TFT (Thin Film Transistor) alkali-free glass substrate capable of inhibiting microcrack propagation and having high interface bonding energy and preparation method of TFT alkali-free glass substrate

Abstract

The invention discloses a TFT (Thin Film Transistor) alkali-free glass substrate capable of inhibiting microcrack propagation and having high interface bonding energy and a preparation method of the TFT alkali-free glass substrate, and relates to the technical field of glass. Through the unique glass formula design, the ionic radius gradient ratio of alkaline earth metal and the field intensity synergistic effect are utilized, so that the crosslinking degree of a glass network is remarkably improved, the interface bonding energy is improved, the bonding performance of a glass substrate and other functional layers is effectively improved, the risk of crack generation is reduced, and the service life of the glass substrate is prolonged. And the reliability and the service life of the product are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of glass, and particularly to a TFT alkali-free glass substrate that inhibits the propagation of microcracks and has a high interfacial binding energy, and a preparation method thereof. Background Art

[0002] With the continuous development of display technology, TFT display devices have occupied an important position in the field of flat panel displays. As a key component of TFT display devices, the performance of alkali-free glass substrates directly affects the quality and stability of display panels. However, in traditional alkali-free glass (SiO2-Al2O3-B2O3 system), the proportion design of alkaline earth metals (MgO, CaO, SrO, BaO) is unreasonable, resulting in the critical stress intensity factor for crack propagation (KIC) being lower than 0.65 MPa·m 1 / 2 . Existing technologies such as a quality control device, quality control system and method for a TFT substrate glass disclosed in Chinese invention patent CN110597198B optimize process parameters through the quality control system, but do not solve the problem of the intrinsic crack resistance of the material; Chinese invention patent CN118908565A discloses a preparation process for a high-generation TFT-LCD glass substrate. Although the float process is improved, it still relies on traditional components and is prone to microcrack propagation problems during long-term use, resulting in a decline in the performance of display panels.

[0003] In addition, the interfacial binding energy between the glass substrate and the thin film layer is also a key factor affecting the stability of the display panel. Insufficient interfacial binding energy (<2.0 J / m 2 ) will result in a high risk of delamination failure in the process of high-generation lines (G8.5+). Therefore, it is of great significance to develop a TFT alkali-free glass substrate that can inhibit the propagation of microcracks and has a high interfacial binding energy. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: to overcome the deficiencies of the prior art, and provide a TFT alkali-free glass substrate that inhibits the propagation of microcracks and has a high interfacial binding energy, and a preparation method thereof. Through a unique glass formulation design, by using the ion radius gradient ratio and field strength synergy effect of alkaline earth metals, the crosslinking degree of the glass network is significantly improved, the interfacial binding energy is increased, the binding performance between the glass substrate and other functional layers is effectively improved, the risk of crack generation is reduced, and the reliability and service life of the product are improved.

[0005] The technical solution of the present invention is as follows:

[0006] On the one hand, the present invention provides a TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition, comprising the following components in mass percentage: SiO2 60-65wt.%, Al2O3 15-18wt.%, B2O3 5-7wt.%, alkaline earth metal oxides 10-13%, Y2O3 0.5-1.5wt.%, La2O3 0.5-1.5wt.%, ZnO 1-3wt.%, ZrO2 1-3wt.%, AlN 1-3wt.% and clarifier 0.5-1.5wt.%; wherein the alkaline earth metal oxides include MgO, SrO, CaO and BaO, and the mass ratio of MgO to SrO is (2.5-3.5):2, the mass ratio of CaO to BaO is (3.5-4.5):1, and the mass ratio of MgO to BaO is (4.5-5.5):1.

[0007] Preferably, the clarifier is SnO2.

[0008] In the present invention, SiO2, as a glass network former, gives the glass good chemical stability and mechanical strength; Al2O3 can improve the thermal stability and chemical durability of the glass; B2O3 can reduce the melting temperature of the glass and improve the forming properties of the glass. The alkaline earth metal field strength synergistic effect can optimize the glass network crosslinking density and reduce the non-bridging oxygen ratio.

[0009] 1) Ionic radius gradient matching and network densification

[0010] Ion size complementary filling: Mg 2+ (radius ) and Sr 2+ (radius ) can form a size gradient, small radius Mg 2+ The glass network gap is filled preferentially, while the large radius Sr 2+ Occupy skeleton nodes and reduce structural defects.

[0011] Ca 2+ (radius ) and Ba 2+ (radius ) to further balance the network density: Ca 2+ Strengthen short-term orderliness, Ba 2 + Suppressing lattice distortion greatly improves the uniformity of the overall structure.

