Pfeiffer Vacuum QMG 422 User manual

Operating Instructions
Incl. Declaration of Conformity
BG 805 983 BE (0112) 1
QMG 422 Analyzers

2BG 805 983 BE (0112) QMA4x0.oi
In all communications with Pfeiffer Vacuum, please specify the information on the
product nameplate.
For convenient reference copy that information into the space provided below.
Typ:
No:
F-No:
Pfeiffer Vacuum, D-35614 Asslar
This document applies to the QMA 400, QMA 410, QMA 430 with Faraday cup or
90° off-axis SEM and Faraday cup and with the ion sources described in this
document.
If not indicated otherwise in the legends, the illustrations in this document corre-
spond to the QMA 400 with 90° off-axis SEM. They apply to other types by analogy.
The short designation "QMA" is used for the QMA 400, QMA 410 and QMA 430.
The short designation "QMH" is used for the QMH 400 and QMH 410.
In contrast to the operating instructions for the QMG 422, these instructions follow
the same conventions as the Pfeiffer QuadStar™ 422 operating instructions. The
parameters are marked with quotation marks ("…") e.g. "Resolution".
We reserve the right to make technical changes without prior notice.
The QMA 400, QMA 410 and QMA 430 Analyzers are used for gas analysis in high
vacuum.
They are part of the QMG 422 mass spectrometer system and may only be used in
connection with equipment belonging to that system.
The operating instructions of all system components must be strictly followed.
Product Identification
Validity
Illustrations
Designations
Technical changes
Intended Use

BG 805 983 BE (0112) QMA4x0.oi 3
Contents
Product Identification 2
Validity 2
Intended Use 2
1 Safety 5
1.1 Symbols Used 5
1.2 Personnel Qualifications 5
1.3 General Safety Instructions 5
1.4 Liability and Warranty 6
2 Description 7
2.1 Design 7
2.1.1 Ion Sources 8
2.1.2 Mass Filter 8
2.1.3 Secondary Electron Multiplier 9
2.2 Versions 10
2.2.1 Cathode Materials 10
2.2.2 Electron Collimation Magnet 11
2.2.3 90° Deflection 11
2.2.4 Faraday Cup 12
2.2.5 Isolated Design 12
2.2.6 Vacuum Annealed QMA 13
2.2.7 Extraction Hood 13
2.2.8 Beam Deflection Device 13
2.2.9 Differential Pumping 13
3 Technical Data 14
4 Installation 17
4.1 Preparation 17
4.1.1 Installing the Electron Collimation Magnets 20
4.2 Installation 21
4.3 Gas Inlet System 22
4.4 QMH 400/410 22
4.5 EP 422 22
4.6 CP 400 23
4.6.1 Removing / Installing the SEM Connector Plate 23
4.7 Mounting the Protective Tubes 23
4.8 Cabling 23
5 Operation 24
5.1 First Time Operation 24
5.2 High Temperature Operation 25
5.3 Baking the Analyzer 25
5.3.1 Removing the Connector Plates 26
5.3.2 Mounting the Connector Plates 26
5.4 Assessing the Sensitivity 26
5.5 Secondary Electron Multiplier SEM 27
5.5.1 Contamination 27
5.5.2 Low Partial Pressures 27
5.5.3 Gain Factor 27
5.6 Surface Ions 28
5.7 Degas 28

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6 Optimization 29
6.1 Recommended Operating Modes 29
6.2 Test Gas 30
6.3 Ion Source Parameters 31
6.3.1 Emission 31
6.3.2 Protection 31
6.3.3 V1 IonRef 31
6.3.4 V2 Cathode 32
6.3.5 V3 Focus 32
6.3.6 V4 Field Axis 32
6.3.7 V5 Extraction 33
6.3.8 V8 Reserve 33
6.3.9 V9 Wehnelt 33
6.4 V6 / V7 Deflection 33
6.5 Resolution 34
6.6 RF Cable Polarity 34
7 Ion Sources 35
7.1 Axial Ion Source 35
7.2 Crossbeam Ion Source 37
7.3 Grid Ion Source 41
7.4 Two Lens Ion Optics 43
7.5 Crossbeam Ion Source With Two Lens Ion Optics 46
7.6 Three Lens Ion Optics 48
7.7 Crossbeam Ion Source With Three Lens Ion Optics 51
8 Maintenance and Spare Parts 54
9 Disposal 54
Appendix 55
A: Literature 55
Declaration of Contamination 56
Declaration of Conformity 57
For cross-references within this document, the symbol (→ XY) is used, for cross-
references to other documents, the symbol (→[Z]).

