High-hardness angle-insensitive color filter and preparation method thereof

Abstract

The invention provides a high-hardness angle-insensitive color filter and a preparation method thereof. The color filter comprises a hard reflecting layer and a hard modulation layer which are sequentially arranged on a substrate, wherein the hard reflecting layer is made of titanium nitride; the hard modulation layer is composed of a medium modulation layer amorphous silicon-rich silicon nitride, a metal absorption layer chromium and an anti-reflection layer silicon nitride, and the anti-reflection layer is free of absorption. According to the color filter, the medium modulation layer is used for inducing the hard reflecting layer to obtain the maximum reflectivity at the center wavelength, and the metal absorption layer can achieve broadband cut-off outside a reflection waveband, so that effective filtering and color display of a specific waveband are achieved. Absorption in different wave bands can be realized by adjusting the thickness of the hard modulation layer, so that reflection effects of various colors are realized, and optical filters of various colors are obtained; in addition, due to the fact that the refractive index of the medium modulation layer is large, the reflection spectrum of the optical filter changes little along with the incident angle.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical thin films, and particularly relates to a high-hardness angle-insensitive color filter and a preparation method thereof. Background Art

[0002] A color filter is a common band-pass filter that displays various colors by selectively transmitting or reflecting specific wavelengths in the visible light region. Generally, color filters can be classified into two categories according to the color filtering principle: optical filters and chemical filters. Traditional chemical filters are composed of dyes or pigments, and change the color of the reflected light through the selective absorption of wavelengths by specific functional groups, and have a relatively high angular tolerance. However, most of the chemical components of these chemical dyes or pigments are unstable, unable to withstand long-term irradiation by strong light, cannot be used in high-temperature environments, and require a large number of processes to form a filter pattern, and at the same time cause a great burden on the environment.

[0003] In recent years, extensive research has been conducted on nanostructured color filters combined with structural colors and developed in different aspects. However, most of the research has not considered the angular sensitivity of these color filters, which means that the spectra at different incident angles will shift. In many applications, it is required that the color filters have the same specular color within a large range of incident angles. Some microstructure-based color filters may meet the characteristics of being insensitive to angles, but considering the complex nanofabrication processes involved and the influence of azimuth angles in practical applications, their large-area preparation and application are greatly limited. Among them, compared with microstructure-based color filters, optical thin films based on interference effects do not require complex nanofabrication methods such as lithography, etching, milling, or femtosecond laser writing and have better durability. It has been shown that using high-refractive-index materials as spacer dielectrics can reduce the angular sensitivity of Fabry–Pérot cavity-based color filters. However, these thin-film-structured color filters have poor durability because the overall hardness of each film layer is not high. But in practical applications, the durability of color filters is also an issue that cannot be ignored. To resist dust, sand, moisture, acid rain, and salt spray, etc., not only their optical properties need to be considered, but also high durability (high hardness, high wear resistance, high temperature resistance, high corrosion resistance, etc.) is required. Silicon nitride (Si3N4) thin films have been widely used in the mechanical field to enhance the surface durability of workpieces and thus improve their service life due to a series of characteristics such as high hardness (up to 20 GPa), good chemical stability, excellent corrosion and oxidation resistance, and high temperature resistance. At the same time, Si3N4 thin films have excellent optical properties, with high transmittance and no absorption in the visible light range. Applied to the surface of solar panels, they can enhance the light absorption rate of solar panels and can also be used to prepare transparent and antireflective thin films. They are preferred materials for preparing high-hardness thin films. However, single silicon nitride thin films have a single color and cannot meet the requirements of rich colors for thin films.