[0012] Local stress field regulation: Mg 2+ With Sr 2+ The difference in ionic radius A micro-area compressive stress field is formed in the glass, forcing the microcrack propagation path to deflect to a non-linear direction. The crack propagation needs to overcome an additional stress energy barrier (about 0.2-0.5 J / m2 ), significantly improving the fracture toughness.

[0013] 2) Electric field strength synergy effect and network crosslinking strengthening

[0014] Charge distribution optimization: High electric field strength Mg 2+ (Z / r 2 = 2.78) acts as a network former, anchoring [SiO4] tetrahedrons through strong electrostatic forces, while low electric field strength Ba 2+ (Z / r 2 = 1.48) acts as a network modifier, releasing local stress, and the two work together to increase the crosslinking density. Experiments show that when the mass ratio of MgO to BaO is (4.5 - 5.5):1, the proportion of non-bridging oxygen in the glass network is reduced to less than 12%, and the interfacial binding energy is increased to more than 2.5 J / m 2 above.

[0015] Dynamic coordination effect: Mg 2+ tends to form [MgO6] octahedrons, which are connected to [SiO4] by sharing vertices, while the coordination number of Ba 2+ (CN = 8 - 12) can be dynamically adjusted to promote ion migration during the high-temperature melting stage, forming a more stable three-dimensional network structure.

[0016] 3) Total content optimization and thermodynamic stability

[0017] Thermal expansion coefficient matching: When the total content of alkaline earth metal oxides is 10 - 13%, the difference in thermal expansion coefficients (Δα) between the glass substrate and the ITO layer can be ≤ 0.5×10 -6 / °C, reducing the initiation of microcracks caused by interfacial thermal stress.

[0018] Through testing, this content range increases the critical temperature of phase separation of the glass to above 950°C, suppressing the risk of high-temperature crystallization.

[0019] Melt viscosity regulation: When the total content of alkaline earth metal oxides is less than 10%, the viscosity of the glass melt is too low (<10 2 Pa·s), and bubble defects are likely to occur; when it is higher than 13%, the viscosity is too high (>10 4 Pa·s), resulting in uneven forming stress.

[0020] In the present invention, rare earth element ions have a relatively large ionic radius, can fill the interstitial spaces of the glass network, enhance the stability of the network structure, and improve the optical and chemical stability of the glass. Y 3+ and La 3+ can stabilize the tetragonal phase of ZrO2, suppress high-temperature phase transformation, and at the same time form Y-O-Si bonds with SiO2, enhancing the chemical bonding between the composite film and the glass.

[0021] Among transition metal oxides, ZnO can reduce the thermal expansion coefficient of glass and improve its chemical stability; ZrO2 has a high refractive index and chemical stability, can refine the glass grains, and improve the mechanical strength and thermal shock resistance of the glass.

[0022] In the present invention, rare earth elements and transition metal oxides participate in the formation of the network structure, enhancing the interaction between the network and other functional layers.

[0023] At high temperatures, AIN decomposes into Al 3+ and N 3- ,N 3- combines with the free oxygen in the glass, inhibits the generation of oxygen vacancies, improves the thermal stability, and makes the critical temperature of phase separation ≥ 1050 °C. Al 3+ can participate in the formation of the glass network structure, enhancing the network strength. AlN inhibits the generation of oxygen vacancies and improves the thermal stability, and they jointly inhibit the propagation of microcracks.

[0024] The principle of action of the clarifying agent is to decompose and generate gas at high temperatures. These gases form bubbles in the glass melt, and during the rising process, they adsorb the tiny bubbles in the glass melt, thereby promoting the discharge of bubbles in the glass melt and improving the transparency and quality of the glass. Taking SnO2 of the present invention as an example, at high temperatures, SnO2 will undergo a partial reduction reaction, releasing oxygen. The bubbles formed by oxygen can carry other small bubbles in the glass melt to float to the surface and be discharged.

[0025] On the other hand, the present invention provides a method for preparing the above-mentioned TFT alkali-free glass substrate that inhibits the propagation of microcracks and has a high interfacial binding energy, including the following steps:

[0026] S1 Raw material mixing: Mix the raw materials of each component evenly to obtain a mixture;

[0027] S2 Melting: Put the mixture into a furnace for melting to obtain a glass melt;

[0028] S3 Overflow forming: Overflow the glass melt through an overflow tank onto a forming device to form the glass melt into a glass substrate;

[0029] S4 Annealing: The glass substrate enters an annealing furnace for annealing treatment;

[0030] S5 Deposition: After the glass substrate is formed, use physical vapor deposition (PVD) or chemical vapor deposition (CVD) methods to deposit a SiO2 - Al2O3 - ZrO2 composite film on the surface of the glass substrate, where the SiO2 content is 50 - 70 wt.%, the Al2O3 content is 20 - 30 wt.%, and the ZrO2 content is 10 - 20 wt.%;

[0031] S6 Heat treatment: The glass substrate with the deposited SiO2-Al2O3-ZrO2 composite film is placed in a heat treatment furnace for heat treatment to obtain a TFT alkali-free glass substrate that inhibits the propagation of microcracks and has a high interfacial binding energy.

