Method for scanning ultrasonic microscope and measuring thickness, sound velocity, density and attenuation of thin material simultaneously

Abstract

The invention discloses a method for scanning ultrasonic microscope and measuring thickness, sound velocity, density and attenuation of a thin material simultaneously. The method includes: 1) the thin material is placed on the surface of a base material, an ultrasonic probe is located right above the base material and the thin material, ultrasonic echo signals s1 (t) and s2 (t) of the base material and the thin material are obtained; 2) deconvolution based on the wiener filtering and autoregressive spectral extrapolation technique is performed on the s2 (t) to obtain a signal h1 (t), and an initial value of acoustic transition time is selected; 3) initial values of other variables are selected, reflection coefficient frequency spectrum of the thin material is matched to obtain optimal values of acoustic impedance, acoustic transition time and acoustic attenuation coefficient of the thin material; 4) deconvolution based on the wiener filtering and autoregressive spectral extrapolation technique is performed on s1 (t)+s2 (t); and 5) the thickness, the sound velocity, the density and the attenuation of the thin material are calculated. Four-variable high-accuracy simultaneous measurement of the thin material can be achieved, and the problem of convergence domain is solved when the frequency spectrum is matched.

Description

technical field [0001] The invention relates to the field of measurement of thin-layer material properties based on a scanning ultrasonic microscope, in particular to a method for simultaneously measuring the thickness, sound velocity, density and attenuation of a thin-layer material with a scanning ultrasonic microscope. Background technique [0002] Scanning Ultrasonic Microscope (SAM: Scanning Acoustic Microscope) is widely used in non-destructive testing and evaluation of key electronic devices and precision mechanical components, and is also widely used in microscopic observation of biological tissues. [0003] At present, thin-layer materials such as films and coatings are widely used in chemical industry, machinery manufacturing, energy, aviation and other fields because of their unique properties (such as high strength, wear resistance, corrosion resistance, good heat dissipation, etc.). For example, the diamond film attached to the surface of the tool can effectivel...

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Problems solved by technology

[0018] However, the above-mentioned traditional least squares method fitting is prone to poor initial value selection, resulting in less than the true value of convergence, and the inverse solution process fails.

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