FLATSCAN

 

Optical non contact surface profilometer for measurement

of surface curvature (radius, form) and thin film stress (waferstress)

 

 

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Optical measuring principle for surface form measurement

FLATSCAN serves for the contactless measurement of flatness, waviness, mean radius and thin film stress of all kinds of reflecting surfaces like silicon wafers, mirrors, x-ray-mirrors (goebel-mirrors), metal surfaces or polished polymers. The optical measurement principle ensures a high accuracy. It is based on the measurement of the reflection angle of a perpendicular incident laser beam along a line with constant step width. The surface form can be calculated exactly from the change of the reflection angle from between the measuring points. For some applications the reflection angle itself is interesting. Therefore the software offers additionally this measuring option.

For applications in semiconductor technology the thin film stress in coatings can be calculated by the measured radii before and after coating.

 

 

Large measuring field

A special feature of the used measuring principle is its indpendence from the measuring field.

Therefore the standard measuring field diameter of 200mm can be increased nearly arbitrarily without decrease of accuracy.

 

High measuring accuracy

FLATSCAN is featured by a high measuring accuracy. The resolution of the measuring systems is 0,1 arcsec. The surface form reproducibility amounts to 100nm.

 

Large measuring range and working distance

The measuring range is the maximum arrow height (or the smallest measurable radius of curvature), which can be measured during one scan. FLATSCAN is featured by an extremely large measuring range ,which cannot achieved with competitive measuring methods like fringe interferometers.

FLATSCAN is therefore suitable for the measurement of surfaces with strong curvature like goebel-mirrors, silicon wafers or others. The used optical measuring principle works independent from the working distance and ensures a high working distance, thus no danger for damaging the specimen.

 

Optional 2D- or 3D-measurement

Optional, according device type, single line scans or complete 3D scans can be accomplished.

The 3D-scans are assembled from numerous single line scans with automatic specimen positioning.

The software offers all stae of the art usual possibilities for graphical and numerical representation of measuring results like 3D-representation, sectional views and measuring protocols.

 

Software modul for computation of thin film stress

For use in semiconductor technology and for all applications, where surface modifications (like coating or removal of coatings) are accomplished, the software is equipped with a modul for computation of the thin film stress by the Fowkes theory. By that means FLATSCAN allows the fast and easy measurement of thin film stress.

The thin film stress is computed from the mean radius of curvature before and after the coating process.

 

 

Technical Parameters

 

Parameter

FLATSCAN

Reproducibility surface curvature (P-V)

≤ 100nm**

Resolution of optical measuring system

0,1 arcsec

Accuracy of optical measuring system

1 arcsec

Measuring speed

10mm...30mm / sec

Measuring field

Standard: Æ 200mm *

(large fields possible without problems

Specimen thickness

not limited

Minimum Radius of curvature and according arrow height in dependence of scan length

         200mm:        R=18 m        290 µm

         300mm:        R=25m         435µm

         500mm:        R=43m         725µm

free working distance

not limited

Measuring wavelength

Standard: 670nm*

Automatic measuring sequence

yes

  

* standard equipment, can be adapted to othet demands

 

** Standard deviation at 50 measurements of the same scan with a standard specimen under standard measuring conditions

 

 


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