Silicon thinning and polishing on packaged devices

Sample preparation with the ChipUnzip tool makes it possible to insure the functionality of packaged devices after opening. For debug and failure anal ysis, the silicon substrate needs to be thinned down to less than 50 micron s while maintaining the functionality of the packaged device. This as prove d to be very difficult on large dies. As we will present in this paper it i s difficult to obtain a uniform silicon thickness after thinning due to som e bending issues. Finally, we will present our fine polishing results, whic h represent a key issue for backside failure analysis. (C) 2001 Elsevier Sc ience Ltd. All rights reserved.