Boron-doped silicon oxide protective layer and method for manufacturing the same

Abstract

The present invention relates to a glass substrate (10) having a multilayer coating comprising a boron-doped silicon oxide protective layer (P), the boron-doped silicon oxide containing Si, O, B and OH groups and having a boron content of 4-12 atomic %. The present invention further includes a process for depositing, by means of hollow cathode linear PECVD, a boron-doped silicon oxide layer containing Si, O, B and OH groups and having a boron content of 4-12 atomic % on a glass substrate.

Description

Technical Field

[0001] The present invention relates to a glass substrate having a multilayer coating including a boron-doped silicon oxide layer for protecting the multilayer coating from chemical degradation. The present invention further relates to a plasma-enhanced chemical vapor deposition method for depositing such a protective layer on a large glass substrate having a size of, for example, at least 3.2 x 6 m 2 The protective layer of the present invention can further maintain a refractive index very close to that of undoped silicon oxide.

Background Art

[0002] Multilayer coatings can provide various properties to the coated glass substrate, and in particular can provide solar control, heat insulation, anti-reflection and / or bird collision prevention properties.

[0003] Such coatings are often deposited using magnetron sputtering and are composed of, for example, dielectric layers, transparent conductive oxide layers, metal layers, etc. These coatings are exposed to mechanical and chemical stresses during handling, transportation, and processing into finished windows. In these processes, the multilayer coating is exposed to conditions that can lead to corrosion of the coating, and defects such as point defects and peeling occur.

[0004] Protective coatings for glass substrates are known in the glazing field. These are usually used to impart additional resistance to various mechanical and / or chemical attacks to magnetron sputter coatings.

[0005] For example, Patent Document 1 describes a glass substrate provided with a solar control or low-E insulating coating having a protective top coat based on titanium oxide and an additional oxide such as ZrO2, SiO2 or Cr2O3. This protective top coat provides mechanical and chemical durability, but the refractive index of these coatings is high, generally at least 2.0 at a wavelength of 633 nm. Such a high refractive index layer tends to increase the reflectivity of the resulting coating stack, especially when thick, which is undesirable for many applications, so its thickness is limited.

[0006] Patent Document 2 discloses a protective top coat with a low refractive index made from a mixed oxide of aluminum and silicon. However, these protective top coats are not very economically attractive due to their low deposition rate. Furthermore, they have been found to be insufficiently resistant to mechanical and chemical degradation.

[0007] Patent Document 3 discloses a plasma-enhanced chemical vapor deposition SiO2 layer having a good deposition rate and good resistance to heat treatment. However, it has been found that the chemical resistance of these layers still has room for improvement.

[0008] Therefore, there is a need in the art for a layer that can improve the resistance of multilayer coatings to chemical degradation, has a low refractive index, and can be deposited at a high deposition rate.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0010] An object of the present invention is to provide a glass substrate having a multilayer coating including a protective layer that imparts high chemical resistance to a coated substrate and preferably has a low refractive index in the visible light range.

Means for Solving the Problems

[0011] Accordingly, the present invention relates to a glass substrate having a multilayer coating including a protective layer of boron-doped silicon oxide, the boron-doped silicon oxide containing Si, O, B and OH groups, and having a boron content of 4-12 atomic %.

[0012] Another object of the present invention is to provide a method for depositing a protective layer of boron-doped silicon oxide, the boron-doped silicon oxide containing Si, O, B and OH groups, and having a boron content of 4-12 atomic %.

[0013] In a specific embodiment of the present invention, the process of depositing a protective layer of boron-doped silicon oxide containing Si, O, B and OH groups and having a boron content of 4-12 atomic % on a glass substrate includes the following steps: a. Providing a glass substrate b. Providing a linear hollow cathode plasma source having a length and including at least one pair of hollow cathode plasma generating electrodes, the at least one pair of electrodes being connected to an AC, DC or pulsed DC power source for depositing the protective layer on the substrate c. Injecting a plasma generating reactive gas containing oxygen into the electrodes of the plasma source at a flow rate of 125-750 sccm per linear meter of the length of the plasma source d. Applying power to the plasma source at a power of 10-50 kW per linear meter of the length of the plasma source e. Injecting a precursor gas at a flow rate of 500-2500 sccm per linear meter of the length of the plasma source, injecting the precursor gas into the plasma between at least the electrodes of each electrode pair of the plasma source, and depositing a protective layer on the glass substrate by exposing the substrate to the plasma of the plasma source

[0014] To more fully understand the features of the present invention, reference is made to the following detailed description in conjunction with the accompanying drawings.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Modes for Carrying Out the Invention

[0016] A multilayer coating is a coating composed of two or more thin layers. The thin layer is a layer with a maximum thickness of 1 μm. A glass substrate with modified optical properties and / or energy properties is provided by the multilayer coating.

[0017] In a specific embodiment of the present invention, the coating is selected from an anti-reflection coating, an ultraviolet (UV) reflection coating for preventing bird collisions, an insulating low-emissivity coating, and a solar control coating. In a specific embodiment of the present invention, the boron-doped silicon oxide layer is a protective top coat in the coating provided on the substrate, that is, the last or topmost layer of the multilayer coating farthest from the substrate. The boron-doped silicon oxide layer of the present invention may alternatively be used at other positions in the layer sequence constituting the multilayer coating.

[0018] In one embodiment of the present invention, the protective layer can have a refractive index of 1.4 - 1.8 at a wavelength of 633 nm and / or can contain at least 80 wt% of SiO2. Since in a multilayer coating, a thick and low refractive index layer can be replaced by a thin and low refractive index layer, the multilayer coating can benefit from the improvement in protection by the thick protective layer.

