4 determining z-ratio, Section 6.4, determining z-ratio, on – INFICON IQM-233 Thin Film Deposition Controller PCI-Express Card Operating Manual User Manual
Page 89
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PN
07
4-
58
4-
P1
A
IQM-233 Operating Manual
5
Enter this new value for Tooling, rounded to the nearest 0.01%, in the Tooling
box of the IQM-233 Standard software;
T
m
will equal
T
x
if calculations are done
properly.
NOTE: Due to variations in source distribution and other system factors, it is
recommended that a minimum of three separate evaporations be made to
obtain an average value for Tooling.
6.4 Determining Z-Ratio
A list of Z-Ratio values for materials commonly used are available in
. For other materials, Z-Ratio can be calculated from the following
formula:
[3]
[4]
where:
d
f
= Density (g/cm
3
) of deposited film
µ
f
= Shear modulus (dynes/cm
2
) of deposited film
d
q
= Density of quartz (crystal) (2.649 g/cm
3
)
µ
q
= Shear modulus of quartz (crystal) (3.32 x 10
11
dynes/cm
2
)
The densities and shear moduli of many materials can be found in a number of
handbooks.
Laboratory results indicate that Z-Ratio values of materials in thin-film form are very
close to the bulk values. However, for high stress producing materials, Z-Ratio
values of thin films are slightly smaller than those of the bulk materials. For
applications that require more precise calibration, the following direct method is
suggested:
1
Establish the correct density value as described in
2
Install a new crystal and record its starting frequency, F
co
. The starting
frequency will be displayed in the Freq (Hz) field of the Sensor-Output window.
3
Make a deposition on a test substrate such that the percent crystal life display
will read approximately 50%, or near the end of crystal life for the particular
material, whichever is smaller (the accuracy of the Z-Ratio determination will
improve with increased material thickness).
Z
d
q
q
d
f
f
------------
1
2
---
=
Z
9.378 10
5
d
f
f
-
1
2
---
=