Optical evaluation of the flexural rigidity and residual stress in thin membranes: Picosecond transient grating measurements of the dispersion of the lowest-order Lamb acoustic waveguide mode

John A. Rogers, Gregory R. Bogart

Research output: Contribution to journalArticlepeer-review

Abstract

This article describes a convenient, noncontacting technique for determining the flexural rigidity and residual stress in thin membranes. The method was based on transient grating photoacoustics, also known as impulsive stimulated thermal scattering. Crossed laser pulses provided a coherent source of wavelength tunable acoustic modes in the membranes. Diffraction of a probe laser revealed the time dependence of these motions. The measured dispersion of the lowest-order Lamb mode at small acoustic wavevectors, coupled with classical plate theory, allowed the flexural rigidity and the residual stress to be determined. The technique, its accuracy, and spatial mapping capabilities were demonstrated through analysis of membranes designed for masks in next-generation lithography systems based on projected beams of electrons.

Original languageEnglish (US)
Pages (from-to)217-225
Number of pages9
JournalJournal of Materials Research
Volume16
Issue number1
DOIs
StatePublished - Jan 2001

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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