[0019] In a particular embodiment of the present invention, the coating is an antireflection coating in which a high refractive index layer and a low refractive index layer are alternately laminated, and the boron-doped silicon oxide layer is one of the low refractive index layers, preferably the protective topcoat layer. The low refractive index layer may be a layer having a refractive index of 1.4 - 1.8 at a wavelength of 633 nm and containing at least 80 wt% of SiO2. The high reflection layer may be selected from layers having a refractive index of at least 2.0 at a wavelength of 633 nm and containing, for example, any of titanium oxide, mixed titanium zirconium oxide, niobium oxide, and a mixed nitride of silicon and zirconium. The substrate thus antireflection coated has a lower visible light reflectance than the uncoated substrate.

[0020] Figure 3 shows a glass substrate (10) with a multilayer coating of alternating high refractive index layers (H1, H2) and low refractive index layers (L1, P), and an optional layer (O) for mechanical protection. One of the low refractive index layers (P) is a boron-doped silicon oxide protective layer according to an embodiment of the present invention.

[0021] In certain embodiments of the present invention, the coating is an ultraviolet reflective coating, such as a bird strike prevention coating, and the boron-doped silicon oxide layer is a low refractive index layer, preferably a protective topcoat layer. Such an ultraviolet reflective coating generally consists of alternating high refractive index layers and low refractive index layers. The low refractive index layer may be a layer having a refractive index of 1.4 - 1.8 at a wavelength of 633 nm and containing at least 80 wt% of SiO2. The high reflective layer may be selected from layers having a refractive index of at least 2.0 at a wavelength of 633 nm and containing, for example, any of titanium oxide, mixed titanium zirconium oxide, niobium oxide, and a mixed nitride of silicon and zirconium. The substrate thus coated with the ultraviolet reflective coating has a higher ultraviolet reflectivity than an uncoated substrate.

[0022] In one embodiment, the present invention relates to a multilayer coating comprising n functional layers (S) that reflect infrared radiation and n + 1 dielectric coatings (n ≧ 1), each functional layer being surrounded by a dielectric coating. The dielectric coating can include one or more dielectric layers selected from, for example, layers of oxides, nitrides, or oxynitrides of metals or silicon, or mixtures thereof, and / or the boron-doped silicon oxide protective layer of the present invention. The one or more dielectric layers can be selected from, for example, mixed zinc tin oxide, silicon nitride, mixed tin antimony oxide, zinc oxide, titanium oxide, and mixed titanium zirconium oxide. In particular, the uppermost layer farthest from the substrate may be the boron-doped silicon oxide protective layer of the present invention.

[0023] Multilayer low-emissivity insulating coatings generally include a single functional layer that reflects infrared radiation, while multilayer coatings having low emissivity and solar-reflecting properties generally include two or three functional layers that reflect infrared radiation. The functional layer that reflects infrared radiation in the multilayer coating of the present invention is preferably a silver-based layer, which consists of silver or silver doped with, for example, palladium or gold, and the proportion thereof is up to 5% by weight, preferably about 1% by weight. Incorporating a small amount of such a dopant into the silver-based layer may improve the chemical durability of the coating stack. In an advantageous embodiment, the thickness of the functional layer is at least 6 nm or at least 8 nm, preferably at least 10 nm, and the thickness is preferably at most 22 nm or at most 20 nm, preferably at most 18 nm or at most 16 nm. Such a thickness range can achieve the required low emissivity and / or solar-reflecting properties while limiting the light absorption of these layers. In the case of a multilayer coating having two functional layers that reflect infrared radiation, the thickness of the second functional layer, i.e., the functional layer farthest from the substrate, may preferably be slightly thicker than the thickness of the first functional layer. For example, the thickness of the first functional layer is 8-18 nm, and the thickness of the second functional layer is 10-20 nm.

[0024] According to an embodiment of the present invention, at least one dielectric layer above or below the functional layer includes a layer essentially consisting of boron-doped silicon oxide. This means that, for example, in a stacked configuration of a single functional layer, the boron-doped silicon oxide layer is present in the second upper dielectric coating or the first lower dielectric coating, and in a multilayer coating having two functional layers, the boron-doped silicon oxide layer is present in the first, second, or third dielectric coating, or any two dielectric coatings, or each of the three dielectric coatings.

[0025] FIG. 4 shows a glass substrate (10) having a multilayer coating including two silver functional layers (F1, F2) each surrounded by dielectric layers (D1-D6), and further including a boron-doped silicon oxide protective layer (P) of the present invention as the uppermost layer.

[0026] In one embodiment of the present invention, the boron-doped silicon oxide protective layer of the present invention is another gold or metal alloy layer, such as Cr and NiCr alloys or stainless steel, which is an infrared reflection functional layer other than the silver-based layer, and a transparent conductive oxide layer, such as ITO (indium-doped tin oxide), and is a layer of a multilayer coating. One example is, for example, a first layer of oxides of titanium, zirconium and / or niobium on a glass substrate, a second layer consisting of at least 85% by weight of SiO2, a third layer of indium-doped tin oxide, a fourth layer of boron-doped silicon oxide according to any of the examples described herein, and optionally a fifth layer of zirconium-doped silicon oxide, a mixed titanium zirconium oxide layer, a zirconium oxide layer or a mixed silicon zirconium nitride layer, etc., which provides further enhanced mechanical protection.

