Prior States of the Art At present known in the art are different types of an ion source designed for generation of linear ion beams.

The prior art ion source according to Patent GB 2070853A (HO1J 37/08,1981) comprises a ionization (discharge) chamber with an emission aperture in the form of a rectangle, a magnetic system and an ion-optic system (electrostatic) with an extracting (accelerating) electrode. For working gas ionization in this ion source two rod thermoemission electrodes of direct heating are used, with their parallel position opposite the emission aperture. Application of two thermoemission electrodes allows to reduce their operating temperature and, on account of this, increase the operation reliability and lifetime of a ion source.

Another prior art ion source with a linear beam described in Patent US 5089747A (HO1 J 27/02,1992) has a thermoemission electrode of a direct heating located in a separate ionization chamber filled with an inert gas. This chamber is used as a source of electrons to ionize the working gas. The main ionization chamber filled with working chemically active gas is connected with the ion source chamber through a small section aperture and an additional perforated electrode. The prior art ion source has a rather complex structure and power supply system to separate an area with a chemically active gas from a location zone of a hot thermoemission cathode.

A source of linear ion beam is also referred to the analogues of the invention claimed described in Patent US 4883969A (HO1 J 27/00,1989), which comprises an ionization chamber filled with a chemically active working gas, with an emission aperture in the form of a rectangle, a magnetic system generating a longitudinal magnetic field in the chamber, a rod thermoemission cathode of a direct heating locating opposite the emission aperture, and an ion-optic (electrostatic) system with an

accelerating electrode. To increase the thermoemission cathode lifetime emitting in the active gas medium an ion source construction is provided with a controlled supply of emission-active vapour to the ionization chamber. The emission active substance loss is compensated as a result of ion sputtering in the substance vapour depositing on the cathode.

However, the said ion sources cannot operate continuously and reliably with chemically active gases used as the working medium, since they include a thermoemission component inside the ionization chamber heated up to high temperatures. Besides, those ion sources do not allow to generate sufficiently long linear ion beams with an assigned uniformity of current density, since it is limited by a thermoemission cathode location relative to the emission aperture edges.

To produce a linear ion beam a SHF generator (magnetron) may be used, which is connected via a waveguide system and a decelerating system with the ionization chamber made of dielectric material (see, e. g., Patent US 4316090 A, HO1J 27/00, 1982). In the ionization chamber of this type ion sources with the help of an external magnetic system a magnetic field is produced, the parameters of which are chosen so as to provide a SHF power resonance absorption inside the chamber. On account of a heated component absence is the ionization chamber of a SHF source there appears a possibility to widely apply chemically active gases as a working medium. However, the ion source of the said type have a rather complex and expensive structure comprising a magnetron and they are characterized by low effectiveness of the power consumed.

The most closely analogous device to the invention patented is a plasma source with linear ion beam of a large extension described in Patent US 4859908 (HO1J 27/02, 1989). The prior art ion source inclues an ionization chamber with an emission aperture of a rectangular form, supply unit of the working medium to the chamber, a magnetic system producing a stationary non-uniform magnetic field inside the chamber, an input unit of high frequency power into the chamber cavity and an electrostatic system of ion extraction.

The HF (RF) electrodes of high frequency power input to the chamber are located on the chamber walls made of dielectric material in the prior art ion source. One of the generator electrodes is connected with the HF generator exiting oscillations of 13,56 MHz frequency, the second one grounded. The working gas pressure in the ionization chamber is maintained within a range of 10-3-104 Torr. The value of magnetic

induction in the ionization chamber is chosen within 10 to 200 Gs (in any case less than 500 Gs).

With the parameters indicated, the electron magnetizing and sufficiently effective HF power input into the ionization chamber, provided as a result of which a steady and spatially uniform plasma is generated.

However, this ion source structure does not allow to achieve the required uniformity of generated plasma and, accordingly, the current density uniformity in the developed linear ion beam source under condition of a longitudinal size increase of an emission aperture up to 300 mm and more. Iri this case the longitudinal size of the ionization chamber should be larger, the uniform plasma generating over the whole chamber volume.

