Analytical calculation on the determination of steep side wall angles from far field measurements

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Abstract

In the semiconductor industry, the performance and capabilities of the lithographic process are evaluated by measuring specific structures. These structures are often gratings of which the shape is described by a few parameters such as period, middle critical dimension, height, and side wall angle (SWA). Upon direct measurement or retrieval of these parameters, the determination of the SWA suffers from considerable inaccuracies. Although the scattering effects that steep SWAs have on the illumination can be obtained with rigorous numerical simulations, analytical models constitute a very useful tool to get insights into the problem we are treating. In this paper, we develop an approach based on analytical calculations to describe the scattering of a cliff and a ridge with steep SWAs. We also propose a detection system to determine the SWAs of the structures.

Original languageEnglish
Article number065601
Number of pages12
JournalJournal of Optics (United Kingdom)
Volume20
Issue number6
DOIs
Publication statusPublished - 2018

Keywords

  • optical metrology
  • optical scattering
  • side wall angle retrieval

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