WO2007023489A1

WO2007023489A1 - A plasma emitter and methods utilizing the same

Info

Publication number: WO2007023489A1
Application number: PCT/IL2006/000957
Authority: WO
Inventors: Zvi Porat
Original assignee: Zvi Porat
Priority date: 2005-08-21
Filing date: 2006-08-17
Publication date: 2007-03-01
Also published as: IL170401A

Abstract

The present invention discloses in cathodic arc plasma, a system of obtaining a high current emission of hot electrons having temperature equivalent to 10 eV to 15 eV, by an Arc Plasma Emitter and method utilizing the same. The system is especially adapted for polishing gemstone, and growing a 3D crystal by the same.

Description

A PLASMA EMITTER AND METHODS UTILIZING THE SAME

FIELD AND BACKGROUND OF THE INVENTION

The invention generally relates to a plasma emitter and to methods utilizing the same. More specifically, the invention relates to an enhanced plasma emitter and to a method of polishing a gemstone, and growing a 3D crystal by the same.

An ion source which ionizes gas molecules and then focuses, accelerates, and emits those ionized gas molecules and/or atoms in a beam toward a substrate is utilized in various sputtering techniques, substrate cleaning, co-deposition etc. Various cold cathode units were presented in the art, such as US patent 5,569,976 "Ion emitter based on cold cathode discharge", US patent 5,130,607 "Cold-cathode, ion- generating and ion-accelerating universal device" and US patent 4,886,969 "Cluster beam apparatus utilizing cold cathode cluster ionizer". Nevertheless, a cost effective method and means for obtaining a high current source of electrons utilizing a cold cathode unit for either polishing an object (e.g., gemstone), and growing a 3D crystal is still a long felt need.

BRIEF DESCRIPTION OF THE FIGURES

In order to understand the invention and to see how it may be implemented in practice, a preferred embodiment will now be described, by way of non-limiting example only, with reference to the accompanying drawing, in which figure 1 schematically illustrates a Hall Current Layer model as was suggested in the art; figure 2 schematically illustrating ions reaching the boundary layer and are electrostatically reflected, while electrons maintain their drift along the Hall Current Layer may penetrate through a slit in the anode of the emitter of electrons to the area of the ion source conical slit; figure 3 schematically illustrating a cross-sectional view of an ultra-fine ion polishing system and/or crystal growth according to another embodiment of the present invention; and, figure 4 schematically illustrating a cross-sectional view of a hyperbolical plasma beam source according to another embodiment of the present invention.

SUMMARY OF THE INVENTION

In the field of cathodic arc plasma, it is one of the objects of the present invention to disclose a method of obtaining a high current all-round emission of hot Electrons by a Arc Plasma Round Emitter. The hot electrons emission process is achieved through synergetic co-operation of several physical mechanisms, which comprises, inter alia, following ones: (a ) in Arc Plasma Discharge, ejecting plasma to the space between cathode and anode of the Arc Plasma Emitter of Electrons, wherein said plasma comprises electrons with a temperature of about 1 eV to about 3 eV and ions, particularly copper ions, from retrogradely propagating cathodic spots, which are formed on a surface of a round shaped cold cathode in a vacuum environment; (b) forming a Current Carrier Hall Layer as a result of interaction of said plasma with magnetic field, which force lines pierce an imaginary plane, which is perpendicular to the main axis of symmetry of the both round shaped cathode and anode of said emitter, over normal direction to said plane, and with electric field, which force lines are cross oriented to the said magnetic field force lines and which is obtained by applying substantially before an ignition of said arc plasma discharge voltage to said anode and cathode from external power supply;(c) emitting particles, comprising more 90% of said hot electrons from the total emitted particles, through passages of the said round shaped anode; (d) feeding at least a portion of the electrons towards an exit slit of Ion Source, wherein said slit is formed by poles of magnetic system of said Ion Source to shim magnetic field in the slit space; (e) enabling hottest electrons to penetrate said slit; (f) colliding said electrons in a space between anode and cathode of said Ion Source with molecules or atoms of operational gas selected from a group including noble gas, especially argon, or gas containing carbon atoms, such that operating gas ions are obtained; (g) accelerating said operating gas ions having mainly one positive charge, along rectilinear trajectories, forming a hyperbolic surface, by a means of at least one plasma lens; and,(h) admixing remained portion of said hot electrons to the beam of said operating gas ions in that part of the beam, which is adjacent to said exit slit of the Ion Source, especially on a distance of about 1 mm to about 150 mm from the said exit slit, to substantially neutralize the said ion beam, that is to form a high density plasma beam, where the plasma density is reached extreme value in cross-section of maximum convergence.

The high density plasma may be provided in either a series of pulses, in a stationary manner or any combination thereof.

It is also in the scope of the present invention wherein the method defined above further comprises accommodating a substrate to be treated in a vacuum in a predetermined environment selected from a diluent, solvent, solution, liquefied metal or any other composition in the gas, liquid or solid phase, such as an effective thermal conductivity between said substrate and its surroundings.

