Yield improvement through implementation of edge scrub at post oxide dielectric CMP on 0.13 μm copper technology

In order to reduce defectivity and increase yield on 0.13 μm copper technologies, cost effective process and/or equipment improvements are needed. Potential improvements are often identified and evaluated by understanding the total wafer topography with specific emphasis on yield-limiting defects. One such process improvement was identified in the contact module, oxide CMP scrub process. Through defect analysis indicated that many of the particles detected after the contact TiN deposition stage were actually coming from residual slurry left on the wafer edge after the oxide CMP scrub process. Although not detected on the wafer surface immediately after the oxide CMP scrub process, these particles would relocate to the wafer surface after subsequent processing. To reduce residual slurry on the wafer edge, modifications to the post polish scrubbers were required. This paper describes the benefits and costs associated with this conversion.