EP4121821A1 - Method for manufacturing a silicon-based timepiece component - Google Patents

Method for manufacturing a silicon-based timepiece component

Info

Publication number
EP4121821A1
EP4121821A1 EP21712581.4A EP21712581A EP4121821A1 EP 4121821 A1 EP4121821 A1 EP 4121821A1 EP 21712581 A EP21712581 A EP 21712581A EP 4121821 A1 EP4121821 A1 EP 4121821A1
Authority
EP
European Patent Office
Prior art keywords
silicon
etching
thermal oxidation
deoxidation
component
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21712581.4A
Other languages
German (de)
French (fr)
Inventor
Jean-Luc Bucaille
Sylvain Jeanneret
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Patek Philippe SA Geneve
Original Assignee
Patek Philippe SA Geneve
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Patek Philippe SA Geneve filed Critical Patek Philippe SA Geneve
Publication of EP4121821A1 publication Critical patent/EP4121821A1/en
Pending legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B31/00—Bearings; Point suspensions or counter-point suspensions; Pivot bearings; Single parts therefor
    • G04B31/06—Manufacture or mounting processes
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B29/00—Frameworks
    • G04B29/02—Plates; Bridges; Cocks
    • G04B29/027—Materials and manufacturing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F1/00—Originals for photomechanical production of textured or patterned surfaces, e.g., masks, photo-masks, reticles; Mask blanks or pellicles therefor; Containers specially adapted therefor; Preparation thereof
    • G03F1/68—Preparation processes not covered by groups G03F1/20 - G03F1/50
    • G03F1/80—Etching
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/075—Silicon-containing compounds
    • G03F7/0755—Non-macromolecular compounds containing Si-O, Si-C or Si-N bonds
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/20—Exposure; Apparatus therefor
    • G03F7/2002—Exposure; Apparatus therefor with visible light or UV light, through an original having an opaque pattern on a transparent support, e.g. film printing, projection printing; by reflection of visible or UV light from an original such as a printed image
    • G03F7/2014—Contact or film exposure of light sensitive plates such as lithographic plates or circuit boards, e.g. in a vacuum frame
    • G03F7/2016—Contact mask being integral part of the photosensitive element and subject to destructive removal during post-exposure processing
    • G03F7/202—Masking pattern being obtained by thermal means, e.g. laser ablation
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B11/00—Click devices; Stop clicks; Clutches
    • G04B11/02—Devices allowing the motion of a rotatable part in only one direction
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B13/00—Gearwork
    • G04B13/02—Wheels; Pinions; Spindles; Pivots
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B15/00—Escapements
    • G04B15/14—Component parts or constructional details, e.g. construction of the lever or the escape wheel
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/04—Oscillators acting by spring tension
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/04—Oscillators acting by spring tension
    • G04B17/06—Oscillators with hairsprings, e.g. balance
    • G04B17/063—Balance construction
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/04—Oscillators acting by spring tension
    • G04B17/06—Oscillators with hairsprings, e.g. balance
    • G04B17/066—Manufacture of the spiral spring
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/20—Compensation of mechanisms for stabilising frequency
    • G04B17/22—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature
    • G04B17/222—Compensation of mechanisms for stabilising frequency for the effect of variations of temperature with balances
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/32—Component parts or constructional details, e.g. collet, stud, virole or piton
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B17/00—Mechanisms for stabilising frequency
    • G04B17/32—Component parts or constructional details, e.g. collet, stud, virole or piton
    • G04B17/34—Component parts or constructional details, e.g. collet, stud, virole or piton for fastening the hairspring onto the balance
    • G04B17/345—Details of the spiral roll
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B19/00—Indicating the time by visual means
    • G04B19/04—Hands; Discs with a single mark or the like
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B19/00—Indicating the time by visual means
    • G04B19/04—Hands; Discs with a single mark or the like
    • G04B19/042—Construction and manufacture of the hands; arrangements for increasing reading accuracy
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B19/00—Indicating the time by visual means
    • G04B19/06—Dials
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B19/00—Indicating the time by visual means
    • G04B19/06—Dials
    • G04B19/12—Selection of materials for dials or graduations markings
    • G—PHYSICS
    • G04—HOROLOGY
    • G04B—MECHANICALLY-DRIVEN CLOCKS OR WATCHES; MECHANICAL PARTS OF CLOCKS OR WATCHES IN GENERAL; TIME PIECES USING THE POSITION OF THE SUN, MOON OR STARS
    • G04B21/00—Indicating the time by acoustic means
    • G04B21/02—Regular striking mechanisms giving the full hour, half hour or quarter hour
    • G04B21/06—Details of striking mechanisms, e.g. hammer, fan governor
    • G—PHYSICS
    • G04—HOROLOGY
    • G04D—APPARATUS OR TOOLS SPECIALLY DESIGNED FOR MAKING OR MAINTAINING CLOCKS OR WATCHES
    • G04D3/00—Watchmakers' or watch-repairers' machines or tools for working materials
    • G04D3/0069—Watchmakers' or watch-repairers' machines or tools for working materials for working with non-mechanical means, e.g. chemical, electrochemical, metallising, vapourising; with electron beams, laser beams
    • G—PHYSICS
    • G04—HOROLOGY
    • G04F—TIME-INTERVAL MEASURING
    • G04F7/00—Apparatus for measuring unknown time intervals by non-electric means
    • G04F7/04—Apparatus for measuring unknown time intervals by non-electric means using a mechanical oscillator
    • G04F7/08—Watches or clocks with stop devices, e.g. chronograph
    • G04F7/0804—Watches or clocks with stop devices, e.g. chronograph with reset mechanisms