[0032] In the SiO2-Al2O3-ZrO2 composite film, SiO2, as the main component of the glass substrate, forms continuous chemical bonds (Si-O-Si) with the SiO2 in the substrate, reducing the interfacial energy; at the same time, it binds to the SiO2 in the glass substrate through covalent bonds, reducing interfacial defects.

[0033] In Al2O3, Al 3+ can fill the gaps in the glass network and form [AlO4] tetrahedrons with alkaline earth metals (such as Mg 2+ , Ca 2+ ) to enhance the crosslinking density. The high melting point (2050 °C) of Al2O3 improves the high-temperature stability of the composite film and prevents delamination during the process.

[0034] ZrO2 undergoes a tetragonal phase → monoclinic phase transformation (volume expansion of 3-5%) under stress, generating a compressive stress field that forces the crack to deflect or close. Zr 4+ forms Zr-O-M (M = alkaline earth metal) bonds with the alkaline earth metals in the glass (such as Sr 2+ , Ba 2+ ) to strengthen the interfacial binding.

[0035] At the same time, the SiO2-Al2O3-ZrO2 composite film of the present invention also has a synergistic effect with the glass substrate components:

[0036] Migration of alkaline earth metals: During the heat treatment process, Mg 2+ , Ca 2+ in the glass diffuse into the composite film and form spinel (MgAl2O4) or calcium aluminate (CaAl2O4) with Al2O3, further enhancing the interfacial binding energy (up to 2.6 J / m 2 ).

[0037] The heat treatment process promotes the following reactions to occur:

[0038] ZrO2 + MgO → MgZrO3 (enhancing interfacial toughness);

[0039] Al2O3 + CaO → CaAl2O4 (reducing interfacial stress).

[0040] Preferably, in step S1, the particle size of the raw materials is 80-200 mesh.

[0041] Preferably, in step S2, the melting temperature is 1550-1650 °C, the melting time is 4-6 h, and the glass liquid is continuously stirred at a rate of 60-100 r / min during the melting process.

[0042] Preferably, in step S3, the overflow tank temperature is 1200 - 1300 °C, and the forming speed is 0.5 - 1.5 m / min.

[0043] Preferably, in step S4, during annealing, first hold at 670 - 690 °C for 1 - 2 h, then cool at a rate of 1 - 3 °C / min to 640 - 660 °C, hold for another 0.5 - 1.5 h, and finally cool in the furnace to room temperature.

[0044] Preferably, in step S5, the thickness of the SiO2 - Al2O3 - ZrO2 composite film is 50 - 200 nm.

[0045] Preferably, in step S6, the heat treatment temperature is 700 - 800 °C, the heat treatment time is 1 - 3 h, then cool at a rate of 1 - 3 °C / min to 650 - 670 °C, hold for 1 - 2 h, and finally cool in the furnace to room temperature.

[0046] Compared with the prior art, the present invention has the following beneficial effects:

[0047] 1. Through the unique glass formulation design of the present invention, by utilizing the ionic radius gradient ratio and field strength synergistic effect of alkaline earth metals, the cross - linking degree of the glass network is significantly improved, the interfacial binding energy is increased, the binding performance between the glass substrate and other functional layers is effectively improved, the risk of crack generation is reduced, and the reliability and service life of the product are enhanced. At the same time, the glass substrate has higher strength and stability, and can better meet the usage requirements of TFT - LCDs in complex environments. Meanwhile, by reasonably adding fining agents, the transparency and quality of the glass are effectively improved.

[0048] 2. By depositing the SiO2 - Al2O3 - ZrO2 composite film on the formed glass substrate and performing heat treatment, a crack passivation structure can be formed, effectively eliminating the internal stress of the glass and improving the comprehensive performance of the glass. Detailed implementation mode

[0049] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.

[0050] Example 1

[0051] The TFT alkali-free glass substrate for suppressing microcrack propagation and having a high interfacial binding energy in this embodiment comprises components in the following mass percentages: 60% of SiO2, 15% of Al2O3, 5% of B2O3, 4.8% of MgO, 3.2% of SrO, 4% of CaO, 0.96% of BaO, 0.5% of Y2O3, 0.54% of La2O3, 1% of ZnO, 2% of ZrO2, 2% of AlN, and 1% of SnO2.

