BEST KNOWN METHODSTranspector® XPR3 Gas Analysis System

DESCRIPTIONThe Transpector XPR3 is a third-generation, quadrupole-based
residual gas analyzer that operates at PVD process pressures andis the first process monitor with an Electron Multiplier (EM) that canoperate at 10 mTorr operating pressures. The XPR3 does not
require the large differential pumping system normally required for
PVD process monitoring. The XPR3 can operate up to 20 mTorr,and it is linear at pressures up to 10 mTorr. The XPR3 measures
major components and impurities common in a process with a
10 ppm detection limit.
Using these recommended Best Known Methods will provide youwith a reliable Transpector XPR3 for process monitoring a highpressure application.

XPR3 APPLICATIONSThe XPR3 utilizes a High Pressure MicroChannel Plate Electron
Multiplier (HPEM). The HPEM can be used at lower pressures,such as background pressures, and it can also be used at higher
pressures, such as process pressures.
The XPR3 is typically used for process monitoring of PVD
applications. These applications normally operate in the mTorr
range with backgrounds from 1e-6 to 1e-9 Torr. While the XPR3
can be used for other applications where the process pressure isless than 10 mTorr, precautions should be used. Applications thathave high levels of hydrocarbon contamination or a significant
amount of fluorines, chlorines or halogens are inappropriate for the
XPR3.

reaching the ion source plate, which prevents any material from
depositing on the XPR3 sensor. A heating jacket is provided with
the XPR3 package and should be installed over the interlock
weldment such that the cable is oriented as seen in Figure 1.
Tool

Interlock Weldment
IPN 914-416-G1

7.2 in.(18 cm)
ManualTranspector XPR 3

8.3 in.(21 cm)
Air Operated

7.7 - 8.8 in.
(19.6 - 22.3 cm)

Pirani Gauge
IPN 918-401-P1

Heater

15.3 in. (38.7 cm)o

The 90 Isolation Valve islocated between the Tool
Chamber and the XPR3
(INFICON supplied option)

Figure 1
Once the XPR3 sensor, electronics module, valve, and Pirani
gauge are installed, the valve should be opened to allow the XPR3
to obtain high vacuum. It is strongly recommended that the XPR3
be kept under high vacuum conditions for at least eight hours
before the filament is turned on. It is also recommended that the
XPR3 be baked out with the supplied heating jacket (which
operates at 150 °C) for a period of at least eight hours. This eighthour minimum bake out is required to reduce residual water vapor
levels that may be higher due to local surface outgassing effects.
These recommendations should be followed whenever the XPR3
sensor is exposed to atmosphere for long periods of time and willserve to increase sensor life.

PHYSICAL INSTALLATIONThe XPR3 package includes an interlock weldment approximately
3.6" (91.44 mm) long with a VCR connection tube for the Pirani
gauge. The Pirani gauge is used for turning the XPR3 filament off
above 20 mTorr and optionally turning the filament back on atpressures below the turn off point.
The XPR3 sensor mounts within the interlock weldment. The
weldment must be mounted to the process chamber via a 90° valve(or mitered elbow). This prevents any line of sight plasma from

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Transpector XPR3 Best Known Methods

PIRANI SET-UP
Clicking first on the XPR3 icon from the TWare32™ main screen toreach the Sensor Properties screen, and then selecting the TSPUser Settings tab will display the Pirani gauge set points. The
Pressure Interlock Functions dialog is shown in Figure 2. The
Emission OFF Pirani Interlock function is automatically enabled
and cannot be disabled. The default (and maximum) value foremission off is 20 mTorr. The Pirani Auto Emission ON is
disabled by default, but can be enabled by checking the box andassigning a value less than or equal to 3.00e-3 Torr.