Definitions

  • the present invention relates to a method of manufacturing a silicon-based horological component, in particular for a wristwatch or pocket watch.
  • Silicon is a material highly valued in mechanical watchmaking for its advantageous properties, in particular its low density, its high resistance to corrosion, its non-magnetic nature and its ability to be machined by micro-manufacturing techniques. It is thus used to manufacture spiral springs, balances, flexibly guided oscillators, escapement anchors and escapement wheels.
  • Silicon nevertheless has the drawback of low mechanical strength, a drawback which is aggravated by the etching method generally used for its machining, deep reactive ionic etching known as DRIE, which leaves sharp edges and creates shape flatness defects. wavelets (called “scalloping" in English) on the sides of the room.
  • This low mechanical strength is problematic for the handling of the components during their assembly in a movement or in the event of shocks undergone by the watch.
  • the components can indeed easily break.
  • the watch components made of silicon are generally reinforced by a coating of silicon oxide with a thickness much greater than that of the native oxide, as described in patent application WO 2007/000271. This coating is generally left on the final component but, according to the teaching of patent application EP 2277822, it can be removed without significantly affecting the mechanical strength.
  • the mechanical strength must also be sufficient for the component to be able to deform elastically without breaking during its operation in order to perform its function.
  • the operating stresses are relatively low, of the order of a few hundred MPa at most, so that the mechanical strength provided by the silicon oxide layer may in theory be sufficient.
  • the oscillation frequencies in operation (4 Hz, 10 Hz or even 50 Hz)
  • the number of cycles is high, which can lead to risks of rupture by fatigue.
  • the Applicant's patent application WO 2019/202378 it is possible to produce silicon watch springs capable of withstanding particularly high stresses and also exhibiting great resistance to fatigue.
  • the method described in this patent application comprises a succession of steps which considerably improves the quality of the silicon springs, in particular the surface condition and the rounding of the edges, which results in an average breaking stress close to 5.
  • GPa the springs are successively thermally oxidized, deoxidized, subjected to an annealing operation in a reducing atmosphere and covered with a layer of silicon oxide, the annealing operation possibly being carried out before the thermal oxidation as a variant.
  • this process has drawbacks: the annealing step is expensive to implement and requires the use of a bulky machine.
  • the present invention aims to remedy these drawbacks and more generally to allow the manufacture, at moderate cost, of a spring or other watch component having high mechanical strength.
  • a method is proposed for manufacturing a watch component according to which a part having the desired shape of the watch component is produced on a silicon basis and the part is subjected to a thermal oxidation and deoxidation treatment in order to remove a predetermined thickness of silicon in order to increase the mechanical strength of the part, characterized in that said treatment is carried out in several stages, each stage comprising a thermal oxidation phase followed by a deoxidation phase.
  • the silicon oxide layer that appears on its surface is formed by consuming silicon to a depth corresponding to 44% of its thickness. After removing the silicon oxide layer, there is therefore a silicon part of reduced size, whose surface defects (wavelets, cracks, gaps, etc.) constituting the initiators of fracture have been attenuated or even eliminated.
  • the thermal oxidation and deoxidation treatment of the method according to the invention can be followed by steps aimed at adjusting the stiffness or the frequency of the component by one or more sequences.
  • oxidation - deoxidation each preceded by a step of measuring the stiffness or the frequency and by a step of calculating the thickness of silicon to be removed, as described for example in documents EP 3181938 and EP 3416001.
  • the adjustment of the stiffness or the frequency can alternatively be carried out before the thermal oxidation and deoxidation treatment according to the invention.
  • a final layer on the part for example a layer of silicon oxide, a layer improving tribological properties, a layer forming a barrier against oxygen. or a layer serving to contain any debris, even if, as regards the silicon oxide layer, this is made superfluous by the repetition of the thermal oxidation and deoxidation phases, as will be demonstrated in the following.
  • FIG. 1 is a diagram showing the different steps of a manufacturing process according to a particular embodiment of the invention
  • FIG. 2 and 3 are graphs showing by boxplots the apparent breaking stress values obtained for several different batches of parts.
  • a particular embodiment of the method of manufacturing a silicon-based timepiece component according to the invention comprises steps E1 to EN.
  • a first step E1 consists in etching in a silicon wafer, preferably by deep reactive ionic etching (DRIE), a part having the desired shape of the watch component.
  • DRIE deep reactive ionic etching
  • Silicon can be monocrystalline, polycrystalline or amorphous. For an isotropy of all physical characteristics, polysilicon may be preferred.
  • the silicon used in the invention may further be doped or not.
  • the part can be made from a composite material comprising thick layers of silicon separated by one or more thin intermediate layers of silicon oxide, by etching in a silicon-on-insulator substrate (SOI substrate).
  • SOI substrate silicon-on-insulator substrate
  • a second step E2 of the process is divided into two phases.
  • a first phase E2a the part is thermally oxidized, typically at a temperature between 600 ° C and 1300 ° C, preferably between 900 ° C and 1200 ° C, more preferably between 950 ° C and 1150 ° C, in an oxidizing atmosphere comprising, for example, oxygen gas or water vapor.
  • This oxidation is carried out until obtaining on the surface of the part a layer of silicon oxide (S1O2) of predetermined thickness typically between 0.5 ⁇ m and 2 ⁇ m and preferably equal to approximately 1 ⁇ m.
  • This silicon oxide layer is formed by growth while consuming silicon, which pushes back the interface between the silicon and the silicon oxide and attenuates the surface defects of the silicon.
  • a second phase E2b of step E2 the part is deoxidized, in other words the silicon oxide layer is eliminated, by for example by wet etching, vapor phase etching or dry etching, preferably by wet etching with hydrofluoric acid.
  • the second step E2 is then repeated at least once, with parameters which may be constant or which may vary from one oxidation - deoxidation sequence to another.
  • the thickness of silicon oxide formed with each oxidation is the same.
  • EN a total thickness of silicon has been removed from the part, the value of which is determined by the physical properties of silicon and silicon oxide and the parameters of the processing. thermal. Knowledge of these properties and parameters makes it possible to calculate the dimensions of the part to be engraved in step E1 to obtain the desired dimensions at the end of step EN.
  • said part is part of a batch of identical parts produced simultaneously in the same silicon wafer. After step EN, the part and the other parts of the batch are detached from the plate.
  • FIG. 2 shows the remarkable results obtained with the method according to the invention.
  • FIG. 2 shows the apparent breaking stress measured on bending test specimens at three identical points distributed in six different batches:
  • - Lot 3 test specimens manufactured by DRIE and having undergone thermal oxidation which coated them with a layer of silicon oxide 2 ⁇ m thick then deoxidation which eliminated this oxide layer (steps E1 and E2 uniquely).
  • - Lot 4 test specimens manufactured according to the process according to the invention (stages E1, E2 and E3), with two oxidation - deoxidation stages, the oxidation in each of these stages having led to the formation of a layer of 1 ⁇ m thick silicon oxide.
  • - Lot 5 test pieces manufactured by DRIE and having undergone thermal oxidation which coated them with a layer of silicon oxide 3 ⁇ m thick, then deoxidation which eliminated this oxide layer (steps E1 and E2 uniquely).
  • test specimens manufactured according to the process according to the invention (steps E1 to E4), with three oxidation - deoxidation steps, the oxidation in each of these steps having led to the formation of an oxide layer silicon 1 ⁇ m thick.
  • each box 50% of the parts and the two segments on either side of each box each represent 25% of the parts.
  • the horizontal line inside each box represents the median value.
  • the point represents the mean value.
  • Steps E3 to EN that is to say the repetition of step E2, advantageously replace the steps of annealing and of forming a final oxide layer.
  • silicon of the process described in patent application WO 2019/202378 and therefore greatly simplify the manufacture of the watch component.
  • the method according to the invention can be supplemented by a step consisting in coating the watch component with a final layer of silicon oxide, but the gain in mechanical strength provided by such a layer is quite limited or even non-existent compared to the drawback. that presents the implementation of an additional oxidation step.
  • a layer of a material having good tribological properties for example crystallized carbon in the form of diamond (DLC) or carbon nanotubes, a layer forming a barrier against oxygen or a layer, for example of parylene, serving to contain debris in the event of component rupture.
  • a material having good tribological properties for example crystallized carbon in the form of diamond (DLC) or carbon nanotubes
  • a layer forming a barrier against oxygen or a layer, for example of parylene serving to contain debris in the event of component rupture.
  • the invention is of particular interest for elastic watch components or with elastic parts which must withstand, during their operation or their assembly, high deformation stresses, such as motor springs (in particular barrel springs), certain return springs (in particular hammer, lever, rocker springs, pawl springs or jumper springs), watch components with flexible guidance (in particular oscillators, levers or rockers) or watch components (in particular wheels, ferrules, anchors or platform pegs) comprising elastic parts for mounting these components on support members such as axles.
  • motor springs in particular barrel springs
  • certain return springs in particular hammer, lever, rocker springs, pawl springs or jumper springs
  • watch components with flexible guidance in particular oscillators, levers or rockers
  • watch components in particular wheels, ferrules, anchors or platform pegs
  • Another advantageous application are watch springs, the number of operating cycles of which is high and which are therefore subject to fatigue failure, such as balance springs and blades of flexible guided oscillators.
  • the invention also applies to rigid watch components liable to undergo shocks during their operation, their handling or their assembly, in particular to balances, levers, levers, anchors, hammers, rakes, fingers, wheels, ferrules, axes, plate pegs, frame elements (in particular bridges), dials or indicator hands.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Optics & Photonics (AREA)
  • Metallurgy (AREA)
  • Plasma & Fusion (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Crystals, And After-Treatments Of Crystals (AREA)
  • Micromachines (AREA)

