Thermal Imaging Test ChipThermal Imaging Test Chip

Justin I. QuesnelJustin I. Quesnel

08/18/0508/18/05

ObjectiveObjective

Previous WorkPrevious Work

Chip DesignChip Design

Chip Test and ResultsChip Test and Results

PhotosPhotos

Q & AQ & A

OutlineOutline

Project ObjectiveProject Objective

To develop an ideal test structure to prove To develop an ideal test structure to prove the theoretical limits of subsurface thermal the theoretical limits of subsurface thermal imaging resolution with a Numerical imaging resolution with a Numerical Aperture Increasing Lens (NAIL).Aperture Increasing Lens (NAIL).

Numerical Aperture Increasing Numerical Aperture Increasing Lens (NAIL) backgroundLens (NAIL) background

Plano-convex lens of the same materialPlano-convex lens of the same material Silicon, n = 3.5Silicon, n = 3.5

Without a NAIL, 2.5um Without a NAIL, 2.5um

With a NAIL, .73um With a NAIL, .73um Lateral Resolution increaseLateral Resolution increase

by a factor of n = 3.5by a factor of n = 3.5

10X w/NAILBoston Univ.

100X objectiveConventionalState-of-the-art

Previous WorkPrevious Work

First experiment with NAIL enhancementFirst experiment with NAIL enhancement Lateral Resolution of 1.4 um Lateral Resolution of 1.4 um

LimitationsLimitations Feature size not fine enough Feature size not fine enough ElectromigrationElectromigration Unknown maximum current densityUnknown maximum current density Environment not easily controlled/measuredEnvironment not easily controlled/measured

New Chip RequirementsNew Chip Requirements

Test structuresTest structures Different materials/emissivitiesDifferent materials/emissivities Crossing and vertical lines Crossing and vertical lines Varying widthsVarying widths

Internally controlled excitationInternally controlled excitation Frequency and Pulse-widthFrequency and Pulse-width

Temperature ControlTemperature Control

Fabrication SitesFabrication Sites

TradeoffsTradeoffs Cost vs. Feature LengthCost vs. Feature Length Proprietary InformationProprietary Information Submission DatesSubmission Dates

Final DecisionFinal Decision AustriaMicrosystems AustriaMicrosystems

.35 um feature length.35 um feature length 4 metal layers, 2 poly4 metal layers, 2 poly

Software Software

CadenceCadence Design and Electrical SimulationDesign and Electrical Simulation

FemlabFemlab Thermal simulationsThermal simulations

Chip OverviewChip Overview

Chip SectionsChip Sections Samples Samples Pulse GeneratorPulse Generator Thermal NetworkThermal Network PassivesPassives

SpecificationsSpecifications 3.3mm x 3.3mm3.3mm x 3.3mm ~37,000 transistors~37,000 transistors 80 pins80 pins

Sample OverviewSample Overview

TemplateTemplate

Test structuresTest structures M1-M4, P1,P2, M1-M4, P1,P2,

DiffusionDiffusion Crossing, VerticalCrossing, Vertical

Sample – Test Structures Sample – Test Structures

Test StructuresTest Structures Varying Widths Varying Widths

Heating resistorsHeating resistors

Thermal sensorThermal sensor

Sample - ControlSample - Control

Transmission GatesTransmission Gates

Digital Control LogicDigital Control Logic

Driving TransistorsDriving Transistors Max Current DensityMax Current Density

Operating ModesOperating Modes

Pulse GeneratorPulse Generator

Frequency controlFrequency control

Pulse Width Pulse Width ModulationModulation

Test/Bypass Test/Bypass pointspoints

Thermal NetworkThermal Network

Temperature SensingTemperature Sensing Voltage and temperature Voltage and temperature

are linear with a constant are linear with a constant currentcurrent

Biasing and sensingBiasing and sensing Current MirrorsCurrent Mirrors Large mux for toggling Large mux for toggling

between thermal sensorsbetween thermal sensors

Advantage of Temperature ControlAdvantage of Temperature Control

Voltage ControlledVoltage Controlled Heating Resistors in Heating Resistors in

parallelparallel

Ambient temperature Ambient temperature Larger Blackbody Larger Blackbody

RadiationRadiation

Advantage of Pulsed ExcitationAdvantage of Pulsed Excitation

DC vs PulsedDC vs Pulsed

Varying Varying PulsewidthPulsewidth

Fault ToleranceFault Tolerance

Backup structuresBackup structures Completely isolatedCompletely isolated

Test and Bypass Test and Bypass points placed points placed around chiparound chip

