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
  • H01J37/32082—Radio frequency generated discharge
  • H01J37/32091—Radio frequency generated discharge the radio frequency energy being capacitively coupled 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
• • 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
  • H01J37/32018—Glow discharge
  • H01J37/32036—AC powered
• • 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
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32532—Electrodes
  • H01J37/32541—Shape
• • 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
  • H01J37/32431—Constructional details of the reactor
  • H01J37/32532—Electrodes
  • H01J37/32577—Electrical connecting means

Definitions

• the invention relates to a VHF plasma electrode, a VHF device and a VHF method for plasma treatment, in each case according to the preambles of the independent patent claims.
• DE 10 2007 022 252.3 describes a system for plasma coating large-area flat substrates (in particular for the production of photovoltaic modules), wherein the substrate area can be of the order of magnitude of 1 m 2 and more.
• the plasma is generated between an electrode and a counter electrode, between which the substrate to be treated is introduced.
• the system includes means for varying the relative spacing between the electrodes, wherein a first relatively large distance is provided upon loading or unloading the process chamber with the substrate and a second relatively small distance in performing the treatment of the substrate.
• a layer-forming reaction gas or reaction gas mixture is supplied via a gas shower integrated into the electrode.
• the gas shower comprises a gas shower outlet plate with a plurality of outlet openings, with the help of which the reaction gas is distributed evenly distributed in the process chamber.
• the reaction gas is present in a quasineutralen Pla ⁇ mabulk of the plasma discharge between the substrate to be treated and the gas shower as an activated Gasspezie having a relatively high electron density, with which the substrate to be treated is acted upon.
• the speed and quality of the substrate coating depends on a variety of process parameters, in particular pressure, flow and composition of the reaction gases, power density and frequency of the plasma excitation as well as the substrate temperature.
• the object of the present invention is to improve the state of the art.
• the VHF plasma electrode according to the invention with a preferably prismatic, elongated electrode body having an electrode surface which is electrically connected or connectable to at least two connection elements for supplying electrical power, wherein a first connection element at or near a first end side and a second Coupling element is coupled to or near a second end face of the electrode body and preferably the electrode disposed in an electrode member exposing Ausbettungskomponente of dielectric material and preferably a free electrode surface shield member is provided which surrounds the electrode together with the embedding, it is provided that at least one of Connection elements is designed as a VHF - vacuum feedthrough element.
• the term "plasma electrode” refers to an electrode which is intended and suitable for generating a plasma in a plasma treatment apparatus.
• connection element as a vacuum feedthrough element makes it possible to achieve a higher uniformity of the power supply to the plasma.
• a connection element is in the context of the application "close" to a front page coupled means, when the connection element is arranged in a region of the electrode body having a distance from the relevant end face, which is at most 1/3 of the minimum distance between the two end faces.
• the VHF plasma treatment device for flat substrates, wherein a substrate can be arranged in a vacuum chamber between an electrode arrangement and a counterelectrode and a plasma discharge can be excited in a region between at least one plasma electrode arrangement and a counterelectrode, is characterized in that the plasma electrode arrangement has at least one Plasma electrode, which is designed according to one of the preceding claims.
• Co-located or disposable plasma electrodes will hereinafter be referred to as partial electrodes.
• the counterelectrode may be formed in one piece or segmented as consisting of partial electrodes.
• the gap width is less than a dark space distance of the plasma discharge selected between two sub-electrodes.
• the device according to the invention for VHF plasma treatment of a flat substrate wherein the substrate can be arranged in a vacuum chamber between an electrode arrangement and a counterelectrode and a plasma discharge can be excited in a region between the electrode and counterelectrode, is characterized in that at least one partial electrode having at least two Connection elements for the supply of electrical power is electrically connected and in a gap between two adjacent sub-electrodes, an electrically conductive, preferably connected to the electrical ground or connectable separating element is arranged, whereby the generation of a homogeneously burning plasma in the area of the electrode surface is facilitated.
• the greatest distance between a mass land and the nearest sub-electrodes is chosen to be less than the dark-space screening distance (dark-space screening) at which the plasma discharge extinguishes.