[0027] The boron-doped silicon oxide protective layer of the present invention contains OH groups. The presence of OH groups is a characteristic that distinguishes these coatings from magnetron sputtering coatings that do not provide the same level of protection. As far as the inventors know, it is considered that the boron-doped silicon oxide layer of the present invention has a protective ability at least partially due to this combination of OH groups and boron doping. The presence of OH groups can be determined by Fourier transform infrared spectroscopy (FTIR) for equivalent protective layers deposited on a silicon substrate. The presence of OH groups in the protective layer is detected by the presence of an absorption peak at a wave number of 3300 - 3500 cm -1 corresponding to the -OH stretching vibration. An additional absorption peak corresponding to the Si-OH stretching vibration may be seen between 900 - 1000 cm -1 , but these peaks may overlap with the peaks of the stronger Si-O stretching vibration.

[0028] In one embodiment of the present invention, the FTIR absorption peak area ratio A OH of the -OH stretching vibration (A SiOSi ) and the Si-O-Si stretching vibration (A OH ) is 0.25 - 0.5. The absorption peak of the -OH stretching vibration is at a wave number of 3300 - 3500 cm SiOSi -1 ​appears at a wavenumber of 1080 - 1090 cm for the absorption peak of Si - O - Si stretching vibration -1 appears.

[0029] In SiO2 - based coatings deposited by sputtering, hydrogen may unintentionally exist in the gas phase, but the FTIR absorption peak area ratio A OH / A SiOSi is known to be less than 0.05. Furthermore, SiO2 - based coatings deposited by sputtering usually contain aluminum because aluminum is added to the silicon sputtering target to enhance conductivity. The boron - doped silicon oxide layer of the present invention may not contain aluminum.

[0030] The boron - doped silicon oxide layer of the present invention was found to be amorphous and non - porous when observed with, for example, a transmission electron microscope.

[0031] The boron - doped silicon oxide layer of the present invention may contain, or may be essentially composed of, silicon, boron, oxygen, and hydrogen.

[0032] In any of the above embodiments, the boron - doped silicon oxide layer has a boron content of 4 - 12 atomic %. Within this doping range, the refractive index is very low and is maintained in the range of 1.4 - 1.5 at a wavelength of 633 nm, especially when the SiO2 weight content is at least 80%. At the same time, good chemical resistance of the multilayer coating can be obtained, and the haze level after thermal strengthening can be maintained low, especially at a value of less than 0.3%.

[0033] The boron content in the boron - doped silicon oxide layer is preferably determined by X - ray photoelectron spectroscopy (XPS) or by secondary ion mass spectrometry (SIMS) using an appropriate standard for quantitative evaluation.

[0034] According to one embodiment of the present invention, the boron-doped silicon oxide protective layer can have a thickness of at least 50 nm, preferably at least 80 nm, in order to show a more significant improvement in durability. The thickness can be adjusted over a wide range to adjust the optical properties of the final coated product. Thus, the thickness of the boron-doped silicon oxide can be up to 400 nm, particularly up to 350 nm, more specifically up to 300 nm. Such a thick thickness is not suitable for magnetron sputtering deposition because of the slow deposition rate of the silicon oxide-based coating.

[0035] According to one embodiment of the present invention, the boron-doped silicon oxide layer of the present invention can have an O / Si atomic ratio of 1.9 - 2.6. It has been found that the lower the boron doping level, the lower the O / Si atomic ratio.

[0036] According to one embodiment of the present invention, the boron-doped silicon oxide coating of the present invention is particularly carbon-free. The absence of carbon is particularly interesting for reducing the absorption rate of the layer and may help reduce the number of defects that occur during the thermal strengthening of the coated product. The presence of carbon is a major drawback of sol-gel coatings and is further associated with the complexity of integrating the sol-gel coating process into a multi-layer coating process.

[0037] For the purposes of the present invention, if no carbon signal exceeding the carbon signal noise is detected by either X-ray fluorescence spectrometry or secondary ion mass spectrometry signals, the layer is considered carbon-free. It should be noted that surface contamination that occurs naturally on the coating when exposed to free air, particularly carbon, is ignored during analysis.

[0038] The boron-doped silicon oxide top layer of any of the above embodiments, or a combination of embodiments, can be advantageously deposited using plasma-enhanced chemical vapor deposition (PECVD), particularly a linear plasma source such as a hollow cathode plasma source. By operating under vacuum, PECVD can be easily integrated into a vacuum multi-layer coating line such as a magnetron sputtering line.

[0039] In one embodiment, the present invention relates to a method of depositing a multilayer coating including a boron-doped silicon oxide protective layer on a glass substrate, the protective layer containing Si, O, B, the boron content being 4-12 atomic %, containing OH groups, and including the following steps: a. Providing a glass substrate b. Providing a hollow cathode linear plasma source having a length and including at least one pair of electrodes connected to an AC, DC or pulsed DC power source for depositing the protective layer on the substrate, the at least one pair of electrodes including at least one pair of hollow cathode plasma generating electrodes c. Injecting a plasma generating reactive gas containing oxygen into the electrodes of the plasma source at a flow rate of 125-750 sccm per linear meter of the length of the plasma source d. Applying power to the plasma source at a power of 10-50 kW per linear meter of the length of the plasma source to generate a plasma e. Injecting a precursor gas containing boron, silicon and hydrogen at a flow rate of 500-2500 sccm per linear meter of the length of the plasma source, injecting the precursor gas between at least the electrodes of each pair of electrodes of the plasma source, and depositing a protective layer on the glass substrate by exposing the substrate to the plasma of the plasma source

[0040] Standard cubic centimeter per minute (sccm) is a flow rate measurement unit indicating cubic centimeter per minute (cm 3 / min) under standard conditions of temperature and pressure for a given fluid. These standard conditions are fixed at a temperature of 0 °C (273.15 K) and a pressure of 1.01 bar in the present invention.

