KR100490510B1 - Nozzle-injector for arc plasma deposition apparatus - Google Patents

Abstract

The nozzle-injector according to the present invention was designed and manufactured for plasma deposition using a wall stabilized arc torch as a plasma generator to coat a thin film. The design of the nozzle-injector controls the injection, ionization, reaction of the reagents, and these functions and determines the film deposition rate, film area, film composition, and film properties.

Description

Single nozzle-injector and surface treatment and deposition apparatus for arc plasma deposition equipment {NOZZLE-INJECTOR FOR ARC PLASMA DEPOSITION APPARATUS}

FIELD OF THE INVENTION The present invention relates to arc plasma deposition of protective coatings on various substrates such as glass, quartz, metal or metallized materials, and plastics, and particularly to high deposition rates of wear resistant, UV absorbing, or IR reflective transparent coatings. The present invention relates to a composite nozzle-injector for directing plasma flow and injecting reactive reagents into the plasma.

Due to the technical importance of thin films, various deposition methods have been developed.

Chemical vapor deposition (CVD) forms a solid film on the substrate surface by thermal activity and surface reaction of a gaseous reagent containing the desired thin film component. The energy required to pyrolyze the reactants is supplied by heating the substrate. In order to obtain a suitable reaction rate, the substrate is heated to a relatively high temperature in the range of about 500 ° F to 2000 ° F. Because of this temperature, this process cannot be applied to heat sensitive substrate materials.

Plasma enhanced chemical vapor deposition (PECVD) energizes reagents by discharge in the gas that forms the plasma in the deposition chamber. Generally, the substrate is immersed in the plasma. This deposition rate is typically low.

Polycarbonates are often chosen as engineering materials for grazing and optical applications because of their high impact strength, low density, optical transparency and good processability. However, polycarbonate materials are soft, lack wear resistance such as glass, and are sensitive to temperatures of about 300 ° F. According to the conventional studies, the silicon oxide film by plasma enhanced chemical vapor deposition (PECVD) can improve the wear resistance of polycarbonate and can be applied to grazing applications. However, conventional PECVD techniques that use silane and nitrogen dioxide as precursors are slow in reaction and therefore uneconomical and have a typical deposition rate of only about 0.05 microns per minute. Subsequent organosilicon precursors were used in PECVD for plasma-generating wear resistant polymer coatings, but the deposition rate was not significantly improved.

The process of the present invention provides films and layers that impart improved adhesion, thermal expansion suitability, radiation protection and abrasion resistance to articles made by the deposition process of the present invention. Attaching the protective film by plasma on hot and cold materials in the form of sheets, films and shaped substrates can be accomplished by the apparatus and methods disclosed herein.

Nozzle-injectors were designed and fabricated for plasma deposition of thin film coatings using wall-stabilized arc torch as a plasma generator. The design of the nozzle-injector controls the injection, ionization, and reaction of the reagents, and these functions determine the film deposition rate, film area, film composition, and film properties. When the nozzle-injector of the present invention is used in combination with the oxygen and siloxane of the reactant, a clear coating is formed on the polycarbonate and glass substrates at a deposition rate of about 30 microns per minute in the center. The film obtained from the siloxane greatly improves the wear resistance of the polycarbonate substrate. As a result of replacing the siloxane with a suitable organometallic reagent, another oxide film such as zinc oxide or titanium oxide was deposited on the plastic substrate. The coating is useful as an infrared or ultraviolet protective coating. The nozzle-injector of the present invention combines the reagent introduction of one or more injectors with the direction control of the nozzles in a single device.

Organic silicon compounds useful as monomers in arc plasma deposition processes using the nozzle-injector of the present invention include at least one silicon atom bonded to at least one carbon or at least one hydrogen atom, such as siloxane, silane acid and organic silicon. Silicon compounds and silanes.

