阅读说明：本技术 一种用于蓝宝石基底的增透薄膜及其制备方法 (Anti-reflection film for sapphire substrate and preparation method thereof ) 是由 徐照英 刘垚 王锦标 苏永要 于 2020-07-27 设计创作，主要内容包括：本发明提供一种用于蓝宝石基底的增透薄膜,该增透薄膜包括五层薄膜层,其由蓝宝石材料基面(1)向外依次为SiO<Sub>2</Sub>薄膜层(2)、第一SiO<Sub>x</Sub>N<Sub>y</Sub>薄膜层(3)、第二SiO<Sub>x</Sub>N<Sub>y</Sub>薄膜层(4)、第三SiO<Sub>x</Sub>N<Sub>y</Sub>薄膜层(5)、第四SiO<Sub>x</Sub>N<Sub>y</Sub>薄膜层(6)；该增透薄膜通过平衡磁控溅射方法制备SiO<Sub>2</Sub>薄膜层(2)以及通过氮气、氧气以及氩气的不同速率制备氮元素的原子百分数依次递减、氧元素的原子百分数依次递增的SiO<Sub>x</Sub>N<Sub>y</Sub>薄膜层。该增透薄膜有效提高蓝宝石材料在红外波段的透过率、降低其反射率,使得蓝宝石材料整体具有较小的吸收、散射特性；同时,该增透薄膜与蓝宝石基底结合强度高、致密度高、结合牢靠,能有效用于军用光电装备等高强度领域,使用寿命长。(The invention provides an anti-reflection film for a sapphire substrate, which comprises five film layers, wherein SiO is sequentially arranged from a sapphire material basal plane (1) to the outside 2 A thin film layer (2) and a first SiO x N y A thin film layer (3) and second SiO x N y A thin film layer (4) and a third SiO x N y A thin film layer (5) and fourth SiO x N y A film layer (6); the anti-reflection film is used for preparing SiO by a balanced magnetron sputtering method 2 A film layer (2) and SiO prepared by sequentially decreasing the atomic percent of nitrogen and increasing the atomic percent of oxygen through different rates of nitrogen, oxygen and argon x N y A thin film layer. The anti-reflection film effectively improves the transmittance of the sapphire material in an infrared band and reduces the reflectivity of the sapphire material, so that the sapphire material has small absorption and scattering properties; meanwhile, the anti-reflection film is high in bonding strength with a sapphire substrate, high in density and firm in bonding, can be effectively used in high-strength fields such as military photoelectric equipment and is long in service life.)

1. An antireflection film for a sapphire substrate, characterized in that: the antireflection film comprises five film layers; the five thin film layers are sequentially SiO from the sapphire material base surface (1) to the outside₂A thin film layer (2) and a first SiO_xN_yFilm layer (3), secondSiO 2_xN_yA thin film layer (4) and a third SiO_xN_yA thin film layer (5) and fourth SiO_xN_yA film layer (6); wherein the first SiO_xN_yThin film layer (3) to fourth SiO_xN_yThe atomic percentages of nitrogen and oxygen in the thin film layer (6) are sequentially decreased and increased, and the atomic percentages of nitrogen and oxygen should be no more than 40at.% and 60at.%, respectively.

2. An antireflection film for a sapphire substrate according to claim 1, wherein: the SiO₂The thickness of the thin film layer (2) can be 130-170 nm.

3. An antireflection film for a sapphire substrate according to claim 1, wherein: the first SiO_xN_yA thin film layer (3) and second SiO_xN_yA thin film layer (4) and a third SiO_xN_yA thin film layer (5) and fourth SiO_xN_yThe thickness of the thin film layer (6) can be 10-30 nm, 40-85 nm, 90-140 nm and 146-200 nm respectively.

4. The method for preparing an antireflection film for a sapphire substrate according to claim 1, wherein the method comprises the following steps: firstly, cleaning a sapphire material and a target material to remove surface impurities; then SiO is carried out by adopting non-equilibrium magnetron sputtering equipment₂Depositing the thin film layer (2), and introducing oxygen and argon into a gas source; redepositing SiO_xN_yThe thin film layer is filled with argon, oxygen and nitrogen as gas sources, and the first SiO is deposited in sequence by adjusting the gas flow rate of the nitrogen, the oxygen and the argon_xN_yA thin film layer (3) and second SiO_xN_yA thin film layer (4) and a third SiO_xN_yThin film layer (5) and fourth SiO_xN_yA film layer (6); and obtaining the anti-reflection film.

