MRC for curvilinear mask shapes
A very practical challenge for putting masks with curvilinear shapes in production is the availability of reliable mask rule checks (MRC). The OPC engine not only needs to generate shapes which are manufacturable, the mask shop also needs a method of verifying that incoming mask data is manufacturable. For curvilinear mask shapes this is more challenging than for rectangular mask shapes, since simple width and space checks as used for rectangular masks are no longer sufficient.
In this paper, we discuss a comprehensive set of MRC limits and demonstrate the effectiveness of an MRC engine operating on curvilinear input data. Rules used here include minimum width of exposed features, minimum space between exposed features, minimum curvature of convex and concave shapes, as well as minimum area of exposed features.