The Defect Reduction of Via Opens by the Integration of Inter-Metal-Dielectric Film, Metal Hard Mask, and All-in-One Etch Processes

Abstract

This research aims at the pattern failure defects by the backend all-in-one (AIO) etching process during a recent technology development in a 12-inch FAB. The AIO etch directly defines the shape of both trench and via, however, those previous process steps involving the deposition of inter-layer-dielectric film, metal hard mask and the wet clean would contribute to the AIO etch performance and even cause pattern defects. The investigation elucidates the count of pattern failure defects strong correlates with the life time of ST250 which was used to remove polymer post metal hard etch process. The experiments shows that to extend ST250 rise time and add a scrubber process step can achieve a comparable defect performance with the old acid which run time > 50hrs. Eventually, the additional scrubber process was added to reduce defect counts and gained end-of-the-line 4% yield.