We report on the detection of diffraction gratings buried below a stack of tens of 18-nm-thick SiO2 and Si3N4 layers and an optically opaque metal layer, using laser-induced, extremely high-frequency ultrasound. In our experiments, the shape and amplitude of a buried metal grating are encoded on the spatial phase of the reflected acoustic wave. This grating-shaped acoustic reflection of the buried grating is detected by the diffraction of a delayed probe pulse. A detailed understanding of our measurements is essential for nanometrology applications in the semiconductor manufacturing industry, such as wafer alignment. We show that the complex shape of the diffracted signal as a function of time can be reproduced using a comprehensive numerical model that includes the generation, propagation, and optical detection of the acoustic waves. This allows us to identify the salient features in our measurements such as the presence of acoustic-wave-induced gratings inverted with respect to buried grating, the interference between the optical fields diffracted off multiple grating-shaped acoustic waves, and multiple thin dielectric layers behaving as a single effective acoustic medium. Our results show that laser-induced ultrasound is a promising technique for subsurface nanometrology applications.

Detection of hidden gratings through multilayer nanostructures using light and sound / Edward, Stephen; Zhang, Hao; Setija, Irwan; Verrina, Vanessa; Antoncecchi, Alessandro; Witte, Stefan; Paul Planken, And. - In: PHYSICAL REVIEW APPLIED. - ISSN 2331-7019. - 14:1(2020), pp. 1-16. [10.1103/PhysRevApplied.14.014015]

Detection of hidden gratings through multilayer nanostructures using light and sound

Vanessa Verrina;
2020

Abstract

We report on the detection of diffraction gratings buried below a stack of tens of 18-nm-thick SiO2 and Si3N4 layers and an optically opaque metal layer, using laser-induced, extremely high-frequency ultrasound. In our experiments, the shape and amplitude of a buried metal grating are encoded on the spatial phase of the reflected acoustic wave. This grating-shaped acoustic reflection of the buried grating is detected by the diffraction of a delayed probe pulse. A detailed understanding of our measurements is essential for nanometrology applications in the semiconductor manufacturing industry, such as wafer alignment. We show that the complex shape of the diffracted signal as a function of time can be reproduced using a comprehensive numerical model that includes the generation, propagation, and optical detection of the acoustic waves. This allows us to identify the salient features in our measurements such as the presence of acoustic-wave-induced gratings inverted with respect to buried grating, the interference between the optical fields diffracted off multiple grating-shaped acoustic waves, and multiple thin dielectric layers behaving as a single effective acoustic medium. Our results show that laser-induced ultrasound is a promising technique for subsurface nanometrology applications.
2020
acoustics; industrial physics; optics
01 Pubblicazione su rivista::01a Articolo in rivista
Detection of hidden gratings through multilayer nanostructures using light and sound / Edward, Stephen; Zhang, Hao; Setija, Irwan; Verrina, Vanessa; Antoncecchi, Alessandro; Witte, Stefan; Paul Planken, And. - In: PHYSICAL REVIEW APPLIED. - ISSN 2331-7019. - 14:1(2020), pp. 1-16. [10.1103/PhysRevApplied.14.014015]
File allegati a questo prodotto
File Dimensione Formato  
Edward_Detection_2020.pdf

accesso aperto

Note: https://doi.org/10.1103/PhysRevApplied.14.014015
Tipologia: Versione editoriale (versione pubblicata con il layout dell'editore)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 3.16 MB
Formato Adobe PDF
3.16 MB Adobe PDF

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1557602
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 17
  • ???jsp.display-item.citation.isi??? 12
social impact