Macro Inspection concept based on Flatbed scanner

1. OCR CHIPPED WAFER DETECTION(based CIS)
By LV Tailoring Software

2. OCR CHIPPED WAFER DETECTION
•Significant issues related to the existence of chipped surfaces on outer periphery of the production wafers as result of improper wafer handling. Chipped surfaces are exposed to thermal and mechanical impact subsequently leading to breakage of the silicon plate.
•Significant impact to tool availability as result of the internal silicon plate breakage –long clean up and recovery time.
•Expected impact to tool quality –remaining breakage particle effect.
•No existing monitor for chipped wafers in existence (internal or external vendors as well.)
12/13/2014

3. OCR CHIPPED WAFER DETECTION
•Task -Creation prototype of the in line monitor based OCR ( tool and operation wise) to detect chipped surfaces on outer perimeter of the wafer plate.
•Basic requirements :
a.Usage OCR as equipment base for inline detector.
b.Show possibility to detect chipped surfaces based on conventional image acquisition and processing.
c.Development of basic strategy, architecture and algorithms for such operation
d.Further evaluation of possibilities.
12/13/2014

4. CAMERA BASED CHIPPED WAFER DETECTOR
12/13/2014

5. CAMERA BASED OPERATION IMPACT
Impact on OCR operation:
•Extension of OCR operation 40-50 sec to 2 min.
•Layout impact (x 2,5 space).
•Illumination issues
•Ergonomic impact
•Computation impact for front and back (x2 PC x2 Camera etc…)
•Results inconsistency ( cassette previous position dependence – notch placement) Placementof cassette
Regular
OCR rotation
operation
Regular
OCR reading
operation
Camera
snaps-up
to 400 frames
Save snaps
to HD
Image
processing
results
12
0
62
120
Regular
OCR rotation
operation (2)
24

6. SCANNER CIS BASED CHIPPED WAFER DETECTOR
12/13/2014

7. SCAN CIS BASED OPERATION IMPACT
Impact on OCR operation:
•Extension of OCR operation 40-50 sec to 70 sec.
•Layout impact (+20%)
Placement
of cassette
Regular
notch
rotation
Regular
Post alignment
rotation
Waiting
CCS Scan
Image
processing
results
12
0
62
120
Regular
OCR rotation
operation
24
12/13/2014

8. OCR BASED CHIPPED WAFER DETECTION
•Task -Creation prototype of the in line monitor based OCR ( tool and operation wise) to detect chipped surfaces on outer perimeter of the wafer plate.
•Basic requirements :
A.Usage OCR as equipment base for inline detector.
B.Show possibility to detect chipped surfaces based on conventional image acquisition and processing.
C.Development of basic strategy, architecture and algorithms for such operation.
12/13/2014

9. 12/13/2014
OCR BASED CHIPPED WAFER DETECTION
Comparative results for CIS based detector
Testing
SCAN CCSBASED
True detections front and back
Y
Average true detection
92%
Average false detection
10%
MaximumResolution
150um
EffectiveResolution
220um
As result of the scanning operation at 300x300 dpi resulted image ~3000x200 pixels
processed for inconsistencies look up using basic grey morphology algorithms.

10. Comparative results for Camera and CIS based detectors
Testing
CAMERA BASED
SCAN CCSBASED
True detections front
50%
N/A
True detections back
83%
N/A
Average true detection
66.5%
92%
False alarm front
15%
N/A
False alarm back
20%
N/A
Average false detection
17.5%
10%
MaximumResolution
300um
150um
EffectiveResolution
500um
200um

11. Back up
12/13/2014

12. CIS SCANNNER ON OCR TOOL
Full assembly with OCR
Assembly without OCR
SCAN CIS
12/13/2014
WAFERS

13. SCAN CCS BASED CIS DETECTABILITY
Defect detected by
OCR CIS
Estimated size 400um
Defect detected by OCR CIS
Estimated size 300um
12/13/2014