Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/34—Sputtering
  • C23C14/35—Sputtering by application of a magnetic field, e.g. magnetron sputtering
  • C23C14/354—Introduction of auxiliary energy into the plasma
  • C23C14/358—Inductive energy
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
  • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
  • C23C14/54—Controlling or regulating the coating process
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
  • H01J37/3402—Gas-filled discharge tubes operating with cathodic sputtering using supplementary magnetic fields
  • H01J37/3405—Magnetron sputtering
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
  • H01J37/3411—Constructional aspects of the reactor
  • H01J37/3444—Associated circuits
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/34—Gas-filled discharge tubes operating with cathodic sputtering
  • H01J37/3464—Operating strategies
  • H01J37/3467—Pulsed operation, e.g. HIPIMS

Definitions

• the present invention relates generally to the deposition on a substrate of a material vaporized by sputtering in a magnetron. It relates to a new method of depositing at least one material on a substrate by magnetron sputtering in pulsed regime, as well as a new pulse electrical supply for magnetron, and a magnetron equipped with said pulse supply.
• the technique of depositing a material on a substrate by magnetron sputtering generally consists in bombarding a target, which forms the cathode of a magnetron reactor and which is produced in the material to be deposited. , with ions from an electrical discharge (plasma).
• This bombing ionic causes the target to sputter in the form of a "vapor" of atoms or molecules which deposit, in the form of a thin layer, on the substrate placed near the magnetron target, the substrate possibly being fixed or mobile.
• the gas intended to form the plasma is an inert gas, for example argon.
• a gas is used, generally diluted in an inert gas, to generate a compound which may or may not be electrically conductive; with a titanium target cathode, for example, a mixture of argon and nitrogen is used as reactive gas, which results in the formation of an electrically conductive titanium nitride (TiN) compound, or a mixture of argon and oxygen, which results in the formation of a titanium dioxide compound (Ti0 2 ) which is an electrical insulator.
• TiN electrically conductive titanium nitride
• Ti0 2 titanium dioxide compound
• the atoms are ionized essentially by collisions with the electrons produced in the electric discharge.
• the magnetron sputtering methods are implemented at low pressure (typically between 0.1 Pa and a few Pa). As a result, the ions undergo little or no collisions during their path towards the target cathode, which increases the effectiveness of the sputtering. Also, this low pressure makes it possible to facilitate the transport of pulverized material to the substrate, by reducing the collisions of the atoms or molecules pulverized, and therefore reducing the importance of the processes of deflection and / or loss of kinetic energy. particles (atoms or molecules) sprayed.
• the aforementioned technique of depositing material on a substrate by magnetron sputtering is particularly suitable for depositing, essentially in thin layers, a large variety of materials in very varied fields of application such as microelectronics ( metallic interconnection and dielectric deposits for MOSFET structures), optoelectronics (manufacture of piezoelectric substrates), mechanics or connectors (anti-wear, anti-corrosion coating deposits, etc.), the glass industry (functional layers).
• the materials deposited can be metallic materials or electrically conductive compounds, insulating ceramics such as nitrides, oxides, carbides, oxynitrides, etc.
• magnetron sputtering presents the advantage of being more directional, due to the existence of an emission lobe, more or less open, perpendicular to the target cathode, with ejection speeds of the sprayed particles which can advantageously be greater.
• the electrical discharges in the plasma were carried out in steady state by applying a continuous voltage to the cathode or by radio frequency (RF) excitation of the gas. .
• RF radio frequency
• the limitations of the magnetron sputtering technique in steady state are linked to a generally insufficient quality of the deposited layers, particularly in that which relates to porosity, and to the difficulty of obtaining homogeneous deposits on substrates having a deposition surface with complex geometry, and at deposition rates which remain relatively low (typically of the order of ⁇ m / h). More particularly, with regard to the quality of the layers deposited, there is often observed in steady state (DC or RF) the untimely formation of electric arcs, which cause the ejection of material from the target in the form of droplets, which droplets are deposited on the substrate, detrimentally creating defects in the coating.
• the duration of the "On” pulse must be limited (adapted) to limit the surface charge due to the poisoning of the target at the origin of the electric arcs, and that during the "Off” pulse, the surface electrical charge is neutralized. More particularly, it is specified that the most effective suppression of electric arcs is observed when the duration of the pulses "Off” approaches or is equal to the duration of the pulses "On". In the exemplary embodiment given (FIG. 12), the duration of the “Off” pulses represents approximately 10% of the total cycle, and is equal to 5 ⁇ s, the duration of the “On” pulses being equal to 45 ⁇ s.