The range of focused region preferably ranges between about 2mm to about 40 mm, preferably about 2 mm when the applied voltage is about 500V, such as that hot plasma is provided by applying only ion energy, e.g., about 100 to 500 eV. When the applied voltage is about 100V the focused region would be about 40 mm.

It is also in the scope of the present invention wherein the aforesaid method additionally comprising utilizing the obtained high density plasma, for treating at one or more pre-polished substrates, wherein the Debye radius of said plasma is close to the roughness of said substrates. Preferably yet not exclusively, the Debye radius ranges from about 0.1 μm to about 10 μm.

Another object of the present invention is to provide the method as defined above, especially useful for ultra-polishing one or more substrates. This method comprises steps selected in a non-limiting manner from a. emitting high density plasma towards said substrates; b. charging its peaks with a negative electrical charge; c. bombarding said charged peaks of roughness by said plasma ions; and, d. spattering said peaks to about 0.1% to about 10% of said plasma Debye radius.

Another object of the present invention is to provide the method as defined above, especially useful for crystal growth. This method comprises steps selected in a non- limiting manner from: a. providing operating gas containing carbon atoms as target product and atoms of by-products, in particular, hydrogen atoms; b. obtaining high density plasma with warm or hot electrons (electrons with a temperature of about IeV to about 10 eV); c. providing an orifice which is perpendicular to the main longitudinal axis of the plasma cone; wherein the diameter of said orifice is higher than focus of the hyperbolic carbon beam and further wherein the diameter of said orifice is lower than the diameter of the maximum converge of the hydrogen beam such as the hydrogen ions are not penetrating through said orifice; and, d. accumulating of said carbon ion with energy of about 100 eV to form a homogeneous tetrahedral carbons bonds.

The carbon operating gas are selected in a non-limiting manner from a group comprising ethanol, methanol, propanol, butanol, methane, ethane, propane, butane, acetone, low molecular ketones, low molecular aldehydes, kerosene or any other either oxygen or chlorine free carbohydrates.

The accelerated ion voltage of the carbon ions is preferably varied along the process from about 90 to about 150 V.

It is also in the scope of the present invention wherein the penetration of the hydrogen ions throughout the orifice is prevented. Hence, the method comprising converting said hydrogen ions to H₂ gas which is further evacuated by applying effective vacuum.

It is also in the scope of the present invention to disclose a method of obtaining a high current electrons arc plasma rounded emitter of hot electrons, having high temperature of about 10 eV to about 15 eV comprising: a. ejecting plasma from retrogradely motioned cathodic spots originated from a surface of a cold cathode in a vacuum, such that a Current Carrier Hall Layer parallel to magnetic field is obtained; and such that a plasma comprising electrons, having temperature of IeV to about 3 eV electrons, and ions, particularly copper ions, are emitted to the space between said cathode and said anode; and, b. emitting particles comprising mote than about 90% of said hot electrons from the total emitted particles, through the said passages of the said anode.

It is also in the scope of the present invention wherein the methods defined above comprising holding the substrate to be treated by a means of a cooled holder, which is either non-conductive or conductive under floating potential substrate.

Another object of the present invention is to disclose a novel source of dense plasma, is especially adapted to provide an ultra fine polishing an object, particularly a gemstone (e.g., a diamond) and/or to grow 3D crystals of predetermined characteristics. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description is provided, alongside all chapters of the present invention, so as to enable any person skilled in the art to make use of said invention and sets forth the best modes contemplated by the inventor of carrying out this invention. Various modifications, however, will remain apparent to those skilled in the art, since the generic principles of the present invention have been defined in the art of a cathodic arc plasma, to provide a system and a method of obtaining a high current source of electrons useful for simultaneous treating of one or more mechanically pre- polished substrates and for a 3D crystal growth.

The term "about" denotes hereinafter to ±20% difference.

The emitter of electrons consists inter alia of a cold cathode, screens, magnetic system and anode. The emitter provides electrons for both the ion source and to the hyperbolic shaped ion beam, produced by the said ion source, to neutralize space charge of the said ion beam. As result of such neutralization the ion beam is converted to Plasma Beam. The higher mobility of electrons, in comparison with mobility of ions, prevents development of electric field in the plasma. A very strong restriction of electrons' mobility inside the said ion source is reached in a magnetic field which direction is perpendicular to the accelerating electrical field. The magnetic field magnitude is adjusted in such a way that the field magnetizes the electrons only, so as ions easily leave their acceleration zone.

It is acknowledged in this respect that at least a portion of the anodes are perpendicular, parallel or tilted, (e.g., said tilt is in any predetermined angle or rotation) in respect to cathode. At least a portion of the anodes, especially those located at the very peripheral end of the anode structure, are linear members, curved members, polygonal members or any combination thereof.

