J. Stegeman

Veldhoven, 2017-01-29

Outgassing Measurements @ ASML

Introduction

• For the ASML NXE program, EUV lithography, outgassing rate is

an important parameter for the overall quality and costs.

• For this purpose, approximately 100 RGA qualification tools are in

place at 40 suppliers World Wide

• Total investment: ~ € 10,000,000

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Confidential

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RGA Qualification Tools

Performance influenced by:

• Geometry and Dimensions

• Choice of components

• Quality/Health of Sensors

• Location/orientation sample

• Knowledge/Discipline of supplier

• Taking shortcuts

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Confidential

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RGA Tooling: Large diversity Standardization23 May 2017

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Qualification of RGA tools: Round Robin Method

• Round Robin Method

• Repeatability (within tool)

• Reproducibility (Compared to reference values)

• Current RR approach high impact on RGA tool availability

• POM and PE sheet material, no traceable reference value available

• 3 Measurements

• Impact 2-3 weeks per year per RGA tool

• Goal: Development International Outgassing Standard

• Primary Standard (PTB)

• Outgassing Source (Vapor) Dodecane

• Timing: 2017

• Successor for the current RR method

• Impact on RGA tool availability from 2 weeks 2 days

23 May 2017

Confidential

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Installed Base: World Wide23 May 2017

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Practical Outgassing Standard: Set-up

• Every ASML related RGA tool is equipped with a

gas inlet port for calibration purposes, This port

is used to administer Dodecane.

• To generate a stable flow of Dodecane, the

following device was constructed:

• A small volume (~20 cc) filled with Dodecane

• The two valves to prevent contact between

Dodecane and the orifice during transport.

• This device, or Outgassing Source, will be

connected to the (automated) valve available on

the RGA tool.

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Slide 7

3: Manual Valve

1: Manual Valve

2: Orifice

Dodecane

Liquid

Dodecane

Vapor

Outgassing standard: Characteristics

• For ASML related parts, the most commonly used RGA

qualification tool is the D&M NGQ system (40+ systems).

• With this NGQ system, first the characteristics of the Outgassing

Standard were determined

• Dynamic System Response

• Stabilization time: Dodecane concentration when valve is opened

• Recovery time: RGA tool when the supply is closed

• Mass discrimination

• How well traverse the fragments through the mass filter (ref: NIST)

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Confidential

Slide 8

Outgassing standard: Gage Repeatability Study

• When characterizing the system dynamics, the repeatability of the RGA tool was also studied.

• To reduce/prevent human factors, the admission of Dodecane to the RGA qualification tool is automated via an automated valve between the device and the RGA tool.

• Repeatability of the RGA tool depends on temperature effects:

• Electronic sensor drift

• Surface desorption rate

• Conductance variation

• Dodecane vapor pressure

• Contamination build-up (recovery)

• To reduce the effect of temperature fluctuations, the Repeatability study was carried out in a temperature controlled Clean Room

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Slide 9

Outgassing standard: Characteristics & Gage Repeatability Study

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Slide 10

Pump System

RGA

NGQ

RGA Qualification Tool

Automated

valve

QDodecane = PDodecane * Seff

Outgassing Standard: Test Sequence23 May 2017

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Slide 11

Dodecane Round Robin: Gage Repeatability Study

Pre

par

atio

nR

epea

tab

ility

Seq

uen

ceA

fter

-Car

e

Phase

Start Gage Repeatability

RGA Validation Generate BG scanBake RGA System Vent RGA SystemConnect RR

DevicePump Down RGA

SystemOpen Manual valves 1 & 2

Start RR Sequence

> 50 CyclesRR: Measure 60

minutesClose Automated

ValveBG: Measure 30

minutes

Close Manual Valves 1 & 2

Vent RGA SystemDisconnect RR

DeviceBake RGA System Generate BG scan

End Gage Repeatability

Open Automated Valve

Characteristics outgassing standard: Dynamics (1)

Observations:

1: Water level is still decreasing after 100 cycles during 70+ hours

2: Hydrocarbon levels are stable after 10 hours

3: At first sight, first five to ten cycles with RR are not stable

4: Sometimes the signal is significantly higher, cause unknown, possible timing issues

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Characteristics outgassing standard: Dynamics (2)

Observations:

Every Cycle with Dodecane starts with a higher signal for both CxHy-v and CxHy-nv

• Cause: Flow stabilization and vapor pressure build up in the supply line while the automated valve is closed

• Data points 3, 4 and 5 used for repeatability calculations

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Slide 13

1

23 4 5 6

Characteristics outgassing standard: Dynamics (3)

Observations:

For all major Dodecane peaks over

the full mass scale, background levels

drops below 1%

BG subtraction is therefore not

needed

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Characteristics outgassing standard:

Mass Discrimination: Background

• Background information:

• Every RGA with a quadrupole mass filter will face mass discrimination.

