EP0517594B1 - Polishing machine with a tensioned finishing belt and an improved work supporting head - Google Patents

Polishing machine with a tensioned finishing belt and an improved work supporting head Download PDF

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Publication number
EP0517594B1
EP0517594B1 EP19920401532 EP92401532A EP0517594B1 EP 0517594 B1 EP0517594 B1 EP 0517594B1 EP 19920401532 EP19920401532 EP 19920401532 EP 92401532 A EP92401532 A EP 92401532A EP 0517594 B1 EP0517594 B1 EP 0517594B1
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Prior art keywords
machine
wafer
rigid
disk
polishing
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German (de)
French (fr)
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EP0517594A1 (en
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André Baldy
Gérard Barrois
Henry Blanc
Marcel Dominiak
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Commissariat a lEnergie Atomique et aux Energies Alternatives
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Commissariat a lEnergie Atomique et aux Energies Alternatives
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Priority to FR9106866A priority patent/FR2677288B1/en
Priority to FR9106869A priority patent/FR2677293A1/en
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    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B37/00Lapping machines or devices; Accessories
    • B24B37/27Work carriers
    • B24B37/30Work carriers for single side lapping of plane surfaces
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B21/00Machines or devices using grinding or polishing belts; Accessories therefor
    • B24B21/004Machines or devices using grinding or polishing belts; Accessories therefor using abrasive rolled strips
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B24GRINDING; POLISHING
    • B24BMACHINES, DEVICES, OR PROCESSES FOR GRINDING OR POLISHING; DRESSING OR CONDITIONING OF ABRADING SURFACES; FEEDING OF GRINDING, POLISHING, OR LAPPING AGENTS
    • B24B21/00Machines or devices using grinding or polishing belts; Accessories therefor
    • B24B21/18Accessories
    • B24B21/20Accessories for controlling or adjusting the tracking or the tension of the grinding belt

Description

  • La présente invention a pour objet une machine de polissage à bande microabrasive tendue et à tête support de plaquette perfectionnée. The present invention relates to a polishing machine with a tensile microabrasive band and an improved wafer support head.
  • Une machine conforme au préambule de la revendication 1 est connue, par exemple, par PATENT ABSTRACTS OF JAPAN vol. 8, no. 83 (M-290) (1520) 17 Avril 1984 & JP-A-59 001 151. A machine according to the preamble of claim 1 is known, for example, from PATENT ABSTRACTS OF JAPAN vol. 8, no. 83 (M-290) (1520) April 17, 1984 & JP-A-59 001 151.
  • L'invention trouve une application particulière au polissage de composants microélectroniques intégrés dans des plaquettes de semi conducteur (en silicium par exemple). Il peut s'agir, notamment, de têtes magnétiques d'écriture et de lecture.The invention finds a particular application in the polishing of microelectronic components integrated in semiconductor wafers (in silicon for example). They can be, in particular, magnetic writing and reading heads.
  • Des procédés de réalisation de telles têtes sont décrits dans de nombreux documents et notamment dans US-A-4,837,924 et US-A-4,333,229. Le premier document se rapporte à des têtes à structure dite "horizontale" - car formée d'un empilement de couches déposées sur la face supérieure d'une plaquette semi-conductrice- et le second à des têtes à structure dite "verticale" -car formée de couches déposées sur la tranche d'une telle plaquette-.Methods for producing such heads are described in numerous documents and in particular in US-A-4,837,924 and US-A-4,333,229. The first document relates to heads with a so-called "horizontal" structure - because formed by a stack of layers deposited on the upper face of a semiconductor wafer - and the second to heads with a so-called "vertical" structure - because formed of layers deposited on the edge of such a wafer.
  • Les micro-usinages effectués sur de telles plaquettes consistent, dans le premier cas, à niveler (ou "planariser") et à polir divers sous-ensembles intermédiaires obtenus au cours du procédé de réalisation, à définir un entrefer et à amener l'ensemble de la tête dans le plan général du substrat, dit encore plan de vol.The micro-machining carried out on such wafers consists, in the first case, in leveling (or "planarizing") and in polishing various intermediate sub-assemblies obtained during the production process, in defining an air gap and in bringing the assembly of the head in the general plane of the substrate, also called the flight plane.
  • Dans le second cas, les micro-usinages ont pour but de définir un entrefer et d'ajuster la forme des patins de vol.In the second case, the purpose of micro-machining is to define an air gap and to adjust the shape of the flight pads.
  • Bien que pouvant s'appliquer éventuellement à la réalisation de têtes de la deuxième catégorie (têtes verticales), la machine objet de la présente invention est avant tout destinée au polissage d'ensembles ou sous-ensembles correspondants à la première catégorie (têtes horizontales) car c'est dans ce cas que les problèmes technologiques sont les plus ardus.Although possibly applicable for producing heads from the second category (vertical heads), the machine which is the subject of the present invention is above all intended for polishing assemblies or sub-assemblies corresponding to the first category (horizontal heads) because it is in this case that the technological problems are the most difficult.
  • La figure 1 montre, à titre d'exemple de pièce à polir, une tête magnétique d'écriture et de lecture en structure horizontale. L'ensemble représenté correspond à la dernière étape de réalisation avant polissage final. Cet ensemble comprend un substrat de silicium 10 dans lequel un caisson a été gravé, un circuit magnétique 12 en alliage fer-nickel, un double bobinage 14 en cuivre, une couche en silice 16 de 3 à 6»m d'épaisseur, un espaceur amagnétique 18 en silice de 1»m d'épaisseur environ et deux pièces polaires supérieures 20 en fer-nickel. Le plan de polissage final est marqué en trait interrompu et référencé 22.Figure 1 shows, by way of example of a polishing piece, a magnetic writing and reading head in a horizontal structure. The assembly represented corresponds to the last stage of production before final polishing. This set includes a silicon substrate 10 in which a box has been etched, a magnetic circuit 12 made of iron-nickel alloy, a double coil 14 made of copper, a layer of silica 16 3 to 6 ”m thick, a spacer nonmagnetic 18 in silica approximately 1 ”thick and two upper pole pieces 20 in iron-nickel. The final polishing plan is marked in broken lines and referenced 22.
  • L'enlèvement de matière porte sur les pièces polaires 20 et sur les dépassements 23 en silice. Pour ne pas altérer le circuit magnétique, cet enlèvement ne doit pas diminuer l'épaisseur de la couche uniforme de silice de plus de 0,3»m. Le plan final de polissage définit le plan de vol de la tête.The material removal relates to the pole pieces 20 and to the protrusions 23 in silica. In order not to alter the magnetic circuit, this removal must not reduce the thickness of the uniform layer of silica by more than 0.3 ”m. The final polishing plan defines the flight plan of the head.
  • Deux telles têtes sont généralement disposées côte à côte sur deux bandes parallèles dites "skis", définissant deux plans de vol, dans une structure générale en catamaran. Two such heads are generally placed side by side on two parallel strips called "skis", defining two flight plans, in a general catamaran structure.
  • Le polissage, qui consiste en un enlèvement de matière en très petite quantité, est une opération bien connue. On la rencontre en métallographie, en optique et en microélectronique. L'une ou l'autre des deux techniques suivantes est utilisée :
    • la rectification à l'outil diamanté : il s'agit d'un usinage dans lequel on forme un "copeau" semi-continu ou continu par deux mouvements combinés relatifs entre l'outil et la pièce à usiner (un mouvement d'avance et un mouvement de coupe) ; grinding with a diamond tool: this is machining in which a semi-continuous or continuous "chip" is formed by two relative combined movements between the tool and the workpiece (a feed movement and a cutting movement);
    • le rodage et le polissage : il s'agit d'une abrasion plus ou moins fine (ou écrouissage) et contrôlée de la surface par frottement sur des disques très variés non abrasifs par nature, sur lesquels on apporte un abrasif en pâte ou en solution aqueuse ; lapping and polishing: this is a more or less fine abrasion (or hardening) and controlled of the surface by friction on a wide variety of discs that are not abrasive by nature, on which an abrasive is added in paste or in solution aqueous; une variante consiste à placer, sur un plateau de polissage rotatif, un disque de film abrasif et à arroser celui-ci lors du polissage avec un liquide pour refroidir la pièce et éviter l'encrassement. a variant consists in placing, on a rotating polishing plate, a disc of abrasive film and in spraying the latter during the polishing with a liquid in order to cool the part and avoid clogging.
    Polishing, which consists of removing material in very small quantities, is a well-known operation. Polishing, which consists of removing material in very small quantities, is a well-known operation. It is found in metallography, optics and microelectronics. It is found in metallography, optics and microelectronics. Either two following techniques are used: Either two following techniques are used:
    • grinding with a diamond tool: this is machining in which a semi-continuous or continuous "chip" is formed by two relative combined movements between the tool and the workpiece (a movement of advance and a cutting movement); grinding with a diamond tool: this is machining in which a semi-continuous or continuous "chip" is formed by two relative combined movements between the tool and the workpiece (a movement of advance and a cutting movement);
    • lapping and polishing: it is a more or less fine abrasion (or hardening) and controlled of the surface by friction on very varied discs non abrasive by nature, on which an abrasive in paste or solution is provided aqueous; lapping and polishing: it is a more or less fine abrasion (or hardening) and controlled of the surface by friction on very varied discs non abrasive by nature, on which an abrasive in paste or solution is provided aqueous; a variant consists in placing, on a rotary polishing plate, a disc of abrasive film and in spraying the latter during polishing with a liquid to cool the part and avoid fouling. a variant consists in placing, on a rotary polishing plate, a disc of abrasive film and in spraying the latter during polishing with a liquid to cool the part and avoid fouling.