[0041] According to one embodiment of the present invention, the multilayer coating further includes one or more layers deposited, for example, by magnetron sputtering and / or PECVD. Optionally, additional coatings may be deposited by the same technique, for example, after deposition of the protective layer. Thereby, a multilayer coating as described above including a boron-doped silicon oxide layer for protection can be formed.

[0042] In step b) of the process of the present invention, a low-pressure PECVD plasma source is required, and the pressure is preferably 0.13 - 66.66 Pa (0.001 - 0.5 Torr), preferably 0.13 - 4.00 Pa, more preferably 0.40 - 2.67 Pa. This apparatus is provided with a hollow cathode linear plasma source including at least one pair of electrodes, and this pair of electrodes is usually connected to an AC, pulsed DC generator or DC generator with a frequency of 5 - 150 kHz, preferably 5 - 100 kHz. The pressure is maintained by a vacuum pump.

[0043] An example of a PECVD apparatus will be described below. The PECVD source is connected to a vacuum chamber or provided within the vacuum chamber. This vacuum chamber is arranged such that a plurality of PECVD apparatuses or other deposition sources having different deposition forms can be arranged adjacent to each other within the same vacuum chamber or within a separately connected vacuum chamber. For specific applications, these other deposition sources enabling different deposition forms are flat cathodes or rotating cathodes for magnetron sputtering deposition. The deposition sources are selected and combined within a coater to provide a deposition process for a multilayer coating including the protective layer of the present invention, particularly on a glass substrate having dimensions up to at least 3.2 x 6 m 2 in order to provide a deposition process on a glass substrate having dimensions up to 3.2 x 6 m.

[0044] The vacuum chamber may be part of a horizontal coater or a vertical coater, and may further be provided with a transfer chamber.

[0045] The linear plasma source is particularly useful for depositing a uniform layer on a large substrate in a dynamic or continuous coating process. The linear plasma source is arranged perpendicular to the moving direction of the substrate and extends longitudinally across the width of the substrate. The advantage of the linear plasma source is scalability. The length of the linear plasma source can be adjusted to cover substrates of different widths, and the applied power, gas flow rate and precursor flow rate are adjusted in proportion to the length. The width of the linear plasma source extends parallel to the moving direction of the substrate. The showerhead type plasma source or point plasma source is 1 x 1 m 2It is not very suitable for large substrates exceeding this size. This is because coating such large substrates requires a complex arrangement such as an array of multiple sources, and it is difficult to achieve uniformity.

[0046] The "hollow cathode type plasma source" is construed to mean a plasma source or ion source including one or more electrodes configured to generate a hollow cathode discharge. An example of a hollow cathode type plasma source is described in U.S. Patent No. 8,652,586, the entire description of which is incorporated herein by reference. FIG. 1 shows a hollow cathode type plasma source that can be used in the present invention. The plasma source includes at least a pair of hollow cathode electrodes (1, 2) arranged in parallel and connected via an AC power source (not shown). An electrical insulating material (3) is disposed around the hollow cathode electrodes. The plasma generating gas is supplied through inlets (4) and (5). The precursor gas is supplied through the precursor gas inlet (6) and led from the dark space between the electrodes to the plasma curtain (9) through the manifold (7) and the precursor injection slots (8). The AC power source supplies a changing bipolar voltage or an alternating bipolar voltage to the two electrodes. The AC power source first drives the first electrode to a negative voltage to form plasma and drives the second electrode to a positive voltage to function as the anode of the voltage application circuit. Next, the first electrode is driven to a positive voltage to reverse the roles of the cathode and anode. When one of the electrodes is driven negatively, discharges (1a, 2a) are formed in the corresponding cavities. Next, the other electrode forms the anode, and electrons move from the plasma through the outlets (1b, 2b) to the anode side, completing the electrical circuit. As shown in FIG. 2, a linear plasma (9) having a curtain shape is formed in the region between the first electrode and the second electrode on the substrate (10). This method of driving the hollow cathode with AC power contributes to the formation of a uniform linear plasma spreading over the entire substrate (10). The length (L12) of the plasma source is perpendicular to the moving direction (T) of the substrate, and the width (W12) of the plasma source is parallel to the moving direction (T) of the substrate.

[0047] In a hollow cathode linear plasma source, it is possible to generate a uniform plasma without relying on a closed-loop electron drift. "Closed-loop electron drift" means an electron flow generated by intersecting electric and magnetic fields. In many conventional plasma forming devices, a closed-loop circulation path or "race track" of the electron flow is formed by the closed-loop electron drift.

[0048] "AC power" means power from an AC power source in which the voltage changes at a constant frequency in the form of a sine wave, square wave, pulse, or other waveform. The change in voltage often varies from negative to positive, i.e., with respect to ground. In the bipolar format, the power output supplied by two lead wires is usually out of phase by about 180°.

[0049] An "electrode" provides free electrons during plasma generation, for example while connected to a power source that supplies voltage. The electron emission surface of the hollow cathode is regarded as one electrode in combination. Electrodes can be made from materials well known to those skilled in the art, such as steel, stainless steel, copper, aluminum, etc. However, these materials need to be carefully selected for each plasma-enhanced process because different electrode materials may be required depending on the gas to ignite and maintain the plasma during operation. The performance and / or durability of the electrode can also be improved by coating the electrode.

[0050] In the case of any plasma source of the present invention, the power density of the plasma is defined as the power consumed by the plasma generated at the electrode, based on the size of the plasma. In a hollow cathode linear plasma source, the "power density of the plasma" can be defined as the total power applied to the plasma source divided by the total length of the plasma source.

