in-situ production process detection and chamber matching … · • process deviations identified...

InIn--SituSitu Production Production Process Detection and Process Detection and

Chamber Matching Chamber Matching Using Temperature Using Temperature

Metrology Sensors and Metrology Sensors and DiagnosticsDiagnostics

NCCAVSNCCAVSPlasma Etch Users GroupPlasma Etch Users Group

February 12, 2004February 12, 2004

Paul MacDonaldPaul MacDonaldOnWafer TechnologiesOnWafer Technologies

PEUG February 12, 2004PEUG February 12, 2004

Abstract

• Concrete Methodologies and Technology Enabling In-SituDetection of Process Excursions– Wafer-Based Metrology System Overview

• Multiple Production examples that illustrate in-line process excursion detection and chamber matching. – Process monitoring

• Process deviations identified before any device wafers were scrapped• Thermal signatures shown to be early indicators of process instability

and drift – Chamber Matching

• Chambers at sites on different continents are easily matched to ensure process transferability

• Thermal signatures shown to quickly and easily match etch reactors


Monitoring Wafer Temperature in a Plasma System to Diagnose Chamber Problems

• Etching is Impacted by Various Interacting Mechanisms

– Direct Chemical Reaction, Reactive Etching, Deposition, Mask Erosion

• Same Etch Mechanisms are Extremely Sensitive to Temperature

– Temperature is a first order indicator of etching progress or “Health”

• Wafer-Based Metrology of Spatially Resolved Temperature Profiles for all Operating Conditions

• Utilization of Wafer-Based Metrology is Vital for Realizing Real-Time Fault Detection and Isolation

Typical Plasma Etch EnvironmentTypical Plasma Etch Environment

CoolingCoolingFluidFluid

Plasma

HeliumHelium


– Data Analysis System

– Data Transfer Unit

– PlasmaTemp® SensorWafer®

• System Components

PlasmaTemp® In Situ Metrology Hardware OverviewHardware Overview

- Base material is SEMI standard wafer with thermal oxide layer

- Sensor network isolated using a high purity polyimide coating- “System on a Wafer” electronics module for high speed, autonomous

data acquisition & wireless data transfer

- Thermistors located for high resolution thermal profiling


Typical Usage In High Volume Production In High Volume Production FabsFabs and R&D Environmentsand R&D Environments

• PlasmaTemp SenorWafers are Used like any Other Production Monitor– Data Collection Sequence

• Load PlasmaTemp® Wafer in Standard Cassette / Place FOUP in Load Port

• Launch Tool’s Automatic Transfer Sequence

• Run the Standard Production Plasma Etch Recipe– Standard Power, Pressure,

Temperature, etc.• Remove Cassette / FOUP• Download Data

– Immediately Bring Tool Back to Production• No Dummy Wafer• No Particle Test

OnWafer built all the required services for the SensorWafer metrology system

right into a SEMI standard 300mm FOUP. Product is shown with its

convenient “docking station”.


BT Main-Etch

In Situ MetrologySample Mission DataSample Mission Data

MERIE Chamber- 1500W with 30 sec O2 ash- 0oC chuck temperature

Ash

1 Line, 1 Sensor

Typical 3-D View


P lasm aT em p Process Reg im e

0

50

100

150

200

250

0 2000 4000 6000 8000

Total P ow er (W )

Pres

sure

(mT)

200mm 300mm

PlasmaTemp Process RegimeSample Installed Base DataSample Installed Base Data

High Power Si EtchStrip

Silicon Etch& Metal Etch Oxide Etch

PlasmaTemp PlasmaTemp SensorWaferSensorWafer Operates in Operates in All Plasma Process RegimesAll Plasma Process Regimes


0

50

100

150

200

250

Num

ber

of W

afer

s

0 - 0.050.05 - 0.10.1 - 0.150.15 - 0.20.2 - 0.250.25 - 0.30.3 - 0.35

3 Sigma Spread (C)

PlasmaTemp Isothermal 3 Sigma Spread 361 Total Wafers

PlasmaTemp PrecisionFactory CalibrationFactory Calibration

PlasmaTemp Isothermal Absolute Accuracy361 Total Wafers

0

50

100

150

200

250

0 - 0.05 0.05 - 0 .1 0.1 - 0 .15 0.15 - 0 .2 0.2 - 0 .25 0.25 - 0 .3 0.3 - 0 .35

Accuracy (C)