LEAK DETECTION
Using TWare32, there is no recipe required for operating in Leak
Mode. Select the Leak Mode icon as pictured above to default tosampling Helium (Mass 4) over time. When leak checking avacuum system that has a pressure of 1x10-5 Torr or lower, the
HPEM should be used. The HPEM voltage that is necessary isbased on the level of the leak that you are searching for. Adjust the
HPEM voltage so that the Helium (Mass 4) signal can be observed,
but do not exceed an intensity of 1e-7 amps.

RECIPE GENERATION

Figure 2

USING THE XPR3
Once the sensor has been conditioned, by baking it out and thenkeeping it under vacuum, the emission can be safely turned on. At
this point, typical uses for the XPR3 would be leak detection,
background monitoring, and process monitoring. The following arerecommended parameters when operating the XPR3 in any ofthese applications.
These settings are reached from the Recipe Editor by choosing
Recipe Editor >> Sensor State >> Advanced Functions (seeFigure 3).
Baseline should be enabled by checking the box Baseline
Subtract On and choosing Spectra as the Baseline Type.
Use the default Subtraction Masses of 9, 23, 33, and 47.
Linearization should always be ON, by checking the box. Use
the Factory determined values that have been programmed
into the Transpector firmware.

Using the XPR3 for background monitoring or process monitoringis accomplished by creating and running a recipe. The XPR3 user
can generate these recipes, or sample recipes can be obtained
from INFICON. The recipe file sizes are rather small (about 1 Kb)
and can easily be e-mailed if desired. Please contact INFICON byphone at (315) 434-1128 or by e-mail at reachus@inficon.com.

BACKGROUND MONITORING
BEST PRACTICAL DETECTION LIMITSBKG-BEST.RCP
For acquiring a spectrum where the full mass range is desired, therecipe parameters should be:Spectrum Scanning

Mass Range 0-50

1 point per AMU

Dwell time = 128 ms



EM ON



EM voltage set for 300 gain The EM voltage is set for 300 gainat the Factory, and may require periodic adjustment
depending on the current levels delivered to the EM.

Electron Energy = 40 eVPeak Lock should always be OFF, by not checking the box.

The above recipe will provide the best results for backgroundmonitoring, but will take approximately 11 seconds for one scan.
See Figure 4 for typical background results.

Figure 3

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Transpector XPR3 Best Known Methods

CAUTION
Do not scan over any peak with the EM ON
that produces ion currents in excess of
1e-7 amps. For example, do not scan over
Mass 40 Argon in a PVD process involving
Argon gas since this mass will produce
large peaks. Use Mass 36 Argon isotope asa safe alternative. Scanning over any large
ion currents for extended periods of time
will damage the Electron Multiplier andsubstantially shorten its lifetime.
This recipe will take about 3 seconds per scan and will produce
results similar to those shown in Figure 5. Peaks for hydrocarbons
can be added at mass 15 and/or 42.

Figure 4

BACKGROUND MONITORING
FAST RESULTS - BKG-FAST.RCP
Faster scanning can be accomplished, but detection limit andaccuracy will be sacrificed. For faster scanning, the dwell time canbe reduced to 32 ms. This will lower the scan time to about 4
seconds.

PVD PROCESS MONITORING WITH
ARGON PROCESS GAS:BEST RESULTS - PRO-BEST.RCP
Since it is assumed that speed is very important in monitoring
various gases during the process, Selected Peaks mode should be
used instead of Spectrum Scanning. The recipe parameters
should be:Electron Energy = 40 eV

EM ON with a gain set to 300. The EM voltage is set for 300
gain at the Factory, and may require periodic adjustment
depending on the current levels delivered to the EM.

