Nanoscale elastic-property measurements and mapping using atomic force acoustic microscopy methods

We describe a dynamic atomic force microscopy (AFM) method for measuring the elastic properties of surfaces, thin films and nanostructures at the nanoscale. Our approach is based on atomic force acoustic microscopy (AFAM) techniques and involves the resonant modes of the AFM cantilever in contact mode. From the frequencies of the resonant modes, the tip–sample contact stiffness k* can be calculated. Values for elastic properties such as the indentation modulus M can be determined from k* with appropriate contact-mechanics models. We present the basic principles of AFAM and explain how it can be used to measure local elastic properties with a lateral spatial resolution of tens of nanometres. Quantitative results for a variety of films as thin as 50 nm are given to illustrate our methods. Studies related to measurement accuracy involving the effects of film thickness and tip wear are also described. Finally, we discuss the design and use of electronics to track the contact-resonance frequency. This extension of AFAM fixed-position methods will enable rapid quantitative imaging of nanoscale elastic properties.

[1]  Amelio,et al.  Quantitative determination of contact stiffness using atomic force acoustic microscopy , 2000, Ultrasonics.

[2]  G. Palumbo,et al.  On the contribution of triple junctions to the structure and properties of nanocrystalline materials , 1990 .

[3]  Joseph A. Turner,et al.  Atomic force acoustic microscopy methods to determine thin-film elastic properties , 2003 .

[4]  Kazushi Yamanaka,et al.  Quantitative material characterization by ultrasonic AFM , 1999 .

[5]  G. Pharr,et al.  An improved technique for determining hardness and elastic modulus using load and displacement sensing indentation experiments , 1992 .

[6]  Mathias Göken,et al.  Imaging and measurement of local mechanical material properties by atomic force acoustic microscopy , 2002 .

[7]  Kathryn J. Wahl,et al.  Quantitative imaging of nanoscale mechanical properties using hybrid nanoindentation and force modulation , 2001 .

[8]  D. Maugis.  Adhesion of spheres : the JKR-DMT transition using a dugdale model , 1992 .

[9]  Donna C. Hurley,et al.  Elastic-property measurements of ultrathin films using atomic force acoustic microscopy , 2005 .

[10]  Oleg Kolosov,et al.  Nanometer-scale mechanical imaging of aluminum damascene interconnect structures in a low-dielectric-constant polymer. , 2002 .

[11]  Kei Kobayashi,et al.  Resonance tracking ultrasonic atomic force microscopy , 2002 .

[12]  Xi-Qiao Feng,et al.  Interface effects on effective elastic moduli of nanocrystalline materials , 2003 .

[13]  Keiichi Nakamoto,et al.  Resonance frequency and Q factor mapping by ultrasonic atomic force microscopy , 2001 .

[14]  Gerold A. Schneider,et al.  High-resolution characterization of piezoelectric ceramics by ultrasonic scanning force microscopy techniques , 2002 .