Fraunhofer Institute for Electronic Nano Systems
Automated optical measurements, including statistical evaluations, are possible with the Confovis AOI WaferINSPECT 305. This is a confocal measurement system with objectives ranging from 2.5x to 100x magnification. Single wafers in sizes 4“, 6“ and 8“ can be loaded onto the automatic vacuum stage. In manual mode, individual chips can be characterized, as well. By capturing up to 20 optical layers per second, contrast evaluation is performed and the focal point is automatically determined. The system can be trained on the chip layouts/geometry of the wafers, enabling automated measurement tasks as well as 2D and 3D measurements. The measurement results can be output as a wafer map during automated measurements, allowing changes across the entire wafer to be quickly captured and evaluated. Examples include focus/dose variations or the investigation of inhomogeneities in etching processes. The height resolution is up to 3 nm according to VDI 2655, and a lateral resolution of up to 267 nm according to Rayleigh can be achieved. The Cognex software operating in the background, through AI-supported image recognition, enables not only the automatic measurement of geometric structures but also defect detection using the Golden Sample method. Overlay measurements for the control of successive lithography layers represent another application.
Highlights:
- Automated confocal measurement system
- 2D and 3D images as well as statistical evaluations across the entire wafer
- Overlay evaluations for quality control of successive lithography coatings
- AI-supported image recognition via software
- Defect detection using the Golden Sample method