Effects of Consumables on Nitride Erosion in STI CMP Process for Beyond 60nm Node Technology

摘要

As chip scale down, the issue of nitride erosion gets worse in STI CMP process. These issues can strongly influences the uniformity of isolation trench step height within a chip, which in turn degrades device performance. Hence, many efforts have been applied continuously to minimize the dishing and erosion in STI CMP process generation to generation, including adjustment of process parameters, introduction of dummy pattern, applying of reverse mask process and the evolution of consumables. However, the development of robust consumables including pad and slurry can directly and effectively minimize the issue of dishing and erosion. Hence, a good choice of robust consumables is very important for the improvement of erosion issue, particularly in the nanometer generation. In this report, the effect of consumable on nitride erosion in STI CMP for beyond 60nm node technology was investigated, which was correlated to active area (AA) pattern density, AA width and nitride loss. A practicable method combining the study of CMP test mask with simulation of raw data was applied for predicting and comparing the STI CMP performance of consumables, which CMP test mask was designed with nanometer the structure. The results indicated that acidic slurry can represent better performance of STI CMP on erosion against to over polish increasing, AA width scaling down and pattern density loosing. For comparison of pads, there is not apparent difference on erosion results, even more different properties between each other. At final, the effects of slurry and pads on erosion in SI CMP were also compared and discussed.