A theoretical introduction is hereto provided in a non-limiting manner. Thus, the explanations and equations are given hereinafter solely as an example, provided an illustrating means for understanding preferred embodiments of the present invention: A constitutive equation for an electric field in the cold rarefied plasma is provided by an analysis of driving of electrons of plasma in a hydrodynamic approximation:

E + [v_e x B] = 0 (1) wherein E denotes an electric field in plasma, v_e denotes a drift velocity of electrons in crossed fields.

Ion source with Anode layer are a kind of design concept commonly known as a cold-cathode ion source which comprises a slit or channel, in which electrons drift over a closed loop electron drift ion-emitting channel or slit and through which emission of ions happens. This ion source design comprises a magnetic-conductive housing which serves simultaneously as a cold cathode. An ion emitting channel and anode are arranged in the magnetic-conductive housing being symmetrical with respect to an ion-emitting slit. The channel is a continuous magnetic gap, configured in a closed loop channel, design for propagation of an electron drift current developed by crossed electric and magnetic fields in the channel. A DC voltage applied to the anode develops an electric field that accelerates ions away from the channel toward the substrate. This electric field in plasma appears only in the electron drift field, not all over discharge space. The magnetic force lines become equipotentials in plasma with a good conductivity. It allows considering them and the electrons curl on them as singular electron-magnetic electrodes (EME). Unlike usual electrodes, however, EME are transparent and ensure a quasi-neutrality of ionic streams. The self-contained drift of electrons is carried out along a slit in a crossed electrical and magnetic fields. Thus, electrons make an azimuth drift and move to the anode in a diffusive mode. During said drift, electrons collide with atoms, e.g., argon, and move towards the anode. A fraction of the collisions result with ionization of atoms of the operational gas. Ions are accelerated in a direction of a slit. As plasma possesses a high electrical conductance along a magnetic field force lines become equi-potential and the potential gradient is guided to become perpendicular in respect to the magnetic force lines. The configuration of electric fields in plasma may coincide with an electrostatic lens in electronic or ionic guns and can be used for focusing ions. Focusing ions from aforesaid source is especially useful as it is focused towards an aperture (e.g., an orifice of about 10 mm), providing an effective separation of ion beam of carbon from contaminated protons (i.e., ion extraction).

Such a mechanism may be disclosed in mathematical equations as such as defined hereinafter. Having passed the slit, ions acquire a perpendicular component of velocity, which depends only on ion mass M:

wherein ΦA denotes an intersected magnetic flux, and RA denotes a radius of an entrance slit. An example is hereto provided; for ΦA=5.98- 10^"5 Wb, (average m βeU _d magnetic field B_n=0.016 T), v_θ = 4.55 - 10 ³ — , and because v = J - , then s V M an angle under which the ion goes out of a slot is equal:

At a voltage on the ion Source U_d equals 300 V and diameter of slot RA equals 5 cm, for carbon θ equal 4° and for atoms of hydrogen θ equals 14°.

In a distance away from said slit the source vertex of the cone R_s equals to about 10 cm wherein carbon C⁺ and hydrogen H⁺ from comprising a vertex of re =2.2 mm, Γ_H =7.6 mm, respectively.

It is according to another embodiment of the present invention wherein the pressure at the working chamber is range from about 10"5 to about 10"2 Torr; a typical current of about 1OA may be accordingly used. High open-circuit potential, e.g., up to 600 V may be applied, such as a cross magnetic field (e.g., about 100 to about 170 G) at the cathode-anode spacing of about 6 to 10 mm is provided.

It is acknowledged that the vacuum-arc discharge current may be concentrated at a surface of cathode. Arc discharge forms so-called 'cathodic spots', that are locations of extremely high current density, e.g., about 10^2 A/m^. The high current density is potentially associated with high area power density, e.g., about order 10^3 W/m2, which in turn provides conditions for localized phase transformation from solid (the cathode material) to fully ionized plasma. Positive ions characterized by an energy W₁-IOeV and temperature T_e~\÷3eVmy be obtained.

Reference is made now to figure 1, schematically presenting a Hall Current Layer model as was suggested in the literature, See for example Meunieret al., "Bouncing Expension of the Arc-Cathode Plasma in Vacuum Along the Transverse Applied B Field", IEEE Trans.on Plasma ScL, 11 (3), pp. 165-168 (1983). An electric field E is excited and maintained at the near-the-boundary layer, which keeps the fast ions Ej_. An electron drift velocity in the near-the-boundary layer is

V_j1. = E_x/ B , wherein B is a magnetic field intensity in the near-the-boundary layer.

The arc electron beam current I₀ is provided by the flux of electrons drifting along the near-boundary layer, which is called the Hall Current Layer. Cross section of the near-the-boundary layer by plane, which is oriented normally to the magnetic field force lines, has a shape, which is described by the equation of a cardioid, in

following form r = r₀ sin² — :

wherein K_r denotes a coefficient, which accounts the ion multiple reflection by the near-the-boundary layer, Ki= Ii / Ie ~ 0.1, and M, Z, Wi denote accordingly to the mass, charge and average energy of the fast ions.

