WO1999009583A1 - Method and device for plasma etching - Google Patents
Method and device for plasma etching Download PDFInfo
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- WO1999009583A1 WO1999009583A1 PCT/AT1998/000193 AT9800193W WO9909583A1 WO 1999009583 A1 WO1999009583 A1 WO 1999009583A1 AT 9800193 W AT9800193 W AT 9800193W WO 9909583 A1 WO9909583 A1 WO 9909583A1
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- waveguide
- reaction chamber
- rod
- target
- conductor
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- 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
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- 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
Definitions
- the invention relates to a method and a device for surface removal or surface build-up, in particular for use in plasma etching or in gas phase deposition (CVD), in which the microwave radiation generated by a magnetron in a waveguide, preferably in the form of a standing wave under reflection at the end of the waveguide facing away from the magnetron, is used for plasma generation.
- CVD gas phase deposition
- the technological background of the invention is as follows: In the manufacture of integrated circuits and in the production of power semiconductors, the requirements for the geometric dimensions and for heat dissipation increase. On the one hand, these assemblies must be thinned from the original material thickness of approx. 0.76 mm to less than 0.2 mm for installation in so-called chip cards, such as ATM cards, which thus become intelligent data carriers and data processing elements.
- chip cards in circulation usually have a thickness of 0.75 mm.
- the thinning is necessary for several reasons:
- the integrated circuit usually located on a silicon single crystal must be able to be installed within the chip card in such a way that it is protected against breakage and damage.
- the metal contact surfaces required above the integrated circuit are embedded in the surface of the chip card and also require a considerable material thickness to function reliably.
- the most widely used material is silicon, which does not have good heat conduction properties. In order to dissipate the heat loss resulting from high operating performance, it is necessary to thin these components. As a result, the series thermal resistance from the power component located on the surface of the silicon single crystal wafer to the coolable underside is drastically reduced.
- the components have been thinned mechanically, usually on wet surface grinding machines. This process can only take place at the end of the manufacturing process, since the silicon wafers on which the integrated circuits and power semiconductors are manufactured usually have a diameter of 150-200 mm. If the supplied silicon wafers already have the final thickness required of less than 0.2 mm (the target is even less than 0.1 mm), the production of these large silicon wafers would be necessary in the many process steps due to the relatively low mechanical Stability almost impossible.
- microwave energy in the form of a standing wave is concentrated at a suitable point in a waveguide.
- a tube is guided through the waveguide in the direction of the electrical field of the microwave.
- the microwave energy is converted in the form of a plasma discharge, as a result of which ions and neutral particles, which are not charged, are formed from them.
- Charged particles (ions) are retained by the field distribution in the plasma space, the neutral particles (radicals) are brought out of the plasma space by their own movement and the gas flow and are available for reactions in a wide pressure range between 5.10 Pa to 5.10 Pa
- the plasma discharge tube the diameter of which corresponds to a quarter of the wavelength of the standing wave, is positioned in the waveguide so that the standing wave forms a first voltage maximum on a first side of the tube, and that the standing wave, which is also supplied in a reflected manner, forms a second, opposite-phase voltage maximum on a second side of the tube, that of the first side lies opposite and faces an end termination of the waveguide system.
- this previously known method which is aimed at the generation of neutral particles, enables etching rates of up to approximately 1 ⁇ m / min of silicon when using SFg as the etching gas.
- the aim of the invention is to provide a method and a device with which substantially higher etching rates can be achieved.
- a rod conductor is arranged at a suitable point in the waveguide in the direction of the electrical field of the microwaves running through the waveguide so that part of its length lies outside the waveguide in the reaction chamber, at least the one lying outside the waveguide Area of the rod conductor is covered by a covering made of dielectric material.
- KPG coaxial plasma generator
- the KPG takes the form of a virtual coaxial line for microwaves, the inner conductor of which is the metallic rod conductor, while its outer conductor is formed by the plasma jacket surrounding the dielectric sheath.
- the conversion of the energy fed into the excitation (dissociation and ionization) of the gas molecules also takes place in the outer conductor.
- the conversion of the energy of the electromagnetic traveling wave in the outer conductor is a desired effect and serves to generate plasma. supply.
- the resulting excited particles and the UV radiation that is generated at the same time are used for plasma processes such as for example the etching of semiconductors.
- the virtual coaxial line created according to the invention is in principle a coaxial traveling wave line with a reflection-free terminating resistor.
- This terminating resistor is formed by the plasma jacket of the virtual coaxial conductor itself and corresponds to a broadband termination, a so-called wave sump.
- the invention thus consists in moving the plasma generation directly into the reaction chamber and in using a rod conductor covered with a dielectric for generating the plasma.
- This combination makes it possible to apply the suction voltage between the target and the plasma sheath that forms around the coaxial conductor during operation, as a result of which the etching takes place not only by radicals but also by ions escaping from the plasma jacket and the etching rate by more than an order of magnitude compared to that previously known method can be increased and values of 30 ⁇ m to 50 ⁇ m / min etching rate for silicon and the use of SFg as etching gas can be achieved.
- the UV radiation generated during the plasma generation brings about a further increase in the etching rate.
- the position of the rod conductor can be the same as that of the tube in the previously known device.
- the rod conductor is coupled in such a way that there is a coaxial coupling out of the waveguide, the rod conductor representing the core of the coaxial cable.
- a coaxial decoupling can take place, for example, through a decoupling loop, through a decoupling T-piece, or through a path transformer in the form of a cone. All this serves to convert the impedance in order to decouple it from the symmetrical rectangular waveguide to transfer the microwave energy into the asymmetrical coaxial conductor system.
