Abstract
A big yield drop has been observed during the automatic inspection (AOI) after the saw stage. A step by step AOI inspection check and defect review is made to see which step made a big yield drop and which kind of defect contributed most to the yield drop. Scanning electron microscope (SEM) and energy dispersive spectrometer (EDS) analysis showed the shape and chemical element of the particle. From the EDS result, particles can be separated into two categories. One was the inorganic related materials, mainly including silicon (Si) element, which came from the saw stage. A design of experiment (DOE) is used to find some reasonable saw relative parameter and optimize it in order to remove the particle from the saw stage. But the quantity of this kind of particle was small. Yield was only improved by less than 5%. Our main effort was to remove another kind of particle which was organic related materials, mainly including carbon (C) and oxygen (O) element. This kind of particle was from tape residue. In order to remove the tape residual, one step was added before the saw stage. Almost all of the tape residual was removed. Finally, the final yield was improved by more than 15%.
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