[0051] The "linear meter of plasma length" refers to the length of the plasma defined as the distance between both ends of the plasma generated by a pair of electrodes in a direction transverse to the moving direction of the substrate to be coated. When the plasma source includes a plurality of electrode pairs, the plasma length is defined as the sum of the distances between both ends of the plasma generated by each electrode pair in a direction transverse to the moving direction of the substrate to be coated. As can be well understood by those skilled in the art, these hollow cathode linear plasma sources are scalable in that the length can be adjusted to span the width of the substrate to be processed. The length of the plasma source may be, for example, several meters. Therefore, it is reasonable to express the flow rate and the applied power in units that depend on the overall length of the plasma source. For example, to double the length of the plasma source, it is necessary to double the applied power and the flow rate.

[0052] The meanings of the terms used in the original text described in English are as follows. The "a", "an", and "the" used in the original text described in English refer to both the singular and plural forms unless the context clearly indicates otherwise. For example, "a chamber" refers to one or more chambers.

[0053] As used in the specification, "Comprise", "comprising", "comprises", and "comprised of" are synonymous with "include", "including", "includes", "contain", "containing", and "contains", and are inclusive or open-ended terms that, for example, identify the presence of subsequent items such as components, and do not exclude or preclude the presence of additional components, functions, elements, members, or steps known in the art, disclosed, or not described.

[0054] The description of a numerical range by endpoints includes not only the described endpoints but also all numerical values and fractions included in that range.

[0055] The pair of electrodes that form the cavity where plasma discharge occurs are each connected to a pipe for introducing a reactive plasma generating gas, and are provided with an opening through which the ionized gas, i.e., plasma, is discharged.

[0056] The frequency of the power supply connected to the electrodes is 5 - 150 kHz, preferably 5 - 100 kHz.

[0057] At least one pair of electrodes of the linear plasma source may have a length of 250 mm - 4000 mm and a width of 100 mm - 800 mm.

[0058] Such values have the advantage of ensuring an amount of reactive gas that is sufficiently more than the amount of the precursor, and it becomes possible to control and / or avoid the incorporation of carbon into the layer. The applied power, the flow rates of the reactive gas and the precursor are adjusted in proportion to the length of the linear plasma source.

[0059] The power supply preferably supplies power between 5 kW - 50 kW per linear meter of the length of the plasma source, and advantageously between 10 kW - 35 kW per linear meter of the length of the plasma source. When the power is less than 5 kW per linear meter of the length of the plasma source, carbon is observed to be present in the protective layer, and when it exceeds 50 kW per linear meter of the length of the plasma source, the formation of arcs that can have an adverse effect on the life of the plasma source and the quality of the coating may be observed.

[0060] The reactive gas contains oxygen or an oxygen-containing derivative, and the latter is preferably selected from the group consisting of ozone, hydrogen peroxide, water and CO2. According to an embodiment, the reactive gas can more advantageously further contain an inert gas such as helium, nitrogen, argon, neon or krypton in order to promote the chemical dissociation of the precursor and control the ion impact by the ion source. When present, the proportion of the inert gas in the reactive gas is 2% - 50% by volume, preferably 3% - 10% by volume, more preferably 4% - 7% by volume. This selection makes it possible to control the coverage rate of the resulting layer.

[0061] The reactive gas is preferably O2 or an O2-Ar mixture.

[0062] In one embodiment of the present invention, the flow rate of the reactive gas is 2000 - 5000 sccm per linear meter of the plasma source length.

[0063] The precursor gas containing boron, silicon, and hydrogen is uniformly injected into the plasma along the length of the plasma source. The precursor is injected, for example, between the electrodes of an electrode pair or, when there are multiple electrode pairs, between adjacent electrode pairs. This precursor gas is activated by this plasma. The substrate is moved close to the deposition source, and a thin layer is deposited on the substrate from the activated gas.

[0064] The flow rate of the precursor gas is preferably 125 - 750 sccm per linear meter of the plasma source length. Generally, when the precursor gas is a mixture of precursors, the flow rate of the precursor gas is the sum of the flow rates of the precursors in the mixture.

[0065] The distance between the substrate surface and the opening of the plasma source (the opening from which the plasma is emitted from the plasma source) is preferably at least 2.0 - 20 cm, more preferably at least 4 - 15 cm.

[0066] Preferably, the ratio of the reactive gas flow rate to the precursor gas flow rate is at least 3, and advantageously 3 - 50.

[0067] The precursor gas contains silicon, boron, and hydrogen, and may particularly further contain carbon and / or oxygen.

[0068] The precursor gas may contain a single precursor or a mixture of different precursors with different compositions. The ratio of the precursors is adjusted so as to set the boron doping to a desired level, particularly adjusted so that the boron content in the boron-doped silicon oxide layer is 4 - 12 atomic %.

[0069] According to one embodiment of the present invention, the precursor gas includes at least one precursor containing Si, at least one precursor containing B, and / or at least one precursor containing Si and B. Any of the precursors in the precursor gas may further contain hydrogen. Any of the precursors in the precursor gas may further contain carbon. Any of the precursors may further contain oxygen.

[0070] The temperature reached by the substrate during the deposition of the protective layer is 20°C - 60°C depending on the residence time of the substrate in the plasma, for example, the moving speed of the substrate under the plasma source.

[0071] In one embodiment of the present invention, the precursor containing boron-free silicon, that is, the precursor not containing boron, is preferably represented by the following formula (I), (II), (III), (IV) or (V).

