FABRICATION, CALIBRATION AND
CHARACTERIZATION OF MICRO-SCALE
RESISTANCE TEMPERATURE
DETECTORS(RTD’s)
KUNJAN CHAUDHARI
AdvisorDr. Hyejin MoonCommittee MembersDr. Hyejin MoonDr. Miguel AmayaDr. Donghyun Shin
IMNfL
INTEGRATED MICRO/NANOFLUIDICs LAB
OUTLINE2
• Introduction
– Resistance Temperature Detector and its features.
• Motivation
• Experimental details
– Design of RTD
– Experimental Setup
– LabVIEW Setup with flowchart
• Indium Tin Oxide
– Fabrication
– Literature Review
– Conclusion and Results
• Nickel
– Fabrication
– Results
– Conclusions
• Conclusions
• Future work
RESISTANCE TEMPERATURE
DETECTOR• Resistance Temperature Detectors are temperature sensors that contain a resistor
that changes resistance value as its temperature changes.
• Many conductive materials change resistance with the change in temperature.
• Common RTD sensing elements have a repeatable resistance versus temperaturerelationship (R vs T) and operating temperature range.
R=Rref[1+α(T-Tref)]Where,R= Resistance at temperature “T”.Rref= Resistance at reference temperature (usually 21˚C)α=Temperature Co-efficient of Resistivity for the sensor.T=Unknown Temperature to be measured.Tref=Reference Temperature taken (21˚C).
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Thin Film RTD
Wire wound RTD
FEATURES OF RTD
Applications• Air conditioning and
refrigeration • Food Processing• Textile production• Petrochemical processing• Micro electronics• Air, gas and liquid
temperature measurement.• Laboratory temperature
measurements.• Temperature measurements
in Aircrafts .• Medical devices.• Microfluidics.
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When to use RTD?• For accuracy and stability requirements.• For accuracy over a wide temperature range.• When immunity to electrical noise is desired. • For a high degree of standardization.
Advantages • Linearity over wide operating range• High temperature operating range• Repeatability.• Good stability at high temperature.• Accuracy
MOTIVATION
• Resistive Temperature Detectors were used by Shreyas for measuring temperature of Droplet in his study of Digital EWOD.
• Indium Tin Oxide provides optical transparency.• Ease of integration in microfluidic devices .• Ease in fabrication .• Suitable material for EWOD patterning (electrodes).
EWOD
Electrode
RTD
HeaterCredit: Shreyas
Bindiganavale, PhD
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Credit:
Shreyas Bindiganavale, PhD
ITO Resistance vs Temperature Curve
GOALS OF RESEARCH
• Fabrication ,calibration and characterization of micro-scale resistance temperaturedetector (RTD) for measuring temperature at micro level.
• Structural change in material due to Heat treatment and its effect on theperformance of RTD.
• Identifying the limitation of RTD.
• Create a final Recipe for fabrication of RTD’s in EWOD platforms.
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RTD DESIGN
Thickness of RTD material:
1. ITO= 200 nm
2. Nickel = 100 nm
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RTD Design
Our substrate is Glass with 700µm thickness.
Side view of Device
RTD/Heater on glass substrate
Glass Substrate
RTD material
EXPERIMENTAL SETUP• Heat Source – Fisher Scientific ISOTEMP Hot Plate.
• Data measurement – Agilent 34980A Data Acquisition System.
• Software – NI LabVIEW 2015.
• Temperature measurement – Thermocouples (‘K’ type , ‘J’ type).
• Connecting Wires – Copper wires.
• Device – Clean room fabricated – ITO RTD and Nickel RTD.
• Oil used-Valvoline SAE 0W-20.
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K-type Thermocouple
Schematic of the Experimental setup
Thermocouple 3
Thermocouple 1
Thermocouple 2
OIL BATH
DAQ
Computer with LabVIEW
Container with InsulationHOT PLATE
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• Oil Bath calibration Technique for calibration of RTD.
– For steady state temperature.
– To maintain uniformity of temperature on entire surface of RTD.
– Better temperature control.
– Inertness to the materials.
• Advantages of motor oil
– Relatively High boiling point.(300˚C).
