Lithography Options for the 32 nm Half Pitch Node and Beyond

• Published in: IEEE transactions on circuits and systems. I, Regular papers Vol. 56; no. 8; pp. 1884 - 1891
• Main Authors: Ronse, K., Jansen, P., Gronheid, R., Hendrickx, E., Maenhoudt, M., Wiaux, V., Goethals, A.-M., Jonckheere, R., Vandenberghe, G.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-08-2009; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: 193 nm immersion lithography; 22 nm half pitch node; 32 nm half pitch node; Costs; Encounters; Extreme ultra-violet lithography; Immersion; Lenses; Liquids; Lithography; Manufacturing; Offset printing; Optical materials; Patterning; Production; Refractive index; Resists; Roughness; Ultraviolet sources
• ISSN: 1549-8328; 1558-0806
• DOI: 10.1109/TCSI.2009.2028417

Three major technological lithography options have been reviewed for high volume manufacturing at the 32 nm half pitch node: 193 nm immersion lithography with high index materials, enabling NA > 1.6; 193 nm double patterning and EUV lithography. In this paper the evolution of these three options over 2008 is discussed. The extendibility of these options beyond 32 nm half pitch is important for the final choices to be made. During 2008, the work on high index 193 nm immersion lithography has been stopped due to lack of progress in high index optical material and high index liquid development. Double patterning has made a lot of progress but cost concerns still exist. Preferred are those resists which support pattern or image freezing techniques in order to step away from the complex litho-etch-litho-etch approach and make double patterning more cost effective. For EUV, besides the high power light source, the resist materials need to meet very aggressive sensitivity specifications and need to maintain simultaneously performance in terms of resolution and line width roughness. Furthermore, EUV reticles encounter serious challenges, primarily related to mask defectivity.