Abstract

The invention relates to a method for manufacturing a timepiece component according to which a silicon-based part having the desired form of the timepiece component is produced and the part is subjected to a thermal oxidation and deoxidation treatment to remove a predetermined thickness of silicon in order to increase the mechanical strength of the part. The method is characterised in that the thermal oxidation and deoxidation treatment is carried out in a plurality of steps, each step comprising a thermal oxidation phase followed by a deoxidation phase.

Description

Procédé de fabrication d’un composant horloger à base de silicium Manufacturing process of a silicon-based watch component
La présente invention concerne un procédé de fabrication d’un composant horloger à base de silicium, notamment pour montre-bracelet ou montre de poche. The present invention relates to a method of manufacturing a silicon-based horological component, in particular for a wristwatch or pocket watch.
Le silicium est un matériau très apprécié dans l'horlogerie mécanique pour ses propriétés avantageuses, notamment sa faible densité, sa grande résistance à la corrosion, son caractère amagnétique et son aptitude à être usiné par des techniques de micro-fabrication. On l’utilise ainsi pour fabriquer des ressorts spiraux, des balanciers, des oscillateurs à guidage flexible, des ancres d’échappement et des roues d’échappement. Silicon is a material highly valued in mechanical watchmaking for its advantageous properties, in particular its low density, its high resistance to corrosion, its non-magnetic nature and its ability to be machined by micro-manufacturing techniques. It is thus used to manufacture spiral springs, balances, flexibly guided oscillators, escapement anchors and escapement wheels.
Le silicium présente néanmoins l’inconvénient d’une faible résistance mécanique, inconvénient qui est aggravé par le mode de gravure généralement utilisé pour son usinage, la gravure ionique réactive profonde dite DRIE, qui laisse des arêtes vives et crée des défauts de planéité en forme de vaguelettes (appelés « scalloping » en anglais) sur les flancs de la pièce. Cette faible résistance mécanique est problématique pour la manipulation des composants lors de leur montage dans un mouvement ou en cas de chocs subis par la montre. Les composants peuvent en effet facilement se rompre. Pour répondre à ce problème, on renforce généralement les composants horlogers en silicium par un revêtement d’oxyde de silicium d’épaisseur très supérieure à celle de l’oxyde natif, comme décrit dans la demande de brevet WO 2007/000271. Ce revêtement est généralement laissé sur le composant final mais, selon l’enseignement de la demande de brevet EP 2277822, il peut être éliminé sans affecter sensiblement la résistance mécanique. Silicon nevertheless has the drawback of low mechanical strength, a drawback which is aggravated by the etching method generally used for its machining, deep reactive ionic etching known as DRIE, which leaves sharp edges and creates shape flatness defects. wavelets (called "scalloping" in English) on the sides of the room. This low mechanical strength is problematic for the handling of the components during their assembly in a movement or in the event of shocks undergone by the watch. The components can indeed easily break. To respond to this problem, the watch components made of silicon are generally reinforced by a coating of silicon oxide with a thickness much greater than that of the native oxide, as described in patent application WO 2007/000271. This coating is generally left on the final component but, according to the teaching of patent application EP 2277822, it can be removed without significantly affecting the mechanical strength.
Dans le cas des ressorts, la résistance mécanique doit en outre être suffisante pour que le composant puisse se déformer élastiquement sans rupture pendant son fonctionnement pour exercer sa fonction. Pour un ressort spiral destiné à équiper un balancier ou pour le guidage flexible d’un oscillateur sans pivots, les contraintes en fonctionnement sont relativement peu élevées, de l’ordre de quelques centaines de MPa au maximum, si bien que la résistance mécanique apportée par la couche d’oxyde de silicium peut en théorie suffire. Cependant, compte tenu des fréquences d’oscillation en fonctionnement (4 Hz, 10 Hz voire 50 Hz), le nombre de cycles est élevé, ce qui peut entraîner des risques de rupture par fatigue. Pour d’autres ressorts comme les ressorts moteurs, notamment ressorts de barillet, ou certains ressorts de marteau ou de bascule, les contraintes subies pendant leur fonctionnement sont beaucoup plus élevées, de l’ordre de quelques GPa, et imposent de choisir des matériaux de fabrication à haute limite élastique tels que des aciers, des alliages nickel-phosphore, le Nivaflex® (alliage à base de Co, Ni, Cr et Fe ayant une limite élastique d’environ 3,7 GPa), des verres métalliques (cf. brevets CH 698962 et CH 704391) ou des matériaux composites métal/diamant ou métalloïde/diamant (cf. brevet CH 706020 de la demanderesse). In the case of springs, the mechanical strength must also be sufficient for the component to be able to deform elastically without breaking during its operation in order to perform its function. For a spiral spring intended to equip a balance or for the flexible guidance of an oscillator without pivots, the operating stresses are relatively low, of the order of a few hundred MPa at most, so that the mechanical strength provided by the silicon oxide layer may in theory be sufficient. However, taking into account the oscillation frequencies in operation (4 Hz, 10 Hz or even 50 Hz), the number of cycles is high, which can lead to risks of rupture by fatigue. For other springs such as motor springs, in particular barrel springs, or certain hammer or rocker springs, the stresses undergone during their operation are much higher, of the order of a few GPa, and require the choice of materials of manufacture with high elastic limit such as steels, nickel-phosphorus alloys, Nivaflex® (alloy based on Co, Ni, Cr and Fe having an elastic limit of approximately 3.7 GPa), metallic glasses (cf. patents CH 698962 and CH 704391) or metal / diamond or metalloid / diamond composite materials (cf. patent CH 706020 of the applicant).
