Manufacturing of roughness standard samples based on ACF/PSD model programming

Abstract

Currently, Line Edge Roughness (LER) and Line Width Roughness (LWR) control presents a huge challenge for the lithography step in microelectronic industries. For advanced nodes, this morphological aspect reaches the same order of magnitude than the Critical Dimension, which leads to an increased power consumption by transistors and devices. Hence, the control of roughness needs an adapted metrology. This study proposes to manufacture roughness standard samples and their validation. These samples can be used as standards to evaluate the capabilities of several tools. The preliminary part of this study has been carried out with periodical roughness sample to demonstrate the metrology approach. Further, programming of roughness based on Power Spectral Density (PSD) with Auto-Correlation Function (ACF) model is used to achieve roughness close to the real roughness case. A description of how design programmed roughness has been made and its exposition in the real conditions are detailed in this study. Moreover, a specific methodology of control has been developed, the results obtained have been compared with design inputs and mostly validated by experimental processes. This work represents the first step of manufacturing roughness standard samples based on PSD model design.