- the material from which the rod conductor and its base are made is metallic, for example copper or brass.
- the covering consists of dielectric material, for example aluminum oxide, ceramic or glass.
- the length of the rod conductor in the reaction chamber is essentially of the same dimension as the length of the target to be processed in the direction of the rod conductor in order to achieve a uniform loading of the target in the direction of the rod conductor.
- several rod conductors can be arranged parallel to each other in a plane that is parallel to the target plane, or the target is moved back and forth in its plane and normal to the direction of the rod conductor .
- Lamda is the wavelength of the electromagnetic wave generated by the magnetron in the reaction chamber.
- the frequencies of the magnetrons used are usually at 2.45 GHz, which means a wavelength of 12 cm.
- the minimum distance between the edges of two immediately adjacent rod conductors should therefore be 3 cm.
- FIG. 1 shows a device according to the invention in section
- FIG. 2 shows an arrangement of three devices according to
- Fig. 1 in plan view and Fig. 3 is a schematic section of the arrangement of
- a device according to the invention has a magnetron 1, the decoupling pin 10 of which projects into a waveguide 6.
- the length of the waveguide 6 can be changed by a slide 4, which allows it to be tuned.
- the position of the slide 4 is changed in a known manner by means of an adjusting mechanism 5.
- a rod conductor 7 with its axis running in the direction of the electric field of the microwave is installed in the waveguide 6.
- the rod conductor 7 is provided at the end, which lies in the waveguide 6, with a coupling-out device 3, which works as an impedance converter and is used to couple the conductor conductor 7 to the waveguide 6.
- a coolant inlet 2 for supplying a preferably gaseous coolant into the hollow interior of the rod conductor 7. The coolant flows through the tubular rod conductor 7, exits at its end and flows back into the waveguide in the annular gap between the outer shell of the rod conductor 7 and the inner shell of the dielectric sheath 8.
- the other end of the rod conductor 7 protrudes into the reaction chamber 11 and is sealed off from the outside of the waveguide 6 with a sheathing 8 made of dielectric material.
- a plasma jacket 12 is formed around this jacket 8, the excited particles and UV radiation of which are available for further use, for example for etching.
- the dielectric sheathing 8 it is also possible to design the dielectric sheathing 8 to be gas-permeable and to effect the gas supply into the reaction chamber 11 via the annular gap between the rod conductor and its sheathing. It can be the gas flow entering the reaction chamber is also a partial flow of the supplied cooling gas.
- FIG. 2 Such an arrangement is shown schematically in plan view in FIG. 2, three rod conductors 7, each with its waveguide 6 and magnetron 1, being provided.
- the walls of the reaction chamber 11 are not shown.
- three rod conductors 7 are arranged parallel to one another. A head-to-foot orientation is chosen for reasons of space, but this is not absolutely necessary.
- FIG. 3 again without showing the walls of the reaction chamber 11, a schematic section normal to the axes of the rod conductor 7 is shown.
- a high-frequency alternating voltage is applied between the target 14 on its holder 15 and the earth by means of an HF generator 13. Since both the walls of the reaction chamber 11 and each rod conductor 7 are grounded, there is a voltage build-up between the plasma 12 and the target 14, the AC voltage, which can optionally be superimposed on a DC voltage, acts as a suction voltage and accelerates it Plasma jacket 12 ions formed towards the target and thus increases the etching rate.
- the invention is not limited to the exemplary embodiment shown and described, but can be varied and modified in various ways. So it is not necessary in all circumstances to provide cooling for the To provide rod conductor 7, more or less than three rod conductors can be provided, and no suction voltage, a pure AC voltage, a pure DC voltage or, as already mentioned, a combination of AC and DC voltage can be applied. It is also possible to design the rod conductor (including the covering) not in a straight line but in a meandering or spiral shape. The material of the rod conductor and the sheath can be matched to one another in terms of their thermal expansion coefficient.
- the dimensions of the rod conductor are typically about 6 mm outside diameter, the dielectric sheath has about 15 mm outside diameter.
- the waveguide has dimensions of 45 mm x 90 mm x 200 mm, for example, and is of the R26 type, for example, the type 2M240 or 2M172A from Toshiba can be used as the magnetron. If a plurality of bar conductors are arranged, it can be provided that immediately adjacent bar conductors have different phase positions.
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Abstract
Description
Verfahren und Vorrichtung zum Plasma-Ätzen Method and device for plasma etching
Die Erfindung betrifft ein Verfahren und eine Vorrichtung zum Oberflächenabtrag oder Oberflächenaufbau, insbesondere zur Verwendung beim Plasma-Ätzen oder bei der Gasphasenab- scheidung (CVD) , bei dem die von einem Magnetron in einem Hohlleiter erzeugte Mikrowellenstrahlung, bevorzugt in Form einer stehenden Welle unter Reflexion am dem dem Magnetron abgewandten Ende des Hohlleiters, zur Plasmaer- zeugung verwendet wird.The invention relates to a method and a device for surface removal or surface build-up, in particular for use in plasma etching or in gas phase deposition (CVD), in which the microwave radiation generated by a magnetron in a waveguide, preferably in the form of a standing wave under reflection at the end of the waveguide facing away from the magnetron, is used for plasma generation.
Ein derartiges Verfahren und eine zugehörige Vorrichtung sind aus der DE 41 32 558 CI, die der US 5,489,362 A entspricht, bekannt. Die Offenbarung der US 5,489,362 A wird hiemit durch Bezugnahme zur Gänze in diese Beschreibung übernommen.Such a method and an associated device are known from DE 41 32 558 CI, which corresponds to US Pat. No. 5,489,362. The disclosure of US 5,489,362 A is hereby incorporated by reference in its entirety in this description.
