Understanding the influence of 3D sidewall roughness on observed line-edge roughness in scanning electron microscopy images

Research output: Chapter in Book/Conference proceedings/Edited volumeConference contributionScientificpeer-review

29 Downloads (Pure)

Abstract

Line-edge roughness (LER) is often measured from top-down critical dimension scanning electron microscope (CD-SEM) images. The true three-dimensional roughness profile of the sidewall is typically ignored in such analyses. We study the response of a CD-SEM to sidewall roughness (SWR) by simulation. We generate random rough lines and spaces, where the SWR is modelled by a known power spectral density. We then obtain corresponding CD-SEM images using a Monte Carlo electron scattering simulator. We find the measured LER from these images, and compare it to the known input roughness. We find that, for isolated lines, the SEM measures the outermost extrusion of the rough sidewall. The result is that the measured LER is up to a factor 2 less than the true on-wafer roughness. The effect can be accurately modelled by making a top-down projection of the rough edge. Our model for isolated lines works fairly well for a dense grating of lines and spaces, as long as the trench width exceeds the line height.

Original languageEnglish
Title of host publicationProceedings of SPIE
Subtitle of host publicationMetrology, Inspection, and Process Control for Microlithography XXXIV
EditorsOfer Adan, John C. Robinson
PublisherSPIE
Number of pages17
Volume11325
ISBN (Electronic)9781510634176
DOIs
Publication statusPublished - 2020
EventMetrology, Inspection, and Process Control for Microlithography XXXIV 2020 - San Jose, United States
Duration: 24 Feb 202027 Feb 2020

Publication series

NameMETROLOGY, INSPECTION, AND PROCESS CONTROL FOR MICROLITHOGRAPHY XXXIV
ISSN (Print)0277-786X

Conference

ConferenceMetrology, Inspection, and Process Control for Microlithography XXXIV 2020
CountryUnited States
CitySan Jose
Period24/02/2027/02/20

Keywords

  • Line edge roughness
  • Metrology
  • Monte Carlo methods
  • Scanning electron microscopy
  • Sidewall roughness

Fingerprint Dive into the research topics of 'Understanding the influence of 3D sidewall roughness on observed line-edge roughness in scanning electron microscopy images'. Together they form a unique fingerprint.

Cite this