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SEMI M58-0704 © SEMI 2004 4 10.8.1 Determine the F WHM values in nm obt ained from the histograms and record these in the FWHM on Wafer colum ns of the SSIS Data portions of the data sheet. 10.8.2 If desired, enter the p…
SEMI M58-0704 © SEMI 2004 3
5%. It is used in the measurement of (1) peak diameter
repeatability and (2) peak diameter bias of the
deposition system.
2
8.1.1.2 Bottle B contains a suspension of PSL spheres
with a single well defined peak diameter that is at least
20% smaller than that of the spheres in Bottle A, and a
FWHM that is significantly larger than 5%. It is used
in the measurement of (1) peak diameter repeatability
and (2) FWHM of the deposition system when filtering
a smaller diameter with a broad diameter distribution.
8.1.1.3 Bottle C contains a suspension of PSL spheres
with a single well defined peak diameter that is at least
30% larger than Bottle A, and a FWHM that, if
possible, is larger than 5%. It is used in the
measurement of (1) peak diameter repeatability and (2)
FWHM of the deposition system when filtering a larger
diameter with a broad diameter distribution.
NOTE 1: Because spheres with peak diameters larger than
100 nm often have a FWHM smaller than 5% it may not be
possible to secure a bottle with FWHM greater than 5%; in
this case use a bottle with as large a FWHM as possible.
8.2 Wafers
8.2.1 One or more polished silicon wafers of
appropriate diameter that have a high enough surface
quality that the smallest PSL spheres deposited can be
detected on the SSIS with a capture rate greater than
95% as determined in accordance with SEMI M53.
9 Preparation and Control of Apparatus
9.1 The deposition system under test must be available
to run without scheduled, or unscheduled, maintenance
or other interruption for the full five day test period.
9.2 Maintain a control chart of the voltage(s) associated
with one or more peak diameters on a daily or weekly
basis to ensure that the deposition system is under
control.
9.3 Repeat the entire test procedure, calculations, and
interpretation of results (see Sections 10 through 12) on
an annual basis or whenever the control chart shows out
of control conditions.
10 Procedure
10.1 Obtain three bottles of suspensions of PSL spheres
(A, B and C) as described in Section 8.1. Record the
peak diameter certified 1σ relative uncertainty, and
%FWHM of the particle distribution in Bottle A on the
data sheet. Record the supplier, part number, and lot
number for each bottle of suspensions. If available,
record the same information for Bottles B and C. An
2 At the present time, NIST SRM 1963 meets these requirements.
example data sheet is shown in Figure 1 and a
completed example is shown in Figure R2-1.
NOTE 2: If desired, the data sheet can be set up as a spread-
sheet that automatically completes the calculations discussed
in Section 11. This spreadsheet is outlined in Related
Information 2. If this is done, error messages will appear in
the cells that contain the equations to perform the calculations
until the data has been entered.
10.2 Record on the data sheet the laboratory name, the
contact for the test, the address, telephone number, and
e-mail address by which the contact can be reached, and
the dates of the test.
10.3 Record on the data sheet the identification of the
deposition system under test, including supplier and
model number, serial number, and software revision. If
the test has been performed previously on this
deposition system, enter the date of the last previous
test.
10.4 Choose one or more wafers upon which to make
the depositions and load the first wafer into the
deposition system.
10.5 Choose a value of N (between 1000 and 3000)
particles for the deposition count and record this value
on the data sheet. Use the same value of N for all
depositions.
10.6 Depositions on the First Day
10.6.1 On the morning of the first day of a five day
period, scan the particles from Bottle A in the
deposition system to find the peak diameter. Record
the peak diameter as found by the deposition system in
the Day 1 row of the first Bottle A column of the
Deposition System Diameter portion of the data sheet.
Then use the deposition system, centered at the peak
diameter, to make a deposition of N particles at a
location on the first wafer.
