Application for 3D surface mapping with high image resolution and measurement. Targeting product having high surface flatness or needed high precision measurement for 3D surface.

1. WhiteWhiteWhiteWhite LightLightLightLight InterferometryInterferometryInterferometryInterferometry
3D Profilometer

2. Theory background
• Interferometer uses the superposition principle to combine waves in a
way to extract information from the wave fronts.
• The position of the zero order interference fringe is independent of
wavelength
• A broadband “white light” source is used to illuminate the test and
reference surfaces
2
reference surfaces
• The reference beam is reflected by the reference mirror, while the
measurement beam is reflected or scattered from the test surface.
• Reconstruction of the surface based on the fringes snapped by the
camera

3. Intensity = A + B cos(φ) φ ∽ z 3D topographic
image of the
object surface
Light
Plane
Mirau microscope objective
3
Convergent
lens
Plane
reference
mirror
Reference
surface
z
Object surface
Interferences

4. • Step-height and roughness measurement
• White light interferometric profilometer
• Variable field of view due to revolver objectives
• High speed: full image recorded within seconds
Semilab Optical Profilometer
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• High speed: full image recorded within seconds
• Sub-micron lateral resolution
• Sub-nm height resolution
• CCD color camera
• Low sensitivity to vibrations
• Non-destructive

5. WLI
Camera resolution: 1024x1024 (2048 x 1088)
Pixel Size (on the sensor): 5.5µmx5.5µm
Acquisition speed: 500 fps (340 fps)
Measurement time (without motion): <1 sec
Depth resolution : < 0.1 nm
Repeatability: σ=0.3 - 6 nm depend on sample
Specification:
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Repeatability: σ=0.3 - 6 nm depend on sample
Multiple heads configuration available
Color Camera option
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Objective (3D) 50x 20x 10x
Maximum FOV (µm) 284x150 568x300 1136x600
Best optical resolution
(Rayleigh definition) (µm)
0.5 0.7 0.9
Field of views:

6. Application examples

7. Step-height measurement
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Critical dimension inspection of step-height
like profile

8. Flat Panel Transistor
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Critical dimension of flat panel transistor

9. Diamond cut solar cell wafer
1700 nm
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Solar cell wafer inspection of saw mark, surface roughness and features.
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10. Metal surface
3000 nm
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Metal surface inspection of screatches, surface roughness and features.
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11. Critical dimension of MEMS device
400 nm
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12. Optical surface with dust
1000 nm
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0

13. Recent WLI demo result: spacers height in FPD
structures
6000 nm
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14. Measurements Positions
Repeatibility measurement
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The Critical dimensions (Top and Bottom) are measured along the yellow axes
(nm)

15. 3D view of FPD structures
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16. Application examples
Surface roughness

17. 935575/4
200 nm
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18. Surface roughness and waviness
200 nm
RMS=4.797 nm
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RMS=36.273 nm

19. Surface roughness and waviness II.
RMS=4.797 nm
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RMS=36.273 nm

20. 9355755/128
250 nm
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0

21. Surface roughness and waviness
Bandpass
(0.027 to
2.75 um)
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Bandpass
(2.75 to
555 um)

22. RMS=9.433 nm
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RMS= 27.298 nm

23. 934344/4
250 nm
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0

24. Surface roughness and waviness
Bandpass
(0.027 to
2.75 um)
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Bandpass
(2.75 to
555 um)

25. RMS=7.762
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RMS= 36.554

26. 934344/128
400 nm
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0

27. Surface roughness and waviness
Bandpass
(0.027 to
2.75 um)
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Bandpass
(2.75 to
555 um)

28. RMS=28.122nm
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RMS= 50.088 nm

29. • Semilab is capable to deliver state of art 3d surface profiling metrology using white
light interferometry
• Best resolution available : high resolution camera can deliver data up to 2 Megapixels,
in less than 3s aquisition time
Conclusions
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in less than 3s aquisition time
• Semilab wli technology proved to work for various industrial applications in the flat
panel, solar cell and semiconductor area
• Excellent repeatability is proven to be in the range of few nm-s
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