[0004] Therefore, there is an urgent need to develop an angle-insensitive color filter with high scratch resistance and a wide color gamut with high saturation. Summary of the Invention

[0005] To solve the problems existing in the prior art, the present invention provides a high-hardness angle-insensitive color filter. The reflection spectrum of this high-hardness color filter hardly changes with the change of the incident angle, and it has good mechanical properties, high color saturation, and excellent scratch resistance. Its preparation method uses a colored thin film prepared by radio frequency magnetron sputtering technology, which can obtain red (CIE1931 color coordinates ~

[0006] (0.461, 0.264)), green (CIE1931 color coordinates ~(0.312, 0.462)), blue (CIE1931 color coordinates ~(0.165, 0.183)), etc., with a variety of different bright colors and a large color gamut range; and the preparation method is green and environmentally friendly, highly reproducible, and has a simple process, suitable for large-area and batch production.

[0007] A high-hardness angle-insensitive color filter includes a hard reflection layer and a hard modulation layer sequentially provided on a substrate. The hard reflection layer is titanium nitride; the hard modulation layer is composed of a dielectric modulation layer, a metal absorption layer, and an antireflection layer sequentially provided on the hard reflection layer, where the dielectric modulation layer is amorphous silicon-rich silicon nitride, the metal absorption layer is chromium, and the antireflection layer is silicon nitride, and incident light enters from the side of the antireflection layer.

[0008] The silicon nitride thin film can be regulated in its optical and electrical properties by doping or changing deposition conditions, and has good regulatability. Based on this, the present invention uses silicon nitride thin films with different nitrogen contents to prepare the dielectric modulation layer and the antireflection layer respectively, and because the metal absorption layer is relatively thin and the hard reflection layer is also titanium nitride with a high hardness, a high-hardness color filter can be obtained.

[0009] Among them, there is no limitation on the substrate material. The substrate can be selected from glass materials such as K9, fused quartz, and float glass, or semiconductor materials such as silicon and gallium arsenide, or plastic materials such as PET, PC, and PI, or alloy materials such as stainless steel (such as alloys of chromium, titanium, tungsten, nickel, germanium, etc.). Preferably, the substrate material is K9 or silicon.

[0010] Preferably, the refractive index of the titanium nitride of the hard reflection layer is 1.6 - 2.5. Preferably, the thickness of the hard reflection layer should be greater than or equal to 300 nm; more preferably 300 - 500 nm; even more preferably 300 - 400 nm.

[0011] Preferably, the refractive index of the silicon-rich silicon nitride of the dielectric modulation layer is 2.5 - 3.5. More preferably 2.5 - 3. Even more preferably 2.7. Preferably, the thickness of the silicon-rich silicon nitride film layer is 20 - 100 nm.

[0012] Preferably, the thickness of the chromium of the metal absorption layer is less than 100 nm; more preferably it should be less than 50 nm; even more preferably 4 - 30 nm.

[0013] Preferably, the refractive index of the silicon nitride of the antireflection layer is 1.8 - 2.1. At this refractive index, the antireflection layer has no absorption, and the refractive index is more preferably 2. Preferably, the thickness of the antireflection layer is 50 - 200 nm.

[0014] The present invention also provides a method for preparing a high-hardness angle-insensitive color filter, which mainly includes the following steps:

[0015] (1) Using radio frequency magnetron sputtering technology (vacuum coating), prepare a hard reflection layer of titanium nitride film, a dielectric modulation layer of silicon-rich silicon nitride film, and an anti-reflection layer of silicon nitride (Si3N4) film respectively, and perform refractive index and thickness fitting to determine that the refractive index of the obtained film layer is the set refractive index, and at the same time obtain the corresponding preparation process conditions and save them;

[0016] (2) On the basis of the preparation process conditions obtained in step (1), according to the requirements of the required color thin film, optimize the thickness of each layer of thin film, and design the structural parameters of the color filter that meet the requirements. Here, the optimization of the thickness of each layer of thin film and the design of the structural parameters of the color filter are realized by using existing software (such as TFCalc, Optilayer);

[0017] (3) After cleaning and drying the substrate, use radio frequency magnetron sputtering technology, and successively deposit a hard reflection layer of titanium nitride film, a dielectric modulation layer of silicon-rich silicon nitride film, a metal absorption layer of chromium film, and an anti-reflection layer of silicon nitride film on the substrate according to the preparation process conditions determined in step (1) and the structural parameters obtained in step (2) to obtain the high-hardness color filter.

