTV todayBondline

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Process Requirements – Example ZoneBondTM

Wafer Thinning:

• Usually performed by rough grinding and fine grinding & stress relief (wet / dry etching and / or polishing).

• Rigid support during backgrinding and polishing is critical. Only fulfilled by thermoplastic adhesives and non-perforated

carriers today.

EV Group

Process Requirements – Example ZoneBondTM

Backside processing – typical process steps:- Reflow- Cleaning- CMP

- W2W Bonding- (PE) CVD- Sputtering- Electroplating

- Etching- Lithography- Dielectric curing- C2W attach

Thermo-mechanical stability of adhesives is the biggest challenge today.

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Process Requirements – Example ZoneBondTM

Dicing Frame mounting of entire bonded stack prior to Debond:

• Most reliable way of handling thin wafer during Debondingoperation.

Patented

Process Flow

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Process Requirements – Example ZoneBondTM

Edge Zone Release - EZR® Process:

• Dissolve adhesive at the wafer edge using solvent

• Dissolution speed enhanced by Megasonics

• 10 to 15 uph* per process module are achievable. * For optimized processes.

Hardware & process

solution patent

pending

EV Group

Process Requirements – Example ZoneBondTM

Edge Zone DeBond - EZD® Process:

• Load assembly onto EZD® station

• Lift off carrier wafer

• Cycle time < 90 sec. feasible

• Separation always between adhesive and carrier. Separation process independent of device wafer surface!

Hardware & process

solution patent

pending

EV Group

Process Requirements – Example ZoneBondTM

Cleaning & Spin Drying:

• Thermo-plastic adhesive may be cleaned with solvent

This enables:

• Optimized cleanliness

• Gentle to device wafer topography

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Process Requirements – Example ZoneBondTM

Thin product wafer ready for backend assembly process

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In-line Metrology for TB

Wafer thinning is an operation that results in a non-reworkablecondition. Therefore, it is critical to ensure that criticalparameters of the thin wafer support system are withinspecification prior to thinning. Of interest are: Excursion in adhesive thickness uniformity & absolute value Excursion of carrier thickness uniformity & absolute value Bonding voids

Strategy: Employ in-line metrology to detect such issuesbefore further processing of the wafers downstream to: Enable rework before wafers are in a non-reworkable state Reduce the material that is mis-processed.

EV Group

In-line Metrology for TB

- 100% inspection of bonded wafers prior to thinning is desired.

- EVG has developed an in-line metrology solution that offers a throughput that is compatible with 100% in-line inspection of bonded wafers in an automated Temporary Bonding system

- Details will be presented in the “SEMATECH 3D Interconnect Metrology Workshop” on Wednesday this week.

- Adhesive thickness and TTV

- Carrier thickness and TTV

- Voids

EV Group

Summary: How are we doing?

Customer Requirements: Low Cost Very High Yield Mature Technology Integrates well with Customer Process Flow Infrastructure / Supply Chain established

Standards and quasi-standards are evolving. …We are getting there…

EV Group

EV Group

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