Silicon oxide coated polymer film and low pressure PECVD method for producing same

Abstract

The present invention relates to a stress-free, transparent silicon oxide-coated polymer substrate. The present invention further relates to a method for depositing a stress-free, transparent silicon oxide-based layer on a polymer substrate using a PECVD apparatus including at least one hollow cathode plasma source.

Description

[Technical Field]

[0001] This invention relates to a stress-free transparent silicon oxide coated polymer substrate. The invention further relates to a method for depositing a stress-free transparent silicon oxide-based layer onto a polymer substrate, specifically onto a thin polymer film, and more specifically onto a thin polyethylene terephthalate (PET)-based polymer film, and for promoting adhesion of the laminated material to the polymer substrate. In particular, this method is suitable for use in continuous coating methods. [Background technology]

[0002] Silicon oxide-based layers can be used on polymer substrates for a variety of purposes. They can be used as barrier layers against water vapor or gases. They can also be part of more complex stacks of multiple layers used to modify the optical or optical energy properties of polymer films, such as anti-reflective layer stacks, low-emissivity insulating layer stacks, or solar radiation regulating layer stacks. They can also be used to improve the adhesion of polymer substrates to other substrates or adhesives or other coating layers.

[0003] To fabricate silicon oxide-based layers, the so-called PECVD method (plasma-accelerated chemical vapor deposition) can be used. These methods can be used to coat many different substrates for various layer materials. Common problems encountered with polymer substrates are the rise in substrate temperature and etching of the polymer substrate surface by plasma reaction species. For example, it is known that SiO2 and Si3N4 layers with a thickness of 20-30 nm can be deposited on a 13 μm PET substrate using microwave excitation and / or high-frequency PECVD. Interesting barrier properties can be obtained, while 10 nm·m·min -1 A dynamic deposition rate of less than 1 is very low for a 200 nm thick coating [ASda Silva Sobrinho et al., J.Vac.Sci.Technol.A 16(6), November / December 1998, p.3190-3198].

[0004] When silicon oxide for a transparent barrier layer is deposited on a PET substrate by PECVD, oxygen barrier properties and water vapor barrier properties can be obtained [RJ Nelson and H. Chatham, Society of Vacuum Coaters, 34th Annual Technical Conference Proceedings (1991) pp. 113-117 and M. Izu, B. Dotter, SROvshinsky, Society of Vacuum Coaters, 36th Annual Technical Conference Proceedings (1993) pp. 333-340].

[0005] Disadvantages of known PECVD methods include, in particular, that the deposition rate is too low for use in methods where the substrate moves rapidly through one or more deposition processes, such as high-speed roll-to-roll methods. Furthermore, in known PECVD methods, higher deposition rates tend to result in higher substrate temperatures, which consequently limits the maximum deposition rate and / or necessitates additional cooling for the polymer substrate. In addition, the adhesion of these coatings to the polymer substrate tends to be weak, and / or the inherent compressive stress in the coating is often high, causing deformation of the coated PET substrate.

[0006] Furthermore, it is known that silicon oxide-based layers can be applied by sputtering. The drawback of sputtered layers is the high cost resulting from the low productivity of the silicon oxide sputtering method, i.e., the low dynamic deposition rate. More importantly for thin polymer films, except at minimum thickness, the inherent compressive stress of the sputtered silicon oxide-based coating causes deformation of the polymer substrate of the coated thin film. [Overview of the Initiative]

[0007] One of the objectives of the present invention is to obtain a silicon oxide-based layer on a polymer substrate, specifically on a polymer film, using a low-pressure PECVD method (in this application, the pressure may be 0.005 to 0.025 Torr) that enables one or more of the following: a high deposition rate, a very transparent silicon oxide-based film, and minimizing deformation of the coated thin polymer substrate, and minimizing the amount of stress in the coating in order to minimize the risk of delamination.