Passive StructuresPassive Structures

Microscope Microscope CalibrationCalibration

All layers All layers

Pad Ring DesignPad Ring Design

Flip chip bondingFlip chip bonding Special ConstraintsSpecial Constraints Limited # of pinsLimited # of pins

Two Concentric CirclesTwo Concentric Circles AccessibilityAccessibility

Pad Design and Pad Design and ProtectionProtection

Chip TestingChip Testing

PackagingPackaging Dual Inline Packaged Dual Inline Packaged

Electrical TestingElectrical Testing WirewrappedWirewrapped Digital toggle switchesDigital toggle switches

Sample<0:3>Sample<0:3>First_res<0:3>, First_res<0:3>, Second_res<0:3>Second_res<0:3>Mode_bits<0:1>Mode_bits<0:1>Enable and control bitsEnable and control bitsAnalogAnalog

ResultsResults

Sample - TestSample - Test Passive Resistor TestingPassive Resistor Testing

Toggling through samples and resistorsToggling through samples and resistors Active Resistor TestingActive Resistor Testing

Exciting internally, viewing externallyExciting internally, viewing externally

Varying pulsesVarying pulses

Exciting externallyExciting externally

ResultsResults

Function Generator - TestFunction Generator - Test Ring Oscillator and CounterRing Oscillator and Counter Pulse-Width ModulatorPulse-Width Modulator

Bypassed using external ICsBypassed using external ICs Test and Bypass PointsTest and Bypass Points

ResultsResults

Temperature Network - TestTemperature Network - Test Individual diodeIndividual diode

Varying voltageVarying voltage

~5 Celsius delta~5 Celsius delta Diode networkDiode network

Gradient detected Gradient detected

Susceptibility to neighborsSusceptibility to neighbors

Heat sinks (~2C delta) Heat sinks (~2C delta)

Chip Testing ConclusionChip Testing Conclusion

All units functioningAll units functioning Pulse width modulator is malfunctioningPulse width modulator is malfunctioning

Easily Bypassed with external ICEasily Bypassed with external IC

Ready for next phaseReady for next phase Flip-chip bonding on a PCBFlip-chip bonding on a PCB

Near Infrared ImagesNear Infrared Images

Indium Gallium Arsenide CameraIndium Gallium Arsenide Camera 1200 nm LED array source1200 nm LED array source

Near Infrared ImagesNear Infrared Images

Metal 4 Sample ViewMetal 4 Sample View Top SideTop Side

Obstructed viewObstructed view FlippedFlipped

Near Infrared ImagesNear Infrared Images

Top View of Metal 4 lines Top View of Metal 4 lines

Near Infrared ImagesNear Infrared ImagesSubsurface view of Calibrating LinesSubsurface view of Calibrating Lines

Future Work on ChipFuture Work on Chip

Preparation for thermal imagingPreparation for thermal imaging Die polishingDie polishing Flip-Chip bondingFlip-Chip bonding Thermal image data acquisitionThermal image data acquisition

LimitationsLimitations

Potential enhancements Potential enhancements Larger die = more IO PinsLarger die = more IO Pins More elaborate temperature networkMore elaborate temperature network

Dedicated voltage control pinsDedicated voltage control pins

Wider voltage control netsWider voltage control nets

SummarySummary

Thermal Test ChipThermal Test Chip Consists of ~150 different resistive structuresConsists of ~150 different resistive structures

Digitally ControlledDigitally ControlledControllable frequency/pulsewidthControllable frequency/pulsewidthSeveral Modes of operationSeveral Modes of operationTemperature controlTemperature control

Testing and ResultsTesting and ResultsFully operationalFully operationalReady for thermal imagingReady for thermal imaging

QuestionsQuestions

Near Infrared ImagesNear Infrared ImagesSub surface Analog Section Sub surface Analog Section Current Mirrors and OpampCurrent Mirrors and Opamp

Near Infrared ImagesNear Infrared Images

Top Level Polysilicon Layer 1 SampleTop Level Polysilicon Layer 1 Sample

Near Infrared ImagesNear Infrared ImagesSubsurface view - Digital Control Subsurface view - Digital Control ~2500 transistors~2500 transistors

Near Infrared ImagesNear Infrared Images

Subsurface view Driving PMOS transistors Subsurface view Driving PMOS transistors

Near Infrared ImagesNear Infrared Images

Subsurface view Frequency Control Unit Subsurface view Frequency Control Unit