Boron-doped silicon oxide protection layer and manufacturing method thereof

Abstract

The invention relates to a glass substrate (10) with a multilayer coating comprising a protective layer (P) of a boron-doped silicon oxide, the boron-doped silicon oxide comprising Si, O, B, and OH groups, and the boron content being between 4 at% and 12 at%. The invention further comprises a method for depositing a boron-doped silicon oxide layer on a glass substrate by means of PECVD of the linear hollow cathode type, said boron-doped silicon oxide layer comprising Si, O, B, and OH groups, and wherein the boron content is between 4 at% and 12 at%.

Description

Technical Field

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

[0002] The multi-layer coating provides a variety of properties to the coated glass substrate, and may provide, among other things, solar control properties, insulating properties, anti-reflective properties, and / or bird strike protection properties.

[0003] Such coatings are typically deposited using magnetron sputtering and may include, for example, a dielectric layer, a transparent conductive oxide layer, and a metal layer. Such coatings are subject to mechanical and chemical stresses during handling, transportation, and processing into finished windows. During these steps, the multilayer coating is exposed to conditions that may lead to corrosion of the coating, resulting in defects such as point defects or even delamination.

[0004] In the field of glazing, several protective coatings for glass substrates are known. These protective coatings are usually used to provide magnetron sputtering coatings with additional resistance to different mechanical and / or chemical attacks.

[0005] For example, EP2262745A1 describes a glass substrate with a solar control or low-emissivity (low E) insulating coating with a protective top layer based on titanium oxide and additional oxides of ZrO2, SiO2 or Cr2O3. The protective top layer provides mechanical and chemical durability; however, the refractive index of these coatings is very high, typically at least 2.0 at a wavelength of 633 nm. Such high refractive index layers tend to increase the reflectance of the resulting coating stack, especially at higher thicknesses, which is undesirable in many applications, and therefore their thickness is limited.

[0006] WO03068500A1 discloses protective top layers with a lower refractive index made of mixed oxides of aluminum and silicon. However, these protective top layers are not economically attractive because their deposition rates are very low. In addition, it was found that these protective top layers have insufficient resistance to mechanical and chemical degradation.

[0007] EP2857370A1 discloses plasma enhanced chemical vapor deposited SiO2 layers having a good deposition rate and good resistance to heat treatment. However, it has been found that the chemical resistance of these layers still needs to be improved.

[0008]

[0006] Therefore, there is a need in the art for layers that increase the resistance of multilayer coatings to chemical degradation and that have a low refractive index and can be deposited at high deposition rates. Summary of the invention

[0009] It is an object of the present invention to provide a glass substrate with a multilayer coating comprising a protective layer which provides the coated substrate with increased chemical resistance and which preferably has a low refractive index in the visible range.

[0010] Therefore, the present invention relates to a glass substrate with a multilayer coating, which includes a protective layer of boron-doped silicon oxide, wherein the boron-doped silicon oxide contains Si, O, B, and OH groups and wherein the boron content is between 4 atomic % and 12 atomic %.

[0011] Another object of the present invention is to provide a method for depositing a boron-doped silicon oxide protective layer, wherein the boron-doped silicon oxide contains Si, O, B, and OH groups, and wherein the boron content is between 4 atomic % and 12 atomic %.

[0012] In certain embodiments of the present invention, a method for depositing a boron-doped silicon oxide protective layer (comprising Si, O, B, and OH groups, and wherein the boron content is between 4 atomic % and 12 atomic %) on a glass substrate comprises:

[0013] a. Providing a glass substrate,

[0014] b. providing a linear hollow cathode type plasma source, the length of which includes at least one pair of hollow cathode plasma generating electrodes, and the plasma source includes at least one electrode pair connected to an AC, DC or pulsed DC generator power supply for depositing the protective layer on the substrate,

[0015] c. injecting a plasma containing oxygen into the electrode of the plasma source to generate a reactive gas at a flow rate of 125 sccm to 750 sccm per meter of plasma source length,

[0016] d. applying an electric power of 10 kW to 50 kW per meter of plasma source length to the plasma source, and

[0017] e. injecting a precursor gas at a flow rate of 500 sccm to 2500 sccm per linear meter of plasma source length, wherein the precursor gas is injected into the plasma at least between the electrodes of each electrode pair of the plasma source, and depositing the protective layer on the glass substrate by exposing the substrate to the plasma of the plasma source. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] For a more complete understanding of the nature of the present invention, reference is made to the following detailed description in conjunction with the accompanying drawings, in which:

[0019] Figure 1 Shown is a cross section of a hollow cathode type linear plasma source comprising an electrode pair for depositing the protective layer of the present invention.

[0020] Figure 2 A deposition cross-sectional view of a hollow cathode type linear plasma source is shown for continuously depositing the protective layer of the present invention relative to a substrate.

[0021] Figure 3 and Figure 4 Two different embodiments of a glass substrate with a multilayer coating comprising a protective layer of boron-doped silicon oxide are shown. DETAILED DESCRIPTION

[0022] A multilayer coating is a coating comprising two or more thin layers. A thin layer is a layer having a thickness of at most 1 μm. A multilayer coating provides improved optical and / or energy properties to a glass substrate.

[0023] In certain embodiments of the present invention, the coating is selected from anti-reflective coatings, ultraviolet (UV) reflective coatings for preventing bird collisions, insulating low-emissivity coatings, and solar control coatings. In certain embodiments of the present invention, the boron-doped silicon oxide layer is a protective top layer in a coating disposed on a substrate, i.e., the last layer or topmost layer of the multilayer coating that is farthest from the substrate. The boron-doped silicon oxide layer of the present invention can be used alternately in other positions in the sequence of layers constituting the multilayer coating.