[0008] The present invention relates to a method for producing a silicon dioxide-based layer on a polymer substrate, specifically on a thin polymer film, using the PECVD method. a. The step of providing a polymer substrate, b. Providing a low-pressure PECVD apparatus for depositing a film onto a polymer substrate, comprising at least one linear hollow cathode plasma source, wherein each plasma source comprises at least one pair of electrodes connected to an AC, DC, or pulsed DC generator. c. The step of applying power to the plasma source such that the plasma power density is 1kW to 50kW per linear meter of the plasma source, d. A step of applying a gaseous precursor of silicon oxide to a polymer substrate at a flow rate of 50 to 700 sccm per linear meter of the plasma source, wherein the gaseous precursor is injected between the electrodes of each electrode pair, between two pairs consisting of each electrode constituting each electrode and the reactive gas injected into each electrode, at a flow rate of 1500 to 4000 sccm per linear meter of the plasma source, and the reactive gas is based on oxygen or an oxygen-containing derivative. This also relates to methods that include this.

[0009] The present invention further relates to silicon dioxide-based layers that can be made by the method of the present invention, any embodiment of the method, or any combination of multiple embodiments of the method.

[0010] The present invention further relates to a polymer substrate coated with a silicon dioxide-based layer of the present invention, a coated polymer substrate that can be made by the method of the present invention or any embodiment of the method.

[0011] High dynamic deposition rates can be achieved by the method of the present invention. Specifically, by using this method, a silicon oxide-based layer firmly adhered to a polymer substrate can be obtained at a high dynamic deposition rate. Furthermore, the substrate thus coated may exhibit a limited amount of deformation. The inventors have found that this is possible by combining, as necessary, the requirements of employing a linear hollow cathode PECVD apparatus, employing a specific power density of the plasma, and preferably having a ratio of the flow rate of the reactive gas to the flow rate of the gaseous precursor that is at least the ratio necessary to obtain the layer. When the layer is deposited on the polymer substrate, its optical properties, specifically transmittance, can also be optimized. The silicon oxide-based layer deposited by the method of the present invention exhibits low stress, and the substrate experiences a low thermal load during the coating process. For these reasons, the resulting coated substrate is expected to exhibit low deformation and high coating adhesion.

[0012] The PECVD method of the present invention exhibits one or more of the processing advantages listed above: a high dynamic deposition rate of at least 200 nm × m / min, ease of processing on an industrial scale, excellent uniformity of the resulting layer (thickness variation < 5%), low heat transfer to the polymer substrate, especially without substrate cooling, minimal deformation of the polymer substrate, specifically thin polymer film substrates, and low installation costs.

[0013] The above-described and further embodiments of the present invention will be explained in more detail by reference to the accompanying drawings. [Brief explanation of the drawing]

[0014] [Figure 1] A schematic cross-sectional view of a low-pressure PECVD apparatus is shown, including a linear hollow cathode plasma source with a pair of electrodes that coat a polymer substrate with silicon oxide.

[0015] [Figure 2] This shows a cross-sectional view of a roll-to-roll coating apparatus for carrying out the method of the present invention. [Modes for carrying out the invention]

[0016] These figures are not drawn to a consistent scale.

[0017] The method preferably requires a low-pressure PECVD apparatus operating in a housing at a pressure of 0.005 to 0.025 Torr, preferably 0.010 to 0.020 Torr, and more preferably 0.013 to 0.015 Torr, the apparatus comprising a linear hollow cathode plasma source connected to an AC or pulsed DC generator (the frequency of which is advantageously 5 to 150 kHz, preferably 5 to 100 kHz) or a DC generator.

[0018] An example of a PECVD apparatus is described below. The PECVD apparatus may be provided in a vacuum chamber. This vacuum chamber is preferably arranged to have different apparatuses adjacent to each other that provide different deposition modes or surface treatments. These apparatuses that enable different deposition modes may be flat or rotating cathodes for magnetron sputtering deposition. This vacuum chamber may be combined in particular with means for transporting substrates. Specifically, this vacuum chamber may be combined with means for transporting thin polymer films along each deposition apparatus in a roll-to-roll manner.

[0019] The PECVD apparatus of the present invention may consist of, for example, a hollow cathode plasma source including at least one pair of electrodes connected to an AC or pulsed DC generator from which a discharge occurs, and an opening in the electrode from which plasma is emitted. In a preferred embodiment, the hollow cathode plasma source includes at least two pairs, at least three pairs, or at least four pairs of electrodes. Each electrode or cavity is connected to a pipe from which a gas or gas mixture that is ionized when a discharge occurs can be introduced into the cavity.

