semi合集-English.pdf - 第7245页
SEMI MF525-0705 © SEMI 2003, 2005 8 13 Procedure 13.1 Handle t h e specim en carefully to avoid c ontamination or damage to the surface. 13.2 Make all m easurements with an ambient tem peratur e of 23 ± 3°C. Record the a…
SEMI MF525-0705 © SEMI 2003, 2005 7
11.4.1 Measure the spreading resistance of the uniform p-type silicon specimen (see ¶8.2) in accordance with
¶¶13.4 through 14.2. Consider the probes to be satisfactory if the measured spreading resistance is within ±10% of
the usual value that has been found to be consistent over a long period of time.
11.4.2 If the probes are not satisfactory, repeat the conditioning step or use new probe tips.
11.5 Using the microscope at 400×, examine the probe marks for reproducibility (Note 7). If the probe marks from
a given probe do not appear similar, recondition (see ¶11.4) or replace the probe.
NOTE 7: All the marks from a specific probe should appear to be similar. Probe imprints from different probes need not be
identical.
11.6 If the two-probe arrangement is being employed, verify that the spreading resistances of the two probes are
equal to within 10% when measured on the uniform p-type specimen (see ¶8.2) using the one-probe configuration.
If they are not, recheck or adjust the loading (see ¶11.2) and descent rate (see ¶11.3) to be equal on both probes. If
satisfactory results are not achieved with equal probe loading and descent rate, recondition (see ¶11.4) or replace the
probes.
11.7 Connect the appropriate electrical circuit (see Figures 1 through 3). If a voltage source is used (constant-
voltage or log comparator methods), adjust the potential to 20 mV or less. If a current source is used (constant-
current method), short circuit the output.
11.8 Note and record the voltage to be applied in millivolts as V (constant-voltage method), the current to be
applied in milliamperes as I (constant-current method), or the value of the standard resistor in ohms as R
0
(log
comparator method).
12 Calibration
12.1 Measure the resistivity of the specimens to be used as standards (see ¶8.1) at 23 ± 3°C in accordance with
SEMI MF84, if not previously measured. Record the results or the previously determined value.
12.2 Prepare the surface of the calibration specimens using the materials of ¶¶8.4.1, 8.4.2, 8.4.3, or 8.4.4 using
manual or machine procedures, the choice of materials and procedure being governed only by the requirement that
the calibration specimens must be prepared in the same manner as the specimens to be tested. If the specimen to be
tested is epitaxial, the use of a lapped surface is not to be used for the calibration specimens.
12.2.1 Clean the polishing material from the calibration specimens using water, or solvent in the case of solvent-
soluble vehicles used for certain diamond polishes. Place the specimen on a hot plate at 150 ± 20°C for 10 to 15
min if calibration specimens were prepared with silica or aluminum oxide polishing or lapping compounds.
NOTE 8: If the chosen calibration specimen preparation is anything other than lapping with 5 m aluminum oxide, it is
advisable to remove a minimum of 25 m of specimen surface the first time the specimens are prepared, subsequent to resistivity
measurement by SEMI MF84 in order to remove any subsurface damage left by the 5 m lapping process required in SEMI
MF84.
NOTE 9: The frequency with which calibration specimen surfaces should be re-prepared is a function both of the inherent
stability of the surface for the chosen preparation procedure, and of possible exposure of the calibration specimens to
environments such as acid fumes. The stability of the specimen surfaces for the chosen procedure should be established by each
user of this method.
12.3 Make a minimum of 20 spreading resistance measurements on each of the proposed standards. Make the
measurements as closely as possible to the region where the four-probe measurements (see ¶12.1) were made. Make
these measurements over a length approximately equal to the separation of the outer probe tips of the four-probe
array used for the resistivity measurements. Record the results.
12.4 Compute the mean of the measurements made on each of the proposed standards and calculate the standard
deviation for each set of measurements. If the standard deviation of the spreading resistance measurements is
greater than 10% of the mean, do not use the specimen as a calibration standard.
12.5 Using the resistivity value and the corresponding spreading resistance mean for each suitable calibration
standard, fit an appropriate polynomial, piecewise linear, or spline curve to the calibration data for the groups of
specimens of each conductivity type and orientation. Plot the data and calibration curve on graph paper.
SEMI MF525-0705 © SEMI 2003, 2005 8
13 Procedure
13.1 Handle the specimen carefully to avoid contamination or damage to the surface.
13.2 Make all measurements with an ambient temperature of 23 ± 3°C. Record the ambient temperature.
13.3 Determine the orientation of the specimen surface in accordance with SEMI MF26, determine the
conductivity type of the substrate and, if present, the epitaxial layer in accordance with SEMI MF42. For epitaxial
layers, determine the thickness in accordance with either SEMI MF95 or SEMI MF110. Record the results.
