Strength analysis of EUV-exposed photo resists by AFM at 40 nm half pitch and below

Pattern collapse is one of the main contributors to photo resist pattern failure in high resolution optical and Extreme Ultra-Violet (EUV) lithography, and becomes progressively more prominent as the feature size is reduced and at smaller pitch. For resist development it is crucial to understand and be able to quantitatively measure the physical properties such as the intrinsic strength of the resist, in order to reduce the probability of collapse. In this paper, an existing scanning probe method is extended to encompass EUV-exposed resist features at smaller dimensions than what has previously been reported in literature. Along with a description of the method, we show with a beam-bending model that for a set of commercial resists a characteristic strength coefficient can be derived. (C) 2012 Elsevier B.V. All rights reserved.