CN111763016A

CN111763016A - Low stress film

Info

Publication number: CN111763016A
Application number: CN202010737705.7A
Authority: CN
Inventors: 周斌; 鲁晓江; 汪洋
Original assignee: Optorun Shanghai Co Ltd
Current assignee: Optorun Shanghai Co Ltd
Priority date: 2020-07-28
Filing date: 2020-07-28
Publication date: 2020-10-13

Abstract

The invention relates to the technical field of vacuum coating, in particular to a low-stress film, which is characterized in that: and a stress neutralization layer is arranged between the thin film layer and the substrate, and the stress neutralization layer is composed of two or more film layers with opposite stress types. The invention has the advantages that: the film stress of the whole film system structure is mutually counteracted and neutralized, and the deformation of the substrate is extremely small; the antireflection layer absorbs and interferes visible light through the stacking of chromium and silicon dioxide, and reduces the reflection of the film layer to the visible light, so that the transmittance of a visible light wave band is less than 0.1%, and the reflectivity is less than 1%; the film system has simple structure, low film stress and good film stability, can implement film coating by using common physical vapor deposition modes such as vacuum thermal evaporation, vacuum ion source auxiliary evaporation, magnetron sputtering and the like, has higher preparation performance and is convenient to popularize.

Description

Low stress film

Technical Field

The invention relates to the technical field of vacuum coating, in particular to a low-stress film.

Background

With the pursuit of light and thin of the whole intelligent terminal such as a mobile phone, a tablet personal computer and the like in the market and the continuous improvement of requirements of screen occupation ratio and the like, the thickness requirements of functional modules such as cover plate glass, a touch module, a display module, a camera module, a fingerprint identification module and the like on an intelligent terminal product are higher and higher; in the integrated circuit industry, most of the processes are performed on a large-diameter substrate, and then the substrate is cut and packaged into functional modules and assembled on a touch screen. For example, in order to meet the requirements of thickness, concealment and the like of some functional modules, a black protective film with low transmission and low reflection is generally required to be plated on a large-diameter ultrathin glass substrate; in order to facilitate the processing of the subsequent etching packaging process and other processes, the thickness of the black protective film needs to be more than 1um, and the large-diameter ultrathin substrate cannot be warped.

As is well known, under the existing vacuum coating technique conditions, any film can have a great influence on the substrate when being deposited on the surface of the substrate due to the problem of the internal stress of the film; thereby causing the substrate to generate very large warpage in the vacuum coating process or after coating, and even causing the glass substrate to crack; not only the optical characteristics and the thickness uniformity of the film are affected, but also the subsequent processing is difficult due to the deformation of the substrate. In order to reduce the influence of the film stress on the substrate, the influence of the film stress on the substrate is usually improved by adjusting the process parameters during film coating, but the improvement effect is very limited, and the stress of the film is difficult to reduce to below 10MPa, and experiments show that the warping degree of an ultrathin glass substrate with the diameter of 200mm and the thickness of 0.1mm exceeds 5mm after the whole surface is coated with a film with the thickness of 1um and the film stress of more than 10 MPa.

Disclosure of Invention

The present invention is directed to providing a low stress thin film, which has a stress neutralizing layer disposed between a substrate and an anti-reflective layer, and is stacked and bonded with coating materials of opposite stress types in a certain thickness ratio, so that the film stresses of the entire film structure counteract and neutralize each other, thereby reducing the deformation effect of the film stresses on the substrate.

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

the utility model provides a low stress film, includes the thin layer, the thin layer sets up on the base plate its characterized in that: and a stress neutralization layer is arranged between the thin film layer and the substrate, and the stress neutralization layer is composed of two or more film layers with opposite stress types.

The film layers with opposite stress types mean that one is a film layer with tensile stress type, and the other is a film layer with compressive stress type.

The film layer with the stress type of tensile stress is a first layer arranged on the substrate.

The film layer with the stress type of tensile stress is a chromium film.

The film layer with the stress type being compressive stress at least comprises one of silicon dioxide, titanium oxide, niobium oxide and tantalum oxide.

The thin film layer is an antireflection layer.

The antireflection layer is formed by stacking metal chromium and silicon dioxide.

The thickness of the film layer with the opposite stress type meets the requirement of stress counteracting and neutralizing.