While the masses to be sampled are customer selectable, thefollowing masses and dwell times are recommended for a typical
PVD application involving Argon process gas: (see Table 1).
Table 1 Recommended Masses and Dwell Times for
Typical PVD Applications

Figure 5

PVD PROCESS MONITORING WITH
ARGON-NITROGEN PROCESS GAS
For metal-nitride processes, the presence of nitrogen can also
generate high ion currents at Mass 28. For these processes,
alternate recipes are recommended with peaks listed in Table 2.
Table 2 Recommended Peaks for Metal-Nitride PVD Process
Using Argon-Nitrogen Gases
Mass

Species

Dwell

Multiplier

MassSpecies

Dwell TimeMultiplier

2

H2

32 ms

1

2

H2

32 ms

1

14

N2 / CO128 ms

25 **

18

H2O

128 ms1

18

H20

128 ms128

N2 / CO128 ms1

32

O2

128 ms1

32

O2

128 ms

1

36

Ar36

32 ms

297

36

Ar36

32 ms

297*

44

CO2

128 ms1

44

CO2

128 ms1

Hydrocarbons

128 ms1

Optional:
15 or 42

Hydrocarbons

128 ms1

Optional:
15 or 42

* Multiplier is derived from the natural abundance of Ar36 in
Argon gas: 100/.0337 = 297** Default value. Sensor specific value can be found by FC
measurement of N2: Multiplier = I(28)/I(14)3 of 6

Transpector XPR3 Best Known Methods

PREVENTIVE MAINTENANCE
The XPR3 sensor has yttria-coated iridium filaments with a defined
lifetime as well as a high-pressure electron multiplier that may
degrade over time.

CAUTION
Do not scan over any peak with the EM ON
that produces ion currents in excess of
1e-7 amps. For example, do not scan over
Mass 28 Nitrogen in a PVD process
involving Argon-Nitrogen gas since thismass will produce large peaks. Use Mass
14 Nitrogen isotope as a safe alternative.
Scanning over any large ion currents forextended periods of time will damage theElectron Multiplier and substantiallyshorten its lifetime.

XPR3 FILAMENTThe XPR3 filaments should last a minimum of 4000 hours when
following these Best Known Methods. It is strongly recommended
that the filaments be replaced after 4000 hours of operation(approximately six months of continuous operation).

CAUTIONPVD PROCESS MONITORING WITH
ARGON-OXYGEN PROCESS GAS
For metal-oxide processes, the presence of oxygen can also
generate high ion currents at Mass 32. For these processes,
alternate recipes are recommended with peaks listed inTable 3.
Table 3 Recommended Peaks for Metal-Oxide PVD Processes
Using Argon-Oxygen Gases
Mass

Species

Dwell

Multiplier

2

H2

32 ms

1

16

O2

128 ms15 ***

18

H20

128 ms128

N2 / CO128 ms

1

36

Ar36

32 ms

297

44

CO2

128 ms1

Optional:
15 or 42

Hydrocarbons

128 ms1

If the filaments are not replaced and areallowed to burn out, coating from thefilament could contaminate the ion source
plate and create electrical shorts
preventing operation with a new set offilaments.
The yttria-coated filament kit (INFICON part number 914-022-G2)
is field replaceable. Replacement instructions are included in thefilament kit and in the Transpector XPR3 Operating Manual(INFICON part number 074-378).
To determine how many hours the filaments have been
operational, click on the XPR3 icon from the TWare32 main screen
to reach the Sensor Properties screen and then select theMaintenance tab. The information displayed is shown in Figure 6.

*** Default value. Sensor specific value can be found by FC
measurement of O2: Multiplier = I(32)/I(16)Figure 6

CAUTION
Do not scan over any peak with the EM ON
that produces ion currents in excess of
1e-7 amps. For example, do not scan over
Mass 32 Oxygen in a PVD process
involving Argon-Oxygen gas since thismass will produce large peaks. Use Mass
16 Oxygen isotope as a safe alternative.
Scanning over any large ion currents forextended periods of time will damage theElectron Multiplier and substantiallyshorten its lifetime.