BG 805 983 BE (0112) QMA4x0.oi 5
1 Safety
DANGER
Information on preventing any kind of physical injury.
WARNING
Information on preventing extensive equipment and environmental damage.
Caution
Information on correct handling or use. Disregard can lead to malfunctions or
minor equipment damage.
Skilled personnel
All work described in this document may only be carried out by persons who
have suitable technical training and the necessary experience or who have been
instructed by the end-user of the product.
• Adhere to the applicable regulations and take the necessary precautions for the
process media used.
• Consider possible reactions between the materials (→ 14) and the process
media.
• Consider possible reactions of the process media due to the heat generated by
the product.
• Post the warning signs required by the national and local regulations at the
appropriate places.
• If toxic or flammable gases are measured with the QMA, the exhaust gases
must be treated in accordance with the applicable regulations.
• Adhere to the applicable regulations and take the necessary precautions for all
work your are going to do and consider the safety instructions in this document.
• Follow the instructions and consider the data given in the documentation of all
system components.
1.1 Symbols Used
1.2 Personnel Qualifications
1.3 General Safety
Instructions
Process media
Safety measures

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• Before beginning to work, find out whether any components are contaminated.
Adhere to the relevant regulations and take the necessary precautions when
handling contaminated products.
• Products returned to Pfeiffer Vacuum for service or repair should preferably be
free of harmful substances (e.g. radioactive, toxic, caustic, or microbiological).
Do always enclose a completed and signed declaration of contamination
(→ 56).
• Adhere to the forwarding regulations of all involved countries and forwarding
companies.
•
• •
• Communicate the safety instructions to all other users.
Pfeiffer Vacuum assumes no liability and the warranty becomes null and void if the
end-user or third parties
• disregard the information in this document
• use the product in a non-conforming manner
• make any kind of interventions (modifications, alterations etc.) on the product
• use the product with accessories, options, and add-ons not listed in the corre-
sponding product documentation.
The end-user assumes the responsibility in conjunction with the process media
used.
Caution
Caution: inappropriate use
Inappropriate use of the product may lead to contamination or de-
struction of the cathode or secondary electron multiplier.
Adhere to the instructions in this manual to prevent such damages,
which are not covered by the warranty.
Training
Pfeiffer Vacuum offers application, operating and maintenance courses for the
best use of this product. Please contact your local Pfeiffer Vacuum represen-
tative.
Contamination
Communication of safety
instructions
1.4 Liability and Warranty

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2 Description
Chapter "Overview" in [1] shows the complete system and contains short de-
scriptions of the individual components.
The analyzers QMA 400, QMA 410, and QMA 430 are the sensors of the QMG 422
mass spectrometer system.
A quadrupole analyzer consists of:
• ion source and/or ion optics
• mass filter with rod system
• ion detector (SEM and ion deflection unit with Faraday or Faraday only)
• housing with flanges
Axial
Crossbeam (CB)
CB gas tight
CB gas tight with two
gas admission ports
CB with molecular
beam device
Grid
Two lens
ion optics
CB + two lens
ion optics
Three lens ion optics
CB + three lens ion optics
Ion sources Mass filter
Deflection unit
SEM
Housing
QMA with Faraday cup
Faraday cup
Faraday cup
Connection flange
QMA with 90° off axis SEM
Connection flange
2.1 Design

