Method for optimizing laser nondestructive characterized Youngs modulus of membrane

A technology of Young's modulus and optimization method, which is applied in the direction of measuring devices, processing detection response signals, and using sound waves/ultrasonic waves/infrasonic waves to analyze solids.

Pending Publication Date: 2019-03-26
TIANJIN UNIV
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Problems solved by technology

Residual stress not only affects the characteristics of the film itself, but al

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  • Method for optimizing laser nondestructive characterized Youngs modulus of membrane
  • Method for optimizing laser nondestructive characterized Youngs modulus of membrane
  • Method for optimizing laser nondestructive characterized Youngs modulus of membrane

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Embodiment Construction

[0019] Based on the theory of acoustic elasticity, the present invention analyzes the ideal model of surface acoustic wave propagation in a film containing residual stress, studies the influence of residual stress on the measurement of Young's modulus of the film, and introduces the error criterion "ΔE / E" to describe the residual stress Influence on Young's modulus measurement. where ΔE is the difference between the Young's modulus represented by the same dispersion curve in the ideal model and in the residual stress model. The invention includes a calculation method for calculating the applicable range of the ideal model, within the range, the impact of residual stress on the measurement of Young's modulus of the film is less than 5%, which can be neglected. SiO 2 / Si structure as an example, the implementation scheme is as follows:

[0020] (1) SAW in SiO 2 / Si structure in the propagation model such as figure 1 , for the initial coordinates, the motion equation of the w...

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Abstract

The invention relates to a method for optimizing the characterized Youngs modulus of a membrane. The method comprises the following steps: calculating a range of residual stress, which has the influence on membrane Youngs modulus measurement to be less than 5 percent, to serve as the applicable range of an ideal model; controlling a laser to transmit a short-pulse laser beam with certain frequencyand energy by adopting a film/sample with a substrate structure, and generating an ultrasonic surface wave from the sample surface through the thermoelastic effect; acquiring an experimental frequency dispersion curve; contrasting the thickness of the film and residual stress value with the applicable range of the ideal model; and substituting other parameters including density, Youngs modulus, Poisson ratio of the film and substrate of the sample into the MATLAB ideal theoretical model, and finding out a Youngs modulus value of the theoretical frequency dispersion curve closest to the experimental frequency dispersion curve by changing the Youngs modulus value.

Description

technical field [0001] The invention belongs to the field of ultrasonic surface wave non-destructive testing, and relates to an optimization method for the characterization of the Young's modulus of a thin film. Background technique [0002] In the process of film production and preparation, residual stress will inevitably be introduced into the film. According to the form of action, the residual stress in the film can be generally divided into two types: tensile stress and compressive stress. Residual stress not only affects the characteristics of the thin film itself, but also seriously affects the quality and performance of thin-film structural devices. The principle of measuring the Young's modulus of a thin film by the ultrasonic surface wave method is that the ultrasonic surface wave is dispersed when it propagates in the layered structure of the film / substrate, and the surface wave velocity is not only related to the frequency, but also related to the thickness, dens...

Claims

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Application Information

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IPC IPC(8): G01N29/04G01N29/44
CPCG01N29/041G01N29/4472
Inventor 肖夏秦慧全
Owner TIANJIN UNIV
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