RU2000354C1 - Unit for exposing articles to glow discharge - Google Patents

Abstract

FIELD OF THE INVENTION This invention relates to devices for treating articles with a glow discharge during vacuum coating. The device contains a current lead with a composite cathode (K) containing at least two closed plates (P) with parallel generators. One of P is made continuous, and the rest with holes (O) over the entire surface. The distance (P) between P is chosen to be at least twice P between the surface K and the negative glow zone. The size O and P between them is selected within P from the surface K to the negative glow zone. This embodiment K provides the occurrence of the hollow K effect in the cavity P, as well as an increased plasma density of the positive column of the glow discharge in the space from the side P with O, where efficient processing of the products is ensured. 1 ill.

Description

The invention relates to the processing of materials in a glow discharge during the application of vacuum coatings, in particular in microelectronics, optics, and the manufacture of consumer goods.

A device is known that contains a current lead and electrodes in the form of flat plates located in a vacuum chamber (see V. A. Brneshtein et al. On the effect of a glow discharge on a glass surface. Physics and Chemistry of Materials Processing, 1979, No. 4, p. .147), With the use of such electrodes, the processing efficiency is ensured when the products are placed in a narrow region of a negative glow discharge, parallel to the plane of the cathode. Under industrial conditions, the placement of products in the negative glow zone is very difficult as in the strength of the small thickness of the zone itself (not more than 1-2 mm)

and because of the Change in the position of the zone depending on the pressure in the chamber. In addition, for products of a non-flat configuration, their placement in the zone of negative glow is generally impossible, and therefore, to ensure uniform processing, they are placed in the plasma zone of the positive column of the glow discharge, where the energy of the ions and electrons of the discharge is much lower.

A device is known that contains a current lead and a cathode in the form of a spiral (see ed. St. USSR No. 388061). This design of the cathode makes it possible to more efficiently use the electrons emitted from the side surfaces of the spiral in the space between its turns, and thereby increase the ionization intensity of the gas and the atomization rate of the cathode material. However, when using such a cathode design

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there are the same disadvantages for processing the material as for the previous example. Besides . the more intense impact of the discharge provided by the cathode design is oriented both toward the workpiece and the opposite side to the workpiece, which reduces the efficiency of using the discharge power.

A device is described in the literature, containing a current lead and a hollow cylindrical electrode with holes in the side surface facing the workpiece (see Roikh I.L. and Koltunova A.N., Protective vacuum coatings on steel, M., 1971 ) In the described design of the electrode with the selected dimensions of the internal cavity, holes and the distances between them, the discharge has

concentrated exclusively in its internal cavity, and the impact indicators of the discharge on the workpiece are lower than for a flat electrode, because at the same voltage on the electrodes, both

Of their designs for the hollow electrode, the external and part of the discharge is a significantly shunted discharge in the cavity, thereby significantly reducing the processing efficiency of the product located on the outside of the cylindrical hollow electrode.

The aim of the invention is to provide an electrode that provides more efficient processing of products outside the negative glow zone in most of the chamber volume, by increasing the plasma density of the positive glow discharge column and the efficiency of using the discharge power.

The goal is achieved in that in a device for processing articles with a glow discharge containing a cathode with a current lead, a cavity and a zone of negative glow, the cathode cavity is formed by at least two closed plates with parallel generators, one of the plates being solid and the other with holes all over the surface. The distance between the plates is chosen equal to no less than twice the distance from the cathode surface to the negative glow zone, and the size of the holes and the distance between them are selected within the distance from the cathode surface to the zone

negative glow.

With this design of the cathode, the electrons emitted from the inner parallel surfaces of the plates begin to oscillate in the cavity between the solid plate and are continuous5

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At the selected distance between the plates, the electrons manage to accumulate enough energy to ionize the gas until the direction of their movement changes. As a result, in the process of oscillations, each electron provides multiple ionization in the space between the plates, which causes an avalanche-like increase in the number of electrons themselves, and as a result, an additional increase in the degree of ionization of the gas in this space. As a result, the discharge current increases sharply (up to 10 times). With the selected size of the holes in the plates, it is possible for electrons to exit the trap formed by the opposing electric fields of the parallel plates. At the selected distance between the holes, the condition of maximum exit of electrons to the zone of the workpiece is ensured. In this way, an increased current flows through the positive column of the glow discharge from the side of the glow discharge plates. The increase in current is accompanied by a significant increase in the intensity of the gas glow and the degree of influence of the plasma of the positive column of the glow discharge on the workpiece.

The drawing shows a device for processing products with a glow discharge in the case of using two plates in parallel planes.

The current lead 1 is connected to a continuous plate 2 and plate 3 with holes fixed to each other by means of stops 4 at a selected distance. An electron path 5 crosses the negative glow zone 6 between the plates and enters the space where the workpiece 8 is located. The walls of the chamber 9 serve as the second electrode.

Negative potential is supplied through current lead 1 to plates 2 and 3 with a limiter 4. Electrons emitted by secondary electron emission from the inner surface of one of the plates are accelerated in the direction of the opposite plate. When the electrons reach ionization energy, at the moment of their collision with gas atoms, it is possible to ionize these atoms, as a result of which additional electrons appear. When the electrons move further, they are inhibited by the oncoming field of the opposite plate, stop and begin to move in the opposite direction, providing new acts of ionization, and so on, until they fly out of this semi-enclosed space through the holes of the plate 3 along the path 5. As a result of these factors roiskhodit effective ionization of gas with the formation zone of the negative glow in the cavity between the plates and an avalanche multiplication of electrons. The discharge current sharply increases, the hollow cathode effect arises due to the ascension of a significant number of fast electrons inside the cavity, which, breaking out through the holes of the plate 3. provide an increased plasma density of the positive column of the glow discharge in the vast space 7. oriented perpendicular to the cathode plane in direction of plate 3 with holes. Products 8 of various configurations are easily housed in this space. The use of the walls of the chamber 9 as the second electrode (anode) has practically no effect on the dimensions and directivity of the space 7

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Claims (3)

with plasma of increased density. The formation of the discharge from the side of the free surface of the continuous plate 3 is practically absent, which ensures the efficient use of the discharge power for surface treatment of the product. SUMMARY OF THE INVENTION 1. A device for treating articles with a glow discharge containing a hollow cathode with a negative glow zone and a current lead, characterized in that the cathode is formed by at least two closed plates with parallel generatrixes, one of the plates being solid and the other having holes mi across the surface 2. The device pop. 1. differs from that. that the distance between the plates is not less than twice the distance from the cathode surface to the zone of negative luminescence. 3. Device pop. 1, characterized in that the diameter of the holes and the distance between them are within the distance from the surface of the cathode to the zone of negative glow.