Num

ber o

f Waf

ers • PlasmaTemp Calibration Completed in Stable Thermal Environment– NIST-Traceable Calibration

Standard • Why Calibrate in Isothermal

Environment?– Small Variations in Plasma

Processing are Detected by Sensitive, Accurate SensorWafers

• Absolute Accuracy and 3σ Spread Better than 0.3°C– Data Sample of Last 361 Wafers

Built as of 1/1/04

PlasmaTemp SensorWafersDemonstrate Superior

Calibration Repeatability

Absolute Accuracy to Absolute Accuracy to NISTNIST--Traceable Traceable

Standard Better Than Standard Better Than 0.30.3°°CC

SensorSensor--toto--Sensor Sensor 33σσ SpreadSpread Better Better

Than 0.3Than 0.3°°CC


W a fe r - to -W a fe r R e p e a ta b ilityin P la s m a P r o c e s s e s

8 5

9 0

9 5

1 0 0

1 0 5

1 1 0

1 1 5

Recipe ARecipe BRecipe CRecipe DRecipe ERecipe FRecipe GRecipe HRecipe I

R e c ip e C o n d it io n

Tem

pera

ture

(C)

W a f e r 1

W a f e r 2

W a f e r 3

PlasmaTemp PrecisionWaferWafer--toto--Wafer RepeatabilityWafer Repeatability

• Wafer-to-Wafer Repeatability– Wafer-to-Wafer Repeatability is

Limited by Chamber Repeatability – Typically 2-3%

• Plasma Reactor Variation of Only 1% Equates to as Much as 1.09°C Thermal Variation

– Wafer-to-Wafer Repeatability Better than 1.30°C

• Within 0.21°C of Plasma Reactor Stability Threshold

– Each Data Sample Includes Multiple Runs under Same Conditions

• Different SensorWafers• Same Recipe, Same Chamber

1.291.29°°CC

0.710.71°°CC0.250.25°°CC

0.610.61°°CC

0.060.06°°CC

0.040.04°°CC

0.400.40°°CC 0.830.83°°CC

1.071.07°°CC


Plasma Reactor Optimization and Hardware TroubleshootingTypical ApplicationsTypical Applications

25Torr He BSC

6Torr He BSC

He Cooling Influence

Faulty Source Match

Chucking Voltage Selection

Positive V

Negative V

Process Kit Selection

SiO2 Process Kit

Si Process Kit

Backside Particle DetectionMis-Adjusted Lift Pins

Har

dwar

eTr

oubl

esho

otin

gR

eact

orO

ptim

izat

ion


Data Analysis & CorrelationExample DataExample Data

• Thermal profiles and CD bias are closely related• Data indicates issue with the CD at the Notch (circled)

Spatially-Resolved CD Data can be Easily Analyzed for Correlation to Thermal Profiles

CD Bias and Thermal Profile

40RFH

59RFH

Temperature (°C) CD Bias (nm)38 pts.


• Regular monitoring after known good wafer lots defines baseline tool performance (“fingerprinting”)

• Detect tool problems– Apply Diagnostics Package

• Determine appropriate time for PM and/or WC• Help bring tool back online after PM and/or WC

xx x

xxx x x

x

baseline

x x

Prob

lem

x

x x x x xxx

WC / PMT

time

Routine Temperature MonitoringInIn--Line Fault DetectionLine Fault Detection

x

Chamber Ready

3σ

Tavg


Spatial Modeling Methodology Improving SignalImproving Signal--toto--Noise RatioNoise Ratio

• Profile A and Profile B Show the Same Mean and Range but VERYDifferent Thermal Profiles

• OnWafer has Developed a Modeling Approach to Determine Spatial Chamber Health Signal and Minimize Normal Noise Due to Chamber Variations

• Metric Must be Able to Capture Change in the “Shape” of the Thermal Profile while Filtering Standard Chamber Fluctuations

• Shape-Fitting Metric is Denoted in the Next Slide by “O-Factor”

22--D Temperature Profile BD Temperature Profile B

Mean T: 85°C

Ran

ge 1

0°C

22--D Temperature Profile AD Temperature Profile A

Ran

ge 1

0°C Mean T: 85°C


T h e r m a l a n d F a b D a ta C o r r e la tio n

0 .0 0

0 .2 0

0 .4 0

0 .6 0

0 .8 0

1 .0 0

1 7 13 19 25 31 37 43 49 55 61 67 73 79 85 91 97 103

109

115

121

127

133

139

145

151

157

D a y

O-F

acto

r

IS S U E O -F ac to r

• Thermal Data and Fab Data Collected over 140 days • Temperature is Used as a Proxy for Chamber Health • In-Situ Thermal Measurements Identified 2 out of 3 Fab

