An Optical Inspection System Development for Defects on Multi-surfaces of Chips

We proposed a new architecture with multiple pick and place heads to suck inspected chips and to be moved synchronously for acquiring the images of different surfaces on different chips at their corresponding acquisition stations. The computation loading of defect inspection for each chip also can be distributed because of sequential image acquisition. Considering the different computing loading of 6 surfaces of a chip, image acquisition for the front and back sides of chips is allocated at the first and second stations, and then 4 edge sides of chips. The modification and calibration of position and orientation for each opto-mechanical device will be simpler and easier when the characteristics of inspected chips changed. Thus system can accomplish the inspection for 6 surfaces of each chip and determine its quality in real-time before that chip is put onto target wafer. Developed inspection system has advantages and contributions of real-time inspection with high throughput during chip sorting process, and easily adjustment and calibration for all opto-mechanical devices to inspectdifferent types of chips. The first phase of development was accomplished for an AOI system to inspect defects on 5 surfaces of chips. System has been integrated in customer’s chip sorter for testing. The inspecting accuracy for chip backside is better than 95%.