Stochastic Printing Failures in EUV Lithography

This paper continues our work on what we call stochastic printing failures, i.e. random, non-repeating, isolated defects which we believe to be the result of the particle nature of light and matter, and of the probabilistic nature of their behavior and interactions. Examples of such failures are microbridges, locally broken lines and missing or merging contacts. The probability of such stochastic failures increases rapidly when a dimension in the pattern becomes very "small". We refer to this rapid increase as the "stochastic cliffs". In this paper we continue our exploration of the metrology for accurate mapping of these stochastic cliffs, for the case of simple L/S and contact-array patterns. We do this using a combination of CD-SEM, e-Beam Inspection (eBI) and Optical Defect Inspection measurements, according to the need and applicability. We will also show that away from the Cliffs we (sometimes) find a "Stochastic Floor", i.e. a constant level of stochastic failures of a given type. Next to failures counting, we introduce the size distribution of microbridges as a complementary metric. The examples given in this paper aim to clarify what the "stochastic landscape" can look like. Such measurements identify which failure types are the potential yield limiters of the intended application, and at which structures (pitches) and CDs they occur.