[0024] In embodiments of the invention, the protective layer may have a refractive index of 1.4 to 1.8 at a wavelength of 633 nm, and / or may contain at least 80 wt. % SiO 2. In a multilayer coating, a thicker, lower refractive index layer may replace a thinner, higher refractive index layer; a multilayer coating may benefit from the improved protection of a thicker protective layer.

[0025] In certain embodiments of the invention, the coating is an antireflective coating comprising a high refractive index layer and a low refractive index layer in an alternating order, wherein the boron-doped silicon oxide layer is one of the low refractive index layers, preferably a protective top layer. The low refractive index layer may have a refractive index of 1.4 to 1.8 at a wavelength of 633 nm, and may be a layer comprising at least 80% by weight of SiO2. The high reflective layer may have a refractive index of at least 2.0 at a wavelength of 633 nm, and may be, for example, selected from a layer comprising a mixed nitride of titanium oxide or mixed titanium zirconium oxide, niobium oxide, silicon and zirconium. Therefore, the visible light reflectance of the substrate of the antireflective coating is lower than that of the uncoated substrate.

[0026] Figure 3A glass substrate (10) is shown 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.

[0027] In certain embodiments of the present invention, the coating is a UV reflective coating, such as a bird-proof collision coating, wherein the boron-doped silicon oxide layer is a low refractive index layer, preferably a protective top layer. Such UV reflective coatings typically include high refractive index layers and low refractive index layers in an alternating order. The low refractive index layer may have a refractive index of 1.4 to 1.8 at a wavelength of 633 nm and may be a layer comprising at least 80% by weight of SiO2. The high reflective layer may have a refractive index of at least 2.0 at a wavelength of 633 nm and may be selected, for example, from a layer comprising titanium oxide or mixed titanium zirconium oxide, niobium oxide, a mixed nitride of silicon and zirconium. Thus, the UV light reflectance of the UV reflective coated substrate is higher than that of the uncoated substrate.

[0028] In an embodiment, the present invention relates to a multilayer coating comprising n functional layers reflecting infrared radiation and n+1 dielectric coatings, wherein n≥1 and each functional layer is surrounded by a dielectric coating. The dielectric coating may include one or more dielectric layers selected, for example, from the following: layers of metal or silicon oxides, nitrides or oxynitrides, or mixtures thereof, and / or a boron-doped silicon oxide protective layer of the present invention. For example, one or more dielectric layers may be selected from mixed zinc tin oxide, silicon nitride, mixed tin antimony oxide, zinc oxide, titanium oxide, mixed titanium zirconium oxide. In particular, the topmost layer farthest from the substrate may be a boron-doped silicon oxide protective layer of the present invention.

[0029] Multilayer low-emissivity insulating coatings typically include a single functional layer that reflects infrared radiation, while multilayer coatings with low emissivity and anti-solar properties typically include two or three functional layers that reflect infrared radiation. Preferably, the functional layer that reflects infrared radiation in the multilayer coating of the present invention is a silver-based layer, which is composed of silver or silver doped with, for example, palladium or gold in a proportion of up to 5% by weight, preferably about 1% by weight. Incorporating a small amount of such dopants into the silver-based layer can improve the chemical durability of the coating stack. In an advantageous embodiment, the functional layer has a thickness of at least 6nm or at least 8nm, preferably at least 10nm; the thickness of the functional layer is preferably at most 22nm or at most 20nm, preferably at most 18nm, or at most 16nm. Such a thickness range allows the low emissivity and / or anti-solar properties sought to be achieved while limiting the light absorption of these layers. In the case of a multilayer coating with two functional layers that reflect infrared radiation, it may be preferred that the thickness of the second functional layer (i.e., the layer farthest from the substrate) is slightly greater than the thickness of the first functional layer. As an example, the thickness of the first functional layer may be between 8 nm and 18 nm, and the thickness of the second functional layer may be between 10 nm and 20 nm.

[0030] According to an embodiment of the present invention, at least one dielectric layer above or below the functional layer comprises a layer consisting essentially of boron-doped silicon oxide. This means, for example, that in a single functional layer configuration stack, the boron-doped silicon oxide layer is present in the second upper dielectric coating or the first lower dielectric coating, and in a dual-functional layer multilayer coating, the boron-doped silicon oxide layer is present in the first, second or third dielectric coating, or in any two dielectric coatings, or in each of the three dielectric coatings.

[0031] Figure 4 A glass substrate (10) is shown with a multilayer coating comprising two silver functional layers (F1, F2), each surrounded by a dielectric layer (D1 to D6), and also comprising a boron-doped silicon oxide protective layer (P) of the present invention as the uppermost layer.

[0032] In an embodiment of the present invention, the boron-doped silicon oxide protective layer of the present invention is a layer other than a silver-based layer in a multilayer coating including an infrared reflective functional layer, such as other metal or metal alloy layers (such as Cr and NiCr alloys, or stainless steel), and a transparent conductive oxide layer (such as ITO (indium-doped tin oxide)). Example embodiments can be, for example: a first layer of titanium, zirconium and / or niobium oxide on a glass substrate, a second layer consisting of at least 85 wt. % SiO2, a third layer of indium-doped tin oxide, a fourth layer of boron-doped silicon oxide according to any embodiment described herein, and an optional fifth layer that provides further enhanced mechanical protection, such as a zirconium-doped silicon oxide layer or a mixed titanium zirconium oxide layer, a zirconium oxide layer, or a mixed silicon zirconium nitride layer.