The nozzle-injector of the present invention is suitable for use with various plasma generating devices, such as wall stabilized arc plasma torches having at least one water-cooled electrical insulating plate disposed between the anode and the cathode. Multi-plate wall stabilized arc devices are disclosed in US Pat. Nos. 4,948,485 and 4,957,062.

Waterfall cascades of multiple plates have been used as plasma sources for producing diamond-like carbon and plasma polymer coatings from hydrocarbon and organosilicon reagents. Deposition rates of several micrometers per minute were recorded. However, the coating area is narrow, its diameter is several centimeters, and the utilization of the material is about 20% or less. Depending on the conditions, a powder or powder coating may be formed outside the central deposition area. In order to make the coating technique practical and economical, it is important to enlarge the coating area, increase the deposition rate and minimize the formation of powders. The nozzle-injector according to the invention improves these.

Nozzle-injectors are designed to improve the coating performance of wall-stabilized arc plasma generators used in low temperature plasma deposition and polymerization methods. A shower-ring or slit-ring injector was assembled in the nozzle for the transfer of gas or vapor reagent. The position of the injector affects the degree of gas ionization, which affects the degree of reaction, thus affecting the stoichiometry and structure of the film, and ultimately its performance. The shape and size of the nozzle-injector also affects the degree of response, the film area, and the thermal load on the substrate. Using this nozzle-injector, an optically clear film of 30 cm x 30 cm area was deposited centrally at a rate of about 30 microns per minute. When such a nozzle-injector was not used, a powder-like coating was formed.

The construction and structure of the nozzle-injector comprises cylindrical and conical plasma channels and a two-stage conical channel having a cylindrical cross section therebetween. The divergence angle of the conical channel of the nozzle-injector ranges from about 0 ° to about 60 °. The diameter of the opening of the plasma channel in the nozzle base ranged from about 4 mm to 7 mm. Smaller diameter channels can be used for small objects. The length of the nozzle-injector ranged from 1.5 to 2.5 cm to control the volume of the area where the reaction can occur. The nozzle-injector may be of a single unitary configuration or may have a stainless steel body having an injector for introducing reagent into the plasma, a copper adapter for mounting the nozzle-injector to the plasma generator, and a downstream end of the body to be attached to the nozzle-injector. Parts such as extensions can be assembled that provide a suitable volume for the reaction zone. The injector can be made of a copper adapter for oxygen injection and the copper adapter is gold-plated to prevent oxidation. The modular design of the nozzle-injector affects the nozzle size and the gas injection location eliminates the need for a separate direction control and reagent injection unit.

Referring to FIG. 1, a schematic arc arc coating system includes a vacuum chamber reactor 1 having a plasma generator 2, a plasma processing chamber 4, a plasma inlet 6, and a nozzle-injector 8. It includes. The plasma generator receives a plasma gas such as argon through the gas supply pipe 3. The nozzle-injector 8 has an oxygen supply pipe 12 and a pair of reagent supply pipes 14 and 16 which can be operated individually or in combination. A vacuum pumping system (not shown) maintains low pressure in the plasma processing chamber 4 through the outlet 23. The substrate 20 to be coated is supported on a temperature control support 22 in the plasma processing chamber. The retractable shutter 24 is suitable for manual or automatic positioning by the handle 25 between the nozzle and the substrate in the path of the plasma jet.

Referring to FIG. 2, the plasma is generated by the flow of electrons flowing from the anode 2 through the electrically insulating plate 6 having the divergent central gas plasma channel to the water-cooled cathode 4. The apparatus has a plurality of anodes spaced at equal intervals, only one of which is indicated by reference numeral 2. The anode is water cooled. The anode is mounted in the anode housing 8 mounted on the water-cooled copper plate 6. The plate 6 is electrically insulated. Cooling water is supplied to the cooling water channel 9 through the water pipe 12. Cooling water for the cathode 4 is supplied by the water pipe 12 and flows through the conduit 5 in the cathode body. The vacuum in the processing chamber is partially maintained by sealing o-rings 15, 15a.

