Modeling the effect of subsurface interface defects on contact stiffness for ultrasonic atomic force microscopy
Author
Sarioglu, A. F.
Atalar, Abdullah
Degertekin, F. L.
Date
2004Source Title
Applied Physics Letters
Print ISSN
0003-6951
Electronic ISSN
1077-3118
Publisher
AIP Publishing LLC
Volume
84
Issue
26
Pages
5368 - 5370
Language
English
Type
ArticleItem Usage Stats
115
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Abstract
We present a model predicting the effects of mechanical defects at layer interfaces on the contact
stiffness measured by ultrasonic atomic force microscopy sAFMd. Defects at subsurface interfaces
result in changes at the local contact stiffness between the AFM tip and the sample. Surface
impedance method is employed to model the imperfections and an iterative algorithm is used to
calculate the AFM tip-surface contact stiffness. The sensitivity of AFM to voids or delaminations
and disbonds is investigated for film-substrate combinations commonly used in microelectronic
structures, and optimum defect depth for maximum sensitivity is defined. The effect of contact force
and the tip properties on the defect sensitivity are considered. The results indicate that the ultrasonic
AFM should be suitable for subsurface detection and its defect sensitivity can be enhanced by
adjusting the applied force as well as by judicious choice of the AFM tip material and geometry.
Keywords
DisbondsSubsurface detection
Subsurface interface
Surface impedance
Algorithms
Atomic force microscopy
Boundary conditions
Defects
Electronic structure
Iterative methods
Substrates
Ultrasonics
Stiffness