[0033] The boron doped silicon oxide protective layers of the present invention contain OH groups. The presence of OH groups is a feature that distinguishes these coatings from magnetron sputtered coatings (which do not provide the same level of protection). To the best of the inventors' knowledge, the protective ability of the boron doped silicon oxide layers of the present invention is due at least in part to the combination of OH groups and boron doping. The presence of OH groups can be determined by Fourier transform infrared spectroscopy (FTIR) on an equivalent protective layer deposited on a silicon substrate. The presence of OH groups in the protective layer is determined by the presence of OH groups at 3300 cm -1 Up to 3500cm -1 The absorption peak corresponding to the stretching vibration of -OH can be detected by the presence of an absorption peak at the wave number of , which corresponds to the stretching vibration of -OH. Another absorption peak corresponding to the stretching vibration of Si-OH can be detected at 900cm -1 Up to 1000cm -1 However, these peaks can overlap with the more intense peaks of Si-O stretching vibrations.

[0034] In an embodiment of the present invention, -OH stretching vibration (A OH ) and Si-O-Si stretching vibration (A SiOSi )'s FTIR absorption peak area is A OH / A SiOSi The absorption peak of -OH stretching vibration appears at 3300 cm -1 Up to 3500cm -1 The absorption peak of Si-O-Si stretching vibration appears at 1080 cm -1 Up to 1090cm -1 The wave number of .

[0035] In SiO2-based coatings deposited by sputtering, some hydrogen may be present in the gas phase unintentionally, but in the coating, the FTIR absorption peak area is found to be larger than A. OH / A SiOSiLess than 0.05. In addition, SiO2-based coatings deposited by sputtering usually contain aluminum because aluminum is added to silicon sputtering targets to improve their electrical conductivity. The boron-doped silicon oxide layer of the present invention may be free of aluminum.

[0036] The boron-doped silicon oxide layer of the present invention was found to be amorphous and non-porous, as seen, for example, by transmission electron microscopy.

[0037] The boron-doped silicon oxide layer of the present invention includes, or may consist essentially of, silicon, boron, oxygen, and hydrogen.

[0038] In any of the above embodiments, the boron content of the boron-doped silicon oxide layer may be 4 to 12 atomic % B. In this doping range, the refractive index can be kept very low, i.e., 1.4 to 1.5 at a wavelength of 633 nm, in particular if the SiO2 weight content is at least 80%. At the same time, good chemical resistance of the multilayer coating is obtained, and the haze level after thermal strengthening can be kept low, in particular can be kept at values ​​below 0.3%.

[0039] The boron content in the boron-doped silicon oxide layer is preferably determined by quantitative evaluation by x-ray photoelectron spectroscopy (XPS) or by secondary ionization mass spectroscopy (SIMS) using appropriate standards.

[0040] According to an embodiment of the present invention, the boron-doped silicon oxide protective layer can have a thickness of at least 50nm, preferably at least 80nm, showing a more significant durability improvement. The thickness can be adjusted in a wide range to adjust the optical properties of the final coated product. Therefore, the thickness of the boron-doped silicon oxide layer can be at most 400nm, in particular at most 350nm, more particularly at most 300nm. Due to the slow deposition rate of silicon oxide-based coatings, such a high thickness is not suitable for magnetron sputtering deposition.

[0041] According to an embodiment of the present invention, the boron-doped silicon oxide layer of the present invention may have an O / Si atomic ratio between 1.9 and 2.6. It was found that at lower boron doping levels, the O / Si atomic ratio was lower.

[0042] According to an embodiment of the invention, the boron-doped silicon oxide coating of the invention may in particular be free of carbon. The absence of carbon is particularly interesting for reducing the absorptivity of the layer and may help reduce the number of defects that occur when the coated product is thermally strengthened. In addition to the complexity of integrating the sol-gel coating process in a multilayer coating process, the presence of carbon is also a significant disadvantage of sol-gel coatings.

[0043] For the purposes of the present invention, a layer is considered to be free of carbon when no carbon signal is detectable above the signal noise of carbon in the X-ray fluorescence spectrum or the secondary ion mass spectrometry signal. It should be noted that surface contamination, especially carbon, which is naturally present on the coating when exposed to free air should be ignored during the analysis.

[0044] The boron-doped silicon oxide top layer of any embodiment or combination of the above embodiments can be advantageously deposited using plasma enhanced chemical vapor deposition (PECVD), in particular using a linear plasma source (e.g., a hollow cathode plasma source). By operating under vacuum, PECVD can be easily integrated into a vacuum multilayer coating production line (e.g., a magnetron sputtering production line).

[0045] The present invention relates in an embodiment to a method of depositing a multilayer coating on a glass substrate, the multilayer coating comprising a boron-doped silicon oxide protective layer, wherein the protective layer comprises Si, O, B and OH groups, and wherein the boron content is between 4 atomic % and 12 atomic %, the method comprising:

[0046] a. Providing a glass substrate,

[0047] b. providing a linear hollow cathode type plasma source having a length comprising at least one pair of hollow cathode plasma generating electrodes connected to an AC, DC or pulsed DC generator power supply for depositing the protective layer on the substrate,

[0048] c. injecting a plasma containing oxygen into the electrode of the plasma source to generate a reactive gas at a flow rate of 125 sccm to 750 sccm per meter of plasma source length,

[0049] d. applying an electric power of 10 kW to 50 kW per linear meter of plasma source length to the plasma source to generate plasma, and

[0050] e. injecting a precursor gas containing boron, silicon and hydrogen at a flow rate of 500 sccm to 2500 sccm per linear meter of plasma source length, wherein the precursor gas is injected into the plasma at least between 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.

[0051] Standard cubic centimeter per minute (sccm) is a unit of flow measurement that represents the volume of a fluid at standard conditions of temperature and pressure. 3 These standard conditions apply to the present invention and are fixed at a temperature of 0° C. (273.15 K) and a pressure of 1.01 bar.