Depuis la demande de brevet WO 2019/202378 de la demanderesse, il est possible de réaliser des ressorts horlogers en silicium capables de résister à des contraintes particulièrement élevées et présentant en outre une grande résistance à la fatigue. Le procédé décrit dans cette demande de brevet comprend une succession d’étapes qui améliore considérablement la qualité des ressorts en silicium, notamment l’état de surface et l’arrondi des arêtes, ce qui se traduit par une contrainte de rupture moyenne proche de 5 GPa. Selon ce procédé, les ressorts sont successivement oxydés thermiquement, désoxydés, soumis à une opération de recuit dans une atmosphère réductrice et recouverts d’une couche d’oxyde de silicium, l’opération de recuit pouvant en variante être effectuée avant l’oxydation thermique. Ce procédé présente toutefois des inconvénients : l’étape de recuit est coûteuse à mettre en œuvre et nécessite l’emploi d’une machine encombrante. Since the Applicant's patent application WO 2019/202378, it is possible to produce silicon watch springs capable of withstanding particularly high stresses and also exhibiting great resistance to fatigue. The method described in this patent application comprises a succession of steps which considerably improves the quality of the silicon springs, in particular the surface condition and the rounding of the edges, which results in an average breaking stress close to 5. GPa. According to this process, the springs are successively thermally oxidized, deoxidized, subjected to an annealing operation in a reducing atmosphere and covered with a layer of silicon oxide, the annealing operation possibly being carried out before the thermal oxidation as a variant. . However, this process has drawbacks: the annealing step is expensive to implement and requires the use of a bulky machine.
La présente invention vise à remédier à ces inconvénients et plus généralement à permettre la fabrication, à coût modéré, d’un ressort ou autre composant horloger ayant une grande résistance mécanique. A cette fin, il est proposé un procédé de fabrication d’un composant horloger selon lequel on réalise à base de silicium une pièce ayant la forme souhaitée du composant horloger et on soumet la pièce à un traitement d’oxydation thermique et de désoxydation pour retirer une épaisseur prédéterminée de silicium afin d’augmenter la résistance mécanique de la pièce, caractérisé en ce que ledit traitement est effectué en plusieurs étapes, chaque étape comprenant une phase d’oxydation thermique suivie d’une phase de désoxydation. The present invention aims to remedy these drawbacks and more generally to allow the manufacture, at moderate cost, of a spring or other watch component having high mechanical strength. To this end, a method is proposed for manufacturing a watch component according to which a part having the desired shape of the watch component is produced on a silicon basis and the part is subjected to a thermal oxidation and deoxidation treatment in order to remove a predetermined thickness of silicon in order to increase the mechanical strength of the part, characterized in that said treatment is carried out in several stages, each stage comprising a thermal oxidation phase followed by a deoxidation phase.
Lorsqu’une pièce en silicium est oxydée thermiquement, la couche d’oxyde de silicium qui apparaît à sa surface se forme en consommant du silicium sur une profondeur correspondant à 44% de son épaisseur. Après avoir éliminé la couche d’oxyde de silicium, il reste donc une pièce en silicium de taille réduite, dont les défauts de surface (vaguelettes, fissures, brèches, etc.) constituant des amorces de rupture ont été atténués voire supprimés. When a silicon part is thermally oxidized, the silicon oxide layer that appears on its surface is formed by consuming silicon to a depth corresponding to 44% of its thickness. After removing the silicon oxide layer, there is therefore a silicon part of reduced size, whose surface defects (wavelets, cracks, gaps, etc.) constituting the initiators of fracture have been attenuated or even eliminated.
Cet effet est connu dans la technique antérieure et a été décrit par exemple dans la demande de brevet EP 2277822 mentionnée plus haut. La demanderesse a cependant constaté de manière surprenante que si l’on effectue la séquence d’oxydation - désoxydation en plusieurs fois, avec à chaque fois une phase d’oxydation thermique suivie d’une phase de désoxydation, la résistance mécanique du composant est très nettement améliorée. This effect is known in the prior art and has been described for example in the patent application EP 2277822 mentioned above. The Applicant has, however, surprisingly found that if the oxidation-deoxidation sequence is carried out in several stages, each time with a thermal oxidation phase followed by a deoxidation phase, the mechanical strength of the component is very high. significantly improved.
Il est certes connu dans la technique antérieure de mettre en œuvre plusieurs fois une séquence d’oxydation - désoxydation (cf. EP 3181938, WO 2019/166922, WO 2019/180596, EP 3416001) mais il s’agit toujours de procédés destinés à régler la raideur d’un spiral ou la fréquence d’un oscillateur et la répétition de la séquence d’oxydation - désoxydation n’a jamais pour but d’augmenter la résistance mécanique. De plus, dans ces procédés, les oxydations et désoxydations ne permettent pas de retirer une épaisseur prédéterminée de silicium. En effet, chaque nouvelle mise en œuvre de la séquence d’oxydation - désoxydation est précédée d’une étape de mesure de raideur ou de fréquence dont dépend l’épaisseur de silicium à retirer pendant ladite séquence. L’épaisseur totale de silicium à retirer ne peut donc pas être déterminée à l’avance, contrairement à la présente invention où cette épaisseur n’est liée à aucune mesure de raideur ou de fréquence du composant horloger. It is admittedly known in the prior art to implement an oxidation - deoxidation sequence several times (cf. EP 3181938, WO 2019/166922, WO 2019/180596, EP 3416001) but these are still processes intended for adjusting the stiffness of a hairspring or the frequency of an oscillator and repeating the oxidation - deoxidation sequence is never intended to increase mechanical strength. In addition, in these processes, the oxidations and deoxidations do not make it possible to remove a predetermined thickness of silicon. Indeed, each new implementation of the oxidation - deoxidation sequence is preceded by a stiffness or frequency measurement step. on which depends the thickness of silicon to be removed during said sequence. The total thickness of silicon to be removed cannot therefore be determined in advance, unlike the present invention where this thickness is not linked to any measurement of stiffness or frequency of the timepiece component.