Plasma gas, for example argon, is supplied to the plasma generator through gas pipe 14. Oxygen is supplied to the nozzle through a tube 16 in communication with the circular conduit 18 and the slit injector 20. Reactive reagent is supplied via conduit 24 and conduit 22 which is transported to evenly spaced injection holes 26. As shown, the nozzle has an additional reagent supply tube 30 coupled to the conduit 32 and the injection hole 34. The second supply system can be used to supply other reactant or diluent gases to the active or reaction zone in the nozzle-injector.

The nozzle-injector has a diverging portion 40 which directs the plasma and the reactive material towards the coated substrate surface. The diverging portion 40 may be an integral part of the nozzle unit or may be designed as a removable extension. As shown, the extension has the same divergence as the portion of the nozzle immediately adjacent the cathode. The extension, for example, has a flaring or bell shaped opening, and therefore may differ from the shape and geometry of the cathode plasma channel and adjacent portions of the nozzle-injector.

The fastening screw 7 is one of several screws used to mount the positive electrode housing to the plate 6 and the negative electrode 4.

The present invention relates to an apparatus for surface treatment with a reagent injected into a plasma and for depositing an optically transparent adhesive film on a substrate surface, the apparatus comprising: a plasma generator having at least one anode and at least one cathode, operating at subatmospheric pressure Possible processing chambers, substrate support means disposed in the processing chamber to support the substrate, vacuum pumping means in communication within the chamber to deflate the processing chamber so that the pressure in the processing chamber is below atmospheric pressure, disposed on the cathode end of the plasma generator An apparatus is provided that includes a nozzle-injector device for directing a plasma jet towards a substrate and for transporting reagent into the plasma within the nozzle-injector.

The nozzle-injector comprises reagent transfer means for injecting reagent into the plasma when the plasma is generated from the plasma generator.

The nozzle injector is generally conical and the wide end is oriented towards the substrate. The length of the nozzle and the degree of divergence determine the volume in the apparatus. It also determines the time available for reaction and shaping of active species to treat or coat the surface of the substrate.

The reagent delivery means for injecting the reagent into the plasma is disposed at the narrow end of the nozzle-injector and has at least two separate annular injection conduits and dispensing means for uniformly introducing the reagent into the plasma.

Typically, the nozzle-injector extends from the cathode end of the plasma generator into the processing chamber. However, the nozzle-injector apparatus may be mounted at the cathode end of the plasma generator outside the vacuum chamber in communication with the interior of the vacuum via a suitable hermetic seal.

Experiment

Water-cooled waterfall arcs were used as plasma generators. The arc generator has a copper cathode separated by three tungsten-thoroxide needle-anodes by at least one or a series of electrically insulating copper disks. When argon flows through the bore of the arc torch, a DC voltage is applied to the electrode to generate a plasma. The plasma is expanded at a reduced pressure maintained by a vacuum pump through the nozzle-injector into the chamber. The nozzle-injector is heated to about 200 ° C. to avoid condensation of the organosilicon reagent at high boiling points. The coated substrate is supported on the jet axis by the metal stage at a suitable working distance from the cathode, for example about 15 to 70 cm. A retractable shutter is used to control the exposure of the plasma of the substrate.

In a typical deposition process, argon plasma is generated by the shutter at a location between the substrate and the nozzle-injector. Oxygen is introduced into the nozzle-injector to produce an oxygen / argon plasma. The shutter was removed and the substrate exposed for a short time before the silicon containing reagent was introduced into the halo from the oxygen injection site to begin deposition.

In Table 1, the effect of nozzle-injector on film area, deposition rate, and Taber abrasion resistance of the film was compared. The thickness of the film was about 2 microns. It has been found that conical nozzle-injectors (G273, G241) are most effective for large area coatings. If such a nozzle-injector is not used, a powder or powder coating is generally obtained.

