Development of CMP pad using an unpatterned surface inspection system

As the device continues to shrink, copper(Cu) chemical mechanical planarization (CMP) remains a challenging process for copper dual damascene processes. In the past, the standard blanket wafer defectivity detection system for CMP processes focused on particle or scratch count and characterization. However the standard methodology is no longer suitable for detecting anomalous process defects while technology nodes continue to scale down. Accessing defectivity information below standard thresholds can be achieved by wafer haze analysis. Wafer haze information can be used in addition to standard defectivity data to optimize CMP processes and characterize CMP defects. Haze analysis represents a powerful tool for capturing spatial signatures caused by CMP processes. [1, 2] This study shows how we applied KLA-Tencor's SURFmonitor with grid analysis to reveal defect signatures not apparent in the traditional darkfield defect map. This new method of using haze analysis to measure haze defects on Cu blanket wafers was used for characterization and development of CMP pads.