[0072] Y1-X-Y2 ··· Formula (I) -[Si(CH3) q (H) 2-q -X-] n - ··· Formula (II) CH2=C(R1)-Si(R2)(R3)-R4 ··· Formula (III) R5-Si(R6)(R7)-R8 ··· Formula (IV) CH2=C(R9)C(O)-O-(CH2) p -Si(R 10 )(R 11 )-R 12 ··· Formula (V) In Formula (I), X is O or NH, Y1 is -Si(Y3)(Y4)Y5, Y2 is Si(Y 3' )(Y 4' )Y 5' where Y3, Y4, Y5, Y 3' , Y 4' and Y 5' are each independently H or an alkyl group having up to 10 carbon atoms, where at most one of Y3, Y4 and Y5 is hydrogen, and Y 3' , Y 4' and Y 5'At most one of them is hydrogen, and the total number of carbon atoms is 20 or less. Formula (II) is cyclic, n is 2 - 10, q is 0 - 2, and the total number of carbon atoms is 20 or less. In formula (III), R1 is H or an alkyl group, such as -CH3, and R1, R2, and R3 are each independently H, an alkyl group having up to 10 carbon atoms, or an alkoxy group -O-Z, where Z is preferably -C t H 2t+1 and t is 1 - 10. In formula (IV), R5 is H or an alkyl group, such as -CH3, and R6, R7, and R8 are each independently H, an alkyl group having up to 10 carbon atoms, or an alkoxy group -O-Z, where Z is preferably -C t H 2t+1 and t is 1 - 10. In formula (V), R9 is H or an alkyl group, such as -CH3, p is 0 - 10, and R 10 、R 11 and R 12 are each independently H, an alkyl group having up to 10 carbon atoms, or an alkoxy group -O-Z, where Z is preferably -C t H 2t+1 and t is 1 - 10.

[0073] The alkyl group may be linear or branched, but a linear group is preferred. Such an alkyl group is suitably a methyl group or an ethyl group, and a methyl group is preferred. Y3, Y4, Y5, Y 3' 、Y 4' and Y 5' are all alkyl groups.

[0074] The alkoxy group may be linear, branched, or cyclic, but a linear group is preferred. Such an alkoxy group is suitably a methoxy group or an ethoxy group.

[0075] The silicon-containing precursor of formula (I) may contain six methyl groups. The silicon-containing precursor of formula (I) is suitably hexamethyldisiloxane (HMDSO), hexamethyldisilazane, or tetramethyldisiloxane (TMDSO).

[0076] The silicon-containing precursor of formula (II) may be one where n is 3, n is 4, n is 5 or n is 6. Appropriately, the silicon-containing precursor of formula (II) is octamethylcyclotetrasiloxane. Appropriately, the silicon-containing precursor of formula (II) is hexamethylcyclotrisilazane.

[0077] For the silicon-containing precursor of formula (V), p is 2, and each of R 10 , R 11 and R 12 may each be an alkoxy group, such as methoxy. Appropriately, the silicon-containing precursor of formula (V) is 3-(trimethoxysilyl)propyl methacrylate. Appropriately, the silicon-containing precursor of formula (V) is 3-(trimethoxysilyl)propyl acrylate.

[0078] In one embodiment of the present invention, the boron-containing precursor free of silicon, i.e., the precursor not containing silicon, is preferably represented by the following formula (VI).

[0079] R 13 -B(R 14 )(R 15 ) ··· Formula (VI) R 13 , R 14 and R 15 are each independently, each independently, H, an alkyl group having up to 10 carbon atoms or an alkoxy group -O-Z, where Z is preferably -C t H 2t+1 and t is 1 - 10.

[0080] The alkyl group may be linear or branched, but a linear group is preferred. As such an alkyl group, a methyl group or an ethyl group is suitable, and a methyl group is preferred.

[0081] The alkoxy group can be linear, branched or cyclic, but a linear group is preferred. As such an alkoxy group, a methoxy group, an ethoxy group or an isopropoxy group is suitable.

[0082] In one embodiment of the present invention, in formula (VI), R 13 , R 14 and R 15 are all ethoxy groups or all isopropoxy groups.

[0083] In one embodiment of the present invention, the precursor containing boron and silicon is of formula (VII).

[0084] R 16 O-B(-OR 17 )(-OR 18 ) ··· Formula (VII) R 16 , R 17 and R 18 are all independently an organosilyl group, particularly a trialkylsilyl group, that is, an alkyl group having up to 10 carbon atoms. Suitable such trialkyl groups include a trimethylsilyl group, a triethylsilyl group, or a diethyl(methyl)silyl group. A suitable precursor containing such boron and silicon is tris(trimethylsilyl)borate (TTMSB).

[0085] Preferably, the precursor containing boron, silicon, and / or both silicon and boron is transported to the plasma source without using a carrier gas. However, in some embodiments, an additional gas can be used as a carrier gas to introduce the precursor into the plasma chamber.

[0086] Preferably, any precursor is supplied as a liquid and then vaporized and transported to the plasma source in its vaporized state. Preferably, any vaporized precursor is transported to the plasma chamber without using a carrier gas. Alternatively, if necessary, the liquid precursor supply system uses a carrier gas to transport the vaporized precursor to the plasma chamber.

[0087] Preferably, when a carrier gas is used, the carrier gas is selected from N2, He, or Ar, and / or any mixture of these gases. In one preferred process, a single carrier gas is used. Most preferably, it is He or Ar.

[0088] Preferably, when a carrier gas is used, the amount of the carrier gas is about 5% - about 1500% carrier gas based on the total flow rate of all silicon- and boron-containing precursors, preferably about 10% - about 1000% additional gas, more preferably 20% - 750%, such as 25% - 500%, such as 500, 450, 400, 350, 300, 250, 200, 175, 150, 125, 100, 90, 80, 75, 70, 60, 50, 40, 35, 30, or 25% carrier gas.