Der technologische Hintergrund der Erfindung ist folgender: Bei der Herstellung integrierter Schaltungen sowie bei der Erzeugung von Leistungshalbleitern steigen die Anforderungen an die geometrischen Abmessungen und an die Wärmeableitung. Diese Baugruppen müssen einerseits zum Einbau in sogenannte Chipkarten, wie zum Beispiel Banko- matkarten, welche dadurch zu intelligenten Datenträgern und Datenverarbeitungselementen werden, von der ursprünglichen Materialdicke von ca. 0,76 mm auf unter 0,2 mm gedünnt werden. Die im Umlauf befindlichen Chipkarten haben üblicherweise eine Dicke von 0,75 mm.The technological background of the invention is as follows: In the manufacture of integrated circuits and in the production of power semiconductors, the requirements for the geometric dimensions and for heat dissipation increase. On the one hand, these assemblies must be thinned from the original material thickness of approx. 0.76 mm to less than 0.2 mm for installation in so-called chip cards, such as ATM cards, which thus become intelligent data carriers and data processing elements. The chip cards in circulation usually have a thickness of 0.75 mm.
Die Dünnung ist aus mehreren Gründen notwendig: Die üblicherweise auf einem Siliziumeinkristall befindliche integrierte Schaltung muß innerhalb der Chipkarte so einbaubar sein, daß sie vor Bruch und Beschädigung geschützt ist. Die über der integrierten Schaltung notwendigen Metallkon- taktflächen sind in die Oberfläche der Chipkarte eingelassen und benötigen zur sicheren Funktion auch noch eine erhebliche Materialdicke. Bei den Leistungshalbleitern besteht das Problem der Abführung der Verlustwärme, welche im Betrieb zwangsläufig entsteht. Der meistverwendete Werkstoff ist Silizium, das keine gute Wärmeleitungseigenschaft hat . Um die durch hohe Betriebsleistung entstehende Verlustwärme abzuführen, ist es notwendig, diese Bauelemente zu dünnen. Dadurch wird der Serienwärmewiderstand von dem an der Oberfläche der Siliziumeinkristallscheibe befindlichem Leistungsbauelement zur kühlbaren Unterseite drastisch verringert.The thinning is necessary for several reasons: The integrated circuit usually located on a silicon single crystal must be able to be installed within the chip card in such a way that it is protected against breakage and damage. The metal contact surfaces required above the integrated circuit are embedded in the surface of the chip card and also require a considerable material thickness to function reliably. With power semiconductors, there is the problem of dissipating the heat loss that inevitably arises during operation. The most widely used material is silicon, which does not have good heat conduction properties. In order to dissipate the heat loss resulting from high operating performance, it is necessary to thin these components. As a result, the series thermal resistance from the power component located on the surface of the silicon single crystal wafer to the coolable underside is drastically reduced.
Bisher wurde die Dünnung der Bauelemente mechanisch, üblicherweise auf Naßflächenschleifmaschinen durchgeführt . Dieser Vorgang kann erst am Ende des Fertigungsprozesses erfolgen, da die Siliziumscheiben, auf denen die inte- grierten Schaltungen und Leistungshalbleiter hergestellt werden, einen Durchmesser von zumeist 150 - 200 mm haben. Wenn die angelieferten Siliziumscheiben bereits die im Endzustand geforderte Enddicke von weniger als 0,2 mm (das Ziel ist sogar weniger als 0,1 mm) haben, wäre die Ferti- gung dieser großen Siliziumscheiben bei den vielen notwendigen Prozeßschritten auf Grund der zυ geringen mechanischen Stabilität nahezu unmöglich.So far, the components have been thinned mechanically, usually on wet surface grinding machines. This process can only take place at the end of the manufacturing process, since the silicon wafers on which the integrated circuits and power semiconductors are manufactured usually have a diameter of 150-200 mm. If the supplied silicon wafers already have the final thickness required of less than 0.2 mm (the target is even less than 0.1 mm), the production of these large silicon wafers would be necessary in the many process steps due to the relatively low mechanical Stability almost impossible.
Diese derzeitig notwendige mechanische Dünnung der Wafer verlangt natürlich einen zuverlässigen Oberflächenschutz der hochempfindlichen aktiven Oberfläche, zum Beispiel durch Schutzbelackung, welche nachträglich wieder sorgfältig entfernt werden muß. Gleichzeitig entstehen durch den Schleifprozeß Mikrokratzspuren, welche wie bei angeritztem Glas, die Bruchgefahr an diesen Stellen stark erhöhen.This currently required mechanical thinning of the wafers naturally requires reliable surface protection of the highly sensitive active surface, for example by protective coating, which must be carefully removed afterwards. At the same time, the grinding process creates micro-scratch marks, which, like scratched glass, greatly increase the risk of breakage at these points.
Aus diesem Grund ist es notwendig, daß die Scheibe nach der mechanischen Dünnung zur Zeit naßchemisch nachgeätzt wird, um die Schleifspuren abzurunden und die Bruchgefahr zu verringern. Diese nachfolgende Ätzung ist zusätzlich aus dem Grund notwendig, da die mechanisch bearbeitete Scheibenrückseite in der Kristallstruktur derartig gestört ist, daß die dadurch auftretenden mechanischen Spannungen die Scheibe verbiegen. Erst nachdem die Kristallstörungen durch die notwendige Ätzung entfernt wurden, ist eine Weiterverarbeitung möglich.For this reason, it is necessary that after the mechanical thinning, the wheel is currently wet-etched to round off the grinding marks and to reduce the risk of breakage. This subsequent etching is additionally necessary for the reason that the mechanically processed back of the pane is disturbed in the crystal structure in this way is that the resulting mechanical stresses bend the disc. Further processing is only possible after the crystal faults have been removed by the necessary etching.