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High mechanical precision combined with optimum cooperation between the ion
source and rod system, forming the ion optical unit, yield high resolution and
transmission with low mass discrimination.
The high resolution and wide mass range make this instrument suitable for analy-
tical measurement problems.
A variety of designs, with Faraday cup or with 90° off-axis SEM plus Faraday cup,
as well as the ample choice of ion sources and ion optics ensure an optimum ad-
aptation to the individual measurement problem.
The open design and low degassing rate of the analyzers, conceived as immersing
systems, allow exact partial pressures analyses from the high vacuum up to the
extreme ultra high vacuum range (UHV).
The ionization is achieved by electron impact. Electrons are thermally emitted by a
cathode and focused by electrical extraction fields so that they reach the ionization
area.
The ionization process is crucial for the overall quality of the analysis. Errors
occurring in this part of the process are virtually irreversibly. Therefore, the ion
source must be selected very carefully.
For more details on the individual ion source types: → 34 ff.
Closed (gas tight) ion sources allow gas analyses with a minimum contribution from
the residual vacuum. They are virtually fractionation-free, have a high signal to
noise ratio, a low gas consumption, and a small time constant.
Vacuum ion optics are used for focusing ions which are produced independently of
the QMA (e.g. plasma technology, laser, SIMS, thermal desorbed ions) to the mass
filter.
The proper material selection and very precise manufacturing methods ensure a
high measure of linearity and reproducibility.
QMA 430: For masses up to 300 amu the economic 8 mm rod system made of
stainless steel can be used.
QMA 400: For higher mass ranges as well as optimum stability and reproduci-
bility, 8 mm molybdenum rods are used because of the superior elec-
trical and thermal properties of the material.
QMA 410: The 16 mm molybdenum rod system is used for this analyzer.
At constant frequency, the transmission increases as a function of the
rod diameter while the mass range narrows. In parallel, the impact of
the filtered ions on the rod surfaces and thus the contamination of the
rod system is reduced.
2.1.1 Ion Sources
2.1.2 Mass Filter

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The secondary ion multiplier with its 17 discrete stages and focusing dynode
geometry is a fast ion current amplifier between the quadrupole filter and the
preamplifier.
The high gain of the SEM allows to operate the succeeding electrometer amplifier
with a lower gain. The time constants become thus smaller, permitting measure-
ment of fast signals with low intensity.
Positive ions are detected in normal operation with a negative high voltage applied
to HV- and ground connected to HV+ of the secondary electron multiplier SEV 217.
The operating voltage "SEM Voltage" determines the gain and is at the same time
the energy for additionally accelerating the ions.
HV- HV+
EP
HV420
HV421
-+
0...-3.5kV
EP422
For detection of negative ions, +3.1 kV supplied by the HV 421 are applied to the
first dynode (HV-) (-3.1 kV for positive ions). This means that up to 6.6 kV are
applied to the HV+. In this case, the ion counter must be used instead of the
electrometer amplifier.
HV- HV+
CP422
+3.1kV HV421
-+
0...-3.5kV
In counting mode, ions of 1 pulse per 10 s (which corresponds to an ion current of
10-20 A) up to 107pulses per s can be detected.
In this case, the energy for additional acceleration is independent of the operating
voltage and thus from the gain setting.
2.1.3 Secondary Electron
Multiplier
SEV 217
Negative ions

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The SEV 218 corresponds to the SEV 217. Additionally, it has a conversion
dynode, which is separate from the dynode chain and fed by an invariable high
voltage source (-6.3 kV at the CD connector of the HV 421), which is independent
of the operating voltage of the secondary electron multiplier.
HV- HV+
EP
CD
...-6.3kV
HV421
-+
0...-3.5kV
CD
EP422
The gain of the SEM can be selected independent of the additional acceleration.
The high additional acceleration allows for a strong reduction of possible mass
discrimination due to the conversion. The independent setting of conversion rate
and gain has also considerable advantages for ratio measurements (e.g. isotopes)
with high dynamics.
The ion sources can be equipped with cathodes (filaments) which are best suited
for the planned application. Certain cathode materials are not available for all
source types →[4] "Spare parts lists".
In contrast to tungsten (W), rhenium (Re) does not form any stable carbides, since
no CO2cycle as known with W takes place. In addition, Re is not embrittled by re-
crystallization.
The vapor pressure of Re is approximately 50 times higher than that of W, and the
filament life is accordingly shorter. Getter effects may occur due to the evaporation
rate.
Tungsten is used when the higher vapor pressure of rhenium is undesirable, when
a long filament life is required, or when the advantages of Re are not important to
the application.
Since yttrated iridium (YOx-Ir) does not form oxides, it is quite insensitive to air in-
rushes.
The emission temperature of yttrated iridium cathodes is lower than that of Re and
W cathodes. Reactions with residual gas are weaker because the ion source tem-
perature remains low.
The contamination may be stronger when substances with a low vapor pressure
are admitted.
SEV 218
2.2 Versions
2.2.1 Cathode Materials
Rhenium
Tungsten
Yttrated iridium