The arc discharge can exist if the anode is located on the way of the drift of electrons, i.e., is intersected with the cardioid. The farther from the cathodic spot is anode, the higher is voltage at the current layer since this voltage increases with the angular coordinate α :

c_{/ =}i._sin2 ^« ₍₅₎

^■ e 2

The discharge gap voltage is increasing by approximately the same value. If the near- anode potential drop is neglected, the total voltage at the discharge space in the presence of the transverse magnetic field may be as follows:

U_AK = U_arc + U (6)

wherein U_arc - denotes the discharge space value with no transverse magnetic field.

Hence, substantial elevation of voltage on a discharge space is increasing the temperature of electrons. With the higher voltage at the discharge space U _Aκ » U_arc , maintenance of a stable arc discharge can be a complicated task.

Reference is made now to figure 2. Ions reaching the boundary layer are electrostatically reflected, while electrons maintain their drift along the Hall Current Layer, may penetrate through a slit in the anode of the emitter of electrons to the area of the ion source conical slit.

Existence of a stable Current Carrier Hall Layer and passage of the arc current through a transversal magnetic field are possible only at the certain shape of a magnetic field and at application of anode with a certain geometrical features.

An innovative design is offered with the purpose to optimize the shape of the Current Carrier Hall Layer with an account for motion of the cathodic spots via optimization of the magnetic field configuration.

It is according to yet another embodiment of the present invention wherein a toroidal-shaped magnetic field, such a one produced by a permanent magnet poles located at both sides of the cathode, is utilized to maintain the aforesaid cathodic spots on a predetermined location on the cathode, avoiding hence loss of plasma due to its escape along the magnetic field.

Potentially, discoid metal screens under a floating potential are placed near the annular metal cathode, i.e., one discoid screen at each side of the cathode. The discoid screens may protect non-work surfaces of the annular cathode from obtaining infiltration or intrusion on them. This special arrangement is yielded with an increase stability of vacuum arc discharge.

The term 'plasma' refers hereinafter to any electrically conducting medium comprising equal numbers of positively and negatively charged particles, produced when the atoms in a gas become ionized.

The term 'ionization' refers hereinafter to any process by which electrically neutral atoms or molecules are converted to electrically charged atoms or molecules (ions) by the removal or addition of negatively charged electrons.

The term 'cathodic arc plasma' refers hereinafter to ejection of plasma flux provided from a cathodic spot. The plasma flux may consists of following components: a flux of "warm" electrons (e.g., electrons with a temperature Te = 2÷3 eV); a flux of metal ions with an energy Wi which ranges from about 50 to about 100 eV, wherein the ions mass flow is about 50 to 98% of a total mass flow in such ejected flux of plasma and a flux of neutral particles. The term "ion sources with anode layer", relates to any design methodology of a cold-cathode ion sources, where electrons are drifting over closed loop in ion- emitting slit (or channel).

This ion source design preferably comprises a magneto-conductive housing which is used as a cold cathode source of electrons. An ion emitting channel and anode are symmetrically embedded (relatively to the ion-emitting slit) into magneto-conductive housing. The channel is a continuous magnetic gap, which is configured as a closed loop contour or racetrack, to provide a propagation of an electron drift current formed by crossed electric and magnetic fields in the channel. An electron drift velocity, current density and rotation radius are a functions of electric and magnetic field intensities within the channel and are defined by following equations: V_dri_ft = E/B, Ie = neqvdri_tt and Γ_L = mve/qB.

A magnetic field gradient retains electrons within the channel due to a mirror magnetic configuration of a pole, wherein electrons are used for repeated ionization of the operational gas atoms. A DC voltage, which is applied to the anode, forms an electric field that accelerates ions in a direction from the channel toward the substrate.

The dimensions of the ion source may range from few centimeters to meters, wherein emission slits of various shapes can be utilized. Preferably the ion source is designed in the manner that a plurality of n slits are provided wherein said slits are suitable for conical ion beams creation, further wherein n is any integer number higher or equal 1. Said conical shape is preferably yet not exclusively related a truncated conical shape or any similar convergenced shape. An available working range of pressure is typically from about 10^"' to 10 ^"" Ton-.

Debye radius of plasma r_D=(T_eεo/ne²)^1/2 Debye radius (Debye length) of screening ion sputtering of materials surface by ions with an energy, which is in excess of sputtering threshold, which is about 7 to about 15 eV. Ions energy value; W*i, that corresponds to maximal energetic efficiency of material sputtering process, is described by following formula:

W* , = 515a²ZiZ_a(mi + m_a)/m_a (6)

If ions of argon are used as a bombarding ions

and diamond (carbon atoms) is used as a target material (Z_a=6, m_a= Mc =12), then W*,=5.2-10^"17 J = 320 eV.

The term 'ion polishing¹ denotes any method and means adapted to polishing by ion sputtering process.