Es ist ohne weiteres einsichtig, daß dieses vorbekannte Verfahren umständlich, zeitraubend und vor allem den Fertigungsprozeß durch die mechanisch schleifende Bearbeitung und die notwendige nasschemische Nachbearbeitung des Wafers extrem störend ist, und daß ein großer Bedarf an einem Verfahren besteht, das ohne mechanisch schleifende und nasse Bearbeitungsschritte auskommt und schnell und zuverläßig Material abtragt .It is readily apparent that this previously known method is cumbersome, time-consuming and, above all, extremely disruptive to the manufacturing process due to the mechanical grinding processing and the necessary wet-chemical reworking of the wafer, and that there is a great need for a method which is free of mechanical grinding and wet Processing steps come out and remove material quickly and reliably.
Gemäß der Offenbarung der einleitend genannten Druckschriften wird an passender Stelle in einem Hohlleiter Mikrowellenenergie in Form einer stehenden Welle konzentriert. An dieser Stelle hoher Konzentration wird ein Rohr in Richtung des elektrischen Feldes der Mikrowelle durch den Hohlleiter geführt. Im Rohrabschnitt , der im Inneren des Hohlleiters liegt, wird die Mikrowellenenergie in Form einer Plasmaentladung umgesetzt, wodurch Ionen und aus diesen ungeladene Neutralteilchen entstehen. Geladene Teilchen (Ionen) werden durch die Feldverteilung im Plas- maraum festgehalten, die Neutralteilchen (Radikale) werden durch ihre Eigenbewegung und die Gasströmung aus dem Plasmaraum gebracht und stehen für Reaktionen in einem weiten Druckbereich zwischen 5.10 Pa bis 5.10 Pa zur Verfü- gungAccording to the disclosure of the publications mentioned in the introduction, microwave energy in the form of a standing wave is concentrated at a suitable point in a waveguide. At this point of high concentration, a tube is guided through the waveguide in the direction of the electrical field of the microwave. In the tube section, which lies inside the waveguide, the microwave energy is converted in the form of a plasma discharge, as a result of which ions and neutral particles, which are not charged, are formed from them. Charged particles (ions) are retained by the field distribution in the plasma space, the neutral particles (radicals) are brought out of the plasma space by their own movement and the gas flow and are available for reactions in a wide pressure range between 5.10 Pa to 5.10 Pa
Das Plasmaentladungsrohr, dessen Durchmesser einem Viertel der Wellenlänge der stehenden Welle entspricht, wird im Hohlleiter so positioniert, daß die stehende Welle ein erstes Spannungsmaximum an einer ersten Seite des Rohres ausbildet, und daß die auch reflektiert zugeführte stehende Welle ein zweites, gegenphasiges Spannungsmaximum an einer zweiten Seite des Rohres, die der ersten Seite gegenüberliegt und einem Endabschluß des Hohlleitersystems zugewandt ist, ausbildet.The plasma discharge tube, the diameter of which corresponds to a quarter of the wavelength of the standing wave, is positioned in the waveguide so that the standing wave forms a first voltage maximum on a first side of the tube, and that the standing wave, which is also supplied in a reflected manner, forms a second, opposite-phase voltage maximum on a second side of the tube, that of the first side lies opposite and faces an end termination of the waveguide system.
Dieses vorbekannte Verfahren, das auf die Generierung neu- traler Teilchen ausgerichtet ist, ermöglicht im Falle des Plasmaätzens Ätzraten bis ca. lμm/min von Silizium bei Verwendung von SFg als Ätzgas.In the case of plasma etching, this previously known method, which is aimed at the generation of neutral particles, enables etching rates of up to approximately 1 μm / min of silicon when using SFg as the etching gas.
Es ist Ziel der Erfindung, ein Verfahren und eine Vorrich- tung anzugeben, mit dem wesentlich höhere Ätzraten erreicht werden können.The aim of the invention is to provide a method and a device with which substantially higher etching rates can be achieved.
Erfindungsgemäß ist dazu vorgesehen, beim eingangs definierten Verfahren einen Stableiter an passender Stelle im Hohlleiter in Richtung des elektrischen Feldes der Mikrowellen durch den Hohlleiter verlaufend so anzuordnen, daß ein Teil seiner Länge außerhalb des Hohlleiters in der Reaktionskammer liegt, wobei zumindest der außerhalb des Hohlleiters liegende Bereich des Stableiters durch eine Umhüllung aus dielektrischem Material abgedeckt ist.According to the invention, in the method defined at the outset, a rod conductor is arranged at a suitable point in the waveguide in the direction of the electrical field of the microwaves running through the waveguide so that part of its length lies outside the waveguide in the reaction chamber, at least the one lying outside the waveguide Area of the rod conductor is covered by a covering made of dielectric material.
