Investigation of bump defects formed in back end of line for 28 nm technological node

Abstract

In order to quickly ramp up and maintain good yield, it was very important that the bump defects as the killer for 28 nm technological node were accurately detected, and the quantities of the bump defects rapidly decreased by the adjusting processes. The main purpose of this paper was to investigate the performance of the bump defects in the back end of line for 28 nm technology and detect the seeds of the forming bump defect. Firstly, the bump defects were scanned by the optical examination instrument. Subsequently, the scanned defect map was transferred into scanning electron microscopy reviewing system to observe the types and sizes of the bump defects. For finding the seed of forming the bump defect, the defects were cut from the wafer using a focused ion beam, and then a transmission electron microscope was used for observing interface to identify the location of the seed of forming the bump defect. Results showed that the bump defect originated from the interface between metal (after chemical mechanical polish) and dielectric cap layer. In addition, an in‐depth study of the formation of the bump defect was carried out using the different film stacks. Copyright © 2016 John Wiley & Sons, Ltd.