TABLE 1

Effect of Nozzle-Injector on Coating Performance

^a cone, cone-cylindrical-cylindrical, cone-cylindrical

^b distance from anode

^c distance between substrate and anode

^d D4 = octamethylcyclotetrasiloxane, TMDSO = tetramethyldisiloxane, HMDSO = hexamethyldisiloxane

^e Polycarbonate with silicon hard coat layer

The working distance is the distance from the anode to the substrate.

The D4 flow rate was controlled by keeping the liquid temperature constant at 80 ° C.

In this particular experiment, the nozzle-injector has a body comprising two showerhead injection rings, an adapter for mounting the nozzle-injector to the cathode and injecting oxygen into the plasma, and an extension extending towards the substrate. The 25 ° 2-stage is a nozzle-injector with a cathode adapter injector extending from 4 mm to 11 mm, having a cylindrical cross section with a diameter of 11 mm, and the body being expanded to 25 °. A 25 ° -4 inch cone is a nozzle-injector that expands at an angle of 25 ° as a whole, with a cone length of 4 "and an oxygen injection adapter. A 40--4 inch cone has a nozzle-injector that is expanded 40 ° overall. 40 °-4 inch trombone, 40 °-except that the extension is further spread outward using a 4 inch cross-section cut by the bell of the trombone. It is a nozzle-injector similar to a 4 "cone.

According to the present invention, the silicon oxide film by plasma enhanced chemical vapor deposition (PECVD) can improve the wear resistance of the polycarbonate, can improve the characteristics of the grazing film of the film, the deposition rate using the organosilicon precursor Can be significantly improved, so that a film having improved adhesion, thermal expansion suitability, radiation protection, and wear resistance can be formed.

1 is a schematic cross-sectional view of a plasma arc deposition system having a vacuum chamber, a plasma generator, and a nozzle-injector according to the present invention;

2 is a cross-sectional view of a plasma generator and a nozzle-injector according to the invention.

Explanation of symbols for main parts of the drawings

1: vacuum chamber reactor 2: plasma generator

4 plasma processing chamber 6 plasma inlet

8 nozzle-injector 14, 16 reagent supply pipe

20: substrate 22: temperature control support

Claims (6)

In a single nozzle-injector for an arc plasma deposition apparatus, A plasma gas inlet, a cathode having at least one anode, a cathode having a divergent plasma channel, and a nozzle-injector mounted to the cathode, the nozzle-injector having a diverging channel extending from the cathode, and oxygen in the plasma near the cathode. And an arc plasma generator having an oxygen injector for injecting a gas and at least one reagent injector for injecting a reaction gas into the plasma when the plasma is expanded into the divergent channel. Single nozzle-injector for arc plasma deposition apparatus. An apparatus for surface treatment with a reagent injected in a plasma and for depositing an optically transparent adhesive film on a substrate surface, the apparatus comprising: A plasma generator having at least one cathode and at least one anode, a processing chamber operable at sub-atmospheric pressure, substrate support means disposed in the processing chamber to support the substrate, and for evacuating the processing chamber at sub-atmospheric pressure Vacuum pumping means in communication with the chamber, and a nozzle-injector device mounted on the cathode end of the plasma generator for directing the plasma jet towards the substrate and for transporting reagents in the plasma in the nozzle-injector; Surface treatment and deposition apparatus. The method of claim 2, The nozzle-injector comprises reagent transfer means for injecting reagent into the plasma when the plasma is emitted from the plasma generator. Surface treatment and deposition apparatus. The method of claim 2, The nozzle-injector is conical with a wide end facing the substrate. Surface treatment and deposition apparatus. The method of claim 2, The reagent delivery means for injecting reagent into the plasma is disposed at the narrow end of the nozzle-injector and has at least two separate injection conduits and annular dispensing means for uniform introduction of the reagent into the plasma. Surface treatment and deposition apparatus. The method of claim 2, The nozzle injector extends from the cathode end of the plasma generator into the processing chamber. Surface treatment and deposition apparatus.