• VHF excitation effective dark space shielding is significant over RF excitation, with higher pressures / Excitation amplitudes could also be a distance ⁇ 2 mm ..
• the dark space shield For the determination of the dark space shield one can use per se known analytical approaches or experimental methods (Mark Lieberman, Allan J. Lichtenberg Principles of Plasma Discharges and Materials Processing, John Wiley 2005) or results of computer simulation, for example with a simple parallel plate geometry. For a plasma excitation frequency of 80 MHz and 10 ** 16 charge carriers per cubic meter as the starting criterion for the ignition of the plasma results in an excitation amplitude of about 125 V, a dark space shield of about 1 mm.
• the invention also includes a deposition or etching or
• the linear extent of the substrate surface along the longitudinal sides is greater than lambda / 8 of the excitation frequency in a vacuum, where lambda is the wavelength of the plasma excitation in a vacuum.
• FIG. 1 shows a sectional view of a device according to the invention for the plasma treatment with three partial electrodes
• FIG. 2 shows a representation of a region between two adjacent sub-electrodes with a pumping slot
• FIG. 3 shows a sectional view along A-A in FIG. 1 analogously to the illustration in FIG. 8
• Figure 4 is a sectional view of another device for plasma treatment
• FIG. 6 is an illustration of a connection of a partial electrode by means of a ribbon conductor
• FIG. 7 shows an illustration of a pump line arranged between adjacent sub-electrodes with a pumping slot
• FIG. 8 shows a representation of a plasma device with a partial electrode
• FIG. 10 shows an electrode arrangement in a section in a plane along the line S - S parallel to the plane of FIG. 1.
• FIG. 1 shows a sectional view of a device according to the invention (analogous to FIG. 8) with a VHF plasma electrode arrangement with three plasma electrodes (sub-electrodes) 1a, 1b, 1c instead of an electrode 125, as in FIG. 8 in the region of a vacuum chamber wall 19, 19a.
• Each partial electrode 1a, 1b, 1c comprises an electrode body, which is designed as a preferably elongated prism and consists of a metal, preferably a plasma-solid metal such as aluminum.
• An elongated prism is a prism in which the longitudinal sides are larger than the largest cross-sectional diameter.
• a cuboid electrode body is preferred.
• the electrode body of the electrodes 1 a - 1 c is in each case preferably mirror-symmetrical to a perpendicular to the longitudinal axis of the Electrode level laid S.
• Each sub-electrode 1a-1c is electrically connected to at least two connection elements for supplying electrical power, wherein a first connection element 3a-3c respectively at a first end face 50a-50c and a second connection element, not shown in Figure 1, preferably mirror-symmetrical to the first connection element on a second end face of the electrode body couples. It is understood that more than one connection element can be attached to opposite sides of a partial electrode.
• the connection elements 3a-3c are designed as coaxial lines.
• the connection elements 3a - 3c are formed as metal cylinders. With one of their end faces, the metal cylinders are electrically conductively connected to an end face of the electrode body 1 a - 1 c, for example, welded.
• each sub-electrode 1a-1c is electrically connected to a separate VHF generator.
• the subelectrodes 1 a - 1 c are preferably electrically connected in parallel with a common VHF generator.
• the sub-electrodes 1a-1c are each arranged in a dielectric embedding component 7. Parts of the embedding component can also be formed by air.
• the front side of the electrode body has a large-area electrode surface, which is released from the embedding component 7 and is arranged in the operation of the device with respect to the substrate to be treated and is usually in contact with the plasma.
• a screen element 2 which leaves the electrode surfaces free is provided which encloses one or more of the at least two sub-electrodes 1 a-1 c together with the embedding component 7.
• vacuum-compatible dielectric 7 preferably alumina ceramic, or KER 221, KER 330 or the like,
• Electrodes 1 contain gas distribution 14, 15 with gas supply 15a and / or a
• the surface of the dielectric 7 facing the plasma chamber 100 is covered by metallic plates 9 and held by means of screws or the like.
• FIG. 2 shows a region with a pumping slot 10 in a gap between two adjacent partial electrodes 1 a and 1 b, wherein a pumping slot 20, 20 a is formed in a cover 9 dielectric 7.