Lorsque le composant horloger est un spiral ou un oscillateur à pivot flexible, le traitement d’oxydation thermique et de désoxydation du procédé selon l’invention peut être suivi d’étapes visant à régler la raideur ou la fréquence du composant par une ou plusieurs séquences d’oxydation - désoxydation précédées chacune d’une étape de mesure de la raideur ou de la fréquence et d’une étape de calcul de l’épaisseur de silicium à retirer, comme décrit par exemple dans les documents EP 3181938 et EP 3416001. When the watch component is a hairspring or a flexible pivot oscillator, the thermal oxidation and deoxidation treatment of the method according to the invention can be followed by steps aimed at adjusting the stiffness or the frequency of the component by one or more sequences. oxidation - deoxidation each preceded by a step of measuring the stiffness or the frequency and by a step of calculating the thickness of silicon to be removed, as described for example in documents EP 3181938 and EP 3416001.
Le réglage de la raideur ou de la fréquence peut en variante être effectué avant le traitement d’oxydation thermique et de désoxydation selon l’invention. Compte tenu de l’épaisseur prédéterminée de silicium enlevée par le traitement d’oxydation thermique et de désoxydation selon l’invention, on sait en effet à quelle raideur ou fréquence il faut régler le composant pour obtenir une raideur ou fréquence souhaitée après le traitement. The adjustment of the stiffness or the frequency can alternatively be carried out before the thermal oxidation and deoxidation treatment according to the invention. In view of the predetermined thickness of silicon removed by the thermal oxidation and deoxidation treatment according to the invention, it is in fact known at what stiffness or frequency to adjust the component in order to obtain a desired stiffness or frequency after the treatment.
Il est également possible de compléter le procédé selon l’invention par la formation d’une couche finale sur la pièce, par exemple une couche d’oxyde de silicium, une couche améliorant les propriétés tribologiques, une couche formant une barrière contre l’oxygène ou une couche servant à contenir d’éventuels débris, même si, en ce qui concerne la couche d’oxyde de silicium, celle-ci est rendue superflue par la répétition des phases d’oxydation thermique et de désoxydation, comme il sera démontré dans la suite. It is also possible to complete the method according to the invention by forming a final layer on the part, for example a layer of silicon oxide, a layer improving tribological properties, a layer forming a barrier against oxygen. or a layer serving to contain any debris, even if, as regards the silicon oxide layer, this is made superfluous by the repetition of the thermal oxidation and deoxidation phases, as will be demonstrated in the following.
D’autres caractéristiques et avantages de la présente invention apparaîtront à la lecture de la description détaillée suivante faite en référence aux dessins annexés dans lesquels : Other characteristics and advantages of the present invention will become apparent on reading the following detailed description given with reference to the accompanying drawings in which:
- la figure 1 est un schéma montrant les différentes étapes d’un procédé de fabrication selon un mode de réalisation particulier de l’invention ; - les figures 2 et 3 sont des graphiques montrant par des boîtes à moustaches des valeurs de contrainte de rupture apparente obtenues pour plusieurs lots différents de pièces. - Figure 1 is a diagram showing the different steps of a manufacturing process according to a particular embodiment of the invention; - Figures 2 and 3 are graphs showing by boxplots the apparent breaking stress values obtained for several different batches of parts.
En référence à la figure 1 , un mode de réalisation particulier du procédé de fabrication d’un composant horloger à base de silicium selon l’invention comprend des étapes E1 à EN. Referring to Figure 1, a particular embodiment of the method of manufacturing a silicon-based timepiece component according to the invention comprises steps E1 to EN.
Une première étape E1 consiste à graver dans une plaquette de silicium, de préférence par gravure ionique réactive profonde (DRIE), une pièce ayant la forme souhaitée du composant horloger. A first step E1 consists in etching in a silicon wafer, preferably by deep reactive ionic etching (DRIE), a part having the desired shape of the watch component.
Le silicium peut être monocristallin, polycristallin ou amorphe. Pour une isotropie de l’ensemble des caractéristiques physiques, le silicium polycristallin peut être préféré. Le silicium utilisé dans l’invention peut en outre être dopé ou non. A la place du silicium proprement dit, la pièce peut être réalisée dans un matériau composite comprenant des couches épaisses de silicium séparées par une ou plusieurs couches minces intermédiaires d’oxyde de silicium, par gravure dans un substrat silicium sur isolant (substrat SOI). Silicon can be monocrystalline, polycrystalline or amorphous. For an isotropy of all physical characteristics, polysilicon may be preferred. The silicon used in the invention may further be doped or not. Instead of the silicon itself, the part can be made from a composite material comprising thick layers of silicon separated by one or more thin intermediate layers of silicon oxide, by etching in a silicon-on-insulator substrate (SOI substrate).
Une deuxième étape E2 du procédé se divise en deux phases. Dans une première phase E2a, la pièce est oxydée thermiquement, typiquement à une température comprise entre 600°C et 1300°C, de préférence entre 900°C et 1200°C, de préférence encore entre 950°C et 1150°C, dans une atmosphère oxydante comprenant par exemple du gaz de dioxygène ou de la vapeur d’eau. Cette oxydation est mise en oeuvre jusqu’à obtenir sur la surface de la pièce une couche d’oxyde de silicium (S1O2) d’épaisseur prédéterminée typiquement comprise entre 0,5 pm et 2 pm et de préférence égale à environ 1 pm. Cette couche d’oxyde de silicium se forme par croissance en consommant du silicium, ce qui fait reculer l’interface entre le silicium et l’oxyde de silicium et atténue les défauts de surface du silicium. Dans une deuxième phase E2b de l’étape E2, la pièce est désoxydée, autrement dit la couche d’oxyde de silicium est éliminée, par exemple par gravure humide, gravure en phase vapeur ou gravure sèche, de préférence par gravure humide à l’acide fluorhydrique. A second step E2 of the process is divided into two phases. In a first phase E2a, the part is thermally oxidized, typically at a temperature between 600 ° C and 1300 ° C, preferably between 900 ° C and 1200 ° C, more preferably between 950 ° C and 1150 ° C, in an oxidizing atmosphere comprising, for example, oxygen gas or water vapor. This oxidation is carried out until obtaining on the surface of the part a layer of silicon oxide (S1O2) of predetermined thickness typically between 0.5 μm and 2 μm and preferably equal to approximately 1 μm. This silicon oxide layer is formed by growth while consuming silicon, which pushes back the interface between the silicon and the silicon oxide and attenuates the surface defects of the silicon. In a second phase E2b of step E2, the part is deoxidized, in other words the silicon oxide layer is eliminated, by for example by wet etching, vapor phase etching or dry etching, preferably by wet etching with hydrofluoric acid.