– For Calibration at higher ranges of temperatures.
– The value for Thermal Time Constant is very small.
– Commercially available.
OIL BATH CALIBRATION
www.popularmechanics.com
EXPERIMENTAL SETUP
System for Data Acquisition Agilent 34980A
Hot Plate
Oil Bath with Hot Plate
Computer with LabVIEW
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FLOWCHART OF CALIBRATION
ThermocouplesRTD
INITIALIZING CONFIGURE MEASUREMENT
MEASURING OUTPUT TO DISPLAY
DATA ACQUISITION HARDWARE
OIL BATH
Timed Loop
LABVIEW PROGRAM
DATA ACQUISITION SYSTEM
Ref. Temperature for Thermocouples
4-Wire Resistance Measurement
Graphs
Numeric
Activation of DAQ
Arrangement of channels
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LABVIEW PROGRAM
Credit: LABVIEW
INITIALIZE VI
Configure Measurement VI
Measurement VI
Output VI
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INDIUM TIN OXIDE• Indium tin oxide is a mixture of indium(III) oxide (In2O3) and tin(IV) oxide
(SnO2), typically 90% In2O3, 10% SnO2 by weight.
• An electrode having good conductivity.
• Provides optical transparency.
• Ease in fabrication and patterning.
• Thin films are deposited on surfaces by physical vapor deposition, electronbeam deposition or a range of sputter deposition techniques.
• Applications in LCD, OLED, plasma screen , touch screens, aircraft windshields ,Photovoltaic Solar Cells , Electron Circuitry.
Credit : INDIUM CORPORATIONCredit : www.adafruit.com
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ITO CLEAN ROOM FABRICATION
ITO Heater/RTD fabrication
1)
2)
3)
4)
5)
GLASS SUBSTRATE
ITO
HMDS
PHOTORESIST
Spin Coating HMDS and PR
Lithography and Developing
ITO etching
PR Stripping
Magnified Resistance Path
Fabricated ITO RTD/Heater
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LITERATURE REVIEWHiroshi Morikawa , M. Fujita, Crystallization and electrical property change on the annealing of amorphous indium-oxide and indium-tin-oxide thin films, Thin Solid Films 359 (1999) 61-67.Hiroshi Morikawa ,H . Sumi , M. Kohyama , Crystal growth of ITO films prepared by DC magnetron sputtering on C film , Thin Solid Films 281-282 (1996) 202
Credit: H. Morikawa et. al
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• H. Morikawa et al. investigated the behavior of ITO filmson substrate.
• The film is almost amorphous including a small amountof nuclei, most of which are generated directly on thesubstrate surface during deposition.
• Observed that ITO changes its crystal structure whensubjected to high temperatures.
• Decrease in Resistivity because of increase in carrier concentration supplied by Sn atoms which became active at high temperatures.
ANNEALED ITO (2 HOURS at 200˚C)
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CONCLUSION FROM THE EXPERIMENTS
• Partial Crystallization of ITO after 2 hours of Annealing.
• Non-linear Temperature v/s Resistance Curve.
• Multiple tests didn’t give repeatable results.
• Increasing the Annealing time may fully crystallize the ITO grain structure.
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Credit: H. Morikawa,M. Fujita
a)at 150˚C,b)at 210˚C ,c)at 240˚C
LITERATURE REVIEW
• Paine et al. observed ITO thin film usingTEM technique and found that as-deposited ITO film has a fully amorphousstructure.
• After annealing in air at 162 °C, the samplebecomes crystalline consisting of largeblock-like grains that are, on average,approximately 100 nm in size.
• The Resistivity of the material changesbecause of relaxation of distorted bonds inthe as-deposited amorphous material.
Credit: David C Paine et el.
Credit: David C Paine et el.
Credit: Paine et.al, A study of low temperature crystallization of amorphous thin film indium-tin-oxide , J Appl. Phys. , Vol. 85,No. 12,15 June 1999
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ANNEALED ITO (8 HOURS at 200˚C)
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CONCLUSION FROM EXPERIMENTS
• No considerable change observed after increasing the time of Annealing.
• Partial Crystallization of ITO.
• Non-linear Temperature vs Resistance Curve.
