MXPA06013380A

MXPA06013380A - Plasma enhanced chemical vapor deposition of metal oxide.

Info

Publication number: MXPA06013380A
Application number: MXPA06013380A
Authority: MX
Inventors: Dmitry P Dinega; Christopher M Weikart
Original assignee: Dow Global Technologies Inc
Priority date: 2004-05-20
Filing date: 2005-05-20
Publication date: 2007-01-23
Also published as: CA2562914A1; KR20070012718A; BRPI0510823A; SG151324A1; WO2005113856A1; CN1957109A; JP2007538159A; RU2006145309A; EP1756329A1

Abstract

A metal oxide coating can be applied to a substrate (60) at a relatively low temperature and at or near atmospheric pressure by carrying a metal oxide precursor (10) and an oxidizing agent through a corona discharge (40) or a dielectric barrier discharge to form the metal oxide and deposit it onto to the substrate.

Description

Electrically conductive emissivity in a glass substrate comprising: 1) depositing a reflective metal layer on the substrate, then 2) reactive deposition by depositing a layer of metal oxide on a reflective metal layer in the presence of a cleaner of oxygen, and then 3) a thermal treatment of the substrate at a temperature of 400 ° C to 720 ° C. The metal oxide is described as being an oxide of tin, zinc, tungsten, nickel, molybdenum, manganese, zirconium, vanadium, niobium, tantalum, cerium or titanium or mixtures thereof. Woo in US Patent No. 6,603,033, describes the preparation of organotitanium precursors that can be used for the deposition of organic metal chemical vapor (MOCVD). The thin film of titanium oxide was described as being formed on a glass substrate that was heated to a temperature of 375 ° C to 475 ° C. In contrast, Hitchman et al., In WO 00/47797, discloses the deposition of thin films of rutile titanium dioxide in a variety of substrates including glass, sapphire, steel, aluminum and magnesium oxide, at low as 268 ° C, but at reduced pressures (0.00136 kg / cm2 (1 torr)). As the technique suggests, metal oxide deposits in temperature-resistant substrates such as glass can be made at relatively high temperatures without degrading the glass. However, significantly lower temperatures would be required to deposit a metal oxide on a plastic substrate.

