vacuum metrology for science and industry · as mature vacuum techniques are, as ... task 2:...

Vacuum Metrology for Science and Industry

Karl Jousten, PTB, Berlin

1. Applications of vacuum and leak detection

2. Traceability and primary standards for vacuum and

low flow rates (leaks)

3. Secondary and reference standards

4. New developments and future challenges

VS4, Coventry, UK, October 2013, Karl Jousten 1

Applications of vacuum and leak detection


Nobel Prize 2013: Peter Higgs and Francoise Englert

Francois Englert (left) and Peter Higgs on July 4,

2012 at CERN

Image: Maximilien Brice/CERN

Break-up of a Higgs Boson, CMS detector,

LHC, CERN

Image: CERN



This was not possible without vacuum engineering:

LHC, 27 km, CERN

•3 huge vacuum systems,

for beam, for

superconducting magnets,

for helium distribution line:

104 km long, 15 000 m³

•2 times 27 km UHV < 10-8

Pa

• 250 000 welded joints

• 18 000 seals

• NEG coated walls

• 780 ion pumps

• 1084 Pirani and Penning

gauges

• 170 BAG

Vessel height 10.2m

Vacuum volume ~ 1330m3

Plasma volume ~ 837m3

Cryostat volume: 14 000m3

Hydrogen/isotopes: < 10-5 Pa

Other impurities: < 10-7 Pa

Total leak rate Torus: < 10-7 Pa m3/s

29 m

28.5 m

In the search for new energy: ITER



Microelectronic industry: no UHV/bake-out


MOCVD: Reactor for

ferroelectric films

Cluster tool


Industrial applications: CD/DVD metallization

Type Cathode Pumps Cycle-time

SINGULUS V

Focus 1

Focus Cathode 1 Turbo Molecular

Pump

2,7 s

SINGULUS V

Focus 2

Focus Cathode 2 Turbo Molecular

Pumps

1,5 s

SINGULUS V

Smart 1

SMART

CATHODE®

1 Turbo Molecular

Pump

2,5 s

SINGULUS V

Smart 2

SMART

CATHODE®

2 Turbo Molecular

Pumps

1,9 s



Introduction

Typical distribution of leaks in industrial products

mbar L/s

Majority of products

Geometrical leaks

Permeation leaks

Courtesy M. Bergoglio

Applications of partial pressure measurement:

• Gas purity (Semi)

• Residual gases

• In-situ analysis for reagent gases

• Outgassing rate measurement (EUV-Lithography)

• Sputter process control

• CVD monitoring, gas abatement analysis

• MBE source control

• End point detection (etching)

• Gas chromatography

EUV Lithography



1. For now 150 years vacuum technology is

one of the basics for physical experiments

and progress in industrial technology, from

high-tech-industry to food packaging.

2. This will persist (microelectronic-industry)

and grow (solar cells, EUV lithography,

nanotechnology, life sciences, new

materials, optical computer, quantum

computer)!

Turnover 2008: worldwide 6 Mrd $/a.

Conclusions from applications


3. As mature vacuum techniques are, as reliable vacuum measurement should be. All vacuum gauges need a calibration (at least by the manufacturer).

4. Fast processes are required

5. Leak testing: Traceability for low flow rates become more and more important.

6. Materials testing: Traceability and standardization of outgassing rate measurements become important.

7. Surface science/X-ray lasers: XHV is a niche, but also important

Conclusions from applications


Traceability and vacuum primary standards

What is traceability (Vocabulary International Metrology)?

Property of a measurement result whereby the result can be

related to a reference through a documented unbroken chain of

calibrations, each contributing to the measurement uncertainty.

As reference serve the primary standards:

Measurement standard established using a primary reference

measurement procedure, or created as an artifact, chosen by

convention.

Primary reference measurement procedure is used to obtain a

measurement result without relation to a measurement standard

for a quantity of the same kind (in the same range).


working standard

secondary standard

primary

standard

Calibration chain and uncertainties

ordinary vacuum gauge

22sec, calprimcert uuu

2sec,

22sec,sec callstcert uuuu 2

,2sec, calworkcertwork uuu

2,

22, calworklstcertworkwork uuuu

2,

2, calordworkcertord uuu

2,

22, calordlstcertordord uuuu

primu



Relative uncertainties of pressures in primary standards

2E-021E-02

5E-034E-03

2E-03

3E-04

5E-05

2E-05

6E-06 5E-06

1E-06

1E-05

1E-04

1E-03

1E-02

1E-01

1E+00

1E-10 1E-08 1E-06 1E-04 1E-02 1E+00 1E+02 1E+04 1E+06

p in Pa

Re

lati

ve

Un

ce

rta

inti

es

(k=

2)

Mercury Manometer

Continuous expansion Series expansion

p atm



Singapore

Mexiko

Fully developed primary standards down to high vacuum

National standards down to high vacuum



Secondary laboratories


Secondary labs

• Use secondary standards as reference (calibration by

comparison)

• Are accredited by a National Body (technical

accreditation of their calibration procedure)

• Work according to ISO 17025 and in vacuum in

addition according to ISO 3567 and 27893

• Distribute the scale more economically to the end user

• High

accuracy

• Good long

term stability

• Good

transport

stability

Reference gauges

Secondary and reference standards


10 5

10 2

10 -1

10 -5

10 -7

Rough vacuum Fine vacuum high vacuum Ultra high vacuum

p in Pa

Quartz Bourdon gauge

Resonance silicon gauge

Capacitance diaphragm gauge

Ionization gauge

Spinning rotor gauge

Lowest relative uncertainties for vacuum gauges and primary standards

.

