1 August 2017 Reducing extreme ultraviolet mask three-dimensional effects by alternative metal absorbers
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J. of Micro/Nanolithography, MEMS, and MOEMS, 16(4), 041002 (2017). doi:10.1117/1.JMM.16.4.041002
Over the recent years, extreme ultraviolet (EUV) lithography has demonstrated the patterning of ever-shrinking feature sizes (enabling the N7 technology node and below), whereas the EUV mask has remained unaltered, using a 70-nm tantalum (Ta)-based absorber. This has led to experimentally observed mask three-dimensional (M3D) effects at the wafer level, which are induced by the interaction between the oblique incident EUV light and the patterned absorber with typical thickness values on the order of several wavelengths. We exploit the optical properties of the absorber material of the EUV mask as an M3D mitigation strategy. Using rigorous lithographic simulations, we screen potential single-element absorber materials for their optical properties and optimal thickness for minimum best focus variation through pitch at the wafer level. In addition, the M3D mitigation by absorber material is evaluated by process window comparison of foundry N5-specific logic clips. To validate the rigorous simulation predictions and test the processing feasibility of the alternative absorber materials, we have selected the candidate single elements nickel and cobalt for an experimental evaluation on wafer substrates. We present the film characterization as well as the first patterning tests of these single-element candidate absorber materials.
© 2017 Society of Photo-Optical Instrumentation Engineers (SPIE)
Vicky Philipsen, Kim Vu Luong, Laurent Souriau, Andreas Erdmann, Dongbo Xu, Peter Evanschitzky, Robbert W. E. van de Kruijs, Arash Edrisi, Frank Scholze, Christian Laubis, Mathias Irmscher, Sandra Naasz, Christian Reuter, Eric Hendrickx, "Reducing extreme ultraviolet mask three-dimensional effects by alternative metal absorbers," Journal of Micro/Nanolithography, MEMS, and MOEMS 16(4), 041002 (1 August 2017). https://doi.org/10.1117/1.JMM.16.4.041002 Submission: Received 17 May 2017; Accepted 6 July 2017
Submission: Received 17 May 2017; Accepted 6 July 2017

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