Optical Filters Used in Overlay Accuracy Inspection

Optical filters for overlay accuracy inspection are designed to transmit selected visible, ultraviolet, or near-infrared bands while reducing unwanted out-of-band light. In semiconductor metrology and photolithography, these filters enhance the optical contrast of alignment marks and structures between different wafer layers, enabling the measurement of layer-to-layer registration.

Applications:

• Semiconductor metrology for enhancing the contrast of alignment marks across multiple silicon wafer layers
• Photolithography process control for monitoring and calculating layer-to-layer overlay registration
• Defect inspection and Critical Dimension (CD) metrology in semiconductor fabrication