Senior Design II
Film Thickness Measurement
P06402
Julian Peters
Joe Fitzmyer
Brad Demers
Coordinator: Dr. Wayne Walter
Advisor: Dr. Dale Ewbank
Sponsor: Dr. Satish Kandlikar
Agenda
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Project Overview & Background
Interferometry Background
Analysis
System Operation
System Design
Specifications
Design Challenges
Test Plans
Completion Plans
Project Overview – Sponsor’s
Major Needs

Ability to determine existence and thickness
of film
 Cost-effectiveness
 Ability to operate in a “dirty” environment
 Accuracy, but not as demanding as
semiconductor applications
 Must be able to take measurement quickly
 Must not require constant input from user
Project Overview Background

Meniscus Experiment in RIT Thermal
Analysis Lab
Figure 1: Moving Meniscus Experiment
Figure 2: Heater surface and water nozzle detail
Project Overview Background


Meniscus Experiment in RIT Thermal Analysis Lab
Meniscus Experiment in RIT Thermal Analysis Lab – Unanswered Questions:
– Is there a film of adsorbed water left behind the moving meniscus?
– How far does it extend?
– What is its thickness?
Advancing contact
line
Receding contact line
Heated, rotating copper cylinder
Direction of Rotation
Meniscus
Figure 3: Operation of experiment
Interferometry in a Nutshell
4) The recombined beam is collected at a sensor.
The intensity is measured, and can be compared to
the intensity of the original beam.
qi
1) Light is emitted
from the laser diode.
Film Surface
Substrate Surface
3)The two reflected beams recombine. The difference in
the path length taken by the two beams manifests itself as a
phase difference, which can cause attenuation of the beam
intensity.
2) Two reflections take place: part of the
beam reflects from the film surface, part of it
continues through the film and reflects from
the substrate surface.
Figure 5: Interferometry Basics
Interferometry Analysis
for s-polarization
for p-polarization
for s-polarization
for p-polarization
Analysis of Design

MATLAB code written to simulate
reflectance response
 Data from numerical experiments
– Determine appropriate wavelengths
– Analyze experimental data

Most easily identified noise independent
parameter of data is the frequency of
oscillations
Sample MATLAB Results
=635 nm, s-polarization
1
film thickness=1 m
film thickness=10 m
film thickness=50 m
0.95
0.9
0.85
Relative intensity
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0
10
20
30
40
50
Angle of Incidence, degrees
60
Figure 10: Oscillatory Reflectance Response
70
80
90
Sample MATLAB Results
=635 nm, s-polarization
1
film thickness=0 m
0.95
0.9
0.85
Relative intensity
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0
10
20
30
40
50
Angle of Incidence, degrees
60
70
Figure 11: Non-Oscillatory Reflectance Response at Zero Film Thickness
80
90
MATLAB Code Verification
Rs for 10 micron layer, 633 nm light
1
WVASE
MATLAB
0.95
Rs
0.9
0.85
0.8
0.75
0.7
0
10
20
30
40
50
60
70
Angle of Incidence (deg)
Figure 12: Comparison of WVASE32 and MATLAB Results
80
90
Basic System Diagram
Control Hardware
Goniometer
Actuators
Information
Control
Laser Diode Power
Operator
PC
Light reflected
from surface
LabView Data
Collection Hardware
Photosensor
Figure 6: Information and control flow through system
Off-the-Shelf Components
•Laser diode: CPS196
•Photodiode: SM05PD1A
•Goniometers: GNL10-Z6
•Motor Controller: ODC001
•NI USB DAQ 6008
•TI OPA129U
Purchased Components
Purchased Components
Supplier
Thorlabs
Thorlabs
Thorlabs
Thorlabs
Thorlabs
Edmund Optics
Edmund Optics
National Instruments
Grand Total
Part
ODC-001
GNL10-Z6
CPS196
LDS1
SM05PD1A
NT53-830
NT46-573
USB-6008
Description
Number Unit Price Line Total
Motor Controller
2 $598.00 $1,196.00
Motorized Goniometer
2 $435.00 $870.00
Laser Diode Module
1 $143.00 $143.00
Power Supply
1
$79.00
$79.00
Photodiode
1
$48.00
$48.00
Bench Plate
1
$75.00
$75.00
Polarizing Filters
3
$26.70
$80.10
Data Acquisition System
1 $145.00 $145.00
$2,636.10
System Design
Physical System Assembly
Photodiode
Servo Controller
Goniometer
Servo Controller
Substrate and Film
Breadboard Base
Laser Diode
System Design
Physical System Assembly
Goniometer
Servo Controller
Servo Controller
Substrate and Film
Breadboard Base
Base
Specifications & Targets
Positioning Accuracy – ± 0.25°
 Positioning Precision – ± 0.25°
 Film Thickness Accuracy – ± 5 μm
 Film Thickness Precision – ± 5 μm
 Measurement Time – 30 minutes

Design Challenges

Light Source
– Beam divergence
– Suitability of wavelength to film thickness
– Consistency of intensity
– Polarization intensity
– Focal length

Photodiode
– Must accommodate beam divergence
– Accuracy
Design Challenges

Positioning Equipment
–
–
–
–

Accuracy
Repeatability
Synchronicity
Alignment
Equipment Mounts
– Accuracy
– Compensating
Design Challenges