Es wird so eine hocheffiziente Quelle für angeregte Teilchen (sowohl Ionen als auch Radikale) und UV-Strahlung in Form eines koaxialen Plasma-Generators, im folgenden kurz KPG genannt, geschaffen. Der KPG hat die Form einer virtuellen Koaxialleitung für Mikrowellen, deren Innenleiter der metallische Stableiter ist, während ihr Außenleiter durch den die dielektrische Umhüllung umgebenden Plasmamantel gebildet wird. Im Außenleiter findet auch die Umsetzung der eingespeisten Energie in Anregung (Dissoziation und Ionisation) der Gasmoleküle statt.This creates a highly efficient source for excited particles (both ions and radicals) and UV radiation in the form of a coaxial plasma generator, hereinafter referred to as KPG. The KPG takes the form of a virtual coaxial line for microwaves, the inner conductor of which is the metallic rod conductor, while its outer conductor is formed by the plasma jacket surrounding the dielectric sheath. The conversion of the energy fed into the excitation (dissociation and ionization) of the gas molecules also takes place in the outer conductor.
Im Gegensatz zu einem gewöhnlichen Koaxialkabel, bei dem Außenleiter und Innenleiter aus möglichst verlustarmen Material gebildet sind, ist im Falle des KPG die Umsetzung der Energie der elektromagnetischen Wanderwelle im Außenleiter ein erwünschter Effekt und dient der Plasmaerzeu- gung. Die dabei entstehenden angeregten Teilchen und die gleichzeitig entstehende UV-Strahlung werden für Plasmaprozesse wie zum Beispiel zum Ätzen von Halbleitern genutzt .In contrast to a normal coaxial cable, in which the outer conductor and inner conductor are made of the lowest possible loss material, in the case of the KPG the conversion of the energy of the electromagnetic traveling wave in the outer conductor is a desired effect and serves to generate plasma. supply. The resulting excited particles and the UV radiation that is generated at the same time are used for plasma processes such as for example the etching of semiconductors.
Die erfindungsgemäß geschaffene virtuelle Koaxialleitung stellt dem Prinzip nach eine koaxiale Wanderwellenleitung mit reflexionsfreiem Abschlußwiderstand dar. Dieser Abschlußwiderstand wird vom Plasmamantel des virtuellen Koaxialleiters selbst gebildet und entspricht einem breit- bandigen Abschluß, einem sogenannten Wellensumpf.The virtual coaxial line created according to the invention is in principle a coaxial traveling wave line with a reflection-free terminating resistor. This terminating resistor is formed by the plasma jacket of the virtual coaxial conductor itself and corresponds to a broadband termination, a so-called wave sump.
Es besteht somit, salopp gesprochen, die Erfindung darin, die Plasmaerzeugung direkt in die Reaktionskammer zu ver- lagern und zur Plasmaerzeugung einen mit einem Dielektrikum umhüllten Stableiter zu verwenden. Durch diese Kombination wird es möglich, die Saugspannung zwischen dem Target und der sich im Betrieb um den Koaxialleiter ausbildenden Plasmahülle anzulegen, wodurch das Ätzen nicht nur durch Radikale sondern auch durch aus dem Plasmamantel austretende Ionen erfolgt und die Ätzrate um mehr als eine Größenordnung gegenüber der vorbekannter Verfahren gesteigert werden kann und Werte von 30 μm bis 50 μm/min Ätzrate bei Silizium und Verwendung von SFg als Ätzgas erreichbar sind. Die bei der Plasmaerzeugung entstehende UV-Strahlung bringt eine weitere Erhöhung der Ätzrate mit sich.To put it bluntly, the invention thus consists in moving the plasma generation directly into the reaction chamber and in using a rod conductor covered with a dielectric for generating the plasma. This combination makes it possible to apply the suction voltage between the target and the plasma sheath that forms around the coaxial conductor during operation, as a result of which the etching takes place not only by radicals but also by ions escaping from the plasma jacket and the etching rate by more than an order of magnitude compared to that previously known method can be increased and values of 30 μm to 50 μm / min etching rate for silicon and the use of SFg as etching gas can be achieved. The UV radiation generated during the plasma generation brings about a further increase in the etching rate.
Die Lage des Stableiters kann die gleiche sein, die bei der vorbekannten Vorrichtung das Rohr einnimmt. Der Stab- leiter wird so angekoppelt, daß es zu einer Koaxialauskopplung aus dem Hohlleiter kommt, wobei der Stableiter die Seele des Koaxialkabels darstellt. Solch eine Koaxialauskopplung kann beispielsweise durch eine Auskopplungs- schleife, durch ein Auskopplungs-T-Stück, oder durch einen Wegtransformator in Form eines Konus erfolgen. All dies dient der Impedanzwandlung, um durch Auskopplung vom symmetrischen Rechteckhohlleiter die Mikrowellenenergie in das unsymmetrische Koaxialleitersystem zu überzuführen.The position of the rod conductor can be the same as that of the tube in the previously known device. The rod conductor is coupled in such a way that there is a coaxial coupling out of the waveguide, the rod conductor representing the core of the coaxial cable. Such a coaxial decoupling can take place, for example, through a decoupling loop, through a decoupling T-piece, or through a path transformer in the form of a cone. All this serves to convert the impedance in order to decouple it from the symmetrical rectangular waveguide to transfer the microwave energy into the asymmetrical coaxial conductor system.
Das Material, aus dem der Stableiter und sein Fuß beste- hen, ist metallisch, beispielsweise Kupfer oder Messing. Die Umhüllung besteht aus dielektrischem Material, beispielsweise Aluminiumoxid, Keramik oder Glas.The material from which the rod conductor and its base are made is metallic, for example copper or brass. The covering consists of dielectric material, for example aluminum oxide, ceramic or glass.