[0020] The "PECVD apparatus including a linear hollow cathode plasma source" is construed to mean a linear plasma enhanced chemical vapor deposition source including one or more pairs of electrodes configured to generate hollow cathode discharge. An example of a hollow cathode plasma source is described in U.S. Patent No. 8,652,586 to Maschwitz, which is hereby incorporated by reference in its entirety. FIG. 1 shows a hollow cathode type plasma source that can be used in the present invention. The plasma source includes at least one pair of linear hollow cathode electrodes (1a) and (1b) arranged in parallel and connected via an AC power source (not shown). An electrical insulating material (9) is disposed around the hollow cathode electrodes. Plasma generating gas is supplied through inlets (5a) and (5b). The precursor gas is supplied through the precursor gas inlet (6) and is introduced into the plasma curtain (3) through the manifold (7) and the precursor injection slots (8) in the dark area between the electrodes. The AC power source supplies a variable or alternating bipolar voltage to the two electrodes. The AC power source first enables the formation of plasma by driving the first electrode to a negative voltage, while the second electrode is driven to a positive voltage to function as an anode for the voltage application circuit. Next, this power source drives the first electrode to a positive voltage and reverses the roles of the cathode and the anode. Since one of the electrodes is driven negatively (1a), a discharge (2a) occurs in the corresponding cavity. Next, when the other electrode forms an anode, electrons escape from the plasma through the outlet (10) and move to the anode side, thereby completing the electrical circuit. In this way, a plasma having a curtain shape (3) is formed along the length of the electrodes in the region between the first electrode and the second electrode above the substrate (4). The substrate (4) is depicted here as a single polymer sheet, but it can be in the form of a long ribbon, for example, in a roll-to-roll type coating apparatus. This method of driving the hollow cathode using AC power contributes to the formation of a uniform linear plasma extending across the entire polymer substrate, which is perpendicular to the direction of movement (11) of the polymer substrate. In this patent, the electron emission surface of the electrode may also be referred to as the plasma generation surface.

[0021] "Closed-loop electron drift" is interpreted to mean an electron flow generated by crossed electric and magnetic fields. In many conventional plasma-forming devices, the closed-loop electron drift forms a closed circulation path or "race track" of the electron flow. The hollow cathode PECVD device of the present invention operates without a closed-loop electron drift.

[0022] "AC power" is interpreted to mean power from an alternating current power source where the voltage varies at a certain frequency in a sine wave, square wave, pulse waveform or other waveform format. The voltage change often occurs from negative to positive with respect to ground. In bipolar form, the power output fed by two conductors is generally out of phase by about 180°.

[0023] "Electrodes" provide free electrons during plasma generation, for example while they are connected to a power source that provides voltage. The two electron emission surfaces of the hollow cathode are considered together as one pair of electrodes. Electrodes can be made from materials well-known to those skilled in the art, such as steel, stainless steel, copper or aluminum. However, in the case of plasma-enhanced chemical vapor deposition (PECVD), these materials should be carefully selected because different gases may require different electrode materials to initiate and maintain the plasma during operation. It is also possible to improve the performance and / or durability of the electrodes by applying a coating to them.

[0024] The PECVD device may be particularly suitable for use in a continuous coating process where the substrate moves continuously under the PECVD device rather than being fixed under the PECVD device. Specifically, the substrate may move in a direction perpendicular to the length of the plasma source.

[0025] The power density of the plasma is defined as the power dissipated in the plasma generated by one or more electrodes, in light of the size of the plasma.

[0026] The "plasma linear meter," also referred to herein as the "total plasma length," is defined as the distance between the edges of the plasma generated by a pair of electrodes in a direction transverse to the direction of movement of the polymer substrate being coated. If the plasma source includes two or more pairs of electrodes, the total plasma length is defined as the sum of the distances between the edges of the plasma generated by each pair of electrodes in a direction transverse to the direction of movement of the polymer substrate being coated.

[0027] In a linear hollow cathode plasma source, the "plasma power density" can be defined as the total power applied to the source divided by the total length of the plasma.

