semi合集-English.pdf - 第279页
SEMI E46-0301 © SEMI 1995 , 2001 4 2 pipettes (glass), 100 m L 1 mi cro dropper with changeabl e tips of 2 µ L (may be PP) 1 mi cro spatula (metal) 1 mi cro balance, measuring rang e 10 -6 g to 1 g at least 10.3.2.1 Prep…
SEMI E46-0301 © SEMI 1995, 20013
ground joint NS80
• aluminum foil
• 2 metal saws
• table vice
• finely toothed metal file
• steel ruler (30 cm)
10.2 Preconditioning Procedure (Thermal
Decontamination) — In order to assure that all
environmental influences are eliminated, all thermal
decontamination procedures described in the following
have to take place immediately before the appropriate
measurements or experiments are performed.
10.2.1 Preconditioning of Aluminum Foil — Two
cross tweezers are flamed with a butane torch in the
fume cupboard (1 min., red heat). A piece of aluminum
foil (20 × 30 cm
2
) is folded multiply and, by using
tweezers, is carefully heated in the flame until fully
converted. After cooling down, the foil is stored on a
fire resistant surface (ceramics preferred).
10.2.2 Preconditioning of Weighing Bottles — The
jaws of the crucible tongs are heated in the butane torch
until they are red hot for two minutes. After a short
cooling period (15 s), the bottom of the weighing bottle
is picked up. For several times, the inner and the outer
surfaces of the glass are heated alternately in the torch
(2 minutes for each run). After approximately 30 s of
cooling down - held in air by the tongs - the flamed
weighing bottle is put down on the preconditioned
aluminum foil. The tongs are allowed to cool for 15 s,
then the lid is prepared in the same way. After 10
minutes of cooling, the lid can be placed on the
weighing bottle.
10.2.3 Preconditioning of Watch Glass — The watch
glass is picked up with preconditioned cross tweezers
and carefully heated in the butane torch for 30 s
(without deformation by melting).
10.2.3.1 Simultaneously, the tips of a second pair of
cross tweezers are heated to red heat. After 30 s, the
watch glass is transferred by these tweezers, carefully
heated for another 30 s to red heat (total heating time, 1
min), and placed on the preconditioned aluminum foil.
After a cooling period of 5 minutes, the watch glass is
picked up with a clean pair of preconditioned cross
tweezers and placed inside the weighing bottle.
10.2.4 Preconditioning of Si-chips — Wafers, as
received, are cut into chips of 20 × 10 mm
2
in size. The
use of cotton gloves is recommended to avoid organic
contamination through fingerprints. Then one Si-chip is
picked up with a pair of cross tweezers and heated to
red hot in a butane torch (30 s). Simultaneously, the tips
of a second pair of cross tweezers are heated to red hot.
After 30 s, the Si-chip is transferred to these tweezers
and heated for another 30 s to red heat (total heating
time, 1 min). After cooling, the Si-chip is transferred
into the preconditioned weighing bottle. The weighing
bottle must be opened and closed only with the
thermally decontaminated crucible tongs.
10.2.4.1 The lid must be placed only on the
preconditioned aluminum foil. Five more Si-chips are
preconditioned as described above and placed into the
weighing bottle. The six Si-chips must not overlap or
touch one another. The Si-chips should be placed on
the preconditioned watch glass.
10.2.5 Preparation of Polymer Material — The table
top vice is mounted on a clean work-bench. The cross
tweezers, the blade of a metal saw, the scalpel, the
metal vernier calliper (within the measuring range), the
steel ruler (in the range of 0 to 3 cm), and the finely
toothed metal file are thermally decontaminated.
Having decontaminated the metal saw, an area of
approximately 50 × 50 mm
2
is sawed off the polymeric
material and fixed with the clean cross tweezers. This
piece of polymer material is then clamped vertically
between the jaws of the vice. An area 12 × 20 mm
2
is
carefully marked with the scalpel and cut out with the
metal saw. Before total separation, the polymer sample
is clamped with cross tweezers while the jaws of the
vice are covered with the decontaminated aluminum
foil. After clamping the polymer sample between the
jaws of the vice, all sides of the polymer sample are
carefully filed to length wit ha metal file (size control
with metal vernier caliper). Then the polymer sample is
placed on a clean watch glass by cleaned tweezers. The
watch glass is positioned on the thermally cleaned
aluminum foil. Both parts are stored inside the
preconditioned weighing bottle which is carefully
closed with its lid. The weighing bottle, within which
the Si-chips are stored, is wrapped in preconditioned
aluminum foil for storage and transportation.
10.3 IMS Measurements Procedure
10.3.1 Blank Measurement — The background signal
level (noise) of the equipment must be defined by
measuring the clean and stabilized IMS-equipment,
without sample, three times for each polarity.