[0018] In step (2), the requirements of the color filter include requirements such as angle sensitivity, bandwidth, absorption rate, reflectivity, chromaticity, and brightness.

[0019] In step (3), wipe the substrate with an ethanol-ether solution, and after cleaning, blow it dry with an air gun to deposit the corresponding film layer.

[0020] Preferably, in steps (1) and (3), when preparing the hard reflection layer of titanium nitride film, the argon flow rate is 0.5-100 sccm, the flow rate ratio of argon to nitrogen is 8:1-15:1, and the radio frequency power density of the corresponding silicon palladium is 60-140 W / mm 2 . Further preferably, when preparing the hard reflection layer of titanium nitride film, the argon flow rate is 1-10 sccm, the flow rate ratio of argon to nitrogen is 9:1-11:1, and the radio frequency power density of the corresponding silicon palladium is 80-120 W / mm 2 .

[0021] Preferably, in steps (1) and (3), when preparing the dielectric modulation layer of silicon-rich silicon nitride film, the argon flow rate is 0.5-100 sccm, the flow rate ratio of argon to nitrogen is 5:1-8:1, and the radio frequency power density of the corresponding silicon palladium is 60-200 W / mm 2As a further preference, when preparing the silicon-rich silicon nitride film of the dielectric modulation layer, the argon flow rate is 1-10 sccm, the flow rate ratio of argon to nitrogen is 6:1-7:1, and the radio frequency power density of the silicon palladium corresponding is 80-120 W / mm 2 。

[0022] As a preference, in steps (1) and (3), when preparing the anti-reflection layer silicon nitride film, the argon flow rate is 0.5-100 sccm, the flow rate ratio of argon to nitrogen is 1:1-4:1, and the radio frequency power density of the silicon palladium corresponding is 60-200 W / mm 2 As a further preference, when preparing the anti-reflection layer silicon nitride film, the argon flow rate is 1-10 sccm, the flow rate ratio of argon to nitrogen is 2:1-3:1, and the radio frequency power density of the silicon palladium corresponding is 120-160 W / mm 2 。

[0023] As a preference, in step (2), the structural parameters of the color filter include the number of film layers of the color filter, the materials of each film layer, and the thickness of each film layer.

[0024] The preparation method of the above color filter adopts radio frequency magnetron sputtering technology. The wiped and dried substrate is placed in the chamber. After evacuating, inert gas argon is introduced into the chamber. The radio frequency magnetron sputtering source is turned on, and nitrogen is introduced. The hard reflection layer and the hard modulation layer are sequentially deposited on the substrate surface; when depositing the dielectric modulation layer, by adjusting the nitrogen flow rate, deposition power, and deposition time, the nitrogen content and the film layer thickness in the dielectric modulation layer are changed, so as to prepare a color filter with good mechanical properties and high color saturation.

[0025] In the preparation method of the high-hardness angle-insensitive color filter of the present invention, since silicon-rich silicon nitride with high refractive index and high hardness is used as the spacer dielectric layer, it realizes good angle-insensitive color display in the visible light band and has very high hardness. Therefore, the color filter of the present invention can be widely applied to fields such as decoration and display.

[0026] Compared with the prior art, the beneficial effects of the present invention are:

[0027] The high-hardness angle-insensitive color filter of the present invention uses the dielectric modulation layer to induce the hard reflection layer to obtain the maximum reflectivity at the central wavelength, while the metal absorption layer can achieve wide-band cutoff outside the reflection band, so as to realize effective filtering of a specific band and color display. By adjusting the thickness of the hard modulation layer, absorption in different bands can be achieved, so as to realize the reflection effects of various colors and obtain color filters of various colors. In addition, due to the relatively large refractive index of the dielectric modulation layer, the reflection spectrum of the color filter changes very little with the incident angle.