13.4 Prepare all bulk specimens to be tested using the same procedure as was used for the calibration specimens in
¶12.2. Do not prepare the surface of any epitaxial specimens. Thoroughly clean polishing material residues from
the specimen using water or solvent as necessary. If the materials of ¶8.4.1 or ¶8.4.3 were used for specimen
preparation, proceed to ¶13.5, otherwise proceed to ¶13.6.
13.5 Place the specimen on a hot plate with the surface to be measured upwards, not in contact with the hot plate.
Heat the specimen in air at 140 ± 20°C for 10 to 15 min. Remove the specimen from the hot plate. Allow the
specimen to return to 23 ± 3°C before continuing with the measurements.
13.6 Rigidly mount specimen on stage under probes. Use of wax mounting to base block used to hold specimen
during surface preparation or use of vacuum clamping is acceptable. Position the specimen on the specimen holder
so that the probe or probes will be applied at the desired measurement location.
13.7 Lower the points to make contact with the specimen surface, and adjust to within 0.1% (unless the comparator
method is being used) the voltage or current source to the desired value (see ¶11.8).
13.8 After a stabilization period of 1 s or longer, measure and record the current in milliamperes as I (constant-
voltage method), the voltage in millivolts as V (constant-current method), or the output of the log comparator as
log(i
1
/i
2
) (log comparator method).
13.9 Adjust the voltage source to a value of 20 mV or less or short circuit the current source and lift the probes.
13.10 Move the specimen to the next position, making sure that the step spacing is larger than the diameter of the
specimen area damaged by the probes.
13.11 Note and record the step spacing.
13.12 Repeat ¶¶13.6 through 13.11 until the desired number of measurements has been made.
14 Calculations
14.1 Calculate the spreading resistance, R
s
, in ohms, for each measurement as follows:
14.1.1 Constant-Voltage Method
I
V
R
s
(3)
where:
V
= applied voltage, mV, and
I = measured current, mA.
14.1.2 Constant-Current Method
I
V
R
s
(4)
where:
V
= measured voltage, mV, and
I = applied current, mA.
14.1.3 Comparator Method
)/log(
210
iiRR
s
(5)
SEMI MF525-0705 © SEMI 2003, 2005 9
where:
R
0
=
resistance of the standard resistor, , and
log(i
1
/i
2
) = output of the log comparator.
14.2 Calculate and record the mean value of the spreading resistance of each specimen.
14.3 Using the appropriate calibration curve (see ¶12.4), determine the resistivity that corresponds to the mean
value of spreading resistance. Record this as the average resistivity of the region measured.
15 Report
15.1 Report the following information:
15.1.1 Date of test,
15.1.2 Location of test,
15.1.3 Identification of operator,
15.1.4 Identification of measuring instrument(s),
15.1.5 Specimen identification,
15.1.6 Loading on the probe tips,
15.1.7 Crystallographic orientation of the specimen,
15.1.8 Conductivity type of epitaxial layer, if present, and substrate,
15.1.9 Thickness of epitaxial layer, if present, and method of measurement,
15.1.10 Average resistivity of the region measured,
15.1.11 Step spacing,
15.1.12 Probe separation,
15.1.13 Ambient temperature, and
15.1.14 Surface preparation.
16 Precision and Bias
16.1 The precision of this test method is based on an analysis of two components of random error evaluated from a
multilaboratory experiment that used small rectangular chips from 14 bulk silicon specimens and for which 21 sets
of data were reported by 12 different laboratories. The specimens tested were four (111) p-type chips from about
0.05 to about 1500 ·cm, six (111) n-type chips from about 0.01 to about 500 ·cm, one (100) n-type chip at about
10 ·cm and three (100) p-type chips from about 0.01 to about 10 ·cm. Analyses of data to obtain estimates of
random error were done separately for three categories of specimen preparation for which sufficient data were
returned to obtain reliable estimates. In each category of specimen preparation, estimates of random error were
obtained for the resistivity range from 0.01 to 200 ·cm; estimates were not obtained from the two specimens of
highest resistivity.
16.2 The two components of within-laboratory random error that were evaluated for each specimen preparation
category and resistivity range are the repeatability,
r
, the relative standard deviation of a set of measurements
obtained after a single preparation of a specimen, and the reproducibility,
R
, the relative standard deviation of
measurement averages following re-preparations of a specimen. A summary of the estimates of these components
based on the results of the multilaboratory experiment is given in Table 1, which gives the 90th percentile values for
r
and
R
in each category. The 90th percentile value is the value of
r
or
R
below which 90% of the contributed
values for that parameter in that category fall. It is expected to be a conservative estimate of
r
or
R
about 90% of
the time for predicting the precision achievable by a well-controlled laboratory. The use of percentile distributions
of the test data to obtain these estimates of
r
and
R
for the entire resistivity range results in a high value for the