EP0008360A1 - Device and method for the polishing of loose workpieces - Google Patents

Device and method for the polishing of loose workpieces Download PDF

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Publication number
EP0008360A1
EP0008360A1 EP79102456A EP79102456A EP0008360A1 EP 0008360 A1 EP0008360 A1 EP 0008360A1 EP 79102456 A EP79102456 A EP 79102456A EP 79102456 A EP79102456 A EP 79102456A EP 0008360 A1 EP0008360 A1 EP 0008360A1
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EP
European Patent Office
Prior art keywords
polishing
workpiece
pad
cushion
holes
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Granted
Application number
EP79102456A
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German (de)
French (fr)
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EP0008360B1 (en
Inventor
Jagtar Singh Basi
Vincent James Lyons
Eric Mendel
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International Business Machines Corp
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International Business Machines Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24B—MACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00—Lapping machines or devices; Accessories
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B24—GRINDING; POLISHING
    • B24D—TOOLS FOR GRINDING, BUFFING OR SHARPENING
    • B24D13/00—Wheels having flexibly-acting working parts, e.g. buffing wheels; Mountings therefor
    • B24D13/14—Wheels having flexibly-acting working parts, e.g. buffing wheels; Mountings therefor acting by the front face

Definitions

  • the invention relates to a device for free polishing, with which two surfaces of a workpiece are polished simultaneously, in which the workpiece lies in the opening of a carrier with a smaller thickness than the workpiece between two rotatable polishing discs, each provided with a polishing pad facing the workpiece and there is an arrangement for supplying a polishing paste to the surfaces of the pads, and a method for simultaneously polishing two surfaces of a workpiece, in particular using the device.
  • the workpiece lies in a hole in a holder and the holder is mounted between the two rotating polishing plates in such a way that it in turn can rotate.
  • a slurry of the polishing material is added p Olster on the surface of the polishing.
  • the platelets move relative to the polishing plates by rotating the plates at different speeds, possibly in opposite directions, or by choosing polishing pads that have different friction properties. Different materials are usually selected for the lower and upper cushion, the surface structures of which differ from one another, so that different frictional forces act on the two surfaces of the plate.
  • the rotation of the pads therefore causes platelets to move relative to the pads, thereby polishing the surfaces of the platelets.
  • the times required for polishing are shorter and the necessary inflow speed of the polishing slurry is lower than when using the known methods using the known devices.
  • the method according to the invention can be used to polish semiconductor wafers, metals, sapphire and gadolinium gallium garnets with very good results.
  • Polishing pads that are useful in the invention are usually made of soft materials that are commercially available and generally made of a fibrous material and / or synthetic polymers such as.
  • the materials can be poromeric, ie permeable to water vapor, or they can also be non-poromeric.
  • Poromeric materials are materials such as synthetic leather, and are for example. described in detail in the article "Structure and Properties of Natural and Artificial Leather by LG Hole et al., which appeared in the Journal of Materials Seien Volume 6, (1971), pages 1 ff. A suitable cushion 11 is shown in FIGS. 1 and 2.
  • the pad 11 consists, for example, of a poromeric material with open cells, which includes a porous top layer 13 made of polyurethane, which is applied to a substrate 15 impregnated with a binder 15.
  • the substrate 15 consists, for example, of polyester fibers, which are coated with Impregnated with polyurethane, a polyether polyurethane, a polyester polyurethane or a synthetic rubber-like resin, the cushion is typically between 1.02 and 1.27 mm thick, with the layer 13 between about 0.38 and about 0.51 mm and the remaining difference from the total thickness is equal to the thickness of the substrate 15 made of the impregnated fibers, other thicknesses may vary depending on the specific len application.
  • a suitable cushion can also consist of a single layer, for example of blown, dense polyurethane or of polyester fibers which are impregnated with polyurethane.
  • a pressure sensitive adhesive layer 16 may be provided to secure the pad to the polishing head. The layer is covered with a protective film, which is removed shortly before the pad is to be attached to the polishing head.
  • the pad 11 has in its surface a pattern consisting of a row of holes 17, which effectively reduces the area of the pad which is in contact with the workpiece during the polishing.
  • the cross section of the holes can vary, for example round, square, rectangular, etc.
  • the holes 17 are circular. The holes should be distributed over the surface, with a substantially uniform distribution being preferred.
  • the holes have a diameter of approximately 2.38 mm and a center-to-center distance of 6.35 mm, so that an area consisting of holes is formed, the total area of which makes up 22 ° of the cushion surface (including the hole surface).
  • the area of the pad made of holes can have a different area and can vary, for example, in the range between 10 and 40% of the pad surface, with the special polishing device which is used using a silicon dioxide-containing polishing slurry giving the best results when the sum of the perforated area makes up about 22% of the cushion surface.
  • the optimal area of the area can be determined empirically for each specific application and device.
  • the proportion of the total area which is accounted for by the holes can be varied by varying either the hole size, the spacing of the holes or the pattern arrangement (straight line, arrangement in the diagonals or an offset arrangement). This is known from the art of making hole patterns. Although a pair of pads, with each pad perforated to varying degrees, can be used for satisfactory polishing, it is more convenient to pierce only one pad. Either the top or bottom pad can be perforated, but it has been found when polishing thin semiconductor wafers that they have less tendency to stick to the top pad after polishing if it is perforated than if it is not perforated.
  • the pads are on rotatably attached polishing plates or polishing heads of the free polishing device (free polisher) attached by means of an adhesive, a pressure-sensitive adhesive being suitable for this purpose.
  • the workpieces lie in the holders or nests of the polishing machine between the upper and lower polishing plates. The nests are somewhat thinner than the workpieces, so that only the workpiece surfaces are contacted and polished by the polishing plates.
  • the holders are mounted, for example, so that on the one hand they rotate around themselves when the polishing discs rotate, under the influence of the frictional forces acting on the surfaces of the platelets, and on the other hand they run through a circular path.
  • Aqueous polishing slurry is conveyed from a storage vessel to the upholstery.
  • a suitable slurry contains a silica abrasive and includes a colloidal suspension of a silica abrasive, an oxidizing agent such as e.g. B. sodium dichloroisocyanate and a base such as. B. sodium carbonate.
  • the slurry has a pH value of less than the 10th
  • a lower and an upper pad which had a microporous polyurethane layer applied to a substrate made of a polyester fiber material impregnated with a polyether polyurethane, were used to polish silicon semiconductor wafers.
  • the upper pad had holes with a total area of 22% of the pad surface.
  • the holes in the pads were 2.38 mm in diameter and approximately 6.35 mm apart from the center and were arranged in a diagonal pattern, giving a hole density of 32 holes per 6.45 cm 2 .
  • the lower pad had a non-perforated surface. The tiles were placed between the pad the for the of the semiconductor built-up platelet surface the upper pad .
  • the upper and lower polishing plates were rotated in opposite directions at approximately 60 to 62 revolutions per minute, thereby imparting a rotational movement of approximately 16 to 22 revolutions per minute on the plate holders.
  • Material removal rates are given in Table I for various feed rates of the slurry containing silica. The optimal flow rate was found to be approximately 200 ml per minute. The polishing time was approximately 30 minutes. In contrast, for a satisfactory polishing using a conventional pair of pads, an inflow rate of 510 ml per minute was required, the removal rate being approximately 30.48 ⁇ m per hour and thus one third below the speed achieved in the method according to the invention.
  • the lower and upper cushions are made of different materials and both have no holes.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Finish Polishing, Edge Sharpening, And Grinding By Specific Grinding Devices (AREA)
  • Mechanical Treatment Of Semiconductor (AREA)

