Film thickness monitoring method capable of increasing spectral characteristics of film

Abstract

The invention relates to a film thickness monitoring method capable of increasing spectral characteristics of film, for a computer-controlled coating device. The method comprises the following steps: (1) inputting coating parameters to a computer before coating; (2) selecting the monitoring wavelengths and monitoring glass number satisfying the limited conditions through the calculation of the computer to obtain a coating monitoring table of the coating system, wherein lambda Min<lambda<lambda Max and the coating monitoring table contains sequential films of the coating system, the corresponding monitoring wavelengths and monitoring glass serial numbers; and (3) coating and the like. By adopting the method, the monitoring wavelengths and required mininum monitoring glass number can be automatically selected; by adopting the proportional film thickness monitoring method, the film thickness monitoring error can be reduced, the film thickness monitoring precision can be increased and the normalized coating system and the non-normalized coating system can be monitored. Under the condition that the control precision of the film thickness monitoring system is not changed, the spectral characteristics of the film can be effectively increased.

Description

technical field [0001] The invention is related to film coating, and relates to a film thickness monitoring method, in particular to a film thickness monitoring method for improving film spectrum performance for a computer-controlled coating device to perform film coating. Background technique [0002] The thickness of the film decisively affects the optical properties of the film. Achieving precise control of film thickness is a key factor in the preparation of high-performance optical films. [0003] The methods of film thickness control usually include optical monitoring method and quartz crystal oscillation method. The optical monitoring method directly monitors the optical thickness of the film layer, which uses the principle that the transmittance (or reflectance) of the film changes with the change of the film thickness to realize the monitoring of the film thickness; the more commonly used in the optical monitoring method is the photoelectrode In the photoelectrode...

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Problems solved by technology

However, the quartz crystal oscillation method cannot directly reflect the optical thickness of the film. In the case of the same film quality and thickness, due to the instability of some parameters such as the coating environment, the optical properties of the evaporation material will also have certain differences. Stable, this will inevitably bring relatively large errors in the monitoring process

The photoelectrode value method takes the extreme point of film transmittance (or reflectance) as the stop point, but near the extreme point, the change of film transmittance (or reflectance) is close to zero, that is, the transmittance at this time (or reflectivity) is not sensitive to changes in thickness, which limits the monitoring accuracy of the photoelectrode value method, which is an inherent defect in the principle of the method

The photoelectrode value method requires the optical monitoring system to have a high signal-to-noise ratio, otherwise it is easy to misjudgment the extreme point; in addition, for different film systems, the optical monitoring signal changes with the change of film thickness. The monitoring of some film systems needs to replace the monitoring sheet during the monitoring process. However, because the thickness of the first layer of film plated on the new monitoring sheet is often too thick, this will cause thickness errors.

With the improvement of thin film spectral performance requirements, the photoelectrode value method can no longer meet the requirements of high-precision film thickness monitoring

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