The term 'hot electrons' denotes to electrons having temperature equivalent (e.g., as function of Boltzman constant) to 10 eV to 15 eV.

The term 'ultra-polishing process' denotes polishing process designed to reduce the roughness of (mechanically-) pre-polished substrate with a roughness above Ra equals 100 nm down to roughness values below 100 nm.

Reference is made now to figure 3, schematically illustrating a cross-sectional view of an ultra-fine ion polishing system and/or crystal growth according to one embodiment of the present invention.

This system comprises in a non-limiting manner operational modules selected from the following: a working vacuum chamber 3000; vacuum pumping system 4000 which is communicated to chamber 3000 to provide necessary vacuum environment in it. Hyperbolical plasma beam source 1000 is attached hermetically, i.e., vacuum tight to chamber 3000.

Hyperbolical plasma beam source 1000 comprises inter alia an ion source 100 and a vacuum arc plasma emitter of hot electrons 200 being a plasma emitter of electrons. Plasma emitter 200 is connected inter alia to power supply 2200 and 2300. Operational gas feeding system 5000 is connected to the hyperbolical plasma beam source 1000. Samples holder 3100 is connected to power supply 2400. Masking device 3200 may be installed inside the work vacuum chamber 3000.

Reference is made now to Figure 4 schematically illustrating a cross-sectional view of the proposed hyperbolical plasma beam source. Hyperbolical plasma beam source 1000 comprises inter alia ion source 100 and plasma emitter of electrons 200. Ion source 100 comprises elements selected in a non-limiting manner from an earthed steel housing 110, gas discharge chamber 140, magnetic field generating means 130, anode, e.g., hollow anode, 112, electric feed through 113, e.g., 2 pieces.

Housing 110 houses a magnetic field generating means 130. A permanent magnet or electromagnetic coil may serves as such magnetic field generating means. The coaxially arranged magnetic field generating means 130 is fixed to the inner surface of housing 110 so as to obtain a conical magnetic field within the conical slit of the ion source 100.

A positively biased anode 112 is allocated on a short distance from the conical magnetic slit between the housing 1 10 and inner ring 114. The conical slit, i.e., a magnetic gap, allows the generated ion beam to exit the ion source. Anode 112 is connected to the power supply 2100 through a pair of electrical feed troughs 113. Feed troughs 113 may be utilized also for cooling the anode 112 by liquid or gaseous coolant, e.g., water, ozone-friendly Freon, etc. The cooling may also be performed by any other piping system, conducting the coolant to the anode.

An operational gas is fed by feeding system 5000 to gas discharge chamber 140 of the ion source 100 through the high-speed gas pulse valve 121, by feeding pipe 120. Annular cavity 115 with circular exit slit is used for uniform feeding of an operative gas to gas discharge chamber 140.

Plasma emitter of electrons 200 is allocated at the central part of the plasma source design. Anode 220, which has a shape of truncated cone, is preferably made of nonmagnetic metal.

Conical surface of the cone is notched over its generating line to form pins, which are needed to form magnetic field of necessary configuration, the field is appeared at conduction a part of discharge current through the pins, at the area of the hot electrons exit in direction towards circular slit of ion source 100.

Anode 220 is connected to power supply 2200 through electric feed through 222. Feed through 222 may be utilized also as an inlet and an outlet of coolant, e.g., water, Freon, etc. The cooling may also be performed by any other piping system, conducting the coolant to the anode. Cathode 210 is preferably made of nonmagnetic material. Cathode 210 is placed, together with any system of vacuum arc initiation 250. Circular cathode 210 is connected to power supply 2200 through electrical feed through 211. Feed through 211 may be used also for coolant supply to inner cavity of circular cathode 210. The cooling may also be performed by any other piping system, conducting the coolant to the cathode. Magnetic system 240 consists of magnetic pole 241, magnetic pole 243 and a permanent magnet 242.

The invention pertains to the use of enhanced plasma emitter of electrons to increase the supply of electrons in a hyperfine ion polish system including as a basic element the ion source of noble gases with conical discharge (yield) of an ion stream in a combination to the cathodic arc plasma emitter of electrons.

The purpose is obtaining dense plasma with the performances ensuring a possibility to dilate a gamut of surface smoothness (effective smoothing of irregularities on a surface of a target) and a velocity of hyperfine polishing.

The use of plasma emitter of electrons allows to increase a discharge current and flux density of ions from a source at smaller voltages on discharge and a smaller energy of the accelerated ions; receive more dense, than at prototypes, a plasma stream and due to it to increase a velocity and quality of polishing.

Use of the cathodic arc emitter allows gas efficiency factor to increase. Allowing for ion source operation at lower gas pressure also increases the range of ion source applications and improving operation at all pressures.

The use of enhanced cathodic arc plasma emitter of electrons reduces the erosion of component parts in the ion source avoiding danger of contamination of a target surface by the erosion yields.

