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20 May 2004 Modeling LEEPL mask fabrication processes
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The challenges in fabricating next-generation lithography (NGL) masks are distinct from those encountered in optical technology. The masks for electron proximity lithography, as well as those for ion and electron projection, use freestanding membranes incorporating layers that are different from the traditional chrome-on-glass photomask blanks. As a promising NGL technology, low-energy electron-beam proximity-projection lithography (LEEPL) will be subject to strict error budgets, requiring high pattern placement accuracy. Meeting these stringent conditions will necessitate an optimization of the design parameters involved in the mask fabrication process. Consequently, comprehensive simulations can be used to characterize the sources of the mechanical distortions induced in LEEPL masks during fabrication, pattern transfer, and mounting. For this purpose, finite element (FE) structural models have been developed to identify the response of the LEEPL mask during fabrication and chucking. Membrane prestress, which is used as input in the FE models, was measured on a 200-mm test mask and found to low in magnitude with excellent cross-mask uniformity. The numerical models were also validated both analytically and experimentally considering intrinsic and extrinsic loading of the mask. Finally, simulations were performed to predict the response of the LEEPL mask during electrostatic chucking. FE results indicate that the mask structure is sufficiently stiff to remain relatively flat under gravitational loadings. The results illustrate that mechanical modeling and simulation can facilitate the timely and cost-effective implementation of the LEEPL technology.
© (2004) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Xabier Azkorra, Andrew R. Mikkelson, Roxann L. Engelstad, Edward G. Lovell, Jaehyuk Chang, Jaewoong Sohn, Madhura Nataraju, and Hideyuki Eguchi "Modeling LEEPL mask fabrication processes", Proc. SPIE 5374, Emerging Lithographic Technologies VIII, (20 May 2004);


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