Stochastic simulation and calibration of organometallic photoresists for extreme ultraviolet lithography

Abstract

Organometallic photoresists are being pursued as an alternative photoresist material to push the current extreme ultraviolet lithography (EUVL) to the next generation of high-NA EUVL. In order to improve the photoresist performance, an understanding of the photoresist's response to different process conditions is required. In this endeavor, a stochastic development model is implemented, integrated into full photoresist process steps, and applied for photoresist performance investigations. The model is applied to Inpria-YA photoresist, which works mainly by the process of aggregation. Previously published modeling approaches for metal-organic photoresists assume that the development characteristics of these materials depend only on the size of the created oxo-clusters. In contrast to that, we propose a modeling approach that provides a more detailed description of the interaction among the developer, ligands, and oxo-bonds. Further, the calibration procedures conducted to extract the model parameters to match experimental data are discussed. The model approximated the experimental data with CD RMSE and LWR RMSE of 0.60 and 0.40 nm, respectively. We also investigated the impact of photoresist parameters on the process metrics, line width roughness (LWR), critical dimension (CD), doseto-size (DtS), and exposure latitude (EL) with the calibrated model. The investigation shows that details of the interaction of photoresist and developer, especially, the so-called development critical value, have a significant impact on the LWR and DtS. © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

Applying stochastic simulation to study defect formation in EUV photoresists

“…This method is generally applicable to stochastic process models such as Belete's stochastic organometallic photoresist model. 19) The meaning of the seeds is dependent upon the stochastics steps that are part of the modeled process. Therefore, different resist types with different stochastic processes and mechanisms may have different results than presented here.…”

Lithography in a quantum world

“…43) More studies on the development of EUV resists will likely be useful, including those that focus on the development of non-CARs, as the limited research in this area indicates that greater capability might be attained by considering the resist development process. 44) Alternatives to tetramethyl ammonium hydroxide developers are also being considered, as they have shown potential to improve the lithographic process. 45) This is an approach worth pursuing further, as installing an additional developer distribution system that costs hundreds of thousands of dollars would be worthwhile to extend the performance of exposure tools that cost hundreds of millions of dollars.…”

Chemical Mechanisms of Metal-Based Extreme Ultraviolet Resists

“…It is difficult, however, to extract information on the structure of the material that remains in the exposed film. In simulation studies, it is assumed that after breaking of tincarbon bonds, cross-linking between cages occurs, leading to the observed negative tone resist behavior [30,33,34]. The detailed chemical structures of the primary photoproducts, and the exact way they cross-link in the solid resist films, are still unknown.…”