The cathodic arc plasma emitter section of the ion source represents the cabinet of a vacuum arc disposed near to outlet of the ion source and consists of a cold cathode, screens and the anode, and is simultaneously electrons source for discharge that provides an addition source of electrons for the ion source and for adding electrons in a stream of plasma to provide electron flow to the ion beam to neutralize a space charge.

In usual two-electrode system of extraction of ions from plasma (Peirce system) the beam current is limited by a characteristic space charge. Therefore greater currents of ions are reached or at the significant voltage of extraction, or at a major emission surface.

Removal of restrictions on a ions space charge probably on the basis of principles plasmaoptics which considers processes of acceleration of bundles especially in a quasineutral medium [I].

Embodying of an electric field in plasma is hindered by greater mobility of electrons. Sharp restriction of mobility of electrons is reached in a magnetic field which direction is perpendicular to accelerating electrical. Magnitude of a magnetic field should be sufficient for magnetization only an electronic component that ions easily abandoned a band of dispersal.

The equation for an electric field in the cold rarefied plasma - the constitutive equation - follows from the analysis of driving of electrons of plasma in a hydrodynamic approximation E + [v_c x S] = 0 , (l)

where E - an electric field in plasma; v_e - the drift velocity of electrons in crossed E₁B fields.

The plasmaoptical system of ion extraction allowed to form the ion beams, where the current is independent from extraction voltage, is analyzed. The offered source of ion beam will be used for those purposes, which require the large currents of ions with low energy.

Anode Layer Sources are a design methodology commonly known as a cold-cathode ion source with a closed loop electron drift ion-emitting channel or slit. This ion source design comprises a magneto-conductive housing engaged as a cold cathode electron source. An ion emitting channel and anode are arranged in the magneto conductive housing symmetrically with respect to the ion-emitting slit. The channel is a continuous magnetic gap, configured in a closed loop channel, for propagation of an electron drift current developed by crossed electric and magnetic fields in the channel.

A DC voltage applied to the anode develops an electric field that accelerates ions away from the channel toward the substrate. The electric field in plasma appears only in the electron drift field, instead of in all discharge spaces.

In plasma with good conductivity the magnetic force lines, to truth to kT_e/e, become equipotential. It allows to consider them together with electrons curl on them as singular «electron-magnetic electrodes (EME)». But unlike usual electrodes they are transparent and ensure a quasi -neutrality of ionic streams.

Along a slot the self contained drift of electrons in the crossed electrical and magnetic fields is carried out. During a drift electrons interfere with atoms, for example, an argon and due to collisions move to the anode. Thus electrons make an azimuth drift and move to the anode in a diffusive condition. The part of collisions results in ionizations of atoms of gas. Ions are accelerated in a direction of a slot.

Example 1

In the experiment the Plasma source system was used with two sources of plasma. The system was working inside vacuum chamber. The chamber was evacuated until getting pressure of 7-10-^ Torr. The temperature of the chamber walls at the beginning was 293⁰K.

Diamond like Carbon film was grown in the process of the experiment. For training of basement Argon source was used. We took chemically free acetylene for film growing. The pressure inside chamber rose until 3-10^~5 Torr while acetylene was injected. The process of growing was divided for two stages. The first stage lasted 5 minutes. The Plasma source was fed with current of 3A during first stage. The plasma was emitted with pulses whose length is 20 ms. and frequency of 10 Hertz. The pressure in the cut-off period (between pulses) between pulses changed from

7-10"5 Torr. The voltage was 1,000V. At the second stage which lasted 20 minutes the system was in state of DLC covering. System was fed by current of 2A with frequency of 1 Hertz. The film was placed on the copper basis. The temperature had been controlled not to exceed 423⁰K. The voltage of the Plasma source was 100V. The Bias voltage was floating. We got plate with thickness of 0.001 mm and size of 100 square mm by the end of experiment. It was DLC. The hardness of the sample was 9500 HV

Example 2

The Plasma source system was used in the experiment with one source. In the experiment we polished diamond using plasma. In the experiment we used vacuum system with cubic chamber. The chamber was evacuated until we get vacuum of 7-10^~5 Torr. In the experiment diamond was polished using plasma.

Diamond weighting 1.46 carat was taken for the experiment. The gas we used in the process of polish was Argon. The temperature of the chamber walls has been 294⁰K. The experiment was preformed in two stages. Diamond's "Table" face has been polished using plasma. In order to keep other facets of diamond from damage the plasma reached diamond through mask. The mask was in form of 8-side polygon.

In the first stage diamond was prepared for polish. Preparation has been done during 10 minutes until we get charge of 1 coulomb per square cm. The system was fed by current of 2 A. The discharge voltage was 500V DC.

The second stage lasted 5 minutes. We polished the diamond by Argon. The pressure changed during the working impulse. The pressure during working impulse rose up to 3-10-4 Torr. The current was 2A. The discharge voltage was 300V.

The temperature had been controlled during all experiment in order to avoid diamond damage.