Abstract

1. Apparatus for free polishing, by means of which two surfaces of a wirkpiece are simultaneously polished, wherein the workpiece is placed in a hole of a holder, which ist thinner than the workpiece, between two rotatably mounted polishing plates with one polishing pad (11) each facing the workpiece, and means for feeding a polishing slurry to the pad surfaces, characterized in that at least one of the pads (11) has a surface facing the workpiece which is provided with a pattern of perforations such that the areas by means of which the two pad surfaces contact the workpiece surfaces to be polished are different.

Description

Die Erfindung betrifft eine Vorrichtung zum freien Polieren, mit der zwei Oberflächen eines Werkstücks gleichzeitig poliert werden, bei der das Werkstück in der Öffnung eines Trägers mit einer geringeren Dicke als das Werkstück zwischen zwei, mit je einem dem Werkstück zugewandten Polierpolster versehenen, drehbaren Polierscheibe liegt und eine Anordnung zum Zuführen eines Polierbreies zu den Oberflächen der Polster vorhanden ist, und ein Verfahren zum gleichzeitigen Polieren von zwei Oberflächen eines Werkstücks insbesondere unter Verwendung der Vorrichtung.The invention relates to a device for free polishing, with which two surfaces of a workpiece are polished simultaneously, in which the workpiece lies in the opening of a carrier with a smaller thickness than the workpiece between two rotatable polishing discs, each provided with a polishing pad facing the workpiece and there is an arrangement for supplying a polishing paste to the surfaces of the pads, and a method for simultaneously polishing two surfaces of a workpiece, in particular using the device.