Die Länge des Stableiters in der Reaktionskammer ist im wesentlichen von der gleichen Dimension wie die Länge des zu bearbeitenden Targets in Richtung des Stableiters, um zu einer gleichmäßigen Beaufschlagung des Targets in Richtung des Stableiters zu kommen. Um auch in der Richtung normal dazu eine gleichmäßige Beaufschlagung zu erzielen, können mehrere Stableiter parallel zueinander in einer Ebene, die parallel zur Targetebene liegt, angeordnet werden, oder das Target wird in seiner Ebene und normal zur Richtung des Stableiters hin- und her- bewegt.The length of the rod conductor in the reaction chamber is essentially of the same dimension as the length of the target to be processed in the direction of the rod conductor in order to achieve a uniform loading of the target in the direction of the rod conductor. In order to achieve uniform loading in the direction normal to this, several rod conductors can be arranged parallel to each other in a plane that is parallel to the target plane, or the target is moved back and forth in its plane and normal to the direction of the rod conductor .
Bei Verwendung mehrer Stableiter ist es wichtig, daß der Abstand zwischen unmittelbar benachbarten Stableitern nicht kleiner ist als Lamda/4, wobei Lamda die Wellenlänge der vom Magnetron erzeugten elektromagnetischen Welle in der Reaktionskammer ist. Üblicherweise liegen die Frequen- zen der verwendeten Magnetrons bei 2,45 GHz, was eine Wellenlänge von 12 cm bedeutet. Als Mindestabstand zwischen den Rändern zweier unmittelbar benachbarter Stableiter sind daher 3 cm vorzusehen.If several rod conductors are used, it is important that the distance between immediately adjacent rod conductors is not less than Lamda / 4, where Lamda is the wavelength of the electromagnetic wave generated by the magnetron in the reaction chamber. The frequencies of the magnetrons used are usually at 2.45 GHz, which means a wavelength of 12 cm. The minimum distance between the edges of two immediately adjacent rod conductors should therefore be 3 cm.
Die Erfindung wird im Folgenden an Hand der Zeichnung näher erläutert. Dabei zeigt die Fig. 1 eine erfindungsgemäße Vorrichtung im Schnitt, die Fig. 2 eine Anordnung dreier Vorrichtungen gemäßThe invention is explained in more detail below with reference to the drawing. 1 shows a device according to the invention in section, FIG. 2 shows an arrangement of three devices according to
Fig. 1 in Draufsicht und die Fig. 3 ein schematischer Schnitt der Anordnung derFig. 1 in plan view and Fig. 3 is a schematic section of the arrangement of
Fig. 2 normal zur Achse der Stableiter. Wie aus Fig. 1 ersichtlich ist, weist eine erfindungsgemäße Vorrichtung ein Magnetron 1 auf, dessen Auskoppel - stift 10 in einen Hohlleiter 6 ragt.Fig. 2 normal to the axis of the rod ladder. As can be seen from FIG. 1, a device according to the invention has a magnetron 1, the decoupling pin 10 of which projects into a waveguide 6.
Die Länge des Hohlleiters 6 kann durch einen Schieber 4 geändert werden, was seine Abstimmung erlaubt. Die Änderung der Lage des Schiebers 4 erfolgt mittels eines Stell - mechanismus 5 auf bekannte Art und Weise. Im Hohlleiter 6 ist ein Stableiter 7 mit seiner Achse in Richtung des elektrischen Feldes der Mikrowelle verlaufend, eingebaut.The length of the waveguide 6 can be changed by a slide 4, which allows it to be tuned. The position of the slide 4 is changed in a known manner by means of an adjusting mechanism 5. A rod conductor 7 with its axis running in the direction of the electric field of the microwave is installed in the waveguide 6.
Der Stableiter 7 ist an dem Ende, das im Hohlleiter 6 liegt, mit einer Auskoppeleinrichtung 3 versehen, die als Impedanzwandler arbeitet und der Ankopplung des Stablei - ters 7 an den Hohlleiter 6 dient. Es ist weiters ein Kühlmitteleinlaß 2 zur Zuführung eines bevorzugt gasförmigen Kühlmittels ins hohle Innere des Stableiters 7 vorgesehen. Das Kühlmittel strömt durch den rohrförmig ausgebildeten Stableiter 7, tritt an seinem Ende aus und strömt im Ringspalt zwischen dem Außenmantel des Stableiters 7 und dem Innenmantel der dielektrischen Umhüllung 8 zurück in den Hohlleiter.The rod conductor 7 is provided at the end, which lies in the waveguide 6, with a coupling-out device 3, which works as an impedance converter and is used to couple the conductor conductor 7 to the waveguide 6. There is also a coolant inlet 2 for supplying a preferably gaseous coolant into the hollow interior of the rod conductor 7. The coolant flows through the tubular rod conductor 7, exits at its end and flows back into the waveguide in the annular gap between the outer shell of the rod conductor 7 and the inner shell of the dielectric sheath 8.
Das andere Ende des Stableiters 7 ragt in die Reaktions- kammer 11 und ist, gegenüber dem Äußeren des Hohlleiters 6, mit einer aus dielektrischem Material bestehenden Umhüllung 8 abgedichtet.The other end of the rod conductor 7 protrudes into the reaction chamber 11 and is sealed off from the outside of the waveguide 6 with a sheathing 8 made of dielectric material.
Um diese Umhüllung 8 herum bildet sich ein Plasmamantel 12 aus, dessen angeregte Teilchen und UV-Strahlung zur weiteren Verwendung, beispielsweise zum Ätzen, zur Verfügung stehen.A plasma jacket 12 is formed around this jacket 8, the excited particles and UV radiation of which are available for further use, for example for etching.