• the average current is only slightly lower (by 10%) than the pulse current.
• the present invention aims to improve the known methods of depositing a material by magnetron sputtering in pulsed regime, by proposing a new solution which makes it possible in particular to overcome the aforementioned drawbacks, while allowing ionization effective steam spray.
• the invention aims to propose a method of depositing a material by magnetron sputtering in pulsed regime, which makes it possible to generate electric discharges, preferably of high power, with good stability and good reproducibility over time, while reducing the risk of arcing, and reducing the risk of redeposition on the cathode of the sprayed material.
• Summary of the invention The above-mentioned objectives are achieved by the process of claim 1. This process is known in that at least one material is deposited on a substrate in a magnetron reactor equipped with a magnetron cathode.
• a preionization of said gas is carried out so as to generate current pulses whose decay time, after the main voltage pulse is cut off, is less than 5 ⁇ s, and preferably less than l ⁇ s.
• the power supply used in the international patent application WO02 / 103078 (see Figure 9), implements a circuit comprising inductors (L1, L2) in series with the magnetron cathode and allowing limit discharge currents (page 22, line 2). More particularly, according to the teaching of this publication (page 22, lines 2 and 3), the value of the inductance (L1) must be as high than necessary to produce the preionization current. However, the implementation of this inductance in series (L1) is detrimental for the current pulse. Indeed, it introduces a time constant, which prejudicially increases the cut-off time of the current pulse (that is to say the duration of decay of the current pulse after the cut-off of the current pulse voltage).
• the cut-off time of the current pulse is important and is greater than 10 ⁇ s.
• it is not possible to obtain very short cut-off times for the current pulse it is ie cut-off times less than 5 ⁇ s, and preferably less than l ⁇ s.
• the inventors have been able to demonstrate that it was essential, in order to obtain optimal conditions for the deposition of the sprayed material on the substrate, to generate current pulses with a very short breaking time.
• the preionization of the gas according to the invention before each main voltage pulse results in the creation, in the magnetron reactor, of an initial plasma which advantageously makes it possible to reduce the delay time of the current pulse relative to the main voltage pulse, and make this delay time less fluctuating. Compared to a process without preionization, this generates impulse electrical discharges of higher instantaneous power, and with an average power relatively constant over time. Thus, thanks to the process of the invention, the formation of the current pulse is promoted (stabilized and / or accelerated). This preionization is particularly advantageous in a pulse operating regime with short main voltage pulses, which also advantageously makes it possible to reduce the probability of untimely formation of electric arcs.
• Another role of the preionization is to create in the magnetron, between the cathode and the substrate, a sufficient density of free electrons which promotes the transport towards the substrate of the vapors of ionized material.
• Another important advantage of the process of the invention is the obtaining of a high ionization of the vapors arriving on the substrate. Thanks to preionization, an ionization rate of the vapors arriving on the substrate is obtained which is greater than 10% and preferably greater than 70%. This ionization rate is measured in the vicinity of the substrate by an absorption spectroscopy method of the type described in one or other of the two publications below: S. Konstantinidis, A. Ricard, M. Ganciu, J.-P. Dauchot, M.
• Another advantage of implementing a preionization according to the invention is to provide conditioning of the surface of the substrate (pre deposition, ablation, polarization) which allows the modulation of the properties of the deposited layers (adhesion, structure, uniformity) depending on the applications envisaged.
• This advantage is for example particularly advantageous in the field of microelectronics.
• the preionization of the gas before each main voltage pulse can be obtained in several different ways.
• the preionization of the gas is obtained by applying a preionization voltage to the magnetron cathode.
• This preionization voltage is preferably continuous, but can also be drawn, the main thing being that the preionization of the gas (formation of the initial plasma) is effective before the application of the main voltage pulse for the formation of the main plasma.
• the preionization of the gas is obtained by RF excitation of the gas.
• the preionization of the gas is obtained by microwave excitation of the gas or by any other means making it possible to create a sufficient free charge density in the space between the cathode and the anode .
• this density is preferably greater than 10 8 c ⁇ f 3 and more preferably still greater than 10 9 cm "3.
• the preionization can be ensured by a pulse repetition frequency high enough to form a stable current pulse at each voltage pulse, so as to use the density Residual electronics between two successive pulses
• the main voltage pulses for the formation of the main plasma can be applied to the magnetron cathode in a regime of mono-imupulsion type or in regime of type of multi-pulse, that is to say by being generated by successive trains of at least two close pulses.
