Pad Damage Management on the Test Floor

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Pad Damage Management on the Test Floor

Applied Precision

ong>Padong> ong>Damageong> ong>Managementong> on

the Test Floor

By John Strom – Lifetime Fellow

June 2006 J. Strom 1


Agenda

• Overview of Test Setup

• General Analysis of Test Data

• Scrub Depth Analysis

• Punch-Through Analysis

• Bump Measurements

• Conclusions

June 2006 J. Strom 2


Testing Overview

• Probe Card –

– 8 Dut

– 1208 Probes

• 300mm Prober / Wafer

• Metrology Tool - waferWoRx300

– Probe Card Measurements - Planarity/Alignment/Diameter

(Optical)

– Wafer Measurements - 2D Scrub Measurements

– Analysis - Correlation / Probing Process Modeling

– 3D Scrub Measurements – Scrub Depth

– 3D Probe Tip Measurements – Tip Profile

– Punch Through Screening

– Bump Measurements

June 2006 J. Strom 3


General Analysis of Test Data

• Probe Card Measurements - (Position and Size)

• Wafer Scrub Measurements - (Position and Size)

• Correlation Analysis

June 2006 J. Strom 4


Scrub Width and Tip Diameter

Probe Tip Diameter – Average = 14.3 microns

Scrub Width - Average = 15.5 microns

Diameter measurements

June 2006 J. Strom 5


Probe Card : Position Measurements

Planarity and Alignment ~ 10 microns

Planarity measurements

Alignment measurements

June 2006 J. Strom 6


Wafer Measurements - XY

• Scrub XY Position - Vector View (Average XY Position per die)

June 2006 J. Strom 7


Wafer Measurements - XY

Scrub XY Position Predicted and Measured– Single Touch Down

June 2006 J. Strom 8


XY Correlation

Scrub XY Position Predicted and Measured– Single Touch Down

June 2006 J. Strom 9


Scrub Depth Analysis Overview

ong>Padong> Material and associated Yield Point

• Probe Tip Shape and Diameter vs Depth

• Scrub Length vs Depth

June 2006 J. Strom 10


ong>Padong> Material and Associated

Yield Point

June 2006 J. Strom 11


Probe Tip Shape / Diameter

Consistent Shape and Size for majority of probes

June 2006 J. Strom 12


3-D Scrub Depth Measurement

Complete 3-D

analysis of scrub

marks

Cross-sectional

analysis allows for

measurement

between any two

points

June 2006 J. Strom 13


Scrub Depth vs Probe Diameter

Consistent Shape and Size caused very little

depth correlation in this data set.

June 2006 J. Strom 14


Scrub Depth vs Scrub Length

Strong correlation between Scrub Length and

Scrub Depth

June 2006 J. Strom 15


Scrub Depth vs. Scrub Length

• Probes are planar

• Probes have same force

• Scrubs are longer/shorter

because of translation of stage

vs. card

Stage

Translation vs OT

June 2006 J. Strom 16


Scrub Depth vs Scrub Length

• Short Scrub

• 22u Long

• 0.6u Depth

•Long Scrub

• 30u long

• 0.9u Depth

June 2006 J. Strom 17


What is Punch-Through?

June 2006 J. Strom 18


waferWoRx - Spectral Scanning

June 2006 J. Strom 19


3-D Measurement - Punch Through

June 2006 J. Strom 20


3-D Measurement – Deep Scrub

Scrub Depth Consistently 0.9u with no punch-through

June 2006 J. Strom 21


Scrub Depth Repeatability

• Same Probe consistent in producing same scrub depth

• Same Probe consistently punches through to expose substrate

Scrub 1

Scrub 2

Scrub 1

Scrub 2

June 2006 J. Strom 22


Bump Analysis Capability

• Size and position of scrub

• Height of bump relative to the wafer surface

• Depth of scrub relative to height of the bump

• Planarity of the bumps

Unprobed

Off center

Scrub

Centered

Scrub

June 2006 J. Strom 23


Bump Analysis 3D / 2D

June 2006 J. Strom 24


Conclusion

• waferWoRx300 probe card measurements are

correlated to the scrubs

• Controlling scrub length is important to

controlling scrub depth

• Depth/Punch through is very repeatable for a

probe.

June 2006 J. Strom 25

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