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Product Briefing Outline: Applied Materials has introduced the ‘Applied Aera2’ Mask Inspection system that is designed to handle leading-edge photomask inspection and qualification tasks at the 45nm node and below, including double patterning. The Aera2 uses sophisticated aerial imaging technology to immediately see how the pattern on the mask will appear on the wafer. The system detects defects according to their impact on the wafer, filtering out the large number of non-printing defects that plague conventional mask inspection systems. Applied Materials claims that the Aera2 system addresses all mask shop inspection applications and provides more than twice the throughput of any competing system. 

Problem: Each new generation of photomasks incorporates increasingly sophisticated resolution enhancement techniques that reduce the correlation between the pattern on the mask and that on the printed wafer. This presents a challenge for traditional inspection systems since they can only produce an image of the mask itself. By emulating the optical system of 193nm lithography scanners and placing an image sensor in the wafer plane, the Aera2 system inspects the mask under the same optical conditions as when it is exposed in a stepper to provide “what you see is what you print” capability.

Solution: The Aera2 system’s aerial inspection technology also creates an entirely new set of capabilities that strengthen the link between the mask shop and lithography cell by ensuring the printability of a mask before delivery. The system features an optional ‘IntenCD’ application that leverages the aerial imaging data to create high-precision, high-density CD uniformity maps of an entire mask. This allows direct measurement of the complete mask to determine its contribution to wafer CD uniformity. These maps can reveal subtle manufacturing effects, helping mask makers to fine-tune the mask manufacturing process.

Applications: Sub-45nm photomask inspection and qualification, including extreme RET masks of all types.

Platform: When equipped with IntenCD for high-density, high-precision scanning of the entire reticle, Aera2 can generate maps of CD trends that could signal manufacturing process problems.  Global trends can be resolved to approximately 1nm. Mapping occurs concurrent with inspection and can be performed for a range of applications and simultaneously for multiple feature sizes.

Availability: April 2008 onwards.