We note that weight of polished diamond remained 1.46 karat. Precision of polish attained due to film thickness.

The as-polished surface was characterized by the TALYSURF™ Phase Shift Laser Interferometer which checks in 3D the quality of surface. Its precision let us know the high quality.

Example 3

For the experiment we used described source of plasma. The system was mounted on the vacuum chamber. A quartz lens was placed on the basement in the chamber.

The chamber was evacuated to pressure of 7-10"5 Torr In the process of the experiment we covered Lens by Diamond like Carbon Film. The lens is used in optical device, which is used for micro-chip production. In the system we used two types of operational gas, namely acetylene and argon. Argon was used for training of the sample. A voltage on the plasma source was 500V DC. Training of the lens was performed during 10 minutes with use of 20 ms duration pulses at a frequency of 10 pulses per second.

The Pressure in the chamber rose until 3-10"4 Torr during working pulse (while valve was opened and argon gets in). The size of the worked lens was 10 mm diameter and 2 mm thickness. After heating we placed DLC on the sample. The thickness of the film is 1000 A. The covering process lasted 20 sec. with pulses of 20 ms, frequency of 5 Hz, the voltage on plasma source was 100V. The current was IA. The source used for DLC generation was acetylene. The acetylene got inside the chamber through valve. The pressure inside the chamber changed from the 7-10-^ Torr, during the working impulse. As a result of film covering we protected the lens from etching and made it suitable for using in chemically active areas. The lens was checked by interferometer TalySurf. The check reveals high quality of the surface.

Claims

1. In a calhodic arc plasma, a method of obtaining a high current emission of hot electrons by an Arc Plasma Emitter, comprising: a. in arc plasma discharge, ejecting plasma to the space between cathode and anode of said emitter, wherein said plasma comprising electrons having temperature of about 1 eV to about 3 eV, and ions, especially copper ions, from retrogradely propagating cathodic spots, which are formed on a surface of a round shaped cold cathode in a vacuum environment; b. forming a Current Carrier Hall Layer as a result of interaction of said plasma with magnetic field, which force lines pierce an imaginary plane, which is perpendicular to the main axis of symmetry of the both round shaped cathode and anode of said emitter, over normal direction to said plane, and with electric field, which force lines are cross oriented to the said magnetic field force lines and which is obtained by applying substantially before an ignition of said arc plasma discharge voltage to said anode and cathode from external power supply; c. emitting particles, comprising more 90% of said hot electrons from the total emitted particles, through passages of the said round shaped anode; d. feeding at least a portion of the electrons towards an exit slit of Ion Source, wherein said slit is formed by poles of magnetic system of said Ion Source to shim magnetic field in the slit space; e. enabling hottest electrons to penetrate said slit; f. colliding said electrons in a space between anode and cathode of said Ion Source with molecules or atoms of operational gas selected from a group including noble gas, especially argon, or gas containing carbon atoms, such that operating gas ions are obtained; g. accelerating said operating gas ions having mainly one positive charge, along rectilinear trajectories, forming a hyperbolic surface, by a means of at least one plasma lens; and, h. admixing remained portion of said hot electrons to the beam of said operating gas ions in that part of the beam, which is adjacent to said exit slit of the Ion Source, especially on a distance of about 1 mm to about 150 mm from the said exit slit, to substantially neutralize the said ion beam, that is to form a high density plasma beam, where the plasma density is reached extreme value in cross-section of maximum convergence.

2. The method according to claim 1, wherein said high density plasma is provided in either a pulse mode and/or in uninterrupted mode.

3. The method according to claim 1, wherein said cross-section of maximum convergence has substantially round shape with diameter of about 2 to about 40 mm, and wherein ions of the said high density plasma are accelerated to energy of about 100 to about 500 eV, respectively.

4. The method according to claim 1 useful for utilizing said high density plasma for ultra-fine polishing of preliminary polished substrates.

5. The method according to claim 4, wherein the Debye radius of the said plasma in the plain of maximum convergence of the said plasma beam ranges between about 0.1 μm to about 10 μm.

6. A method of ultra-polishing one or more substrates according to claim 5, comprising: a. emitting said high density plasma provided by interaction of noble gas, especially argon as the operating gas, towards said substrates; b. charging substrates peaks of roughness with negative electrical charge of said hot electrons from said high density plasma; c. bombarding said charged peaks by positive ions of said high density plasma; such that peaks are spattered to resulting height of about 0.1% to about 10% of said plasma Debye radius.

7. The method according to claim 1 especially adapted for crystal growth, comprising: a. providing operating gas containing carbon atoms as target product and atoms of by-products, in particular, hydrogen atoms; b. obtaining high density plasma wherein the electrons have a temperature in the range of about IeV to about 10 eV, especially of about 5 eV to about 10 eV; c. providing an orifice which is perpendicular to the main axis of symmetry of the plasma beam; wherein the diameter of said orifice is higher than critical cross-section diameter and further wherein the diameter of said orifice is lower than the diameter of the minimum converge of the hydrogen plasma beam such as the hydrogen ions are not penetrating through said orifice: and, d. accumulating said carbon ions wherein the voltage applied on the accelerated carbon ions is in the range of about 90V to about 150 V to form a solid homogeneous tetrahedral carbons bonds.