  • Le polissage des plaquettes semiconductrices comprenant un très grand nombre de microcomposants intégrés pose des problèmes particuliers et difficiles :
    • tout d'abord, la plaquette est déformée et déformable, first of all, the plate is deformed and deformable,
    • par ailleurs, le rodage doit affecter simultanément plusieurs matériaux de duretés très différentes : silice, alumine, alliage alumine/carbure de titane, alliage fer/nickel, moreover, lapping must simultaneously affect several materials of very different hardnesses: silica, alumina, alumina / titanium carbide alloy, iron / nickel alloy,
    • les pièces à roder sont de surfaces très petites par rapport à la plaquette de silicium, the parts to be lapped have very small surfaces compared to the silicon wafer,
    • enfin, il s'agit d'usiner, dans leur épaisseur, des couches déposées sur une plaquette, et, généralement, il faut polir simultanément 600 excroissances correspondant à 600 têtes magnétiques, en dépassement de quelques microns et cela avec une précision de l'ordre du nanomètre, sans diminuer l'épaisseur de la couche mince qui recouvre la plaquette de plus de 200 à 300nm. finally, it is a question of machining, in their thickness, the layers deposited on a wafer, and, generally, it is necessary to simultaneously polish 600 protuberances corresponding to 600 magnetic heads, in excess of a few microns and that with a precision of the nanometer order, without reducing the thickness of the thin layer which covers the wafer by more than 200 to 300 nm.
    The polishing of semiconductor wafers comprising a very large number of integrated microcomponents poses particular and difficult problems: The polishing of semiconductor wafers comprising a very large number of integrated microcomponents poses particular and difficult problems:
    • first of all, the plate is deformed and deformable, first of all, the plate is deformed and deformable,
    • in addition, running-in must simultaneously affect several materials with very different hardnesses: silica, alumina, alumina / titanium carbide alloy, iron / nickel alloy, in addition, running-in must simultaneously affect several materials with very different hardnesses: silica, alumina, alumina / titanium carbide alloy, iron / nickel alloy,
    • the parts to be lapped have very small surfaces compared to the silicon wafer, the parts to be lapped have very small surfaces compared to the silicon wafer,
    • finally, it involves machining, in their thickness, layers deposited on a wafer, and, generally, it is necessary to simultaneously polish 600 protuberances corresponding to 600 magnetic heads, exceeding a few microns and this with an accuracy of the order of a nanometer, without reducing the thickness of the thin layer which covers the wafer by more than 200 at 300nm. finally, it involves machining, in their thickness, layers deposited on a wafer, and, generally, it is necessary to simultaneously polish 600 protuberances corresponding to 600 magnetic heads, exceeding a few microns and this with an accuracy of the order of a nanometer, without reducing the thickness of the thin layer which covers the wafer by more than 200 at 300nm.
  • Les machines de polissage connues ne permettent pas de satisfaire à toutes ces exigences. En particulier, l'usage d'un liquide à grains abrasifs ou d'un film abrasif collé sur un support ne convient pas comme on peut s'en convaincre en liaison avec les figures 2 à 6.Known polishing machines do not meet all of these requirements. In particular, the use of an abrasive grain liquid or of an abrasive film bonded to a support is not suitable as may be convinced in connection with FIGS. 2 to 6.
  • La figure 2, tout d'abord, illustre le principe connu du rodage avec liquide chargé de grains abrasifs. La plaquette 10 et ses excroissances 25 sont placées en regard d'un plateau de polissage 23 et le liquide 24, chargé de grains abrasifs, forme un film entre la plaquette et le plan de référence. Le mouvement de translation de la plaquette provoque l'abrasion des excroissances.Figure 2, first of all, illustrates the known principle of lapping with liquid loaded with abrasive grains. The plate 10 and its protuberances 25 are placed opposite a polishing plate 23 and the liquid 24, loaded with abrasive grains, forms a film between the plate and the reference plane. The translational movement of the insert causes abrasion of the growths.
  • Mais des phénomènes hydrodynamiques complexes, liés notamment à la formation de mouvements tourbillonnaires autour des excroissances et à des phénomènes de cavitation, conduisent à un polissage défectueux dont le résultat est illustré sur la figure 3. Sur cette figure, la partie a montre une excroissance 25a avant polissage, dont la forme correspond très sensiblement à celle que l'on rencontre dans le cas des têtes magnétiques intégrées, comme on le verra mieux par la suite. Ce profil prend la forme 25b après un début de polissage (partie b) et, enfin, la forme 25c (partie c) en fin de polissage. On voit qu'on n'a pas obtenu le résultat recherché car le plan de vol a été atteint et des pics subsistent. En particulier, les matériaux tendres se trouvent plus creusés que les matériaux durs.However, complex hydrodynamic phenomena, linked in particular to the formation of vortex movements around the protuberances and to cavitation phenomena, lead to defective polishing, the result of which is illustrated in FIG. 3. In this figure, the part a shows an outgrowth 25a before polishing, the shape of which corresponds very substantially to that encountered in the case of integrated magnetic heads, as will be seen more clearly below. This profile takes the form 25b after the start of polishing (part b ) and, finally, the form 25c (part c ) at the end of polishing. We see that did not obtain the desired result because the flight plan was reached and peaks remain. In particular, soft materials are more hollow than hard materials.
  • Une autre technique connue consiste à utiliser un film plastique microabrasif collé sur un plateau de référence. On voit ainsi, sur la figure 4, un plateau de référence 23 sur lequel un film microabrasif 27 a été collé au moyen de points de colle 28 (aérosols). La couche de colle présente une épaisseur d'environ 100»m. L'épaisseur de la feuille est d'environ 50 à 75»m. L'ensemble présente donc une épaisseur d'environ 150 à 175»m.Another known technique consists in using a microabrasive plastic film bonded to a reference plate. We thus see, in Figure 4, a reference plate 23 on which a microabrasive film 27 has been glued by means of glue dots 28 (aerosols). The adhesive layer has a thickness of about 100 »m. The thickness of the sheet is about 50 to 75 ”m. The assembly therefore has a thickness of approximately 150 to 175 "m.
  • La figure 5 montre ce moyen abrasif avec une plaquette 10 et ses excroissances 25 à polir. On observe que la présence des excroissances et la relativement forte épaisseur de la couche de polissage entraînent un plissement de celle-ci, par compression locale de la feuille et écrasement des points de colle. Dans ce cas encore, le poli obtenu finalement n'est pas satisfaisant. Les figures 6 montrent schématiquement le profil d'un patin poli 29, avant polissage (figure 6a) et après polissage (figure 6b).FIG. 5 shows this abrasive means with a plate 10 and its protrusions 25 to be polished. It is observed that the presence of the protuberances and the relatively large thickness of the polishing layer cause it to crease, by local compression of the sheet and crushing of the glue points. In this case again, the polish finally obtained is not satisfactory. Figures 6 schematically show the profile of a polished pad 29, before polishing (Figure 6a) and after polishing (Figure 6b).
  • On connaît par ailleurs des machines de polissage qui utilisent un film microabrasif, non pas collé sur une surface de reférence mais tendu au-dessus d'un plateau. De telles machines sont décrites dans les documents DE-U-8 717 353 et DOS 26 37 343. Ces machines comprennent une bobine débitrice et une bobine réceptrice entre lesquelles passe, dans un mouvement pas à pas, la bande microabrasive. Cette bande passe au-dessus d'une pièce en matière molle. La pièce à polir, qui est en l'occurrence un pied d'assiette, est tenue par une tête animée d'un mouvement de rotation, Un moyen pneumatique, disposé à la partie inférieure de la machine, permet de plaquer la bande microabrasive sous le pied d'assiette, de sorte que celui-ci vient déformer le film abrasif et s'enfoncer dans la pièce molle. La tension de la bande est obtenue au moyen de pinces ou mors qui permettent simultanément de faire avancer la bande pas à pas.Polishing machines are also known which use a microabrasive film, not glued to a reference surface but stretched over a plate. Such machines are described in documents DE-U-8 717 353 and DOS 26 37 343. These machines comprise a supply coil and a take-up coil between which passes, in a step-by-step movement, the microabrasive strip. This strip passes over a piece of soft material. The polishing piece, which in this case is a base plate, is held by a head animated by a rotational movement, A pneumatic means, arranged at the lower part of the machine, allows to press the microabrasive band under the base of the plate, so that it comes to deform the abrasive film and sink into the soft piece. The tension of the strip is obtained by means of pliers or jaws which simultaneously make it possible to advance the strip step by step.
  • Une telle machine ne convient pas au polissage des plaquettes semiconductrices pour de nombreuses raisons. Tout d'abord, l'enfoncement dans la matière molle est inadmissible pour les raisons déjà indiquées à savoir que les reliefs seraient arrondis et déformés. Il faut donc en fait travailler sur un plateau de référence parfaitement plan et travailler avec un film microabrasif très mince pour que l'on puisse bénéficier de la platitude du plateau de référence.Such a machine is not suitable for polishing semiconductor wafers for many reasons. First of all, sinking into the soft material is inadmissible for the reasons already indicated, namely that the reliefs would be rounded and deformed. It is therefore in fact necessary to work on a perfectly flat reference plate and to work with a very thin microabrasive film so that one can benefit from the flatness of the reference plate.