[0052] The preparation method of the TFT alkali-free glass substrate for suppressing microcrack propagation and having a high interfacial binding energy in this embodiment comprises the following steps:

[0053] S1 Raw material mixing: Control the particle sizes of the raw materials of each component within 80 - 200 mesh and mix them evenly to obtain a mixed material;

[0054] S2 Melting: Put the mixed material into a furnace for melting, control the melting temperature at 1600 °C, and the melting time at 5 h to fully melt the raw materials to form a uniform glass melt; during the melting process, continuously stir the glass melt at a rate of 80 r / min to promote the full melting and uniform mixing of the raw materials, and further improve the uniformity of the glass melt;

[0055] S3 Overflow forming: Overflow the glass melt onto a forming device through an overflow trough, control the temperature of the overflow trough at 1250 °C to ensure that the glass melt has appropriate fluidity; the glass melt flows downward along both sides of the overflow trough under the action of gravity, converges and merges at the bottom to form a glass substrate with a uniform thickness; control the forming speed at 1 m / min;

[0056] S4 Annealing: The glass substrate enters an annealing furnace for annealing treatment. First, keep it at 680 °C for 1 h, then cool it at a rate of 2 °C / min to 650 °C, keep it at this temperature for 1 h, and finally cool it to room temperature with the furnace;

[0057] S5 Deposition: After the glass substrate is formed, use physical vapor deposition (PVD) method to deposit a SiO2 - Al2O3 - ZrO2 composite film with a thickness of 100 nm on the surface of the glass substrate, where the content of SiO2 is 60 wt.%, the content of Al2O3 is 25 wt.%, and the content of ZrO2 is 15 wt.%; the specific process is as follows: under a vacuum environment of 10 -4 Pa, place the targets containing SiO2, Al2O3, and ZrO2 in the sputtering source, use an ion beam (ion beam energy is 500 eV) to bombard the targets, so that the atoms or molecules in the targets are sputtered out and deposited on the surface of the glass substrate to form a composite film; during the deposition process, control the sputtering power at 100 W, the sputtering time at 30 min, and the distance between the target and the substrate at 5 cm;

[0058] S6 Heat treatment: Place the glass substrate with the deposited SiO2 - Al2O3 - ZrO2 composite film into a heat treatment furnace. Heat it at 750 °C for 2 h, then cool it at a rate of 2 °C / min to 660 °C, keep it warm for 1.5 h, and finally cool it to room temperature with the furnace. Precisely control the cooling rate to ensure the full migration of alkaline earth metal ions, redistribute the ions at the interface, form an interface transition layer, reduce the glass stress, form a crack passivation structure, and obtain a TFT alkali - free glass substrate that inhibits the propagation of micro - cracks and has a high interface bonding energy.

[0059] Perform performance tests on the TFT alkali - free glass substrate prepared in this example:

[0060] Interface bonding energy: Tested by the scratch method, and its interface bonding energy is 2.6 J / m 2 .

[0061] Transparency: Tested by a spectrophotometer, and the average transmittance reaches 92% in the visible light range (400 - 760 nm).

[0062] Example 2

[0063] The TFT alkali - free glass substrate with inhibited micro - crack propagation and high interface bonding energy in this example includes the following components by mass percentage: SiO2 60%, Al2O3 16.7%, B2O3 5.5%, MgO 4.5%, SrO 2.8%, CaO 3.8%, BaO 1%, Y2O3 0.5%, La2O3 1.5%, ZnO 1%, ZrO2 1.2%, AlN 1%, and SnO2 0.5%.

[0064] The preparation method of the TFT alkali - free glass substrate with inhibited micro - crack propagation and high interface bonding energy in this example includes the following steps:

[0065] S1 Raw material mixing: Control the particle size of the raw materials of each component within 80 - 200 mesh and mix them evenly to obtain a mixed material;

[0066] S2 Melting: Put the mixed material into a furnace for melting, control the melting temperature at 1550 °C, and the melting time is 6 h to fully melt the raw materials to form a uniform glass liquid; during the melting process, continuously stir the glass liquid at a rate of 60 r / min to promote the full melting and uniform mixing of the raw materials, and further improve the uniformity of the glass liquid;

[0067] S3 Overflow forming: Let the glass liquid overflow through an overflow trough onto a forming device, control the temperature of the overflow trough at 1200 °C to ensure that the glass liquid has appropriate fluidity; the glass liquid flows downward along both sides of the overflow trough under the action of gravity, converges and merges at the bottom to form a glass substrate with a uniform thickness; control the forming speed at 0.5 m / min;

[0068] S4 Annealing: The glass substrate enters the annealing furnace for annealing treatment. It is first held at 670 °C for 2 h, then cooled at a rate of 1 °C / min to 640 °C, held for another 0.5 h, and finally cooled to room temperature in the furnace.