Furthermore, for practical reasons, it would be desirable to carry out said deposit at or near atmospheric pressure. Therefore, it would be advantageous to discover a method for depositing the metal oxide on a plastic substrate at a temperature below the glass transition temperature of the substrate, preferably at or near atmospheric pressure. Brief Description of the Invention The present invention relates to a need in the art, providing a method comprising the steps of 1) carrying a metal oxide precursor through a corona discharge or a dielectric barrier discharge in the presence of an oxidizing agent to convert the precursor to a metal oxide by the improved deposition of the chemical vapor plasma (PECVD), and 2) to deposit the metal oxide on the substrate. Optionally, precursors sensitive to the PECVD of the organosiloxane SiOx coating can be deposited consecutively or co-deposited producing multilayer metal oxides and / or composite compositions on the substrate. Brief Description of the Drawings Figure 1 illustrates a corona discharge method of generating and depositing a metal oxide on a substrate. Figure 2 illustrates a dielectric barrier discharge apparatus. Detailed Description of the Invention The present invention is a method for depositing a metal oxide on a substrate using the improved reservoir of the chemical vapor plasma. In a first step, an organometal precursor is carried through a corona discharge or a dielectric barrier discharge in the presence of an oxidation agent and preferably a carrier gas. The discharge converts the precursor into metal oxide, which is deposited on a substrate. As used in the present description, the term "metal oxide precursor" refers to a material that has the ability to form a metal oxide when subjected to an improved chemical vapor plasma (PECVD) deposit. Examples of suitable metal oxide precursors include diethyl zinc, dimethyl zinc, zinc acetate, titanium tetrachloride, dimethyltin diacetate, zinc acetylacetonate, zirconium hexafluoroacetylacetonate, zinc carbamate, trimethyl indium, triethyl indium, cerium ( IV) (2,2,6,6-tetramethyl-3,5-heptanedione) and mixtures thereof. Examples of metal oxides include zinc oxides, tin, titanium, indium, cerium and zirconium, and mixtures thereof. An example of a particularly useful mixed oxide is tin-indium oxide (ITO), which can be used as a transparent conductive oxide for electronic applications. The method of the present invention can be advantageously carried out using the well-known corona discharge technology as illustrated in Figure 1a. Referring now to Figure 1a, the upper space of the precursor (10), as a carrier of the precursor and the oxidation agent are flowed into a jet (20) through a first gas inlet (30) and a corona discharge (40) - which decomposes the gas into two electrodes 50 (a) and 50 (b) - to form the metal oxide, which is deposited on the substrate (60), preferably a plastic substrate that is heated to impart order to it. If a plastic substrate is used, the plastic is advantageously maintained at a temperature close to its glass transition temperature, preferably not exceeding 50 ° C above its glass transition temperature before or during the deposition of the oxide. of metal. The method is preferably carried out at or near atmospheric pressure, generally in a range of 0.952 kg / cm2 to 1.088 kg / cm2 (700 to 800 torr). The vehicle for the precursor is usually nitrogen, helium, or argon, with nitrogen being preferred; the oxidation agent is a gas containing oxygen, such as 02, N20, air, 03, C02, NO, or N204, with air being preferred. If the precursor is highly reactive with the oxidizing agent - for example, if the precursor is pyrophoric - it is preferred to separate the oxidation agent from the precursor, as illustrated in Figure 1b. According to this scheme, the vehicle and the precursor are flowed through a second gas inlet (70) located just above the corona discharge (40) and the oxidation agent flows through a first intake (30). ). In addition, a second carrier can be used to further dilute the concentration of the precursor prior to introduction into the jet (20). The oxidation agent may not need to be provided in an affirmative manner to the corona discharge region or the dielectric barrier discharge in the region that is available through ambient air. The corona discharge (40) is preferably maintained at a voltage in the range of about 2 to 20 kV. The distance between the corona discharge (40) and the substrate (60) generally varies from about 1mm to 50mm. The precursor can be supplied to the jet by partially filling a container with precursor to leave an upper space and sweeping the upper space with the carrier inside the jet (10). The container can be heated, if necessary, to generate the desirable vapor pressure for the precursor. Where the precursor is moisture - or air sensitive or both, it is preferred to keep the precursor in a container substantially free of oxygen and free of moisture. The dielectric barrier discharge, also known as "silent" discharge and "atmospheric pressure incandescence" discharge, can also be used to carry out the process of the present invention. Figure 2 illustrates a schematic view of a dielectric barrier discharge apparatus (100), which comprises two metal electrodes (110 and 120) in which at least one is coated with a dielectric layer (130) superposed by a substrate (150). The space between the electrodes (110 and 120) is generally in a range of 1 to 100 mm, and the applied voltage is in the order of 10 to 50 kV. The plasma (140) is generated through a series of micro-arcs that last at least about 10 to 100 ns and are randomly distributed in space and time. The concentration of the precursor in the total gas mixture (the precursor, the oxidizing agent and the carrier gas) is preferably in the range of 10 ppm to 1% v / v. The flow range of the precursor is preferably in a range of 0.1 to 10 sccm and the flow range of the oxidizing agent is preferably in a range of 10 to 100 scfm (2.7 x 105 to 2.7 x 10 6 sccm). The thickness of the coating on the substrate depends on the application but is generally in a range of 10 nm to 1 m. The substrate is not limited, but preferably is a plastic, examples of which include polycarbonates, polyurethanes, thermoplastic polyurethanes, poly (methyl methacrylates), polypropylenes, low density polyethylenes, high density polyethylene, ethylene-alpha-olefin copolymers, (co) styrene polymers, styrene-acrylonitrile copolymers, polyethylene terephthalates and polybutylene terephthalates. The method of the present invention can provide UV blocking coatings for plastic substrates at low temperature and at or near atmospheric pressure. The following examples are for purposes of illustration only and are not intended to limit the scope of the present invention.

Example 1 - Tin Oxide Deposit in a Polycarbonate Substrate The dimethyltin diacetate was placed in a closed precursor tank and heated to a temperature of 62 ° C. Since nitrogen was passed through the reservoir at 3000 sccm and combined with an air current passed at 15 scfm (420,000 sccm). The gas line leaving the tank was heated to a temperature of 70 ° C. The total gas mixture was passed through a corona discharge PLASMA-JET® (available from Corotec Corp., Farmington, CT., Electrode separation of 1 cm) directed on a polycarbonate substrate. After 10 minutes, a clear monolithic coating of tin oxide was formed as tested by the electron scanning microscope and x-ray photoelectron spectroscopy (XPS). Example 2 - Deposit of Titanium Oxide in a Polycarbonate Substrate Titanium tetrachloride was placed in a closed reservoir of the precursor and cooled to a temperature of 0 ° C. Nitrogen gas flowed through the tank to 600 sccm and combined with a stream of dry air (TOC grade) passed to 20 scfm (570,000 sccm). The total gas mixture was passed through the directed plasma jet apparatus into a polycarbonate substrate. After 8 minutes, a clear monolithic coating of titanium oxide was formed as tested by the XPS electron scanning microscope. Example 3 - Deposit of Zinc Oxide in a Polycarbonate Substrate Diethyl zinc was placed in a closed precursor reservoir. The nitrogen gas was passed through the tank at 150 sccm and combined with another nitrogen jet passed at 3500 sccm. The gas mixture was introduced into an air plasma stream generated by the plasma jet apparatus and directed onto the polycarbonate substrate. The air flow range (TOC grade) was 20 scfm (570,000 sccm). After 10 minutes, a clear coating of zinc oxide was formed as tested by the electron scanning microscope and the XPS. Example 4 - Zinc Oxide Deposit Absorbing UV Beams in a Polycarbonate Substrate Diethyl zinc was placed in a closed precursor reservoir.

