CN-121978789-A - Preparation method of multilayer film plane window reflecting mirror film system

Abstract

The invention provides a preparation method of a multilayer film plane window reflecting mirror film system, which adopts a vacuum evaporation method, wherein the film system structure is G I (Hf-SiO 2 ) n I A, a reflecting film of the multilayer film plane window reflecting mirror film system adopts HfO 2 as a high refractive index material and adopts SiO 2 as a low refractive index material, wherein an HfO 2 layer is deposited by evaporating Hf in an oxygen-containing vacuum environment.

Inventors

• ZENG QIANG

Assignees

• 北京创思镀膜有限公司

Dates

Publication Date

20260505

Application Date

20260313

Priority Date

20250603

Claims (10)

1. 1. A preparation method of a multilayer film plane window reflecting mirror film system is characterized in that the film system structure of the reflecting film is G I (HfO 2 -SiO 2 ) n I A), the preparation method adopts a vacuum evaporation method, a predicted TOLLING value is used for correcting a plating process in the plating process of the reflecting film, wherein the predicted TOLLING value is obtained by carrying out grabbing for x times according to the average plating thickness when plating is carried out by adopting the same technical parameters as the actual plating process, and x is 2-4.
2. 2. The method of claim 1, wherein x is 3.
3. 3. The method according to claim 2, wherein the number of layers n of the reflective film is 80 to 160, preferably 100 to 140.
4. 4. The method according to claim 3, wherein the TOLLING values are obtained by refractive index contrast method, comprising the steps of plating a certain thickness of the film material on the glass substrate in advance before the final plating, measuring the residual reflectivity of the corresponding wave band, and determining TOLLING values by designing the difference between the designed value and the actual value by designing the curve of the contrast reflectivity.
5. 5. The method according to claim 4, wherein the thickness of the HfO 2 monolayer is 150 to 200nm and the thickness of the SiO 2 monolayer is 150 to 200nm.
6. 6. The method of claim 5, wherein the high refractive material layer is deposited by evaporating Hf in an oxygen-containing vacuum atmosphere having a vacuum of 2x 10 -3 ~6×10 -4 Pa and an oxygenation of 80 to 100sccm.
7. 7. The method according to claim 6, wherein the high refractive material layer and the low refractive material layer of the reflective film are formed by electron gun evaporation, the deposition rate is controlled to be 0.6-0.8A/s when the high refractive material layer is plated, and the deposition rate is controlled to be 5-6A/s when the low refractive material layer is plated.
8. 8. The method according to claim 7, wherein the deposition temperature during the plating of the reflective film is 200-250 ℃, the substrate 1 is etched for 10-15 min with a hall ion source before the plating, and the temperature is kept at 10-20 min ℃ under a vacuum of less than 2 x 10 -3 Pa and 200-250 ℃ before the plating.
9. 9. A planar window mirror, characterized in that it is produced by the production method according to any one of claims 1 to 8.
10. 10. Use of the preparation method according to any one of claims 1 to 8 for improving the preparation accuracy of a multilayer beam splitting film.

Description

Preparation method of multilayer film plane window reflecting mirror film system Technical Field The invention relates to the technical field of ultraviolet reflectors, in particular to a preparation method of a planar window reflector film system. Background The ultraviolet band plane window reflector is an optical element for reflecting ultraviolet light (the wavelength range is about 100 nm to 400 nm), and is widely applied to the fields of photoetching technology, space detection, synchronous radiation sources, gas monitoring and the like. Wherein the multilayer film planar window mirror enhances the reflectivity of a specific wavelength by utilizing an interference effect by alternately stacking high refractive index and low refractive index materials as reflective films. In order to meet the requirements of high reflectivity of deep ultraviolet and visible light, the design of the high-performance reflecting film is required to meet the following principles of (1) selecting a material combination with large difference between high and low refractive indexes, reducing the number of coating layers, reducing the preparation difficulty and the production cost, and (2) ensuring that the film material has extremely small absorption performance in deep ultraviolet from the perspective of a spectrum curve of the film so as to ensure the reflectivity. SiO 2 has small absorption coefficient at working wavelength, uniform particle growth, amorphous film structure, high laser damage threshold, and is an ideal low refractive index material. Considering the possible high-low refractive index difference and deep ultraviolet absorption, the available high refractive index materials are very limited, such as Ta 2O5、TiO2、Nb2O5 and other common low melting point materials, the absorptivity of the materials in deep ultraviolet is relatively large, and the energy accumulation in the laser irradiation process has obvious effect on film ablation. The high refractive index material with low absorptivity of deep ultraviolet, such as HfO 2、Al2O3、CaF2, has low refractive index, and is required to meet the requirement of high reflectivity, and has the problems of large number of layers, large plating difficulty, long plating time, easy curve deviation and the like. Disclosure of Invention The invention provides a preparation method of a multilayer film plane window reflecting mirror film system, which is used for solving the problem that curves are easy to deviate when HfO 2 is used as a high-refractive-index material in the prior art and realizing stable production of the high-reflectivity multilayer film plane window reflecting mirror film system. In a first aspect, the present invention provides a method for preparing a film system of a multilayer film plane window reflecting mirror, wherein the film system structure of the reflecting film is G (HfO 2-SiO2)n i a), the preparation method adopts a vacuum evaporation method, a predicted TOLLING value is used to correct a plating process in a plating process of the reflecting film, wherein the predicted TOLLING value is obtained by performing x times of grabbing according to a plating thickness average when plating is performed by using the same technical parameters as those of an actual plating process, and x is 2-4. TOLLING is the ratio of the actual thickness of the coating film to the design thickness, and the values can be grasped to correct the difference between the actual thickness of the coating film and the design thickness of the sample, and the invention finds that if the coating is performed by adopting the same technological parameters from the beginning to the end of the coating, the refractive index of the film material or the coating TOOLING can change, so that the spectrum curve can be left and right or high and low, the qualification rate of the spectrum curve is affected, and the deviation can be mainly related to the vacuum degree change caused by continuous vacuum extraction. Therefore, the invention improves the 'one parameter to the bottom' of the traditional process, and adopts the method of changing the process parameters to adjust the refractive index of the material to plate, so that the refractive index of the final reflecting mirror is closer to the design value. Preferably, in the above preparation method, x is 3. Preferably, in the above preparation method, the number of layers n of the reflective film is 80 to 160, preferably 100 to 140. When the number of the reflecting film layers is large, the plating time is obviously prolonged, the TOLLING value is easier to change, and the film layer plating is easier to deviate from the design in the whole plating process. Preferably, the TOLLING values are captured by refractive index contrast method, which comprises plating a certain thickness of the film material on the glass substrate in advance before formal plating, measuring residual reflectivity of corresponding wave band, and determining TOLLING va