Automated residual metal inspection

Residual metal inspection is an integral part of CMP manufacturing processes. This can be accomplished by adapting the existing YE inspection tools or microscopes. The use of Front Opening Unified Pod (FOUP) to house the wafers in 300 mm manufacturing offers unique challenges for wafer handling which necessitates the use of automated inspection procedures. These automated inspection procedures must not impede the flow of production material while achieving 100% inspection, and also have increased reliability compared to the existing inspection technologies. Ideally, these inspection procedures should be integrated into a feedback loop for further processing control. In this study, an existing particle monitoring technology for both bare and patterned wafers has been adapted for residual metal inspection. This is a new and unique application for post-metal CMP residue metal detection, which replaces the microscope visual inspection process. This technique uses a previously scanned 'golden wafer' to create the inspection recipe for a given pattern density and metal thickness, which is used to inspect other similarly processed product. This technique can be integrated to a CMP process tool, which can lead to significant reduction in cycle time and improved inspection efficiency.