Dual wavelength antireflection film for excimer laser and optical film thickness monitoring system

Abstract

The invention discloses a dual wavelength antireflection film for excimer laser and an optical film thickness monitoring system that are applied to an excimer laser device compatible with 193 nm and 248 nm deep ultraviolet. The dual wavelength antireflection film for the excimer laser comprises a substrate and a multilayer film arranged on the substrate, wherein the multilayer film is formed by alternating stacking high refractive index films and low refractive index films, each high refractive index film is made of lanthanum fluoride, each low refractive index film is made of magnesium fluoride, and the multilayer film has 4 to 10 layers. The optical film thickness monitoring system comprises an electron-beam evaporation source, a thermal resistance evaporation source and a plated substrate; a baffle plate is arranged between the electron-beam evaporation source as well as the thermal resistance evaporation source and a plated substrate. The dual wavelength antireflection film applied to deep ultraviolet excimer laser ranges from 193 nm to 248 nm and is very low in residual reflectivity of a substrate surface, and minimum absorbing and scattering loss can be realized.

Description

technical field [0001] The invention relates to the field of deep ultraviolet excimer laser instruments, in particular to a dual-wavelength anti-reflection coating and an optical film thickness monitoring system for excimer lasers. Background technique [0002] Excimer laser is a kind of gas laser, its working gas is mainly composed of inert gas atoms argon (Ar), krypton (Kr), xenon (Xe) with very stable chemical properties under normal conditions and halogen atoms fluorine (F ), chlorine (Cl), bromine (Br), and iodine (I). Inert gas atoms generally do not form molecules with other atoms, but if they are mixed with halogen atoms and excited in the form of electric discharge, excited state molecules can be produced. When the excited state molecules transition back to the ground state, they are reduced to atoms again and emit photons, which are amplified by the resonant cavity and then emit laser light. Because the molecules in this excited state are fleeting and their lifet...

AI Technical Summary

Problems solved by technology

However, in this band, not only highly transparent substrate materials are very limited, but also applicable thin film materials are also very limited, especially high refractive index materials

What's more, even if there are only a few optional materials, since the photon energy is very close to the electronic bandgap of the material, it will produce high absorption, and the wavelength is very short, and the surface scattering is also very high. Therefore, the optical loss is very large, which not only causes the transmittance to be greatly reduced, but also causes the damage of the high-energy laser to the film. Because of this, reducing the optical loss of the film has become a difficult point in the design of deep ultraviolet excimer laser thin film devices. This is what the present invention is waiting for. Core issues to explore and solve

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