Carrying out those conditions cannot be ensured observing optimum parameters from the viewpoint of providing effective HF power input into the discharge volume.

Violating optimum conditions of HF power input in the prior art structure of a ion source will evidently result in reliability and lifetime discharge of the device as well as power and gas efficiency decrease.

Summary of the Invention The present invention is based on the problem of developing a plasma source of linear ion beam having sufficient reliability, long lifetime, power and gas efficiency and, besides, allowing to obtain the extended linear ion beam of inert and chemically active substances with a high degree of current density uniformity along the beam cross- section.

The listed technical results are achieved on account of the fact that in the plasma source of linear ion beam, the structure of which comprises an ionization chamber with a rectangular emission aperture, a working medium input unit to the chamber, a magnetic system producing a stationary magnetic field inside the chamber, HF power input unit to the chamber cavity, the components of which are located on the chamber walls made of dielectric material, and an electrostatic system of ion extraction, according to this invention the magnetic system ensures generation of a magnetic field in the chamber, the induction value of which decreases from the chamber walls to its longitudinal axis of symmetry and in the direction of the emission aperture, the uniformity of a magnetic field provided along the longitudinal axis of symmetry of the ionization chamber along

the length of the emission aperture. However, to achieve an object of an invention a high frequency input unit is made in the form of two sections located on the opposite walls of he ionization chamber with a possibility of series or parallel connection to a high frequency generator, each section of the power input unit formed by current conductors connected in series an located in parallel on the side walls of the chamber along its emission aperture. The conductor ends in each sections are connected in series by terminating conducting elements, with a series electric circuit formed.

In another embodiment of the invention patented the listed technical results are achieved on account of the fact that in a plasma source of linear ion beam including an ionization chamber with a rectangular emission aperture, a working medium supply unit to the chamber, a magnetic system producing a stationary magnetic field inside the chamber, a high frequency power input unit to the chamber cavity, the components of which are located on the chamber walls made of a dielectric material, and an electrostatic system of ion extraction, according to the invention a magnetic system also ensures a magnetic field generation inside the ionization chamber, the induction value of which decreases from the chamber walls to its longitudinal axis of symmetry and in the direction of the emission aperture, the magnetic field uniformity provided along the longitudinal axis of symmetry of the ionization chamber along the emission aperture length. The input unit of high frequency power in the second embodiment of a ion source is effected in the form of at least two sections, either of which formed by current conductors located in parallel on the side walls of the chamber transverse to a longitudinal axis of symmetry of the emission aperture. The conductor ends in each section are connected in series by terminating conducting elements, with a series electric circuit formed. The sections are made with a possibility of series or a parallel connection to a high frequency generator and located on the chamber walls along the axis of symmetry of the emission aperture.

Both in the first and in the second embodiments of the ion source structure the following particular cases of embodiment are possible.

A preferred embodiment of an ion source structure is the one, in which a magnetic system is formed by at least a single magnetic core and permanent magnets located near the chamber walls.

The ionization chamber may be manufactured in the form of a rectangular parallelepiped.

There may be also an embodiment of the side walls of the chamber in the form of cylindrical surface, the axis of symmetry of which is parallel to a longitudinal axis of symmetry of the ionization chamber.

The electrostatic system electrodes of ion extraction can be made either concave or convex to select a certain area of linear beam cross-section and control its uniformity.

It is preferable, for uniform distribution of the ionized working medium in the chamber volume, that the supply unit of the working medium be located on the wall opposite the emission aperture.

In the preferred embodiment of the ion source structure the ionization chamber is fixed on the adjusting flange, in which the vacuum connector plugs of electric inputs are made. This structure embodiment allows to provide the compactness of a ion source and simplify its operation.

Brief Description of the Drawings The invention will be described with reference to its specific embodiment illustrated in the accompany drawings, wherein: Fig. l is a schematic view of a high frequency power input unit according to the first alternative embodiment of the ion source patented.

Fig. 2 is a schematic view of a high frequency power input unit according to the second alternative embodiment of the ion source patented.