[0089] Any precursor may be a gas at room temperature and atmospheric pressure or a vaporized liquid.

[0090] To obtain a high dynamic deposition rate of about 20 - 500 nm.m / min, the following various precursor flow rates are required. Generally, the higher the precursor flow rate, the higher the power supplied to the plasma source.

[0091] In one embodiment of the present invention, the total flow rate of the silicon-containing precursor is 10 - 500 sccm (standard cubic centimeters per minute) per linear meter of the plasma length, preferably 50 - 500 sccm or 50 - 400 sccm per linear meter of the plasma length.

[0092] In this application, the unit "nm.m / min" is used to represent the deposition rate. This unit is a combination of SI units commonly used to represent the deposition rate in a dynamic or continuous coating process, i.e., a process in which the substrate moves continuously within the deposition apparatus. The deposition rate of such a deposition apparatus is generally referred to as the "dynamic deposition rate (DDR)" and is used to represent the deposition rate of the coating apparatus itself regardless of the speed at which the substrate moves within the deposition apparatus.

[0093] In one embodiment of the present invention, the total flow rate of the boron-containing precursor is 10 - 500 sccm (standard cubic centimeters per minute) per linear meter of the plasma length, preferably 50 - 500 sccm or 50 - 400 sccm per linear meter of the plasma length.

[0094] In one embodiment of the present invention, the total flow rate of the silicon- and boron-containing precursor is 10 - 750 sccm (standard cubic centimeters per minute) per linear meter of the plasma length, preferably 50 - 750 sccm or 50 - 600 sccm per linear meter of the plasma length.

[0095] In some cases, step c) can further include applying an additional precursor to the substrate to include certain additional oxides such as titanium oxide or zirconium oxide, further improving mechanical and / or chemical durability, and / or increasing the refractive index of the boron-doped silicon oxide protective layer.

[0096] According to one embodiment of the present invention, the boron-doped silicon oxide protective layer contains at least 80 wt% silicon dioxide SiO2.

[0097] According to one embodiment of the present invention, the boron-doped silicon oxide protective layer contains up to 15 wt% titanium oxide, zirconium oxide, or a mixture thereof.

[0098] The present invention is defined by the independent claims, and the preferred embodiments are defined by the dependent claims.

[0099] It should be noted that the present invention relates to any possible combination of the features described in the claims or the above embodiments.

Examples

[0100] A boron-doped silicon oxide protective layer was deposited as the top layer of various glass substrates to form a multi-layer coated glass substrate.

[0101] Substrate A is a normal transparent soda-lime glass substrate with a thickness of 4 mm and has the following layer sequence (Table 1) numbered from the glass surface before adding the boron-doped silicon oxide protective layer. These layers were deposited using magnetron sputtering.

[0102]

Table 1

[0103] ZnO:Al is a zinc oxide layer doped with aluminum and contains 2-10% aluminum by weight.

[0104] Ti x Zr y O z represents a mixed oxide of titanium and zirconium and is composed of 65% titanium oxide and 35% zirconium oxide by weight.

[0105] The precursors used for the deposition of the protective layer are shown in Table 2 below. Inside the vacuum chamber, the glass substrate was conveyed at a continuous speed in a direction perpendicular to the length of the PECVD source on a roller conveyor under the PECVD source. The glass substrate may pass under the PECVD source multiple times to achieve the intended layer thickness (number of passes).

[0106] The PECVD source used is composed of two sets of electrodes, each 40 cm long, arranged perpendicular to the direction of substrate movement. As a result, the total length of the plasma is 80 cm. This plasma source is supplied with 16 kW of power, and the supplied power is 16 kW / 0.8 m = 20 kW per linear meter of the plasma source length. The flow rate of the O2 reactive gas is adjusted to reduce the amount of carbon in the coating to a level where it cannot be detected. The deposition parameters are shown in Table 3 below.

[0107]

Table 2

[0108] Before depositing the protective layer, the substrate was treated with oxygen plasma using the same PECVD source. The O2 flow rate was 2000 sccm and the applied power was 12.5 kW / m. Example 0 is Comparative Substrate A without the protective layer deposited. Examples 1, 2, 9, and 10 are comparative samples coated with a silicon oxide layer without boron doping. Examples 3 - 6 and 11 show the possibility of deposition using the precursor mixture. Examples 7 and 8 were carried out using a single precursor.

[0109]

Table 3

[0110] Table 4 shows the dynamic deposition rates (DDR) obtained for various examples, refractive indices, boron contents, and thicknesses. Such deposition rates are significantly higher than those obtained by magnetron sputtering.

[0111]

Table 4

[0112] X-ray fluorescence spectrometry was used to determine the B atom content in the boron-doped silicon oxide layer. To determine the carbon content, the same coating was deposited on a silicon substrate and the FTIR (Fourier transform infrared spectrometry) spectrum was measured. No carbon bonds were detected.

[0113] Neutral salt spray test (NSST) - This test is carried out by exposing the sample to salt spray formed by spraying an aqueous solution containing 50 g / l of sodium chloride in a chamber maintained at 35 °C for at least 5 days, or at least 10 days, or at least 21 days (the details of this test are described in the international standard ISO9227 - 1990).

[0114] The Cleveland test (Clev) is carried out in accordance with the ISO 6270-1:1998 standard for at least 2.0 days, 5 days, 10 days or 15 days.