Das freie Polieren von Werkstücken, wie z. B. Halbleiterplättchen aus Silicium oder Germanium, ist beispielsweise im US-Patent 3 691 694 und in dem Artikel "Planetary Free Wafer Polisher", welcher im IBM Technical Disclosure Bulletin, Band 15, Nr. 6, Seiten 1760 und 1761, November 1972 veröffentlicht worden ist, beschrieben. In einer solchen Vorrichtung zum freien Polieren liegt das zu polierende Werkstück zwischen 2 Polierplatten. An den Polierplatten sind Polierpolster befestigt, welche einander zugewandt sind unddie obere und untere Oberfläche des zu polierenden Werkstücks kontaktieren. Das Werkstück ist nicht an den Polierplatten bzw. Polierpolstern befestigt, so daß sich das Werkstück in einer solchen Vorrichtung so bewegen kann, daß es in keiner Position relativ zu den Polierplatten fixiert ist (freies Polieren). Das Werkstück liegt in einem Loch eines Halters und der Halter ist so zwischen die beiden rotierenden Polierplatten montiert, daß er seinerseits rotieren kann. Ein Brei aus Poliermaterial wird auf die Oberfläche der Polierpolster gegeben. Wie in dem Artikel beschrieben wird, bewegen sich die Plättchen relativ zu den Polierplatten dadurch, daß die Platten mit unterschiedlichen Geschwindigkeiten - gegebenenfalls in entgegengesetzten Richtungen - gedreht werden oder indem man Polierpolster wählt, welche unterschiedliche Reibungseigenschaften aufweisen. Für das untere und das obere Polster werden üblicherweise unterschiedliche Materialien ausgewählt, deren Oberflächenstrukturen voneinander differieren, so daß unterschiedliche Reibungskräfte auf die beiden Oberflächen des Plättchens wirken. Die Drehung der Polster bewirkt deshalb, daß sich Plättchen relativ zu den Polstern bewegen, wodurch die Oberflächen der Plättchen poliert werden. Ein Problem tritt auf, wenn die Oberflächentexturen von Polster zu Polster variieren, weil die Polster aus verschiedenen Materiallieferungen stammen. Deshalb kann es passieren, daß, wenn ein Satz von Polstern abgenützt ist, ein an dessen Stelle eingebauter, neuer Satz von Polierpolstern tatsächlich nicht den Unterschied in den Reibungskräften bringt, welcher notwendig ist, um eine zufriedenstellende Polierwirkung auf den Plättchenoberflächen hervorzurufen. Das Problem kann noch größer werden, wenn die Materialien für die beiden Polster von unterschiedlichen Herstellern stammen.The free polishing of workpieces, such as. B. silicon or germanium semiconductor die is described, for example, in US Patent 3,691,694 and in the article "Planetary Free Wafer Polisher", which is published in IBM Technical Disclosure Bulletin, Volume 15, No. 6, pages 1760 and 1761, November 1972 has been described. In such a device the free polishing the to p olierende workpiece between 2 polishing plates is located. Polishing pads are attached to the polishing plates which face each other and contact the upper and lower surfaces of the workpiece to be polished. The workpiece is not attached to the polishing plates or polishing pads, so that the workpiece can move in such a device that it is not fixed in any position relative to the polishing plates (free polishing). The workpiece lies in a hole in a holder and the holder is mounted between the two rotating polishing plates in such a way that it in turn can rotate. A slurry of the polishing material is added p Olster on the surface of the polishing. As described in the article, the platelets move relative to the polishing plates by rotating the plates at different speeds, possibly in opposite directions, or by choosing polishing pads that have different friction properties. Different materials are usually selected for the lower and upper cushion, the surface structures of which differ from one another, so that different frictional forces act on the two surfaces of the plate. The rotation of the pads therefore causes platelets to move relative to the pads, thereby polishing the surfaces of the platelets. A problem arises when the surface textures vary from upholstery to upholstery because the upholstery comes from different supplies of materials. Therefore, when a set of pads is worn out, a new set of polishing pads installed in their place may not actually make the difference in the frictional forces necessary to produce a satisfactory polishing effect on the wafer surfaces. The problem can be compounded if the materials for the two cushions come from different manufacturers.

Es ist die Aufgabe der Erfindung eine Vorrichtung zum freien Polieren von Werkstücken, bei der die auf die beiden zu polierenden Oberflächen wirkenden, unterschiedlich großen Reibungskräfte reproduzierbar eingestellt werden können, und ein in einem fabrikmäßigen Rahmen einsetzbares Verfahren zum Polieren von jeweils zwei Oberflächen eines Werkstücks anzugeben, mit dem polierte Oberflächen sehr guter Qualität reproduzierbar erhalten werden.It is the object of the invention to provide a device for the free polishing of workpieces, in which the differently large frictional forces acting on the two surfaces to be polished can be reproducibly set, and to provide a method for polishing two surfaces of a workpiece which can be used in a factory setting with which polished surfaces of very good quality can be obtained reproducibly.

Diese Aufgabe wird mit einer Vorrichtung der eingangs genannten Art mit dem Merkmal des kennzeichnenden Teils des Anspruchs 1 und mit einem Verfahren der eingangs genannten Art mit dem Merkmal des kennzeichnenden Teils des Anspruchs 8 gelöst.This object is achieved with a device of the type mentioned at the beginning with the feature of the characterizing part of claim 1 and with a method of the type mentioned at the beginning with the feature of the characterizing part of claim 8.

Bei der erfindungsgemäßen Vorrichtung ist es möglich, für beide Polster dasselbe Material zu nehmen, weil der notwendige Unterschied der auf die beiden Oberflächen des Werkstücks wirkenden Reibungskräfte durch die Festlegung der Flächen, mit denen die beiden Polster das Werkstück kontaktieren, eingestellt wird.In the device according to the invention it is possible to use the same material for both cushions because of the necessary The difference in the frictional forces acting on the two surfaces of the workpiece is set by specifying the areas with which the two pads contact the workpiece.

Überraschenderweise sind bei der Anwendung des erfindungsgemäßen Verfahrens unter Verwendung der erfindungsgemäßen Vorrichtung die zum Polieren notwendigen Zeiten kürzer und die notwendige Zuflußgeschwindigkeit des Polierbreies geringer als bei der Anwendung der bekannten Verfahren unter Verwendung der bekannten Vorrichtungen.Surprisingly, when using the method according to the invention using the device according to the invention, the times required for polishing are shorter and the necessary inflow speed of the polishing slurry is lower than when using the known methods using the known devices.

