microforce™ probing for devices with low k ild materials• used tel’s pcms to evaluate probe...

MicroForce™ Probing for Devices MicroForce™ Probing for Devices with Lowwith Low--k ILD Materialsk ILD Materials

Rod Martens, Ph.D., FormFactor, Inc.Rod Martens, Ph.D., FormFactor, Inc.

Abdel Abdelrahman, Intel CorporationAbdel Abdelrahman, Intel Corporation

Steve Martinez, Tokyo Electron LimitedSteve Martinez, Tokyo Electron Limited

Southwest Test Conference, Long Beach, CASouthwest Test Conference, Long Beach, CA

June, 2003June, 2003

2SouthWest Test Conference June, 2003

ContentsContents

Introduction to MicroForce™ Probing TechnologyIntroduction to MicroForce™ Probing Technology–– Industry Requirements for Probing Flip Chip Bump Devices Industry Requirements for Probing Flip Chip Bump Devices

–– Probe Card ArchitectureProbe Card Architecture

–– MicroForce Probing DefinitionMicroForce Probing Definition

FormFactor Lab DevelopmentFormFactor Lab Development–– Single Probe Testing of Force and CresSingle Probe Testing of Force and Cres

Sort Floor ValidationSort Floor Validation–– Force MeasurementsForce Measurements

–– Probe Mark ComparisonsProbe Mark Comparisons

–– Cres and Probe Conditions After Aging TestCres and Probe Conditions After Aging Test

ConclusionsConclusions


Industry Requirements for Probing Industry Requirements for Probing Advanced Flip Chip Bumped DevicesAdvanced Flip Chip Bumped Devices

Lower Force ProbingLower Force Probing–– LowLow--k ILD materials are more fragilek ILD materials are more fragile

–– Low probe force desired to minimize damage to flip chip bump Low probe force desired to minimize damage to flip chip bump and ILD materialsand ILD materials

Low and Consistent Contact ResistanceLow and Consistent Contact Resistance–– High frequency and high power applications require tighter Cres High frequency and high power applications require tighter Cres

controlcontrol

–– Applications require higher current to pass through probe Applications require higher current to pass through probe system without much resistancesystem without much resistance

Finer PitchFiner Pitch–– Roadmap to 100Roadmap to 100µµm pitch requires revolutionary probing m pitch requires revolutionary probing

approachapproach


FormFactor BladeRunner™ Probe Cards FormFactor BladeRunner™ Probe Cards (For Probing Bumped Wafers)(For Probing Bumped Wafers)


FormFactor Probe Card ArchitectureFormFactor Probe Card ArchitectureControlled Impedance Tester Interface

PCB Assembly

InterposerWith MicroSpring

Contact

Space Transformer:

MicroSpring™ Contact for Probing Flip Chip Bumps


MicroForceMicroForce™™ Probing DefinitionProbing Definition

What is MicroForce™ probing?What is MicroForce™ probing?–– It is a coordinated XIt is a coordinated X--YY--Z probing motionZ probing motion

–– Developed to satisfy a number of stringent requirements for Developed to satisfy a number of stringent requirements for probing devices with lowprobing devices with low--k ILD materialsk ILD materials

–– Breakthrough results with 10:1 reduction of probe force yet Breakthrough results with 10:1 reduction of probe force yet achieving consistent and low contact resistanceachieving consistent and low contact resistance

1 – Prober Chuck Moves in Z-axis2 – Contact with Flip Chip Bump3 – Chuck moves in X-Y-Z

1

2

3


MicroForce™ Probing on MicroForce™ Probing on PbPb//SnSn BumpBump

MicroSpring™ ContactProbing onHigh-Pb Bump

MicroForce™ Probing Motion

Chuck Translation Direction

FormFactor Laboratory DevelopmentFormFactor Laboratory Development


TEL Synchronous XYZ DriveTEL Synchronous XYZ Drive

3D drive control method(Synchronous 3D Drive)(Synchronous 3D Drive)

TargetPosition

TsTime

1Drive

Start

Servo DriverServo Driver

Stepping Driver M

ControlPosition

Data

M

MHOST

XYZ Motion Contact

Benefits• Increased throughput with simultaneous XYZ drive• Smooth drive creates desired probe contact

SimultaneousXYZ Drive


Experimental Setup Experimental Setup -- Predictive ProbingPredictive Probing

Force/Displacement Fixture

Test Wafer

Micro-ohmmeter(4-wire)

Data Acquisition

ForceDisplacement

Resistance

Test Spring


Significantly Lowered Probe Force with Significantly Lowered Probe Force with MicroForce FeatureMicroForce Feature

0

2

4

6

8

10

12

14

0 0.001 0.002 0.003

Over-Travel (Inch)

Load

(Gra

ms)

S.R. = 0.0S.R. = 0.5S.R. = 1.0S.R. = 1.5S.R. = 2.0

Scrub Ratio =Movement in X/YMovement in Z


Repeatability of Cres Study on Pb/Sn BumpsRepeatability of Cres Study on Pb/Sn Bumps

Stable and Low Contact Resistance with MicroForce Probing

Sort Floor ValidationSort Floor Validation


Outline of Outline of PProbe card robe card CCharacteristics haracteristics MMeasurement easurement SSystemystem

DefinitionPCMS is a measurement system that can measure the probe card displacement under load.The result of PCMS includes the displacement of head plate, probe card and probe card holder.