[0052] According to an embodiment of the present invention, the multilayer coating further comprises 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 the protective layer is deposited. Thus, a multilayer coating comprising a boron-doped silicon oxide protective layer as described above may be formed.

[0053] Step b) of the method of the present invention requires a low-pressure PECVD plasma source, the pressure of which is preferably between 0.13 Pa and 66.66 Pa (0.001 Torr to 0.5 Torr), preferably between 0.13 Pa and 4.00 Pa, more preferably between 0.40 Pa and 2.67 Pa, the device being provided with a hollow cathode type linear plasma source comprising at least one electrode pair connected to an AC or pulsed DC generator (whose frequency is generally between 5 kHz and 150 kHz, preferably between 5 kHz and 100 kHz), or to a DC generator. The pressure is maintained by a vacuum pump.

[0054] Examples of PECVD devices are described below. The PECVD source is connected to a vacuum chamber or is arranged in a vacuum chamber. The vacuum chamber is arranged so that it can have multiple PECVD devices or other deposition sources with different deposition forms next to each other in the same vacuum chamber or in separate connected vacuum chambers. In some applications, these other deposition sources (which allow different deposition forms) are planar cathodes or rotating cathodes for magnetron sputtering deposition. The deposition sources are selected and combined in a coating machine to provide a deposition process for a multilayer coating including a protective layer of the present invention, especially for a coating having a size of at least 3.2x6m 2 Deposition process on glass substrate.

[0055] The vacuum chamber may be part of a horizontal coater or a vertical coater and may also include a transfer chamber.

[0056] Linear plasma sources are particularly useful for depositing uniform layers on large substrates in dynamic or continuous coating processes. A linear plasma source is placed perpendicular to the direction of travel of the substrate so as to span across the width of the substrate in its longitudinal direction. The advantage of linear plasma sources is their scalability. Thus, their length can be adapted to span substrates of different widths, the applied power as well as the gas and precursor flow rates being adjusted proportionally to the length. The width of a linear plasma source extends parallel to the direction of travel of the substrate. Showerhead type plasma sources or point plasma sources are particularly less suitable for depositing uniform layers on large substrates larger than 1 x 1m 2 Large substrates that extend over large areas are often difficult to coat, as coating such large substrates requires complex arrangements, such as an array of multiple sources, and uniformity is difficult to achieve.

[0057] A "hollow cathode type plasma source" refers to a plasma or ion source comprising one or more electrodes configured to produce a hollow cathode discharge. An example of a hollow cathode plasma source is described in US8652586, the entire contents of which are incorporated herein by reference. Figure 1 A hollow cathode type plasma source that can be used in the present invention is shown. The plasma source includes at least one pair of hollow cathode electrodes (1, 2) arranged in parallel and connected by an AC power supply (not shown). An electrically insulating material (3) is arranged around the hollow cathode electrode. The plasma generating gas is supplied via an inlet (4) and an inlet (5). The precursor gas is supplied via a precursor gas inlet (6) and introduced into the plasma curtain (9) through a manifold (7) and a precursor injection slot (8) in the dark space between the electrodes. The AC power supply provides a varying or alternating bipolar voltage to the two electrodes. The AC power supply initially drives the first electrode to a negative voltage, allowing plasma to form, and drives the second electrode to a positive voltage to serve as the anode of the voltage application circuit. This then drives the first electrode to a positive voltage and reverses the role of the cathode and anode. When one of the electrodes is driven negative, a discharge (1a, 2a) is formed in the corresponding cavity. The other electrode then forms an anode, allowing electrons to escape the plasma through an outlet (1b, 2b) and travel to the anode side, thereby completing the circuit. Therefore, as Figure 2 As shown, a linear plasma (9) having a curtain shape is formed in the region between the first electrode and the second electrode above the substrate (10). This method of driving the hollow cathode with an AC power source helps to form a uniform linear plasma across the substrate (10), the length (L12) of the plasma source is perpendicular to the traveling direction (T) of the substrate, and the width (W12) of the plasma source is parallel to the traveling direction (T) of the substrate.

[0058] In a linear hollow cathode type plasma source, a uniform plasma can be generated without relying on closed-circuit electron drift. "Closed-circuit electron drift" refers to the electron flow caused by crossed electric and magnetic fields. In many conventional plasma forming devices, closed-circuit electron drift forms a closed loop path or "racetrack" for electron flow.

[0059] "Alternating current (AC)" refers to electrical power from an alternating current source in which the voltage varies at some frequency in a sinusoidal, square wave, pulsed, or some other waveform. The voltage variation is typically from negative to positive, i.e., relative to ground. When in bipolar form, the power output delivered by the two leads is typically about 180° out of phase.

[0060] An "electrode" provides free electrons during plasma generation, for example, when the electrode is connected to a power source that provides a voltage. The electron emitting surfaces of the hollow cathode are collectively considered to be one electrode. The electrodes can be made of materials well known to those skilled in the art, such as steel, stainless steel, copper, or aluminum. However, for each plasma enhanced process, these materials must be carefully selected because different gases will require different electrode materials to initiate and maintain the plasma during operation. By providing the electrodes with a coating, the performance and / or durability of the electrodes can also be improved.

[0061] For any plasma source of the present invention, the power density of the plasma is defined as the power consumed in the plasma generated at the electrode, referenced to the size of the plasma. In a linear hollow cathode type 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.