Mittels des erfindungsgemäßen Verfahrens lassen sich Halbleiterplättchen, Metalle, Saphir und Gadolinium-Gallium-Granate mit sehr guten Ergebnissen polieren.The method according to the invention can be used to polish semiconductor wafers, metals, sapphire and gadolinium gallium garnets with very good results.

Weitere vorteilhafte Ausgestaltungen der erfindungsgemäßen Vorrichtung und des erfindungsgemäßen Verfahrens ergeben sich aus den Unteransprüchen.Further advantageous refinements of the device according to the invention and of the method according to the invention result from the subclaims.

Die Erfindung wird anhand von durch Zeichnungen erläuterten Ausführungsbeispiele beschrieben.The invention is described on the basis of exemplary embodiments explained by drawings.

Es zeigen:

  • Fig. 1 in Aufsicht einen Ausschnitt aus einem Polierpolster (polishing pad) mit einem Lochmuster und
  • Fig. 2 einen Querschnitt durch einen Ausschnitt des in der Fig. 1 gezeigten Polsters.
Show it:
  • F ig. 1 in supervision a section of a polishing pad with a perforated pattern and
  • Fig. 2 shows a cross section through a section of the cushion shown in Fig. 1.

Polierpolster, welche im Rahmen der Erfindung nützlich sind, bestehen üblicherweise aus weichen Materialien, welche kommerziell erhältlich sind und im allgemeinen aus einem faserigen Material und/oder synthetischen Polymeren, wie z. B. Polyurethan, Polyamid, Polyester, Polyäther, Polyvinylchlorid oder Mischungen dieser Stoffe, bestehen. Die Materialien können poromerisch (poromeric) d. h. wasserdampfdurchlässig, oder auch nicht poromerisch sein. Poromerische Materialien sind Materialien wie beispielsweise synthetisches Leder, und sind beispielsweise. in dem Artikel "Structure and Properties of Natural and Artificial Leather von L. G. Hole u. a., welcher im Journal of Materials Seien Band 6, (1971), Seiten 1 ff. erschienen ist, im Detail beschrieben. Ein geeignetes Polster 11 ist in den Fign. 1 und 2 dargestellt. Das Polster 11 besteht beispielsweise aus einem poromerischen Material mit offenen Zellen, welches eine poröse Oberschicht 13 aus Polyurethan einschließt, welches auf einem mit einem Bindemittel imprägnierten Substrat 15 aufgebracht ist. Das Substrat 15 besteht beispiels weise aus Polyesterfasern, welche mit Polyurethan, einem Polyäther-Polyurethan, einem Polyester-Polyurethan oder einem synthetischen gummiartigen Harz imprägniert sind. Das Polster ist typischerweise zwischen 1,02 und 1,27 mm dick, wobei die Schicht 13 eine Dicke zwischen ungefähr 0,38 und ungefähr 0,51 mm hat und die verbleibende Differenz zur Gesamtdicke gleich der Dicke des Substrats 15 aus den imprägnierten Fasern ist. Andere Dicken können je nach der spezie len Anwendung verwendet werden. Ein geeignetes Polster kanr auch aus einer einzigen Schicht, beispielsweise aus geblasenem (blown), dichtem Polyurethan oder aus Polyesterfasern welche mit Polyurethan imprägniert sind, bestehen. Eine druckempfindliche Klebeschicht 16 kann bereitgestellt werde um das Polster am Polierkopf zu befestigen. Die Schicht ist mit einer schützenden Folie bedeckt, welche, kurz bevor das Polster an den Polierkopf befestigt werden soll, entfernt wird. Das Polster 11 weist in seiner Oberfläche ein aus eir Reihe von Löchern 17 bestehendes Muster auf, welches die Fläche des Polsters, welche während des Polieren mit dem Werkstück in Kontakt ist, wirkungsvoll vermindert. Der Querschnitt der Löcher kann unterschiedlich, beispielsweise rund, quadratisch, rechteckig usw., sein. Die Löcher 17 sind kreisförmig. Die Löcher sollten über die Oberfläche verteilt sein, wobei eine im wesentlichen gleichförmige Verteilung bevorzugt wird. In der in den Figuren gezeigten Ausführungsform haben die Löcher einen Durchmesser von ungefähr 2,38 mm und einen Mittelpunktsabstand von 6,35 mm, so daß ein aus Löchern bestehendes Gebiet entsteht, dessen Gesamtfläche 22ü der Polsteroberfläche (einschließlich der Lochfläche) ausmacht. Das aus Löchern bestehende Gebiet des Polsters kann eine unterschiedliche Fläche aufweisen, und beispielsweise im Bereich zwischen 10 und 40 % der Polsteroberfläche variieren, wobei bei der speziellen Poliervorrichtung, welche unter Anwendung eines Siliciumdioxids enthaltenden Polierschlamms eingesetzt wird die besten Ergebnisse erzielt werden, wenn die Summe der Lochflächen ungefähr 22 % der Polsteroberfläche ausmacht. Die optimale Fläche des Gebiets kann empirisch für jede spezielle Anwendung und für jede spezielle Vorrichtung ermittelt werden. Der Anteil der Gesamtfläche, welcher auf die Löcher entfällt kann variiert werden., indem entweder die Lochgröße, der Abstand der Löcher oder die Musteranordnung (gerade Linie, Anordnung in den Diagonalen oder eine versetzte Anordnung) variiert wird. Dies ist aus der Technik der Herstellung von Lochmustern bekannt. Obwohl ein Paar von Polstern, bei dem jedes Polster - wenn auch in unterschiedlichem Ausmaß - durchlöchert ist, für ein zufriedenstellendes Polieren verwendet werden kann, ist es bequemer, nur ein Polster zu durchlöchern. Entweder das obere oder das untere Polster kann durchlöchert werden, es ist jedoch beim Polieren von dünnen Halbleiterplättchen festgestellt worden, daß diese eine geringere Tendenz zeigen nach dem Polieren an dem oberen Polster festzukleben, wenn dieses durchlöchert ist, als wenn es nicht durchlöchert ist.Polishing pads that are useful in the invention are usually made of soft materials that are commercially available and generally made of a fibrous material and / or synthetic polymers such as. B. polyurethane, polyamide, polyester, polyether, poly vinyl chloride or mixtures of these substances. The materials can be poromeric, ie permeable to water vapor, or they can also be non-poromeric. Poromeric materials are materials such as synthetic leather, and are for example. described in detail in the article "Structure and Properties of Natural and Artificial Leather by LG Hole et al., which appeared in the Journal of Materials Seien Volume 6, (1971), pages 1 ff. A suitable cushion 11 is shown in FIGS. 1 and 2. The pad 11 consists, for example, of a poromeric material with open cells, which includes a porous top layer 13 made of polyurethane, which is applied to a substrate 15 impregnated with a binder 15. The substrate 15 consists, for example, of polyester fibers, which are coated with Impregnated with polyurethane, a polyether polyurethane, a polyester polyurethane or a synthetic rubber-like resin, the cushion is typically between 1.02 and 1.27 mm thick, with the layer 13 between about 0.38 and about 0.51 mm and the remaining difference from the total thickness is equal to the thickness of the substrate 15 made of the impregnated fibers, other thicknesses may vary depending on the specific len application. A suitable cushion can also consist of a single layer, for example of blown, dense polyurethane or of polyester fibers which are impregnated with polyurethane. A pressure sensitive adhesive layer 16 may be provided to secure the pad to the polishing head. The layer is covered with a protective film, which is removed shortly before the pad is to be attached to the polishing head. The pad 11 has in its surface a pattern consisting of a row of holes 17, which effectively reduces the area of the pad which is in contact with the workpiece during the polishing. The cross section of the holes can vary, for example round, square, rectangular, etc. The holes 17 are circular. The holes should be distributed over the surface, with a substantially uniform distribution being preferred. In the embodiment shown in the figures, the holes have a diameter of approximately 2.38 mm and a center-to-center distance of 6.35 mm, so that an area consisting of holes is formed, the total area of which makes up 22 ° of the cushion surface (including the hole surface). The area of the pad made of holes can have a different area and can vary, for example, in the range between 10 and 40% of the pad surface, with the special polishing device which is used using a silicon dioxide-containing polishing slurry giving the best results when the sum of the perforated area makes up about 22% of the cushion surface. The optimal area of the area can be determined empirically for each specific application and device. The proportion of the total area which is accounted for by the holes can be varied by varying either the hole size, the spacing of the holes or the pattern arrangement (straight line, arrangement in the diagonals or an offset arrangement). This is known from the art of making hole patterns. Although a pair of pads, with each pad perforated to varying degrees, can be used for satisfactory polishing, it is more convenient to pierce only one pad. Either the top or bottom pad can be perforated, but it has been found when polishing thin semiconductor wafers that they have less tendency to stick to the top pad after polishing if it is perforated than if it is not perforated.

