Senior Design II Film Thickness Measurement Julian Peters Joe Fitzmyer Brad Demers Coordinator: Dr. Wayne Walter Advisor: Dr. Dale Ewbank Sponsor: Dr. Satish Kandlikar P06402

Agenda 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 ExperimentFigure 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? Figure 3: Operation of experiment Heated, rotating copper cylinder Meniscus Direction of Rotation Advancing contact line Receding contact line

ii Film Surface Substrate Surface 1) Light is emitted from the laser diode. 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. 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. 4) The recombined beam is collected at a sensor. The intensity is measured, and can be compared to the intensity of the original beam. Interferometry in a Nutshell 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 Figure 10: Oscillatory Reflectance Response

Sample MATLAB Results Figure 11: Non-Oscillatory Reflectance Response at Zero Film Thickness

MATLAB Code Verification Figure 12: Comparison of WVASE32 and MATLAB Results

Basic System Diagram Figure 6: Information and control flow through system PC Control HardwareGoniometer Actuators Laser Diode Power PhotosensorLabView Data Collection Hardware Operator Light reflected from surface Information Control

Off-the-Shelf Components Laser diode: CPS196Goniometers: GNL10-Z6 Photodiode: SM05PD1A Motor Controller: ODC001 NI USB DAQ 6008 TI OPA129U

Purchased Components

System Design Physical System Assembly Servo Controller Goniometer Breadboard Base Substrate and Film Servo Controller Photodiode Laser Diode

System Design Physical System Assembly Servo Controller Goniometer Breadboard Base Base Substrate and Film Servo Controller

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. Linear-to-angular step size is found by making marks on target at regular linear steps. 51” 

Alignment and Calibration

Test and Completion Plan Verify assembly alignment Labview code Test against known films Implement Matlab code User manual

Any Questions?

CPS196 Datasheet

Control VI

Part Prints

Sensor-Side Mount

Laser Mount

Sensor Mount

Sample Platform

System Operation User initializes the measurement through a simple GUI Controllers position goniometers at a range of angle increments DAQ measures light intensity incident on photodiode at each position LabView controller inputs position data to motor controllers LabView plots captured data and outputs measured thickness as well as error or confidence level of the measurement