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1 January 2009 Double patterning lithography for 32 nm: critical dimensions uniformity and overlay control considerations
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Double patterning lithography (DPL)-either with two litho and two etches or through the use of a sacrificial spacer-are comparable in complexity and process control requirements. Since critical dimensions uniformity (CDU) and overlay requirements are considerably tighter than in single exposure, they present tougher challenges to process control, metrology, and integration, but seem feasible for 32-nm node. We study CDU and overlay requirements and performance at 32-nm-hp resolution for dual litho-etch and sacrificial spacer schemes. We bring in three particular aspects of CD control: the existence of multiple populations of lines and spaces, overlay entanglement into CDU performance, and the mechanism of doubled-pitch pattern generation from uncorrelated left and right edges, Accordingly, active compensation schemes are proposed to bring together these multiple CDU populations in order to achieve the typical 10% CD tolerance of the final pattern. Experimental results confirmed our assumptions of CDU-overlay entanglement and existence of multiple CD populations of lines and spaces. We present CDU results from before and after applying CD compensation schemes to improve CDU and overlay performance through active feed forward corrections. Results confirm the gain in improving statistical and spatial CD distribution to meet control levels required at 32-nm design rules: 2-nm CDU control per population, 3-nm CDU control for two adjacent lines, or spacer CD populations with 3-nm single machine overlay, all of them being demonstrated on multiple wafers and immersion scanners.
©(2009) Society of Photo-Optical Instrumentation Engineers (SPIE)
Jo M. Finders, Mircea V. Dusa, Bert Vleeming, Birgitt Hepp, Mireille Maenhoudt, Shaunee Cheng, and Tom Vandeweyer "Double patterning lithography for 32 nm: critical dimensions uniformity and overlay control considerations," Journal of Micro/Nanolithography, MEMS, and MOEMS 8(1), 011002 (1 January 2009).
Published: 1 January 2009

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