Semiconductor manufacturers are seeking for fast and precise measurements of the wafer edge. Especially when wafers are getting thinner, the more likely they break. This breakage could be caused by insensitive handling or originate from broken and chipped wafer edges. A novel contactless screening laser Wafer Edge Screener micrometer, called Wafer Edge Screener, which inspects wafer edges during common pre-alignment processes, can profile the wafer edge thickness and quantify upper and lower edge defects. The proposed measurement setup relies on multiple exposures of the wafer edge onto a light sensitive detector using point light sources, such as Laserdiodes. By evaluating the projected edge position on the light sensitive detector, the X/Y position of the wafer edge can be determined. The overall measurement accuracy is strongly influenced by the edge prediction techniques used, the light source, and furthermore some other parasitic effects. To achieve subpixel accuracy for determining the projected edge position on the detector, effects regarding laser speckles were investigated. In the test setup, a thin edge was continuously moved in parallel to the sensor, which results in a continuous movement of the projected diffraction pattern and its contained features on the sensor. By tracking these features, irregularities of their movement caused by temperature dependent Laser speckle can be investigated.
|Publication status||Published - 22 Nov 2017|
|Event||3rd International Conference on Integrated Functional Nano Systems - KFU Graz, Graz, Austria|
Duration: 22 Nov 2017 → 24 Nov 2017
|Conference||3rd International Conference on Integrated Functional Nano Systems|
|Abbreviated title||nanoFis 2017|
|Period||22/11/17 → 24/11/17|
- Laser speckle;