Die Polster sind auf drehbar befestigten Polierplatten bzw. Polierköpfen der freien Poliervorrichtung (free polisher) mittels eines Klebstoffs befestigt, wobei ein druckempfindlicher Klebstoff für diesen Zweck geeignet ist. Die Werkstücke liegen in den Haltern oder Nestern der Poliermaschine zwischen der oberen und der unteren Polierplatte. Die Nester sind etwas dünner als die Werkstücke, so daß nur die Werkstückoberflächen von den Polierplatten kontaktiert und poliert werden. Die Halter sind beispielsweise so montiert, daß sie, wenn sich die Polierscheiben drehen, unter dem Einfluß der an den Plättchenoberflächen angreifenden Reibungskräfte einerseits sich um sich selbst drehen und andererseits eine Kreisbahn durchlaufen. Solche Poliermaschinen gehören zum Stand der Technik und ein Beispiel davon ist in dem Artikel "Planetary Free Wafer Polisher", welcher im IBM Technical Disclosure Bulletin, Band 15, Nr. 6, Seiten 1760 und 1761, November 1972 veröffentlicht ist, veranschaulicht. Ein wässriger Polierbrei wird von einem Vorratsgefäß zu den Polstern befördert. Solche Breie sind Stand der Technik. Ein geeigneter Brei enthält ein Schleifmittel aus Siliciumdioxid und beinhaltet eine kolloidale Suspension eines Siliciumdioxid-Schleifmittel, ein oxidierendes Agens, wie z. B. Natriumdichlorisocyanat und eine Base wie z. B. Natriumcarbonat. Der Brei hat einen PH-wert von weniger als 10.The pads are on rotatably attached polishing plates or polishing heads of the free polishing device (free polisher) attached by means of an adhesive, a pressure-sensitive adhesive being suitable for this purpose. The workpieces lie in the holders or nests of the polishing machine between the upper and lower polishing plates. The nests are somewhat thinner than the workpieces, so that only the workpiece surfaces are contacted and polished by the polishing plates. The holders are mounted, for example, so that on the one hand they rotate around themselves when the polishing discs rotate, under the influence of the frictional forces acting on the surfaces of the platelets, and on the other hand they run through a circular path. Such polishing machines belong to the prior art and an example of this is illustrated in the article "Planetary Free Wafer Polisher", which is published in IBM Technical Disclosure Bulletin, Volume 15, No. 6, pages 1760 and 1761, November 1972. An aqueous polishing slurry is conveyed from a storage vessel to the upholstery. Such slurries are state of the art. A suitable slurry contains a silica abrasive and includes a colloidal suspension of a silica abrasive, an oxidizing agent such as e.g. B. sodium dichloroisocyanate and a base such as. B. sodium carbonate. The slurry has a pH value of less than the 10th