[0069] S5 Deposition: After the glass substrate is formed, a SiO2 - Al2O3 - ZrO2 composite film with a thickness of 200 nm is deposited on the surface of the glass substrate by physical vapor deposition (PVD). Among them, the SiO2 content is 50 wt.%, the Al2O3 content is 20 wt.%, and the ZrO2 content is 10 wt.%. The specific process is as follows: under a vacuum of 10 -6 Pa, the target containing SiO2, Al2O3, and ZrO2 is placed in the sputtering source, and the target is bombarded by an ion beam (ion beam energy is 1000 eV) to sputter out atoms or molecules in the target and deposit them on the surface of the glass substrate to form a composite film. During the deposition process, the sputtering power is controlled at 300 W, the sputtering time is 90 min, and the distance between the target and the substrate is 10 cm.

[0070] S6 Heat Treatment: The glass substrate deposited with the SiO2 - Al2O3 - ZrO2 composite film is placed in a heat treatment furnace, heat - treated at 700 °C for 3 h, then cooled at a rate of 1 °C / min to 650 °C, held for 1 h, and finally cooled to room temperature in the furnace. The cooling rate is precisely controlled to ensure the full migration of alkaline earth metal ions, redistribute the ions at the interface, form an interface transition layer, reduce the glass stress, form a crack passivation structure, and obtain a TFT - free alkali glass substrate that inhibits the propagation of micro - cracks and has a high interface bonding energy.

[0071] Perform performance tests on the TFT - free alkali glass substrate prepared in this example:

[0072] Interface Bonding Energy: Measured by the scratch method, the interface bonding energy is 2.5 J / m 2 。

[0073] Transparency: Tested by a spectrophotometer, the average transmittance reaches 91% in the visible light range (400 - 760 nm).

[0074] Example 3

[0075] The TFT - free alkali glass substrate with inhibited micro - crack propagation and high interface bonding energy in this example includes the following components in mass percentages: SiO2 60%, Al2O3 15%, B2O3 5%, MgO 4.8%, SrO 3.2%, CaO 4%, BaO 1%, Y2O3 1%, La2O3 1%, ZnO 2%, ZrO2 1%, AlN 1%, and SnO2 1%.

[0076] The preparation method of the TFT alkali-free glass substrate for suppressing the propagation of microcracks and having a high interfacial binding energy in this embodiment includes the following steps:

[0077] S1 Raw material mixing: Control the particle size of the raw materials of each component to be 80 - 200 mesh and mix them evenly to obtain a mixed material;

[0078] S2 Melting: Put the mixed material into a furnace for melting, control the melting temperature at 1650 °C, and the melting time is 4 h to fully melt the raw materials to form a uniform glass liquid; during the melting process, continuously stir the glass liquid at a rate of 100 r / min to promote the full melting and uniform mixing of the raw materials, and further improve the uniformity of the glass liquid;

[0079] S3 Overflow forming: Overflow the glass liquid onto the forming device through an overflow tank, control the temperature of the overflow tank at 1300 °C to ensure that the glass liquid has appropriate fluidity; the glass liquid flows downward along both sides of the overflow tank under the action of gravity, converges and merges at the bottom to form a glass substrate with a uniform thickness; control the forming speed at 1.5 m / min;

[0080] S4 Annealing: The glass substrate enters an annealing furnace for annealing treatment. First, keep it at 690 °C for 1 h, then cool it at a rate of 3 °C / min to 660 °C, then keep it at this temperature for 1.5 h, and finally cool it to room temperature with the furnace;

[0081] S5 Deposition: After the glass substrate is formed, use physical vapor deposition (PVD) method to deposit a SiO2 - Al2O3 - ZrO2 composite film with a thickness of 100 nm on the surface of the glass substrate, where the SiO2 content is 70 wt.%, the Al2O3 content is 30 wt.%, and the ZrO2 content is 20 wt.%; the specific process is as follows: at 10 -5 Pa in a vacuum environment, place the targets containing SiO2, Al2O3, and ZrO2 in the sputtering source, use an ion beam (ion beam energy is 800 eV) to bombard the targets, so that the atoms or molecules in the targets are sputtered out and deposited on the surface of the glass substrate to form a composite film; during the deposition process, control the sputtering power at 200 W, the sputtering time at 60 min, and the distance between the target and the substrate at 8 cm;

[0082] S6 Heat treatment: Put the glass substrate deposited with the SiO2 - Al2O3 - ZrO2 composite film into a heat treatment furnace, heat-treat it at 800 °C for 1 h, then cool it at a rate of 3 °C / min to 670 °C, then keep it at this temperature for 2 h, and finally cool it to room temperature with the furnace. Precisely control the cooling rate to ensure the full migration of alkaline earth metal ions, redistribute the ions at the interface, form an interfacial transition layer, reduce the glass stress, and form a crack passivation structure to obtain the TFT alkali-free glass substrate for suppressing the propagation of microcracks and having a high interfacial binding energy.

