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Edge Roll Off Measuring System Outline

To reduce failure in CMP or lithography process, it is important  to manage the profile of the silicon wafers edge. In recent years, edge roll off which represents the deviation from the plane in vicinity of the edge are gaining  high profiles　As an index to represent the edge roll-off, the parameter ROA(Roll Off Amount) has been proposed.　1)As shown below,  ROA  represents the difference between fitting line of the reference region that is set as X1~X2 from the edge of the wafer and the actual profile.  Larger the ROA the sag is occurring closer to the edger of the wafer　１）M. Kimura, et. al: Jpn. J. Appl. Phys. 38 (1999) pp38.

Principle

Grading Incidence Interferometer Method （LER series）

Our Edge Roll Off Measuring System uses Grading Incidence Interferometer Method.　Simultaneously the laser beam through prism is irradiated to front and rear surface of the wafer, while changing the distance of the wafer and the prism, it is possible to observe interference fringes using CCD camera.By analyzing the interference fringes to calculate the profile of the front  and rear surface of the wafer. And by the profile of the wafer the ROA and thickness will be measured .

Shack-Hartmann Method （SER Series）

Measuring Example

System Lineup

System Features

High-Throughput 

Front and Rear Simultaneous Measurement 

Non-Contact and Non-Destructive

Option 

OHT (Full-Auto) Compatible

Host Communications

Measurement services also available