Introduce Projection Alignment as the Fix

# Introduce Projection (Non-Contact) Alignment as the Fix

The fix that defined this generation of lithography was to stop touching the mask to the wafer at all, and instead project the mask's pattern onto the wafer through an optical imaging system held at a working distance.

Light passed through the mask, through an optical system, and onto the resist-coated wafer below, with the mask and wafer never making physical contact during exposure.

This single change, projection rather than contact, eliminated the scratch-and-transfer defect mechanism at its root, because there was no longer a contact event for a particle to exploit.

PROJECTION VS CONTACTContact methodmask pressed directly onto the waferProjection methodmask imaged onto the wafer through an optical systemKey differenceno physical contact event during exposure

Diagram above: projection vs contact.

WHY THIS SOLVED THE DEFECT PROBLEMRoot cause removedno contact event, no scratch-and-transfer pathMask protectionthe mask pattern is imaged, never touched to the waferResultthe compounding defect mechanism simply cannot occur

Diagram above: why this solved the defect problem.

Take introduce projection alignment as the fix further

Ask the copilot about this term, or have our engineers assess it against your process.

Ask CFSGPT about this → Request a technical assessment → Open the CFS app