  • Par ailleurs, si le polissage des pieds d'assiettes autorise des grains d'abrasif gros, le polissage des plaquettes de semiconducteur nécessite des grains beaucoup plus fins. Mais avec de tels grains, il se produit un phénomène de collage de la plaquette sur le film abrasif, au point que la séparation de la plaquette en fin de polissage nécessite la formation d'un coin d'air pour permettre le décollage de la plaquette. Ce phénomène a tendance à provoquer des plissements de la bande microabrasive. Pour éviter ce risque, il faudrait tendre très fortement la bande microabrasive et ceci sur toute sa largeur. Or, ceci est impossible avec la machine du document DE-U-8 717 353 qui ne prévoit à cet effet, que des griffes (ou mors) pinçant la bande sur ses côtés. Avec de tels moyens, on obtiendrait une certaine tension sur les bords de la bande mais pas au centre et de plus les risques de déchirement de la bande seraient réels.In addition, if the polishing of the plate feet allows coarse abrasive grains, the polishing of the semiconductor wafers requires much finer grains. But with such grains, there is a phenomenon of sticking of the wafer on the abrasive film, to the point that the separation of the wafer at the end of polishing requires the formation of an air wedge to allow the wafer to take off. . This phenomenon tends to cause wrinkling of the microabrasive band. To avoid this risk, the microabrasive band should be very tightly stretched over its entire width. However, this is impossible with the machine of document DE-U-8 717 353 which only provides for this purpose claws (or jaws) pinching the strip on its sides. With such means, a certain tension would be obtained on the edges of the strip but not in the center and moreover the risks of tearing of the strip would be real.
  • Par ailleurs, avec la machine antérieure, il est impossible de faire défiler de manière continue la bande abrasive maintenue sous tension. En effet, l'avance de la bande ne peut s'effectuer que pas à pas, puisque celle-ci est tendue par les griffes qui la pincent.Furthermore, with the prior machine, it is impossible to continuously scroll the abrasive strip kept under tension. Indeed, the advance of the strip can only be carried out step by step, since the latter is stretched by the claws which pinch it.
  • La nécessité d'utiliser des grains de polissage très fins et un film très tendu, qui provoque un collage de la plaquette, entraîne d'autres difficultés qui ne sont pas résolues par les machines décrites dans DE-U-8 717 353 et D-OS-26 37 343. En effet, dans de telles machines, la pière à polir, en l'occurrence une assiette, est simplement maintenue dans un support par une dépression provoquée au-dessus de l'assiette. Une telle dépression, qui devrait être très forte pour maintenir la plaquette semiconductrice, casserait celle-ci.The need to use very fine polishing grains and a very tight film, which causes sticking of the wafer, causes other difficulties which are not resolved by the machines described in DE-U-8 717 353 and D- OS-26 37 343. In fact, in such machines, the polishing peg, in this case a plate, is simply held in a support by a depression caused above the plate. Such a depression, which should be very strong to maintain the semiconductor wafer, would break it.
  • Enfin, une tête à mouvement rotatif telle que celle des documents cités, ne conviendrait pas au polissage de plaquettes semiconductrices puisqu'alors le centre de la plaquette ne serait pas poli. Un mouvement rotatif simple ne peut convenir qu'à des pièces en anneau, comme le pied des assiettes. Finally, a head with rotary movement such as that of the cited documents, would not be suitable for polishing semiconductor wafers since then the center of the wafer would not be polished. A simple rotary movement is only suitable for ring pieces, such as the base of plates.
  • La présente invention a justement pour but de remédier à ces inconvénients. A cette fin, l'invention prévoit deux types de dispositions :
    • la première, liée à l'utilisation d'une bande microabrasive tendue, prévoit tout d'abord que la bande est tendue au-dessus d'un plateau de référence offrant une surface plane rigide ; the first, linked to the use of a stretched microabrasive strip, first of all provides for the strip to be stretched above a reference plate offering a rigid flat surface; ensuite elle prévoit des moyens particuliers de tension de la bande entre la bobine débitrice et la bobine réceptrice et cela sans utilisation de griffes, mors ou pinces, ce qui permet de tendre le film sur toute sa largeur et de manière uniforme ; then it provides for special means of tensioning the strip between the supply reel and the receiving reel and this without the use of claws, jaws or pliers, which makes it possible to stretch the film over its entire width and in a uniform manner; ceci permet en outre de faire défiler continuement la bande pour la renouveler ; this also makes it possible to continuously scroll the strip to renew it;
    • la seconde disposition est liée aux moyens pour supporter la plaquette ; the second arrangement is linked to the means for supporting the wafer; ces moyens sont tels qu'un mouvement de translation circulaire est obtenu ; these means are such that a circular translational movement is obtained; ce mouvement parti culier impose à la bande abrasive des efforts dont la direction change en permanence (360° par tour) et qui s'exercent tantôt dans le sens longitudinal (soit dans le sens de déplacement, soit dans le sens contraire) tantôt dans le sens transversal ; this particular movement imposes on the abrasive belt forces whose direction changes continuously (360 ° per revolution) and which are exerted sometimes in the longitudinal direction (either in the direction of displacement or in the opposite direction) sometimes in the transverse direction; ces efforts particuliers, qui auraient tendance à provoquer des plissements de la bande, requièrent que celle-ci soit parfaitement tendue, ce qui ramène au problème précédent ; these particular forces, which would tend to cause folds in the strip, require it to be perfectly stretched, which brings us back to the previous problem; la plaquette étant par nature déformable et déformée, il est prévu un disque de matière souple placé à l'arrière de la plaquette ; the wafer being by nature deformable and deformed, there is provided a disc of flexible material placed at the rear of the wafer; enfin, un système à rotule permet d'avoir un point de rotulage le plus près possible du plan de polissage, ce qui diminue l'apparition de couple parasite dans le mouvement de translation circulaire, qui serait particulièrement néfaste dans le cas de ces efforts intenses communiqués à la plaquette pour la déplacer. finally, a ball joint system makes it possible to have a pivot point as close as possible to the polishing plane, which reduces the appearance of parasitic torque in the circular translational movement, which would be particularly harmful in the case of these intense forces communicated to the wafer to move it.
    The object of the present invention is precisely to remedy these drawbacks. The object of the present invention is precisely to remedy these drawbacks. To this end, the invention provides two types of arrangement: To this end, the invention provides two types of arrangement:
    • the first, linked to the use of a stretched microabrasive strip, firstly provides that the strip is stretched over a reference plate offering a rigid flat surface; the first, linked to the use of a stretched microabrasive strip, firstly provides that the strip is stretched over a reference plate offering a rigid flat surface; then it provides special means of tensioning the strip between the supply reel and the take-up reel without using claws, jaws or pliers, which makes it possible to stretch the film over its entire width and in a uniform manner; then it provides special means of tensioning the strip between the supply reel and the take-up reel without using claws, jaws or pliers, which makes it possible to stretch the film over its entire width and in a uniform manner; this also makes it possible to continuously scroll the strip to renew it; this also makes it possible to continuously scroll the strip to renew it;
    • the second arrangement is linked to the means for supporting the wafer; the second arrangement is linked to the means for supporting the wafer; these means are such that a circular translational movement is obtained; these means are such that a circular translational movement is obtained; this particular movement imposes on the abrasive belt forces whose direction is constantly changing (360 ° per revolution) and which are exerted sometimes in the longitudinal direction (either in the direction of movement, or in the opposite direction) sometimes in the transverse direction; this particular movement imposes on the abrasive belt forces whose direction is constantly changing (360 ° per revolution) and which are exerted sometimes in the longitudinal direction (either in the direction of movement, or in the opposite direction) sometimes in the transverse direction; these particular efforts, which would tend to cause folding of the strip, require that the latter be perfectly stretched, which brings back to the previous problem; these particular efforts, which would tend to cause folding of the strip, require that the latter be perfectly stretched, which brings back to the previous problem; the wafer being by nature deformable and deformed, there is provided a disk of flexible material placed at the rear of the wafer; the wafer being by nature deformable and deformed, there is provided a disk of flexible material placed at the rear of the wafer; finally, a ball joint system makes it possible to have a swiveling point as close as possible to the polishing plane, which reduces the appearance of parasitic torque in the circular translation movement, which would be particularly harmful in the case of these intense forces. finally, a ball joint system makes it possible to have a swiveling point as close as possible to the polishing plane, which reduces the appearance of parasitic torque in the circular translation movement, which would be particularly harmful in the case of these intense forces. communicated to the plate to move it. communicated to the plate to move it.
  • Tous ces moyens concourent à la résolution des problèmes liés au polissage des plaquettes semiconductrices. On peut résumer ces problèmes ainsi : il s'agit, dans une machine de polissage à film abrasif tendu, de maintenir le film abrasif large (15 à 45 cm environ) très fin (25 à 50 microns) tendu sans plissement (à environ 10 à 50 kg environ, soit 4 à 5 kg au mm² de section de bande). A titre d'exemple, pour une largeur de 300 mm et une épaisseur de 25 »m, la tension sera de 35 kg) sur un plan de référence aussi long que la largeur du film. La bande abrasive ainsi tendue doit pouvoir être mise en mouvement de manière continue et très lentement (0,2 à 20 cm par minute) de manière réglable et contrôlée, et sans-à-coups. Ces deux conditions de fonctionnement (tension et vitesse de défilement) ne doivent en aucun cas être perturbées par les efforts imposés à la bande par l'échantillon à polir. Celui-ci, animé d'un mouvement de translation circulaire, doit être maintenu dans une tête support appropriée, apte à tenir compte de la déformation de l'échantillon et évitant les couples parasites.All these means contribute to the resolution of the problems linked to the polishing of semiconductor wafers. These problems can be summarized as follows: in an abrasive film polishing machine stretched, to keep the wide abrasive film (15 to 45 cm approximately) very thin (25 to 50 microns) stretched without wrinkling (approximately 10 to 50 kg, or 4 to 5 kg per mm² of strip section). For example, for a width of 300 mm and a thickness of 25 "m, the tension will be 35 kg) on a reference plane as long as the width of the film. The abrasive belt thus stretched must be able to be set in motion continuously and very slowly (0.2 to 20 cm per minute) in an adjustable and controlled manner, and smoothly. These two operating conditions (voltage and running speed) must in no case be disturbed by the forces imposed on the strip by the sample to be polished. This, animated by a circular translational movement, must be maintained in an appropriate support head, capable of taking into account the deformation of the sample and avoiding parasitic couples.