[0028] According to the present invention, a reactive gas based on oxygen O2 or an oxygen-containing derivative may be used, the latter preferably selected from the group consisting of ozone, hydrogen peroxide, water, and CO2. In some embodiments, the reactive gas may further contain an inert gas such as helium, nitrogen, argon, neon, or krypton to advantageously promote the chemical dissociation of the precursor and to control the ion bombardment by the source. In advantageous embodiments, the reactive gas is selected from O2 or an O2-inert gas mixture (e.g., an O2-Ar mixture). Such an ionizable reactive gas or gas mixture is introduced into the electrode cavity of the plasma source at a specific flow rate and can be controlled by a mass flow meter that may be placed in the pipe between the gas reservoir and the plasma source. When an O2-inert gas mixture is used, the ratio of O2 to the inert gas (e.g., O2 to Ar) is defined by the ratio of the flow rate of O2 to the flow rate of the inert gas, and is in the range of 2 to 50, preferably 10 to 30, and very advantageously 15 to 25.

[0029] The silicon oxide precursor gas is preferably injected uniformly along the length of the plasma source between at least two electrodes of the electrode pair of the plasma source. This precursor gas is activated when it enters contact with the plasma. The substrate is brought close to the plasma source and thus exposed to the activated precursor, and a thin layer based on silicon oxide is deposited on the substrate from the activated precursor gas. The precursor gas may be a gas under standard temperature and pressure conditions, i.e., around room temperature and atmospheric pressure. The precursor gas may be a solid or preferably a liquid under standard temperature and pressure conditions, and may also be an already vaporized precursor.

[0030] The amount, or flow rate, of the reactive gas or gas mixture and precursor gas injected into the plasma is controlled, for example, by a liquid or vapor mass flow meter.

[0031] The operating pressure range of the plasma source is preferably 0.005 to 0.025 Torr. The PECVD apparatus for the method of the present invention is preferably provided in a vacuum chamber maintained at a pressure of 0.005 to 0.025 Torr, which can be maintained by vacuum pumping means while injecting various reactants and precursor gases. Vacuum pumping is preferably provided by a turbomolecular pump connected to a vacuum chamber surrounding the plasma source, configured to provide a uniform gas flow rate upstream and downstream of the PECVD apparatus. Preferably, pumping is provided at least on the side of the coated substrate. Optionally, pumping is also provided on the side of the substrate opposite to the coated side.

[0032] In certain embodiments of the present invention, the ratio of the reactive gas to the precursor gas is sufficient to convert at least all of the C, H, and Si in the precursor molecules into CO2, H2O, and SiO2. Specifically, the ratio of oxygen atoms of the reactive gas to the precursor molecules is at least 2 O atoms per precursor molecule, and preferably 5 to 30 O atoms per precursor molecule.

[0033] Furthermore, in an advantageous embodiment of the present invention, the amount of oxygen or oxygen-containing derivative is sufficient to convert at least all of the carbon, hydrogen, and / or silicon in the precursor into CO2, H2O, and SiO2. That is, the carbon, hydrogen, and silicon-containing portion of the precursor is C x H y Si z When expressed as , the amount of oxygen atoms q provided is preferably at least q = 2x + 0.5y + 2z. In fact, it has been found that lower oxygen levels result in increased absorption in silicon dioxide-based films.

[0034] More specifically, the ratio of the power per linear meter (i.e., power density) of the plasma source to the pressure in the vacuum chamber is favorably 1.5 (kW / m) / mTorr or less, more favorably 0.9 (kW / m) / mTorr or less, and more favorably 0.8 (kW / m) / mTorr or less. By limiting this power-to-pressure ratio, it was found that the temperature rise of the substrate during the coating process remained very gentle. Specifically, the substrate temperature could be maintained at 60°C or less, favorably 50°C or less, and more favorably 45°C or less, especially in the absence of additional substrate cooling means.

[0035] In other words, in certain embodiments of the present invention, by controlling the ratio of power density to pressure as described above, the rise in substrate temperature by the method of the present invention in the absence of additional substrate cooling means is less than 40°C, preferably less than 30°C, and more preferably less than 25°C. The substrate temperature can be measured using a thermocouple or estimated using an irreversible temperature monitoring label.