[0062] "Plasma length in linear meters" refers to the length of the plasma, which is defined as the distance between the ends of the plasma generated by a pair of electrodes in a direction transverse to the direction of travel of the substrate to be coated. When the plasma source includes more than one pair of electrodes, the length of the plasma is defined as the sum of the distances between the ends of the plasma generated by each pair of electrodes in a direction transverse to the direction of travel of the substrate to be coated. It will be well understood by those skilled in the art that these linear hollow cathode plasma sources are scalable in that their length can be adjusted to span the width of the substrate to be treated. The plasma source length can be, for example, several meters. Therefore, it makes sense to express the flow rate and applied power in units based on the total length of the plasma source, because, for example, doubling the length of the plasma source obviously requires doubling the applied power and flow rate.

[0063] As used herein, the following terms have the following meanings: As used herein, "a," "an," and "the" refer to both the singular and the plural, unless the context clearly dictates otherwise. For example, a "cavity" refers to one or more cavities.

[0064] As used herein, "comprise", "comprising", "comprises" and "comprised of" are synonymous with "include", "including", "includes" or "contain", "containing", "contains", and are inclusive or open terms that specify the presence of the following content (e.g., components) but do not exclude or prevent the presence of other unrecorded components, features, elements, components or steps known in the art or disclosed therein.

[0065] The recitation of numerical ranges by endpoints includes all numbers and fragments subsumed within that range, as well as the recited endpoints.

[0066] The paired electrodes forming a chamber in which plasma discharge occurs are each connected to a pipe for introducing a plasma-generating reaction gas, and are provided with openings from which ionized gas (ie, plasma) is discharged.

[0067] The frequency of the power supply connected to the electrodes may be between 5 kHz and 150 kHz, preferably between 5 kHz and 100 kHz.

[0068] The at least one pair of electrodes of the linear plasma source may have a length of 250 mm to 4000 mm and a width of 100 mm to 800 mm.

[0069] Such values ​​have the advantage of ensuring that the amount of reactive gas is sufficiently greater than the amount of precursor so that carbon incorporation into the layer can be controlled and / or avoided.The applied power, reactive gas flow rate and precursor flow rate are adjusted in proportion to the length of the linear plasma source.

[0070] The power provided by the power source is preferably between 5 kW and 50 kW per linear meter of plasma source length, advantageously between 10 kW and 35 kW per linear meter of plasma source length. Below a power of 5 kW per linear meter of plasma source, the presence of carbon in the protective layer is observed, and above 50 kW per linear meter of plasma source, arc formation is observed, which is detrimental to the lifetime of the plasma source and / or the quality of the coating.

[0071] The reaction gas comprises oxygen or an oxygen-containing derivative, which is preferably selected from the group consisting of ozone, hydrogen peroxide, water and CO2. According to an embodiment, the reaction gas may also advantageously comprise an inert gas, such as helium, nitrogen, argon, neon or krypton, to promote the chemical dissociation of the precursor and control the ion bombardment of the source. If present, the percentage of inert gas in the reaction gas is from 2% to 50% by volume, preferably from 3% to 10% by volume, more preferably from 4% to 7% by volume. This choice makes it possible to control the coverage of the obtained layer.

[0072] The reaction gas is preferably O2 or an O2-Ar mixture.

[0073] In an embodiment of the present invention, the flow rate of the reaction gas is 2000 sccm to 5000 sccm per linear meter of the plasma source length.

[0074] A precursor gas containing boron, silicon and hydrogen is injected into the plasma uniformly along the length of the plasma source. The precursor can be injected, for example, between electrodes of an electrode pair, and / or between adjacent electrode pairs if more than one electrode pair is present. The precursor gas is activated by the plasma. A substrate is brought close to the source and a thin layer is deposited on the substrate by the activated gas.

[0075] The flow rate of the precursor gas is preferably between 125 sccm and 750 sccm per linear meter of plasma source length. Typically, if the precursor gas comprises a mixture of precursors, the flow rate of the precursor gas is the sum of the flow rates of the precursors in the mixture.

[0076] The distance between the substrate surface and the opening of the plasma source through which the plasma is emitted from the source is preferably at least 2.0 cm to 20 cm, more preferably at least 4 cm to 15 cm.

[0077] Preferably, the ratio of the flow rate of the reactive gas to the flow rate of the precursor gas is at least 3, advantageously between 3 and 50.

[0078] The precursor gas comprises silicon, boron and hydrogen, and may in particular also comprise carbon and / or oxygen.

[0079] The precursor gas may comprise a single precursor, i.e. a single precursor, or may comprise a mixture of precursors, i.e. a mixture of different precursors of different compositions. The ratio of the precursors is adjusted to set the boron doping at a desired level, in particular a boron content of 4 to 12 atomic % B in the boron-doped silicon oxide layer.

[0080] According to an 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 precursor in the precursor gas may also contain hydrogen. Any precursor in the precursor gas may also contain carbon. Any precursor may also contain oxygen.

[0081] During the deposition of the protective layer, the substrate may reach a temperature between 20° C. and 60° C., depending on the residence time of the substrate in the plasma, for example on the displacement speed of the substrate under the plasma source.

[0082] In an embodiment of the present invention, the silicon-containing precursor is free of boron, ie does not contain boron, and preferably has formula (I), formula (II), formula (III), formula (IV) or formula (V).

[0083] Y1-X-Y2 (I)

[0084] or -[Si(CH3) q (H) 2-q -X-] n - (II)

[0085] or CH2=C(R1)-Si(R2)(R3)-R4 (III)

[0086] or R5-Si(R6)(R7)-R8 (IV)

[0087] or CH2=C(R9)C(O)-O-(CH2) p -Si(R 10 )(R 11 )-R 12 (V)

[0088] Wherein, for formula (I), X is O or NH, Y1 is -Si(Y3)(Y4)Y5, and Y2 is Si(Y 3' )(Y 4' )Y 5' , among which, Y3, Y4, Y5, Y 3' , Y 4' and Y 5' Each is independently H, or an alkyl group of up to 10 carbon atoms; wherein at most one of Y3, Y4 and Y5 is hydrogen, Y 3' , Y 4' and Y 5' at most one of the carbon atoms is hydrogen; and the total number of carbon atoms does not exceed 20.

