AIMS (Aerial Image Measurement System) is a dedicated metrology tool that emulates the optical conditions of a lithographic scanner to image mask features — reproducing the exact wavelength, NA, illumination conditions, and partial coherence of the production scanner to predict how mask patterns and defects will print on the wafer.

AIMS Capabilities

• Emulation: Matches scanner illumination (wavelength, NA, sigma, polarization) — images the mask as the scanner would.
• Through-Focus: Acquires aerial images at multiple defocus positions — determines printability across the process window.
• CD Measurement: Extracts CD from the aerial image — predicts wafer-level CD from the mask.
• Defect Review: After automatic inspection identifies suspect defects, AIMS determines their printability.

Why It Matters

• Defect Disposition: AIMS is the final arbiter for mask defect printability — "will this defect print or not?"
• Repair Verification: After mask repair, AIMS confirms the repair was successful — verify printability, not just physical restoration.
• Cost: AIMS review is essential but expensive — tools cost $10M+ and measurement is time-consuming.

AIMS is the scanner simulation microscope — emulating lithographic imaging conditions to predict exactly how mask features will appear on the wafer.