Method for measuring thickness of metal film of lithographic mask

A photolithography mask and thickness measurement technology, which is applied in the field of physical measurement, can solve the problem of not using two asymmetric double-sided metal-clad waveguide structures for measurement, and achieves the effects of simple method, convenient operation and noise elimination.

CN102478389AInactive Publication Date: 2012-05-30SHANGHAI OPTICAL LITHOGRAPHY ENG
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2012-05-30
Estimated Expiration
Not applicable · inactive patent

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Abstract

The invention relates to a method for measuring a thickness of a metal film of a lithographic mask and belongs to the field of physical measurement. The method comprises the following steps of: placing a prism of which the bottom surface is evaporated with a gold film close to a metal chromium surface of the mask so as to form a double-sided metal waveguide structure to be measured; selecting a laser wavelength and a polarization mode of an incident angle; receiving and recording the light intensity of a laser beam reflected from the bottom of a coupled apparatus or the light intensity of a laser beam transmitted from a lower metal film; changing the laser incident angle to obtain a curve of the light intensity and the incident angle; finding a resonance angle of absorption peaks of a guided mode and a width and a depth of the corresponding absorption peak; and calculating to obtain a refractive index and a thickness value of a thin film material. According to the invention, the high accuracy measurement is realized. The method is easy for operation and miniaturization.
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Description

[0001] Measuring method for metal film thickness of photolithography mask technical field

[0002] The invention relates to a measurement method, in particular to a method for measuring the thickness of a metal film of a photolithography mask, belonging to the field of physical measurement. Background technique

[0003] In the past 30 years, with the development of microelectronics technology, especially integrated circuits, the research and application of thin film thickness and key dimension line width measurement have made great progress. Among them, the attenuated total reflection method has been put into practice, and there are many reports on it. After literature search, it is found that the Chinese patent number is 02136611.X, and the patent name is: double-sided metal film waveguide measurement method and its device. This patent proposes a method for measuring the thickness of an optical film. In this method, the The measurement device is formed on both sides by eva...

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Embodiment Construction

[0025] As shown in the accompanying drawings, the technical solution of the present invention is achieved in this way. The device of the present invention is composed of a coupling device, an upper metal film, an air layer, a lower metal film, and a photolithographic plate metal substrate from top to bottom. The upper metal film, The air layer and the lower metal film are double-sided metal waveguide structures, and the upper and lower metal films are the upper and lower covering layers of the waveguide, and the light is coupled into the waveguide for transmission. The coupling device adopts devices such as high refractive index prism (n>1.5), grating and coupling waveguide, and the shape of the prism can be equilateral, isosceles, or cylindrical according to actual needs. The metal film on the upper layer can generally choose a metal that absorbs less at the working wavelength. The dielectric constant of the metal is related to the working wavelength, and the thickness of the ...