8. The method according to any of claims 7 and 1, wherein said gas containing carbon atoms is selected from a group including ethanol, methanol, propanol, butanol, methane, ethane, propane, butane, acetone, low molecular ketones, low molecular aldehydes, kerosene or any other either oxygen or chlorine free carbohydrates.

9. The method according to claim 7, wherein the penetration of the hydrogen ions throughout the orifice is prevented, comprising converting said hydrogen ions to H₂ gas which is further evacuated by applying effective vacuum.

10. A method of obtaining a high current electrons arc plasma rounded emitter of hot electrons, having high temperature of about 10 eV to about 15 eV comprising: a. ejecting plasma from retrogradely motioned cathodic spots originated from a surface of a cold cathode in a vacuum, such that a Current Carrier Hall Layer parallel to magnetic field is obtained; and such that a plasma comprising electrons, having temperature of IeV to about 3 eV electrons, and ions, particularly copper ions, are emitted to the space between said cathode and said anode; and, b. emitting particles comprising mote than about 90% of said hot electrons from the total emitted particles, through the said passages of the said anode.

1. A system useful for obtaining electrons, having temperature of about 1 to 15 eV, comprising plasma beam source 1000 comprises inter alia ion source 100 and plasma emitter of electrons 200; said ion source 100 comprises elements selected from an grounded steel housing 110, gas discharge chamber 140, magnetic field generating means 130, anode, e.g., hollow anode, 112, electric feed through 113, e.g., 2 pieces; housing 110 houses a magnetic field generating means 130; a permanent magnet or electromagnetic coil may serves as such magnetic field generating means; the coaxially arranged magnetic field generating means 130 is fixed to the inner surface of housing 110 so as to obtain a magnetic field within the slit of the ion source 100; a positively biased anode 112 is allocated on a short distance from the magnetic slit between the housing 110 and inner ring 114; slit, i.e., a magnetic gap, allows the generated ion beam to exit the ion source;; an operational gas is fed by feeding system 5000 to gas discharge chamber 140 of the ion source 100 through the highspeed gas pulse valve 121, by feeding pipe 120; annular cavity 1 15 with circular exit slit is used for uniform feeding of an operative gas to gas discharge chamber 140; said plasma emitter of electrons 200 is allocated at the central part of the plasma source design; anode 220 is connected to power supply 2200 through electric feed through 222 ; cathode 210 is accommodated, together with a system of vacuum arc initiation 250 cathode 210 is connected to power supply 2200 through electrical feed through 211,; magnetic system 240 consists of magnetic pole 241, magnetic pole 243 and a permanent magnet 242or electromagnetic coil which may serves as such magnetic field generating means; said plasma beam source 1000 hermetically attached to a working vacuum chamber 3000 with a plurality of samples holder 3100; vacuum pumping system 4000 in communication with chamber 3000; wherein said plasma beam source 1000 is adapted for ejecting ion cathode plasma from retrogradely motioned cathodic spots originated from a surface of a cold cathode in a vacuum, such that a Current Carrier Hall Layer parallel to magnetic field is obtained; and such that said cathode plasma comprising electrons, having temperature of about IeV to about 3 eV electrons, and ions, particularly copper ions, emitted to the space between said cathode and said anode.

12. The system according to claim 11, useful for feeding at least a portion of the same towards a slit an exit slit of ion source comprising a shimming magnetic field; for forcing hottest electrons to penetrate said slit; for ionizing molecules of atoms of operational gas, provided from an operational gas feeding system 5000; for accelerating said ions of said operating gas with mainly one positive charge, along an ion hyperbolic surface, by a means of at least one plasma lens; and for providing said high density plasma beam to remain in focused in the manner of neutralizing the space charge by emitting hot electrons originated from a location adjacent to said slit, especially from about lmm to about 150 mm and directing the same towards the focused region of said plasma beam.

14. The system according to claim 11, especially useful for crystal growth, additionally comprising a masking device 3200, being installed inside the work vacuum chamber 3000.

15. The system according to claim 11, adapted for ultra polishing an object, especially a gemstone.

16. The system according to claim 11, especially useful for emitting particles, comprising more than 90% of said hot electrons from the total emitted particles;

17. The system according to claim 11 or any of its dependant claims, wherein said system is cooled.

18. A high current arc plasma emitter of hot electrons 200, having high temperature of about 10 eV to about 15 eV, comprising: a. anode 220 having passages for exit of said electrons; b. at least one screen; c. cold cathode 210 being accommodated, together with a system of vacuum arc initiation 250; and, d. magnetic system 240 adapted for creating magnetic field around said cathode consists of magnetic pole 241, magnetic pole 243 and a permanent magnet 242.