• the electrode surface is formed as a gas outlet plate 15 of a gas distribution device, the gas outlet plate 15 gas outlet openings 15a, through the process and / or reaction gas in the vacuum chamber or in the region between the electrode and the Counter electrode can be introduced.
• FIG. 4 shows a further embodiment of the invention, in which the connection elements 3 are arranged in the region of the end faces 50 on the rear side 40 of the electrode body of the part electrode 1.
• the connection element 3 is designed as a vacuum feedthrough and coaxial conductor and fastened by means of sealing elements 8 in a ceramic 7 a in the vacuum chamber wall 19.
• the partial electrode 1 is in this case encompassed by the shielding element 6, which is electrically connected to a part of the outer conductor of the coaxial line 3.
• Electrode 1 is arranged.
• a first pole of a ribbon cable with at least one connection element connected and a second pole of the ribbon cable to be connected to a counter electrode of the partial electrode, wherein the ribbon cable is connected to a Symmetrisierglied with the two-band cable can be connected to a coaxial line connected to a VHF generator.
• the vacuum feedthrough can also be designed as a symmetrical dual-band cable.
• One pole is connected to the electrode, the other to the counter electrode carrying the substrate.
• the symmetry member is used (also called balun), which connects the two-band cable to the coaxial line.
• FIG. 8 shows, in a simplified representation, a plasma apparatus (reactor 100) for the treatment of flat substrates 103.
• the reactor 100 may be designed, for example, as a PECVD reactor.
• An analog device designed for RF voltage is described in DE 10 2007 022 252.3, to which reference is hereby made by reference.
• the VHF plasma treatment device for flat substrates according to the invention is distinguished from the device known from DE 10 2007 022 252.3 in that the plasma electrode cover has at least one plasma electrode in which at least one of the connection elements is designed as a VHF vacuum feedthrough element.
• the reactor 100 comprises a process space 109 having an electrode 105 and a grounded counter electrode 107, which are designed to produce a plasma for treating a surface of one or more flat substrates 103 to be treated.
• the electrode 105 may be connected or connected to an RF voltage source not shown in detail for generating an electric field in the process space 109.
• the substrate 103 is located immediately in front of the grounded Counter electrode 107, it being understood that a different interconnection of the electrodes may be provided.
• the electrodes 105, 107 are preferably designed for treating substrates having an area of at least 1 m 2 as a treatment or processing step in the production of highly efficient thin-film solar modules, for example for amorphous or microcrystalline silicon thin-film solar cells.
• the electrodes 105, 107 form two opposite walls of the process chamber 109.
• the process chamber 109 is located in a vacuum chamber 11, which has a loading and unloading opening 149, which can be closed with a closure device 135.
• the closure device is optional.
• the vacuum chamber 111 is formed by a housing 1 13 of the reactor 100. To seal against the environment seals 1 15 are provided.
• the vacuum chamber 111 may have any spatial form, for example with a round or polygonal, in particular rectangular cross-section.
• the process space 109 is designed, for example, as a flat parallelepiped. In another embodiment, the vacuum chamber 111 itself is the process space 109.
• the electrode 105 is disposed in a holding structure 131 in the vacuum chamber 111 formed by the case back wall 133.
• the electrode 105 is accommodated in a recess of the holding structure 131 and separated from the vacuum chamber wall by a dielectric.
• a pumping channel 129 is formed by a groove-shaped second recess in the support structure 131.
• the substrate 103 is received by the counter electrode 107 on its front side facing the electrode 105 by a holder 134.
• the gaseous material may be, for example, argon (Ar) and / or hydrogen (H2).
• the gaseous material may be an amount of an activatable gas species (reaction gas).
• the gas species used is a precursor gas which forms layer-forming radicals in a plasma.
• the precursor gas is silane (SiH 4 ), which forms the layer precursor SiH 3 in the plasma by electron impact.
• a cleaning gas is used as the activatable gas species, for example NF3.
• a means for introducing gaseous material is a source of coating material 1 19 provided with a channel 123 which is connected to a gas distribution device.
• the gas distribution device is integrated into the electrode 105, but in other embodiments may also be formed separately from the electrode.