Ein unteres und ein oberes Polster, welche eine mikroporöse, auf einem Substrat aus einem mit einem Polyäther-Polyurethan imprägnierten Polyesterfasermaterial aufgebrachte Polyurethanschicht aufwiesen, wurden dazu benutzt, um Halbleiterplättchen aus Silicium zu polieren. Dabei wies das obere Polster Löcher mit einer Gesamtfläche von 22 % der Polsteroberfläche auf. Die Löcher in den Polstern hatten einen Durchmesser von 2,38 mm und einen Mittelpunktsabstand von ungefähr 6,35 mm und waren in einem in Richtung der Diagonalen verlaufenden Muster angeordnet, was eine Lochdichte von 32 Löcher pro 6,45 cm2 ergibt. Das untere Polster hatte eine nicht durchlöcherte Oberfläche. Die Plättchen wurden so zwischen die Polster

Figure imgb0001
die für den
Figure imgb0002
der Halbleiterbaute- estimmte Plättchenoberfläche dem oberen Polster
Figure imgb0003
. Die obere und die untere Polierplatte wurden in entgegengesetzten Richtungen mit ungefähr 60 bis 62 Umdrehungen pro Minute gedreht, wodurch eine Drehbewegung von ungefähr 16 bis 22 Umdrehungen pro Minute auf die Plättchenhalter übertragen wurde. Materialabtragungsgeschwindigkeiten werden in der Tabelle I für verschiedene Zuflußgeschwindigkeiten des Siliciumdioxid enthaltenen Breies angegeben. Es wurde gefunden, daß die optimale Zuflußgeschwindigkeit bei ungefähr 200 ml pro Minute lag. Die Polierzeit betrug ungefähr 30 Minuten. Im Gegensatz dazu wurde zum zufriedenstellenden Polieren unter Verwendung eines konventionellen Polsterpaars eine Zuflußgeschwindigkeit von 510 ml pro Minute benötigt, wobei die Abtragungsgeschwindigkeit bei ungefähr 30,48 µm pro Stunde und damit um ein Drittel unter der bei dem erfindungsgemäßem Verfahren erzielten Geschwindigkeit lag. Bei einem konventionellen Polsterpaar bestehen das untere und das obere Polster aus unterschiedlichen Materialien und beide weisen keine Löcher auf.
Figure imgb0004
 A lower and an upper pad, which had a microporous polyurethane layer applied to a substrate made of a polyester fiber material impregnated with a polyether polyurethane, were used to polish silicon semiconductor wafers. The upper pad had holes with a total area of 22% of the pad surface. The holes in the pads were 2.38 mm in diameter and approximately 6.35 mm apart from the center and were arranged in a diagonal pattern, giving a hole density of 32 holes per 6.45 cm 2 . The lower pad had a non-perforated surface. The tiles were placed between the pad
Figure imgb0001
the for the
Figure imgb0002
of the semiconductor built-up platelet surface the upper pad
Figure imgb0003
. The upper and lower polishing plates were rotated in opposite directions at approximately 60 to 62 revolutions per minute, thereby imparting a rotational movement of approximately 16 to 22 revolutions per minute on the plate holders. Material removal rates are given in Table I for various feed rates of the slurry containing silica. The optimal flow rate was found to be approximately 200 ml per minute. The polishing time was approximately 30 minutes. In contrast, for a satisfactory polishing using a conventional pair of pads, an inflow rate of 510 ml per minute was required, the removal rate being approximately 30.48 μm per hour and thus one third below the speed achieved in the method according to the invention. In a conventional pair of cushions, the lower and upper cushions are made of different materials and both have no holes.
Figure imgb0004

Beispiele von anderen Polsterkombinationen, welche dazu benutzt werden, um Plättchen zu polieren, sind in der folgenden Tabelle II angegeben:

