Data analysis sheet for determining the
Young's modulus value of a thin film layer with the analysis
incorporating a frequency calibration
a) b)
Figure YM.2.1. For CMOS cantilever a) a design
rendition and b) a cross section
To obtain
the following measurements,
consult SEMI standard test
method MS4 entitled "Test
Method for Young's Modulus
Measurements of Thin, Reflecting
Films Based on the Frequency
of Beams in Resonance."
IDENTIFYING INFORMATION:
date data taken (optional)
=
/
/
Table 1 -
Preliminary
INPUTS
Description
1
=
×
magnification
2
mat=
composition of the thin film layer
3*
ρ=
g/cm3
density of the thin film layer
4
σρ=
g/cm3
one sigma uncertainty of the value of
ρ
5*
μ=
×10-5
Ns/m2
viscosity of the ambient surrounding the cantilever
6
σμ=
×10-5
Ns/m2
one sigma uncertainty of the value of
μ
7
temp=
temperature during measurement
(should be held constant)
8*
W=
μm
suspended beam width
9
σW=
μm
one sigma uncertainty of the value of W
10*
t=
μm
thickness of the thin film layer
11
σthick=
μm
one sigma uncertainty of the value of t
12
dgap=
μm
gap depth (distance between the
bottom of the suspended beam and the underlying layer)
13*
Einit=
GPa
initial estimate for the Young's
modulus value of the thin film layer
14
finstrument=
Hz
for calibrating the time base of the instrument:
the frequency setting for the calibration measurements
(or the manufacturer's specification for the clock
frequency)
15
fmeter=
Hz
for calibrating the time base of the instrument:
the calibrated average frequency of the calibration
measurements (or the calibrated average clock frequency)
taken with a frequency meter
16
ucmeter=
Hz
for calibrating the time base of the instrument:
the uncertainty of the frequency measurements taken with
the frequency meter
* The five starred entries in this
table are required inputs for the calculations in the
Preliminary Estimates Table.
Table 2 - Cantilever
INPUTS
Description
17
name=
cantilever name (optional)
18
=
orientation of the cantilever
19*
Lcan=
μm
suspended cantilever length
20
which cantilever on the test chip,
where "first" corresponds to the topmost cantilever in
the column or array that has the specified length?
21
σL=
μm
one sigma uncertainty of the value of Lcan
22
fresol=
Hz
uncalibrated
frequency resolution for the given set of measurement
conditions
23
fmeas1=
kHz
first uncalibrated, damped resonance frequency
measurement
(or first uncalibrated, undamped resonance frequency measurement, for
example, if the measurements were performed in a vacuum)
24
fmeas2=
kHz
second uncalibrated, damped resonance frequency
measurement
(or second uncalibrated, undamped resonance frequency measurement, for
example, if the measurements were performed in a vacuum)
25
fmeas3=
kHz
third uncalibrated, damped resonance frequency
measurement
(or third uncalibrated, undamped resonance frequency measurement, for
example, if the measurements were performed in a vacuum)
* The starred entry in this table
is a required input for the calculations in the Preliminary
Estimates Table.
Table 3 - Fixed-Fixed Beam
INPUTS
(if cantilever not available)
Description
26
name2=
fixed-fixed beam name (optional)
27
=
orientation of the fixed-fixed
beam
28*
Lffb=
μm
suspended fixed-fixed beam length
29
which fixed-fixed beam on the test
chip, where "first" corresponds to the topmost
fixed-fixed beam in the column or array that has the
specified length?
30
fffb=
kHz
average uncalibrated resonance frequency of the
fixed-fixed beam
* The starred entry in this table
is a required input for the calculations in the Preliminary
Estimates Table.
Table 4 -
Optional
INPUTS
For residual stress
calculations:
Description
31
εr=
×10-6
residual strain
of the thin film layer
(Compressive residual strain can
be found using ASTM E 2245 and Data Sheet RS.1 or RS.2.)
32
ucεr=
×10-6
combined standard uncertainty
value for residual strain
(For compressive residual strain,
ucεr
can be found using Data Sheet RS.1 or RS.2.)
For stress gradient
calculations:
33
sg=
m-1
strain gradient of the thin film layer
(can be found using ASTM E 2246
and Data Sheet SG.1 or SG.2)
34
ucsg=
m-1
combined standard uncertainty value
for strain gradient
(can be found using Data Sheet SG.1
or SG.2)
Table 5 - Preliminary
ESTIMATES*
Description
35
fcaninit=
kHz
= SQRT[Einit t2
/ (38.330
ρ Lcan4)]
(estimated
resonance frequency of the cantilever)
36
fffbinithi=
kHz
= SQRT[Einit
t2 / (0.946 ρ
Lffb4)]
(estimated
upper bound for the resonance frequency of the fixed-fixed
beam)
37
fffbinitlo=
kHz
= SQRT[Einit
t2
/ (4.864 ρ Lffb4)]
(estimated
lower bound for the resonance frequency of the fixed-fixed
beam)
38
Q=
= Wt2
SQRT(ρ
Einit)
/ (24
μ
Lcan2)
(estimated
Q-factor)
39
pdiff=
%
={1-SQRT[1-1
/ (4 Q2)]}×100
% should be < 2 %
(estimated
percent difference between the damped and undamped resonance
frequency of the cantilever)
* The seven starred inputs in the first three tables are required
for the calculations in this table.
