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On the Characterization of Thin Film-only Mechanical Property Based on the Indentation Image Analysis

Published online by Cambridge University Press:  26 February 2011

Yun-Hee Lee
Affiliation:
uni44@kriss.re.kr, Korea Research Institute of Standards and Science, Division of Metrology for Quality Life, 1 Doryong-dong, Yuseong-gu, Daejeon, 305-340, Korea, Republic of, 82-42-868-5385, 82-42-868-5635
Yong-Il Kim
Affiliation:
yikim@kriss.re.kr, Korea Research Institute of Standards and Science, Division of Metrology for Quality Life, Daejeon, 305-340, Korea, Republic of
Hoon-Sik Jang
Affiliation:
hsjang@kriss.re.kr, Korea Research Institute of Standards and Science, Division of Metrology for Quality Life, Daejeon, 305-340, Korea, Republic of
Seung-Hoon Nahm
Affiliation:
shnahm@kriss.re.kr, Korea Research Institute of Standards and Science, Division of Metrology for Quality Life, Daejeon, 305-340, Korea, Republic of
Ju-Young Kim
Affiliation:
juyoung1@snu.ac.kr, Seoul National University, School of Materials Science and Engineering, Seoul, 151-742, Korea, Republic of
Dongil Kwon
Affiliation:
dongilk@snu.ac.kr, Seoul National University, School of Materials Science and Engineering, Seoul, 151-742, Korea, Republic of
Jae-il Jang
Affiliation:
jijang@hanyang.ac.kr, Hanyang University, Department of Materials Science and Engineering, Seoul, 133-791, Korea, Republic of
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Abstract

Conventional nanoindentation testing generally uses a peak penetration depth of less than 10 % of thin-film thickness in order to measure film-only mechanical properties, without considering the critical depth for a given thin film-substrate system. The uncertainties in this testing condition make hardness measurement more difficult. We propose a new way to determine the critical relative depth for general thin-film/substrate systems; an impression volume analyzed from the remnant indent image is used here as a new parameter. Nanoindents made on soft Cu and Au thin films with various indentation loads were observed by atomic force microscope. The impression volume calculated from 3D remnant image was normalized by the indenter penetration volume. This indent volume ratio varied only slightly in the shallow regime but decreased significantly when the indenter penetration depth exceeded the targeted critical relative depth. Thus, we determined the critical relative depth by empirically fitting the trend of the indent volume ratio and determining the inflection point. The critical relative depths for Cu and Au films were determined as 0.170 and 0.173, respectively, values smaller than 0.249 and 0.183 determined from the hardness variation of the two thin films. Hence the proposed indent volume ratio is highly sensitive to the substrate constraint, and stricter control of the penetration depth is needed to measure film-only mechanical properties.

Type
Research Article
Copyright
Copyright © Materials Research Society 2007

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