[0083] Perform performance tests on the TFT alkali-free glass substrate prepared in this embodiment:

[0084] Interface binding energy: Tested by the scratch method, and the measured interface binding energy is 2.6 J / m 2 .

[0085] Transparency: Tested by a spectrophotometer, and the average transmittance reaches 92% in the visible light range (400 - 760 nm).

[0086] Comparative Example 1

[0087] The TFT alkali-free glass substrate of Comparative Example 1 includes the following components by mass percentage: SiO2 65%, Al2O3 18%, B2O3 7%, MgO 4%, SrO 2%, CaO 3%, BaO 1%.

[0088] The difference between the preparation method of the TFT alkali-free glass substrate of Comparative Example 1 and that of Example 1 is that: in step S2, the melting temperature is 1500 °C and the melting time is 3 h; and steps S5 and S6 are not carried out.

[0089] Perform performance tests on the TFT alkali-free glass substrate prepared in Comparative Example 1:

[0090] Interface binding energy: Tested by the scratch method, and the measured interface binding energy is 1.8 J / m 2 .

[0091] Transparency: Tested by a spectrophotometer, and the average transmittance reaches 85% in the visible light range (400 - 760 nm).

[0092] In the traditional alkali-free glass substrate prepared in Comparative Example 1, the proportion configuration of alkaline earth metals cannot exert the synergistic effect of ionic radius gradient and field strength, the network crosslinking degree is low, and the interface binding energy is insufficient; at the same time, components such as rare earth elements, transition metal oxides, and AlN are not added, resulting in poor optical properties and structural stability of the glass and low transparency. Finally, during the preparation process, the SiO2 - Al2O3 - ZrO2 composite film is not deposited and heat-treated, and the crack passivation structure cannot be formed, and the internal stress of the glass is not effectively eliminated, affecting the comprehensive performance.

[0093] Comparative Example 2

[0094] The TFT alkali-free glass substrate of Comparative Example 2 includes the following components by mass percentage: SiO2 65%, Al2O3 16%, B2O3 6%, MgO 4.8%, SrO 3.2%, CaO 4%, BaO 1%.

[0095] The difference between the preparation method of the TFT alkali-free glass substrate of Comparative Example 2 and that of Example 1 is that: steps S5 and S6 are not carried out.

[0096] Perform performance tests on the TFT alkali-free glass substrate prepared in Comparative Example 2:

[0097] Interface binding energy: Tested by the scratch method, and the measured interface binding energy is 2.2 J / m 2 .

[0098] Transparency: Tested by a spectrophotometer, and the average transmittance reaches 88% in the visible light range (400 - 760 nm).

[0099] Although Comparative Example 2 improved the network crosslinking degree to a certain extent by optimizing the proportion of alkaline earth metals, resulting in an increase in the interface binding energy, but without adding components such as rare earth elements, transition metal oxides, AlN, and clarifying agents, the improvement of the optical properties and stability of the glass is limited, and the transparency is relatively low. In addition, Comparative Example 2 did not deposit the SiO2 - Al2O3 - ZrO2 composite film and perform heat treatment, so the crack passivation structure could not be formed, and the internal stress of the glass was not effectively eliminated, affecting the comprehensive performance.

[0100] Comparative Example 3

[0101] The TFT alkali-free glass substrate of Comparative Example 3 includes the following components in mass percentages: SiO2 60%, Al2O3 15%, B2O3 5%, MgO 4%, SrO 4%, CaO 3%, BaO 2%, Y2O3 0.5%, La2O3 0.5%, ZnO 1%, ZrO2 2%, AlN 2%, and SnO2 1%.

[0102] The preparation method of the TFT alkali-free glass substrate of Comparative Example 3 is the same as that of Example 1.

[0103] Perform performance tests on the TFT alkali-free glass substrate prepared in Comparative Example 3:

[0104] Interface binding energy: Tested by the scratch method, and the measured interface binding energy is 2.3 J / m 2 .

[0105] Transparency: Tested by a spectrophotometer, and the average transmittance reaches 90% in the visible light range (400 - 760 nm).

[0106] Since the mass ratio between MgO, SrO, CaO, and BaO in Comparative Example 3 is not appropriate, an ideal ion radius gradient cannot be formed, and the field strength synergistic effect cannot be effectively exerted. This leads to a decrease in the network crosslinking degree of the glass and an increase in the proportion of non-bridging oxygen, thereby reducing the interface binding energy. At the same time, the structural stability deteriorates, affecting the optical properties of the glass and resulting in a decrease in transparency.