  • Les feuilles microabrasives (ou "bandes" ou "films") utilisables dans l'invention peuvent être des feuilles du commerce, comme celles que commercialise la Société 3M. Le film dit "Film Imperial Lapping (ILF)" d'épaisseur 12 ou 25 ou 35 ou 50 ou 75»m peut convenir. Ce film est disponible en rouleau. The microabrasive sheets (or "strips" or "films") which can be used in the invention can be commercial sheets, such as those sold by the company 3M. The film called "Imperial Lapping Film (ILF)" of thickness 12 or 25 or 35 or 50 or 75 "m may be suitable. This film is available on roll.
  • De façon précise, la présente invention a donc pour objet une machine de polissage qui, comme certaines machines connues, comprend :
    • une bande microabrasive tendue au-dessus d'un plateau entre une bobine débitrice et une bobine réceptrice, a microabrasive tape stretched over a plate between a supply reel and a reception reel,
    • une tête support apte à maintenir un échantillon à polir, face à polir en regard de la bande abrasive, a support head capable of holding a sample to be polished, facing to be polished facing the abrasive belt,
    • une bobine débitrice équipée de moyens pour exercer sur elle un couple résistant et une bobine réceptrice commandée par un moteur, a supply reel equipped with means for exerting a resistive torque on it and a receiving reel controlled by a motor,
    caractérisée par le fait que : characterized by the fact that:
    • le plateau est un plateau offrant une face supérieure rigide et plane, the plate is a plate offering a rigid and flat upper face,
    • la tête support d'échantillon comprend une pièce rigide et un disque de matière souple ayant une certaine épaisseur, ce disque étant fixé à ladite pièce rigide et recevant la plaquette à polir, la pièce rigide étant reliée par un roulement à rotule et un axe vertical à des moyens pour déplacer la tête support dans un mouvement de translation circulaire. the sample support head comprises a rigid part and a disc of flexible material having a certain thickness, this disc being fixed to said rigid part and receiving the wafer to be polished, the rigid part being connected by a spherical bearing and a vertical axis to means for moving the support head in a circular translational movement.
    Specifically, the present invention therefore relates to a polishing machine which, like certain known machines, comprises: Specifically, the present invention therefore relates to a polishing machine which, like certain known machines, including:
    • a microabrasive strip stretched over a plate between a supply reel and a take-up reel, a microabrasive strip stretched over a plate between a supply reel and a take-up reel,
    • a support head capable of holding a sample to be polished, face to be polished facing the abrasive belt, a support head capable of holding a sample to be polished, face to be polished facing the abrasive belt,
    • a supply reel equipped with means for exerting a resistive torque on it and a take-up reel controlled by a motor, a supply reel equipped with means for exerting a resistive torque on it and a take-up reel controlled by a motor,
    characterized by the fact that: characterized by the fact that:
    • the plate is a plate offering a rigid and flat upper face, the plate is a plate offering a rigid and flat upper face,
    • the sample support head comprises a rigid part and a disk of flexible material having a certain thickness, this disk being fixed to said rigid part and receiving the polishing pad, the rigid part being connected by a spherical bearing and a vertical axis to means for moving the support head in a circular translational movement. the sample support head included a rigid part and a disk of flexible material having a certain thickness, this disk being fixed to said rigid part and receiving the polishing pad, the rigid part being connected by a spherical bearing and a vertical axis to means for moving the support head in a circular translational movement.
  • De toute façon, les caractéristiques et avantages de l'invention apparaîtront mieux à la lumière de la description qui va suivre. Cette description porte sur des exemples de réalisation donnés à titre explicatif et nullement limitatif et se réfère à des dessins annexés, sur lesquels :
    • la figure 1, déjà décrite, montre un exemple de pièce à polir correspondant à une tête magnétique d'écriture et de lecture, FIG. 1, already described, shows an example of a piece to be polished corresponding to a magnetic writing and reading head,
    • la figure 2, déjà décrite, illustre le principe connu du rodage avec film liquide chargé de grains abrasifs, FIG. 2, already described, illustrates the known principle of lapping with a liquid film loaded with abrasive grains,
    • la figure 3, déjà décrite, montre le profit d'un motif au cours d'un polissage effectué par le principe précédent, FIG. 3, already described, shows the benefit of a pattern during polishing carried out by the previous principle,
    • la figure 4, déjà décrite, illustre le principe connu du rodage par film plastique microabrasif collé sur un plateau de référence, FIG. 4, already described, illustrates the known principle of lapping by microabrasive plastic film bonded to a reference plate,
    • la figure 5, déjà décrite, montre la déformation subie lors d'un polissage par une feuille microabrasive collée, FIG. 5, already described, shows the deformation undergone during polishing by a bonded microabrasive sheet,
    • la figure 6, déjà décrite, montre le profil d'un patin poli par la technique des figures 4 et 5, FIG. 6, already described, shows the profile of a shoe polished by the technique of FIGS. 4 and 5,
    • la figure 7 montre la disposition générale de la machine de l'invention avec une feuille microabrasive tendue et un support de plaquette à translation circulaire, FIG. 7 shows the general arrangement of the machine of the invention with a tensioned microabrasive sheet and a wafer support with circular translation,
    • les figures 8a et 8b (respectivement vue de dessus et vue de côté) montrent une machine de polissage conforme à l'invention, FIGS. 8a and 8b (top view and side view respectively) show a polishing machine according to the invention,
    • la figure 9 montre trois positions (a, b, c) de la tête support et illustre la répartition de la force exercée, Figure 9 shows three positions (a, b, c) of the support head and illustrates the distribution of the force exerted,
    • la figure 10 est une courbe montrant les variations de l'enfoncement de la plaquette dans le disque souple en fonction de la force exercée sur la tête support, FIG. 10 is a curve showing the variations in the depression of the wafer in the flexible disc as a function of the force exerted on the support head,
    • la figure 11 montre, en coupe, un exemple de réalisation de la tête support, FIG. 11 shows, in section, an exemplary embodiment of the support head,
    • la figure 12 montre un détail d'un anneau périphérique, figure 12 shows a detail of a peripheral ring,
    • la figure 13 illustre un mode de réalisation de l'anneau périphérique, FIG. 13 illustrates an embodiment of the peripheral ring,
    • la figure 14 montre un sous-ensemble intermédiaire dans la réalisation d'une tête magnétique d'écriture et de lecture, FIG. 14 shows an intermediate sub-assembly in the embodiment of a magnetic write and read head,
    • la figure 15 montre le profil de ce sous-ensemble avant et après polissage, figure 15 shows the profile of this sub-assembly before and after polishing,
    • la figure 16 montre la tête magnétique terminée, figure 16 shows the finished magnetic head,
    • la figure 17 montre le profil de cette tête avant et après polissage. FIG. 17 shows the profile of this head before and after polishing.
    In any case, the characteristics and advantages of the invention will appear better in the light of the description which follows. In any case, the characteristics and advantages of the invention will appear better in the light of the description which follows. This description relates to exemplary embodiments given by way of explanation and in no way limitative and refers to the attached drawings, in which: This description relates to exemplary embodiments given by way of explanation and in no way limiting and refers to the attached drawings, in which:
    • FIG. FIG. 1, already described, shows an example of a polishing piece corresponding to a magnetic writing and reading head, 1, already described, shows an example of a polishing piece corresponding to a magnetic writing and reading head,
    • FIG. FIG. 2, already described, illustrates the known principle of lapping with a liquid film loaded with abrasive grains, 2, already described, illustrates the known principle of lapping with a liquid film loaded with abrasive grains,
    • FIG. FIG. 3, already described, shows the advantage of a pattern during polishing carried out by the previous principle, 3, already described, shows the advantage of a pattern during polishing carried out by the previous principle,
    • FIG. FIG. 4, already described, illustrates the known principle of lapping by microabrasive plastic film bonded to a reference plate, 4, already described, illustrates the known principle of lapping by microabrasive plastic film bonded to a reference plate,
    • FIG. FIG. 5, already described, shows the deformation undergone during polishing by a glued microabrasive sheet, 5, already described, shows the deformation undergone during polishing by a glued microabrasive sheet,
    • FIG. FIG. 6, already described, shows the profile of a pad polished by the technique of FIGS. 6, already described, shows the profile of a pad polished by the technique of FIGS. 4 and 5, 4 and 5,
    • FIG. FIG. 7 shows the general arrangement of the machine of the invention with a stretched microabrasive sheet and a plate support with circular translation, 7 shows the general arrangement of the machine of the invention with a stretched microabrasive sheet and a plate support with circular translation,
    • FIGS. FIGS. 8a and 8b (respectively top view and side view) show a polishing machine according to the invention, 8a and 8b (respectively top view and side view) show a polishing machine according to the invention,
    • FIG. FIG. 9 shows three positions (a, b, c) of the support head and illustrates the distribution of the force exerted, 9 shows three positions (a, b, c) of the support head and illustrates the distribution of the force exerted,
    • FIG. FIG. 10 is a curve showing the variations in the insertion of the plate into the flexible disk as a function of the force exerted on the support head, 10 is a curve showing the variations in the insertion of the plate into the flexible disk as a function of the force exerted on the support head,
    • FIG. FIG. 11 shows, in section, an exemplary embodiment of the support head, 11 shows, in section, an exemplary embodiment of the support head,
    • FIG. FIG. 12 shows a detail of a peripheral ring, 12 shows a detail of a peripheral ring,
    • FIG. FIG. 13 illustrates an embodiment of the peripheral ring, 13 illustrates an embodiment of the peripheral ring,
    • FIG. FIG. 14 shows an intermediate sub-assembly in the production of a magnetic writing and reading head, 14 shows an intermediate sub-assembly in the production of a magnetic writing and reading head,
    • FIG. FIG. 15 shows the profile of this sub-assembly before and after polishing, 15 shows the profile of this sub-assembly before and after polishing,
    • FIG. FIG. 16 shows the completed magnetic head, 16 shows the completed magnetic head,
    • Figure 17 shows the profile of this head before and after polishing. Figure 17 shows the profile of this head before and after polishing.