Figure imgb0005
(Die %-Zahlen sind bezogen auf die Polsteroberfläche)Examples of other pad combinations used to polish platelets are given in Table II below:
Figure imgb0005
 (The% numbers are related to the upholstery surface)

Bei der Verwendung des erfindungsgemäßen Verfahrens unter Anwendung der erfindungsgemäßen mit mit Löcher versehenen Polierpolstern ausgestatteten Vorrichtung ist es möglich, gegenüber bekannten Vorrichtungen und Verfahren die Poliergeschwindigkeit um 50 % zu erhöhen, was einen erhöhten Durch satz bedeutet, wobei nur ungefähr 40 % der Breizuflußge-schwindigkeit, die gemäß dem Stand der Technik erforderlich ist, gebraucht wird. Zu diesen Vorteilen kommt der weitere Vorteil hinzu, daß es möglich ist, für das untere und das obere Polster dasselbe Material zu verwenden, so daß die Qualität des Polierens nicht mehr länger davon abhängt, ob die für die beiden Polster verwendeten Polstermaterialien aus derselben oder aus unterschiedlichen Lieferungen stammen.When using the method according to the invention using the device provided with holes with polishing pads according to the invention, it is possible to increase the polishing speed by 50% compared to known devices and methods, which means an increased throughput, only about 40% of the inflow of g e -speed that is required according to the prior art is used. In addition to these advantages, there is the further advantage that it is possible to use the same material for the lower and the upper pad, so that the quality of the polishing no longer depends on whether the pad materials used for the two pads are made from the same or from different deliveries.

Zwar ist in den Beispielen nur das Polieren von Halbleiterplättchen beschrieben, es sei aber klargestellt, daß auch Werkstücke aus anderen Materialien, wie z. B. Metallen, Saphir oder Gadolinium-Gallium-Granat, mittels des erfindungsgemäßen Verfahren poliert werden können.Although only the polishing of semiconductor wafers is described in the examples, it should be clarified that workpieces made of other materials, such as, for. B. metals, sapphire or gadolinium gallium garnet, can be polished by the inventive method.

Claims (11)

1. Vorrichtung zum freien Polieren mit der zwei Oberflächen eines Werkstücks gleichzeitig poliert werden, bei der das Werkstück in einem Loch eines Trägers mit einer geringeren Dicke als das Werkstück zwischen zwei, mit je einem dem Werkstück zugewandten Polierpolster versehenen, drehbaren Polierscheiben liegt, und eine Anordnung zum Zuführen eines Polierbreies zu den Polsteroberflächen vorhanden ist, dadurch gekennzeichnet, daß mindestens eines der Polster (11) eine Oberfläche dem Werkstück zuwendet, welche derart mit einem Lochmuster (17) versehen ist, daß die Flächen, mit denen die beiden Polsteroberflächen die zu polierenden Werkstückoberflächen kontaktieren, unterschiedlich groß sind.1. A device for free polishing with which two surfaces of a workpiece are polished simultaneously, in which the workpiece lies in a hole of a carrier with a smaller thickness than the workpiece between two rotating polishing disks, each provided with a polishing pad facing the workpiece, and one Arrangement for feeding a polishing paste to the upholstery surfaces, characterized in that at least one of the upholstery (11) faces the workpiece with a perforated pattern (17) such that the surfaces with which the two upholstery surfaces close Contact polishing workpiece surfaces, are of different sizes. 2. Vorrichtung nach Anspruch 1, dadurch gekennzeichnet, daß nur das obere Polster (11) mit einem Lochmuster (17) versehen ist.2. Device according to claim 1, characterized in that only the upper cushion (11) is provided with a hole pattern (17). 3. Vorrichtung nach Anspruch 1 oder 2, dadurch gekennzeichnet,
daß die Gesamtfläche der Löcher (17) in einem Polster (11) ungefähr 10 bis ungefähr 40 % der Gesamtfläche (einschließlich der Löcher) der dem Werkstück zugewandten Polsteroberfläche ausmacht.3. Device according to claim 1 or 2, characterized in that
that the total area of the holes (17) in a pad (11) is about 10 to about 40% of the total area (including the holes) of the pad surface facing the workpiece. 4. Vorrichtung nach Anspruch 3, dadurch gekennzeichnet, daß die Gesamtfläche der Löcher (17) in einem Polster (11) ungefähr 22 % der Gesamtfläche (einschließlich der Löcher) der dem Werkstück zugewandten Polsteroberfläche ausmacht.4. The device according to claim 3, characterized in that the total area of the holes (17) in a cushion (11) makes up about 22% of the total area (including the holes) of the cushion surface facing the workpiece. 5. Vorrichtung nach einem oder mehreren der Ansprüche 1 bis 4, dadurch gekennzeichnet,
daß das Polster (11) eine Oberflächenschicht (13) aufweist, welche aus porösem Polyurethan besteht.5. The device according to one or more of claims 1 to 4, characterized in
that the cushion (11) has a surface layer (13) which consists of porous polyurethane. 6. Vorrichtung nach einem oder mehreren der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß das Polster (11) ein Substrat aufweist, welches aus Polyesterfasern besteht, welche mit Polyurethan, Polyester-Polyurethan, Polyäther-Polyurethan oder mit einem synthetischen, gummiartigen Harz imprägniert sind.6. The device according to one or more of claims 1 to 5, characterized in that the cushion (11) has a substrate which consists of polyester fibers which are impregnated with polyurethane, polyester-polyurethane, polyether-polyurethane or with a synthetic, rubber-like resin are. 7. Vorrichtung nach Anspruch 5 oder 6, dadurch gekennzeichnet,
daß das Polster (11) zwischen ungefähr 1,0 und ungefähr 1,3 mm dick ist, wobei die Oberflächenschicht (13) zwischen etwa 0,38 und 0,51 mm dick ist.7. The device according to claim 5 or 6, characterized in that
that the pad (11) is between about 1.0 and about 1.3 mm thick, the surface layer (13) being between about 0.38 and 0.51 mm thick. 8. Verfahren zum gleichzeitigen Polieren von zwei Oberflächen eines Werkstücks insbesondere unter Verwendung einer Vorrichtung nach einem oder mehreren der Ansprüche 1 bis 7, dadurch gekennzeichnet,
daß als Polierbrei ein wässriger, ein kolloidales Siliciumdioxid als Schleifmittel enthaltender Brei verwendet wird.8. A method for the simultaneous polishing of two surfaces of a workpiece, in particular using a device according to one or more of claims 1 to 7, characterized in that
that an aqueous slurry containing a colloidal silicon dioxide as an abrasive is used as the polishing slurry. 9. Verfahren nach Anspruch 8, dadurch gekennzeichnet, daß eine Umdrehungsgeschwindigkeit der entgegensetzt zueinander rotierenden Schleifscheiben von ungefähr 60 bis ungefähr 62 Upm eingestellt wird.9. The method according to claim 8, characterized in that a rotational speed of the oppositely rotating grinding wheels of about 60 to about 62 rpm is set. 10. Verfahren nach Anspruch 8 oder 9, dadurch gekennzeichnet,
daß die Zuflußmenge des Polierbreies auf ungefähr 150 bis 250 ml/Minute eingestellt wird.10. The method according to claim 8 or 9, characterized in
that the flow rate of the polishing slurry is adjusted to about 150 to 250 ml / minute. 11. Verfahren nach einem oder mehreren der Ansprüche 8 bis 10, gekennzeichnet durch seine Verwendung beim Polieren von Halbleiterplättchen, Metallen, Saphir oder Gadolinium-Gallium-Granat.11. The method according to one or more of claims 8 to 10, characterized by its use in polishing semiconductor wafers, metals, sapphire or gadolinium gallium garnet.
EP79102456A 1978-08-15 1979-07-16 Device and method for the polishing of loose workpieces Expired EP0008360B1 (en)

