11 May 2009 Thorough characterization of an EUV mask
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Proceedings Volume 7379, Photomask and Next-Generation Lithography Mask Technology XVI; 73790J (2009); doi: 10.1117/12.824260
Event: Photomask and NGL Mask Technology XVI, 2009, Yokohama, Japan
We reported that we were successful in our 45nm technology node device demonstration in February 2008 and 22nm node technology node device patterning in February 2009 using ASML's Alpha Demo Tool (ADT).1, 2, 3 In order to insert extreme ultraviolet (EUV) lithography at the 15nm technology node and beyond, we have thoroughly characterized one EUV mask, a so-called NOVACD mask. In this paper, we report on three topics. The first topic is an analysis of line edge roughness (LER) using a mask Scanning Electron Microscope (SEM), an Atomic Force Microscope (AFM) and the Actinic Inspection Tool (AIT) to compare resist images printed with the ASML ADT. The results of the analysis show a good correlation between the mask AFM and the mask SEM measurements. However, the resist printing results for the isolated space patterns are slightly different. The cause of this discrepancy may be resist blur, image log slope and SEM image quality and so on. The second topic is an analysis of mask topography using an AFM and relative reflectivity of mirror and absorber surface using the AIT. The AFM data show 6 and 7 angstrom rms roughness for mirror and absorber, respectively. The reflectivity measurements show that the mirror reflects EUV light about 20 times higher than absorber. The last topic is an analysis of a 32nm technology node SRAM cell which includes a comparison of mask SEM image, AIT image, resist image and simulation results. The ADT images of the SRAM pattern were of high quality even though the mask patters were not corrected for OPC or any EUV-specific effects. Image simulation results were in good agreement with the printing results.
© (2009) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Hiroyuki Mizuno, Gregory McIntyre, Chiew-seng Koay, Martin Burkhardt, Long He, John Hartley, Corbet Johnson, Sudharshanan Raghunathan, Kenneth Goldberg, Iacopo Mochi, Bruno La Fontaine, Obert Wood, "Thorough characterization of an EUV mask", Proc. SPIE 7379, Photomask and Next-Generation Lithography Mask Technology XVI, 73790J (11 May 2009); doi: 10.1117/12.824260; https://doi.org/10.1117/12.824260

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