[0107] Comparative Example 4

[0108] The TFT alkali-free glass substrate of Comparative Example 4 comprises the following components by mass percentage: 62% of SiO2, 15% of Al2O3, 5% of B2O3, 4.8% of MgO, 3.2% of SrO, 4% of CaO, 0.96% of BaO, 0.5% of Y2O3, 0.54% of La2O3, 1% of ZnO, 2% of ZrO2, and 1% of SnO2.

[0109] The preparation method of the TFT alkali-free glass substrate of Comparative Example 4 is the same as that of Example 1.

[0110] Perform performance tests on the TFT alkali-free glass substrate prepared in Comparative Example 4:

[0111] Interface binding energy: Measured by the scratch method, the interface binding energy is 2.4 J / m 2 .

[0112] Transparency: Tested by a spectrophotometer, the average transmittance reaches 91% in the visible light range (400 - 760 nm).

[0113] Al and N generated by the decomposition of AlN in the glass 3+ and N 3- have an important impact on the glass performance. Therefore, AlN is not added in Comparative Example 4, oxygen vacancy generation cannot be inhibited, the thermal stability of the glass decreases, and the critical temperature of phase separation decreases. At the same time, Al 3+ cannot participate in the formation of the network structure, the network strength weakens, resulting in a certain degree of influence on the interface binding energy and transparency. However, since other components can still play a partial role, the performance degradation is relatively small.

[0114] Comparative Example 5

[0115] The formula of the TFT alkali-free glass substrate of Comparative Example 5 is the same as that of Example 1.

[0116] The difference between the preparation method of the TFT alkali-free glass substrate of Comparative Example 5 and that of Example 1 is that steps S5 and S6 are not carried out.

[0117] Perform performance tests on the TFT alkali-free glass substrate prepared in Comparative Example 5:

[0118] Interface binding energy: Measured by the scratch method, the interface binding energy is 2.2 J / m 2 .

[0119] Transparency: Tested by a spectrophotometer, the average transmittance reaches 90% in the visible light range (400 - 760 nm).

[0120] Depositing the SiO2-Al2O3-ZrO2 composite film and performing heat treatment can form a crack passivation structure, promote the migration of alkaline earth metal ions, enhance the interfacial binding energy, and eliminate the internal stress of the glass. Therefore, when the above treatment is not performed in Comparative Example 5, the glass substrate cannot obtain these performance improvements, resulting in a relatively low interfacial binding energy and ineffective elimination of internal stress, thereby affecting comprehensive properties such as transparency.

[0121] Comparative Example 6

[0122] The formulation of the TFT alkali-free glass substrate in Comparative Example 6 is the same as that in Example 1.

[0123] The preparation method of the TFT alkali-free glass substrate in Comparative Example 6 is different from that in Example 1 in that in step S5 deposition: after the glass substrate is formed, a SiO2-Al2O3 composite film with a thickness of 100 nm is deposited on the surface of the glass substrate by physical vapor deposition (PVD), where the SiO2 content is 70 wt.%, and the Al2O3 content is 30 wt.%.

[0124] Performance tests were carried out on the TFT alkali-free glass substrate prepared in Comparative Example 6:

[0125] Interfacial binding energy: Measured by the scratch method, the interfacial binding energy was measured to be 2 J / m 2 。

[0126] Transparency: Tested by a spectrophotometer, the average transmittance reached 90% in the visible light range (400 - 760 nm).

[0127] ZrO2 was not added to the composite film in Comparative Example 6, and the phase change of ZrO2 under stress could not be used to generate a compressive stress field to force crack deflection or closure, nor could a Zr-O-M bond be formed to strengthen the interfacial binding. Although SiO2 and Al2O3 can improve the interfacial performance to a certain extent, the effect is not as good as that of the composite film containing SiO2, Al2O3, and ZrO2 at the same time, resulting in limited improvement in interfacial binding energy and transparency.

[0128] Comparative Example 7

[0129] The formulation of the TFT alkali-free glass substrate in Comparative Example 7 is the same as that in Example 1.

[0130] The preparation method of the TFT alkali-free glass substrate in Comparative Example 7 is different from that in Example 1 in that in step S5 deposition: after the glass substrate is formed, a SiO2-ZrO2 composite film with a thickness of 100 nm is deposited on the surface of the glass substrate by physical vapor deposition (PVD), where the SiO2 content is 80 wt.%, and the ZrO2 content is 20 wt.%.

[0131] Performance tests were carried out on the TFT alkali-free glass substrate prepared in Comparative Example 7:

[0132] Interface binding energy: Measured by the scratch method, the interface binding energy is 2.2 J / m 2 .

[0133] Transparency: Tested by a spectrophotometer, the average transmittance reaches 90% in the visible light range (400 - 760 nm).