  • La machine représentée sur la figure 7 comprend schématiquement :
    • un plateau de polissage fixe 30, a fixed polishing plate 30,
    • une tête support d'échantillon 32, comprenant une pièce rigide 140 et un disque de matière souple 142 ayant une certaine épaisseur (e). a sample support head 32, comprising a rigid part 140 and a disc of flexible material 142 having a certain thickness (e). Le diamètre du disque souple est sensiblement le diamètre maximum englobant la zone de la plaquette couverte par les excroissances à polir. The diameter of the flexible disc is substantially the maximum diameter encompassing the area of ​​the wafer covered by the protuberances to be polished. Le disque 142 est fixé sur la pièce rigide 140 et reçoit la plaquette à polir 44. Celle-ci se trouve ainsi enfoncée partiellement dans l'épaisseur du disque 142 en cours de polissage par l'effet de la force exercée sur la tête support ; The disc 142 is fixed to the rigid part 140 and receives the wafer for polishing 44. The latter is thus partially pressed into the thickness of the disc 142 during polishing by the effect of the force exerted on the support head; la matière souple du disque 142 peut être un élastomère, the flexible material of the disc 142 may be an elastomer,
    • des moyens 34 pour exercer une force F sur la tête support 32 afin d'appliquer l'échantillon à polir 44 sur le plateau de polissage 30 et pour déplacer la tête par rapport au plateau, ce moyen pouvant comprendre un excentrique 37. means 34 for exerting a force F on the support head 32 in order to apply the sample to be polished 44 on the polishing plate 30 and to move the head relative to the plate, this means possibly comprising an eccentric 37.
    The machine shown in FIG. The machine shown in FIG. 7 schematically comprises: 7 schematically understood:
    • a fixed polishing plate 30, a fixed polishing plate 30,
    • a sample support head 32, comprising a rigid part 140 and a disk of flexible material 142 having a certain thickness (e). a sample support head 32, comprising a rigid part 140 and a disk of flexible material 142 having a certain thickness (e). The diameter of the flexible disc is substantially the maximum diameter encompassing the area of the wafer covered by the protrusions to be polished. The diameter of the flexible disc is substantially the maximum diameter encompassing the area of ​​the wafer covered by the protrusions to be polished. The disc 142 is fixed on the rigid part 140 and receives the polishing pad 44. This is thus partially pressed into the thickness of the disc 142 during polishing by the effect of the force exerted on the support head; The disc 142 is fixed on the rigid part 140 and receives the polishing pad 44. This is thus partially pressed into the thickness of the disc 142 during polishing by the effect of the force exerted on the support head; the flexible material of the disc 142 may be an elastomer, the flexible material of the disc 142 may be an elastomer,
    • means 34 for exerting a force F on the support head 32 in order to apply the polishing sample 44 to the polishing plate 30 and to move the head relative to the plate, this means possibly comprising an eccentric 37. means 34 for exerting a force F on the support head 32 in order to apply the polishing sample 44 to the polishing plate 30 and to move the head relative to the plate, this means possibly comprising an eccentric 37.
  • Le moyen de polissage comprend une feuille ou bande microabrasive 33 tendue et plaquée sur un plateau de référence 30. La feuille 33 est tendue par des moyens 35, 35′ disposés de part et d'autre du plateau 30.The polishing means comprises a microabrasive sheet or strip 33 stretched and pressed against a reference plate 30. The sheet 33 is stretched by means 35, 35 ′ arranged on either side of the plate 30.
  • Les figures 8a et 8b illustrent un mode particulier de réalisation des moyens 35, 35′ aptes à tendre convenablement la feuille abrasive et à permettre le lent défilement de celle-ci au-dessus du plateau. Sur ces figures, la machine est représentée en vue de dessus sur la partie a et en vue de côté sur la partie b.FIGS. 8a and 8b illustrate a particular embodiment of the means 35, 35 ′ able to tension the abrasive sheet properly and to allow the slow scrolling of it over the board. In these figures, the machine is shown in top view on part a and in side view on part b .
  • Par souci de simplification, la machine représentée ne comprend pas de support de plaquettes à polir, ni d'excentrique, ni de broche rotative, etc. Les figures 8a et 8b s'en tiennent au plateau de référence et aux divers moyens pour tendre sur ce plateau la bande microabrasive et la faire défiler.For the sake of simplification, the machine shown does not include a support for polishing pads, an eccentric, a rotating spindle, etc. FIGS. 8a and 8b stick to the reference plate and to the various means for stretching the microabrasive strip on this plate and making it run.
  • Telle que représentée, la machine comprend une première bobine 40 et une seconde bobine 50 disposées de part et d'autre du plateau de référence 30. Sur ces bobines est enroulée une bande microabrasive 33, laquelle se trouve ainsi tendue entre les deux bobines.As shown, the machine comprises a first coil 40 and a second coil 50 arranged on either side of the reference plate 30. On these coils is wound a microabrasive strip 33, which is thus stretched between the two coils.
  • La première bobine 40 est une bobine débitrice équipée de moyens pour exercer un couple résistant ; la seconde bobine 50 est une bobine réceptrice commandée par un moteur. La bande microabrasive 33 peut ainsi passer de la première bobine 40 à la seconde 50, en défilant au-dessus du plateau de référence 30, ce qui permet le renouvellement de la surface abrasive.The first coil 40 is a supply coil equipped with means for exerting a resistant torque; the second coil 50 is a take-up coil controlled by a motor. The microabrasive strip 33 can thus pass from the first reel 40 to the second 50, while scrolling above the reference plate 30, which allows the renewal of the abrasive surface.
  • Les deux bobines 40, 50 sont disposées sous la face supérieure du plateau de référence 30, deux tambours 41, 51 étant disposés entre les bobines et le plateau de référence 30. La bande microabrasive 33 passe sur ces tambours 41, 51 à la sortie de la bobine débitrice 40 et à l'entrée dans la bobine réceptrice 50. Ces tambours sont de préférence disposés un peu en dessous de la face supérieure du plateau 30 de sorte que la bande microabrasive 33 fait un léger angle ϑ avec l'horizontale à son entrée et sa sortie du plateau, ce qui améliore son contact avec celui-ci.The two coils 40, 50 are arranged under the upper face of the reference plate 30, two drums 41, 51 being arranged between the coils and the reference plate 30. The microabrasive strip 33 passes over these drums 41, 51 at the outlet of the supply reel 40 and at the entry into the take-up reel 50. These drums are preferably arranged a little below the upper face of the plate 30 so that the microabrasive strip 33 makes a slight angle ϑ with the horizontal at its entry and exit of the tray, which improves its contact with it.
  • Dans la variante illustrée, la bobine débitrice 40 est reliée à un bâti 60 par deux paliers à rotules 41, 42 et deux glissières 43, 44 dont les extrémités viennent en appui sur deux capteurs de pression 45, 46 liés au bâti par deux butées réglables 47, 48. Le réglage des butées permet d'équilibrer la tension de la bande sur toute sa largeur.In the illustrated variant, the supply reel 40 is connected to a frame 60 by two ball bearings 41, 42 and two slides 43, 44 whose ends come to bear on two pressure sensors 45, 46 linked to the frame by two adjustable stops 47, 48. The adjustment of the stops makes it possible to balance the tension of the strip over its entire width.
  • Les moyens pour exercer sur la bobine débitrice 40 un couple résistant peuvent être constitués, dans une première variante, par un moteur annulaire 62 monté directement sur l'un des paliers 41 ou 42, en bout de glissière 43. Des moyens 64 de commande de ce moteur sont également prévus. Dans une seconde variante, ces moyens sont constitués par un moteur 66 séparé de la bobine débitrice 40 et par une courroie de transmission 68 entre ce moteur 66 et la bobine débitrice 40. Le brin tendu 68a de la courroie 68 est dans un plan perpendiculaire aux glissières 43, 44. Des moyens 64 de commande de ce moteur sont également prévus.The means for exerting a resistive torque on the supply reel 40 can be constituted, in a first variant, by an annular motor 62 mounted directly on one of the bearings 41 or 42, at the end of the slide 43. Means 64 for controlling the this engine are also provided. In a second variant, these means consist of a motor 66 separate from the supply coil 40 and by a transmission belt 68 between this motor 66 and the supply coil 40. The stretched strand 68a of the belt 68 is in a plane perpendicular to the slides 43, 44. Means 64 for controlling this motor are also provided.
  • Par ailleurs, les deux capteurs de pression 45, 46, disposés aux extrémités des deux glissières 43, 44, sont reliés aux moyens de commande 64 des moteurs 62 ou 66 exerçant un couple résistant sur la bobine débitrice 40.Furthermore, the two pressure sensors 45, 46, arranged at the ends of the two slides 43, 44, are connected to the control means 64 of the motors 62 or 66 exerting a resistant torque on the supply reel 40.
  • De son côté, la bobine réceptrice 50 est commandée en rotation par un motoréducteur 70. Cette bobine peut être reliée au motoréducteur 70 par un moyen 72 d'interruption de la transmission, tel qu'un accouplement mécanique ou un embrayage électro-magnétique.For its part, the take-up reel 50 is controlled in rotation by a geared motor 70. This reel can be connected to the geared motor 70 by a means 72 for interrupting the transmission, such as a mechanical coupling or an electromagnetic clutch.