• the duration of the main voltage pulses is less than 50 ⁇ s, more particularly less than 20 ⁇ s , and preferably between l ⁇ s and lO ⁇ s. More particularly, the frequency of the pulses (single pulse regime) or of the close pulse trains is less than or equal to
• the invention also has other objects as a new impulse power supply for magnetron reactor referred to in claim 13, as well as a magnetron reactor equipped with this impulse power supply.
• FIG. 1 schematically represents a magnetron reactor equipped with a pulse supply of the invention.
• Figure 2 is an electrical diagram of an exemplary embodiment of a pulse power supply of the invention.
• FIG. 3 schematically represents oscillograms respectively of the voltage (U) measured on the magnetron cathode and of the current (I) passing through the magnetron cathode, in an operating regime of the single-impulse type.
• Figures 4 to 17 are real oscillograms of the control signal (S), the voltage (U) and the current (I) above, obtained by screenshot of an oscilloscope under different operating conditions described in detail later.
• Figure 18 shows schematically another alternative embodiment of a magnetron reactor of the invention, with RF loop for preionization. Detailed description of the invention
• FIG. 1 the block diagram of a magnetron reactor 1 equipped with a pulse electrical supply 2 which is according to the invention.
• the magnetron reactor 1 is known per se. Its structure and general functioning are briefly recalled.
• the magnetron reactor 1 essentially comprises, and in a manner known per se, a deposition chamber 10 inside which is mounted a cathode CM, hereinafter called the magnetron cathode.
• CM cathode
• the enclosure 10 is further equipped with an intake system 12 for the introduction of a gas or gas mixture, which once ionized will form a plasma.
• the magnetron cathode consists of a sample of the material which it is desired to deposit in the form of thin layers on the substrate 11a.
• the power supply 2 allows in operation to apply to the magnetron cathode CM a negative voltage which generates within the gas of the deposition chamber 10 of the electric discharges resulting in the formation of a discharge current passing through the magnetron cathode CM, and by a strong ionization of the gas (formation of a main plasma).
• the ions of this main plasma bombard the surface (target) of the magnetron CM cathode with sufficiently high speeds to pulverize the magnetron CM cathode on the surface.
• a vapor of the material constituting the cathode CM which vapor of material is deposited in thin layers on the surface of the substrate 11a.
• magnets 13 which create a permanent magnetic field having the main function of capturing and confining the electrons of the main plasma in the vicinity of the magnetron cathode. This magnetic field thus makes it possible to form and maintain a more strongly ionized magnetized plasma in the vicinity of the magnetron cathode CM.
• FIG. 2 represents the electrical diagram of an exemplary embodiment of a pulse electrical supply 2 according to the invention.
• the power supply used in the invention is designed to allow the advantages of continuous or pulsed preionization to be used.
• the power supply 2 includes an output (Out) which is connected (in a manner known per se) to the cathode CM of the magnetron reactor, first means (S0, GI, TI, T, SI, Cl, RI, Dl , D3) for generating on the output (Out) main voltage pulses, and second means (S2, R, D) for generating a preionization voltage on the output (Out) simultaneously with the main voltage pulses. More particularly, in the embodiment illustrated in FIG.
• the first aforementioned means for generating the main voltage pulses comprise: a DC voltage source SI (delivering in negative voltage output HT), means (S0, Gl, Tl) for generating control pulses, switching means T which are mounted between the DC voltage source SI and the output (Out), a resistor RI and a separation diode Dl which are connected in series between the switching means Tl and the output (Out).
• the junction J between the switching means T and the resistor RI is also connected to ground, via a separation diode D3.
• the output of the voltage source SI is also connected to ground by means of a capacitor Cl.
• the means for generating control pulses more particularly comprise: a supply S0 delivering a control signal S, of the type rectangular, adjustable frequency and duty cycle, - a pulse generator (GI) triggered by the control signal (S), a pulse transformer for controlling the switching means T.
• the switching means T is a bipolar junction transistor of the IGBT type, the gate of which is coupled to the pulse generator GI, by means of the pulse transformer TI.
• the DC voltage source SI allows, only when the transistor T is on, to apply a negative voltage on the magnetron cathode CM, via the resistor RI and the separation diode Dl connected in series with the cathode CM.