5. According toThe method for preparing an antireflection film for a sapphire substrate according to claim 4, wherein the method comprises the following steps: the specific steps of the cleaning are as follows: firstly, cleaning a sapphire material by adopting absolute ethyl alcohol, then placing the cleaned sapphire material on a sample table of a vacuum chamber of non-equilibrium magnetron sputtering equipment, and taking silicon (99.99%) as a target material; the vacuum chamber was closed and evacuated to 3.0x10^-3After Pa, turning on a bias power supply, applying 750-850V direct current voltage and 90-110V bias voltage on the sapphire material, opening an air valve, continuously introducing argon gas, enabling the flow of the argon gas to be 45-55 sccm, cleaning the sapphire material for 18-22 min, and then turning off the power supply; and then turning on a target power supply, applying a current of 0.5A to carry out pre-sputtering cleaning on the target for 9-11 min, and removing surface impurities.

6. The method for preparing an antireflection film for a sapphire substrate according to claim 4, wherein the method comprises the following steps: the SiO₂The deposition of the thin film layer (2) is specifically as follows: after cleaning the substrate material, introducing oxygen, wherein the introduction amount of the oxygen is 55-65 sccm, then introducing argon, adjusting the deposition temperature to be 170-190 ℃ by using a heating device and using a high-purity Si (99.99%) target as a cathode when the air pressure of a vacuum chamber rises to 1.0-1.5 Pa, adjusting the negative bias to be 48-52V, turning on a target sputtering power supply, setting the current to be 0.6-0.8A, and depositing for 35-45 min.

7. The method for preparing an antireflection film for a sapphire substrate according to claim 4, wherein the method comprises the following steps: the SiO_xN_yThe deposition of the thin film layer is specifically as follows: adjusting the pressure of an unbalanced magnetron sputtering device to be 5x10^-3Pa, introducing nitrogen, oxygen and argon; when the air pressure of a vacuum chamber rises to 1.0-1.5 Pa, taking a high-purity Si (99.99%) target as a cathode, adjusting the deposition temperature to 170-190 ℃ through a heating device, adjusting the negative bias to 48-52V, turning on a target sputtering power supply, and setting the current to 0.6-0.8A; by controlling the flow rate of nitrogen, oxygen and argon, SiO with different nitrogen content and oxygen content is deposited_xN_yA thin film layer.

Technical Field

The invention relates to the technical field of optical films, in particular to an anti-reflection film for a sapphire substrate and a preparation method thereof.

Background

Sapphire crystal-the hardest oxide crystal, is alumina (Al)₂O₃) Most basic single crystal morphology. The sapphire optical material is widely applied to military technical fields such as submarine photoelectric masts, land-based photoelectric countermeasures, airborne photoelectric pods, large-scale transport machine visible windows, missile hoods and the like due to excellent physical properties (high hardness, high bending strength, wind and sand resistance, high temperature resistance, corrosion resistance, good optical properties, excellent electrical insulation performance and the like), and is a window material, a high-quality optical material, a wear-resistant bearing material and a substrate material of infrared devices, missiles, submarines, satellite space technologies, detection, high-power strong laser and the like.

However, sapphire still encounters some technical difficulties in practical application, for example, sapphire material shows different degrees of lattice vibration absorption above the 4.0 μm band of the medium wave, and the reduction amplitude and thickness are obviously related, which limits the application of sapphire in the infrared band to some extent. The antireflection film, also called as an antireflection film, has the main function of reducing or eliminating the reflected light from optical surfaces such as lenses, prisms, plane mirrors and the like, thereby increasing the light transmission of the elements and reducing or eliminating the stray light of the system. The prior art generally eliminates the limitation on the infrared band by preparing an antireflection film on the surface of sapphire to reduce the reflectivity and increase the transmittance of the sapphire.

However, the sapphire material used as the multispectral hard protection window not only requires good optical performance, but also needs a compact, firm and wear-resistant film layer to meet the actual application requirements of military optoelectronic equipment; however, in the prior art, due to the transverse accumulation of internal stress and the corrosion of external severe temperature impact and high-humidity and high-salt environment, the anti-reflection and anti-reflection film for the sapphire substrate often causes the effective service life of the film layer to be obviously reduced, the bonding strength between the film layer and the sapphire substrate to be reduced, the structural stability of the film layer to be poor, and even the film layer to have the phenomena of corrosion spot, cracking, falling off and the like.

Disclosure of Invention

In view of the problems in the prior art, an object of the present invention is to provide an anti-reflection film for a sapphire substrate, which utilizes the principle that the refractive index changes continuously, so as to improve the transmittance of the infrared band and reduce the reflectance thereof, so that the sapphire material has small absorption and scattering properties as a whole; meanwhile, the anti-reflection film has high bonding strength with the sapphire substrate and high density, can effectively avoid temperature impact and corrosion in a high-humidity high-salt environment, and avoids the phenomena of film falling and cracking.