BG 805 983 BE (0112) QMA4x0.oi 11
The crossbeam ion source can be equipped with a magnet unit. This is recom-
mended for applications in high mass ranges, for molecular beam detection, and in
the QMA 410 for separating He and D2.
The magnet increases the electron density in that part of the volume of the ion
source, from which ions can be easily focused into the mass filter.
The magnet increases the real path length of the electrons and thus the ion yield.
This results in higher sensitivity and better injection conditions. In addition, the
magnet prevents the majority of the electrons from hitting critical locations of the
formation area. However, the linearity (measurement signal vs. pressure) is
reduced.
Analyzers with integrated collimation magnets may only be baked to 300°C.
The 90° off-axis arrangement of the secondary electron multiplier has a very low
signal background because the electrostatic 90° deflection prevents fast or excited
neutrals and photons from hitting the SEM.
There are two deflection versions:
Normal version (axial, crossbeam, grid ion source, possibly ion optics).
The inner deflection plate is on potential V6 "Deflection", the outer deflection plate
is directly connected to the Faraday cup and electrometer amplifier EP1 and is thus
on ground potential. If there is no EP1 in the configuration, a shorting connector is
used.
EP1
EP2
Deflection unit Faraday cup
V6
Deflection
SEM
2.2.2 Electron Collimation
Magnet
2.2.3 90° Deflection
One deflection voltage

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Special versions (mostly with ion optics, →enclosed diagram of the QMA).
The inner deflection plate is on potential V6 "DEFI", the outer deflection plate is on
potential V7 "DEFO". The Faraday cup is isolated from the deflection plate and
connected to the electrometer amplifier EP1.
EP1
EP2
V7
DEFO
V6
DEFI
Depending on the application, the deflection of this version is more efficient, as
accelerating potentials are applied to both deflection plates.
In Faraday operation, the sensitivity is slightly lower than with one deflection volt-
age because less ions reach the Faraday cup.
Faraday cup operation (QMA with Faraday or SEM types operated in Faraday
mode) reduces system related conversion errors of the SEM (e.g. mass discrimi-
nation).
Faraday operation can also be used for error detection.
The drawback of Faraday operation is the lower sensitivity, which requires a higher
gain and thus limits the response speed.
Some versions (e.g. with ion optics) have an isolated design i.e. the filter housing
and thus ion optics, mass filter, and deflection unit are isolated from ground. A
potential can be applied to the filter housing in order for ions formed close to the
ground potential (e.g. in a plasma) to be transferred through the fringe fields with
sufficient velocity.
These versions may have an additional SHV connector for the corresponding volt-
age on the QMA
• BIAS as input
• TARGET as output for SIMS analyzers
DANGER
Caution: shock hazard
The voltages of the IS 420 and the additional voltage can be extremely
hazardous.
Consider the technical specifications of the IS 420 (→[1]) and use
only properly made cables.
Two deflection voltages
2.2.4 Faraday Cup
2.2.5 Isolated Design

BG 805 983 BE (0112) QMA4x0.oi 13
The QMA with the vacuum annealed grid ion source has a very low degassing and
desorption rate (< 10-10 mbar l/s).
For extracting ions from a plasma, an extraction hood can be
installed.
As the versions with extraction hood are customized, a cor-
responding description is enclosed with the test protocol.
Further information →[3]
For detecting ions which are not focused in the axis of the
analyzer, a beam deflection device is installed. It is based on
a sector field and can be combined with an extraction hood.
There is a variety of possible detection angles.
As the versions with beam deflection device are customized,
a corresponding description is enclosed with the test protocol.
If the pressure of the gas or plasma to be analyzed exceeds the admissible maxi-
mum pressure of the QMA, the analyzer is differentially pumped with a turbo-
molecular pump.
Turbo
molecular
pump
The T-piece of the housing is replaced with a crosspiece. Diaphragm glands having
a much smaller conductance than the orifice are used as seals.
The pressure drops because of the limited conductance of the entrance orifice, the
extraction hood, or the beam deflection device.
The pressure range can be expanded with a dual-stage differential pump system
(process pressures up to 1 bar can be reached).
2.2.6 Vacuum Annealed QMA
2.2.7 Extraction Hood
2.2.8 Beam Deflection Device
2.2.9 Differential Pumping

