System for Young modulus measurement of film

Abstract

The invention discloses a system for Young modulus measurement of a film. The system comprises a pulsed laser, wherein the pulsed laser emits pulse laser, which is divided into 7/10 pulse laser and 3/10 pulse laser by a 3:7 spectroscope after being collimated and broadened by a first beam expander, and the 7/10 pulse laser is focused on the surface of a sample under test through a cylinder focusing lens to generate an acoustic surface wave signal under excitation; and the acoustic surface wave signal is converted into an electrical signal through a first detection channel and/or a second detection channel, and the electrical signal is output to a computer for processing after being displayed by an oscillograph. The system not only has the advantages of large signal amplitude, high applicability in testing environment with large disturbance and the like of the piezoelectric laser acoustic surface wave detection technology, but also inherits the advantages of rapid, accurate and non-contact measurement and high signal to noise ratio and the like of the difference confocal laser acoustic surface wave detection technology; and the system has higher applicability and wider range of applicability. Meanwhile, based on the advantage of high measurement bandwidth of the difference confocal laser acoustic surface wave detection technology, the measurement resolution is greatly improved.

Description

technical field [0001] The invention relates to the field of measuring Young's modulus of thin films by laser ultrasonic technology, in particular to a system for measuring Young's modulus of thin films. Background technique [0002] In recent years, laser ultrasonic technology has attracted extensive attention in the measurement of mechanical properties such as Young's modulus of thin films. In laser ultrasonic systems, surface acoustic wave detection technologies have emerged in an endless stream. In the current technology, piezoelectric laser surface acoustic wave detection technology based on PVDF (polyvinylidene fluoride) film is widely used. PVDF piezoelectric film has good acoustic impedance matching characteristics, large response bandwidth, and high electromechanical conversion sensitivity. , so that the piezoelectric laser surface acoustic wave detection system based on PVDF film has a measurement bandwidth much higher than that of the general optical detection sys...

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Problems solved by technology

[0004] Although the above two surface acoustic wave detection technologies are superior to other detection technologies in terms of thin film Young's modulus measurement, they have their own shortcomings in some special samples and special scene tests.

For example: the four-quadrant surface acoustic wave detection announced in the piezoelectric detection device based on PVDF piezoelectric film LSAW positioning (publication number: CN102252967A, publication date: November 23, 2011), although it improves the measurement to some extent Accuracy, but it is still a contact detection, it cannot be used to measure samples with soft materials and high porosity, and it is difficult to apply to the ultra-clean environment required in integrated circuits; LSAW positioning measurement system based on Sagnac interferometer (public number: CN102221397A, publication date: October 19, 2011), although the method of positioning first and detecting later can accurately locate the position of the surface acoustic wave in time, so as to perform higher-precision measurement, it is always based on optics Non-contact measurement, cannot be used to measure samples with low reflectance and high transparency, and is easily affected by interference such as noise in the environment

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