The invention has the advantages that: (1) the membrane system has simple structure and less used materials; the structure of the film system is easy to design, the film coating of the film system can be easily realized by common physical vapor deposition modes such as conventional vacuum thermal evaporation, vacuum ion source auxiliary evaporation, magnetron sputtering and the like, and the film system is easy to popularize;

(2) the usable chromium metal and the compressive stress coating material have good firmness and corrosion resistance, and the coated film has good stability;

(3) because the extinction coefficient of the visible light area of the metal chromium is large, the film layer can simultaneously realize low transmittance and low reflectivity, the concealment of the film layer is very good, and the film layer cannot be identified by naked eyes in various environments and angles;

(4) by using the film system structure to carry out film coating, the warping problem of the substrate caused by film layer stress is solved, so that the glass substrate with the thickness of less than 0.1mm can not break in the film coating process, the warping degree after the film coating on the whole surface is very small, the processing of each subsequent process can not be influenced, and the mass production of the black protective film with the thickness of more than 1um coated on the ultrathin substrate with the diameter of more than 100mm and the thickness of less than 0.1mm is realized.

Drawings

FIG. 1 is a schematic diagram of a membrane system according to the present invention;

FIG. 2 is a graph showing the results of measurement of the spectrum and the warp of the first embodiment of the present invention;

fig. 3 is a diagram showing a spectrum and a warp measurement structure of a second example of application of the present invention.

Detailed Description

The features of the present invention and other related features are described in further detail below by way of example in conjunction with the following drawings to facilitate understanding by those skilled in the art:

as shown in fig. 1-3, the symbols 1-7 in the figures are respectively represented as: the stress-neutralizing layer comprises a substrate 1, a stress neutralizing layer 2, an antireflection layer 3, a tensile stress film layer 4, a compressive stress film layer 5, a chromium layer 6 and a silicon dioxide layer 7.

Example (b): as shown in fig. 1, the low stress thin film in the present embodiment may be disposed on a substrate 1, and the substrate 1 may refer to an ultra-thin glass substrate, especially a glass substrate with a large diameter (greater than 100mm in diameter) but a small thickness (less than 0.1mm in thickness), which is easily deformed by the film stress.

As shown in fig. 1, the low stress film in the present embodiment includes a stress neutralization layer 2 and a thin film layer, here, an antireflection layer 3, wherein the stress neutralization layer 2 is disposed between a substrate 1 and the antireflection layer 3. The antireflection layer 3 is an optical thin film layer having an antireflection effect, and the stress neutralizing layer 2 is a thin film layer for dispersing the stress of the substrate 1 itself and supporting the antireflection layer 3.

Specifically, the stress neutralization layer 2 is composed of two or more tensile stress film layers 4 and compressive stress film layers 5. The tensile stress film layer 4 serves as a first layer arranged on the surface of the substrate 1, because the substrate 1 has a compressive stress, and the tensile stress film layer 4 can provide a tensile stress opposite to the stress type of the compressive stress, and the tensile stress and the compressive stress can counteract and neutralize each other, so that the influence of the film stress of the optical film on the substrate 1 is eliminated. Then, because the tensile stress film layer 4 has tensile stress, a compressive stress layer 5 with opposite stress types is arranged above the tensile stress film layer, so that the compressive stress counteracts the neutral tensile stress; therefore, the stress dispersion of the substrate 1 is gradually realized through the plurality of tensile stress film layers 4 and compressive stress film layers 5 which are matched pairwise, and the purpose of reducing the acting force of the film layers on the substrate 1 is achieved.

At this time, the thicknesses of the tensile stress film layer 4 and the compressive stress film layer 5 and the film layer stress form a matched and adaptive relationship, so that the effect of counteracting and neutralizing the stress is ensured. That is, the tensile stress of the tensile stress film layer 4 with a certain thickness and the compressive stress of the compressive stress film layer 5 with a certain thickness can be obtained through testing or calculation, so that in order to meet the requirement of counteracting and neutralizing the stresses of the tensile stress film layer 4 and the compressive stress film layer 5, the stresses of the tensile stress film layer 4 and the compressive stress film layer 5 can be matched by adjusting the thicknesses of the two layers, and counteracting and neutralizing the stresses are realized. Meanwhile, the number of the stress neutralization layers 2 formed by the tensile stress film layers 4 and the compressive stress film layers 5 and the thickness of each layer of film also meet the requirement that the spectral influence on the antireflection film 3 is as small as possible, so that the effectiveness of the optical film is guaranteed.

As shown in fig. 1, the antireflection layer 3 is formed by stacking a chromium layer 6 and a silicon dioxide layer 7 on each other in this embodiment, the first layer in contact with the stress neutralization layer 2 is the chromium layer 6, and the silicon dioxide layer 7 as the second layer is disposed on the first chromium layer 6, so as to be stacked on each other. The number of layers of the antireflection layer 3 consisting of the chromium layer 6 and the silicon dioxide layer 7 and the thickness of each film satisfy the functional requirements.