La deuxième étape E2 est ensuite répétée au moins une fois, avec des paramètres qui peuvent être constants ou qui peuvent varier d’une séquence d’oxydation - désoxydation à une autre. De préférence, toutefois, l’épaisseur d’oxyde de silicium formée à chaque oxydation est la même. A la fin de la dernière étape d’oxydation - désoxydation, EN, une épaisseur totale de silicium a été retirée de la pièce, dont la valeur est déterminée par les propriétés physiques du silicium et de l’oxyde de silicium et les paramètres du traitement thermique. La connaissance de ces propriétés et paramètres permet de calculer les dimensions de la pièce à graver à l’étape E1 pour obtenir les dimensions voulues à l’issue de l’étape EN. The second step E2 is then repeated at least once, with parameters which may be constant or which may vary from one oxidation - deoxidation sequence to another. Preferably, however, the thickness of silicon oxide formed with each oxidation is the same. At the end of the last stage of oxidation - deoxidation, EN, a total thickness of silicon has been removed from the part, the value of which is determined by the physical properties of silicon and silicon oxide and the parameters of the processing. thermal. Knowledge of these properties and parameters makes it possible to calculate the dimensions of the part to be engraved in step E1 to obtain the desired dimensions at the end of step EN.
Typiquement, ladite pièce fait partie d’un lot de pièces identiques réalisées simultanément dans une même plaquette de silicium. Après l’étape EN, la pièce et les autres pièces du lot sont détachées de la plaquette. Typically, said part is part of a batch of identical parts produced simultaneously in the same silicon wafer. After step EN, the part and the other parts of the batch are detached from the plate.
La figure 2 montre les résultats remarquables obtenus avec le procédé selon l’invention. A titre de comparaison, on a représenté à la figure 2 la contrainte de rupture apparente mesurée sur des éprouvettes de flexion trois points identiques réparties en six lots différents : Figure 2 shows the remarkable results obtained with the method according to the invention. By way of comparison, FIG. 2 shows the apparent breaking stress measured on bending test specimens at three identical points distributed in six different batches:
- Lot 1 : des éprouvettes fabriquées uniquement par DRIE (étape E1 uniquement). Ce lot est le lot de référence. - Lot 1: test specimens manufactured only by DRIE (step E1 only). This lot is the reference lot.
- Lot 2 : des éprouvettes fabriquées par DRIE et ayant subi une oxydation thermique qui les a revêtues d’une couche d’oxyde de silicium de 1 pm d’épaisseur puis une désoxydation qui a éliminé cette couche d’oxyde (étapes E1 et E2 uniquement). - Lot 2: test pieces manufactured by DRIE and having undergone thermal oxidation which coated them with a layer of silicon oxide 1 μm thick, then deoxidation which eliminated this oxide layer (steps E1 and E2 uniquely).
- Lot 3 : des éprouvettes fabriquées par DRIE et ayant subi une oxydation thermique qui les a revêtues d’une couche d’oxyde de silicium de 2 pm d’épaisseur puis une désoxydation qui a éliminé cette couche d’oxyde (étapes E1 et E2 uniquement). - Lot 4 : des éprouvettes fabriquées selon le procédé selon l’invention (étapes E1, E2 et E3), avec deux étapes d’oxydation - désoxydation, l’oxydation dans chacune de ces étapes ayant conduit à la formation d’une couche d’oxyde de silicium de 1 pm d’épaisseur. - Lot 5 : des éprouvettes fabriquées par DRIE et ayant subi une oxydation thermique qui les a revêtues d’une couche d’oxyde de silicium de 3 pm d’épaisseur puis une désoxydation qui a éliminé cette couche d’oxyde (étapes E1 et E2 uniquement). - Lot 3: test specimens manufactured by DRIE and having undergone thermal oxidation which coated them with a layer of silicon oxide 2 μm thick then deoxidation which eliminated this oxide layer (steps E1 and E2 uniquely). - Lot 4: test specimens manufactured according to the process according to the invention (stages E1, E2 and E3), with two oxidation - deoxidation stages, the oxidation in each of these stages having led to the formation of a layer of 1 µm thick silicon oxide. - Lot 5: test pieces manufactured by DRIE and having undergone thermal oxidation which coated them with a layer of silicon oxide 3 μm thick, then deoxidation which eliminated this oxide layer (steps E1 and E2 uniquely).
- Lot 6 : des éprouvettes fabriquées selon le procédé selon l’invention (étapes E1 à E4), avec trois étapes d’oxydation - désoxydation, l’oxydation dans chacune de ces étapes ayant conduit à la formation d’une couche d’oxyde de silicium de 1 pm d’épaisseur. - Lot 6: test specimens manufactured according to the process according to the invention (steps E1 to E4), with three oxidation - deoxidation steps, the oxidation in each of these steps having led to the formation of an oxide layer silicon 1 µm thick.
Toutes ces éprouvettes sont fabriquées à partir de la même plaquette de silicium. Dans le graphique de la figure 2, les boîtes rectangulaires représententAll of these specimens are made from the same silicon wafer. In the graph of figure 2, the rectangular boxes represent
50% des pièces et les deux segments de part et d’autre de chaque boîte représentent chacun 25% des pièces. Le trait horizontal à l’intérieur de chaque boîte représente la valeur médiane. Le point représente la valeur moyenne. 50% of the parts and the two segments on either side of each box each represent 25% of the parts. The horizontal line inside each box represents the median value. The point represents the mean value.