10.6.2 Repeat this procedure for bottles B and C,
recording the peak diameter as found by the deposition
system in the appropriate Day 1 columns of the
Deposition System Diameter portion of the data sheet.
10.6.3 Near the end of the day, make a final peak
diameter scan (but not an additional deposition) of
bottle A. Record the peak diameter as found by the
deposition system in the Day 1 row of the second Bottle
A column of the Deposition System Diameter portion
of the data sheet.
10.7 Repeat the procedures of subsection 10.6 for the
next four days, using additional locations on the wafer
or on additional wafers.
10.8 At the end of the five days run the wafer (or
wafers) on an SSIS, to obtain a histogram for each of
the 15 depositions.
SEMI M58-0704 © SEMI 2004 4
10.8.1 Determine the FWHM values in nm obtained
from the histograms and record these in the FWHM on
Wafer columns of the SSIS Data portions of the data
sheet.
10.8.2 If desired, enter the peak diameter values and
counts found from the SSIS histograms in the Measured
Peak and Count columns of the SSIS Data portions of
the data sheet. These values may be used to evaluate
SSIS calibration and deposition system count accuracy,
respectively, but they are not used to evaluate the
deposition system against the requirements of SEMI
M52.
11 Calculations (see Note 2)
11.1 Calculate and record the mean diameter in nm to
one decimal place and the relative standard deviation as
a percentage of the mean of each of the four columns of
the Deposition System Diameter portion of the data
sheet.
11.2 Calculate and record the Relative FWHM in each
appropriate column of the SSIS Data portions of the
data sheet by dividing the FWHM in nm by the
measured peak diameter in nm and converting to
percent with two decimal places.
11.3 Calculate the mean and standard deviation of each
of the columns in the three SSIS Data portions of the
data sheet.
11.4 Calculate the expanded relative combined standard
uncertainty, U
relA
, for the peak diameter associated with
the deposition from Bottle A as follows:
22
2
BottleADepArelA
usU += (1)
where:
s
DepA
=
p
ooled relative standard deviation fo
r
system repeatability associated with the
deposition from Bottle A taken from the
Deposition System Diameter Data portion o
f
the data sheet by adding the square of the
standard deviation from the five depositions
made at the beginning of each day to the
square of the standard deviation from the
five scans made at the end of each day,
dividing by 2, and taking the square root.
u
BottleA
=
1σ relative combined standard uncertainty
of the peak diameter of the particle
distribution in Bottle A as certified by the
manufacturer found in the Bottle Pea
k
Diameter portion of the data sheet.
Record the result as a percentage to one decimal place
in the Bottle A column of the Dep Peak Uncertainty
row of the Analysis portion of the data sheet. Take the
certified value of the peak diameter of the deposition as
the peak diameter of the deposition from Bottle A.
11.5 Calculate the expanded relative combined standard
uncertainty, U
relB
, for the peak diameter associated with
the deposition from Bottle B as follows:
22
2
BottleADepBrelB
usU += (2)
where:
s
DepB
= relative standard deviation of the measured
p
eak from Bottle B taken from the
Deposition System Diameter Data: Bottle B
portion of the data sheet, and
u
BottleA
has the same meaning as in Equation (1). The
first term of this equation accounts for the variation due
to the uncertainty in the finding of the peak diameter of
Bottle B by the DMA and the second term accounts for
the uncertainty in the certified peak diameter of the
suspension in Bottle A, which is used to correct the
peak diameter of Bottle B as found by the DMA.
Record the result as a percentage to one decimal place
in the Bottle B column of the Dep Peak Uncertainty
row of the Analysis portion of the data sheet.
Determine the peak diameter of the deposition from
Bottle B as follows:
−
+=
A
AA
BB
Cert
MeanCert
MeanPeakDia 1 (3)
where:
Mean
B
= value of the mean deposition diameter fro
m
Bottle B taken from the Deposition System
Diameter Data portion of the data sheet, and
Mean
A
= average mean deposition diameter fro
m
Bottle A taken from the De
p
osition Syste
m
Diameter Data portion of the data sheet by
adding the mean from the depositions at the
b
eginning of the day to the mean from the
scans at the end of the day, and
Cert
A
= value of the peak diameter in the suspension
in Bottle A as certified by the manufacture
r
found in the Bottle Peak Diameter portion o
f
the data sheet.
