Random 2D Metal Single Patterning Capability Using 0.55NA EUV Lithography

Abstract

At advanced nodes, due to the resolution limitations of 0.33NA EUV lithography, metal layers are usually defined as unidirectional (1D) patterns to guarantee patterning fidelity on the wafer. Accordingly, multiple masks are required to print 2D patterns. However, 0.55NA EUV lithography, with its higher resolution capability, enables the opportunity for bidirectional (2D) metal layer patterning [2], which can significantly reduce process complexity and manufacturing costs. In previous studies [1, 10], unidirectional metal layer patterning has been extensively investigated, and by introducing alternative mask absorbers, 0.55NA EUV has demonstrated excellent single patterning quality down to pitch 20nm. In this paper, we focus on evaluating bidirectional random metal layer patterning capabilities using 0.55NA EUV lithography through Source-Mask Optimization (SMO). Inverse Lithography Technique (ILT) will be employed to assess and optimize the patterning performance of complex 2D metal structures under varying degrees of design rule aggressiveness, and the key imaging parameters will be used for the assessment.