1

0,2

0,05

0,02

0,05

0,1

0,01

0,005 0,0040,0040,003

0,002

0,001

0,1

0,01

0,02

0,01

0,02

1E-06

1E-05

1E-04

1E-03

1E-02

1E-01

1E+00

1E-10 1E-08 1E-06 1E-04 1E-02 1E+00 1E+02 1E+04 1E+06

p in Pa

Re

lati

ve

Un

ce

rta

inti

es

(k=

2)

Mercury Manometer

Continuous expansion Series expansion

p atm

Ionisation gauge Membrane

(mechanical)

Piston

QBS

CDG

SRGPirani

RSG

Secondary and reference standards




Leak rate threshold

Vacuum

Hood filled with known concentration of tracer gas

Test piece communicating with leak detector

Leak detector sensitive to tracer gas

pressure

Vacuum Test piece pressurized with tracer gas

Leak detector sensitive to tracer gas

Choose appropriate leak test method

Leak test (quantitative)

Standard leak (Validates your leak test)

Geometrical standard leak (capillaries)

Permeation standard leak

Written standards EN 1518, 1779, 13184, 13185,13192 ISO 3530, 27895 AVS practice (1992)



The standard leak enables the user

• To validate the applied method

• To verify and calibrate the reading of a leak detector

• Perform accurate measurements in-situ

Written standards require that

• The standard leak is calibrated (traceability to a primary standard)

• There is an uncertainty associated with the specified leak rate

Calibration/Traceability:

Reference leak

for leak detector

Secondary

standard leak

Primary flow

meter



Several types of gas flow measurement in vacuum metrology:

• pressure rise technique

• defined volume change, fixed pressure

• flowmeter (constant pressure, variable volume)

V

t

p

t

Vp

t

pVq pV



p=const

t

p

Gas Flow

C

V

Gas Inlet

V1

V2

V3

"Leak"

CDG

t

Vpq pV

RT

qq

pV

Temperature

stability !

PTB primary flowmeter (1E-8 Pa L/s…1E-2 Pa L/s)


Valve 1

Testleak

Valve 3

Enclosure T=const.

(necessary for permeation leaks)

Flowmeter

Valve 2

QMS


PTB measurement standard for vacuum standard test leaks

(1E-8 Pa L/s…1E-2 Pa L/s)


Testleak

Needle

CDG 133 Pa FS

CDG 133 kPa FS T1

T3

T2

T4

V1

V2

V3

V = 5.1 cm³

V = 6.1 cm³ Thermal insulation


PTB measurement standard for sniffer test leaks against atmosphere

Metre Convention (1875)

General Conference on Weights and Measures (CGPM)

every 4 years

International Committee for Weights and Measures (CIPM)

18 individuals elected by CGPM

10 Consultative Committees (CCs)

each chaired by a member of CIPM

Working Groups (WG)

Diplomatic Treaty

Governments of

member states

International

Organizations

National

Metrological

Institutes (NMI)

International Bureau of Weights and

Measures (BIPM, Sevres, France)

CIPM MRA (1999)



The Mutual Recognition Arrangement (MRA) of the CIPM

• to provide for the mutual recognition of calibration and measurement certificates issued by NMIs

by

• international comparisons of measurements, to be known as key comparisons, and as well supplementary international comparisons (http://www.bipm.org/kcdb)

• demonstration of competence by NMIs by publishing their calibration measurement capabilities

• establish an internationally accepted quality system in each NMI.





CCM.P-K12 (key comparison for leak rate measurement, 2012):

Transfer standards

Reservoir cannot

be refilled

Two helium permeation leaks:

4·10-11 mol/s (1·10-4 Pa L/s, 23°C) and 8·10-14 mol/s (2·10-7 Pa L/s),

no clogging, long-term stable, but decreasing rate

Temperature coefficient about 4%/K



Results of CCM.P-K12 (key comparison for leak rate measurement, 2012)

Dj

j

nu

DE

2

. mol/s10)0249.03746.4( 11

1,

q

New developments


High

pressure

volume

Low pressure

volume

Fast

opening

valve

Dynamic vacuum standard for rough vacuum at PTB

New developments : dynamic vacuum standard


Pressure step

Future developments


• On its way: Vacuum metrology for production environments (EMRP

IND12, 2011-2014)

– Work package 2 „Leak measurement and testing“

Task 1: Leak elements with defined geometry

Task 2: Improvement of the theory of flow in narrow ducts

Task 3: Leak elements performance (environmental conditions)

Task 4: Development of a practical guide on metrological performance of

leak detectors

Task 5: Feasibility study on alternative methods than mass spectrometer

leak detector to detect leaks within few seconds

Future developments


• On its way: EMRP IND12 – Work package 3 „Partial pressure and outgassing rate measurement “ Triggered by EUV-Lithography

• Written standards for vacuum gauge calibrations and perhaps design for ionization gauges

• Written standards for QMS calibration and outgassing rate measurements

• Furter developments of optical methods for vacuum measurement, also for leak testing

• Developments for harsh environments like Fusion (tritium, magnetic fields,…)

• XHV (but niche)

EUV-Lithography

Conclusion

• Traceable calibrations are more important than 20 years ago.

• Primary standards are available world wide.

• An international validation scheme ensures equivalence of vacuum gauge

and leak rate calibrations world wide.

• Reasonable secondary gauges for full vacuum range except for low HV

and UHV.

• Written standards are in progress and shall transform our present

knowledge into long-lasting practical solutions. Need to be extended for

partial pressure and outgassing rate measurement.

Dome of the Reichstag in Berlin

vacuum metrology for science and industry · as mature vacuum techniques are, as ... task 2:...

Documents