Es ist auch möglich, die dielektrische Umhüllung 8 gas- durchläßig auszubilden und die Gaszufuhr in die Reaktionskammer 11 über den Ringspalt zwischen dem Stableiter und seiner Umhüllung zu bewirken. Dabei kann es sich bei dem in die Reaktionskammer gelangenden Gasstrom auch um einen Teilstrom des zugeführten Kühlgases handeln.It is also possible to design the dielectric sheathing 8 to be gas-permeable and to effect the gas supply into the reaction chamber 11 via the annular gap between the rod conductor and its sheathing. It can be the gas flow entering the reaction chamber is also a partial flow of the supplied cooling gas.
In Fig. 2 ist eine derartige Anordnung schematisch in Draufsicht dargestellt, wobei drei Stableiter 7, jeder mit seinem Hohlleiter 6 und Magnetron 1, vorgesehen sind. Die Wände der Reaktionskammer 11 sind nicht dargestellt. Um das kreisförmige Target 14 besonders homogen über seine Oberfläche behandeln zu können, sind drei Stableiter 7 parallel zueinander angeordnet. Aus Platzgründen ist dabei eine Kopf-an-Fuß-Orientierung gewählt, doch ist dies nicht zwingend notwendig.Such an arrangement is shown schematically in plan view in FIG. 2, three rod conductors 7, each with its waveguide 6 and magnetron 1, being provided. The walls of the reaction chamber 11 are not shown. In order to be able to treat the circular target 14 particularly homogeneously over its surface, three rod conductors 7 are arranged parallel to one another. A head-to-foot orientation is chosen for reasons of space, but this is not absolutely necessary.
Es ist auch möglich, einem Hohlleiter mehrere Stableiter zuzuordnen, wenn ein genügend starkes Magnetron zur Verfügung steht. Die Abstimmung des Hohlleiters ist dann zwar nicht mehr so einfach, aber durchaus bewerkstelligbar, besonders wenn die Stableiter einen nicht zu kleinen Abstand voneinander aufweisen.It is also possible to assign several waveguides to a waveguide if a sufficiently strong magnetron is available. The tuning of the waveguide is then no longer so easy, but it can be done, especially if the rod conductors are not too close apart.
In Fig. 3 ist, wiederum ohne die Wände der Reaktionskammer 11 darzustellen, ein schematischer Schnitt normal zu den Achsen der Stableiter 7 gezeig . Zwischen dem Target 14 auf seinem Halter 15 und der Erde wird mittels eines HF- Generators 13 eine hochfrequente WechselSpannung angelegt. Da sowohl die Wände der Reaktionskammer 11 als auch jeder Stableiter 7 geerdet sind, kommt es zur Spannungsausbil- dung zwischen dem Plasma 12 und dem Target 14, die Wechselspannung, der gegebenenfalls eine Gleichspannung über- lagert werden kann, wirkt als Saugspannung und beschleunigt die im Plasmamantel 12 entstandenen Ionen in Richtung Target und erhöht damit die Ätzrate.In Fig. 3, again without showing the walls of the reaction chamber 11, a schematic section normal to the axes of the rod conductor 7 is shown. A high-frequency alternating voltage is applied between the target 14 on its holder 15 and the earth by means of an HF generator 13. Since both the walls of the reaction chamber 11 and each rod conductor 7 are grounded, there is a voltage build-up between the plasma 12 and the target 14, the AC voltage, which can optionally be superimposed on a DC voltage, acts as a suction voltage and accelerates it Plasma jacket 12 ions formed towards the target and thus increases the etching rate.
Die Erfindung ist nicht auf das dargestellte und beschrie- bene Ausführungsbeispiel beschränkt sondern kann verschiedentlich variiert und abgeändert werden. So ist es nicht unter allen Umständen notwendig, eine Kühlung für den Stableiter 7 vorzusehen, es können mehr oder weniger als drei Stableiter vorgesehen werden, und es kann keine Saugspannung, eine reine WechselSpannung, eine reine Gleichspannung oder, wie bereits erwähnt eine Kombination von Wechsel- und Gleichspannung angelegt werden. Es ist auch möglich, den Stableiter (samt Umhüllung) nicht geradlinig sondern in Mäander- oder Spiralform auszubilden. Das Material des Stableiters und der Umhüllung kann in Bezug auf ihren thermischen Ausdehnungskoeffizienten aufeinander abgestimmt sein. Es muß im Hohlleiter, da ja keine Plasmakammer in ihm vorgesehen ist, auch keine stehende Welle ausgebildet werden sondern eine Wanderwelle, wenn nur die Auskoppeleinrichtung an die gewählten Verhältnisse angepaßt ist, was einem Fachmann auf dem Gebiet der Mikro- wellentechnik in Kenntnis der Erfindung leicht möglich ist .The invention is not limited to the exemplary embodiment shown and described, but can be varied and modified in various ways. So it is not necessary in all circumstances to provide cooling for the To provide rod conductor 7, more or less than three rod conductors can be provided, and no suction voltage, a pure AC voltage, a pure DC voltage or, as already mentioned, a combination of AC and DC voltage can be applied. It is also possible to design the rod conductor (including the covering) not in a straight line but in a meandering or spiral shape. The material of the rod conductor and the sheath can be matched to one another in terms of their thermal expansion coefficient. Since there is no plasma chamber in it, no standing wave must be formed in the waveguide, but a traveling wave if only the decoupling device is adapted to the selected conditions, which is easy for a person skilled in the field of microwave technology with knowledge of the invention is possible .
