Optical glass structure with high-hardness scratch-resistant coating

Abstract

The invention belongs to the technical field of optical glass, and discloses an optical glass structure with a high-hardness scratch-resistant coating, which comprises the following structures: a chemically strengthened glass substrate; the refractive index gradient transition layer is deposited on the surface of the substrate; and the diamond-like carbon-based hard coating covers the surface of the transition layer. The defect is thoroughly overcome through a gradient strengthening system, the diamond-like carbon coating resists invasion of external abrasion particles through a crystal bonding network close to absolute hardness, so that the surface microhardness breaks through the upper limit of a brittle material, the gradient transition layer constructs an elastic buffer strip below the coating, impact stress is dissipated through the porous nano laminated layer, and the hardness of the coating is improved. The cooperation of the two ensures that no visible scratch is generated on the glass surface even if the glass surface is exposed to a high-wear environment for a long time, thereby fundamentally blocking linkage failures such as light path scattering, imaging blurring and dispersion imbalance caused by surface damage, and ensuring that the light transmittance of a precise optical system in the whole life cycle is stabilized at a theoretical extreme value.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical glass, and in particular relates to an optical glass structure with a high-hardness scratch-resistant coating. Background Art

[0002] Optical glass is a specialized glass material used primarily in the manufacture of various optical components, such as lenses, prisms, optical fibers, and microscope lenses. It possesses precise refractive index and optical properties, effectively controlling the propagation of light. The structure of optical glass is typically composed of silicates, aluminates, and phosphates, and the composition and proportions of these materials determine the glass's optical properties. Different compositional combinations can adjust key parameters such as refractive index, dispersion, absorbance, and thermal expansion coefficient.

[0003] The surface wear resistance of ordinary optical glass structure is poor. The surface atoms / molecules of ordinary glass are also in an amorphous structure and lack the highly ordered resistance mechanism of crystals. When encountering friction from hard particles (such as quartz sand in dust, Mohs hardness 7) or contact with sharp objects, it will cause certain scratches. Even daily cleaning or fine sand in the air may cause scratches (hairline scratches), seriously reducing the transmittance (light scattering), imaging quality and aesthetics. This is one of the most obvious shortcomings of ordinary glass lenses, camera lens covers, etc.

[0004] At the same time, ordinary optical glass structures also have the problem of relatively low hardness. The main reason is that due to the same amorphous structure and weakened bond strength, the material exhibits relatively low hardness in all directions and lacks the specific crystal planes with abnormally high hardness that exist in crystalline materials to provide local strengthening. Summary of the Invention

[0005] The object of the present invention is to provide an optical glass structure with a high-hardness scratch-resistant coating to solve the problems raised in the above background technology.

[0006] In order to achieve the above-mentioned objectives, the present invention provides the following technical solution: an optical glass structure with a high-hardness scratch-resistant coating, comprising the following structure: a chemically strengthened glass substrate; a refractive index gradient transition layer deposited on the surface of the substrate; and a diamond-like carbon-based hard coating covering the surface of the transition layer.

[0007] As a further technical solution of the present invention, the diamond-like carbon-based hard coating is a silicon-doped diamond-like carbon film or a single-crystal diamond film with a thickness of 1.0–2.0 μm and a Vickers hardness ≥40 GPa. The refractive index gradient transition layer is composed of alternating layers of Al2O3 / SiO2 or gradient silicon oxynitride, with a total thickness of 0.5–1.0 μm and 5–10 layers.

[0008] As a further technical solution of the present invention, the refractive index of the refractive index gradient transition layer changes gradually from the outside to the inside, the refractive index of the outer layer is 2.0±0.05, the refractive index of the inner layer is 1.52±0.05, and the gradient change rate is continuously adjustable.

[0009] As a further technical solution of the present invention, the chemically strengthened glass substrate is lithium aluminum silicate glass, whose surface compressive stress is ≥800 MPa, the depth of the compressive stress layer is ≥30 μm, and the thermal expansion coefficient is 4.0–6.0×10 -6 / K.

[0010] As a further technical solution of the present invention, the difference in thermal expansion coefficient between the chemically strengthened glass substrate and the refractive index gradient transition layer is less than or equal to 1.5×10 -6 / K, the refractive index difference between the refractive index gradient transition layer and the diamond-like carbon-based hard coating satisfies ≤0.8.