[0036] In certain embodiments of the present invention, the temperature reached by the PECVD method is at least 20°C, alternatively at least 25°C, or alternatively at least 30°C. This temperature reached by the substrate is maintained throughout the coating process when there is no means of cooling the substrate.

[0037] In certain embodiments of the present invention, the ratio of the power per linear meter of the plasma source to the pressure in the vacuum chamber is, advantageously, at least 0.2 (kW / m) / mTorr, more advantageously, at least 0.4 (kW / m) / mTorr, and more advantageously, at least 0.6 (kW / m) / mTorr. Under these conditions, it has been found that substrate etching damage is very little or even completely absent.

[0038] Further coating or surface treatment methods may, of course, require substrate cooling means either away from or near the PECVD apparatus.

[0039] Preferably, in any embodiment of the present invention, the source of the PECVD apparatus may have dimensions of 250 mm to 4000 mm in length and 300 to 600 mm in width per pair of electrodes.

[0040] In any embodiment of the present invention, the power density is applied between two electrodes such that the power density can be 1 to 50 kW per linear meter of plasma, preferably 2 to 30 kW per linear meter of plasma, and more preferably 3 to 15 kW per linear meter of plasma. Above 50 kW per meter of plasma, the formation of powder in the gas phase, which is detrimental to the quality of the deposition, may be observed.

[0041] The silicon dioxide precursors that may be used in any embodiment of the present invention depend on the properties of the layer to be deposited. Specifically, these are gaseous or volatile products at the temperature and pressure under which the method is carried out. Common silicon dioxide precursors include SiH4 (silane), TMDSO (tetramethyldisiloxane), and HMDSO (hexamethyldisiloxane), but this list is not exhaustive.

[0042] The flow rate of the gaseous precursor is 50 to 700 sccm (standard cubic centimeters per minute) per linear meter of the plasma source, preferably 150 to 500 sccm or 200 to 500 sccm per linear meter of the plasma source. This range is necessary to obtain a high deposition rate suitable for this technique, preferably on the order of 200 to 400 nm × m / min.

[0043] The present invention further relates to silicon oxide-based layers deposited using any embodiment or any combination of any of the embodiments of the method of the present invention.

[0044] The present invention also relates to polymers at least partially coated with the silicon dioxide-based layer of the present invention.

[0045] The silicon dioxide-based layer of the present invention may have a geometric thickness of 2 to 1500 nm, preferably 20 to 800 nm, and particularly 30 to 600 nm. The selected thickness is determined by the technical effects required for the substrate thus coated.

[0046] In certain embodiments of the present invention, the silicon dioxide-based layer is in direct contact with the polymer substrate. In certain other embodiments of the present invention, another layer is present between the polymer substrate and the silicon dioxide-based layer.

[0047] Preferably, the silicon dioxide-based layer of the present invention is SiO 2-x The silicon dioxide-based layer includes H, C, N, Cl, CH z derivative, NH y Derivatives and OH yThe product may contain up to 10 atomic percent of precursor residues from the group consisting of derivatives (where y is 1 to 4). This content is preferably determined by photoelectron spectroscopy (XPS) or secondary ion mass spectrometry (SIMS), and can also be determined by ion beam analysis techniques such as Raman spectroscopy, NRA, and RBS.

[0048] The silicon dioxide-based layer of the present invention is amorphous and homogeneous throughout its entire thickness, as can be determined by cross-sectional transmission electron microscopy (TEM). Specifically, there is no detectable transition in the silicon dioxide-based layer from a composition containing more organic residue to a composition containing no organic residue at all.

[0049] The polymer substrates of the present invention may be homogeneous polymer sheets, but other shapes are also possible. They do not have to contain fibers. Alternatively, they may contain glass fibers in another homogeneous polymer matrix. Specifically, they do not have to be fiber-based fabrics or cloths. The silicon oxide-based layer may be present on at least a portion of the polymer, for example, on one surface of the polymer sheet or on the entire polymer substrate.

