Wafer Inspection System

The Wafer Inspection System simultaneously acquires multiple illumination conditions in a single scan. It detects cosmetic defects on silicon wafers invisible to the human eye, such as sub-pixel sized scratches, cracks, and stains. The system consists of Chromasens allPIXA evo 15k CxP4 mono cameras, Myutron XLS05 lenses, an XCL4 LED controller, and Corona II lighting with coaxial light modules for dark field and bright field illumination. The allPIXA evo 15k CxP4 mono camera is equipped with a trilinear CMOS line scan sensor delivering maximum line length of 15,360 pixels (15K). Leveraging the CoaXPress (CXP) interface enables the camera to achieve full resolution of 15K at line rates up to 68.4 kHz.

The allPIXA evo 15k CxP4 camera can trigger up to four different flash controller channels synchronized to its line acquisition using a multi-channel LED flash. By integrating both Corona II bright field and dark field illuminations, the system acquires multiple lighting conditions in one scan of the wafer. All types of non-directional scratches on the wafer can be captured with dark field illumination by getting high light intensity into deep grooves. Conversely, with bright field illumination, the stains on the wafers are more apparent by diffuse light. Bright field RGB LEDs inspect wafer coatings via interference effects.