Inficon SQC-310 User Manual

7 - 4
PN 074-550-P1C
SQC-310 Operating Manual
6 Using the density value from step 1 and the recorded values for F
co
and F
c
,
adjust the Z-Ratio value in thickness equation [5] to bring the calculated
thickness value into agreement with the actual thickness. If the calculated value
of thickness is greater than the actual thickness, increase the Z-Ratio value. If
the calculated value of thickness is less than the actual thickness, decrease the
Z-Ratio value.
[5]
where:
 T
f
= Thickness of deposited film (kÅ)
 F
co
= Starting frequency of the sensor crystal (Hz)
 F
c
= Final frequency of the sensor crystal (Hz)
 F
q
= Nominal blank frequency = 6045000 (Hz)
 z = Z-Ratio of deposited film material
 Z
q
= Specific acoustic impedance of quartz = 8765000 (kg/(m
2
s)
 p = Density of deposited film (g/cm³)
For multiple layer deposition (for example, two layers), the Z-Ratio used for the
second layer is determined by the relative thickness of the two layers. For most
applications the following three rules will provide reasonable accuracies:
 If the thickness of layer 1 is large compared to layer 2, use material 1 Z-Ratio
for both layers.
 If the thickness of layer 1 is thin compared to layer 2, use material 2 Z-Ratio for
both layers.
 If the thickness of both layers is similar, use a value for Z-Ratio which is the
weighted average of the two Z-Ratios for deposition of layer 2 and subsequent
layers.
T
f
Z
q
10
4

2zp
--------------------
1
F
co
--------


ATan zTan
F
co
F
q
-----------




1
F
c
-----


ATan zTan
F
c
F
q
---------




–



=

Inficon SQC-310 Specifications

General

Brand	Inficon
Model	SQC-310
Category	Controller
Language	English