Analysis and Prediction of Polish Profiling...Wafer Position (mm) Polish profile Experimental 0 kPa 50 kPa 0.5 1.0 1.5 90 100 Wafer Position (mm) RR force co-eff k2 FEM analysis 0

Ebara Corporation - Slide 1

Manabu Tsujimura, David Watts1

Ebara Corporation, 1Ebara Technologies Inc.

Analysis and Prediction of Polish ProfilingAnalysis and Prediction of Polish Profiling


Year of First Shipment 1999 2002 2005 2008 2011Technology Generation(nm) 180 130 100 70 50Planarity(nm) 18 14 11 9 7Aspec t r a t i o (Cu) 1. 4 1. 5 1 . 7 1. 9 2 . 1Metal effective resistivity(µ O -cm) 2. 2 2. 2 2 . 2 1. 8 <1. 8I LD effecteve dielectr ic constant(k) 3. 5- 4. 0 2. 7- 3. 5 1 . 6 - 2 . 2 0. 5 <0. 5Barr ier th ickness (nm) 17 13 10 0 0Wafer size (mm) 200 300 300 300 450

The “super planarity” requirement by ITRS demands that ALLALL CMP tools must have

““ProPro--ActiveActive”” Profile ControlProfile Control

What is the Message From ITRS ?What is the Message From ITRS ?

Brick WallBrick Wall


What is What is ““ProPro--Active Profile ControlActive Profile Control””??

Wafer

Uniformdeposition

Wafer

Non-uniformdeposition

Wafer

Uniformpolish

Wafer

Non-uniformpolish

ProPro--Active profile control is the ability to produce Active profile control is the ability to produce uniform polish profiles regardless of the incoming uniform polish profiles regardless of the incoming wafer deposition profile.wafer deposition profile.

Proactive (pro ak’tiv), adj. Serving to prepare for, intervene in,or control an expected occurrence or situation


Examples of Six Different Cu Deposition ProfilesExamples of Six Different Cu Deposition Profiles

+Anode

Chemical

Contact

Wafer

-

0.2-µ m dia. AR=4.50

200

400600

800

1000

12001400

0 5 10 15 20Distance from edge (mm)

Cu

thic

knes

s (n

m)

33%66%100%33%66%100%

PV= 200nm

5mm ==>? =5x4=20mm

Edge ProEdge Pro--profile control is required.profile control is required.


Wafer carriercenter profile

Several Methods to Improve CMP PerformanceSeveral Methods to Improve CMP Performance

Back side pressureRetainerpressure

Uniform pressure distributionUniform relative speed

Uniform conditioning

Uniform slurry supply

Uniform movement

Uniform temperature

Wafer carrier edge profile


ProPro--Active Profile Control for CLC & APCActive Profile Control for CLC & APC

Planarity requirement- Step height of ILD- Dishing & Erosion- Pro-active control

of polish profile

Best profileInitial polishprofile

Change of consumables

BSP press.

RR press.

Head center profile

Head edge profile

Center profile

Edge profile

Parameters to control profile

Slurry supplyDressing

Linear speedOthers

Consumables-Pad-Slurry-Backing film


A Polish profile is predicted by the following equation, based on Preston’s equation;

q (r)= k0 (r) k1 (r)k2 (r) k3 (r) k4 (r) p (r) v (r)where,

q (r): Polish quantityk0 (r): Basic proportional co-efficientk1 (r): Back-side pressure co-efficientk2 (r): Retainer-ring pressure co-efficientk3 (r) : Head center-profile co-efficientk4 (r): Head edge profile co-efficient

p (r):Pressure on polished waferv (r):Linear velocity

Basic Calculation EquationsBasic Calculation Equations


The analysis is performed under the following consumable set and experimental conditions:

Slurry :SS25Pad :IC1000/Suba 400Backing film :NF200Speed Carrier/Table :30/30 rpmCarrier force :500 g/cm2

Retainer-ring force :0-700 g/cm2

ILD :TEOS

V (r)=V (0)=0.5 m/secv(r)=V (r)/V (0)=1q (r)=k 0(r) Basicqq ’’((r)=r)=kk 00((r)r)??kk 11 ((r)r)??kk 22 ((r)r)??kk 33 ((r)r) ImprovedImproved

Conditions for AnalysisConditions for Analysis


FEM Mesh drawing

X· Y direction restriction


Wafer load

Retainer ring load

Effect of Retainer Ring ForceEffect of Retainer Ring Force


Wafer Position (mm)

Pol

ish

pro

file

Experimental

0 kPa

50 kPa

0.5

1.0

1.5

90 100

Wafer Position (mm)R

R f

orce

co-

eff k

2

FEM analysis

0 kPa

50 kPa

0.5

1.0

1.5

90 100

0.360.4

4%

FEM analysis follows the same trend as experimentFEM analysis follows the same trend as experiment

Effect of Retainer Ring ForceEffect of Retainer Ring Force




Uniform load

FEM Mesh drawing

Convex Concave

Effect of Head Center ProfilesEffect of Head Center Profiles


0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

-100 -75 -50 -25 0 25 50 75 100

Pol

ish

pro

file

Wafer Position (mm)

Wafer Position (mm)

Head center effect

co-eff

k3

0.8

1.0

1.2

0 50 100

? F E M ?

? F E M ?

0.04

Effect of Head Center ProfilesEffect of Head Center Profiles

Convex

Concave


Polish profile

1.0

1.2

0.8

Wafer position ( m m )-100 0 100

BSP= 0 kPaBSP= 20 kPaBSP= 30 kPa

0.8

1.0

1.2

0 50 100Wafer position ( m m )

BSP= 0 kPaBSP= 20 kPaBSP= 30 kPa

BSP Co-eff k

1

Effect of Back Side PressureEffect of Back Side Pressure

Wafer

Back side pressureWafer carrier

Pad

Table

Back side holes

P

N 2


Analysis

0.190.22

80 90

0.190.25

Wafer position ( m m )

0 50100

Base profile

Improved profile

Experimental

0.5

1.0

1.5

Polish rate profile

0.5

1.0

1.5

Polish rate profile

Base profile

Improved profile

0 50 100

3 %

0 %

0.5

1.0

1.5

Polish rate profile

Analysis

Base profile

Improved profile

Wafer position ( m m )

90 95100

Experimental

Base profile

Improved profile

0.5

1.0

1.5

Polish rate profile

0.34

0.28

1mm

90 95 100

6 %

Comparison of Analysis and Experimental DataComparison of Analysis and Experimental Data


1 Back-side effect co-efficient k1 has been obtained by experiment.

2 Retainer-ring force effect co-efficient k2 has been obtained by FEM analysis and has been confirmedto be highly predictable.

3 Carrier center-profile effect co-efficient k3 has been obtained by FEM analysis and confirmed to be highly predictable.

4 Carrier-edge profile effect co-efficient k4 has been obtained by experiment.

5 The analysis and presented example shows that the modelis acceptable for predicting polish profiles.

6 This type of analysis will be useful for automated CMPclosed-loop control.

CONCLUSIONCONCLUSION

Documents

Analysis and Prediction of Polish Profiling...Wafer Position (mm) Polish profile Experimental 0 kPa 50 kPa 0.5 1.0 1.5 90 100 Wafer Position (mm) RR force co-eff k2 FEM analysis 0