October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Keiichi Kimura, Katsuya Nagayama, Yosuke Inatsu, Panart

October 13, 2006

Kyushu Institute of TechnologyKyushu Institute of Technology 　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　　 Prof. Keiichi

Kimura　

Keiichi Kimura, Katsuya Nagayama, Yosuke Inatsu, Panart KhajornrungruanDepartment of Mechanical Information Science and Technlogy,

Kyushu Institute of [email protected]

2006 ICPT

A lodestar on pad groove pattern A lodestar on pad groove pattern design design

with slurry flow analysis with slurry flow analysis and visualization experiments and visualization experiments

in CMP processin CMP process

A lodestar on pad groove pattern A lodestar on pad groove pattern design design

with slurry flow analysis with slurry flow analysis and visualization experiments and visualization experiments

in CMP processin CMP process

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Outline

1. Introduction

2. Computational analysis method

3. Visualization experiment method

4. Basic slurry flow

5. Slurry flow simulation and visualization experiments

6. Lodestar of groove pattern design

7. Conclusion

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Configuration of CMP machine & processConfiguration of CMP machine & process

Material removal

Interaction among 3 factors

wafer surfacewafer surface

slurryslurry

polishing padpolishing pad

Slurry

Polishing Pad

Silicon Wafer

=

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Material removal between wafer and pad surfaceMaterial removal between wafer and pad surface

wafer surface

slurry

polishing pad

Silicon wafer

Polishing pad V

supply & drainagesupply & drainageslurry flow slurry flow

wafer and pad contactphysical & chemical contact

material, surface asperity

chemical & particles

material & asperity

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polishing conditions polishing speed polishing pressure

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122.5

455

200

1

2

polishing pad

wafer

(a) Concentric groove pattern

(b) Radial groove pattern

Configuration of CMP model & polishing padConfiguration of CMP model & polishing pad

pitch of grooves : 2 mmwidth of groove : 1 mmwidth of land : 1 mmdepth of groove : 1 mm

angle bet. grooves: 11.25 deg. (32 divisions)width of groove : 1 mmdepth of groove: 1 mm

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Pad Edge

Wafer

Pad center

Grooves

- Concentric groove Lattices : 1,000,000

- Radial groove Lattices : 600,000

Computational model between wafer and groove padComputational model between wafer and groove pad

0

vt

gvvpvvvt

T

fsfff CDCvCt

2,)()(

Heat fluid analysis code : FLUENT 6.2

- Continuity equation

- Navier-Stokes equation

- Diffusion equation for slurry transportation

GrooveGap Height

wafer

1 mm

1 m

m

Groove cross-section(not in scale)

10 mgap

padgroove

wafer

1 mm

1 m

m

Groove cross-section(not in scale)

10 mgap

padgroove

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DI water + fluorescent agent

polishing padquartz glass

UV light source

video camera

fluorescent light

- Quartz glass : 200 (Supersil-P30 / ShinEtsu Quartz)

- Fluid (Slurry) : DI water

- Fluorescent agent : FWP-1 / Karl Deutsch

- Ultraviolet light source : High pressure Mercury lamp (SHG-200/Mejiro Precision)

- Polishing machine : NANOTECH 450-FODCAb/Nanotech Machines)

Experimental set-up for slurry flow visualizationExperimental set-up for slurry flow visualization

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Equal direction area : smooth flow

Opposite direction area : jammed flow

Basic slurry flow between wafer and padBasic slurry flow between wafer and pad

1. Slurry flows in thin space between wafer and polishing pad

2. Slurry flow is affected by the motion of wafer and polishing pad

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Slurry movement on polishing padSlurry movement on polishing pad

slurry supply

polishing

slurry drainage

: (a) Groove pattern on pad surface (b) Groove cross section geometry

: (c) Pad surface asperity

: (a) Groove pattern on pad surface (b) Groove cross section geometry

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Grooves on polishing pad 1. Slurry transportation canal 2. Slurry reservoir

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Slurry flow simulation : No-groove padSlurry flow simulation : No-groove pad

1 slurry flows in from right side

2 slurry spreads in area of [A]

3 slurry flows down in left area

4 slurry delays flowing in area [B]- No-groove pad- 1 : 60 min-1, 2 : 60 min-1

- slurry flow at 5m below wafer

2

1

[A]

[B]

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Slurry flow simulation : Concentric groove padSlurry flow simulation : Concentric groove pad

Polishing pad rotation

Wafer rotation

: 1=60 min-1

: 2=60 min-1

1. Slurry flow in from right side of wafer

2. Slurry spreads around from upper side of wafer followed by rotation of wafer

3. Slurry flow delays at bottom side of wafer due to opposite rotation of wafer and pad

4. Shape of delayed slurry flow area is slightly different from no-groove pad

5. Concentric groove pattern can take in and reserve slurry beneath wafer

Slurry flow at 5 mm below wafer

simulation

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Wafer rotation

: 1=90 min-1

: 2=30 min-1


1. Slurry flows is slightly different from the case of 1=2.

2. Slurry flowing time over whole wafer is short.

3. Delayed slurry flow area is small.

4. Pad rotation influences slurry flow strongly.

simulation

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1 > 2

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Wafer rotation

: 1=30 min-1

: 2=90 min-1


simulation

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1 < 2

1. Slurry flows same as the

case of 1=2.