[0134] In the composite film of Comparative Example 7, Al2O3 was not added. Al in the composite film 3+ could not fill the glass network gaps to form [AlO4] tetrahedrons with alkaline earth metals to enhance the crosslinking density, nor could it utilize the high melting point of Al2O3 to improve the high-temperature stability of the composite film. Therefore, the interface binding energy and transparency were affected and decreased compared with the examples.

[0135] Comparative Example 8

[0136] The formulation of the alkali-free glass substrate for TFT in Comparative Example 8 is the same as that in Example 1.

[0137] The preparation method of the alkali-free glass substrate for TFT in Comparative Example 8 is different from that in Example 1 in that in step S5 deposition: after the glass substrate is formed, a 100-nm-thick Al2O3-ZrO2 composite film is deposited on the surface of the glass substrate by physical vapor deposition (PVD), where the content of Al2O3 is 70 wt.% and the content of ZrO2 is 30 wt.%.

[0138] Perform performance tests on the alkali-free glass substrate for TFT prepared in Comparative Example 8:

[0139] Interface binding energy: Measured by the scratch method, the interface binding energy is 2 J / m 2 .

[0140] Transparency: Tested by a spectrophotometer, the average transmittance reaches 89% in the visible light range (400 - 760 nm).

[0141] In the composite film of Comparative Example 8, SiO2 was not added. The composite film could not form continuous chemical bonds with SiO2 in the glass substrate to reduce the interface energy, nor could it reduce interface defects through covalent bonds. Although Al2O3 and ZrO2 could play a partial role, the overall interface performance and transparency improvement were not as good as that of the complete SiO2-Al2O3-ZrO2 composite film, resulting in relatively low performance.

Claims

1. A TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition, characterized in that: The invention comprises the following components in percentage by mass: SiO2 60-65wt.%, Al2O3 15-18wt.%, B2O3 5-7wt.%, alkaline earth metal oxides 10-13%, Y2O3 0.5-1.5wt.%, La2O3 0.5-1.5wt.%, ZnO 1-3wt.%, ZrO2 1-3wt.%, AlN 1-3wt.% and clarifier 0.5-1.5wt.%; wherein the alkaline earth metal oxides comprise MgO, SrO, CaO and BaO, and the mass ratio of MgO to SrO is (2.5-3.5):2, the mass ratio of CaO to BaO is (3.5-4.5):1, and the mass ratio of MgO to BaO is (4.5-5.5):

1.

2. The TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition according to claim 1, characterized in that: The clarifier is SnO2.

3. The method for preparing a TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition according to claim 1 or 2, characterized in that: The following steps are involved: S1: mixing raw materials: mixing the raw materials of each component evenly to obtain a mixture; S2 melting: putting the mixed material into a melting furnace for melting to obtain glass liquid; S3 overflow molding: the glass liquid overflows onto the molding device through the overflow tank, so that the glass liquid is molded into a glass substrate; S4 annealing: the glass substrate enters the annealing furnace for annealing treatment; S5 deposition: after the glass substrate is formed, a layer of SiO2-Al2O3-ZrO2 composite film is deposited on the surface of the glass substrate by physical vapor deposition or chemical vapor deposition, wherein the SiO2 content is 50-70wt.%, the Al2O3 content is 20-30wt.%, and the ZrO2 content is 10-20wt.%; S6 heat treatment: the glass substrate after the SiO2-Al2O3-ZrO2 composite film is deposited is placed in a heat treatment furnace for heat treatment to obtain a TFT alkali-free glass substrate with suppressed microcrack propagation and high interface bonding energy.

4. The method for preparing a TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition according to claim 3, characterized in that: Step S1, the raw material particle size is 80-200 mesh.

5. The method for preparing a TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition according to claim 3, characterized in that: Step S2, the melting temperature is 1550-1650°C, the melting time is 4-6h, and the glass liquid is continuously stirred at a rate of 60-100r / min during the melting process.

6. The method for preparing a TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition according to claim 3, characterized in that: Step S3, the overflow tank temperature is 1200-1300°C, and the molding speed is 0.5-1.5m / min.

7. The method for preparing a TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition according to claim 3, characterized in that: Step S4, during annealing, first keep the temperature at 670-690°C for 1-2h, then cool to 640-660°C at a rate of 1-3°C / min, keep the temperature for 0.5-1.5h, and finally cool to room temperature with the furnace.

8. The method for preparing a TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition according to claim 3, characterized in that: Step S5, the thickness of the SiO2-Al2O3-ZrO2 composite film is 50-200nm.

9. The method for preparing a TFT alkali-free glass substrate with high interface bonding energy and microcrack expansion inhibition according to claim 3, characterized in that: Step S6, the heat treatment temperature is 700-800°C, the heat treatment time is 1-3h, then the temperature is reduced to 650-670°C at a rate of 1-3°C / min, and then kept at this temperature for 1-2h, and finally cooled to room temperature with the furnace.