• Mass discrimination leads to lower sensitivity for higher masses passing through the mass filter.

• Main driver for this effect is the lower conductance for the heavier ions, generated from the different species in the

vacuum being analyzed.

• To investigate this effect for the Dodecane in this test, the measured values were compared with the Dodecane

reference scan from NIST.

• Approach:

• Every major peak of the fragmentation pattern was normalized against the main peak, m/z = 57.

• Peaks with an m/z lower than 57 were omitted, only higher masses were of interest.

• These normalized values were compared with the NIST values.

• Investigate the relation between the mass of the ion and the deviation with the NIST spectrum

• All 50 cycles, with data points 3, 4 and 5 were taken into account.

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Characteristics outgassing standard:

Mass Discrimination: ResultsFrom the graph it is clear that there is a linear correlation between m/z and the deviation between the ASML outgassing standard and NIST.

This correlation is then used to correct the measured intensities

The results are shown in the last column of the table

The effect of mass discrimination can be minimized using this correlation

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Slide 16

m/z NIST ASML Factor ASML-corr

57 100% 100% 1.00 100%

71 54% 50% 0.94 56%

85 33% 25% 0.76 31%

99 5.9% 4.3% 0.73 6.0%

113 4.0% 2.4% 0.60 3.8%

170 5.3% 1.4% 0.27 5.6%

Round Robin Repeatability Study: First results (1)

Observations:

First two Data Points are not usable due to too large fluctuations

• The average for every Data Point is calculated

• Every Data Point is compared to this average value

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Round Robin Repeatability Study: First results (2)

Repeatability calculations:

For the last 45 RR-cycles (cycle 6 to 50)

• The average of sample points 3, 4 and 5 is taken

• This is done for each of the top-10 masses for Dodecane

• For the 45 cycles, the average is calculated for every mass

• The variation of all masses is plotted against the average value

• There is a strong relation with the temperature

• 1 degree C ~ 10% outgassing deviation

• Probable cause: Temperature stimulated Vapor pressure in Outgassing Device

• Dodecane ΔHvap = 61,800 J/Mol

• T1=301K (28C), T2=302K (29C)

• Pvap = 18.00 19.53 Pa

• Increase of 8.5%

• Courtesy of NIST data

• Extra effect: temperature stimulated desorption of Dodecane from walls

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Round Robin Repeatability Study: First results (3)

Strong correlation between Temperature and the outgassing of Hydrocarbons.

Correlation improves over time, the correlation during the last 25 Hrs is very strong.

Water has also a correlation between Temperature and Outgassing, but the correlation changes during the Repeatability Study

Question, can the outgassing be corrected for the temperature?

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Slide 19

110%

95%

80%

110%

95%

80%

29.529.028.528.027.5

300%

200%

100%

CxH

y-v

CxH

y-n

v

Temp

H2O

Complete Data Set

110%

95%

80%

110%

95%

80%

29.529.028.528.027.5

300%

200%

100%

CxH

y-v

CxH

y-n

v

Temp

H2O

First 25 Hrs

110%

95%

80%

110%

95%

80%

29.529.028.528.027.5

100%

75%

50%

CxH

y-v

CxH

y-n

v

Temp

H2O

Between 25 and 50 Hrs

110%

95%

80%

110%

95%

80%

29.529.028.528.027.5

100%

75%

50%

CxH

y-v

CxH

y-n

v

Temp

H2O

Last 25 Hrs

Round Robin Repeatability Study:

Preliminary Conclusion

• The first tests shows:

• Due to pressure build up, 20-30 minutes is needed to stabilize the vapor flow

• RGA Tool needs stabilization time, reaching desorption/resorption equilibrium, saturation time

• Repeatability better than +/- 10%

• 8.5 % explained by the Temperature vs. Vapor pressure relation (Clausius-Clapeyron equation)

• Temperature corrected outgassing rates possible.

• Next steps

• Same experiment on other RGA tools to investigate reproducibility

23 May 2017

Confidential

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