Fig. 3 is a schematic side view of a plasma ion source designed according to the present invention with a partial longitudinal section.

Fig. 4 is the ion source view from the side of an electrostatic system of ion extraction (bottom view).

Fig. 5 is a cross-section of a plasma ion source scale up.

Preferred Embodiments of the Invention.

The linear ion beam source patented can be used in different structural embodiments as a part of technological plants, e. g., plasmochemical reactors and ion- beam plants, as well as a structural member of electric propulsion thrusters.

The description of two preferred alternative embodiments of a linear ion beam source designed to serve as a part of an ion-beam technological plant is given below.

In the first embodiment (see Fig. 1) a plasma ion source comprises an ionization chamber 1 made of dielectric material, e. g., quartz or glass in the form of a parallelepiped (in other structures of a plasma source of ions the side walls of chamber 1 can be made in the form of a cylindrical surface). The components of a high frequency power (HF power) input unit being a HF antenna to the chamber cavity are mounted on the walls of the ionization chamber 1.

The HF power input unit is formed by extended current conductors 2 located in parallel on the side walls of the chamber 1 along the emission aperture (see Fig. 1, in Fig. 3 HF power input unit is not shown to simplify the view). The conductor 2 ends are connected in series by terminating conducting elements 3, with a series electric circuit formed and connected via a matching system 4 with a high frequency generator 5 (HF generator). A preferred embodiment of a HF power input unit in reduced to practice as it is shown in Fig. 1 in the form of two sections located on the opposite side walls of the ionization chamber 1 and connected in series with a HF generator 5 via a matching system 4 (in other embodiments the HF power input unit sections can be connected in parallel to HF generator). To ensure an effective HF power input to the ionization chamber 1 the chamber walls are made of dielectric material except that part of the wall, in which there is a rectangular emission aperture. It should be noted that the dielectric material can be used only in those parts of the chamber 1 that are in the area of HF power input unit location (for effective HF power input in the chamber).

The electrostatic system 6 of ion extraction as a part of a plasma ion source is mounted on a rectangular emission aperture of the ionization chamber 1 and comprises (see Fig. 5) an emission electrode 7, an accelerating electrode 8 and an output grounded electrode 9 placed in series. The electrode apertures forming on the whole an emission aperture of a plasma source of linear ion beam can be of various forms. Fig. 4 shows a slit form of electrode apertures, the slit apertures are perpendicular to a longitudinal axis of symmetry of the ionization chamber 1, though the aperture embodiment may be of a circular shape.

To select a certain area of the linear ion beam cross-section and its uniformity the electrodes of the electrostatic system 6 may be of a different configuration: concave or convex. With a concave shape of electrode 7,8 and 9 the linear beam section increases and, accordingly, there appears a possibility of treating the surfaces the surfaces of a large size. With a convex shape of electrode 7,8 and 9 the area of the line beam cross-

section decreases, however value of ion beam current density) increases. This embodiment of an ion source can be used, e. g., with a longitudinal location of a ion source relative to a narrow band treated displaced with a sufficiently high speed in respect to the emission aperture.

The magnetic system of a plasma ion source consists of permanent magnet 10 assemblies located along the side walls of the ionization chamber 1 on the attachment components, with the help of which they are fixed to magnetic adjusting flanges 11 and 12 serving as a magnetic core (see Fig. 5). This embodiment of a magnetic system allows to generate a magnetic field inside the ionization chamber 1, the induction value of which decreases in direction from the chamber walls to its longitudinal axis of symmetry and in direction to the emission aperture. Besides, a magnetic system ensures the magnetic field uniformity along the longitudinal axis of symmetry of the ionization chamber 1 along its emission aperture length.