• the aforementioned second means for generating the preionization voltage comprise a DC voltage source S2 connected to the output (Out) via a resistor R and a separation diode D in series.
• the voltage source S2 delivers a negative negative preionization voltage (HTP) at the output.
• a switch SW is further mounted in series with the output of the voltage source S2. When the switch SW is closed, the negative preionization voltage (HTP) is applied to the magnetron cathode CM, via the resistor R and the separation diode D.
• the aforementioned switch SW is optional and is used essentially to be able to carry out comparative tests (see below the description of FIGS. 4 and following) between: [switch (SW) open] / operation of the magnetron reactor 1 in an impulse regime alone (conventional operation) and, [switch (SW) closed] / an operation in accordance with the invention, with superposition, on the impulse regime, of a permanent regime allowing the required preionization of the gas to be obtained (in in this case, application of a continuous negative preionization voltage on the magnetron cathode (CM)).
• CM magnetron cathode
• Figure 3 shows schematically an example of oscillograms of the voltage (U) measured between the magnetron cathode CM and the ground, and of the discharge current (I) passing through the magnetron cathode CM.
• the switch (SW) of the supply 2 is closed.
• Phase I / Pre-ionization (FIG. 3): The transistor T is blocked. Only the negative preionization voltage (HTP) is applied to the magnetron cathode CM, via the current limiting resistor R. This negative DC voltage generates within the gas a continuous electrical discharge resulting in a continuous preionization current Ip which passes by the magnetron cathode CM, the separation diode D and the resistance R.
• HTP negative preionization voltage
• the gate of transistor T is controlled by the pulse generator GI (transistor T passing), which makes it possible to temporarily apply the negative voltage (HT) on the magnetron cathode CM via the current limiting resistor RI and the separation diode Dl.
• a pulse of main voltage IT, of duration ti, is thus applied to the cathode CM, which results in a main current pulse IC passing through the cathode. magnetron CM.
• This main current pulse IC is generated with a low delay time ⁇ , relative to the start of the voltage pulse IT.
• Phase III The transistor (T) is again blocked (reverse switching of the transistor by the pulse generator GI).
• the negative high voltage HT is no longer applied to the magnetron cathode CM (end of the main voltage pulse).
• the current (I) remains supported only by the inductive energy accumulated in the equivalent inductance (L) of the magnetron 1 reactor.
• the current (I) decreases with a time constant substantially equal to [L / (RE)] where RE is an equivalent series resistance limited lower by the value of the resistance RI.
• the difference between RE and RI is related to the nonlinear impedance of the plasma.
• the diode D3 (FIG. 2) ensures the passage of the current (I) after the switching of the transistor T, at the same time avoiding overvoltages on this transistor.
• Phase IV After the impulse current has stopped, the impedance of the magnetron 1 reactor remains low due to the state of strong ionization of the magnetized plasma. Consequently, for the same direct preionization current (Ip), the voltage (U) on the magnetron cathode remains low for some time. As the ionization state of the magnetized plasma decreases, the impedance of the magnetron reactor 1 increases, and we gradually return to the initial conditions of the aforementioned preionization phase (I).
• the cycle is resumed with a repetition frequency (f) which is fixed according to the application considered.
• the choice of the resistance RI is important for the proper functioning of the power supply 2. This choice is made so as to comply with the following two opposite constraints: - The duration (Td) of decrease of the current pulse IC during phase (III) (see Figure 3) must be as low as possible (compared to the duration ti of the main voltage pulses IT). More particularly, the resistance RI is chosen so that the duration (Td) of decrease (current cut-off time) is less than 5 ⁇ s, and preferably less than or equal to l ⁇ s, which corresponds substantially to the choice of a ratio ( L / Rl) less than 2.5 ⁇ s, and preferably less than or equal to 0.5 ⁇ s.
• the resistance (RI) must not be too high in order to limit the maximum current (Imax / figure 3) generated during phase II; in practice we will choose (RI) so that this current (Imax) is in all cases less, for example, twice the maximum operating current of the magnetron reactor, in order to avoid any risk of abnormal operation of the magnetron reactor .
• the supply is adjusted so that one and / or the other of the following conditions are met: the maximum density of preionization current (at target level, i.e.
• magnetron cathode is between 0.05 mA / cm 2 and 100 mA / cm 2 ; the maximum current density (at the target) is greater than 0.1 lA / cm 2 , and preferably greater than 1A / cm 2 ; the current rise time is less than 20 ⁇ s and more particularly less than l ⁇ s.