The invention also aims to provide a preparation method of the anti-reflection film for the sapphire substrate.

The purpose of the invention is realized by the following technical scheme:

an antireflection film for a sapphire substrate, characterized in that: the antireflection film comprises five film layers; the five thin film layers are sequentially SiO from the sapphire material base surface to the outside₂Thin film layer, first SiO_xN_yThin film layer, second SiO_xN_yThin film layer, third SiO_xN_yThin film layer, fourth SiO_xN_yA thin film layer; wherein the first SiO_xN_yThin film layer to fourth SiO_xN_yThe atomic percent of nitrogen elements in the thin film layer is sequentially decreased and the atomic percent of oxygen elements in the thin film layer is sequentially increased, and the atomic percent of the nitrogen elements is not more than 40at.%, and the atomic percent of the oxygen elements is not more than 60 at.%.

For further optimization, the SiO₂The thickness of the thin film layer is 130-170 nm.

For further optimization, the first SiO_xN_yThin film layer, second SiO_xN_yThin film layer, third SiO_xN_yThin film layer, fourth SiO_xN_yThe thickness of the thin film layer is 10-30 nm, 40-85 nm, 90-140 nm and 146-200 nm respectively.

For further optimization, the first SiO_xN_yThe atomic percent of nitrogen element and the atomic percent of oxygen element in the film layer are respectively 38-40 at.% and 13-15 at.%; the second SiO_xN_yThe atomic percent of nitrogen element and the atomic percent of oxygen element in the film layer are respectively 28-30 at.% and 28-30 at.%; the third SiO_xN_yThe atomic percent of nitrogen element and oxygen element of the thin film layer are respectively 18-20 at.% and 43-45 at.%; the fourth SiO_xN_yThe atomic percent of nitrogen element and the atomic percent of oxygen element in the film layer are respectively 8-10 at.% and 58-60 at.%.

The silicon dioxide has the characteristics of high melting point, firm film layer, wear resistance, corrosion resistance, strong protective capability, less scattering and absorption of light and the like, and the bonding strength of the film layer and the substrate is increased by preparing the silicon dioxide film layer on the sapphire substrate, so that the film layer is prevented from falling off from the substrate.

SiO_xN_yThe refractive index of the film is gradually reduced along with the increase of the content of the oxygen element, and the refractive index is gradually reduced along with the reduction of the content of the nitrogen element; the invention uses multilayer SiO with refractive index gradually reduced from inner layer to outer layer_xN_yThin film layer matching SiO₂The film layer enables the refractive index to continuously change along the normal direction of the surface of the film layer and keeps unchanged in the direction parallel to the film surface, so that the transmittance of an infrared band is improved, the reflectivity of the infrared band is reduced, and the whole sapphire material has smaller absorption and scattering characteristics. Meanwhile, the total content of oxygen and nitrogen is increased, so that the SiO from inside to outside_xN_yThe content of silicon element in the thin film layer is gradually reduced, thereby leading to the reduction of Si-Si bonds and the increase of Si-N and Si-O, and further leading to SiO_xN_yThe film layer is more stable and compact from inside to outside, the bonding strength and stability of the film are further ensured, and the abrasion resistance of the film is improved.

A preparation method of an anti-reflection film for a sapphire substrate is characterized by comprising the following steps: firstly, cleaning a sapphire material and a target material to remove surface impurities; then SiO is carried out by adopting non-equilibrium magnetron sputtering equipment₂Deposition and introduction of thin film layerThe gas source is oxygen and argon; redepositing SiO_xN_yThe thin film layer is filled with argon, oxygen and nitrogen as gas sources, and the first SiO is deposited in sequence by adjusting the gas flow rate of the nitrogen, the oxygen and the argon_xN_yThin film layer, second SiO_xN_yThin film layer, third SiO_xN_yThin film layer and fourth SiO_xN_yA thin film layer; and obtaining the anti-reflection film.

Further optimization, the specific steps of the cleaning are as follows: firstly, cleaning a sapphire material by adopting absolute ethyl alcohol, then placing the cleaned sapphire material on a sample table of a vacuum chamber of non-equilibrium magnetron sputtering equipment, and taking silicon (99.99%) as a target material; the vacuum chamber was closed and evacuated to 3.0x10^-3After Pa, turning on a bias power supply, applying 750-850V direct current voltage and 90-110V bias voltage on the sapphire material, opening an air valve, continuously introducing argon gas, enabling the flow of the argon gas to be 45-55 sccm, cleaning the sapphire material for 18-22 min, and then turning off the power supply; and then turning on a target power supply, applying a current of 0.5A to carry out pre-sputtering cleaning on the target for 9-11 min, and removing surface impurities.

