Formation mechanism of scratches on ILD CMP

ILD CMP 공정중 발생하는 Scratch 발생기구에 관한 연구

ILD CMP process has been well accepted for the planarization of the dielectric oxide film and becomes a critical process in ULSI manufacturing due to the rapid shrinkage of the design rule for the device. In total manufacturing process steps for a device, the proportion of ILD CMP process has been gradually increased. Ever since ILD CMP has been introduced, the scratches have been a major defects on polished surfaces which cause the electrical shorts between vias or metal lines [1,2]. It was reported that micro-scratches are caused by large, irregularly shaped particles during CMP process. Therefore, most of the CMP users have used < 5 m POU filter to remove and reduce the scratch source from the slurry. However, the scratch has always been the biggest concern in ILD polishing whatever preventive actions are taken. Silica and ceria slurries are widely used for ILD CMP process. There are not much differences in generated scratches and their formation mechanism. In this study, the scratches were investigated as a function of polishing conditions with possible explanation on formation mechanism in ILD CMP.