[0115] Environmental chamber test (CC) - This test is performed by placing the sample in a chamber filled with an H2O atmosphere and subjecting it to a 2-hour temperature cycle. In this cycle, the temperature changes from 45°C to 55°C and then back to 45°C. This cycle continues for at least 2.0 days, 5 days, 10 days or 21 days. CC BB is a test carried out before the heat treatment (before baking) of the glass plate, and CC AB is a test carried out after the heat treatment (after baking) of the glass plate.

[0116] The results of each of the above tests are obtained by visually evaluating the sample compared to the scale of a defined reference sample. The scales for the Cleveland, environmental chamber, and salt spray tests are based on an internal scale from 0 to 5, where 0 corresponds to a reference sample with significant deterioration (pixels, deep points, stretch marks, etc.). A value of 5 corresponds to a complete or almost complete surface with no signs of deterioration. Intermediate values (up to 0.25 units) correspond to samples with different levels of deterioration on the internal scale and are ranked in order of the level of deterioration. The acceptable values are 3 - 5.

[0117] Table 5 below shows the results of various tests. Some samples were tested before and after heat treatment. Heat treatment is carried out by placing the sample in a convection furnace at a temperature of 670°C for 4 - 5 minutes.

[0118]

Table 5

[0119] In Examples 1 and 2 containing silicon oxide without boron doping, some improvement is observed before heat treatment, but the performance is clearly lower than that of Examples 3 - 7 containing boron-doped silicon oxide coatings.

[0120] The substrate B is a normal transparent soda-lime glass substrate with a thickness of 4 mm, and has the following layer sequence (Table 5) numbered in order from the glass surface by magnetron sputtering. Next, according to the conditions in Table 6, various protective layers of boron-doped silicon oxide were added by PECVD. Next, a zirconium-doped silicon oxide layer with a thickness of 20 nm was added by magnetron sputtering. These layers were deposited using magnetron sputtering. The resulting multilayer coating is an antireflection coating. Examples 16 and 17 are comparative examples without boron doping.

[0121]

Table 6

[0122]

Table 7

[0123]

Table 8

[0124]

Table 9

[0125] Examples 16 - 19 all have substantially the same optical properties. Examples 16 and 17 without the boron-doped silicon oxide protective layer have little resistance to heat treatment and alkaline solutions respectively, while Examples 18 and 19 with the boron-doped silicon oxide protective layer show excellent resistance to both heat treatment and alkaline solutions.

Claims

1. A glass substrate having a multilayer coating including a boron-doped silicon oxide protective layer, wherein the boron-doped silicon oxide comprises Si, O, B, OH groups, such that the boron content is 4-12 atomic %, characterized glass substrate.

2. The glass substrate according to claim 1, wherein the protective layer does not contain carbon, characterized glass substrate.

3. The glass substrate according to claim 1 or 2, wherein The protective layer has an FTIR absorbance peak area ratio A of the -OH stretching vibration absorption peak area to the Si-O-Si stretching vibration absorption peak area ＯＨ / A ＳＩＯＳｉ of 0.25 - 0.5, and is a glass substrate characterized by this.

4. The glass substrate according to any one of claims 1 to 3, wherein the thickness of the protective layer is 50 nm or more and 400 nm or less, characterized glass substrate.

5. The glass substrate according to any one of claims 1 to 4, wherein the refractive index of the protective layer at a wavelength of 633 nm is 1.4 - 1.5, characterized glass substrate.

6. The glass substrate according to any one of claims 1 to 5, wherein The protective layer contains at least 80% by weight of SiO ２ A glass substrate characterized by including the same.

7. The glass substrate according to any one of claims 1 to 6, wherein the protective layer contains up to 15% by weight of titanium oxide, zirconium oxide, or a mixture of titanium oxide and zirconium oxide, characterized glass substrate.

8. The glass substrate according to any one of claims 1 to 7, wherein the protective layer is essentially composed of Si, B, O, and H, characterized glass substrate.

9. The glass substrate according to any one of claims 1 to 8, wherein the multilayer coating is selected from an antireflection coating, an ultraviolet reflection coating, an insulating low-emissivity coating, and a solar control coating, characterized glass substrate.

10. A process of depositing a boron-doped silicon oxide layer for protection, which contains Si, O, and OH groups and has a boron content of 4-12 atomic %, on a glass substrate, comprising providing a glass substrate; providing a hollow cathode linear plasma source having a length and including at least one pair of electrodes connected to an AC, DC, or pulsed DC power source for depositing the protective layer on the substrate; injecting a reactive gas for plasma generation containing oxygen into the electrodes of the plasma source at a flow rate of 125 - 750 sccm per linear meter of the length of the plasma source; applying a power of 10 - 50 kW per linear meter of the length of the plasma source to the plasma source Inject a precursor gas at a flow rate of 500 - 2500 sccm per linear meter of the plasma source length, inject the precursor gas at least between the electrodes of each pair of electrodes of the plasma source, and deposit a protective layer on the glass substrate by exposing the substrate to the plasma of the plasma source. A process characterized by including the above. **Claim 11** The process according to claim 10, wherein the precursor gas includes at least one precursor containing Si, at least one precursor containing B, and / or at least one precursor containing Si and B. **Claim 12** The process according to claim 10 or 11, The reactive gas is O ２ or an O ２ -Ar mixture, characterized by the process. **Claim 13** [[ID=,8]]The process according to any one of claims 10 to 12, wherein the flow rate of the reactive gas is 2000 - 5000 sccm per linear meter of the plasma source length. **Claim 14** The process according to any one of claims 10 to 13, wherein the precursor gas includes at least one precursor selected from a precursor containing silicon, a precursor containing boron, and / or a precursor containing silicon and boron, and the total flow rate of each of the precursors is 10 - 500 sccm.

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