Chip sorter is one of packaging facilities in chip manufactory. Defects will occur for a few of chips during
manufacturing processes. If the size of chip defects is larger than a criterion of impacting chip quality, these flawed
chips have to be detected and removed. Defects inspection system is usually developed with frame CCD imagers.
There're some drawbacks for this system, such as mechanism of pause type for image acquisition, complicated
acquisition control, easy damage for moving components, etc. And acquired images per chip have to be processed in
radiometry and geometry and then pieced together before inspection. These processes impact the accuracy and
efficiency of defects inspection. So approaches of image acquisition system and its opto-mechanical module will be
critical for inspection system.
In this article, design and characterization of a new image acquisition system and its opto-mechanical module are
presented. Defects with size of greater than 15μm have to be inspected. Inspection performance shall be greater than
0.6 m/sec. Thus image acquisition system shall have the characteristics of having (1) the resolution of 5μm and 10μm
for optical lens and linear CCD imager respectively; (2) the lens magnification of 2; (3) the line rate of greater than 120
kHz for imager output. The design of structure and outlines for new system and module are also described in this work.
Proposed system has advantages of such as transporting chips in constant speed to acquire images, using one image only
per chip for inspection, no image-mosaic process, simplifying the control of image acquisition. And the inspection
efficiency and accuracy will be substantially improved.