0.0 um0.0 um

0.0 kg

Test Head

Probe card

Load sensor

Digital displacement sensor (Multiple)Chuck

Guide rail ofalignment bridge

Front sensor

Rear sensor

Leftsensor

Rightsensor

Sensor layout

Head plate


Low Probing Force Using MicroForce FeatureLow Probing Force Using MicroForce Feature

• Used TEL’s PCMS to evaluate probe card deflection under varying loads. Data generated included actual spring compression and probing force per dialed chuck motion.

• Max probing force = 13N at 80µm of spring over-travel

• Max force/probe = 0.3g/mil with MicroForce vs. 3 – 4g/mil without MicroForce

0

2

4

6

8

10

12

14

0 10 20 30 40 50 60 70 80 90

O T ( u m )

Forc

e ( N

)

A vg F orc e


Probing of Microprocessor DevicesProbing of Microprocessor Devices

TestingTesting–– Sort tests were run with and without MicroForce probing Sort tests were run with and without MicroForce probing

–– Correlation of device binning and other parametric indicators Correlation of device binning and other parametric indicators measuredmeasured

–– 3 production lots of microprocessor devices were tested3 production lots of microprocessor devices were tested

ResultsResults–– Binning data collected under MicroForce had a correlation rate oBinning data collected under MicroForce had a correlation rate of f

95.9 95.9 –– 97.4% vs. existing probing Recipe (target is >95%)97.4% vs. existing probing Recipe (target is >95%)

–– Other parametric measurements indicated comparable resultsOther parametric measurements indicated comparable results

–– No issues in terms of the mechanical and electrical behavior of No issues in terms of the mechanical and electrical behavior of the springs under MicroForce Probing. Metrology data remained the springs under MicroForce Probing. Metrology data remained within the defined specifications.within the defined specifications.


Probe Mark ComparisonProbe Mark Comparison

Pb/Sn BumpPb/Sn Bump

Standard Probing MicroForce Probing


Validation of MicroForce Low CresValidation of MicroForce Low Cres

0.08980.0898

0.12560.1256

0.14920.1492

0.34660.3466

Mean Mean

0.0200.020

0.0240.024

0.0230.023

0.0470.047

Std DevStd Dev

7070

5050

3535

1515

POT umPOT um• Good convergence of Cres

• Mean Cres at different programmable ovetravels: 0.1 – 0.35Ω

• Enabling a wide manufacturing process window

0

0.1

0.2

0.3

0.4

0.5

35µm POT0

0.1

0.2

0.3

0.4

0.5

50µm POT0

0.1

0.2

0.3

0.4

0.5

70µm POT0

0.1

0.2

0.3

0.4

0.5

Ω

15µm POT


MicroSpring Contact After Aging TestMicroSpring Contact After Aging Test

After 500,000 Touchdowns

New (after probing 6 wafers)


Cres Stability After Aging TestCres Stability After Aging TestUnder MicroForce Probing, Cres remained stable for 500K touchdowns

0.000

0.100

0.200

0.300

0.400

0.500

0.600

1 525 1049 1573 2097 2621

Die, Wafer

Die

Ave

Cre

s ( O

hm )

5k TD 100k TD 200k TD 300k TD 400k TD 500k TD


ConclusionsConclusions

MicroForce Technology provided new capabilities to meet MicroForce Technology provided new capabilities to meet newnew--generation probing requirements. generation probing requirements.

MicroForce Probing offered low contact resistance necessary MicroForce Probing offered low contact resistance necessary for high power delivery requirements.for high power delivery requirements.

MicroForce Probing delivered very low probing force (<2g) MicroForce Probing delivered very low probing force (<2g) thus minimizing the risk to damage die with lowthus minimizing the risk to damage die with low--k ILD k ILD materials.materials.

Sort on production devices proved very stable and correlated Sort on production devices proved very stable and correlated to existing probing recipes. The solution satisfies Intel to existing probing recipes. The solution satisfies Intel probing requirements.probing requirements.

Future work will be targeted at:Future work will be targeted at:–– Throughput OptimizationThroughput Optimization–– Production Sort Certification Production Sort Certification


AcknowledgmentAcknowledgment

The authors would like to thank the following contributors who The authors would like to thank the following contributors who made the MicroForce Probing development possible:made the MicroForce Probing development possible:

Tim CooperTim Cooper FormFactorFormFactor

GeneGene Kochert Kochert IntelIntel

Koichi Koichi Matsuzaki Matsuzaki TELTEL

Lance MilnerLance Milner IntelIntel

JesseJesse Nuanez Nuanez IntelIntel

Weida QianWeida Qian IntelIntel

Scott Scott ScofieldScofield IntelIntel

Rick Rick TakebuchiTakebuchi TELTEL

Dilip WadhwaniDilip Wadhwani IntelIntel

SunilSunil WijeyesekearaWijeyesekeara FormFactorFormFactor

microforce™ probing for devices with low k ild materials• used tel’s pcms to evaluate probe...

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