Aerial image analysis based on UV reticle inspection

Sub-wavelength or Super-resolution lithography requires us to review defects after reticle inspection, be it at the mask house or at incoming inspection, with a completely new approach. With the advent of UV reticle inspection for the 0.25 micrometer and below regime, the lithography engineer in a wafer fab will ask for much more detailed classification and characterization of a reticle. While reticles are supposedly 100% defect free when they arrive at the customer, a detailed analysis of any potential printable defect is done by fab engineers as well as many mask engineers. A time consuming and QUALITATIVE analysis is often performed by AIMS metrology, however, no real QUANTITATIVE estimate of the 'printability' can be given. This paper discusses the solution of using fast aerial image analysis of defect information gathered by an advanced UV inspection system, with accurate printability prediction. The described methodology is on-line, real-time, and can be performed in an automatic mode with any inspection.