Nitrogen gas was passed through the tank at 100 ° C and combined with another stream of nitrogen passed at 3800 sccm. The gas mixture was introduced into a jet of air plasma generated by the plasma jet apparatus and directed onto the polycarbonate substrate. The range of air flow (low humidity air conditioning) was 15 scfm (570,000sccm). The energy applied to the electrodes was 720 W and the distance from the jet to the substrate was 20 mm. After 15 minutes, a clear coating of zinc oxide of a thickness of approximately 0.6 μ? T was formed. on a polycarbonate sheet as tested by the electron scanning microscope and the XPS. During deposition, the polycarbonate sheet (Tg = 150 ° C) was heated to a temperature of 180 ° C to induce the crystallinity of the coating, as tested by XRD analysis. The zinc oxide coatings were intact after 1000 hours of QUV-B wear tests according to the ASTM G53-96 standard. The coatings showed a yellow Delta Delta Nebulosity < 5 and < 18% and 85% light transmission and a UV absorption cutoff of approximately 360 nm. Example 5 - Deposit of Zinc Oxide Using a Dielectric Barrier Discharge in a Polycarbonate Substrate. Diethylzinc was placed in a closed tank. Nitrogen gas was passed through the tank at 150sccm and combined with another stream of nitrogen at 60scfm. The gas mixture was introduced downwards and mixed with air before leaving the electrode inside the discharge zone, which makes contact with the plicarbonate substrate. The air flow range was 11357 sccm. The energy applied to the electrodes was 1000W and the distance from the electrode to the substrate was approximately 4mm. After 10 minutes, a clear coating of zinc oxide was formed on a polycarbonate film as tested by the electron scanning microscope and the XPS. Example 6 - Deposit of Multiple Layer Coatings of SiOxCyHz or SiOx / Zinc Oxide An organosiloxane coating similar to the VPP according to US Patent No. 5,718,967, was deposited on a polycarbonate substrate. The tetramethyldisiloxane precursor flowing at 6000sccm is mixed with N20 in a flow range of lOOOsccm. The gas mixture was introduced into a nitrogen plasma jet generated by the plasma jet apparatus and directed onto the polycarbonate substrate. The nitrogen gas equilibrium is passed through a flow rate of 25scfm. The energy applied to the electrodes was 78W, the distance from the jet to the substrate was 5 mm. A Zinc Oxide coating was deposited on the top of organosiloxane coating according to Example 4. Optionally, another layer of organosiloxane is deposited on top of the Zinc Oxide layer.

Claims

CLAIMS 1. A method which comprises the steps of 1) carrying a metal oxide precursor through a corona discharge in the presence of air as an oxidizing agent to convert the precursor to a metal oxide by the improved deposit of vapor plasma of chemical and 2) deposit the metal oxide on a substrate. The method as described in claim 1, characterized in that the metal oxide precursor is brought through a corona discharge at or near atmospheric pressure. The method as described in claim 2, characterized in that the substrate is a plastic that is heated to a temperature that does not exceed its glass transition temperature by more than 50 ° C. 4. The method as described in claim 3, characterized in that the metal oxide precursor is selected from the group consisting of diethyl zinc, dimethyl zinc, zinc acetate, titanium tetrachloride, dimethyltin diacetate, zinc acetylacetonate, zirconium hexafluoroacetylacetonate, trimethyl indium, triethyl indium, cerium (IV) (2,2,6,6-tetramethyl-3,5-heptanedione) and zinc carbamate. The method as described in claim 3, characterized in that the metal oxide precursor is selected from the group consisting of diethyl zinc, titanium tetrachloride, trimethyl indium, triethyl indium and dimethyltin diacetate. 6. The method as described in claim 3, characterized in that the inert gas carrier is used for the precursor. The method as described in claim 3, characterized in that the inert gas carrier is nitrogen. The method as described in claim 2, characterized in that the metal oxide is selected from the group consisting of zinc oxide, titanium oxide, tin oxide, zirconium oxide and cerium oxide. 9. The method as described in claim 2, characterized in that the metal oxide is indium-tin oxide. 10. A method for depositing a metal oxide coating on a plastic substrate, which comprises the steps of 1) carrying a metal oxide precursor and an oxidizing agent which is air through a corona discharge for convert them by the enhanced deposit of chemical vapor plasma from the precursor into metal oxide and 2) deposit the metal oxide on a plastic substrate, where the discharge is maintained at or near atmospheric pressure and the substrate is heated to a temperature that does not exceed 50 ° C above its glass transition temperature. A method as described in claim 9, characterized in that the metal oxide is deposited simultaneously or consecutively with the improved deposit of chemical vapor plasma from another material on a plastic substrate. 12. The product manufactured by the method as described in claim 11. 13. The product as described in claim 12, characterized in that the other material is an organosiloxane or a deposit of SiOx.