Classifications

• • 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
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32192—Microwave generated discharge
  • H01J37/32211—Means for coupling power to the plasma
• • 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
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32192—Microwave generated discharge
• • 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
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32192—Microwave generated discharge
  • H01J37/32311—Circuits specially adapted for controlling the microwave discharge
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01P—WAVEGUIDES; RESONATORS, LINES, OR OTHER DEVICES OF THE WAVEGUIDE TYPE
  • H01P5/00—Coupling devices of the waveguide type
  • H01P5/12—Coupling devices having more than two ports
  • H01P5/16—Conjugate devices, i.e. devices having at least one port decoupled from one other port

Definitions

• the present invention relates to the field of microwave devices.
• the present invention relates to the field of devices comprising several elementary microwave sources supplied from a common generator.
• the present invention may find particular application in the production of plasma from a given number of elementary plasma sources supplied in microwave from a single power generator.
• These elementary sources can be either independent in the same enclosure (the objective being for example to bypass the physical or technological limits of the maximum microwave power which it is possible to apply to a single plasma source), or distributed in the same enclosure to allow the extension of scale necessary for a targeted application.
• the fields of application of multiple plasma sources can cover not only all the fields already covered by the implementation of single plasma sources, but also new fields which cannot be envisaged with unit sources (for example for reasons of uniformity, cadences, etc.).
• the invention relates to all microwave plasmas and discharges, whatever the pressure range, the microwave frequency, the nature or configuration of the microwave applicator, the presence or absence of a field. magnetic.
• the invention is not limited to the field of plasmas. It can for example also be applied for bonding, drying or vulcanization operations from multiple stations and more generally for any operation where the impedance of the system may vary depending on the time from one position to another.
• the microwave field has already been the subject of much research.
• Another commonly used solution is to take the microwave power either in a cavity, or in a guide, or in a ring resonator, in which standing waves are established, by antennas arranged at the bellies of electric field (zones of maximum electric field).
• This solution generally assumes that each elementary plasma source behaves like an adapted impedance, in other words that it absorbs all of the microwave power sampled. With such a device, it is then possible to supply a predetermined microwave power to each elementary source.
• impedance imbalances can also be encountered during operation, for example in the event of failure of one of the sources, or following an intentional or unintentional variation in operating conditions (composition of the gas , flow, pressure, plasma density, radio frequency polarization, etc.) in multi-sequence processes.
• the aim of the present invention is to improve microwave systems comprising several elementary sources supplied from a common generator, in order to eliminate the drawbacks of the prior art.
• This object is achieved in the context of the present invention thanks to a system comprising:
• a rectangular guide coupled to the generator, adapted to operate in fundamental (H ⁇ 0 ) or transverse electric (TE 10 ) mode, and associated with means ensuring a standing wave regime,
• an isolating means ensuring a power transmission from the socket to the source, without reflection towards the socket and - an impedance matching device of each source, located downstream of the isolating means, between the latter and the associated source.
• FIG. 1 represents the evolution of the reduced conductance of an antenna brought back to the entry of the guide, as a function of the length of this antenna in the guide,
• FIGS. 2 and 3 represent views in cross section of a guide and illustrate two variants of implantation of sockets or antennas thereon,
• FIG. 4 represents an overall schematic view of a device according to the present invention.
• FIG. 5 shows a perspective view of a guide corresponding to a preferred embodiment of the present invention.
• the present invention calls upon the combination of three elements, the first 100 of which provides the required power division (preferably, but not necessarily the equipartition as required), the second 200 of which provides a transmission of independent and thoughtless power to each source 400, whatever the input impedance presented by each of these sources 400, and the third 300, impedance matching device on each source 400, ensures that the power thus available is more or less fully absorbed (for example in plasma) as needed.
• the power divider 100 is obtained from a rectangular waveguide 110 from which a power draw is made, generally on a long side 112 of the guide, at points 114 distant by half a wavelength in the guide, ie ⁇ g / 2.
• a is the width of the long side 112 of the rectangular guide 110 and ⁇ o the wavelength in vacuum, of microwaves.
• the guide 110 is adapted to operate in fundamental mode H 10 or transverse electric TE-io.
• the antennas 116 should preferably be placed at the maximum of the electric field intensity.
• a sample by means of a magnetic antenna 116 (a loop), it is instead necessary to place these antennas 1 16 minimum electric field intensity (maximum magnetic field).
• the sum of the admittances (case of electrical coupling ) reduced by all of the antennas 1 16 brought to the input of the divider 100 is unitary. To achieve this result, it is either necessary to adjust the penetration depth of the electric antenna 1 16 in the guide 1 10, or to move the position of the antennas 1 16 transversely relative to the axis of the guide 110, or yet to combine these two possibilities. One can proceed in an equivalent way for the magnetic coupling.
• the conductance (real part of the impedance) reduced (reduced to the characteristic impedance ) of an antenna 1 16 brought to the entrance of the guide has the expression:
• the length of the antenna 116 must therefore be adjusted so as to obtain the impedance corresponding to the desired power division N.