10.3.2 Reference Measurement — All manipulations
etc. with the reference chemicals (Hexaphenylbenzene
and Dioctylphthalate) have to take place entirely in
PFA containers etc. Following equipment is needed:
2 narrow necked flasks (PFA), 250 mL
2 weighing boats (PFA)
! ! low weight, diameter smaller than diameter of
narrow necked flask! !
SEMI E46-0301 © SEMI 1995, 2001 4
2 pipettes (glass), 100 mL
1 micro dropper with changeable tips of 2 µL (may
be PP)
1 micro spatula (metal)
1 micro balance, measuring range 10
-6
g to 1 g at
least
10.3.2.1 Preparation of the reference measurement
with HPB:
10.3.2.1.1 Before the HPB is weighed, the PFA-bottle
and the weighing boat have to be cleaned. For this the
weighing boat and 10 mL benzene are given into the
bottle. The bottle is closed and shaken well for approx.
1 minute. The benzene is discarded. This procedure is
repeated four times. After the last cleaning the empty
open bottle and the weighing boat, placed on a
decontaminated aluminum foil (see Section 10.2.1). are
allowed to dry at room temperature in a fume cupboard
for ten minutes. Then the bottle is closed. The weighing
boat is placed onto the micro balance by thermally
decontaminated cross tweezers. Approx. 5 mg of HPB
are weighed into the weighing boat by use of a
thermally decontaminated micro spatula. The weight is
recorded exactly for the later calculation. The weighing
boat is placed into the PFA bottle by the cross tweezers.
10.3.2.1.2 The volume of the benzene is measured
using a 100 mL-pipette. Before use, the pipette has to
be washed 5 times using 10 mL benzene each time. The
100 mL benzene are filled into the PFA flask, which is
closed immediately.
10.3.2.1.3 First the bottle, now containing HPB and
benzene, is shaken well for three minutes. Often this is
not sufficient for a complete dissolution of the HPB
(visible inspection). To assure complete dissolution, the
PFA flask is placed into an ultrasonic bath for 5
minutes (not longer, because solution may get hot).
Two minutes before the end of that time the preparation
of the silicon chip is started. The piece of silicon is
heated to red heat for one minute, placed on the
thermally decontaminated aluminum foil and given 5
minutes to cool. When the treatment in the ultrasonic
bath is finished, the PFA flask is shaken for three
minutes again, then given 2 minutes for just standing.
10.3.2.1.4 The bottle is opened. By the micro dropper
2 µL are taken from near the surface (tip not more than
1 mm under surface of liquid). The 2 µL are spread
onto the silicon chip in such a way that the liquid on the
chip covers the smallest possible area. Care is to be
taken to prevent large spreading or even dropping off
the liquid (e.g., the Si chip has to be positioned flat).
The liquid is given 5 minutes to evaporate (room
temperature, no extensive blowing of air). Then the
measurement of the HPB reference can be started.
10.3.2.1.5 Before each following HPB measurement
the flask again has to be shaken 3 minutes, 5 minutes
ultrasonic bath, shaking 3 minutes, allow two minutes
of resting. The solution of the HPB in benzene must not
be kept longer than 10 days.
10.3.2.1.6 The reproducibility of the integral value
(see calculation) achieved by this procedure is better
than 4%. Sample measurements shall be performed
only, if the reference measurement has provided a
reproducibility equal to or better than 10%.
NOTE 1: Hexaphenylbenzene has been chosen as a reference
compound because its signal is well-defined and its mobility
value is well separated from the peaks of nearly all other
relevant organic contaminants. It provides positive ions only.
A different reference, Dioctylphthalate, is needed for negative
ions.
10.3.2.1.7 DOP-reference samples: All the same as
HPB, except replacing the benzene by ethanol. The
DOP is weighed using a micro dropper (not spatula).
10.3.2.1.8 The mobility spectrum of dioctylphthalate
is also well separated but there are several peaks due to
thermal decomposition (phthalic anhydride etc.). This
compound is a frequently used plasticizer and therefore
one of the most critical polymer additives.
10.3.3 Measurement of the Headspace Samples —
Positive and negative ions are detected successively in
two separate runs. At least two independent
measurements are carried out for each polarity. Every
measurement to be saved consists of 2000 single scans
and is then repeated. Hence, an automated measurement
is required.
10.3.3.1 The silicon chip is placed in the furnace of
the IMS using thermally decontaminated cross
tweezers. The measurement of the drift time spectrum
(positive or negative polarity) has to be started
immediately after loading the desorption furnace with
the sample (time delay between sample introduction
and starting of the measurement: 15 s).
