Optimization flows of source, mask and projection optics

摘要

Embodiments of the present invention provide methods for optimizing a lithographic projection apparatus including optimizing projection optics therein. The current embodiments include several flows including optimizing a source, a mask, and the projection optics and various sequential and iterative optimization steps combining any of the projection optics, mask and source. The projection optics is sometimes broadly referred to as “lens”, and therefore the optimization process may be termed source mask lens optimization (SMLO). SMLO may be desirable over existing source mask optimization process (SMO) or other optimization processes that do not include projection optics optimization, partially because including the projection optics in the optimization may lead to a larger process window by introducing a plurality of adjustable characteristics of the projection optics. The projection optics may be used to shape wavefront in the lithographic projection apparatus, enabling aberration control of the overall imaging process.

主权项

1. A method of improving a lithographic process for imaging a portion of a design layout onto a substrate using a lithographic projection apparatus comprising projection optics, the method comprising:
selecting a subset of patterns from the portion of the design layout and selecting an initial illumination source; simultaneously optimizing, by a hardware computer system, the subset of patterns and the illumination source; and optimizing, by the hardware computer system, a characteristic of the projection optics used to project the subset of patterns onto a radiation-sensitive substrate by using at least the optimized illumination source, wherein optimizing the characteristic of the projection optics comprises determining a phase shift to be introduced in the projection optics with respect to a phase of the optimized illumination source.