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21 March 2007 Design for manufacturing approach to second level alternating phase shift mask patterning
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A significant barrier to implementing APSM in volume production has been the expense of the mask. The cost of the mask is driven partially by the complexity of the two layer process flow required to make the mask. Typically, the 2nd level pattern is generated by upsizing the first level pattern of the pi apertures by a small amount in order to provide some overlay margin. The amount of upsizing is limited by the smallest chrome feature present in the pattern. The overlay margin between the first and 2nd level patterns can be improved by sizing the 2nd level more on larger chrome structures, when present. With a simple set of rules, it is possible to generate a 2nd level pattern with greater than ten times reduction in the number of corners, as measured by the number of vertices in the pattern, and minimize the number of marginal patterns in the design. This also has the beneficial side effect of significantly reducing the file size of the 2nd level pattern which can reduce the write time on some writers. Existing design rules can be exploited or additional rules imposed that can further improve the capability of the 2nd level APSM process. The right set of mask design rules can enable the use of lower fidelity writer for 2nd level patterning which can significantly reduce cost. The improved margin can increase yield and may even enable a less capable/expensive patterning tool to be used for 2nd level patterning.
© (2007) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Sven Henrichs, Mahesh Chandramouli, and Min Chun Tsai "Design for manufacturing approach to second level alternating phase shift mask patterning", Proc. SPIE 6521, Design for Manufacturability through Design-Process Integration, 65211W (21 March 2007);

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