PC Interface Hardware / Software
– Position control and reporting
– Single user input
– Collect data from photodiode

Data Interpretation Programming
– Fit data to simulation
– Measure of confidence
Design Challenges

Specific Application to Mensicus
Experiment
– Optical properties of surface
– Beam alignment
– Flatness of surface
Alignment and Calibration

Goniometer zeroes
 Calibration curve
 Verify alignment
Alignment and Calibration
“Zero” is found by
reflecting laser back
onto itself.
51”
q
Linear-to-angular step
size is found by
making marks on target
at regular linear steps.
Alignment and Calibration
Sensor Goniometer Calibration
10
y = 1.4729x - 9.4451
R2 = 1
8
Goniometer Angle (deg)
6
4
2
0
0
2
4
6
-2
-4
-6
-8
-10
Actuator Position (mm)
8
10
12
Alignment and Calibration
Laser Goniometer Calibration
9
y = 1.5158x - 10.235
R2 = 1
7
Goniometer Angle (deg)
5
3
1
-1 0
2
4
6
-3
-5
-7
-9
-11
Actuator Position (mm)
8
10
12
Test and Completion Plan

Verify assembly alignment
 Labview code
 Test against known films
 Implement Matlab code
 User manual
Any Questions?
CPS196 Datasheet
=405 nm, s-polarization
1.4
film thickness=1 m
film thickness=10 m
film thickness=25 m
1.2
1
Relative intensity
0.8
0.6
0.4
0.2
0
0
10
20
30
40
50
Angle of Incidence, degrees
60
70
80
90
=635 nm, s-polarization
1
film thickness=1 m
film thickness=10 m
film thickness=25 m
0.9
0.8
0.7
Relative intensity
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
Angle of Incidence, degrees
60
70
80
90
=785 nm, s-polarization
1
film thickness=25 m
film thickness=50 m
film thickness=100 m
0.95
0.9
0.85
Relative intensity
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0
10
20
30
40
50
Angle of Incidence, degrees
60
70
80
90
=830 nm, s-polarization
1
film thickness=1 m
film thickness=10 m
film thickness=25 m
0.95
Relative intensity
0.9
0.85
0.8
0.75
0
10
20
30
40
50
Angle of Incidence, degrees
60
70
80
90
Rs for 50 micron layer, 633 nm light
1
WVASE
MATLAB
0.9
0.8
Rs
0.7
0.6
0.5
0.4
0
10
20
30
40
50
Angle of Incidence (deg)
60
70
80
90
Rp for 1 micron layer, 400 nm light
1
WVASE
MATLAB
0.9
0.8
0.7
Rp
0.6
0.5
0.4
0.3
0.2
0.1
0
10
20
30
40
50
Angle of Incidence
60
70
80
90
Rp for 1 micron layer, 633 nm light
1
WVASE
MATLAB
0.95
0.9
0.85
Rp
0.8
0.75
0.7
0.65
0.6
0.55
0.5
0
10
20
30
40
50
Angle of Incidence (deg)
60
70
80
90
Rp for 10 micron layer, 400nm light
1
WVASE
MATLAB
0.9
0.8
0.7
Rp
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
Angle of Incidence (Degrees)
60
70
80
90
Rp for 10 micron layer, 633 nm light
1
WVASE
MATLAB
0.9
Rp
0.8
0.7
0.6
0.5
0.4
0
10
20
30
40
50
Angle of Incidence
60
70
80
90
Rp for 50 micron layer, 400 nm light
1
WVASE
MATLAB
0.9
0.8
0.7
Rp
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
Angle of Incidence (deg)
60
70
80
90
Rp for 50 micron layer, 633 nm light
1
WVASE
MATLAB
0.9
0.8
Rp
0.7
0.6
0.5
0.4
0.3
0.2
0
10
20
30
40
50
Angle of Incidence (deg)
60
70
80
90
Rs for 1 micron layer, 400 nm light
1
WVASE
MATLAB
0.9
0.8
0.7
Rs
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
Angle of Incidence (deg)
60
70
80
90
Rs for 1 micron layer, 633 nm light
1
WVASE
MATLAB
0.98
0.96
Rs
0.94
0.92
0.9
0.88
0.86
0
10
20
30
40
50
Angle of Incidence
60
70
80
90
Rs for 10 micron layer, 400 nm light
1.4
WVASE
MATLAB
1.2
1
Rs
0.8
0.6
0.4
0.2
0
0
10
20
30
40
50
Angle of Incidence
60
70
80
90
Rs for 10 micron layer, 633 nm light
1
WVASE
MATLAB
0.95
Rs
0.9
0.85
0.8
0.75
0.7
0
10
20
30
40
50
Angle of Incidence (deg)
60
70
80
90
Rs for 50 micron layer, 400 nm light
1
WVASE
MATLAB
0.9
0.8
0.7
Rs
0.6
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
40
50
Angle of Incidence (deg)
60
70
80
90
Control VI
Part Prints
Sensor-Side Mount
Laser Mount
Sensor Mount
Sample Platform
System Operation
User initializes the
measurement through
a simple GUI
LabView controller inputs position
data to motor controllers
Controllers position
goniometers at a range of
angle increments
DAQ measures light intensity incident
on photodiode at each position
LabView plots captured data and outputs
measured thickness as well as error or
confidence level of the measurement