For uniform distribution of the magnetic field in the ionization chamber 1 cavity the extra permanent magnetic assemblies and/or extra magnetic cores may be used, which are symmetrically mounted at the face walls of the chamber (not shown in the drawing). This embodiment of a magnetic system allow to generate a magnetic field decreasing in direction from the walls of the ionization chamber 1 for uniformity increase of extracted linear ion beam. A required uniformity of a magnetic field along a longitudinal axis of symmetry of the ionization chamber 1 is ensured along its emission aperture length. In this case a magnetic isolation of face walls of the chamber 1 takes place and on account of that HF power usage efficiency increases for the working gas ionization and the charged particle concentration increases in the discharged volume along the emission aperture. It should be noted that electromagnet magnetizing coils can be also used as magnet field source.

The supply unit of a working medium to the ionization chamber is placed on the chamber wall located opposite the emission aperture. The unit comprises a gas distributor 13 located in the chamber cavity along the extended emission aperture (see Fig. 3 and 5). The gas distributor 13 is connected via the gas inlet 14 with the working medium supply system.

The ionization chamber 1 is fixed by fitting components 15 on the magnetic adjusting flange 12. Flanges 11 and 12 together with the chamber 1 are mounted on the vacuum chamber arrangement flange, which has vacuum connector plugs of electric

input (a detachable flange and connectors are not shown in the drawing). These connector plugs are designed for electrode 7,8,9 power supply.

In the second embodiment (see Fig. 2) a plasma ion source includes a HF power input unit comprising at least two sections, either of each formed by current conductors 2 placed in parallel on the side walls of the chamber 1 transverse to the axis of symmetry of the emission aperture. The conductor ends 2 in each section are connected in series by terminating conducting elements 3, with a series electric circuit formed and connected via a matching system 4 to a HF generator 5. The HF power input unit sections are located on walls of the chamber 1 along the longitudinal axis of symmetry of the emission aperture. Fig. 2 shows a concurrent connection of two sections, either of which comprises the conductors 2 connected in series and terminating elements 3, to the HF generator 5 via a matching system 4. Another embodiment is also possible of the HF power input unit, when the sections are connected in series to HF generator 5.

In other respects a plasma ion source of the second embodiment comprises the same structural members and units as those of a plasma of ions source of the first embodiment (see Figs. 3,4 and 5).

The plasma ion source both of the first and the second embodiment according to the above-described preferred samples of their implementation operates in the following manner.

The working medium, with argon used, is supplied to the ionization chamber 1 trough a gas inlet 14 (the ion source structure allows to use chemically active substances together with inert gases). In the chamber 1 with the help of permanent magnet assemblies 10 a stationary non-uniform magnetic field is generated, the induction value of which decreases from the walls of the chamber 1 to its longitudinal axis of symmetry and in direction to the emission aperture, in which the electrodes 7,8 and 9 of the electrostatic ion extraction system are mounted. A specified magnetic field distribution in the chamber 1 can be also ensured with the help of the other means known to specialists in this field of technology.

After the argon supply to the chamber 1 the HF generator 5 starts and the power with the aid of the HF power input unit connected to it via a matching system 4 is brought to the discharge volume. The HF power input unit of the above-described structure allows to excite an electrical high-frequency field component in the chamber cavity 1.

The effective HF power input is performed with two unit sections formed by conductors 2 located on the side walls of the chamber 1. The conductor ends 2 are connected in series by terminating conducting elements 3. A formed series circuit of either section envelopes the side walls of an extended ionization chamber 1 in the area of a desired-configuration magnetic field effect. A magnetic field generated by means of a magnetic system creates a magnetic isolation of all the chamber walls 1, except the wall with an emission aperture. The best result is achieved when the HF power input unit sections have the same impedance and equal distribution density of conductors over the wall surface of the chamber 1.

In the first embodiment (see Fig. 1) of a ion source the conductors 2 forming the HF power input unit sections are placed in parallel on the side walls of the chamber 1 along a longitudinal axis of symmetry of the emission aperture. In the second embodiment (see Fig. 2) the conductors 2 are placed in parallel on the side walls of the chamber 1 transverse to a longitudinal axis of symmetry of the emission aperture.

