ESD damages reticles in semiconductor manufacturing

1. 1
DuPont Photomasks, Inc.
ESD and Reticle Damage
K. C. Wang, MBA, MS Ch.E.
Director, New Ventures Development
October 19, 2000
International SEMATECH
Electrostatic Discharge Impact
and Control Workshop

2. 2
DuPont Photomasks, Inc.
Disclaimer
The information provided in the SEMATECH ESD
workshop and publications presented on October
19 and 20, 2000 regarding DuPont Photomasks,
Inc.’s CanaryTM technology is for informational
purposes only. CanaryTM is a registered trademark
and is subject to patent and trade secret
protection in accordance with United States and
foreign law and regulations. The use, copying,
transfer and publication of this proprietary
technology is strictly prohibited by law.

3. 3
DuPont Photomasks, Inc.
Why Photo Areas?
nAdvanced design rule
nProcess complexity
nDefect induced and sensitive
nIncreasing cost of reticles
nReticle quality impacting
wafer yield significantly

4. 4
DuPont Photomasks, Inc.
The Approach of a Charged Object
Repeated Sparking!

5. 5
DuPont Photomasks, Inc.
A Reticle in a Pod
Operator’s fingers
When the operator takes or releases the pod,
it becomes tribo-electrically charged at the finger sites.

6. 6
DuPont Photomasks, Inc.
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Bringing a Reticle Near a Charged
Surface is Hazardous to the Reticle

7. 7
DuPont Photomasks, Inc.
Compare a 5 µm Gap (then) and a 1 µm Gap (now)
Voltage Thresholdthen= 5x Voltage Threshold now
Energy Deposit then= 25x Energy Deposit now
Chrome Temperature then= 25x Chrome Temperature now
Vaporized Chrome Melted Chrome
1 or 2 rare sparks 100 frequently occurring sparks
Conclusion - modern reticle damage is cumulative
- past generation damage was catastrophic
Wait long enough and your reticle lines will melt!

8. 8
DuPont Photomasks, Inc.
ESD Learning
n Reticle damage is caused by
nearby charged objects
n In the past it was catastrophic and
rare
n Now it is very common but not a
single shot event
n Modern reticles accumulate ESD
damage over time

9. 9
DuPont Photomasks, Inc.
The Canary Reticle
Varying gap size

10. 10
DuPont Photomasks, Inc.
CANARY - Sensitivity

11. 11
DuPont Photomasks, Inc.
Canary ESD Damages
A1 A17 A20 A22 A23 A25

12. 12
DuPont Photomasks, Inc.
Evolution of ESD Damage

13. 13
DuPont Photomasks, Inc.
Canary Applications in
Semiconductor Fabs
n Customized Canary design
♦ alignment mark
♦ bar code
♦ design rule: gap, linewidth
n Wafer fabrication environment
characterization and safeguard
♦ ESD defect printability
♦ reticle stocker room
♦ reticle pod
♦ reticle handling path and procedure
♦ lithography & inspection equipment

14. 14
DuPont Photomasks, Inc.
Canary Diagnosis and Solution Flow
Initial
Assessment
EMI/RFI
Study
Canary
Run
Report
Recommend
Solution
Implement
Solution
Canary
Confirmation
Run
Routine
Compliance
Certification

15. 15
DuPont Photomasks, Inc.
Possible Solutions
n Change of process
n Redesigns of procedures and flow
n ESD awareness training
n ESD protection
n Remote on-line monitoring
n Materials changes
n Equipment grounding issues
n ESD control program improvements
♦ Periodic Canary runs
♦ ESD audits to 20.20 spec
♦ E78 exit charge tests

16. 16
DuPont Photomasks, Inc.
Canary Applications in
Semiconductor Equipment
nMethodology determining level of
E78 compliance required
nCanary test method required in
procurement spec
nAcceptance test item

17. 17
DuPont Photomasks, Inc.
Canary Development Status
nAlpha site tests complete
nAdvanced fab beta site tests complete
nProduction customer orders start
nCurrent service capacity is limited

18. 18
DuPont Photomasks, Inc.
Summary
Benefits to Semiconductor Industry
nHolistic ESD control (peace of mind)
nSignificant cost savings and productivity
improvements (lowest cost of ownership)
nMarketing competitive advantage
nShared problem solving accountability
and teamwork (users and suppliers)