Il est intéressant de constater que la valeur moyenne ainsi que l’extrémité inférieure de la boîte, qui correspond à la valeur de contrainte de rupture apparente minimale pour une population comptant 75% des pièces, sont bien plus élevées pour les lots 4 et 6 fabriqués selon l’invention que pour les lots 3 et 5 respectivement. L’invention met donc en évidence que pour une même épaisseur de silicium retirée, il est préférable de réaliser l’oxydation - désoxydation en plusieurs fois même si cela implique la mise en oeuvre de plusieurs opérations de désoxydation, l’avantage obtenu en termes de résistance mécanique l’emportant largement sur cet inconvénient. It is interesting to note that the average value as well as the lower end of the box, which corresponds to the value of minimum apparent breaking stress for a population of 75% of the parts, are much higher for batches 4 and 6 manufactured. according to the invention only for lots 3 and 5 respectively. The invention therefore demonstrates that for the same thickness of silicon removed, it is preferable to carry out the oxidation - deoxidation in several times even if this involves the implementation of several deoxidation operations, the advantage obtained in terms of mechanical strength largely outweighing this drawback.
Les étapes E3 à EN, c’est-à-dire la répétition de l’étape E2, remplacent avantageusement les étapes de recuit et de formation d’une couche finale d’oxyde de silicium du procédé décrit dans la demande de brevet WO 2019/202378 et simplifient donc grandement la fabrication du composant horloger. Le procédé selon l’invention peut être complété par une étape consistant à revêtir le composant horloger d’une couche finale d’oxyde de silicium mais le gain de résistance mécanique apporté par une telle couche est assez limité voire inexistant par rapport à l’inconvénient que présente la mise en œuvre d’une étape d’oxydation supplémentaire. Ceci est illustré par le graphique de la figure 3 sur lequel on peut voir que des éprouvettes de flexion trois points réalisées par DRIE et ayant subi deux séquences d’oxydation - désoxydation avec la formation d’une épaisseur de 1 pm d’oxyde à chaque oxydation (lot 7) ont statistiquement une résistance mécanique voisine de celle d’éprouvettes obtenues et traitées de la même manière, et issues de la même plaquette de silicium, mais en plus recouvertes d’une couche finale de 1 pm d’oxyde thermique (lot 8) ou d’une couche finale de 3 pm d’oxyde thermique (lot 9). Par conséquent, au lieu de revêtir le composant horloger d’une couche finale d’oxyde de silicium, on peut laisser le composant final se recouvrir naturellement d’une mince couche d’oxyde natif. En variante, on peut former sur le composant horloger une couche d’un matériau ayant de bonnes propriétés tribologiques, par exemple du carbone cristallisé sous forme de diamant (DLC) ou des nanotubes de carbone, une couche formant une barrière contre l’oxygène ou une couche, par exemple en parylène, servant à contenir les débris en cas de rupture du composant. Steps E3 to EN, that is to say the repetition of step E2, advantageously replace the steps of annealing and of forming a final oxide layer. silicon of the process described in patent application WO 2019/202378 and therefore greatly simplify the manufacture of the watch component. The method according to the invention can be supplemented by a step consisting in coating the watch component with a final layer of silicon oxide, but the gain in mechanical strength provided by such a layer is quite limited or even non-existent compared to the drawback. that presents the implementation of an additional oxidation step. This is illustrated by the graph of Figure 3 on which it can be seen that three-point bending specimens produced by DRIE and having undergone two oxidation - deoxidation sequences with the formation of a thickness of 1 μm of oxide at each oxidation (batch 7) have statistically a mechanical resistance close to that of test pieces obtained and treated in the same way, and coming from the same silicon wafer, but in addition covered with a final layer of 1 μm of thermal oxide ( lot 8) or a final layer of 3 μm of thermal oxide (lot 9). Therefore, instead of coating the watch component with a final layer of silicon oxide, the final component can be allowed to be naturally covered with a thin layer of native oxide. As a variant, it is possible to form on the watch component a layer of a material having good tribological properties, for example crystallized carbon in the form of diamond (DLC) or carbon nanotubes, a layer forming a barrier against oxygen or a layer, for example of parylene, serving to contain debris in the event of component rupture.
L’invention présente un intérêt particulier pour les composants horlogers élastiques ou à parties élastiques qui doivent résister pendant leur fonctionnement ou leur montage à de fortes contraintes de déformation, tels que les ressorts moteurs (notamment ressorts de barillet), certains ressorts de rappel (notamment des ressorts de marteau, de levier, de bascule, des ressorts cliquets ou des ressorts sautoirs), des composants horlogers à guidage flexible (notamment des oscillateurs, leviers ou bascules) ou des composants horlogers (notamment des roues, viroles, ancres ou chevilles de plateau) comprenant des parties élastiques servant au montage de ces composants sur des organes de support tels que des axes. Une autre application avantageuse sont les ressorts horlogers dont le nombre de cycles de fonctionnement est élevé et qui sont donc sujets à des ruptures par fatigue, comme les spiraux et lames des oscillateurs à guidage flexible. Mais l’invention s’applique aussi à des composants horlogers rigides susceptibles de subir des chocs pendant leur fonctionnement, leur manipulation ou leur montage, en particulier à des balanciers, leviers, bascules, ancres, marteaux, râteaux, doigts, roues, viroles, axes, chevilles de plateau, éléments de bâti (notamment ponts), cadrans ou aiguilles indicatrices. The invention is of particular interest for elastic watch components or with elastic parts which must withstand, during their operation or their assembly, high deformation stresses, such as motor springs (in particular barrel springs), certain return springs (in particular hammer, lever, rocker springs, pawl springs or jumper springs), watch components with flexible guidance (in particular oscillators, levers or rockers) or watch components (in particular wheels, ferrules, anchors or platform pegs) comprising elastic parts for mounting these components on support members such as axles. Another advantageous application are watch springs, the number of operating cycles of which is high and which are therefore subject to fatigue failure, such as balance springs and blades of flexible guided oscillators. But the invention also applies to rigid watch components liable to undergo shocks during their operation, their handling or their assembly, in particular to balances, levers, levers, anchors, hammers, rakes, fingers, wheels, ferrules, axes, plate pegs, frame elements (in particular bridges), dials or indicator hands.