Übliche Parameter für den Betrieb der Vorrichtung sind: Druck im Reaktionsraum: zwischen 10 Pa bis 250 Pa; als Ätzgas können flourhältige, wie NF3 , CF4 , SFg, als Sauerstoffhältige O , N2O Gase verwendet werden. Die Abmessungen des Stableiters sind typischerweise ca 6 mm Außendurchmesser, die dielektrische Umhüllung weist dabei ca. 15 mm Außendurchmesser auf. Der Hohlleiter hat bei- spielsweise Abmessungen von 45 mm x 90 mm x 200 mm und ist beispielsweise vom Typ R26, als Magnetron kann beispielsweise die Type 2M240 oder 2M172A von Toshiba verwendet werden. Wenn mehrere Stableiter angeordnet sind, so kann vorgesehen sein, daß unmittelbar benachbarte Stableiter unterschiedliche Phasenlage aufweisen.Common parameters for the operation of the device are: pressure in the reaction space: between 10 Pa to 250 Pa; flour-containing gases such as NF 3 , CF 4 , SF g can be used as the etching gas, and oxygen-containing O, N2O gases can be used. The dimensions of the rod conductor are typically about 6 mm outside diameter, the dielectric sheath has about 15 mm outside diameter. The waveguide has dimensions of 45 mm x 90 mm x 200 mm, for example, and is of the R26 type, for example, the type 2M240 or 2M172A from Toshiba can be used as the magnetron. If a plurality of bar conductors are arranged, it can be provided that immediately adjacent bar conductors have different phase positions.
Es ist selbverständlich für den Fachmann auf dem Gebiet des Plasmaätzens in Kenntnis der Erfindung möglich, die Offenbarung der Beschreibung auf seine Bedürfnisse und auf bereits bestehende Vorrichtungen zu adaptieren, ohne damit den Bereich der Erfindung zu verlassen. It is of course possible for a person skilled in the field of plasma etching with knowledge of the invention to adapt the disclosure of the description to his needs and to existing devices, without thereby leaving the scope of the invention.
Claims
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AU87183/98A AU8718398A (en) | 1997-08-13 | 1998-08-13 | Method and device for plasma etching |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| AT135497 | 1997-08-13 | ||
| ATA1354/97 | 1997-08-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1999009583A1 true WO1999009583A1 (en) | 1999-02-25 |
Family
ID=3512080
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/AT1998/000193 Ceased WO1999009583A1 (en) | 1997-08-13 | 1998-08-13 | Method and device for plasma etching |
Country Status (2)
| Country | Link |
|---|---|
| AU (1) | AU8718398A (en) |
| WO (1) | WO1999009583A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10026180A1 (en) * | 2000-05-26 | 2001-12-06 | Steag Rtp Systems Gmbh | Apparatus for coating a semiconductor wafer in the production of microelectronics has a gas inlet system for introducing process gases into the process chamber via inlets |
| DE102011100057A1 (en) * | 2011-04-29 | 2012-10-31 | Centrotherm Thermal Solutions Gmbh & Co. Kg | Plasma treatment device for treating e.g. semiconductor substrate, has electrodes arranged in pairs with same distance from center plane of chamber such that microwaves of electrodes are partially offset with respect to each other |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3923390A1 (en) * | 1988-07-14 | 1990-01-25 | Canon Kk | DEVICE FOR FORMING A LARGE Vaporized VAPOR FILM USING AT LEAST TWO SEPARATELY DETERMINED ACTIVATED GASES |
| DE4136297A1 (en) * | 1991-11-04 | 1993-05-06 | Plasma Electronic Gmbh, 7024 Filderstadt, De | Localised plasma prodn. in treatment chamber - using microwave generator connected to coupling device which passes through the wall of the chamber without using a coupling window |
| DE19532435A1 (en) * | 1995-09-02 | 1997-03-06 | Ver Foerderung Inst Kunststoff | Unit generating plasma for surface treatment of substrates by e.g. plasma polymerisation or hard facing |
-
1998
- 1998-08-13 WO PCT/AT1998/000193 patent/WO1999009583A1/en not_active Ceased
- 1998-08-13 AU AU87183/98A patent/AU8718398A/en not_active Abandoned
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3923390A1 (en) * | 1988-07-14 | 1990-01-25 | Canon Kk | DEVICE FOR FORMING A LARGE Vaporized VAPOR FILM USING AT LEAST TWO SEPARATELY DETERMINED ACTIVATED GASES |
| DE4136297A1 (en) * | 1991-11-04 | 1993-05-06 | Plasma Electronic Gmbh, 7024 Filderstadt, De | Localised plasma prodn. in treatment chamber - using microwave generator connected to coupling device which passes through the wall of the chamber without using a coupling window |
| DE19532435A1 (en) * | 1995-09-02 | 1997-03-06 | Ver Foerderung Inst Kunststoff | Unit generating plasma for surface treatment of substrates by e.g. plasma polymerisation or hard facing |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE10026180A1 (en) * | 2000-05-26 | 2001-12-06 | Steag Rtp Systems Gmbh | Apparatus for coating a semiconductor wafer in the production of microelectronics has a gas inlet system for introducing process gases into the process chamber via inlets |
| DE102011100057A1 (en) * | 2011-04-29 | 2012-10-31 | Centrotherm Thermal Solutions Gmbh & Co. Kg | Plasma treatment device for treating e.g. semiconductor substrate, has electrodes arranged in pairs with same distance from center plane of chamber such that microwaves of electrodes are partially offset with respect to each other |
Also Published As
| Publication number | Publication date |
|---|---|
| AU8718398A (en) | 1999-03-08 |
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