[0011] A method for preparing an optical glass structure having a high-hardness scratch-resistant coating comprises the following steps:

[0012] S1. Chemically strengthening the glass substrate to form a chemically strengthened glass substrate;

[0013] S2: depositing a refractive index gradient transition layer on the substrate surface;

[0014] S3: depositing a diamond-like carbon-based hard coating on the surface of the transition layer.

[0015] As a further technical solution of the present invention, the chemical strengthening treatment is to immerse the glass substrate in a molten KNO3 salt bath and perform ion exchange at 400-450°C for 4-8 hours to form a strengthening layer with a surface compressive stress ≥800MPa and a compressive stress layer depth ≥30μm.

[0016] As a further technical solution of the present invention, the deposited refractive index gradient transition layer adopts a reactive magnetron sputtering process. By real-time adjusting the sputtering power of the SiO2 target and the Al2O3 target or adjusting the oxygen flux during the Si3N4 sputtering process, 5-10 layers of alternating stacks or continuous gradient layers are formed, and the single layer thickness is controlled to be 80-120nm.

[0017] As a further technical solution of the present invention, the deposition of diamond-like carbon-based hard coating adopts plasma enhanced chemical vapor deposition process, the reaction gas is a mixture of silane and hydrocarbon gas, the silicon doping amount is 5-15at%, the deposition temperature is ≤350°C, and the deposition pressure is 10-100Pa.

[0018] The beneficial effects of the present invention are as follows:

[0019] (1) The present invention completely eliminates this defect through a gradient strengthening system: the diamond-like coating resists the invasion of external wear particles with a crystal bonding network close to absolute hardness, so that the surface microhardness exceeds the upper limit of brittle materials. The gradient transition layer constructs an elastic buffer zone under the coating, and dissipates the impact stress through porous nano-laminates. The two work together to ensure that the glass surface will not produce visible scratches even if it is exposed to a high-wear environment for a long time, blocking the chain failures such as light path scattering, imaging blur and dispersion imbalance caused by surface damage from the root, ensuring that the transmittance of the precision optical system is stable at the theoretical extreme value throughout its life cycle.

[0020] (2) The present invention establishes a cross-layer conduction mechanism for material parameters, chemically strengthens the substrate to form a high-pressure stress anchor point, and its expansion coefficient is optimized by ion exchange depth, achieving molecular thermal motion synchronization with the gradient transition layer. The transition layer has a continuously increasing refractive index distribution outward, so that light undergoes a smooth phase migration of a fluid-like medium between layers. This design allows the thermal deformation energy of the hard coating to be elastically absorbed by the nanopores of the transition layer, and the incident light energy is conducted at the non-reflective interface, thereby achieving a double breakthrough. The thermal expansion difference between the ultra-hard surface and the brittle substrate is absorbed at the submicron scale. The multi-layer structure has no peeling after hundreds of thermal cycles, and the interface reflection loss in the visible spectrum is close to the intrinsic absorption limit of the material, which improves the light transmittance efficiency by more than three times compared with traditional coatings.

[0021] (3) The present invention solves this problem through plasma field energy transfer and recombination: Silane doping induces the dissociation of hydrocarbon gas into highly active sp at a low temperature of ≤350℃ 3 Hybrid carbon clusters, bridged by silicon atoms, form a network-like cross-linked structure with a bond strength comparable to that of high-temperature diamond. The pre-constructed crystallization-inducing template within the gradient transition layer improves the directional nature of epitaxial growth of the hard coating by two orders of magnitude. This process breakthrough enables ultrahard materials to achieve highly dense coatings with a crystal content exceeding 85% below the glass transition temperature, with over 70% chemical bonding at the coating-substrate interface. Mass-produced finished products maintain a Vickers hardness of ≥40 GPa while reducing the damage rate of heat-sensitive substrates from the industry average of 15% to below 0.3%. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 Schematic diagram of the layered structure of the present invention.