OUTPUTS:
Table 6 -
Frequency calculations:
Description
40
calf =
= fmeter /
finstrument (the calibration factor
for a frequency measurement)
41
fmeasave=
kHz
= AVE [fmeas1, fmeas2,
fmeas3]calf
(average calibrated damped resonance frequency of
the cantilever, fdampedave, or
average calibrated undamped resonance frequency of the cantilever if,
for example, the measurements were performed in a vacuum)
42
fundamped1=
kHz
= fdamped1/ SQRT[1-1/(4Q2)]
where fdamped1=fmeas1(calf)
(first calibrated undamped resonance frequency
calculated from the cantilever's first damped resonance
frequency measurement, if applicable)
43
fundamped2=
kHz
=fdamped2 / SQRT[1-1/(4Q2)] where fdamped2=fmeas2(calf)
(second calibrated undamped resonance frequency
calculated from the cantilever's second damped resonance
frequency measurement, if applicable)
44
fundamped3=
kHz
= fdamped3/ SQRT[1-1/(4Q2)] where fdamped3=fmeas3(calf)
(third calibrated undamped resonance frequency
calculated from the cantilever's third damped resonance
frequency measurement, if applicable)
45
fcan=
kHz
= AVE [fundamped1, fundamped2,
fundamped3]
(average calibrated undamped resonance frequency
of the cantilever assuming fmeas1, fmeas2, and fmeas3 from
the second table are damped resonance frequencies)
46
σfreq=
= STDEV (fundamped1, fundamped2, fundamped3)
(one sigma
uncertainty of the value of fcan
assuming fmeas1, fmeas2,
and fmeas3 from the second table
are damped resonance frequencies)
1.
Young's modulus calculation
(as obtained from the cantilever assuming clamped-free
boundary conditions):
a.
E =
38.330 ρ fcan2 Lcan4
/ t2 =
GPa
(Use this value if fmeas1,
fmeas2, and fmeas3
in the second table are damped
resonance frequencies.)
b.
E =
38.330 ρ fmeasave2
Lcan4
/ t2 =
GPa
(Use this value if fmeas1,
fmeas2, and fmeas3
in the second table are undamped
resonance frequencies.)
c. ucE =
SQRT(uthick2
+ uρ2
+ uL2 + ufreq2
+ ufresol2
+ udamp2
+ ufreqcal2
) =
uthick
=
GPa
Type B
uρ
=
GPa
Type B
uL
=
GPa
Type B
ufreq
=
GPa*
Type A ufresol
=
GPa
Type B
udamp
=
GPa*
Type B ufreqcal
= GPa Type B *assumes fmeas1, fmeas2,
and fmeas3 in the second table are damped
resonance frequencies
d. Report the results as follows: Since it can be assumed that the estimated values
of the uncertainty components are approximately uniformly or Gaussianly distributed with approximate
combined standard uncertainty
ucE, the Young's modulus value is believed to lie in
the interval E ±
ucE (expansion factor
k=1) representing a level of
confidence of approximately 68 %.
2. Young's
modulus calculation
(as obtained from a fixed-fixed beam...not
recommended):
a. Esimple = 4.864
ρ ( fffb calf )2 Lffb4
/
t2= GPa (as obtained from
the fixed-fixed beam assuming simply-
supported boundary conditions for both
supports) b. Eclamped = 0.946
ρ (
fffb calf)2
Lffb4 /
t2=
GPa (as obtained from
the fixed-fixed beam assuming
clamped-clamped boundary conditions)
c. E = (Esimple
+ Eclamped) / 2 =
(use this value, if must)
d. uE
= (Esimple - Eclamped)
/ 6 =
(as obtained from a Type B analysis)
e. Report the results as follows: Since it can be assumed that the
estimated value of the standard
uncertainty, uE, is approximately
Gaussianly distributed, the Young's modulus value is believed to lie in
the interval E ±
uE (expansion factor k=1)
representing a level of confidence of approximately 68 %.