[0028] Since the hard reflection layer of the present invention is high-hardness titanium nitride, and the dielectric modulation layer and the antireflection layer are silicon nitride with different nitrogen contents and high hardness, it has higher durability compared to the film layer structures in the prior art. In the filter sample of the present invention, only slight scratch marks exist on the surface after a 6-level Mohs hardness stroke under a 500g load, indicating that the sample has good mechanical properties.

[0029] The preparation method of the color filter of the present invention can prepare color filters of any required color according to requirements, and the filter can simultaneously have high hardness.

[0030] The high-hardness angle-insensitive color filter of the present invention has a simple structure, is easy to prepare, has a low cost, and is suitable for large-area batch production, thus greatly reducing the preparation cost of the hard angle-insensitive color filter. This makes the color filter promising for wide applications in fields such as decoration, color display, and solar cells, and contributes to the national economy, social development, and science and technology of our country. Brief Description of the Drawings

[0031] Figure 1 It is a schematic structural diagram of one of the high-hardness angle-insensitive color filters of the present invention;

[0032] Figure 2 It is the reflection spectra at different angles of the blue hard filter obtained in Example 1 of the present invention; wherein, the substrate is K9, the hard reflection layer is titanium nitride, the metal absorption layer is chromium, the dielectric regulation layer is silicon-rich silicon nitride, and the antireflection layer is silicon nitride;

[0033] Figure 3 It is the reflection spectra at different angles of the green hard filter obtained in Example 2 of the present invention; wherein, the substrate is silicon, the hard reflection layer is titanium nitride, the metal absorption layer is chromium, the dielectric regulation layer is silicon-rich silicon nitride, and the antireflection layer is silicon nitride;

[0034] Figure 4 It is the reflection spectra at different angles of the red hard filter obtained in Example 3 of the present invention; wherein, the substrate is K9, the hard reflection layer is titanium nitride, the metal absorption layer is chromium, the dielectric regulation layer is silicon-rich silicon nitride, and the antireflection layer is silicon nitride. Detailed Description of the Invention

[0035] The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings of the specification.

[0036] As Figure 1 shown, a high-hardness color filter is composed of a substrate, a hard reflection layer, a dielectric modulation layer, a metal absorption layer, and an antireflection layer. Among them, the hard reflection layer is titanium nitride, the dielectric modulation layer is silicon-rich silicon nitride, the metal absorption layer is chromium, and the antireflection layer is silicon nitride.

[0037] There is no limitation on the substrate material. Glass materials such as K9, fused quartz, and float glass can be selected. Semiconductor materials such as silicon and gallium arsenide can also be selected. Plastic materials such as PET, PC, and PI can also be selected. Alloy materials such as stainless steel (such as alloys of chromium, titanium, tungsten, nickel, germanium, etc.) can also be selected. The substrate material is preferably K9 or silicon.

[0038] In the following examples, the dielectric modulation film layer is preferably amorphous silicon-rich silicon nitride with a refractive index of 2.7; the antireflection layer is preferably silicon nitride (Si3N4) with a refractive index of 2 close to the standard stoichiometry.

[0039] A method for preparing a high-hardness color filter includes the following steps:

[0040] 1) Use radio frequency magnetron sputtering technology to prepare a single-layer titanium nitride film layer, a silicon-rich silicon nitride film layer, and a silicon nitride (Si3N4) film layer respectively, and perform refractive index and thickness fitting to determine that the refractive index of the obtained film layer is the set refractive index. At the same time, obtain the corresponding preparation process conditions and save them;