Issues Prior to Any Other In-Line Measurements– Increasing Data Collection Frequency Improves O-Factor Resolution

Process Deviation IdentificationExample 1Example 1

Issue

Issue

Missed

NormalNormal

Normal

Normal

Normal

Normal

Normal Normal


Process DriftWet Clean CycleWet Clean Cycle

• Temperature Mean and CD Bias Mean Show Steady Increase over Wet Clean Cycle

• Wet Clean Trigger Point Determined to 90RFh– CD Within Spec @ <.85nm (normalized)– Thermal Range within Spec @ <0.05°C (normalized)

Defining Wet Clean TriggerMERIE Reactor

0.8

0.9

1

33RFh 55RFh 67RFh 48RFh 100RFh

Norm

aliz

ed T

empe

ratu

re (

o C)

0

0.6

1.2

Norm

aliz

ed C

D (n

m)

Mean Temperature CD BIAS


Chamber Matching

0.82

0.84

0.86

0.88

0.9

0.92

0.94

0.96

0.98

1

1.02

1A 1C 2B 2A 1B 1D

Chamber

Nor

mal

ized

Mea

n Te

mpe

ratu

re (o C

)

0

0.2

0.4

0.6

0.8

1

1.2

Nor

mal

ized

Tem

pera

ture

Ran

ge

(o C)

Mean Temperature Temperature Range

Chamber Matching6 Chamber Population 6 Chamber Population –– Single SiteSingle Site

• 6 Chambers Examined– One Chamber Clearly

Out of Distribution• Custom Process Kit

– Two Pairs of Chambers Well Matched

– Last Chamber at Distribution Median

• Hardware Changes Implemented to better Match Chambers– Chiller Adjustment

Resolved Tool 1 and Tool 2 Thermal Disparity

ChambersMatched

Cha

mbe

r Dev

iatio

n

ChambersMatched


Chamber Matching Results

70 75 80 85 90 95 100 105

1A

2C

4A

3B

3C

3D

3A

Cham

ber

Temperature (C)

Step 1 Step 2 Step 3 Step 4

• 7 Chambers, Multiple Steps Examined

• Tool 3 Shows Excellent Mean Matching– Within 1.29°C for all Steps

• Chambers 4A and 2C Did Not Respond Normally to Process Steps

• Chamber 1A was Running 2°C Warmer than Tool 3

• All Deviations Required Hardware Repair

Chamber Matching7 Chamber Population 7 Chamber Population –– US and Europe SitesUS and Europe Sites

WellWell--MatchedMatchedChambersChambers


HeatFlux™Advanced Analysis ToolAdvanced Analysis Tool

Plasma Application Module• Analyzes the data from a

single PlasmaTemp run• Determines:

– Cooling efficiency across the area of the chuck

– Heating uniformity of the plasma• This enables:

– Differential diagnosis of chuck or plasma-related heating problems in production

– Analysis of chamber/chuck geometries during equipment design

– Identify the Root Cause of Reactor Issues

HeatFlux

Temporal ProfileMain Etch Step from a 200mm

Poly Etch System

Chuck’s Conductance Profile


Chamber MatchingActing on Thermal DataActing on Thermal Data

• Week 1

• Week 2 - Deviant



• Week 5 - Resolved

Conductance AnalysisConductance Analysis• Thermal Profile Shift in Thermal Profile In Chamber • Action is Required to Resolve Discrepancy• Correlated to Edge-Specific Yield Issue•HeatFlux™ is Applied to Separate Plasma and Chuck Effects on the Wafer

• Conductance Analysis Clearly Show Chuck Thermal Transfer Efficiency Change in Weeks 2 – 4• Process Kit Change Resolves Issue


Summary

• Concrete methodologies for in-situ detection of process excursions and rapid chamber matching demonstrated

• Multiple examples that illustrate in-line process excursion detection and chamber matching. – Process monitoring

• Process deviations are identified in-line • Temporal/spatial temperature signatures show early indicators of

process instability and drift – Chamber Matching

• Chambers at one site, and chambers at sites on different continents are matched

• Temporal/spatial temperature signatures quickly and easily matchetch reactors

• Advanced modeling allows component-level troubleshooting

in-situ production process detection and chamber matching … · • process deviations identified...

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