Post Titanium Nitride (TiN) Sputter Deposition Scrubber Clean

摘要

Controlling particle contamination in device manufacturing is becoming increasingly important to reduce defect density and improve device performance and yield. In addition, trace metal levels need to be drastically decreased in order to maintain device reliability according to device feature size reduction. The application of wet chemical brush cleaning at the back-end of integrated circuit fabrication (BEOL), where the wafers are due to the already performed manufacturing steps most valuable, has been reluctantly introduced due to the vulnerability of the layers used in BEOL steps. Titanium Nitride (TiN) has long been used in semiconductor manufacturing, predominantly as a barrier layer at the metal silicon contact to prevent cross diffusion and as an antireflective coating (ARC) on aluminium to extend lithographic structuring capability and reduce light scattering related defects. Because of increasing complexity of device, architecture the number of TiN layers (particularly AR layers) needed in a complete process flow is also increasing. Magnetron Sputtering is the most commonly used method for depositing ARCs, particularly for TiN. However due to both the inherent properties of TiN and the process, some particle generation is always observed and seen by many as an unwelcome but necessary trade off against cost and performance. The resulting particles are conductive and depending on size can cause severe yield loss due to creation of shorts between metal lines and shadowing during metal structure generation (etching). In this article, we show the beneficial effects of implementing a post TiN ARC scrubber process and its impact on the defect density, surface roughness, reflectivity, metal contamination as well as on reducing defect density.