• the gas distribution device has a gas outlet plate 125 in the present embodiment; this comprises a multiplicity of openings opening into the process space 109, through which gaseous material can be introduced into the process space 109.
• the gas distribution device is preferably designed such that a homogeneous loading of the substrate 103 with gas species can be achieved.
• the plurality of outlet openings is uniformly distributed in the gas outlet plate 125, so that the gaseous material is distributed evenly into the process chamber 109.
• the means for introducing gaseous material may also be formed differently from the illustration in FIG. 8, as well as the gas distributor device 125.
• the reactor 100 comprises a device for varying the relative distance between the electrodes, which in the embodiment of FIG. 8 is designed as a sliding bolt 141, which can perform a linear movement in the vacuum chamber 11 by means of a bearing plate 143.
• the sliding bolt 141 is connected to the rear 105 of the counter electrode 107 facing away from the electrode 105. A drive associated with the sliding bolt 141 is not shown.
• the counter electrode 107 covers the recess during the performance of the plasma treatment.
• the counter electrode has contact elements 138 for associated contact elements 137 of the holding structure, so that the counter electrode is at the electrical potential of the vacuum chamber 11 during the performance of the plasma treatment.
• the counter electrode 107 has a device, not shown in FIG. 8, for receiving flat substrates, which is designed in such a way that the substrate (s) at least during the treatment of the surface to be treated or treated oriented downwardly at an angle alpha in a range between 0 ° and 90 ° relative to the direction of the solder are arranged.
• a device not shown in FIG. 8 for receiving flat substrates, which is designed in such a way that the substrate (s) at least during the treatment of the surface to be treated or treated oriented downwardly at an angle alpha in a range between 0 ° and 90 ° relative to the direction of the solder are arranged.
• a plasma (not shown in FIG. 8) is excited by means of a high-frequency voltage in a region between electrode 105 and counterelectrode 107, more precisely between gas outlet plate 125 and substrate 103 supported on counterelectrode 105.
• reaction gas is furthermore preferably additionally introduced homogeneously into the plasma via the gas outlet plate 125.
• the reaction gas is present in a quasi-neutral plasma bulk of the plasma discharge between the substrate to be treated and the gas outlet plate 125 as an activated gas species, with which the surface of the substrate 103 to be treated is acted upon.
• FIG. 9 illustrates the attachment of the cylindrically-symmetrically shaped coaxial connections 3a-3d to a right-angled prismatic assembly.
• a metallic separating element 150 for example an aluminum sheet, is arranged between two adjacent sub-electrodes 1a, 1b, which is preferably electrically connected to the shielding element 2 and / or grounding (ground bar).
• the end face 151 of the separating element 150 is arranged offset relative to the electrode surface, so that it does not protrude over this surface, but is set back against it.
• the offset of the length corresponds to the width of the distance to the nearest partial electrode.
• separating elements of electrically conductive material allow a more stable phase relationship between the sub-electrodes, in particular the reduction of destructive interference between the voltage applied to the electrodes electrical or electromagnetic waves for plasma excitation and thus the formation of a more homogeneous plasma.
• at least one of the separating elements (mass webs) is provided with openings which allow an improved passage of fluid material.
• the separating element (ground web) may be formed as a perforated plate or wire mesh. If the separating elements (mass webs) are provided with passage openings, the formation of a homogeneous plasma can be facilitated.
• Double arrow 141 Sliding bolt 143 Bearing plate 145 Housing wall 147 Double arrow

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• Physics & Mathematics (AREA)
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• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Power Engineering (AREA)
• Plasma Technology (AREA)
• Physical Or Chemical Processes And Apparatus (AREA)
• Chemical Vapour Deposition (AREA)

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• 2009
  • 2009-03-26 DE DE102009014414A patent/DE102009014414A1/de not_active Withdrawn
  • 2009-10-29 WO PCT/EP2009/007759 patent/WO2010049158A2/de active Application Filing
  • 2009-10-29 EP EP09759655A patent/EP2347427A2/de not_active Withdrawn
  • 2009-10-29 JP JP2011533610A patent/JP2012507126A/ja active Pending
  • 2009-10-29 TW TW98137045A patent/TW201024453A/zh unknown

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