  • On va décrire maintenant plus en détail la structure et les fonctions de la tête support d'échantillon qui coopère avec la bande microabrasive tendue pour permettre un polissage dans les conditions exposées plus haut. We will now describe in more detail the structure and functions of the sample support head which cooperates with the stretched microabrasive strip. to allow polishing under the conditions set out above.
  • Comme représenté sur la figure 7, la tête porte-échantillon comprend un disque souple 142 dont le rôle est illustré sur la figure 9. As shown in FIG. 7, the sample-holder head comprises a flexible disc 142 whose role is illustrated in FIG. 9.
  • Sur cette figure, on voit, sur la partie a, la tête support dégagée de la plaquette à polir 144, laquelle a été représentée avec une déformation très exagérée pour bien montrer les fonctions qui vont être remplies par le disque souple 142. Les reliefs à polir sont référencéss 143.In this figure, we see, on part a , the support head released from the polishing pad 144, which has been shown with a very exaggerated deformation to clearly show the functions which will be fulfilled by the flexible disc 142. The reliefs to polish are referenced 143.
  • La force F appliquée verticalement sur la pièce rigide 140 a pour effet de plaquer l'ensemble sur le plan de polissage 130, les motifs en relief 143 venant prendre appui sur ce plan (partie b). Cependant, du fait de la déformation initiale de la plaquette, la force d'appui de ces reliefs sur le plan de polissage 130 est inégalement répartie : on a ainsi des forces F1, en périphérie, relativement grandes et des forces F2, au centre, relativement faibles dans l'exemple illustré.The force F applied vertically on the rigid part 140 has the effect of pressing the assembly on the polishing plane 130, the raised patterns 143 coming to bear on this plane (part b ). However, due to the initial deformation of the plate, the bearing force of these reliefs on the polishing plane 130 is unevenly distributed: thus forces F1, at the periphery, relatively large and forces F2, at the center, relatively weak in the example illustrated.
  • L'application d'une force plus grande sur la partie rigide 140 a pour effet de faire pénétrer la plaquette 144 dans le disque souple 142 (partie c). L'enfoncement épouse la déformation initiale de la plaquette et permet de compenser celle-ci. La force F3 exercée par chaque relief sur le plan de polissage est alors sensiblement la même sur toute la surface du plan de polissage.The application of a greater force on the rigid part 140 has the effect of causing the wafer 144 to penetrate into the flexible disc 142 (part c ). The depression conforms to the initial deformation of the insert and makes it possible to compensate for the latter. The force F3 exerted by each relief on the polishing plane is then substantially the same over the entire surface of the polishing plane.
  • Dans ces conditions, on comprend que l'effort exercé sur la plaquette remplit deux fonctions :
    • amener la face principale de la plaquette à épouser la géométrie du plan de réfé rence, quelle que soit la déformation initiale et les défauts d'épaisseur de la plaquette, bring the main face of the insert to match the geometry of the reference plane, regardless of the initial deformation and the thickness defects of the insert,
    • obtenir sur chaque excroissance une pression suffisante pour que l'enlèvement de matière soit effectif et optimum pour une vitesse de déplacement donnée. obtain sufficient pressure on each protuberance for material removal to be effective and optimum for a given displacement speed.
    Under these conditions, we understand that the force exerted on the wafer fulfills two functions: Under these conditions, we understand that the force exerted on the wafer fulfills two functions:
    • bring the main face of the wafer to match the geometry of the reference plane, whatever the initial deformation and the thickness defects of the brochure, bring the main face of the wafer to match the geometry of the reference plane, whatever the initial deformation and the thickness defects of the brochure,
    • obtain sufficient pressure on each protuberance for the removal of material to be effective and optimum for a given speed of movement. obtain sufficient pressure on each protuberance for the removal of material to be effective and optimum for a given speed of movement.
  • Une fois la plaquette appliquée sur le film microabrasif, on déplace le support par rapport au plan de rodage, selon une translation circulaire (rotation du centre de la plaque autour d'un point situé dans le plan de rodage, la plaquette gardant toujours la même orientation). Ainsi, chaque excroissance a une même vitesse linéaire, quelle que soit sa position sur la plaque.Once the wafer has been applied to the microabrasive film, the support is moved relative to the running-in plane, in a circular translation (rotation of the center of the wafer around a point in the running-in plane, the wafer always keeping the same orientation). Thus, each protuberance has the same linear speed, whatever its position on the plate.
  • Dans la configuration décrite précédemment, chaque excroissance reçoit une charge proportionnelle à sa hauteur. Puis, après nivelage partiel, toutes les excroissances reçoivent une charge identique. On peut alors considérer que le contact est correct au niveau de chaque dépassement. Par contre, lorsque la hauteur des dépassements diminue, la distance séparant le plan principal de la plaquette et le plan de rodage diminue ; comme le contact entre deux plans n'est jamais parfait, les phénomènes dus à la viscosité de l'air apparaissent et ont tendance à provoquer un décollement partiel de la plaque. Aussi doit-on diminuer la vitesse de déplacement et/ou augmenter la pression exercée sur le support de la plaquette.In the configuration described above, each projection receives a load proportional to its height. Then, after partial leveling, all the growths receive an identical load. We can then consider that the contact is correct at each overshoot. On the other hand, when the height of the overhangs decreases, the distance separating the main plane of the insert and the running-in plane decreases; as the contact between two planes is never perfect, phenomena due to the viscosity of the air appear and tend to cause partial separation of the plate. So we must decrease the speed of movement and / or increase the pressure on the support of the wafer.
  • L'enlèvement de matière selon l'invention exclut l'usage de tout liquide de refroidissement ou de drainage de particules. Le travail s'effectue donc "à sec". Si nécessaire, on peut faire le vide dans la zone de travail ou remplacer l'air par un gaz léger comme l'hélium.The removal of material according to the invention excludes the use of any coolant or particle drainage. The work is therefore carried out "dry". If necessary, a vacuum can be created in the work area or the air can be replaced by a light gas such as helium.
  • La détermination des caractéristiques du disque souple à employer selon l'invention passe d'abord par celle de l'effort Po minimum à exercer sur la plaquette pour amener la géométrie de la face avant à épouser le plan de référence.Determining the characteristics of the flexible disk to be used according to the invention first passes through that of the minimum force Po to be exerted on the wafer to bring the geometry of the front face to match the reference plane.
  • Dans le cas d'une déformation homogène de la plaquette en forme de calotte sphérique, il s'agit de faire fléchir la plaquette de telle sorte que la contrainte issue de la force annule la flèche "f". In the case of a homogeneous deformation of the plate in the form of a spherical cap, it is a question of making the plate bend so that the stress resulting from the force cancels the arrow "f".
  • Les lois de la résistance des matériaux donnent pour Po : Po = (3πE e³f)/5 r²
    Figure imgb0001
    où :
    Les lois de la résistance des matériaux donnent pour Po : Po = (3πE e³f)/5 r²
    Figure imgb0001
    où :
    Les lois de la résistance des matériaux donnent pour Po : Po = (3πE e³f)/5 r²
    Figure imgb0001
    où :
    Les lois de la résistance des matériaux donnent pour Po : Po = (3πE e³f)/5 r²
    Figure imgb0001
    où :
    • E est le module d'élasticité (ou module de YOUNG) du matériau constituant la plaquette, E is the modulus of elasticity (or YOUNG's modulus) of the material constituting the plate,
    • Po est une charge ponctuelle appliquée au centre de la plaquette (sommet du bombé), la plaquette étant en appui sur sa circonférence, Po is a point load applied to the center of the plate (crown of the crown), the plate resting on its circumference,
    • e est l'épaisseur moyenne de la plaquette, e is the average thickness of the wafer,
    • r est le rayon de la plaquette. r is the radius of the wafer.
    The laws of resistance of materials give for Po: The laws of resistance of materials give for Po: Po = (3πE e³f) / 5 r² Po = (3πE e³f) / 5 r²
    Figure imgb0001
    or : gold :
    • E is the elastic modulus (or YOUNG modulus) of the material constituting the wafer, E is the elastic modulus (or YOUNG modulus) of the material constituting the wafer,
    • Po is a point load applied to the center of the plate (top of the crown), the plate being supported on its circumference, Po is a point load applied to the center of the plate (top of the crown), the plate being supported on its circumference,
    • e is the average thickness of the wafer, e is the average thickness of the wafer,
    • r is the radius of the insert. r is the radius of the insert.
  • Cette charge Po appliquée à la plaquette sera répartie de façon totalement hétérogène. En effet, cette charge sera concentrée au milieu, les bords de la plaquette venant à peine au contact du plan de référence sans transmission d'efforts. This load Po applied to the wafer will be distributed in a completely heterogeneous manner. Indeed, this load will be concentrated in the middle, the edges of the plate barely coming into contact with the reference plane without transmission of forces.
  • Dans le cas de déformations complexes, une bonne approximation consiste à prendre en compte le relief le plus difficile à amener au contact du plan de référence, en utilisant la formule précédente. Cette détermination revient à comparer les rapports f/r² dans une zone de rayon "r" affectée par cette flèche. Une fois le rapport maximum déterminé, on ramène l'effort nécessaire pour récupérer cette déformation à l'ensemble de la surface du disque souple.In the case of complex deformations, a good approximation consists in taking into account the most difficult relief to bring into contact with the reference plane, by using the preceding formula. This determination amounts to comparing the ratios f / r² in an area of radius "r" affected by this arrow. Once the maximum ratio has been determined, the effort necessary to recover this deformation is reduced to the entire surface of the flexible disk.
