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Nanometer Metrology of Periodic Structures With Ultrafast Optoacoustics

Published online by Cambridge University Press:  01 February 2011

Thomas J Grimsley ,
George Andrew Antonelli ,
Fan Yang ,
Humphrey J Maris  and
Arto Nurmikko
Thomas J Grimsley
Affiliation:
[email protected]
George Andrew Antonelli
Affiliation:
[email protected], Novellus, External Research & Development, Albany, New York, United States
Fan Yang
Affiliation:
[email protected], Brown University, Physics, 02912, Rhode Island, United States
Humphrey J Maris
Affiliation:
[email protected], Brown University, Physics, 02912, Rhode Island, United States
Arto Nurmikko
Affiliation:
[email protected], Brown University, Engineering, 02912, Rhode Island, United States
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Abstract

We present an optoacoustic method to non-destructively measure the average dimensions of a periodic array of simple structures with aspect ratios greater than 10:1, which are inaccessible to AFM techniques. The technique that we describe could be used as the basis of an inline metrology tool for wafer inspection. The samples examined were test structures with high precision lithographically defined lines of silicon dioxide deposited on a silicon substrate. The thickness of the silicon dioxide was around 400 nm, and the gaps between the lines ranged from 100 nm down to smaller than 40 nm. A drop of water was placed on the sample, and an optoacoustic transducer was placed on top; measurements were taken with a water thickness less than 1 micron between the optoacoustic transducer and the sample. The water filled the spaces between the lines due to the hydrophilic nature of the sample surface. Using the picosecond ultrasonics technique, acoustic pulses are generated in a special optoacoustic transducer, transmitted through a coupling fluid (water), scattered off of the sample being examined and then return to the transducer. The returning acoustic signal shows nanometer sensitivity to the height of the lines and the specific details of their profile.

Keywords

nanostructureacousticfluid
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1249: Symposia E/F – Advanced Interconnects and Chemical Mechanical Planarization for Micro-and Nanoelectronics , 2010 , 1249-F10-05
Copyright
Copyright © Materials Research Society 2010

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References

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