For further optimization, the SiO₂The deposition of the thin film layer is specifically as follows: after cleaning the substrate material, introducing oxygen, wherein the introduction amount of the oxygen is 55-65 sccm, then introducing argon, adjusting the deposition temperature to be 170-190 ℃ by using a heating device and using a high-purity Si (99.99%) target as a cathode when the air pressure of a vacuum chamber rises to 1.0-1.5 Pa, adjusting the negative bias to be 48-52V, turning on a target sputtering power supply, setting the current to be 0.6-0.8A, and depositing for 35-45 min.

For further optimization, the SiO_xN_yThe deposition of the thin film layer is specifically as follows: adjusting the pressure of an unbalanced magnetron sputtering device to be 5x10^-3Pa, introducing nitrogen, oxygen and argon; when the air pressure of a vacuum chamber rises to 1.0-1.5 Pa, taking a high-purity Si (99.99%) target as a cathode, adjusting the deposition temperature to 170-190 ℃ through a heating device, adjusting the negative bias to 48-52V, turning on a target sputtering power supply, and setting the current to 0.6-0.8A; by controlling the flow rate of nitrogen, oxygen and argon, SiO with different nitrogen content and oxygen content is deposited_xN_yA thin film layer.

For further optimization, the first SiO_xN_yThe flow rates of the nitrogen, the oxygen and the argon of the thin film layer are respectively 78-82 sccm, 8-12 sccm and 83-87 sccm, and the deposition time is 5-7 min.

For further optimization, the second SiO_xN_yThe flow rates of nitrogen, oxygen and argon of the thin film layer are respectively 68-72 sccm, 20-24 sccm and 83-87 sccm, and the deposition time is 14-18 min.

For further optimization, the third SiO_xN_yThe flow rates of the nitrogen, the oxygen and the argon of the thin film layer are respectively 58-62 sccm, 33-37 sccm and 83-87 sccm, and the deposition time is 28-34 min.

For further optimization, the fourth SiO_xN_yThe flow rates of nitrogen, oxygen and argon of the thin film layer are 8-12 sccm, 58-62 sccm and 83-87 sccm respectively, and the deposition time is 40-52 min.

The invention has the following technical effects:

the invention uses SiO₂The film layer and four layers of SiO with the atom percent of nitrogen decreasing and the atom percent of oxygen increasing sequentially_xN_yThe composite anti-reflection film composed of the thin film layer enables the refractive index to continuously change along the normal direction of the surface of the film layer and keeps unchanged in the direction parallel to the film surface, so that the transmittance of an infrared band is effectively improved, the reflectivity of the infrared band is reduced, and the whole sapphire material has smaller absorption and scattering characteristics. At the same time, by SiO₂The inherent characteristics of the thin film layer improve the bonding strength between the thin film and the substrate and reduce the internal stress between the thin film and the substrate; four-layer SiO by gradient change of atomic percent of nitrogen element and oxygen element_xN_yThe thin film layer, thereby reduce the internal stress between thin film layer and the thin film layer, improve the bonding strength between thin film layer and the thin film layer. And, four layers of SiO_xN_yThe oxygen element and the nitrogen element of the film layer are changed in percentage, so that the four film layers are more compact from inside to outside, the density of the antireflection film is increased, the stability and the firmness of the antireflection film are improved, and the antireflection film is ensured to be wear-resistant and resistantThe corrosion resistance is stronger, the service life of the film is prolonged, the application range of the film is enlarged, and the film can be applied to high-strength fields such as military photoelectric equipment and the like.

Drawings

FIG. 1 is a schematic view showing a structure of an antireflection film in an embodiment of the present invention.

Fig. 2 is a graph showing light transmittance of antireflection films before and after the coating of the sapphire material base surface in example 1 of the present invention.

Fig. 3 is a graph showing the reflectance of the antireflection film before and after the coating of the sapphire material base surface in example 1 of the present invention.

FIG. 4 is an electron microscope image of the sapphire material after being coated in example 2 of the present invention.

Fig. 5 is an SEM image of the sapphire material after being plated in example 2 of the present invention.

Wherein, 1, a sapphire material basal plane; 2. SiO 2₂A thin film layer; 3. first SiO_xN_yA thin film layer; 4. second SiO_xN_yA thin film layer; 5. third SiO_xN_yA thin film layer; 6. fourth SiO_xN_yA thin film layer.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.