In the embodiment, in specific implementation: the tensile stress film layer 4 can be a chromium layer; the compressive stress film layer 5 may be one of the common vacuum coating materials with compressive stress as the stress type, such as silicon dioxide, titanium oxide, niobium oxide, tantalum oxide, and the like, and is preferably a silicon dioxide layer adapted to the anti-reflection layer 3 to reduce the spectral influence of the stress neutralization layer 2 on the anti-reflection layer 3.

The total number of the stress neutralization layers 2 is 2-20; preferably 4 or 6 layers to ensure gradual dispersion of the stress of the substrate 1 and stable bonding with the anti-reflection layer 3, but the requirement of stress phase neutralization between the tensile stress film layer 4 and the compressive stress film layer 5 should be satisfied regardless of whether the total number of layers of the stress neutralization layer 2 is an odd number or an even number. When the total number of the stress neutralization layers 2 is an even number, the film design can be preferably performed by neutralizing two phases of stress between the adjacent tensile stress film layer 4 and compressive stress film layer 5. Since the first layer of the stress neutralization layers 2 in this embodiment is the tensile stress film layers 4 disposed on the substrate 1, and when the total number of the stress neutralization layers 2 is an odd number, the number of the tensile stress film layers 4 is greater than the number of the compressive stress layers 5, the sum of the tensile stresses provided by all the tensile stress film layers 4 should satisfy the requirement of being capable of being neutralized by the sum of the compressive stresses provided by all the compressive stress film layers 5.

The total number of layers of the antireflection layer 3 is 4, 6, 8 or 10, preferably 4 or 6, in order to satisfy its functional requirements, while ensuring a stable bonding with the stress-neutralizing layer 2.

The thicknesses of the antireflection layer portions of the 4-layer structure described above were as follows: the thickness of the chromium layer 6 of the first layer is 100nm-120nm, the thickness of the silicon dioxide layer 7 of the second layer is 70nm-90nm, the thickness of the chromium layer 6 of the third layer is 5nm-15nm, and the thickness of the silicon dioxide layer 7 of the fourth layer is 70nm-90 nm;

the thickness of the anti-reflection layer portion of the 6-layer structure described above was as follows: the thickness of the chromium layer 6 of the first layer is 100nm-120nm, the thickness of the silicon dioxide layer 7 of the second layer is 20nm-40nm, the thickness of the chromium layer 6 of the third layer is 10nm-30nm, the thickness of the silicon dioxide layer 7 of the fourth layer is 60nm-80nm, the thickness of the chromium layer 6 of the fifth layer is 5nm-15nm, and the thickness of the silicon dioxide layer 7 of the sixth layer is 70nm-100 nm;

when the embodiment is applied specifically, the embodiment includes the following two application examples:

1) a black protective film with the total thickness of about 3um is required to be plated on an ultrathin glass substrate with the diameter of 200mm and the thickness of 0.07 mm; the transmittance in the wavelength range of 380nm-1100nm is required to be less than 0.1%, the reflectivity in the wavelength range of 380-780mm is required to be less than 1%, and the substrate warpage after coating is less than 0.5 mm.

Firstly, plating a 100 nm-thick chromium single-layer film and a 100 nm-thick silicon dioxide single-layer film on a glass test piece in a crystal control mode, completing single-layer film stress measurement, and determining the stress of the chromium film layer to be 268Mpa and the stress type of the film layer to be tensile stress; the stress of the silicon dioxide layer is-182 Ma, and the stress type of the film layer is compressive stress.

And then dividing the stress absolute value of the chromium film layer by the stress absolute value of the silicon dioxide film layer to calculate that the ratio of the total thickness of the chromium film layer to the total thickness of the silicon dioxide layer in the film system structure is about 1:1.47 approximately.

Next, the reaction is performed in the following steps of 1:1.47 total thickness proportional relation of chromium and silicon dioxide, and designing 12-layer film system structure of 6 layers of stress neutralization layers and 6 layers of antireflection layers, wherein the specific film system structure is as follows:

substrate I360 nm chromium/530 nm silicon dioxide/120 nm chromium/34.8 nm silicon dioxide/19.3 nm chromium/72.4 nm silicon dioxide/6 nm chromium/85.7 nm silicon dioxide I AIR.

In the film system structure, the front 6 layers are parts of the stress neutralization layer 2, and the rear 6 layers are parts of the antireflection layer 3; the total thickness is about 3 um.