[0050] The polymer substrates of the present invention may include acrylic polymers, polymethyl methacrylate (PMMA) and its copolymers, CR-39 or allyl diglycol carbonate (ADC), polycarbonate, polypropylene (PP), biaxially oriented polypropylene (BOPP), polyethylene (PE), polyvinyl chloride (PVC), polyethylene terephthalate (PET), polystyrene, cyclic olefin copolymers (COCs), and polyethylene terephthalate glycol (PETG), as well as combinations thereof. The polymer substrates of the present invention may include thermoplastic elastomers (TPEs), sometimes called thermoplastic rubbers, which are a class of copolymers or a physical mixture of polymers (usually plastics and rubbers) made of materials having both thermoplastic and rubber-like elasticity. Specifically, the polymer substrate may include styrene block copolymer (TPS (TPE-s)), thermoplastic polyolefin elastomer (TPO (TPE-o)), thermoplastic vulcanized product (TPV (TPE-v or TPV)), thermoplastic polyurethane (TPU (TPU)), thermoplastic copolyester (TPC (TPE-E)), and thermoplastic polyamide (TPA (TPE-A)).

[0051] The polymer substrate may be a thin polymer film having a thickness ranging from 5 μm to 300 μm, alternatively 10 to 250 μm, alternatively 20 to 200 μm, or alternatively 25 to 150 μm. These thin polymer films can be processed in a roll-to-roll manner, for example, as shown in Figure 2. In Figure 2, the polymer film substrate (29) is unwound from an unwinding roll (21) and, on a roll (27), is reoriented toward the main roll (25) where the coating method of the present invention will occur. The polymer film is then directed on a roll (28) to be wound onto a winding roll (22). The coating method of the present invention is carried out using a PECVD apparatus (23) that generates plasma (26) on the surface of the polymer substrate where a silicon oxide precursor is activated to form a silicon oxide coating on the polymer film substrate. The arrows in Figure 2 indicate the direction of movement of the thin polymer film. The direction of the film can be reversed to move the polymer film substrate in the opposite direction to repeat the coating method. Further surface treatment or coating apparatus (24) may be located near the PECVD apparatus of the present invention. These thin polymer films may specifically include PET and PMMA.

[0052] The applicability of this method depends on the properties of the layers deposited on the substrate. Various embodiments of the present invention for different applications are described below.

[0053] The substrate is, very advantageously, a conventional polymer substrate or polymer film, such as a polymer film derived from polyethylene. In connection with the present invention, the substrate may be a substrate that is already pre-coated with another layer which also has barrier layer properties.

[0054] In FIG. 1, the PECVD apparatus shown is a linear dual-beam plasma source (10) that includes two cavities (13) where discharges occur and an opening (14) through which it is emitted. Each cavity includes an electrode (12) connected to a generator (11) that generates alternating current (AC) or pulsed DC. The plasma source includes a series of magnets (15) that face each other and are arranged along the cavity. Thus, the gas injected into each cavity is ionized to form an ion beam. It forms what is known as a source of plasma (16) that is emitted out of the plasma source in the direction of the substrate (30) to be coated through the opening (14). The arrow indicates the forward direction of travel of the substrate during deposition. The full width of the plasma is represented by "w", and the full length of the plasma relates to that portion measured perpendicular to, i.e., in a direction transverse to, the direction of travel of the substrate.

[0055] It should be noted that the present invention relates to all possible combinations of the features described in the claims.

[0056] In the present invention, value ranges indicated as being between boundary values are intended to include those boundary values.

Example

[0057] As shown below, silicon oxide-based coatings were deposited on PET sheets of different thicknesses using different precursors. The size of the sheets was approximately 210 mm × 297 mm. The PECVD apparatus used a hollow cathode plasma source that included two pairs of electrodes each having a length of 40 cm. Thus, the full length of the generated plasma was 2 × 40 = 80 cm.

[0058] The indicated flow rates in sccm were calculated for a temperature of 273.15 K (0 °C, 32 °F) and an absolute pressure of 10 5 Pa (100 kPa, 1 bar).

[0059] The temperature was checked using a THERMAX (registered trademark) irreversible temperature monitoring label that has sensitivity in the temperature range of 37 - 65 °C.

[0060] The precursor used was SiH4 for Examples 1-15 and TMDSO for Examples 16-31. The substrate was attached to a 4mm glass sheet and transported at a continuous speed in a direction transverse to the length of the PECVD source on a roller conveyor below the source. The reactant for Examples 1-31 was O2. Other deposition parameters are shown in Table 1 below.