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3 Technical Data
Maximum admissible overpressure 2 bar (absolute)
Maximum operating pressure
with Faraday
with SEM
1×10-4 mbar in the ion source
1×10-5 mbar in the ion source
Smallest detectable partial pressure
with Faraday
with 90° off-axis SEM and ion
counter electronics
<10-11 mbar
<10-15 mbar
Sensitivity for air
with Faraday
with SEM
>3×10-4 A/mbar
>200 A/mbar
Applies to QMA 400 without SEM, crossbeam ion source with magnet, emission
1 mA, ∆M10 = 1 u 1
Refer to the test protocol for your individual configuration.
QMA 400 QMA 410 QMA 430
Rod diameter
Rod length
Rod material
ø 8 mm
200 mm
molybdenum
ø 16 mm
300 mm
molybdenum
ø 8 mm
200 mm
stainl. steel
Gain (new)
Operating voltage
Bias voltage
Number of stages
Voltage divider
Max. admissible output voltage
Max. bakeout temperature
of dynode material
>108at 3.5 kV
1 … 3.5 kV
max. ±3.2 kV at SEM–
17
18 MΩ
10-5 A
400 °C
Cu-Be
As SEV 217, however, with separate
conversion dynode CD
CD voltage max. – 6.3 kV
QMA 400 DN 63 CF
QMA 410 DN 100 CF
QMA 430 DN 63 CF
Without cables and connector plates
With electron collimation magnet
With cables and connector plates
With preamplifier or electrometer
max. 400 °C
max. 300 °C
max. 180 °C
max. 50 °C
Stainless steel, Mo, Al2O3, Cu-Be, Ni, W, Re, yttrated iridium
1Peak width = 1 u on 10% of peak height
Overpressure
Vacuum
Sensitivity
Mass filter
SEV 217
SEV 218
Connection flange
Bakeout temperatures
Materials in vacuum

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Rhenium >2,000 h
Tungsten ]10,000 h
Yttrated iridium >10,000 h
Valid for p <10-5 mbar, emission 1 mA and electron energy ≥70 eV in a non
oxidizing atmosphere
→ 57 Declaration of conformity
FARADAY
90°OFF AXIS
ABC
D
E
F
E
133
G
133
ABC
E
G
(The illustrations are not to scale.)
90° off-axis Faraday
QMA 400 QMA 430 QMA 410 QMA 400 QMA 410
A244 244 245 104 245
B162 162 267.5 223 269.2
D251 251 251 252
EDN63CF DN63CF DN100CF DN63CF DN100CF
FDN63CF DN63CF DN63CF --- ---
Gø63 ø63 ø100 ø63 ø100
Weight 10.7 kg 10.7 kg 17.2 kg 2.9 kg 6.5 kg
Filament life
Standards
Dimensions and weight

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Ion sources C H
Axial 26 ---
Crossbeam (CB) 35.5 23.5
CB gas tight 1) 48 2) 23.5
Grid 27 ---
2 lens ion optics 17.5 ---
CB with 2 lens optics 43.5 23.5
3 lens ion optics 129 ---
CB with 3 lens optics 171 23.5
1) With axial gas connection
2) Without gas admission line (outer diameter of gas admission line 3 mm)
Gas connections
CB gas tight with 1 axial connection Bore in glass ceramic
for tube with outer diameter 3 mm
CB gas tight with 2 lateral connec-
tions
2 gas admission lines according to drawing
BK 355 107 -Z are enclosed
CB with molecular beam device DN16CF with Swagelok fitting ø ¼"

