KR19990007319A - Nozzle-Injectors for Arc Plasma Deposition Devices - 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 spraying, ionization, reaction of the reagents, and their functions and determines the film deposition rate, film area, film composition, and film properties.

Description

Nozzle-Injectors for Arc Plasma Deposition Devices

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. A combination nozzle-injector for injecting a reactive reagent into a plasma for high deposition rate.

Due to the technical importance of thin films, several 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 components of the thin film. The energy needed to pyrolyze the reactants is provided by heating the substrate. The substrate is heated to a relatively high temperature in the range of about 500 ° F. to 2000 ° F. for moderate reaction rates. These temperatures make the implementation of heating the temperature sensitive substrate material difficult.

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

Polycarbonates are often chosen as engineering materials for grading and optical use because of their impact strength, low density, light transparency and good processability. However, the polycarbonate material is soft, lacks glassy abrasion resistance, and is 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 the polycarbonate, and will be suitable for carrying out the grading of the film. However, conventional PECVD techniques that use silane and nitrogen dioxide as precursors are uneconomical because of their slow reaction rate and typically have deposition rates on the order of about 0.05 microns per minute. Subsequent organosilicon precursors were used in PECVD for plasma-generating wear resistant polymer coatings, but deposition rates did not improve significantly.

The process of the present invention provides films and layers that provide adhesion enhancement, thermal expansion suitability, radiation protection, and wear resistance to articles made by the deposition process of the present invention. Deposition of the protective film by plasma on hot and cold materials in the form of sheets, films and molded substrates can be accomplished by the devices and methods disclosed herein.

The nozzle-injector was designed and manufactured for plasma deposition using a wall-stabilized arc torch as a plasma generator to deposit a thin film. The design of the nozzle-injector in turn controls spraying, ionization, reaction of the reagents, and their functions, and determines film deposition rate, film area, film composition, and film properties. Using a nozzle-injector according to the invention using oxygen and siloxane as a reagent, a clean film is formed on the polycarbonate and glass substrate at a deposition rate of about 30 microns per minute in the center. The siloxane derived coating improves the wear resistance of the polycarbonate substrate. 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 applied as an infrared or ultraviolet protective coating. The nozzle-injector of the present invention combines the nozzle introduction function and the nozzle introduction function of one or more injectors in a single device.

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

The nozzle-injector of the present invention is suitable for use in a variety of plasma generating devices, such as wall-stabilized arc plasma torches having at least one water cooled electrical insulation 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.

Multi-plate cascade arcs were used as plasma sources to make diamond-like carbon and plasma polymer coatings into hydrocarbons and organic silicon reagents. Deposition rates of several micrometers per minute were recorded. However, the coating area is narrow, its diameter is several centimeters, and the metal availability 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 powder formation. The nozzle-injector according to the invention achieves these improvements.

Nozzle-injectors are designed to improve the coating performance of wall-stabilized arc plasma generators used in low temperature plasma deposition and polymerization methods. Shower-ring or slit-ring injectors were made with nozzles for the transport of gas or vapor reagents. The position of the injector affects the degree of gas ionization, which in turn affects the chemical speculative structure and ultimate performance of the coating. The shape and size of the nozzle-injector also affects the degree of reaction, film area, and 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. If such a nozzle-injector was not used, a powdery film was formed.

The configuration and structure of the nozzle-injector has both cylindrical and conical plasma channels and two stage conical channels with 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. This nozzle-injector may be of a single unitary configuration or has a stainless steel main body having an injector for introducing a reagent into the plasma, a copper adapter for mounting the nozzle-injector to the plasma generator, and a nozzle-attached to a downstream end of the main body. Injectors can be assembled with extensions, such as extensions, 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 position eliminates the need for separate directional control and prototype injection units.

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: prototype feed pipe

20: substrate 22: temperature control support

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. The vacuum pumping system, not shown, maintains a low pressure in the plasma processing chamber 4 through the outlet 23. The coated substrate 20 is supported on the 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 through the electrically insulating plate 6 having the divergent central gas plasma channel from the cathode 2 to the water cooled anode 4. The apparatus has a plurality of cathodes spaced at equal intervals, only one of which is indicated by reference numeral 2. The cathode is water cooled. The cathode is mounted in a cathode housing 8 which is mounted on a 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 not shown in the cooling water channel 9. Cooling water for the anode 4 is supplied by the water pipe 12 and flows through the conduit 5 in the anode 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 feed tube 30 coupled to the conduit 32 and the injection hole 34. The incidental supply system can be used to deliver another reactant or diluent gas 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. 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 degree of divergence as the portion of the nozzle immediately adjacent to the anode. The extension may vary in shape and geometry of the anode plasma channel and adjacent portions of the nozzle-injector, for example to have a morning glory or bell shaped mouse.

The set screw 7 is one of several screws used to mount the cathode housing to the plate 6 and the anode 4.

The present invention provides a plasma generator having one or more cathodes and at least one anode, a processing chamber operable at sub-atmospheric pressure, substrate support means disposed within the processing chamber to support the substrate, and the pressure of the processing chamber at sub-atmospheric pressure. Vacuum pumping means preferably in communication with the chamber to deflate the processing chamber, and a nozzle-injector device disposed on the anode end of the plasma generator to direct the plasma jet towards the substrate and to carry the reagent into the plasma in the nozzle-injector The present invention provides a device for surface treatment and deposition of an optically smooth adhesive film on a substrate surface by a reagent sprayed into the plasma.