• Multiple tests didn’t give repeatable results.
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LITERATURE REVIEW
• K.L. Fang et.al observed that after annealing at 150˚C for the ITO sample givesrelatively very less change in its resistivity.
• U.Betz et.al in their research concluded that :
- At 150 °C the thermal activation induces the structural relaxation mechanism, resultingin an initial decrease of the resistivity value.
- Crystallization process begins at 150 °C.
Credit: U. Betz et al
Credit: K. L. Fang et al
• Credits: U. Betz et.al, Thin films engineering of indium tin oxide: Large area flat panel displays application, Surface & Coatings Technology 200(2006) 5751-5759
• Credits: K.L. Fang et.al , Low Temperature Crystallization of Indium-tin-oxide
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NON-ANNEALED ITO RTD22
RESISTANCE V/S TEMPERATURE CURVE
FOR ITO
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THIN FILM NICKEL
• Well known material of choice for RTD construction.
• Have a known and linear positive Temperature v/s resistance characteristics under 300˚C.
• Cost-effective and remains stable in harsh oxidizing environment.
• A good compromise between copper and platinum.
• Ease in fabrication.
Credit : www.heraeus.comCredit: www.William-Rowland.com
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NICKEL CLEAN ROOM FABRICATION
• Piranha Solution cleaning prior to deposition
• Nickel was also encapsulated with a layer of Di-electric.
• Anneal at 200˚C for two hours2)
3)
4)
5)
6)
GLASS SUBSTRATENICKEL
HMDSPHOTORESIST
Spin Coating HMDS and PR
Lithography and Developing
Nickel etching
PR Stripping
E-Beam Deposition1)
7)
Su-8 layerSu-8 spin coating
Nickel RTD fabrication
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Fabricated Nickle RTD
NICKEL RTD/HEATERS
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RESISTANCE v/s TEMPERATURE PLOT FOR
NICKEL RTD
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RESULTS AND CONCLUSIONS
Annealing
Conditions
Nature of Plot Repeatable Resistivity(ρ)(in Ω-
cm)
TCR
(/˚C)
Operating
Temperature
ITO
2 Hours @
200˚C
Non-linear No 2.3*10^-4 N/A N/A
8 Hours @
200˚C
Non-linear No 2.3*10^-4 N/A N/A
Non-annealed Linear Yes 2.3*10^-4 0.0007 22˚C-150˚C
Nickel 2 Hours @ 200˚C Linear Yes 6.11*10^-6 0.004 22˚C-200˚C
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• Indium Tin Oxide can be used as Resistive Temperature Detector under the temperature range of 150˚C when it is Amorphous in nature.
• Annealing plays an important role in changing the state from amorphous to crystalline.
• Nickel can be used as RTD for a greater range of temperatures after Annealing and using a passivation layer.
FUTURE WORK
• Studying of behavior of ITO with different deposition technique.
• Calibrating ITO RTD for Very High Temperatures.
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REFERENCES
• [1] Hiroshi Morikowa, M. Fujita, Crystallization and electrical property change on the annealing of amorphous indium-oxide and indium-tin-oxide thin films, Thin Solid Films 359 (1999) 61-67.
• [2] Hiroshi Morikawa ,H . Sumi , M. Kohyama , Crystal growth of ITO films prepared by DC magnetron sputtering on C film , Thin Solid Films 281-282 (1996) 202
• [3]U. Betz et.al, Thin films engineering of indium tin oxide: Large area flat panel displays application, Surface & Coatings Technology 200(2006) 5751-5759
• [4]Paine et.al, A study of low temperature crystallization of amorphous thin film indium-tin-oxide , J Appl. Phys. , Vol. 85,No. 12,15 June 1999
• [5] K.L. Fang et.al , Low Temperature Crystallization of Indium-tin-oxide
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ACKNOWLEDGEMENT
• I would like to thank Dr. Hyejin Moon, for providing me opportunity , investing her valuable time in training me and for her encouragement throughout this research thesis.
• I would also like to thank Arvind Venkatesan, Ali Farzbod , Shubhodeep Paul and MunMun Nahar for guiding and supporting me throughout the research study.
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QUESTIONS?
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