Both HF power input unit embodiments allow to perform an effective HF power input into a discharge volume along the whole length of an extended chamberl and, accordingly, along an extended emission aperture. Under the effect of a HF field electric component in the discharge chamber 1 a high frequency discharge is ignited. As a result plasma is generated. Ionization of the working medium takes place in the whole volume of the chamber 1, i. e., along its entire length of its extended emission aperture. This is achieved on account of HF power input unit embodiments according to the structural versions described above and a magnetic system usage following to generate a magnetic field of a specific configuration in the chamber 1 cavity. This effect presupposes a possibility of generating a linear ion beam with a desired uniformity of current density.

Increase of HF field power input effectiveness and, hence, increase of charged particle density and plasma temperature in the entire volume of the ionization chamber I is provided on account of magnetic field localization in the HF field generation area. It was established experimentally that increase of power and gas efficiency of a plasma generation in the chamber 1, and, consequently, linear ion beam generation is achieved in case of HF power input unit embodiment according structural alternative embodiments described above.

In case of using argon gas as a working medium the frequency of HF field generated in the chamberl is chosen depending on a required plasma concentration and

density of the ion current extracted within the range of 10 to 100 MHz. A maximum induction value of a stationary magnetic field is preferably set within a range of 0,01 to- 0,1 T. The value of HF power input into the chamber 1 is 20 W up to 1 kW.

In real conditions the value of linear ion beam current extracted from a ion source with an emission aperture size 50 mm x 300 mm may be amount to 300 mA. The current extracted can be increased on account of operating frequency increase of HF field generated.

Extraction and formation of a linear ion beam is effected in the ion source by an electrostatic ion extraction system 6 comprising three electrodes. This system of ion extraction realizes a well-known operating principle: « acceleration deceleration ». On electrodes 7,8 and 9of the electrostatic system 6 certain potentials are fixed by electric inputs through vacuum connection plugs made in the adjusting flange 12. The potential of a generated gas discharge plasma is given by an emission electrode 7. The electric field generated by emission 7, accelerating 8 and grounded 9 electrodes extracts the ions in the form of elementary beams from the chamber 1 through separate aperture made in them.

These beams are combined in a total beam and, as a result, a linear ion beam of a specific cross-section is formed determined by the sizes of a total emission aperture.

The size of a ion beam extracted from an ion source in the considered embodiments can amount to: in a longitudinal direction-up to 300 mm, in a transverse direction-up to 50 mm. The density of ion current can also be controlled from 0,05 up to 2 mA\cm2.

To ensure a possibility of the ionization chamber 1 dismount independent of other structural components of a plasma source of ions, the chamber 1 is mounted on a detachable adjusting flange. The plasma source of ions is mounted in the vacuum chamber of a technological plant. An electrostatic system of ion extraction is fixed on the adjusting flange 12. The magnetic system components are fixed by fitting elements between the adjusting flanges 11 and 12.

The embodiment described above and HF power input unit arrangement on the chamber 1 walls and a magnetic system usage providing generation of a stationary non- uniform magnetic field in the discharge volume with a certain gradient allows to reduce to practice an effective HF power input into a generated magnetoactive plasma over the entire chamber 1 volume. In applying a plasma source of linear ion beam accordingly to the embodiments described above the value of extended ion beam non-uniformity in

longitudinal and transverse directions did not exceed 5% at the target located at the distance of 300-400 mm from the electrostatic system of ion extraction.

The plasma ion source of a sufficient reliability, long lifetime, power and gas efficiency allows to generate an extended linear ion beam of inert and chemically active substances with a high uniformity of current density.

Industrial Application A plasma ion source with a linear ion beam (its alternatives) may be used in plasma technology, as a part of technological plants with gas discharge ion sources, e. g., implanters. The invention can find its application in different technological processes with ion beam usage, their longitudinal size up to 300 mm and more. A uniform linear ion beam of this size is widely used for treating semi-conductor materials, coatings, ion implantation, ion assistance, surface cleaning and material property alteration.

Though the invention patented has been described on the basis of preferred embodiments, the specialists in this field of technology understand that there may appear structural alternations of a ion source without deviation from the invention subject matter according to the claims presented.