Wafer Near-Edge Roundness Control for Smooth Bevel Transitions

The patent replaces conventional mechanical contact-based roundness measurement systems with a non-contact optical scanning system. The optical scanner uses light to capture wafer edge profiles and calculate NER parameters, eliminating mechanical contact that could damage the wafer or introduce measurement errors in the delicate near edge region.

The patent introduces new measurement parameters (NER radius and theta angle) that specifically characterize the near edge region transition geometry. These parameters enable precise quantification and control of the transition smoothness from top surface to bevel, allowing optimization of this critical region that was previously difficult to measure and control.

The patent performs NER parameter measurement and tool anomaly detection early in the manufacturing process, before wafers undergo subsequent processing steps. This preliminary detection allows for early correction of tool issues, preventing defect propagation through the manufacturing process and reducing overall processing time by avoiding rework later.

The patent implements a feedback mechanism where NER parameter measurements are continuously monitored and used to detect tool anomalies. When deviations are detected, the system provides feedback to adjust tool parameters or alert operators, enabling real-time correction that maintains high device yield without requiring complete process shutdowns.