10.3.4 Termination of the Measurement — The
measurement is terminated when the signal intensity
has decreased to about 10% above the noise of the
blank measurement spectrum. If this point is not
reached after two hours, the measurement should be
terminated; in this case, the investigated sample does
not show suitable material properties.
10.4 Headspace Sampling in Minienvironments —
The crucible tongs are preconditioned as described in
Section 10.2, and the preconditioned aluminum foil is
placed beside the minienvironment that is to be
examined. After opening the minienvironment, the lid
of the weighing bottle is picked up with the crucible
tongs and carefully placed on the aluminum foil. Both
SEMI E46-0301 © SEMI 1995, 20015
the weighing bottle (holding the Si-chips) and its lid are
separately put inside the minienvironment. Then the
minienvironment is closed and kept closed for a defined
period of time. For this test method, one week (168 h)
is defined. After expiry of the storage time, the
weighing bottle is closed with its lid and removed from
the minienvironment.
10.4.1 The same procedure applies to standard wafer
boxes or to SMIF and similar boxes.
10.5 Headspace Sampling of Polymer Material at
Different Temperatures — The prepared polymer
material inside the wrapped weighing bottle (see
Section 10.2.5) is stored:
• either under clean laboratory conditions at room
temperature for a defined period of time
• or in a suitable oven at a temperature of 70°C or
120°C for exactly 1 hour followed by a cooling
period of 1 hour.
10.5.1 The wrapped weighing bottle is handled with a
pair of crucible tongs only.
10.6 Testing Requirements (check for device overload
during measurement)
10.6.1 Positive Ions: Water Cluster Signal Intensity —
The water cluster signal intensity must not decrease by
more than 10% of the blank spectra intensity during
measurement time; otherwise, the ion molecule reactor
has been overloaded. If this is the case, the polymer
sample is not likely to be suitable for use in
semiconductor processing because of unacceptable
properties.
10.6.2 Negative Ions: Oxygen Cluster Signal Intensity
— The same procedure as that in Section 10.6.1 must
be performed for negative ions; in this case, the oxygen
cluster signal intensity must not decrease by more than
20%.
11 Calculation
11.1 Description of Mobility Spectra Evaluation —
The signal intensities of the detected sample
contaminants are integrated over a specific interval for
both polarities. The background signal intensity is
integrated, outside the specific measurement interval,
with preference to spectral region prior to the peaks of
the reactant ions. The total background intensity
(integration of the relevant background signal) is
subtracted from the integrated contamination intensity
(background correction). The mean value of the
contamination signal from the blank measurement
(Section 10.3.1) spectra is subtracted accordingly. This
leads to individual contamination values from each
sample spectrum.
11.2 Calculation of reduced mobility:
K=E
-1
1
d
/t
d
and
K
0
= K (p/p
0
) (T
0
/T)
K : ion mobility (cm
2
/Vs)
K
0
: reduced ion mobility (cm
2
/Vs)
p: pressure
p
0
: standard pressure
T : temperature
T
0
: standard temperature (273.15K)
l
d
: drift length (cm)
t
d
: drift time (s)
E : electric field strength (V/cm)
K : Kelvin
11.2.1
Table 1 shows the specified integration range;
all reduced mobility values are given in units of cm
2
/Vs.
11.2.2 The resulting integrals for each spectrum are
summed up for the whole desorption time. This value is
compared to the appropriate value of the reference
sample (HPB or DOP).
11.2.3
This procedure ensures the comparison of the
evaluated sample contamination values between
different laboratories and measurement equipments.
12 Related Documents
12.1 K. Budde, “Application of Ion Mobility
Spectrometry to Semiconductor Technology,”
Proceedings of the Satellite Symposium to ESSDERC
89 (Berlin) of the Electrochemical Society (the
Electrochemical Society Pennington, 1990) PV 90-11,
p.215.
12.2
K. Budde, W. J. Holzapfel, “Measurement of
Organic Contamination from Silicon Surfaces,”
Proceedings, 38th Meeting, Institute of Environmental
Sciences, 3.-8.5.1992, Nashville, TN, p.483.
12.3
K. Budde, W. J. Holzapfel, “Detection of Volatile
Organic Surface Contaminations Arising from Wafer
Boxes and Cleaning Processes,” Proceedings of the
First International Symposium on Semiconductor
Wafer Bonding, (the Electrochemical Society
Pennington, 1992) PV 92-7, p. 271.
12.4
Proposal: SEMATECH Test Method for
Determining Outgassing Products from Semiconductor
Product Carriers.
12.5
S.N. Ketkar, S.M. Penn, and W.L. Fite,
“Influence of Coexisting Analytes in Atmospheric
Pressure Ionization Mass Spectrometry,” Anal. Chem.
63, (1991) 924.