1 May 2017 Assessment of light source bandwidth impacts on image contrast enhancement using process window discovery
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The performance requirements of advanced semiconductor technology nodes necessitate the use of complex processing methods that push patterning beyond the physical limits of DUV immersion lithography (ArFi). Specifically, aggressive process window and yield specifications put tight requirements on scanner imaging performance.

Accurate identification of process windows can be accomplished using KLA-Tencor’s fixed focus offset conditions and Process window Discovery (PWD) methodology[1]. The PWD methodology makes use of a modulated wafer layout to enable inspection comparing nominal to modulated conditions. KLA-Tencor’s Broadband plasma (BBP) inspection technology is used to compare the nominal conditions to each experimental condition and to identify systematic defects. The identification of systematic defects is enabled by the PWD method by first discovering potential patterns of interest and then generating NanopointTM care areas around every occurrence of the patterns of interest. This allows identification of critical systematic structures that may have the same design intent but do not repeat in the same X,Y locations within a device. This approach maximizes the inspection sensitivity on each structure type, accurately identifies the edge of the process window in focus and dose, and enables study of the sensitivity of fixes process offsets (such as light source bandwidth).

In this study, a tunable DUV light source bandwidth technique and the PWD methodology are used to study the light source E95 bandwidth impact on Metal layer features from an imec 10 nm node logic-type test vehicle.
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Paolo Alagna, Paolo Alagna, Greg Rechtsteiner, Greg Rechtsteiner, Will Conley, Will Conley, Andrew Cross, Andrew Cross, Kaushik Sah, Kaushik Sah, Sandip Halder, Sandip Halder, } "Assessment of light source bandwidth impacts on image contrast enhancement using process window discovery", Proc. SPIE 10147, Optical Microlithography XXX, 101471X (1 May 2017); doi: 10.1117/12.2260314; https://doi.org/10.1117/12.2260314

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