[0089] wherein formula (II) is cyclic, wherein n is 2 to 10, wherein q is 0 to 2, and wherein the total number of carbon atoms does not exceed 20.

[0090] wherein, for formula (III), R1 is H or an alkyl group, such as -CH3, and wherein R1, R2 and R3 are each independently H, an alkyl group of up to 10 carbon atoms, or an alkoxy group -OZ, wherein Z is preferably -C t H 2t+1 , where t is from 1 to 10.

[0091] wherein, for formula (IV), R5 is H or an alkyl group, such as -CH3, and wherein R6, R7 and R8 are each independently H, an alkyl group of up to 10 carbon atoms, or an alkoxy group -OZ, wherein Z is preferably -C t H 2t+1 , where t is from 1 to 10.

[0092] Wherein, for formula (V), R9 is H or alkyl, such as -CH3, wherein p is 0 to 10, and wherein R 10 , R 11 and R 12 Each is independently H, an alkyl group of up to 10 carbon atoms, or an alkoxy group -OZ, wherein Z is preferably -C t H2t+1 , where t is from 1 to 10.

[0093] The alkyl group may be straight chain or branched, but a straight chain group is preferred. Such an alkyl group is suitably a methyl group or an ethyl group, wherein a methyl group is preferred. 3' , Y 4' or Y 5' All are alkyl.

[0094] The alkoxy group may be straight chain, branched or cyclic, but a straight chain group is preferred. Such an alkoxy group is suitably a methoxy group or an ethoxy group.

[0095] The silicon-containing precursor of formula I may be a precursor containing six methyl groups. Suitably, the silicon-containing precursor of formula I is hexamethyldisiloxane (HMDSO), hexamethyldisilazane or tetramethyldisiloxane (TMDSO).

[0096] The silicon-containing precursor of formula II may be a precursor wherein n is 3, or n is 4, or n is 5, or n is 6. Suitably, the silicon-containing precursor of formula II is octamethylcyclotetrasiloxane. Suitably, the silicon-containing precursor of formula II is hexamethylcyclotrisilazane.

[0097] The silicon-containing precursor of formula V may be wherein p is 2 and wherein R 10 , R 11 and R 12 Each of is a precursor of an alkoxy group (eg, methoxy group). Suitably, the silicon-containing precursor of formula V is 3-(trimethoxysilyl)propyl methacrylate. Suitably, the silicon-containing precursor of formula V is 3-(trimethoxysilyl)propyl acrylate.

[0098] In an embodiment of the present invention, the boron-containing precursor is free of silicon, meaning it contains no Si, and preferably has formula (VI):

[0099] R 13 -B(R 14 )(R 15 )(VI)

[0100] Among them, R 13 , R 14 and R 15 Each is independently H, an alkyl group of up to 10 carbon atoms, or an alkoxy group -OZ, wherein Z is preferably -C t H 2t+1 , where t is from 1 to 10.

[0101] The alkyl group may be straight chain or branched, but a straight chain group is preferred. Such an alkyl group is suitably a methyl group or an ethyl group, among which a methyl group is preferred.

[0102] The alkoxy group may be straight chain, branched or cyclic, but a straight chain group is preferred. Such an alkoxy group is suitably methoxy, ethoxy or isopropoxy.

[0103] In an embodiment of the present invention, for formula (VI), R 13 , R 14 and R 15 All are ethoxy, or R 13 , R 14 , R 15 All are isopropoxy.

[0104] In an embodiment of the present invention, the boron and silicon containing precursor has formula (VII):

[0105] R 16 OB(-OR 17 )(-OR 18 )(VII)

[0106] Among them, R 16 , R 17 and R 18 Each is independently an organosilicon group, in particular a trialkylsilyl group, an alkyl group of up to 10 carbon atoms. Suitably, the trialkyl group is a trimethylsilyl group, a triethylsilyl group, or a diethyl(methyl)silyl group. Suitably, the boron and silicon precursor is tris(trimethylsilyl)borate (TTMSB).

[0107] Preferably, any precursor of boron, silicon, and / or both silicon and boron is delivered to the plasma source without the use of a carrier gas. However, in some embodiments, an additional gas may be used as a carrier gas to introduce the precursor into the plasma chamber.

[0108] Preferably, any precursor is supplied as a liquid which is subsequently vaporized and delivered to the plasma source in its vaporized form. Preferably, any vaporized precursor is delivered to the plasma chamber without the use of a carrier gas. Alternatively, if desired, a liquid precursor supply system delivers the vaporized precursor to the plasma chamber using a carrier gas.

[0109] 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 a preferred process, a single carrier gas is used. This is most preferably He or Ar.

[0110] Preferably, when a carrier gas is used, the amount of carrier gas is from about 5% to about 1500% carrier gas, preferably from about 10% to about 1000% additional gas, more preferably from 20% to 750%, such as 25% to 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 based on the total flow of all silicon and boron precursors.

[0111] Any of the precursors may be gaseous at room temperature and pressure, or may be a vaporized liquid.

[0112] In order to obtain a high dynamic deposition rate of about 20 nm.m / min to 500 nm.m / min, the following flow rates of different precursors are necessary. Generally, higher precursor flow rates require higher power to be applied to the plasma source.