• An example of evolution of conductance as a function of the length of the antenna 116 is shown in FIG. 1 (for an antenna with a diameter of 3 mm with a head at the end with a diameter of 5 mm and a thickness of 2 mm) for antennas arranged on the axis of one of the long sides 1 12 of the guide 1 10.
• a variant of the invention consists in having 2 antennas 116 on either side of the axis of the long side 112 of the guide 110 every ⁇ g / 2 as in the first configuration presented. If g 0 is the conductance of an antenna 116 on the axis, its value g at the distance d from the axis of the long side 112 of the guide 110 is equal to:
• another complementary variant of the invention consists in having pairs of antennas 116, as in the previous configuration, facing each other on each of the two faces of the large sides 112 of guide 110 as shown diagrammatically in FIG. 3. This possibility is however limited in terms of conductance achievable by the fact that the facing antennas 116 must neither touch nor be too close to each other; the interaction between opposite antennas 116 leads to an increase in the conductance of each antenna 116.
• Another variant of the invention consists in taking the power from the guide by slots, in particular in the context of an application to the transmission of power to the plasma sources 400 by waveguides.
• the second element 200 of the invention is intended to ensure an independent power transmission without reflection to each source 400. This is achieved by the insertion between the output of the antenna 116 of the divider guide 110 and the applicator, d '' a unidirectional isolator 200.
• This generally consists of a circulator 210 with three branches made from ferrites and terminated on its third branch by a suitable charge 212 intended to absorb any reflected power coming from the plasma source 400 A proper functioning of this device requires an insulation between branches generally greater than 20 dB.
• the third element 300 of the invention is intended to allow the adaptation of impedance on each source 400, in order to ensure that the power thus available is more or less completely absorbed in the plasma as required.
• This can be achieved by using conventional impedance matching devices such as the sliding paper clip, or a three-piston system.
• An essential characteristic required of these different possible devices is to be able to act both on the imaginary part and the real part of the impedance. This makes it possible to adjust the impedance of the source 400 as a function of the plasma conditions sought (density, length, etc.).
• a typical complete complete power division device is shown diagrammatically in FIG. 4.
• the microwave generator 10 (and possibly its protection circulator), it successively comprises the power divider 100 with its mobile short-circuit 130 and the transmission lines to each plasma source 400.
• Each line of transmission comprises a circulator 210 and its adapted load 212 (which absorbs the reflected power) as well as the impedance matching device 300 just upstream from the plasma source 400.
• the main advantage of the device according to the invention is allow the supply of a large number of plasma sources 400 to from a single generator 10. Furthermore, the production of this device is carried out using simple elements, several of which are commonly available commercially.
• a device of the invention can be used with any type of microwave applicator.
• An essential advantage of the invention presented is the possibility of distributing the microwave power over any number N of antennas 116, N possibly even being an odd number.
• the invention allows the suppression of one or more plasma lines without altering the functioning of the others.
• the invention which makes it possible to avoid any interference between the power supplies of the various plasma sources 400, makes it possible to quickly perform the impedance matching on each of the plasma sources 400. Finally, the invention allows the production of devices particularly compact.
• a particular, but nonlimiting example of application illustrating the invention comprises a power division device by 24, (shown diagrammatically in FIG. 5), using the standard WR 340 rectangular waveguide or the long side.
• the antennas 1 16 or groups of antennas are positioned along the wave guide 1 10 under the ⁇ g / 2, that is to say every 87.2 mm.
• the reduced impedance g 0 of an antenna 116 of length f determined experimentally, is given in FIG. 1.
• the antenna length £ corresponding to the impedance value given by Equation (6) is approximately equal (Fig. 1):
• the power divider 100 by 24 thus produced is relatively compact since its total length corresponds to 5 half-wavelengths (plus the size of the antenna sockets and their coaxial connector).
• each of the 24 transmission lines coming from the divider 100 successively comprises an isolator 200 with its adapted load 212 and the impedance matching 300 just upstream from the plasma source 400.
• the device according to the invention can be applied in all processes where variations in impedance can occur on one or other of the N applicators supplied independently by the micro power divider. wave.
• the present invention is not limited to particular embodiments which have just been described but extends to all variants in accordance with its spirit.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Plasma Technology (AREA)
• Waveguides (AREA)
• Drying Of Semiconductors (AREA)
• Discharge Heating (AREA)
• Electron Sources, Ion Sources (AREA)
• Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)

Priority Applications (5)

Applications Claiming Priority (2)

Publications (1)

Family

ID=9549779

Family Applications (1)

Country Status (7)

Cited By (3)

Families Citing this family (16)

Citations (3)

Family Cites Families (16)

• 1999
  • 1999-09-13 FR FR9911422A patent/FR2798552B1/fr not_active Expired - Lifetime
• 2000
  • 2000-09-12 AT AT00962606T patent/ATE245855T1/de not_active IP Right Cessation
  • 2000-09-12 US US10/088,326 patent/US6727656B1/en not_active Expired - Lifetime
  • 2000-09-12 WO PCT/FR2000/002507 patent/WO2001020710A1/fr not_active Ceased
  • 2000-09-12 EP EP00962606A patent/EP1216493B1/fr not_active Expired - Lifetime
  • 2000-09-12 DE DE60004073T patent/DE60004073T2/de not_active Expired - Lifetime
  • 2000-09-12 JP JP2001524184A patent/JP4982022B2/ja not_active Expired - Lifetime

Patent Citations (3)

Non-Patent Citations (1)

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