  • Il s'agit ensuite de déterminer l'écart de répartition d'effort admissible. C'est un compromis entre l'homogénéité maximum et la valeur maximum de pression admissible par l'abrasif, pour des reliefs donnés (risque de détérioration de la surface abrasive ou des reliefs). On considère en général que 5 à 10% d'écart sont acceptables. On prendra comme effort maximum une valeur P1 égale à 10 à 20 fois la valeur Po calculée comme indiqué plus haut.It is then a matter of determining the difference in the distribution of admissible effort. It is a compromise between maximum homogeneity and the maximum value of admissible pressure by the abrasive, for given reliefs (risk of deterioration of the abrasive surface or reliefs). It is generally considered that 5 to 10% difference is acceptable. We will take as maximum effort a value P1 equal to 10 to 20 times the value Po calculated as indicated above.
  • Enfin seulement, on peut déterminer les caractéristiques du disque. La courbe de la figure 10 montre l'enfoncement (en ordonnées) en fonction de la pression (en abscisses), la charge étant supposée répartie sur une surface unitaire.Finally only, we can determine the characteristics of the disc. The curve in FIG. 10 shows the depression (on the ordinate) as a function of the pressure (on the abscissa), the load being assumed to be distributed over a unit surface.
  • La droite A ne tient pas compte de l'épaisseur finie du disque (autrement dit elle suppose une épaisseur infinie). La courbe B tient compte de cette épaisseur. Une épaisseur finie conduit à un "talonnement" du matériau constituant le disque (en général un élastomère).Line A does not take into account the finite thickness of the disc (in other words, it assumes an infinite thickness). Curve B takes this thickness into account. A finite thickness leads to a "hooking" of the material constituting the disc (in general an elastomer).
  • La charge P1 donne la valeur de la pression sur la surface unitaire choisie pour tracer la courbe. On reporte cette valeur sur la courbe pour obtenir la flèche correspondante soit "f1". The load P1 gives the value of the pressure on the unit surface chosen to draw the curve. This value is plotted on the curve to obtain the corresponding arrow, ie "f1".
  • L'enfoncement du matériau souple est variable selon l'épaisseur de la plaquette. La charge P1 conduit à une pression locale proportionnelle à l'épaisseur de la plaque en un point donné. The penetration of the flexible material is variable depending on the thickness of the wafer. The load P1 leads to a local pressure proportional to the thickness of the plate at a given point.
  • On reporte sur l'axe des ordonnées la valeur de l'écart maximum sur l'épaisseur des plaques, Δ e en le centrant sur f1. On obtient ainsi la variation ΔP1 maximum due à l'écart Δe autour de P1. The value of the maximum difference over the thickness of the plates, Δ e is transferred to the ordinate axis by centering it on f1. This gives the maximum variation ΔP1 due to the difference Δe around P1.
  • On vérifie alors que P1 reste compatible avec les 5 à 10% d'homogénéité choisis. It is then verified that P1 remains compatible with the 5 to 10% homogeneity chosen.
  • Si cette valeur est dépassée, on peut :
    • augmenter l'épaisseur du disque souple, si on se trouve proche de la zone horizontale de la courbe, increase the thickness of the flexible disc, if it is close to the horizontal zone of the curve,
    • augmenter sa souplesse et donc rechercher une nouvelle courbe, si l'on se trouve déjà loin du talonnement. increase your flexibility and therefore seek a new curve, if you are already far from bottoming out.
    If this value is exceeded, we can: If this value is exceeded, we can:
    • increase the thickness of the flexible disk, if you are close to the horizontal zone of the curve, increase the thickness of the flexible disk, if you are close to the horizontal zone of the curve,
    • increase its flexibility and therefore look for a new curve, if you are already far from the tailgating. increase its flexibility and therefore look for a new curve, if you are already far from the tailgating.
  • On peut observer qu'il n'est pas souhaitable de travailler dans le bas de la courbe, le contact entre disque souple et plaque n'étant pas garanti en tous points. We can observe that it is not desirable to work at the bottom of the curve, the contact between flexible disk and plate is not guaranteed in all points.
  • Les variations d'enfoncement du disque souple peuvent avoir d'autres origines :
    • épaisseur variable du disque souple ; variable thickness of the flexible disc;
    • mauvaise planéité du support sur lequel est collé le disque ; poor flatness of the support on which the disc is glued;
    • mauvais collage du disque sur son support. bad gluing of the disc on its support.
    Variations in the insertion of the flexible disc can have other origins: Variations in the insertion of the flexible disc can have other origins:
    • variable thickness of the flexible disk; variable thickness of the flexible disk;
    • poor flatness of the support on which the disc is stuck; poor flatness of the support on which the disc is stuck;
    • bad bonding of the disc on its support. bad bonding of the disc on its support.
  • Ces écarts doivent être maintenus dans la limite des 5 à 10% déjà pris en compte. These differences must be kept within the limit of 5 to 10% already taken into account.
  • Les mécanismes évoqués plus haut à propos de la détermination de la pression minimum et du support souple, interviennent dans le rôle régulateur du disque souple. En effet, si les excroissances à niveler présentent des hauteurs variables, ce sont les plus hautes qui, dans un premier temps, recevront la plus grande partie de l'effort P1. La plaque subira dans cette zone une flèche qui sera compensée au niveau de la matière souple, par un enfoncement supplémentaire, ce qui se traduira par une augmentation de la pression dans cette zone. Le point sera donc rodé plus rapidement que les autres.The mechanisms mentioned above regarding the determination of the minimum pressure and the flexible support, intervene in the regulating role of the flexible disc. In fact, if the growths to be leveled have variable heights, it is the tallest ones which will initially receive the greatest part of the force P1. The plate will undergo an arrow in this zone which will be compensated at the level of the flexible material, by an additional depression, which will result in an increase in the pressure in this zone. The point will therefore be broken in more quickly than the others.
  • Différents modes de réalisation du support de plaquettes vont maintenant être décrits en liaison avec les figures 11 à 13.Different embodiments of the wafer support will now be described in conjunction with FIGS. 11 to 13.
  • Le support représenté sur la figure 11, tout d'abord, comprend un corps rigide en deux parties 150-152 sur lequel le disque souple 142 vient prendre appui, et un dispositif 158 permettant trois rotations selon trois axes perpendiculaires, deux de ces rotations, utilisées pour positionner et orienter correctement la plaquette 44 sur le plan de référence, pouvant être partielles (ou d'amplitude limitée), la troisième étant complète suivant un axe perpendiculaire au plan de référence. Le dispositif 158 permet la liaison avec un axe vertical 160. Ce dispositif est de préférence un roulement à rotule ou un roulement à aiguilles associé à une rotule. Le corps rigide 150 est entouré d'un anneau périphérique 162 dans lequel un décrochement 163 a été usiné. La hauteur du décrochement 163 est inférieure à l'épaisseur de la plaquette et son diamètre est légèrement supérieur à celui de la plaquette. La plaquette 44 vient prendre appui dans ce décrochement 163. La pièce en anneau 162 est reliée au corps rigide 150 par des colonnettes 164 et des ressorts 166.The support shown in Figure 11, first of all, comprises a rigid body in two parts 150-152 on which the flexible disc 142 comes to take support, and a device 158 allowing three rotations along three perpendicular axes, two of these rotations, used to correctly position and orient the wafer 44 on the reference plane, which may be partial (or of limited amplitude), the third being complete according to an axis perpendicular to the reference plane. The device 158 allows the connection with a vertical axis 160. This device is preferably a spherical bearing or a needle bearing associated with a spherical bearing. The rigid body 150 is surrounded by a peripheral ring 162 in which a recess 163 has been machined. The height of the step 163 is less than the thickness of the plate and its diameter is slightly greater than that of the plate. The plate 44 comes to bear in this recess 163. The ring piece 162 is connected to the rigid body 150 by posts 164 and springs 166.
  • L'effort vertical appliqué sur l'axe 160 ne passe pas par l'anneau périphérique 162 mais par la rotule 158, le corps rigide 150 et le disque 142. L'anneau 162 ne sert qu'à entraîner la plaquette 44 dans le mouvement de translation circulaire nécessaire au polissage, mouvement produit par la force horizontale d'entraînement du support (produit par exemple par l'excentrique 37 de la figure 7).The vertical force applied to the axis 160 does not pass through the peripheral ring 162 but through the ball joint 158, the rigid body 150 and the disc 142. The ring 162 only serves to drive the plate 44 in the movement of circular translation necessary for polishing, movement produced by the horizontal force driving the support (produced for example by the eccentric 37 in FIG. 7).
  • Le corps rigide 150-152 est percé d'un canal 170 relié par une tubulure 172 à une machine à vide non représentée. Cette disposition permet de maintenir en place la plaquette 44 pendant les phases où le support n'est pas plaqué sur le plan de polissage.The rigid body 150-152 is pierced with a channel 170 connected by a tube 172 to a vacuum machine not shown. This arrangement keeps the wafer 44 in place during the phases where the support is not pressed against the polishing plane.
  • La figure 12 montre un détail de l'anneau périphérique 162, avec son décrochement 163 recevant la plaquette 44. Dans la variante illustrée, c'est l'anneau 162, auquel on ajoute une rainure circulaire 161, qui est percé d'un canal 174 relié par une tubulure 176 très souple à une machine à vide non représentée. Cette variante correspond à des polissages nécessitant des efforts de couple plus importants que dans le cas de la figure 11.FIG. 12 shows a detail of the peripheral ring 162, with its recess 163 receiving the plate 44. In the illustrated variant, it is the ring 162, to which a circular groove 161 is added, which is pierced with a channel 174 connected by a tube 176 very flexible to a vacuum machine not shown. This variant corresponds to polishing requiring greater torque forces than in the case of FIG. 11.