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US93370578A 1978-08-15 1978-08-15
US933705 1986-11-21

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JP (1) JPS5531582A (en)
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Cited By (3)

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EP0737547A1 (en) * 1995-04-10 1996-10-16 Applied Materials, Inc. Polishing pad structure and composition and method of fabricating a polishing pad for chemical-mechanical polishing and method of polishing a semiconductor substrate surface
DE10004578C1 (en) * 2000-02-03 2001-07-26 Wacker Siltronic Halbleitermat Production of a semiconductor wafer comprises polishing the edges of the wafer with a cloth with the continuous introduction of an alkaline polishing agent using polishing plates, wetting with a film and cleaning and drying
EP1570951A3 (en) * 2004-03-03 2006-04-05 Schott AG Method for the production of wafers with defective-poor surfaces, the use such wafers and therewith obtained electronic units

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JPS639406Y2 (en) * 1981-01-22 1988-03-19
US6081959A (en) * 1996-07-01 2000-07-04 Umbrell; Richard Buffer centering system
US6105197A (en) * 1998-04-14 2000-08-22 Umbrell; Richard T. Centering system for buffing pad
US6298518B1 (en) 1998-04-14 2001-10-09 Richard T. Umbrell Heat dissipating buffing pad
JP5421628B2 (en) * 2009-03-23 2014-02-19 富士紡ホールディングス株式会社 Abrasive cloth and method for producing abrasive cloth
JP5545536B2 (en) * 2010-04-27 2014-07-09 株式会社Ｓｕｍｃｏ Wafer polishing method, polishing pad, polishing apparatus

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EP0737547A1 (en) * 1995-04-10 1996-10-16 Applied Materials, Inc. Polishing pad structure and composition and method of fabricating a polishing pad for chemical-mechanical polishing and method of polishing a semiconductor substrate surface
DE10004578C1 (en) * 2000-02-03 2001-07-26 Wacker Siltronic Halbleitermat Production of a semiconductor wafer comprises polishing the edges of the wafer with a cloth with the continuous introduction of an alkaline polishing agent using polishing plates, wetting with a film and cleaning and drying
EP1570951A3 (en) * 2004-03-03 2006-04-05 Schott AG Method for the production of wafers with defective-poor surfaces, the use such wafers and therewith obtained electronic units
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CA1106611A (en) 1981-08-11
JPS6234509B2 (en) 1987-07-27
EP0008360B1 (en) 1981-10-14
JPS5531582A (en) 1980-03-05
IT1163691B (en) 1987-04-08
DE2961004D1 (en) 1981-12-24
IT7924956A0 (en) 1979-08-07

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