Claims

REVENDICATIONS
1. Procédé de fabrication d’un composant horloger selon lequel on réalise à base de silicium une pièce ayant la forme souhaitée du composant horloger et on soumet la pièce à un traitement d’oxydation thermique et de désoxydation pour retirer une épaisseur prédéterminée de silicium afin d’augmenter la résistance mécanique de la pièce, caractérisé en ce que ledit traitement est effectué en plusieurs étapes, chaque étape comprenant une phase d’oxydation thermique suivie d’une phase de désoxydation. 1. A method of manufacturing a watch component according to which a part having the desired shape of the watch component is produced on a silicon basis and the part is subjected to a thermal oxidation and deoxidation treatment to remove a predetermined thickness of silicon in order to to increase the mechanical strength of the part, characterized in that said treatment is carried out in several stages, each stage comprising a thermal oxidation phase followed by a deoxidation phase.
2. Procédé selon la revendication 1, caractérisé en ce que l’opération de réalisation de la pièce comprend une opération de gravure d’une plaquette à base de silicium. 2. Method according to claim 1, characterized in that the operation of producing the part comprises an operation of etching a silicon-based wafer.
3. Procédé selon la revendication 2, caractérisé en ce que la gravure est une gravure ionique réactive profonde. 3. Method according to claim 2, characterized in that the etching is a deep reactive ionic etching.
4. Procédé selon l’une quelconque des revendications 1 à 3, caractérisé en ce que chaque phase d’oxydation thermique est effectuée à une température comprise entre 600°C et 1300°C, de préférence entre 900°C et 1200°C, de préférence entre 950°C et 1150°C. 4. Method according to any one of claims 1 to 3, characterized in that each thermal oxidation phase is carried out at a temperature between 600 ° C and 1300 ° C, preferably between 900 ° C and 1200 ° C, preferably between 950 ° C and 1150 ° C.
5. Procédé selon l’une quelconque des revendications 1 à 4, caractérisé en ce que chaque phase de désoxydation comprend une opération de gravure, par exemple une opération de gravure humide, de gravure en phase vapeur ou de gravure sèche. 5. Method according to any one of claims 1 to 4, characterized in that each deoxidation phase comprises an etching operation, for example a wet etching, vapor phase etching or dry etching operation.
6. Procédé selon l’une quelconque des revendications 1 à 5, caractérisé en ce que chaque phase d’oxydation thermique conduit à la formation d’une couche d’oxyde de silicium d’épaisseur comprise entre 0,5 et 2 pm et de préférence égale à environ 1 pm. 6. Method according to any one of claims 1 to 5, characterized in that each thermal oxidation phase leads to the formation of a layer of silicon oxide with a thickness of between 0.5 and 2 μm and of preferably equal to about 1 µm.
7. Procédé selon l’une quelconque des revendications 1 à 6, caractérisé en ce que le traitement d’oxydation thermique et de désoxydation n’est pas suivi d’une étape de formation d’une couche finale d’oxyde de silicium. 7. Method according to any one of claims 1 to 6, characterized in that the thermal oxidation and deoxidation treatment is not followed by a step of forming a final layer of silicon oxide.
8. Procédé selon l’une quelconque des revendications 1 à 7, caractérisé en ce que le composant horloger est élastique ou comprend au moins une partie élastique. 8. Method according to any one of claims 1 to 7, characterized in that the watch component is elastic or comprises at least one elastic part.
9. Procédé selon l’une quelconque des revendications 1 à 8, caractérisé en ce que le composant horloger est un ressort moteur, un ressort de marteau, un ressort de levier, un ressort de bascule, un ressort de râteau, un ressort cliquet, un ressort sautoir, un ressort spiral, un composant horloger comprenant un guidage flexible ou un composant horloger comprenant une ou des parties élastiques servant à son montage sur un organe de support tel qu’un axe. 9. Method according to any one of claims 1 to 8, characterized in that the horological component is a mainspring, a hammer spring, a lever spring, a rocking spring, a rake spring, a pawl spring, a jumper spring, a spiral spring, a watch component comprising a flexible guide or a watch component comprising one or more elastic parts serving for its mounting on a support member such as an axis.
10. Procédé selon l’une quelconque des revendications 1 à 8, caractérisé en ce que le composant horloger est un balancier, un levier, une bascule, une ancre, un marteau, un râteau, un doigt, une roue, une virole, un axe, une cheville de plateau, un élément de bâti, un cadran ou une aiguille indicatrice. 10. Method according to any one of claims 1 to 8, characterized in that the horological component is a balance, a lever, a lever, an anchor, a hammer, a rake, a finger, a wheel, a ferrule, a axis, a plate pin, a frame element, a dial or an indicator hand.
11. Composant horloger obtenu par le procédé selon l’une quelconque des revendications 1 à 10. 11. Timepiece component obtained by the method according to any one of claims 1 to 10.
EP21712581.4A 2020-03-19 2021-03-16 Method for manufacturing a silicon-based timepiece component Pending EP4121821A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP20164297.2A EP3882710A1 (en) 2020-03-19 2020-03-19 Method for manufacturing a silicon-based clock component
PCT/IB2021/052155 WO2021186332A1 (en) 2020-03-19 2021-03-16 Method for manufacturing a silicon-based timepiece component

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EP21712581.4A Pending EP4121821A1 (en) 2020-03-19 2021-03-16 Method for manufacturing a silicon-based timepiece component

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EP (2) EP3882710A1 (en)
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WO (1) WO2021186332A1 (en)

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JP2008544290A (en) 2005-06-28 2008-12-04 ウーテーアー・エス・アー・マニファクチュール・オロロジェール・スイス Enhanced micromechanical parts
CH706020B1 (en) 2007-09-07 2013-07-31 Patek Philippe Sa Geneve Motor spring for watch movement barrel with increased running time.
CH698962B1 (en) 2008-06-10 2014-10-31 Rolex Sa Barrel spring and method for its shaping.
EP2277822A1 (en) 2009-07-23 2011-01-26 Montres Breguet S.A. Method for manufacturing a micromechanical element from reinforced silicon
WO2011069273A1 (en) 2009-12-09 2011-06-16 Rolex S.A. Method for making a spring for a timepiece
EP3181938B1 (en) 2015-12-18 2019-02-20 CSEM Centre Suisse d'Electronique et de Microtechnique SA - Recherche et Développement Method for manufacturing a hairspring with a predetermined stiffness by removing material
EP3416001B1 (en) 2017-06-13 2022-04-13 Patek Philippe SA Genève Method for manufacturing an oscillator with flexible pivot
TWI774925B (en) 2018-03-01 2022-08-21 瑞士商Ｃｓｅｍ瑞士電子及微技術研發公司 Method for manufacturing a spiral spring
EP3543795A1 (en) 2018-03-20 2019-09-25 Patek Philippe SA Genève Method for manufacturing silicon clock components
EP3557333B1 (en) 2018-04-16 2020-11-04 Patek Philippe SA Genève Method for manufacturing a timepiece mainspring

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US20230126149A1 (en) 2023-04-27
CN115298620A (en) 2022-11-04
EP3882710A1 (en) 2021-09-22
WO2021186332A1 (en) 2021-09-23

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