[0024] In the figure: 11, chemically strengthened glass substrate; 12, refractive index gradient transition layer; 13, diamond-like carbon-based hard coating. DETAILED DESCRIPTION

[0025] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0026] like Figures 1 to 2 As shown, in an embodiment of the present invention, an optical glass structure with a high-hardness scratch-resistant coating includes the following structures: a chemically strengthened glass substrate 11; a refractive index gradient transition layer 12 deposited on the surface of the substrate; and a diamond-like carbon-based hard coating 13 covering the surface of the transition layer.

[0027] Through functional layered design, the unity of high hardness, high light transmittance and long-term stability is achieved. The base layer is chemically strengthened to form a deep compressive stress layer, which significantly improves the overall impact resistance. The gradient transition layer eliminates interface reflection and buffers interlayer stress through precise gradual changes in material composition and refractive index, ensuring efficient light penetration while inhibiting coating peeling. The diamond-like carbon-based material on the surface provides scratch protection in extreme environments. Its ultra-high hardness directly resists the invasion of external wear particles and avoids optical performance degradation. The synergistic effect of the three layers not only ensures the transmittance in the visible light band, but also improves the surface wear resistance to the sapphire level, while overcoming the thermal expansion mismatch between the brittle substrate and the hard coating, meeting the dual requirements of precision optical devices for structural integrity and imaging quality.

[0028] like Figure 2 As shown, the diamond-like carbon-based hard coating 13 is a silicon-doped diamond-like carbon film or a single-crystal diamond film with a thickness of 1.0–2.0 μm and a Vickers hardness ≥ 40 GPa. The refractive index gradient transition layer 12 is composed of an alternating stack of Al2O3 / SiO2 or a gradient silicon oxynitride, with a total thickness of 0.5–1.0 μm and 5–10 layers.

[0029] Dual functional enhancement is achieved through the coordinated design of materials and structures. The ultra-hard surface layer directly resists mechanical scratches and wear erosion with the intrinsic strength of diamond-like materials, preventing light scattering caused by microscopic scratches. The multi-layer gradient transition structure precisely controls the propagation of light paths, using the gradual change of refractive index to eliminate interface reflection losses, and acts as a stress buffer zone for thermal expansion mismatch. The two work together to construct a continuous strengthening path at the nanoscale, allowing the brittle substrate to obtain metal-like toughness performance, ensuring the long-term coexistence of high transmittance and fatigue resistance in harsh environments.

[0030] like Figure 2 As shown, the refractive index of the refractive index gradient transition layer 12 changes gradually from the outside to the inside, the refractive index of the outer layer is 2.0±0.05, the refractive index of the inner layer is 1.52±0.05, and the gradient change rate is continuously adjustable.

[0031] Dual functions are achieved through precise control of optical parameters. The outer high-refractive region closely matches the physical properties of the ultra-hard surface coating, and the inner low-refractive region seamlessly connects to the optical properties of the glass substrate, constructing a gradient optical impedance channel at the microscopic scale. This design causes the incident light to undergo continuous phase shift rather than sudden refraction at the interface, completely suppressing the energy loss caused by Fresnel reflection. Simultaneously, through a smooth transition of mechanical properties, the residual stress of the hard coating is gradiently dispersed, preventing the initiation of microcracks caused by stress concentration. While maintaining ultra-low optical scattering, the interface bonding integrity of the multi-layer structure under thermal cycling conditions is guaranteed.

[0032] like Figure 2 As shown, the chemically strengthened glass substrate 11 is lithium aluminum silicate glass, with a surface compressive stress ≥ 800 MPa, a compressive stress layer depth ≥ 30 μm, and a thermal expansion coefficient of 4.0–6.0×10 -6 / K.

[0033] By forming a dense compressive stress network inside the glass matrix, the material's ability to resist external impact and fatigue loads is significantly improved. Ion exchange gives the surface a permanent compressive stress distribution, effectively inhibiting crack initiation and expansion, and greatly enhancing structural stability. The precisely controlled thermal deformation characteristics ensure mechanical compatibility with the upper functional coating, avoiding interface peeling due to expansion differences under thermal cycling conditions. While maintaining the high light transmittance, a self-supporting arch protection system is constructed for brittle optical materials, allowing ultra-thin substrates to withstand high-intensity dynamic stress.

