Application of image-processing software to characterize the photomask key parameters for future technologies

Abstract

The intent of photomask metrology has always been to understand the relationship between the features on the photomask and the design data. This desire has been actuated by the necessity to close the loop between the photomask process steps and the wafer lithography. As the Si technology approaches 0.25 micron and beyond, and the employment of resolution enhancement techniques (OPC and phase shifting mask) to extend the capability of optical lithography, both the photomask critical dimension control and pattern fidelity become important and challenging.Describing the features accurately on the photomask is critical to ensure the quality of photomasks.In this paper, the image processing software is examined for measuring and characterizing key photomask parameters, such as edge roughness, edge defects, isolated defects, corner rounding, and contacts. With this image processing software, the effect of mask processing on those key mask parameters, and the impact of those key parameters on defect printability were characterized. Thus, the application of Image Processing Software will contribute immensely to photomask metrology.