• the capacitance (Cl), of low series inductance, is chosen so as to obtain, during the aforementioned phase II, a pulse current while maintaining a suitable high voltage (U) on the magnetron cathode (CM) for l applied pulse.
• the resistance (R) is chosen so as to define and limit the initial preionization current.
• the voltage (HT) was worth at most -1100 V.
• the voltage (HTP) was worth at most -1100V
• Equivalent inductance (L) of the magnetron 1 reactor was worth approximately 0.5 ⁇ H.
• the resistance RI was worth 5 ⁇ , so that (Td) was worth about 0.1 ⁇ s.
• Resistor R was worth 300k ⁇ .
• the capacitance Cl was worth 10 ⁇ F.
• the duration (ti) [column (4)] corresponds to the width of each main voltage pulse IT;
• the duration (Ti) [column (5)] corresponds, in the case of a double pulse regime (that is to say a succession of trains of two closely spaced voltage pulses), to the duration separating the two pulses a train of pulses;
• the frequency (f) [column (6)] corresponds to the frequency of repetition of the IT voltage pulses (in the case of a single-pulse regime) or of repetition of the trains of two closely spaced IT pulses in the case of a double regime impulse ;
• the delay time ⁇ [column (7)] measures the time separating the start of the current pulse IC with respect to the start of the voltage pulse IT.
• Figures 10 and 16 double pulse regime without preionization / oscilloscope in envelope mode show a very high instability in time of the current pulses (IC) and voltage (IT), which is detrimental to the quality and the reproducibility over time of the deposits of material on the substrate. Comparatively, with preionization (FIGS. 11 and 17), there is a very good stability over time of the current and voltage pulses (IC and IT), which advantageously makes it possible to obtain better reproducibility and better stability of the deposit in time.
• the invention is not limited to the above examples of implementation, and in particular to the electrical parameters described above for the power supply and the magnetron. It is up to a person skilled in the art to size and adjust the power supply on a case-by-case basis for a given magnetron, for example by observing the current (I) and voltage (U) curves by means of an oscilloscope, and by modifying the preionization so as to obtain the desired effects in particular in terms of delay time and / or amplitude and / or stability of the current pulses or even so as to obtain the desired ionization rate for the vapors arriving on the substrate. Also, the preionization can be adjusted so as to limit the effects of poisoning of the target in the case of operation in reactive gas.
• the pre-ionization of the gas prior to the application of each IT voltage pulse can be obtained by any known means of the skilled person. More particularly, the preionization can be ensured by a sufficiently high repetition frequency of the pulses so as to use the residual electronic density between two successive pulses.
• the preionization can also be obtained by creating a plasma by RF excitation or secondary microwave or by any other means making it possible to obtain a sufficient electronic density of preionization (corona discharge, UV preionization ) in addition to the main pulse plasma.
• preionization corona discharge, UV preionization
• an RF excitation of the gas is carried out by means of a copper loop 14 placed in the deposit enclosure near the magnetron cathode and supplied by means of a generator 15 by an RF current of predefined frequency.
• the block 16 shows diagrammatically an impedance matching network which is interposed in a manner known per se between the generator 15 and the loop 14. [0093] Results comparable to those previously described could be obtained with a RF excitation at a frequency of 13.56 MHz, the distance between the magnetron cathode CM and the copper loop 14 being approximately 4 cm.
• the coupling of the RF excitation is not necessarily of the inductive type, but can also be of the capacitive type.
• the pre-ionization can also be obtained by means of microwaves applied in the deposition enclosure, for example at a frequency of 2.45 GHz.
• the preionization was obtained by means of a direct preionization current.
• the preionization current could be a pulsed current, the essential being that the preionization of the gas precedes the application of the voltage pulse.
• the preionization current pulses must precede the main voltage pulses (IT). This remark is also valid in the event of RF or microwave excitation or any other preionization excitation, these can equally be carried out in continuous mode or in pulsed mode.

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• 2004
  • 2004-03-22 EP EP04447072A patent/EP1580298A1/de not_active Withdrawn
• 2005
  • 2005-03-22 CN CN200580009301A patent/CN100587107C/zh not_active Expired - Fee Related
  • 2005-03-22 KR KR1020067019608A patent/KR20070040747A/ko not_active Application Discontinuation
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  • 2005-03-22 WO PCT/BE2005/000038 patent/WO2005090632A1/fr active Application Filing
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