Laser-based surface acoustic wave dispersion spectroscopy for extraction of thicknesses, depth, and elastic parameters of a subsurface layer: Feasibility study on intermetallic layer structure in integrated circuit solder joint

Abstract

Laser beam deflection in combination with optical heterodyne diffraction is used to detect surface acoustic waves that are generated by impulsive laser light on a Sn–CuxSny–Cu–Si multilayer structure with layer thicknesses of the order of 1 μm. The acoustic phase velocity dispersion curves of the lowest two-surface acoustic wave modes are determined by spectral analysis of the experimental signals. The sensitivity of the dispersive behavior to the thickness and elastic properties of the individual layers is analyzed on the basis of the experimental data and of simulated data with noise added. The elastic parameters of the CuxSny intermetallic alloy are determined. Statistical least squares and most squares uncertainties on all best fitting material parameters are determined, giving a quantitative measure of the feasibility of parameter extraction by this method. The feasibility of solving the inverse problem of elastic depth profiling of a multilayer by the proposed wideband and multimode SAW dispersion spectroscopy method is confirmed.

Thermoelastic Model for Impulsive Stimulated Scattering Monitoring the Evolution from Capillary to Rayleigh Type Wave Propagation on the Surface of Viscoelastic Materials Throughout the Glass Transition

“…When polarization selective detection is done, even information about the rotational relaxation can be extracted [7]. Also, in the reflection mode, the signal-to-noise ratios achieved by ISS in the heterodyne detection mode are quite satisfactory [1,2,28,31], even for rough samples [32].…”

“…ISS is a technique that has proven its value for the thermal and elastic characterization of bulk solids [26], thin coatings [27], intermediate layers in multilayered systems [28], bulk fluids [4], fluid-solid interface [6], and the free liquid surface [11][12][13]29]. In the employed ISS scheme shown in Fig.…”

Determination of elastic properties of a MnO2 coating by surface acoustic wave velocity dispersion analysis

“…From this 4D matrix, least squares (LS) and most squares (MS) curves 16 can be constructed for all parameters ( Figure 5). The LS curves were constructed by varying one parameter (e.g., E) and keeping all other parameters at the values that resulted in the best fit, ð à ; q à ; L à Þ.…”

“…ISTS has successfully been used to study SAW behavior and to probe material characteristics for a number of different configurations, in both solid and liquid materials. Characterization of bulk solids and liquids, [10][11][12][13] the study of acoustic waves at interfaces 14,15 and the investigation of thin (un)supported films 16,17 are just a few examples.…”

Temperature Dependent Elasticity of a Ni2MnGa Film as Measured by Impulsive Stimulated Scattering

“…It has proven to be an useful tool in the characterization of bulk solids [1,2], free liquid surfaces [3], thin films [4] and multilayered structures [5]. A more extensive review of the technique, applications and the relationship of ISS to other laser ultrasonic methods, e.g.…”