[0113] In an embodiment of the present invention, the total flow rate of the silicon-containing precursor is 10 sccm to 500 sccm (standard cubic centimeters per minute) per linear meter of plasma length, preferably 50 sccm to 500 sccm, or 50 sccm to 400 sccm per linear meter of plasma length.

[0114] The unit "nm.m / min" is used in this application to express deposition rate. This unit is a combination of SI units and is commonly used to characterize the deposition rate of a dynamic or continuous coating process (i.e., a process in which the substrate moves continuously through a deposition device). The deposition rate of such a deposition device is often referred to as the "dynamic deposition rate" (DDR), which is used to express the deposition rate of the coating device itself, regardless of the speed at which the substrate moves through the deposition device.

[0115] In an embodiment of the present invention, the total flow rate of the boron-containing precursor is 10 sccm (standard cubic centimeters per minute) to 500 sccm per linear meter of plasma length, preferably 50 sccm to 500 sccm, or 50 sccm to 400 sccm per linear meter of plasma length.

[0116] In an embodiment of the present invention, the total flow rate of the silicon and boron containing precursors is 10 sccm (standard cubic centimeters per minute) to 750 sccm per linear meter of plasma length, preferably 50 sccm to 750 sccm, or 50 sccm to 600 sccm per linear meter of plasma length.

[0117] Optionally, step c) may additionally comprise applying additional precursors to the substrate, for example in order to include specific additional oxides, such as titanium oxide or zirconium oxide, to further improve the mechanical and / or chemical durability and / or increase the refractive index of the boron-doped silicon oxide protective layer.

[0118] According to an embodiment of the present invention, the boron-doped silicon oxide protective layer contains at least 80 wt % of silicon oxide SiO 2 .

[0119] According to an embodiment of the present invention, the boron-doped silicon oxide protective layer contains up to 15 wt % of titanium oxide, zirconium oxide or a mixture thereof.

[0120] The invention is defined in the appended independent claim. Preferred embodiments are defined in the dependent claims.

[0121] It should be noted that the present invention relates to all possible combinations of features recited in the claims or in the above-described embodiments.

[0122] Example

[0123] A boron-doped silicon oxide protective layer is deposited as the topmost layer on various glass substrates to form a multi-layer coated glass substrate.

[0124] Substrate A is a 4 mm thick ordinary transparent soda lime glass substrate with the following sequence of layers (Table 1), numbered from the glass surface before the addition of the protective layer of boron doped silicon oxide. The layers were deposited using magnetron sputtering.

[0125] Table 1 - Substrate A layer sequence

[0126] Layer number Layer Material Layer thickness range (nm) 1 <![CDATA[Zn2SnO4]]> 25-35 2 ZnO:Al 3-8 3 Ag 10-11 4 ZnO:Al 2-10 5 <![CDATA[Zn2SnO4]]> 25-30 6 <![CDATA[Si3N4]]> 25-40 7 <![CDATA[Zn2SnO4]]> 8-15 8 <![CDATA[Ti x Zr y Oh z ]]> 2-5 9 ZnO:Al 3-8 10 Ag 13-15 11 ZnO:Al 2-10 12 <![CDATA[Zn2SnO4]]> 5-10 13 <![CDATA[Si3N4]]> 20-23 14 <![CDATA[Ti x Zr y Oh z ]]> 1-3

[0127] ZnO:Al is an aluminum-doped zinc oxide layer containing 2 wt % to 10 wt % aluminum.

[0128] Ti x Zr y O z Denotes a mixed oxide of titanium and zirconium comprising 65% by weight of titanium oxide and 35% by weight of zirconium oxide.

[0129] The precursors used to deposit the protective layer are given in Table 2 below. In the vacuum chamber, the glass substrate is transported at a continuous speed on a roller conveyor under the PECVD source in a direction transverse to the length of the PECVD source. The glass substrate can pass under the PECVD source multiple times to achieve the desired layer thickness (number of passes).

[0130] The PECVD source used consisted of two pairs of electrodes, each 40 cm long, placed perpendicular to the direction of movement of the substrate. This resulted in a total plasma length of 80 cm. A power of 16 kW was applied to the plasma source, with the power applied being 16 kW / 0.8 m = 20 kW per linear meter of plasma source length. The flow rate of the O2 reaction gas was adjusted to reduce any carbon content in the coating to undetectable levels. The deposition parameters are given in Table 3 below.

[0131] Table 2

[0132]

[0133] Prior to 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 power applied was 12.5 kW / m. Example 0 is a comparative substrate A on which no protective layer was deposited. Examples 1, 2, 9 and 10 are comparative samples coated with a silicon oxide layer without boron doping. Examples 3 to 6 and 11 illustrate the deposition possibilities using a precursor mixture. Examples 7 and 8 were performed using a single precursor.

[0134] Table 3

[0135]

[0136]

[0137] The dynamic deposition rate (DDR), refractive index, boron content and thickness obtained for different examples are shown in Table 4. This deposition rate is significantly higher than that obtainable by magnetron sputtering.

[0138] Table 4

[0139]

[0140] X-ray fluorescence spectroscopy was used to determine the atomic percentage of B in the boron-doped silicon oxide layer. To determine the carbon content, the same coating was deposited on a silicon substrate and the FTIR spectroscopy (Fourier Transform Infrared Spectroscopy) spectrum was measured. No carbon bonds were detected.

[0141] Neutral Salt Spray Test (NSST) - This test consists in subjecting the specimens to a salt spray formed by spraying an aqueous solution containing 50 g / l of sodium chloride in a chamber maintained at 35°C (full details of this test are detailed in the international standard ISO 9227-1990), with an exposure time of at least 5 days, or at least 10 days, or at least 21 days.

[0142] Cleveland Test (Clev) - This test is run according to standard ISO 6270-1:1998 and lasts for at least 2.0 days, or 5 days, or 10 days, or 15 days.