Finally, a crystal control mode is adopted on vacuum coating equipment equipped with a crystal oscillator for monitoring, the whole-surface coating of the 12-layer film system structure is completed on an ultrathin substrate with the diameter of 200mm and the thickness of 0.07mm, and the transmittance and reflectivity spectrum test, the substrate warpage test and related test methods all use conventional test methods in the field; the test results are shown in FIG. 2:

from the results, the black film of the application example has 0.001% transmittance in the wavelength range of 380nm-1100nm and 0.43% reflectance in the wavelength range of 380-780mm, and the spectrum is qualified; after film coating, the warpage of the substrate is 0.118mm, the warpage is very small, and the warpage of the substrate cannot be seen by naked eyes.

2) A black protective film with the total thickness of about 1.5um is required to be plated on an ultrathin glass substrate with the diameter of 200mm and the thickness of 0.07 mm; the transmittance in the wavelength range of 380nm-1100nm is required to be less than 0.1 percent, the reflectivity in the wavelength range of 380-780mm is required to be less than 1 percent, and the substrate warpage after coating is less than 0.5 mm;

firstly, plating a 100 nm-thick chromium single-layer film and a 100 nm-thick titanium oxide single-layer film on a glass test piece in a crystal control mode, completing single-layer film stress measurement, and determining the stress of the chromium film layer to be 268Mpa and the film layer stress type to be tensile stress; the stress of the titanium oxide film layer is-153 Ma, and the stress type of the film layer is compressive stress.

And then dividing the stress absolute value of the chromium film layer by the stress absolute value of the titanium oxide film layer to calculate that the ratio of the total thickness of the chromium film layer to the total thickness of the titanium oxide film layer in the film system structure is about 1:1.75 approximately.

Next, the reaction is performed in the following steps of 1:1.75 the total thickness proportional relationship of chromium and titanium oxide, and designing 8-layer film system structure of 4 layers of stress neutralization layers and 4 layers of antireflection layers, wherein the specific film system structure is as follows:

substrate I220 nm chromium/385 nm titanium oxide/120 nm chromium/90.8 nm silicon dioxide/6.8 nm chromium/84.1 nm silicon dioxide I AIR.

In the film system structure, the front 4 layers are parts of the stress neutralization layer 2, and the rear 4 layers are parts of the antireflection layer 3; the total thickness is about 1.5 um.

Finally, a crystal control mode is adopted on vacuum coating equipment equipped with a crystal oscillator for monitoring, the whole-surface coating of the 8-layer film system structure is completed on an ultrathin substrate with the diameter of 200mm and the thickness of 0.07mm, and the transmittance and reflectivity spectrum test, the substrate warpage test and related test methods all use conventional test methods in the field; the test results are shown in FIG. 3:

from the results, the black film of the application example has a transmittance of 0.0012% in the wavelength range of 380nm-1100nm and a reflectance of 0.17% in the wavelength range of 380-780mm, and the spectrum is qualified; after the film is coated, the warpage of the substrate is 0.168mm, the warpage is very small, and the warpage deformation of the substrate cannot be seen by naked eyes.

Although the conception and the embodiments of the present invention have been described in detail with reference to the drawings, those skilled in the art will recognize that various changes and modifications can be made therein without departing from the scope of the appended claims, and therefore, they are not to be considered repeated herein.

Claims

1. The utility model provides a low stress film, includes the thin layer, the thin layer sets up on the base plate its characterized in that: and a stress neutralization layer is arranged between the thin film layer and the substrate, and the stress neutralization layer is composed of two or more film layers with opposite stress types.

2. A low stress film according to claim 1, wherein: the film layers with opposite stress types mean that one is a film layer with tensile stress type, and the other is a film layer with compressive stress type.

3. A low stress film according to claim 2, wherein: the film layer with the stress type of tensile stress is a first layer arranged on the substrate.

4. A low stress film according to claim 2 or 3, wherein: the film layer with the stress type of tensile stress is a chromium film.

5. A low stress film according to claim 2, wherein: the film layer with the stress type being compressive stress at least comprises one of silicon dioxide, titanium oxide, niobium oxide and tantalum oxide.

6. A low stress film according to claim 1, wherein: the thin film layer is an antireflection layer.

7. A low stress film according to claim 6, wherein: the antireflection layer is formed by stacking metal chromium and silicon dioxide.

8. A low stress film according to claim 1, wherein: the thickness of the film layer with the opposite stress type meets the requirement of stress counteracting and neutralizing.