DFM software for photomask production and qualification of its accuracy and functionality

Abstract

An automatic system that combines actions in both the image domain as well as in the layout-database domain for accurate mask-defect analysis and application of design criticality will be presented. In this paper we will emphasize the qualification and calibration of the system and its various pieces of functionality with the use of programmed defect masks and low-voltage mask CD-SEM measurement data. Results on 1D and 2D programmed defects of various natures are reported in dense layout as well as in real memory design layout. The results show that the system can accurately extract mask CD-errors and defect sizes at a resolution far below that of the pixel-size of state-of-the-art mask-defect inspection tools at nanometer resolution.We will further demonstrate that mask-defect-inspection data can contain optical anomalies when defect or residual feature sizes are smaller than the inspection wavelength. Mask inspection images then no longer show the real defect. These anomalies can be analyzed with the system using advanced image actions.Finally, we will demonstrate the capability to calculate the effects that defects have on final wafer printability even without the need for input layout. Hence, model-based defect properties can be combined with rule-based defect properties as well as multi-layer, design-based criticality-region properties for utter flexibility in defect disposition capability.