[0061] TIFF2023507602000002.tif234170

[0062] Table 2 below shows the power / pressure ratio, substrate temperature, coating thickness, and transmittance measured at a 2° instrument angle using Illuminant D65. Coating thickness was measured at the edges of the masked substrate region during coating deposition using a Dektak® stylus profiler.

[0063] TIFF2023507602000003.tif235170

[0064] The silicon oxide layers deposited in Examples 1-15 had a carbon content below the detection limit of X-ray photoelectron spectroscopy when deposited on glass samples for comparison. The silicon oxide layers in Examples 16-31 had a carbon content of 3-10 atomic percent. For samples deposited using a power density / pressure ratio greater than 0.5 (kW / m) / mTorr, the carbon content was 3-8 atomic percent.

[0065] The deformation of the thin PET substrate due to stress in the silicon oxide layer was very small. In all coated examples, the coated sheet remained perfectly flat when observed with the naked eye while placed on a flat glass sheet.

Claims

1. A method for producing a silicon oxide based layer on a polymer substrate, the method comprising the steps of: a. providing a polymer substrate; b. providing a low pressure PECVD apparatus for deposition of a silicon oxide based layer on a polymer substrate, comprising at least one linear hollow cathode plasma source, wherein each linear hollow cathode plasma source comprises at least one pair of electrodes connected to an AC, DC or pulsed DC generator; c. applying power to the linear hollow cathode plasma source such that the power density of the plasma is between 1 kW and 50 kW per linear meter of length of the linear hollow cathode plasma source; d. applying to the polymer substrate a gaseous precursor of an oxide of silicon and a reactive gas based on oxygen or an oxygen-containing derivative, wherein the gaseous precursor is applied at a flow rate of 50-700 sccm per linear meter of length of the linear hollow cathode plasma source, the gaseous precursor is injected between the electrodes of each electrode pair of the linear hollow cathode plasma source and between the two pairs of electrodes of the linear hollow cathode plasma source, and the reactive gas is applied at a flow rate of 1500-4000 sccm per linear meter of length of the linear hollow cathode plasma source, and the reactive gas is injected between the electrodes of the linear hollow cathode plasma source; Including, The PECVD apparatus is provided within a vacuum chamber maintained at a pressure of 0.005 to 0.025 Torr, and the ratio of power density per linear meter of length of the linear hollow cathode plasma source to the pressure within the vacuum chamber is 1.5 (kW / m) / mTorr or less.

2. A method for producing a silicon oxide-based layer on a polymer substrate as described in claim 1, wherein the ratio of the power density per linear meter of length of the linear hollow cathode plasma source to the pressure in the vacuum chamber is 0.2 (kW / m) / mTorr or more.

3. The reactive gas was pure O ２ and O ２ and a mixture of inert gas, and when a mixture of O 2 and an inert gas is selected, the ratio of O 2 to the flow rate of the inert gas in the mixture. ２ 3. A method for producing a silicon oxide based layer on a polymer substrate according to claim 1, wherein the ratio of the flow rates of:

4. The precursor of silicon oxide is SiH ４ 4. A method for producing a layer based on silicon oxide according to claim 1 on a polymer substrate, the layer being selected from the group consisting of TMDSO, HMDSO and HMDSO.

5. 5. A method for producing a silicon oxide based layer on a polymer substrate according to any one of claims 1 to 4, wherein power is applied to the linear hollow cathode plasma source such that the power density of the plasma is between 2 kW and 30 kW per linear meter of length of the linear hollow cathode plasma source.

6. A method for producing a silicon oxide-based layer on a polymer substrate as described in any one of claims 1 to 5, wherein power is applied to a linear hollow cathode plasma source such that the power density of the plasma is between 3 kW and 15 kW per linear meter of length of the linear hollow cathode plasma source.

7. A method for producing a silicon oxide based layer on a polymer substrate according to any one of claims 1 to 6, wherein the flow rate of the gaseous precursor is between 150 and 500 sccm per linear meter of length of the linear hollow cathode plasma source.

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