This paper examines the effects of mask printability of various OPC defect types on a MoSi APSM mask using an MSM-100 AIMS tool operating at 248nm as a printability prediction tool. Printability analysis will be used to address differences in intensity, image capture wavelength, defocus, defect size, type, and placement on two substrate materials. Defect correlation to photomask CD error, aerial image intensity error, and MEEF on high-end KrF photomasks will also be studied.

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The photomask is a critical element in the lithographic image transfer process from the drawn layout to the final structures on the wafer. The non-linearity of the imaging process and the related MEEF impose a tight control requirement on the photomask critical dimensions.Critical dimensions can be measured in aerial images with hardware emulation. This is a more recent complement to the standard scanning electron microscope measurement of wafers and photomasks. Aerial image measurement includes non-linear, 3-dimensional, and materials effects on imaging that cannot be observed directly by SEM measurement of the mask. Aerial image measurement excludes the processing effects of printing and etching on the wafer. This presents a unique contribution to the difficult process control and modeling tasks in mask making.In the past, aerial image measurements have been used mainly to characterize the printability of mask repair sites. Development of photomask CD characterization with the AIMS™ tool was motivated by the benefit of MEEF sensitivity and the shorter feedback loop compared to wafer exposures. This paper describes a new application that includes: an improved interface for the selection of meaningful locations using the photomask and design layout data with the Calibre™ Metrology Interface, an automated recipe generation process, an automated measurement process, and automated analysis and result reporting on a Carl Zeiss AIMS™ system.

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Using AIMS™ to qualify repairs of defects on photomasks is an industry standard. AIMS™ images match the lithographic imaging performance without the need for wafer prints. Utilization of this capability by photomask manufacturers has risen due to the increased complexity of layouts incorporating RET and phase shift technologies. Tighter specifications by end-users have pushed AIMS™ analysis to now include CD performance results in addition to the traditional intensity performance results.Discussed is a new Repair Verification system for automated analysis of AIMS™ images. Newly designed user interfaces and algorithms guide users through predefined analysis routines as to minimize errors. There are two main routines discussed, one allowing multiple reference sites along with a test/defect site within a single image of repeating features. The second routine compares a test/defect measurement image with a reference measurement image. Three evaluation methods possible with the compared images are discussed in the context of providing thorough analysis capability.This paper highlights new functionality for AIMS™ analysis. Using structured analysis processes and innovative analysis tools leads to a highly efficient and more reliable result reporting of repair verification analysis.