[0041] 2) Based on the preparation process conditions obtained in step 1), according to the requirements of the bandwidth, absorption rate, reflectivity, chromaticity, brightness, etc. of the required color filter, use TFCalc software to optimize the thickness of each film layer, and design a color filter film system that meets the requirements to obtain the structural parameters of the color filter including the total number of film layers (the number of film layers of the color thin film), the material of each film layer, and the thickness of each film layer;

[0042] 3) Wipe the substrate with an ethanol-ether solution and then dry it with an air gun to obtain a substrate;

[0043] 4) Use radio frequency magnetron sputtering technology, according to the preparation process conditions determined in step 1) and the structural parameters obtained in step 2), deposit a hard reflection layer (titanium nitride), a dielectric modulation layer (silicon-rich silicon nitride), a metal absorption layer (chromium), and an antireflection layer (silicon nitride) on the substrate in sequence, and finally obtain a high-hardness color filter.

[0044] In the above step 1), the process conditions for obtaining titanium nitride with a refractive index of 1.6 - 2.5 are: the argon flow rate is 5 sccm; the flow rate ratio of argon to nitrogen is 10:1; the radio frequency power density is 100 W / mm2.

[0045] The process conditions for obtaining amorphous silicon-rich silicon nitride with a refractive index of 2.7 are: the argon flow rate is 2.55 sccm; the flow rate ratio of argon to nitrogen is 6.375:1; the radio frequency power density is 100 W / mm 2 。

[0046] The process conditions for the refractive index of non-absorbing silicon nitride to be 2 are as follows: the argon flow rate is 2.55 sccm; the flow rate ratio of argon to nitrogen is 2.217:1; the power density of the radio frequency power supply is 140 W / mm 2 .

[0047] Example 1: A blue hard filter with an expected reflection bandwidth of 400 nm - 440 nm and an average reflectivity greater than 45%. The reflection spectra of the blue hard filter at different angles are as Figure 2 shown. The color coordinates are (0.165, 0.183). The corresponding substrate material is K9, and the corresponding film materials from the substrate side are titanium nitride, silicon-rich silicon nitride, chromium, and silicon nitride in sequence. The corresponding film thicknesses of each film layer are 300 nm, 33 nm, 22 nm, and 87 nm respectively.

[0048] Example 2: A green hard filter with an expected reflection bandwidth of 520 nm - 560 nm and an average reflectivity greater than 45%. The reflection spectra of the green hard filter at different angles are as Figure 3 shown. The color coordinates are (0.312, 0.462). The corresponding substrate material is silicon, and the corresponding film materials from the substrate side are titanium nitride, silicon-rich silicon nitride, chromium, and silicon nitride in sequence. The corresponding film thicknesses of each film layer are 300 nm, 51 nm, 5 nm, and 151 nm respectively.

[0049] Example 3: A red hard filter with an expected reflection bandwidth of 700 nm - 740 nm and an average reflectivity greater than 50%. The reflection spectra of the red hard filter at different angles are as Figure 4 shown. The color coordinates are (0.461, 0.264). The corresponding substrate material is K9, and the corresponding film materials from the substrate side are titanium nitride, silicon-rich silicon nitride, chromium, and silicon nitride in sequence. The corresponding film thicknesses of each film layer are 300 nm, 16 nm, 3 nm, and 147 nm respectively.

Claims

1. A high-hardness angle-insensitive color filter, characterized in that, It includes a hard reflection layer and a hard modulation layer sequentially disposed on a substrate. The hard reflection layer is titanium nitride; the hard modulation layer is composed of a dielectric modulation layer, a metal absorption layer, and an antireflection layer sequentially disposed on the hard reflection layer. Among them, the dielectric modulation layer is amorphous silicon-rich silicon nitride, the metal absorption layer is chromium, and the antireflection layer is silicon nitride. Incident light enters from the side of the antireflection layer.

2. The high-hardness angle-insensitive color filter according to claim 1, characterized in that The substrate is made of K9, fused quartz, float glass, silicon, gallium arsenide, PET, PC, PI, or stainless steel alloy material, preferably K9 or silicon.