  • Dans la variante illustrée sur la figure 13, l'anneau périphérique est constitué par un anneau mince 180 taillé par exemple dans une feuille d'acier, cet anneau mince étant rigide dans son plan mais souple dans la direction perpendiculaire. Cet anneau mince 180 est enrobé dans une matière très souple 182, par exemple en silicone. Une telle pièce annulaire est suffisamment rigide dans le plan horizontal pour transmettre les efforts de coupe, tout en étant suffisamment souple verticalement pour épouser les défauts de la plaquette.In the variant illustrated in FIG. 13, the peripheral ring consists of a thin ring 180 cut for example from a steel sheet, this thin ring being rigid in its plane but flexible in the perpendicular direction. This thin ring 180 is coated in a very flexible material 182, for example silicone. Such an annular part is sufficiently rigid in the horizontal plane to transmit the cutting forces, while being flexible enough vertically to match the defects of the insert.
  • Avec la machine de polissage qui vient d'être décrite, le Demandeur a obtenu des résultats remarquables illustrés sur les figures 14 à 17.With the polishing machine which has just been described, the Applicant has obtained remarkable results illustrated in FIGS. 14 to 17.
  • La figure 14 montre, en coupe, un sous-ensemble correspondant à une tête magnétique d'écriture et de lecture en structure horizontale, du genre de celle qui a été déjà évoquée à propos de la figure 1. Le sous-ensemble de la figure 14 comprend essentiellement un substrat en silicium 100, deux bords de caisson 102 en silice, deux plots verticaux 104 en fer-nickel. Il s'agit de polir ce sous-ensemble selon un plan 106 avant de poursuivre les opérations de formation de la pièce polaire supérieure.FIG. 14 shows, in section, a sub-assembly corresponding to a magnetic writing and reading head in a horizontal structure, of the kind which has already been mentioned in connection with FIG. 1. The sub-assembly of FIG. 14 essentially comprises a silicon substrate 100, two edges of the casing 102 in silica, two vertical pads 104 in iron-nickel. This involves polishing this sub-assembly according to a plane 106 before continuing the operations of forming the upper pole piece.
  • Avant polissage, le profil du sous-ensemble est représenté sur la partie a de la figure 15. En abscisses, la totalité de l'intervalle relevé mesure 1,2 mm (les unités indiquées sont donc en micromètres). En ordonnées, les unités sont en centaines de nanomètres. On voit nettement, sur ce relevé, les deux bords du caisson et, au centre, les deux plots verticaux en fer-nickel.Before polishing, the profile of the sub-assembly is shown in part a of Figure 15. In abscissa, the entire recorded interval measures 1.2 mm (the units indicated are therefore in micrometers). On the ordinate, the units are in hundreds of nanometers. We can clearly see, on this statement, the two edges of the box and, in the center, the two vertical iron-nickel studs.
  • Après polissage, le profil présente la forme de la partie b de la figure 15. La totalité de l'intervalle relevé mesure 4 mm (ce qui signifie que le relevé porte sur la totalité du "ski" portant la tête). En ordonnées, l'échelle est en dizaines de nanomètres. Le dépassement résiduel dans la courbure naturelle du "ski" est inférieur ou égal à 30 nm (cette courbure étant une fraction de la déformation du substrat).After polishing, the profile has the shape of part b of FIG. 15. The whole of the recorded interval measures 4 mm (which means that the statement relates to the entire "ski" carrying the head). On the ordinate, the scale is in tens of nanometers. The residual overshoot in the natural curvature of the "ski" is less than or equal to 30 nm (this curvature being a fraction of the deformation of the substrate).
  • La figure 16 montre la tête après les opérations de formation de l'espaceur amagnétique 110 et des pièces polaires supérieures 112 en fer-nickel. Des reliefs 114 apparaissent au centre de la tête. Le plan final de polissage est référencé 116.FIG. 16 shows the head after the operations for forming the non-magnetic spacer 110 and the upper pole pieces 112 made of iron-nickel. Reliefs 114 appear in the center of the head. The final polishing plan is referenced 116.
  • Sur la partie a de la figure 17, on voit le profil de ce sous-ensemble avant rodage. Les unités sont les mêmes que pour la figure 15a : 1,2 mm pour la totalité de l'axe des abscisses et centaines de nanomètres en ordonnées. Les trois pics correspondants aux trois reliefs des pièces polaires sont bien visibles.On part a of FIG. 17, we see the profile of this sub-assembly before running in. The units are the same as for FIG. 15a: 1.2 mm for the entire abscissa axis and hundreds of nanometers on the ordinate. The three peaks corresponding to the three reliefs of the pole pieces are clearly visible.
  • La partie b de la figure 17 montre le relevé après polissage. En abscisses, les unités sont encore en micromètres et en ordonnées, en dizaines de nanométres. Aucun dépassement résiduel n'est détecté, on ne mesure que la courbure naturelle du patin (cette courbure étant une fraction de la déformation du substrat).Part b of Figure 17 shows the reading after polishing. On the abscissa, the units are still in micrometers and on the ordinate, in tens of nanometers. No residual overshoot is detected, we only measure the natural curvature of the pad (this curvature being a fraction of the deformation of the substrate).

Claims (13)

  1. Polishing machine comprising:
    - a taut microabrasive strip (33) above a disk between a delivery roll and a receiving roll,
    - a support head able to keep a sample (44) to be polished with the face to be polished facing the abrasive strip,
    - a delivery roll (40) equipped with means (62, 66) for exerting thereon a resistant torque and a receiving roll (50) controlled by a motor,
    characterized in that:
    - the disk offers a rigid, planar upper face,
    - the sample support head (32) comprises a rigid part (40) and a disk (42) made from a flexible material and having a certain thickness, said disk being fixed to said rigid part (40) and receives the wafer (44) to be polished, the rigid part (40) being connected by a self-aligning bearing (58) and a vertical shaft (60) to means (34) for displacing the support head (32) in a circular translatory movement.
  2. Machine according to claim 1, characterized in that the delivery roll (40) is connected to a frame (60) by two swivel bearings (41, 42) and two slides (43, 44), whose ends bear on two pressure transducers (45, 46) connected to the frame by two regulatable abutments (47, 48), the regulation of the abutments making it possible to balance the tension of the strip over its entire width.
  3. Machine according to claim 2, characterized in that the means for exerting a resistant torque on the delivery roll (40) are constituted by an annular motor (62) directly mounted on one of the swivel bearings (41, 42), at the end of the slide (43), and by motor control means (64).
  4. Machine according to claim 2, characterized in that the means for exerting a resistant torque on the delivery roll (40) are constituted by a motor (66) separate from said roll (40) and by a transmission bell (68) between the said motor (66) and the delivery roll (40), said bell having a taut side (68a) in a plane perpendicular to the slides (43, 44) and by motor control means (64).
  5. Machine according to claims 3 or 4, characterized in that the two pressure transducers (45, 46) located at the ends of the two slides (43, 44) are connected to the control means (64) of the motor (62, 66) exerting a resistant torque on the delivery roll (40).
  6. Machine according to claim 1, characterized in that the receiving roll (50) is control led in rotation by a geared motor (70).
  7. Machine according to claim 6, characterized in that the receiving roll (50) is connected to the geared motor (70) by a transmission interruption means (72), such as a mechanical coupling or an electromagnetic clutch.
  8. Machine according to claim 1, characterized in that the delivery roll (40) and the receiving roll (50) are positioned below the upper face of the reference disk (30), two drums (41, 51) being plated between the rolls and the reference disk (30), the microabrasive strips (33) passing on said drums (41, 51) on leaving the delivery roll (40) and on entering the receiving roll (50).
  9. Machine according to claim 8, characterized in that the two drums (41, 51) are placed below the upper face of the reference disk (30) , the microabrasive strip (33) on entering and leaving the disk forming an angle (ϑ) relative to the horizontal.
  10. Machine according to claim 1, characterized in that the rigid part (150-152) of the support head is surrounded by a peripheral ring (162) having a groove (163) with a diameter slightly exceeding the diameter of the wafer (44) and whose height is slightly less than the thickness of the wafer (44), which then bears in the groove (163), said ring (162) being connected to the rigid part (150) of the wafer support by means (164) able to transmit to the ring (162) and therefore to the wafer (44), forces linked with the transverse displacement of the support head relative to the microabrasive film, the pressure exerted on the support head being transmitted to the wafer by the rigid part (150-152) and the flexible material disk (142).
  11. Machine according to claim 10, characterized in that the peripheral ring (162) is constituted by a planar thin ring (180), which is rigid in its plane, but flexible perpendicular to said plane and is flexibly moulded (182) around said thin ring (180).
  12. Machine according to claim 1, characterized in that the rigid part (150) of the support head is perforated by a channel (170) also traversing the flexible material disk (142), said channel (170) being connected by a tube (172) to a vacuumizing machine.
  13. Machine according to claim 10, characterized in that the peripheral ring (162) is perforated by a channel (174) issuing into the groove (163) where the wafer (44) bears, said channel (174) being connected to a vacuumizing machine by a flexible tube (176).
EP19920401532 1991-06-06 1992-06-04 Polishing machine with a tensioned finishing belt and an improved work supporting head Expired - Lifetime EP0517594B1 (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
FR9106866 1991-06-06
FR9106866A FR2677288B1 (en) 1991-06-06 1991-06-06 POLISHING MACHINE WITH TENSIONED MICROBRASIVE SHEET.
FR9106869A FR2677293A1 (en) 1991-06-06 1991-06-06 Polishing machine with improved wafer-support head
FR9106869 1991-06-06

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EP0517594A1 (en) 1992-12-09
DE69206685T2 (en) 1996-07-04
DE69206685D1 (en) 1996-01-25
JPH05177523A (en) 1993-07-20
US5335453A (en) 1994-08-09

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