Table 7 -
Optional
OUTPUTS
(using E and ucE
from the cantilever and assuming fmeas1,
fmeas2,
and fmeas3
in the second table are damped resonance frequencies)
For residual stress:
Description
47
σr=
MPa
= E εr
(residual
stress of the thin film layer)
48
ucσr=
MPa
= SQRT[uE(σr)2+
uεr(σr)2]
(combined
standard uncertainty value for residual stress where each of
the standard uncertainty components is obtained using a
Type B analysis)
49
uE(σr)=
MPa
= [ (E+3ucE)|εr|
- (E-3ucE)|εr|
] / 6 = ucE|εr|
(component in the combined standard
uncertainty calculation for residual stress that is due to
the measurement uncertainty of E)
50
uεr(σr)=
MPa
= [ E(|εr|+3ucεr)
- E(|εr|-3ucεr)
] / 6 = ucεrE
(component in the combined standard
uncertainty calculation for residual stress that is due to
the measurement uncertainty of
εr)
For stress gradient:
51
σg=
GPa/m
= E sg
(stress
gradient of the thin film layer)
52
ucσg=
GPa/m
= SQRT[uE(σg)2
+ usg(σg)2]
(combined
standard uncertainty value for stress gradient where each of
the standard uncertainty components is obtained using a
Type B analysis)
53
uE(σg)=
GPa/m
= [ (E+3ucE)sg
- (E-3ucE)sg
] / 6 = ucE sg
(component in the combined standard
uncertainty calculation for stress gradient that is due to
the measurement uncertainty of E)
54
usg(σg)=
GPa/m
= [ E(sg+3ucsg)
- E(sg-3ucsg)
] / 6 = ucsgE
(component in the combined standard
uncertainty calculation for stress gradient that is due to
the measurement uncertainty of sg)
Modify the input data, given the information supplied in any flagged
statement below, if applicable, then recalculate:
1.
Please provide inputs to Tables 1 and 2 for calculations
using data from a cantilever.
2.
Please provide
inputs to Table 3, ρ,
W, t, and Einit for
calculations using data from a fixed-fixed beam, if
applicable.
3.
The value for mag should be greater than or equal to
20×.
4.
The value for
ρ
should be between 1.00 g/cm3 and 5.00 g/cm3.
5.
The value for
σρ
should be between 0.0 g/cm3 and 0.10 g/cm3.
6.
The value for
μ should be between
0.70×10-5
Ns/m2
and 3.0×10-5
Ns/m2.
7.
The value for
σμ
should be between 0.0
Ns/m2 and
0.05×10-5
Ns/m2.
8.
The value for temp
should be between 15 °C
and 30 °C.
9.
The value for W should be greater than t and
less than Lcan.
10.
The value for W should be greater than t and
less than Lffb, if inputted.
11.
The value for
σW
should be between 0.0 μm
and 2.0
μm.
12.
The value for t
should be between 0.000
μm and 10.000 μm.
13.
The value for
σthick
should be between 0.0
μm and 0.3
μm.
14.
Squeeze film damping expected for the
cantilever since dgap < W
/ 3.
15.
The value for Einit
should be between 10 GPa
and 300 GPa.
16.
The
value for ucmeter should be between
0.0 Hz and 25.0 Hz.
17.
The value for Lcan
should be between 0
μm and 1000
μm.
18.
The value for
σL
should be between 0.0
μm
and 2.0
μm.
19.
The value for fresol
should be between 0 Hz
and 50 Hz.
20.
The values for fmeas1,
fmeas2,and
fmeas3should be between 5.00 kHz and 300.0
kHz.
21.
If inputted, the value for
Lffb should be between 0
μm and 1000
μm.
22.
If inputted, the value for fffb
should be between 5.0 kHz and 1200 kHz.
23.
If inputted, the value for
εrshould be between -100×10-6
and 100×10-6
and not equal to 0.0.
24.
If inputted, the value for ucεrshould be between 0.0 and 4.0×10-6.
25.
If inputted, the value for sg
should be between 0.0 m-1
and 20.0 m-1.
26.
If inputted, the value for ucsg
should be between 0.0 m-1
and 2.0 m-1.
27.
The values for fmeas1,
fmeas2, and fmeas3
are not within 20 kHz of fcaninit.
28.
If inputted, the value for fffb
should be between fffbinitlo and
fffbinithi.
29.
The value for pdiff
should be between 0 %
and 2 %.
30.
The value for calf should be
between 0.9990 and 1.0010.
31.
The value for
σfreq
should be between 0.0 kHz and 0.5 kHz, inclusive.
32.
The value of E obtained from the
cantilever should be within 20 GPa of Einit.
33.
The values for uthick,
uρ,
uL,
ufreq, ufresol, udamp,
and ufreqcal
should be between 0 GPa and 5 GPa, inclusive.
34.
The value of ucEobtained from the cantilever should be
between 0 GPa and 10 GPa.
35.
If applicable, the value of E
obtained from the fixed-fixed beam should be within 30 GPa
of Einit.
36.
If applicable, the value of
uE
obtained from the fixed-fixed beam should be between 0 GPa
and 20 GPa.