3. A high-hardness angle-insensitive color filter according to claim 1, characterized in that The refractive index of the hard reflection layer is 1.6 - 2.5, and the thickness is greater than or equal to 300 nm, preferably 300 - 400 nm.

4. A high-hardness angle-insensitive color filter according to claim 1, characterized in that, The refractive index of the dielectric modulation layer is 2.5 - 3.5, preferably 2.7, and the thickness is 20 - 100 nm.

5. A high-hardness angle-insensitive color filter according to claim 1, characterized in that The thickness of the metal absorption layer is less than 100 nm, preferably 4 - 30 nm.

6. A high-hardness angle-insensitive color filter according to claim 1, characterized in that, The refractive index of the antireflection layer is 1.8 - 2.1, preferably 2, and the thickness is 50 - 200 nm.

7. A method for preparing the high-hardness angle-insensitive color filter according to any one of claims 1 to 6, characterized in that, It includes the following steps: (1) Use radio frequency magnetron sputtering technology to prepare a hard antireflection layer, a dielectric modulation layer, and an antireflection layer respectively, and perform refractive index and thickness fitting to determine that the refractive index of the obtained film layer is the set refractive index. At the same time, obtain the corresponding preparation process conditions and save them; (2) On the basis of the preparation process conditions obtained in step (1), according to the requirements of the required color film, optimize the thickness of each film layer, and design the structural parameters of the color filter that meet the requirements. Here, the optimization of the thickness of each film layer and the design of the structural parameters of the color filter are realized by using existing software (such as TFCalc, Optilayer); (3) After cleaning and drying the substrate, use radio frequency magnetron sputtering technology to deposit a hard reflection layer titanium nitride film, a dielectric modulation layer silicon-rich silicon nitride film, a metal absorption layer chromium film, and an antireflection layer silicon nitride film on the substrate in sequence according to the preparation process conditions determined in step (1) and the structural parameters obtained in step (2) to obtain the high-hardness color filter.

8. The preparation method of a high-hardness angle-insensitive color filter according to claim 7, characterized in that, In steps (1) and (3), when preparing the hard reflective layer, the argon flow rate is 0.5 to 100 sccm, the flow rate ratio of argon to nitrogen is 8:1 to 15:1, and the RF power density corresponding to silicon palladium is 60 to 140 W / mm 2 ; When preparing the dielectric modulation layer, the argon flow rate is 0.5 to 100 sccm, the flow rate ratio of argon to nitrogen is 5:1 to 8:1, and the corresponding radio frequency power density is 60 to 200 W / mm 2 ; When preparing the antireflection layer, the argon gas flow rate is 0.5 to 100 sccm, the flow rate ratio of argon gas to nitrogen gas is 1:1 to 4:1, and the corresponding radio frequency power density is 60 to 200 W / mm 2 .

9. The preparation method of a high-hardness angle-insensitive color filter according to claim 8, wherein, In steps (1) and (3), when preparing the hard reflection layer, the argon flow rate is 1 - 10 sccm, the flow rate ratio of argon to nitrogen is 9:1 - 11:1, and the RF power density corresponding to silicon palladium is 80 - 120 W / mm 2 ; When preparing the dielectric modulation layer, the argon flow rate is 1 to 10 sccm, the flow rate ratio of argon to nitrogen is 6:1 to 7:1, and the RF power density corresponding to silicon palladium is 80 to 120 W / mm 2 ; When preparing the antireflection layer, the argon flow rate is 1 to 10 sccm, the flow rate ratio of argon to nitrogen is 2:1 to 3:1, and the RF power density corresponding to silicon palladium is 120 to 160 W / mm 2 .

10. The preparation method of a high-hardness angle-insensitive color filter according to claim 7, characterized in that, In step (2), the structural parameters of the color filter include the number of film layers of the color filter, the materials of each film layer, and the thickness of each film layer.

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