HIGH PRESSURE ELECTRON MULTIPLIER
Since the HPEM is used at background and process pressures,the EM hours will mirror those of the emission hours. The HPEM
gain may degrade over time and it is recommended to replace theEM when the EM voltage can no longer be adjusted to achieve a
300 gain. It is expected that the HPEM will last longer than one
year, when used continuously.
The HPEM degrades from monitoring high ion currents. Figure 7
shows estimated age for the EM as a function of process pressure
for common gas mixtures and for monitoring different peaks. The
plot highlights the increased lifetime advantage of measuring therecommended mass peaks. [These are estimates based on test
data. Individual HPEMs may have different lifetimes depending on
usage history.]

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Transpector XPR3 Best Known Methods

MASS SCALE TUNING AT BASE PRESSURE
Mass scale tuning can be done at base pressure using thebackground peaks of water vapor (18 AMU) and Nitrogen (28AMU). The following procedure should be used to check peaklocation and peak widths at mass 18 and mass 28 and to makeadjustments as needed.

CAUTION
Do not attempt to remove masses 1, 2, 4, or
86 AMU from the Tune Table or adjust theresolution at these masses.

Figure 7

MASS SCALE TUNING
Another part of preventative maintenance is checking thefunctional operation of the XPR3. This includes the mass position
and mass resolution of the instrument. While this mass scaletuning is accomplished in a similar fashion to any otherTranspector, the XPR3 does have some slightly different values forpeak width adjustment.
The grid on the right of the screen shown in Figure 8 shows the
typical masses from a factory calibration gas mixture. The
TWare32 Operating Manual (INFICON part number 074-334)
provides details on how to tune the resolution and mass position
for any Transpector and the following sections are to be used formass scale tuning in the field.

1.

Open the Tune window and set the points per AMU to 25 for
all Tune masses.

2.

If necessary, enable the Low energy setting: 40 eV (200 µAemission).

3.

Delete mass 40 from the Tune Table and insert mass 18 AMU
into the Tune Table.

4.

Turn on the Electron Multiplier so that the mass 18 and 28
peaks are visible in the 5e-11 amp range (or greater). It might
be necessary to increase the dwell time so that the amount ofnoise on the peaks is reduced.

5.

Adjust the peak width and peak position of mass 18 and/or 28
AMU as needed. Set the peak width of these masses to 1.00+/- 0.04 AMU wide at 10% of the peak height. Also set thepeak position to nominal mass.

6.

Save the mass calibration upon exiting Tune mode.

NOTE: Do not attempt to add or delete Tune masses prior to
exiting Tune mode.

MASS SCALE TUNING WITH PROCESS GAS
For mass scale tuning at process pressures, the following
procedure should be used to adjust the Argon (40 AMU) and/or
Nitrogen (28 AMU). This tuning procedure can be used for Argon,
Argon-Nitrogen, or Argon-Oxygen processes.
NOTE: For this mass scale tuning procedure, the Tune Mass
Table should be the default Tune list, which is masses 1,
2, 4, 28, 40, and 86. If this list is not present when the
Tune window is opened, modify the Tune Mass Table asnecessary to show only masses 1, 2, 4, 28, 40, and 86.

CAUTION
Do not attempt to remove masses 1, 2, 4, or
86 AMU from the Tune Table or adjust theresolution at these masses.
Figure 8

1.

Open the Tune window and set the points per AMU to 25 for
all Tune masses.

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Transpector XPR3 Best Known Methods

2.

If necessary, enable the Low energy setting: 40 eV (200 µAemission). Turn off the EM so that the XPR3 is operating in
the FC mode.

3.

Adjust the dwell time as needed to reduce the amount ofnoise on the peaks.

4.

Adjust the peak width and peak position of mass 28 and/or 40
AMU as needed. Set the peak width of these masses to 1.00+/- 0.04 AMU wide at 10% of the peak height. Also set thepeak position to nominal mass.

5.

Save the mass calibration upon exiting Tune mode.

NOTE: Do not attempt to add or delete Tune masses prior to
exiting Tune mode.

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