2. Slurry flowing time over whole wafer is not short.

3. Delayed slurry flow area is large.

4. Influences of wafer rotation for slurry flow is not much.

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Wafer rotation

: 1=60 min-1

: 2=60 min-1

1. Slurry flow in from right side of wafer

2. Slurry spreads around from upper side of wafer followed by rotation of wafer

3. Slurry flow delays at bottom side of wafer due to opposite rotation of wafer and pad

4. Shape of delayed slurry flow area is slightly different from no-groove pad



simulation

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Slurry flow experiment : Concentric groove padSlurry flow experiment : Concentric groove pad


Wafer rotation

: 1=30 min-1

: 2=30 min-1

visualization experiment


2. Delayed slurry flow area is existed at the bottom side of wafer

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Slurry flow analysis : Radial groove padSlurry flow analysis : Radial groove pad

simulation


Wafer rotation

: 1=60 min-1

: 2=60 min-1


1. Radial groove pattern can take in slurry, and spread as sweeping fan shape

2. Slurry drainage is carried out quickly

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3. Radial groove gives great influences for slurry flow.

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Slurry flow experiment : Radial groove pad2Slurry flow experiment : Radial groove pad2

visualization experiment


Wafer rotation

: 1=30 min-1

: 2=30 min-1

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1. Radial groove pattern can take in slurry, and spread as sweeping fan shape

2. Slurry drainage is carried out quickly

3. Radial groove gives great influences for slurry flow.

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+ =

Concentric groove Radial groove Combined grooveCombined groove

Concentric groove pad : good to take in and reserve slurry

+

Radial groove pad : good to drain slurry quickly

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Geometry of combined grooveGeometry of combined groove

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Slurry flow simulation : Combined groove padSlurry flow simulation : Combined groove pad


Wafer rotation

: 1=60 min-1

: 2=60 min-1

1. Slurry flow on combined groove pad is similar to that of concentric groove pad


simulation

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2. Delayed slurry flow area is disappeared

3. Slurry replacement over whole wafer is completed quickly

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Lodestar of groove pattern designLodestar of groove pattern design

1.1. Basic functions of grooves on polishing pad are …Basic functions of grooves on polishing pad are …(a) to transport slurry beneath wafer(a) to transport slurry beneath wafer(b) to reserve slurry (b) to reserve slurry (c) to drain slurry to outside of polishing pad(c) to drain slurry to outside of polishing pad

2. Concentric grooves have functions of (a) and (b).2. Concentric grooves have functions of (a) and (b). - grooves are closed shape in rotating direction and no open - grooves are closed shape in rotating direction and no open orifice orifice

3. Radial grooves have function (c).3. Radial grooves have function (c). - all grooves have open orifice- all grooves have open orifice

4. Combined grooves have functions (a), (b) and (c).4. Combined grooves have functions (a), (b) and (c). - it is important to combine concentric grooves and radial - it is important to combine concentric grooves and radial groovesgrooves

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1.1. Computational analysis and visualization experiments Computational analysis and visualization experiments were attempted on slurry flow in CMP polishing pad.were attempted on slurry flow in CMP polishing pad.

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ConclusionConclusion

3. Basic function of groove pattern such as concentric 3. Basic function of groove pattern such as concentric groove groove and radial groove is analyzed with analysis and and radial groove is analyzed with analysis and experiments. experiments.

4. Advantages on combined grove is analyzed.4. Advantages on combined grove is analyzed.

5. Lodestar for groove pattern design is established.5. Lodestar for groove pattern design is established.

2. Computational analysis and visualization experiments 2. Computational analysis and visualization experiments provided similar phenomena each other.provided similar phenomena each other.

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AcknowledgmentAcknowledgment

We are indebted to We are indebted to Dr. K. HiedaDr. K. Hieda, , Dr. K. KuriyamaDr. K. Kuriyama

and and JSR corporationJSR corporation for their great support and for their great support and

discussion with us on the research. discussion with us on the research.

We express plenty of appreciation to them.We express plenty of appreciation to them.

Documents

October 13, 2006 Kyushu Institute of Technology Kyushu Institute of Technology Prof. Keiichi Kimura Keiichi Kimura, Katsuya Nagayama, Yosuke Inatsu, Panart