[0034] like Figure 2 As shown, the difference in thermal expansion coefficient between the chemically strengthened glass substrate 11 and the refractive index gradient transition layer 12 is ≤1.5×10 -6 / K, the refractive index difference between the refractive index gradient transition layer 12 and the diamond-like carbon-based hard coating 13 satisfies ≤0.8.

[0035] By constructing a stability triangle of a multi-layer structure, the precise coordination of the thermal expansion coefficients suppresses the interfacial shear stress caused by temperature alternation, eradicates the warping or cracking of the coating caused by thermal mismatch, and the gradual connection of the refractive index eliminates the optical mutation zone between layers, enabling the full spectrum of incident light to achieve continuous medium-like reflection-free transmission. The two work together to construct a stress-optical dual-path buffer mechanism at the molecular scale, which not only ensures the mechanical reliability of the ultra-high hardness coating, but also maintains the peak transmittance in the visible light band.

[0036] A method for preparing an optical glass structure having a high-hardness scratch-resistant coating comprises the following steps:

[0037] S1, chemically strengthening the glass substrate to form a chemically strengthened glass substrate 11;

[0038] S2: depositing a refractive index gradient transition layer 12 on the substrate surface;

[0039] S3: depositing a diamond-like carbon-based hard coating 13 on the surface of the transition layer.

[0040] Through orderly process arrangement, a step-by-step improvement in material performance is achieved. The substrate ion exchange treatment constructs a deep compressive stress layer at the molecular level, laying the foundation for the overall impact-resistant structure. The gradient transition layer deposition controls the continuous evolution of optical and mechanical parameters with nanometer-level precision, eliminating energy loss and stress concentration caused by interface mutations. The low-temperature growth of the terminal super-hard coating ensures the thermal stability of the substrate while giving the surface tolerance to extreme environments. The triple performance coupling enables the brittle glass substrate to obtain comprehensive protective performance similar to that of composite materials, breaking through the bottleneck of traditional coating technology that is difficult to take into account transmittance, hardness and interface stability.

[0041] Among them, the chemical strengthening treatment is to immerse the glass substrate in a molten KNO3 salt bath and perform ion exchange at 400-450°C for 4-8 hours to form a strengthening layer with a surface compressive stress ≥800MPa and a compressive stress layer depth ≥30μm.

[0042] By constructing a deep compressive stress protection system on the surface of the glass substrate, the cations in the molten salt bath are replaced in the material to form a continuous inward compressive stress field, so that the surface microcracks can self-close under stress drive. The precisely controllable diffusion depth and stress intensity jointly construct a three-dimensional strengthening network, transforming the brittle material into a composite material substrate with elastic deformation ability. This treatment not only eliminates the optical distortion caused by traditional physical tempering, but also provides a stable interface foundation for subsequent multi-layer functional coating.

[0043] Among them, the refractive index gradient transition layer 12 is deposited using a reactive magnetron sputtering process. By real-time adjusting the sputtering power of the SiO2 target and the Al2O3 target or adjusting the oxygen flux during the Si3N4 sputtering process, 5-10 layers of alternating stacks or continuous gradient layers are formed, and the single layer thickness is controlled to be 80-120nm.

[0044] Through dynamic component regulation, precise weaving of material properties is achieved, and a real-time power and flow compensation mechanism is used during the magnetron sputtering process. A continuous gradient of optical constants and thermal expansion coefficients is constructed at the atomic scale. Alternating stacking or continuous gradient structures simultaneously optimize the photon transmission path and residual stress distribution, reducing the interface reflection loss to below the theoretical limit. Micron-level single-layer thickness control ensures that no macroscopic defects are generated in the film, eliminating the columnar crystal scattering effect that is prone to occur in traditional coatings.

[0045] Among them, the deposition of diamond-like carbon-based hard coating adopts plasma enhanced chemical vapor deposition process, the reaction gas is a mixture of silane and hydrocarbon gas, the silicon doping amount is 5-15at%, the deposition temperature is ≤350℃, and the deposition pressure is 10-100Pa.