The nozzle-injector comprises a reagent transfer means for injecting the 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 within the device. It also determines the time suitable for the reaction and shaping of the active species to treat or coat the surface of the substrate.

The reagent delivery means for injecting the reagent into the plasma is arranged 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.

In general, the nozzle-injector extends from the anode end of the plasma generator into the processing chamber. However, the nozzle-injector apparatus was mounted at the anode end of the plasma generator outside the chamber in communication with the interior of the volume via an appropriately hermetically sealed volume.

Experiment

Water-cooled waterfall arcs were used as plasma generators. The arc generator has a copper anode separated by a tungsten thorium 3 needle-cathode 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 can be heated to about 200 ° C. to avoid condensation of the organic silicon reagent at high boiling points. The coated substrate is supported on the jet axis by a metal stage at a suitable working distance from the anode, 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 the oxygen / argon plasma. The shutter was retracted and the substrate was exposed for a short time before the silicon-containing reagent was introduced downward from the oxygen injection site into the initial deposition state.

In Table 1, the effects of film area, deposition rate and Taber abrasion resistance of the film are compared. The coating was about 2 microns thick. It has been found that conical nozzle-injectors G273 and G241 are most effective for large area coatings. If no such nozzle-injector is used, a powdery or powdery coating is usually obtained.

Effect of Nozzle-Injector on Coating Performance G273 G241 G187 G204 G147 G123 Nozzle-Injector Type ^a Conical Conical Conical Conical Cone-cylinder-conical Cone-cylindrical Divergence Angle (degrees) 40 40 25 25 33 50 Diameter of cylindrical cross section (cm) - - - - 1.1 3.0 Total nozzle length (cm) 16 16 21 13.5 13.5 9.5 Oxygen supply position ^b (cm) 0.5 0.5 4 4 4 4.5 Siloxane feed position ^b (cm) 5 5 5 5 5 6 Working distance ^c (cm) 25.5 25.5 33 23 38 38 Board MR7 Glass MR7 ^e MR7 ^e PC MR5 ^e Si tense ^d D4 TMDSO TMDSO TMDSO HMDSO HMDSO Argon flow rate (l / min) 1.0 1.0 1.5 1.5 2.0 2.0 Oxygen flow rate (l / min) 0.8 0.8 0.8 0.8 0.06-0.6 0-0.93 Siloxane flow rate (l / min) 0.27 0.18 0.18 0.18 0.11 0.18 Chamber pressure (torr) 0.15 0.15 0.15 0.15 0.18 0.22 Deposition Rate (μm / min) 29 9 10 10 4 10 Clean film area (cm dia) 43 43 15 7.5 10 7.5 △ haze (%) at 1000 cycles 3 - 7 3 6 10

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 the particular experiment described above, the nozzle-injector comprises a main body having two showerhead injection rings, an adapter for mounting the nozzle-injector to the anode and injecting oxygen into the plasma, and an extension extending toward the substrate. The 25 ° 2-stage is a nozzle-injector with an anode adapter injector extending from 4 mm to 11 mm, having a cylindrical cross section with a diameter of 11 mm, and the main body being inflated 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 four lengths and an oxygen injection adapter. The 40 ° -4 inch cone is a nozzle-injector that is expanded 40 ° overall, with an anode adapter to which oxygen is injected, and a 4 inch long cone extension. A 40 ° -4 inch trombone is a nozzle-injector similar to a 40 ° -4 cone, except that the extension is further spread outward using a 4 inch cross section cut by the bell of the trombone.

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

Claims (6)

A single nozzle-injector for an arc plasma deposition apparatus comprising an arc plasma generator having a plasma gas inlet, an at least one cathode, an anode having a divergent plasma channel, and a nozzle-injector mounted to the anode, the nozzle extending from the anode. A single nozzle-injector having a divergent channel, an oxygen injector for injecting oxygen into the plasma near the anode, and at least one reaction injector for injecting a reactant gas into the plasma when the plasma is expanded into the divergent channel. A plasma generator having one or more anodes and at least one cathode, a processing chamber operable at sub-atmospheric pressure, substrate support means disposed in the processing chamber to support the substrate, and the processing chamber to air at sub-atmospheric pressure A vacuum pumping means in communication with the processing chamber to subtract the nozzle, and a nozzle-injector device mounted on the anode end of the plasma generator for directing the plasma jet towards the substrate and transferring the reagent to the plasma in the nozzle-injector; A device for surface treatment and deposition of an optically clear adhesive film on a substrate surface by means of a reagent sprayed into the substrate. The method of claim 2, The nozzle-injector comprises a reagent transfer means for injecting a reagent into the plasma when the plasma is emitted from the plasma generator. The method of claim 2, The nozzle-injector is conical device with a wide end oriented towards the substrate. The method of claim 2, An apparatus for transporting a reagent into the plasma is provided at a 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. The method of claim 2, The nozzle injector extends from the anode end of the plasma generator to the processing chamber.