[0143] Climate Chamber Test (CC) - This test consists in placing the sample in a chamber filled with a H2O atmosphere and subjecting it to a temperature cycle every 2 hours during which the temperature varies from 45°C to 55°C and back to 45°C for at least 2.0 days, or 5 days, or 10 days, or 21 days. CC BB is a test carried out on the glazing before heat treatment (before baking), while CC AB is a test carried out on the glazing after heat treatment (after baking).

[0144] The results of each of the above tests are obtained by visually evaluating the samples in comparison with the defined reference sample grades. The grades for the Cleveland test, the climate chamber test and the salt spray test are based on an internal grade from 0 to 5, where 0 corresponds to a standard sample with severe deterioration (such as pixels, deep spots, stretch marks, etc.). The value 5 corresponds to a perfect or essentially perfect surface without any signs of deterioration. Intermediate values ​​(down to 0.25 units) correspond to samples with internal grades of different degrees of deterioration, ranked in order of degree of deterioration. Acceptable values ​​range from 3 to 5.

[0145] Table 5 below shows the results of the different tests. Some samples were tested before and after a thermal treatment. The thermal treatment consisted in placing the samples inside a convection oven at a temperature of 670° C. for 4 to 5 minutes.

[0146] Table 5

[0147]

[0148] While some improvement prior to heat treatment was observed for Examples 1 and 2, which comprised silicon oxide without boron doping, significantly reduced performance was observed compared to Examples 3-7, which had boron doped silicon oxide coatings.

[0149] Substrate B is a 4 mm thick ordinary transparent soda lime glass substrate provided by magnetron sputtering with the following order of layers (Table 5), numbered starting from the glass surface. Then different boron doped silicon oxide protective layers were added by PECVD according to the conditions of Table 6. Then, a 20 nm thick zirconium doped silicon oxide layer was added by magnetron sputtering. These layers were deposited using magnetron sputtering. The resulting multilayer coating is an antireflective coating. Example 16 and Example 17 are comparative examples without boron doping.

[0150] Table 5 - Layer sequence of substrate B

[0151] Layer number Layer Material Layer thickness range (nm) 1 <![CDATA[Ti x Zr y Oh z ]]> 12 2 <![CDATA[SiO2:Al]]> 34 3 <![CDATA[Ti x Zr y Oh z ]]> 126

[0152] Table 6

[0153]

[0154] Table 7

[0155]

[0156] Table 8

[0157]

[0158] Examples 16 to 19 all have almost the same optical properties. Examples 16 and 17 do not include a boron-doped silicon oxide protective layer and show little resistance to heat treatment or alkaline solution, respectively, while Examples 18 and 19 include a boron-doped silicon oxide protective layer and show good resistance to both heat treatment and alkaline solution.

Claims

1. A glass substrate with a multilayer coating, the multilayer coating comprising a protective layer of boron-doped silicon oxide, wherein: The boron-doped silicon oxide comprises: a. Si, O, B, wherein the boron content is between 4 atomic % and 12 atomic %, and b. OH group.

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

3. The glass substrate according to any one of the preceding claims, wherein: The protective layer has an FTIR absorption peak area ratio A of -OH stretching vibration absorption peak area to Si-O-Si stretching vibration absorption peak area between 0.25 and 0.

5. OH / A SiOSi .

4. The glass substrate according to any one of the preceding claims, wherein: The thickness of the protective layer is at least 50 nm and at most 400 nm.

5. The glass substrate according to any one of the preceding claims, wherein The refractive index of the protective layer at a wavelength of 633 nm is between 1.4 and 1.

5.

6. The glass substrate according to any one of the preceding claims, wherein: The protective layer contains at least 80% by weight of SiO2.

7. The glass substrate according to any one of the preceding claims, wherein: The protective layer contains up to 15 wt % of titanium oxide, zirconium oxide, or a mixture of titanium oxide and zirconium oxide.

8. The glass substrate according to any one of claims 1 to 6, wherein The protective layer consists essentially of Si, B, O and H.

9. The glass substrate according to any one of the preceding claims, wherein: The multi-layer coating is selected from the group consisting of an anti-reflective coating, a UV reflective coating, an insulating low-emissivity coating, and a solar control coating.

10. A method for depositing a boron-doped silicon oxide protective layer on a glass substrate, the protective layer comprising Si, O, and OH groups, wherein: The boron content is between 4 atomic % and 12 atomic %, and the method comprises: a. Providing a glass substrate, b. providing a linear hollow cathode type plasma source, the length of the plasma source comprising at least one pair of hollow cathode plasma generating electrodes, and the plasma source comprising at least one electrode pair connected to an AC, DC or pulsed DC generator power supply for depositing the protective layer on the substrate, c. injecting a plasma containing oxygen into the electrode of the plasma source to generate a reactive gas at a flow rate of 125 sccm to 750 sccm per meter of plasma source length, d. applying an electric power of 10 kW to 50 kW per meter of plasma source length to the plasma source, and e. injecting a precursor gas at a flow rate of 500 sccm to 2500 sccm per linear meter of plasma source length, wherein the precursor gas is injected into the plasma at least between the electrodes of each electrode pair of the plasma source, and depositing the protective layer on the glass substrate by exposing the substrate to the plasma of the plasma source.

11. The method 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.

12. The method according to claim 10 or 11, wherein: The reaction gas is O2 or an O2-Ar mixture.

13. The method according to any one of claims 10 to 12, wherein: The flow rate of the reaction gas is 2000 sccm to 5000 sccm per linear meter of the plasma source length.

14. The method 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 wherein a total flow rate of each precursor is between 10 sccm and 500 sccm.

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