Abstract: A system and method for performing optical inspection of structures on the surface of a semiconductor wafer. The wafer surface is illuminated with a polychromatic light source. A multiple-charged couple-device (CCD) camera is positioned to capture light diffracted by the structures on the wafer surface at the first order of diffraction. The captured light is then separated into a plurality of component wavelengths which are directed onto the CCDs. A digital filter creates a plurality of digitized diffractive images of the wafer surface at different component wavelengths. The diffractive images may be integrated and analyzed to detect defects in the structures, or may be, analyzed individually. An image at a particular wavelength may be selected and analyzed by using the known grating pitch of the structures to calculate the wavelength.

Abstract: A system and method of optically inspecting a structure on a surface of a production object which is supported on a moving inspection platform. The method reliably traces structure edges and stores structure and structure island characteristics. The system uses a camera and a light or energy source to sharply delineate the structure edges. A sequence of images of the object and the structure are captured, and the structure is detected in each image. The structure is then symbolically decomposed into primitives, and a histogram is produced for each image identifying the slope and length of each edge of the structure. The histograms are compared in each image, and are aligned to eliminate differences due to wobble of the inspection platform or differences in magnification. A production structure grammar is then produced from the aligned images. The production structure grammar is compared to a reference structure grammar generated from a defect-free object.

Abstract: A system and method of optically inspecting structures on the surface of an object, such as a semiconductor wafer. A platform is used to support the object under examination, and provided thereat are lights or other energy sources for illumination disposed at a selected angular orientation. Optimum illumination is achieved by orienting two opposing lateral energy sources to direct energy along the surface of the object at a very low angle, and using them in conjunction with a coaxial light source that emits energy, which is directed downward toward the surface. Energy reflected back from the surface is captured as an image by a suitable device such as a CCD camera. The lighting may be controlled by an attached computer, which can also be used to process and store the captured image and analyze it to detect and catagorize defects in the object being inspected.

Abstract: An apparatus, system, and method of optically inspecting printed circuit boards (PCBs) for defects, that reliably determines the dimensions of components including those having the same color as the background, and which can detect components which are missing, misoriented, misaligned, or not properly seated. The apparatus uses a camera and a coherent primary light source mounted at an angle away from the vertical so as to produce sharply defined PCB component shadows on the top surface of the PCB. An image of the PCB is captured, the shadow edges are symbolically decomposed into primitives from which gradients are produced, and then compared to a previously captured gradient of a defect-free PCB. Differences in the two image gradients, if any, are used to identify missing, misaligned, misoriented, and improperly seated components, and to detect foreign objects and other PCB defects.