BG 805 983 BE (0112) QMA4x0.oi 17
4 Installation
DANGER
Caution: hazardous electrical voltages
Hazardous voltages up to 600 V are applied to the QMA.
Make sure the QMA, the vacuum chamber, and the whole system are
always correctly connected to ground.
If accidental contact to the QMA is possible when the vacuum system
is opened, additional protective measures have to be taken, for in-
stance:
• Mechanical protection against accidental contact
• Forced disconnection of the QMS 422 from the mains power
source through door contact
DANGER
Caution: hazardous electrical voltages
Under unfavorable conditions (arcs, plasma, vacuum problems), volt-
ages up to 600 V can be fed to other equipment in the vacuum cham-
ber (e.g. gauges).
If there is a possibility that such pieces of equipment become sources
of shock hazard (consider also the conductors and connected equip-
ment!) they must be arranged or protected in such a way that any risk
of accidental contact, arcs, or flow of charged particles is excluded.
DANGER
Caution: hazardous external voltages
Under unfavorable conditions (arcs, plasma, vacuum problems), volt-
ages of other equipment installed in the vacuum system (e.g. ioniza-
tion gauges, plasma sources, electron beam evaporators etc.) can be
supplied to the QMA. Open connectors, connected equipment and
cables are potential sources of shock hazard.
If there are such potential sources of shock hazard in the vacuum
system, protective measures have to be taken (layout, grounding,
shielding etc.) to prevent such influences.
The QMS 422 must also be permanently connected to ground (not via
a connector). The contact is inside, behind the mains plug. Make a
grounding conductor of yellow/green stranded copper wire if neces-
sary:
• 2.5 mm2if mechanically protected (according to
DIN VDE 110 T540)
• 4.0 mm2if not mechanically protected
Consider the specific standards of your system.
In most cases, the mounting orientation can be chosen irrespective of the function.
Select the mounting orientation which is best suited to the arrangement of the radio
frequency generator, QMH and cables (→[2]).
The position of the ion source should be selected according to the requirements of
the analytical task. For instance, reliable residual gas analysis is not possible if the
analyzer is connected to the measuring chamber only via a tube with a small dia-
meter.
4.1 Preparation
Mounting orientation

18 BG 805 983 BE (0112) QMA4x0.oi
Prepare the gas inlet system (if necessary) in order to ensure easy connection to
the ion source.
The crossbeam ion source might have to be aligned with the gas inlet system. In
that case mark the correct mounting orientation (direction of the arrows) on the
flange of the QMA and the system.
• Place the analyzer on the edge of a workbench (→illustration)
• Unfasten the locking screw on the mounting plate with a screw driver No. 6
• Slide the mounting plate on the analyzer flange.
• Position the mounting plate so that you can easily hold the analyzer and intro-
duce it into the vacuum system in its correct orientation (→ 22).
Locking screw
Mounting plate
• Tighten the locking screw.
Gas inlet system
Installing the mounting plate

BG 805 983 BE (0112) QMA4x0.oi 19
• Mount the assembling trestle
to a stable workbench.
• Insert the analyzer with the
installation plate into the
assembling trestle.
Only for QMA 400/430 without
SEM:
• Remove the three screws.
• Remove the protective tube.
Using the assembling trestle
Removing the protective tube

20 BG 805 983 BE (0112) QMA4x0.oi
Caution
Caution: dirt sensitive area
Touching the product with bare hands causes distortion of the meas-
urement results.
Always wear clean, lint-free gloves and use clean tools when working
in this area.
• Carefully remove the transport
protection and keep it for later use.
• Check the inside for damages and
short circuits of the wiring.
The magnet unit of the crossbeam ion source is delivered in a separate package. If
the conditions for use are fulfilled (→ 11 and 40) mount it on the ion source as
described below.
Caution
Caution: dirt sensitive area
Dirt causes malfunctions or failures.
Always wear clean, lint-free gloves and use clean tools when working
in this area.
Caution
Caution: The magnets are aligned.
If the magnets are detached from the installation plate, correct align-
ment is no longer possible.
Do not detach the magnets from the installation plate!
Removing the transport
protection
4.1.1 Installing the Electron
Collimation Magnets