Method for representing residual stress of film

Abstract

The invention relates to a method for representing a residual stress of a film. The method comprises that a sample wafer of a film / substrate structure is used, a laser is controlled to emit a burst-pulse laser beam of certain frequency and energy, a linear laser beam is gathered in the surface of the sample wafer, and the surface of the sample wafer generates surface supersonic waves; a piezoelectric transducer carries out detection and collects discrete time-domain voltage signals; an experimental dispersion curve is obtained; modeling is carried out, and a theoretical dispersion curve of a film / substrate model in a residual-stress-free state is obtained; and the experimental dispersion curve is compared with the theoretical dispersion curve, a residual stress magnitude sequence of films of sample wafers is determined qualitatively. The residual stress of the film can be detected rapidly and losslessly.

Description

technical field

[0001] The invention belongs to the field of thin film characteristic characterization, and relates to a method for non-destructive detection of thin film residual stress by ultrasonic surface wave technology. Background technique

[0002] The residual stress in the film is divided into compressive stress and tensile stress in terms of the external effect of force. When the compressive stress is too large, the film will buckle, which will weaken the adhesion of the film and separate the film from the substrate; When the tensile stress is too large, the film will wrinkle or even crack. If the excessive residual stress in the thin film cannot be detected in time during the manufacturing process of the integrated circuit and the next step of work is continued, the performance of the integrated circuit will inevitably be seriously affected. Therefore, the detection of residual stress in thin films is of great significance. The principle of ultrasonic surface wa...

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