Record PeakDia
B
in the Bottle B column of the
Peak(DepSysCorrected) row of the Analysis portion of
the data sheet.
11.6 Calculate the expanded relative combined standard
uncertainty, U
relC
, for the peak diameter associated with
the deposition from Bottle C as follows:
22
2
BottleADepCrelC
usU += (4)
SEMI M58-0704 © SEMI 2004 5
where:
s
DepC
= relative standard deviation of the measured
p
eak from Bottle C taken from the
Deposition System Diameter Data: Bottle C
portion of the data sheet, and
u
BottleA
has the same meaning as in Equation (1). Again,
the first term of this equation accounts for the variation
due to the uncertainty in the finding of the peak
diameter of Bottle C by the DMA and the second term
accounts for the uncertainty in the certified peak
diameter of the suspension in Bottle A, which is used to
correct the peak diameter of Bottle C as found by the
DMA. Record the result as a percentage to one decimal
place in the Bottle C column of the Dep Peak
Uncertainty row of the Analysis portion of the data
sheet. Take the peak height of the deposition as the
chosen value of deposition diameter corrected as
follows:
−
+=
A
AA
CC
Cert
MeanCert
MeanPeakDia 1
(5)
where:
Mean
C
= value of the mean chosen deposition
diameter from Bottle C taken from the
Deposition System Diameter Data portion o
f
the data sheet, and
Mean
A
and Cert
A
have the same meaning as in Equation
(3). Record PeakDia
C
in the Bottle C column of the
Peak(DepSysCorrected) row of the Analysis portion of
the data sheet.
11.7 Record the Mean Relative FWHM values for each
of the three bottles in the SSIS Data sections as
percentages with one decimal place in the FWHM SSIS
row of the Analysis portion of the data sheet.
11.8 Average the two mean deposition system
diameters for Bottle A found in the Deposition System
Diameter data and record this average and the mean
deposition system diameters for Bottles B and C in the
Peak (Dep System) row of the Analysis portion of the
data sheet. This is additional information only.
11.9 Record the Mean Measured Peak from the three
SSIS Data sections for each of the three Bottles in the
Peak (SSIS) row of the Analysis portion of the data
sheet. This is additional information only.
11.10 Record the value of N (Particles Deposited) in the
Count row of the Analysis portion of the data sheet.
12 Interpretation of Results
12.1 If a value for Bottle A, B, or C in the Dep Peak
Uncertainty row of the Analysis portion of the data
sheet is greater than 3.0%, the deposition system cannot
be used with this bottle or these settings to produce
calibration standards that meet the uncertainty
requirements of SEMI M52.
12.2 If a value for Bottle A, B, or C in the FWHM row
of the Analysis portion of the data sheet is greater than
5.0%, the deposition system cannot be used with this
bottle or these settings to produce calibration standards
that meet the FWHM requirements of SEMI M52.
12.3 Although it is not required by SEMI M52, the
mean for the deposited diameters determined by the
SSIS can be compared to the values found by the
deposition system and the PSL sphere manufacturer. A
significant difference in mean may imply that the SSIS
is not properly calibrated.
12.4 Although it is not required by SEMI M52, the
mean count values determined by the SSIS may be
compared to the count value set by the deposition
system. A significant difference may imply that the
deposition system needs to be adjusted.
13 Report
13.1 Report all the information, data, and calculations
recorded on the data sheet. A completed example of
such a report is provided in Related Information 2.
14 Precision and Bias
14.1 No data regarding precision and bias are presently
available. At present there are no plans to develop such
data, but should such data become available, it will be
added to this test method.