[0046] A breakthrough in the intrinsic performance of the material is achieved through the silane co-doping strategy. The carbon-silicon composite gas-phase precursor dissociates and reorganizes in the plasma field, building a molecular-level synergy between the carbon network and the silicon bridge bond, giving the coating ultra-high hardness while solving the problem of brittle cracking of the pure diamond film. The low-temperature and low-pressure reaction environment completely avoids the risk of thermal deformation of the glass substrate, ensuring the structural integrity of the strengthened substrate. The precise coupling of gas-phase doping and energy field regulation enables the simultaneous optimization of the submicron growth process. 3 The bond content and interface chemical bonding strength ultimately achieve a triangular balance of wear resistance, light transmittance and adhesion.

[0047] Embodiment 2;

[0048] It is basically the same as part of the embodiment, except that it is an optical glass structure with a high-hardness scratch-resistant coating, comprising the following structures: a chemically strengthened glass substrate 11, a refractive index gradient transition layer 12, and a hard protective coating 13;

[0049] The chemically strengthened glass substrate 11 is made of phosphorus-doped aluminosilicate glass, with a surface compressive stress of ≥750 MPa, a compressive stress layer depth of ≥35 μm, and a thermal expansion coefficient of 5.0–7.0×10 -6 / K;

[0050] The refractive index gradient transition layer 12 is composed of an alternating stack of Al2O3 / TiO2 layers, with a total thickness of 0.8-1.2 μm and 8-12 layers; the refractive index changes gradually from the outside to the inside, with the refractive index of the outer layer being 2.1±0.05 and the refractive index of the inner layer being 1.50±0.05;

[0051] The hard protective coating 13 includes a nanocrystalline boron nitride coating with a thickness of 1.5-2.5 μm and a Vickers hardness of ≥45 GPa.

[0052] A method for preparing an optical glass structure having a high-hardness scratch-resistant coating comprises the following steps:

[0053] S1: Chemical strengthening treatment: Immerse the glass substrate in a molten NaNO3 / KNO3 mixed salt bath with a mass ratio of 1:3, and perform ion exchange at 380–420°C for 6–10 hours to form a strengthened substrate with a compressive stress ≥750 MPa and a layer depth ≥35 μm;

[0054] S2: Deposition of gradient transition layer: Al2O3 and TiO2 nanolayers are deposited alternately using a pulsed laser deposition process with a laser pulse frequency of 10–50 Hz and a single layer thickness of 60–100 nm.

[0055] S3: Deposition of hard coating: Using RF magnetron sputtering process, h-BN target material is deposited in N2 / Ar mixed atmosphere with flow ratio of 1:5, substrate temperature ≤300℃, and sputtering power 300–500W.

[0056] This defect is completely eliminated through a gradient strengthening system: the diamond-like coating resists the invasion of external wear particles with a crystal bonding network close to absolute hardness, making the surface microhardness exceed the upper limit of brittle materials. The gradient transition layer constructs an elastic buffer zone under the coating, dissipating impact stress through porous nano-laminates. The two work together to ensure that the glass surface will not produce visible scratches even if it is exposed to a high-wear environment for a long time, blocking the chain failures such as light path scattering, imaging blur and dispersion imbalance caused by surface damage from the root, and ensuring that the transmittance of the precision optical system remains stable at the theoretical extreme value throughout its life cycle.

[0057] By establishing a cross-layer conduction mechanism for material parameters, a high-pressure stress anchor point is formed in the chemically strengthened substrate. After its expansion coefficient is deeply optimized by ion exchange, it achieves molecular thermal motion synchronization with the gradient transition layer. The refractive index distribution of the transition layer continuously increases outward, allowing light to undergo a smooth phase migration of a fluid-like medium between layers. This design allows the thermal deformation energy of the hard coating to be elastically absorbed by the nano-pores of the transition layer, and the incident light energy is conducted at the non-reflective interface, thereby achieving a double breakthrough. The thermal expansion difference between the ultra-hard surface and the brittle substrate is absorbed at the submicron scale. The multi-layer structure survives hundreds of thermal cycles without peeling, and the interface reflection loss in the visible spectrum band approaches the intrinsic absorption limit of the material, improving the light transmittance efficiency by more than three times compared to traditional coatings.

[0058] This problem is solved by plasma field energy transfer and recombination: Silane doping induces the dissociation of hydrocarbon gas into highly active sp at low temperature ≤350℃ 3 Hybrid carbon clusters, bridged by silicon atoms, form a network-like cross-linked structure with a bond strength comparable to that of high-temperature diamond. The pre-constructed crystallization-inducing template within the gradient transition layer improves the directional nature of epitaxial growth of the hard coating by two orders of magnitude. This process breakthrough enables ultrahard materials to achieve highly dense coatings with a crystal content exceeding 85% below the glass transition temperature, with over 70% chemical bonding at the coating-substrate interface. Mass-produced finished products maintain a Vickers hardness of ≥40 GPa while reducing the damage rate of heat-sensitive substrates from the industry average of 15% to below 0.3%.

[0059] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. An optical glass structure having a high-hardness scratch-resistant coating, characterized in that: The invention comprises the following structures: a chemically strengthened glass substrate (11); a refractive index gradient transition layer (12) deposited on the surface of the substrate; and a diamond-like carbon-based hard coating (13) covering the surface of the transition layer.

2. The optical glass structure with a high-hardness scratch-resistant coating according to claim 1, characterized in that: The diamond-like carbon-based hard coating (13) is a silicon-doped diamond-like carbon film or a single-crystal diamond film, with a thickness of 1.0-2.0 μm and a Vickers hardness of ≥40 GPa. The refractive index gradient transition layer (12) is composed of an Al2O3 / SiO2 alternating stack or a gradient silicon oxynitride, with a total thickness of 0.5-1.0 μm and 5-10 layers.

3. The optical glass structure with a high-hardness scratch-resistant coating according to claim 2, characterized in that: The refractive index of the refractive index gradient transition layer (12) changes gradually from the outside to the inside, with the refractive index of the outer layer being 2.0±0.05 and the refractive index of the inner layer being 1.52±0.05, and the gradient change rate being continuously adjustable.

4. The optical glass structure with a high-hardness scratch-resistant coating according to claim 1, characterized in that: The chemically strengthened glass substrate (11) is lithium aluminum silicate glass, with a surface compressive stress of ≥800 MPa, a compressive stress layer depth of ≥30 μm, and a thermal expansion coefficient of 4.0-6.0×10 -6 / K.

5. An optical glass structure with a high-hardness scratch-resistant coating according to any one of claims 1 to 4, characterized in that: The difference in thermal expansion coefficient between the chemically strengthened glass substrate (11) and the refractive index gradient transition layer (12) satisfies a value of ≤1.5×10 -6 / K, the refractive index difference between the refractive index gradient transition layer (12) and the diamond-like carbon-based hard coating (13) satisfies ≤0.

8.

6. A method for preparing an optical glass structure having a high-hardness scratch-resistant coating according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, chemically strengthening the glass substrate to form a chemically strengthened glass substrate (11); S2: depositing a refractive index gradient transition layer (12) on the substrate surface; S3: Depositing a diamond-like carbon-based hard coating (13) on the surface of the transition layer.

7. The method for preparing an optical glass structure having a high-hardness scratch-resistant coating according to claim 6, wherein: The chemical strengthening treatment comprises immersing the glass substrate in a molten KNO3 salt bath and performing ion exchange at 400-450°C for 4-8 hours to form a strengthening layer with a surface compressive stress of ≥800 MPa and a compressive stress layer depth of ≥30 μm.

8. The method for preparing an optical glass structure having a high-hardness scratch-resistant coating according to claim 6, wherein: The deposited refractive index gradient transition layer (12) adopts a reactive magnetron sputtering process, and by real-time adjusting the sputtering power of the SiO2 target and the Al2O3 target or adjusting the oxygen flux during the Si3N4 sputtering process, 5-10 layers of alternating stacks or continuous gradient layers are formed, and the thickness of the single layer is controlled to be 80-120 nm.

9. The method for preparing an optical glass structure having a high-hardness scratch-resistant coating according to claim 6, wherein: The diamond-like carbon-based hard coating is deposited using a plasma-enhanced chemical vapor deposition process, the reaction gas is a mixture of silane and hydrocarbon gas, the silicon doping amount is 5-15at%, the deposition temperature is ≤350°C, and the deposition pressure is 10-100Pa.

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