EP4303666A1 - Uhrenkomponente mit einem substrat aus kristallinem silizium und mit verbesserter bruchfestigkeit - Google Patents

Uhrenkomponente mit einem substrat aus kristallinem silizium und mit verbesserter bruchfestigkeit Download PDF

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Publication number
EP4303666A1
EP4303666A1 EP22183437.7A EP22183437A EP4303666A1 EP 4303666 A1 EP4303666 A1 EP 4303666A1 EP 22183437 A EP22183437 A EP 22183437A EP 4303666 A1 EP4303666 A1 EP 4303666A1
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EP
European Patent Office
Prior art keywords
substrate
passivation layer
component
less
silicon
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
EP22183437.7A
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English (en)
French (fr)
Inventor
Evelyne Vallat
Andreas Hogg
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.)
ASSOCIATION SUISSE POUR LA RECHERCHE HORLOGERE
Original Assignee
ASSOCIATION SUISSE POUR LA RECHERCHE HORLOGERE
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.)
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Publication date
Application filed by ASSOCIATION SUISSE POUR LA RECHERCHE HORLOGERE filed Critical ASSOCIATION SUISSE POUR LA RECHERCHE HORLOGERE
Priority to EP22183437.7A priority Critical patent/EP4303666A1/de
Publication of EP4303666A1 publication Critical patent/EP4303666A1/de
Pending legal-status Critical Current

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    • 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
    • G04B39/00—Watch crystals; Fastening or sealing of crystals; Clock glasses
    • 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
    • G04B31/00—Bearings; Point suspensions or counter-point suspensions; Pivot bearings; Single parts therefor
    • G04B31/004—Bearings; Point suspensions or counter-point suspensions; Pivot bearings; Single parts therefor characterised by the material used

Definitions

  • the present invention relates to a watch component comprising a crystalline silicon substrate and having improved breaking strength, as well as a method of manufacturing said component.
  • Crystalline silicon including monocrystalline silicon or polycrystalline silicon, is a material increasingly used in the manufacture of mechanical parts and in particular micromechanical parts. Compared to metals or alloys conventionally used to manufacture micromechanical parts, crystalline silicon has the advantage of having a density 3 to 4 times lower and therefore of having very reduced inertia, and of being insensitive to magnetic fields. . These advantages are particularly interesting in the watchmaking field, both with regard to isochronism and running time. Crystalline silicon also allows it to be micro-machined with great precision.
  • crystalline silicon shows mechanical performance reduced by the presence of defects (scratches, microcracks, microporosities, inclusions, impurities, etc.). These defects are caused during the production of the silicon wafer and during the shaping of the crystalline silicon component. These defects are generally the cause of slow crack growth.
  • the slow propagation of cracks can be compared to stress corrosion linked to the presence of OH- ions in ambient humidity and which accelerates the propagation of cracks which are the microscopic origin of the rupture of fragile materials.
  • the miniaturization of the component makes it possible to reduce the probability of the existence of millimeter defects (scratches, microcracks) given that a smaller component will statistically have fewer defects.
  • the use of crystalline silicon is therefore more interesting for the manufacture of small components, for example components of millimeter or sub-centimeter size, as is the case in the case of micromechanical and watchmaking components.
  • passivation layers have been developed for electronic devices in monocrystalline materials commonly used in opto-electronic applications (in particular: silicon, GaAs, etc.) whose main technical characteristic is the perfection of the essential monocrystalline network. to ensure optimal operation of the device.
  • the current performance of the devices is limited by the presence of defects (generally atomic) on the surface or at the interfaces.
  • the various passivation solutions developed in the electronic and PV sector based on monocrystalline silicon consist of coating the surface of the active volume with a thin layer, most often amorphous, composed of amorphous silicon (a-Si:H), oxide silicon (SiO2), silicon carbide (SiC), silicon nitride (Si3N4) or a composition resulting from their mixture (e.g.: oxynitrides, silicon oxycarbide) or their stacking sequence
  • the silicon component can be covered with a layer of thermal silicon oxide.
  • This type of coating is also suitable for the tribological stresses to which the surface of the component must respond in micromechanical and watchmaking applications.
  • An aim of the invention is the application of an electronic quality passivation layer for improving the mechanical performance of crystalline silicon in components on the millimeter to sub-centimeter scale.
  • Another aim of the invention is to improve the mechanical performance, such as the breaking strength of crystalline silicon, for its use in microcomponents of millimeter to submillimeter size, for example of the watchmaking component type.
  • a passivation layer on the surface of a component so as to reduce the surface density of point defects (non-coordinated or sub-coordinated connections type) and isolate the component. of its atmospheric environment which is at the origin of the acceleration of the propagation of cracks leading to rupture.
  • the invention relates to a watch component with improved breaking strength comprising a crystalline silicon substrate having a lateral dimension of the order of a few centimeters or less and a thickness of the order of a millimeter or less.
  • the substrate is coated with a passivation layer, directly in contact with the surface of the substrate and having a thickness of less than 1000 nm, preferably less than 600 nm or preferably less than 400 nm.
  • the passivation layer comprises a refractory ceramic comprising at least 1 atomic% of hydrogen.
  • the low thickness of the passivation layer makes it possible to obtain high dimensional precision of the component. This is particularly advantageous in micromechanical and watchmaking applications.
  • FIG. 1 shows, schematically, a watch component 10 comprising a crystalline silicon substrate 20 having a lateral dimension of the order of a few centimeters or less and a thickness of the order of a millimeter or less.
  • the substrate 20 is coated with a passivation layer 30, directly in contact with the surface 25 of the substrate 20.
  • Crystalline silicon may include monocrystalline silicon or polycrystalline silicon.
  • the passivation layer 30 has a thickness of less than 1000 nm, preferably less than 600 nm or preferably less than 400 nm.
  • the passivation layer 30 comprises a refractory ceramic comprising at least 1 atomic% of hydrogen.
  • the passivation layer 30 makes it possible to reduce the density of surface defects of the substrate 20, improving, among other things, impact resistance.
  • the passivation layer also makes it possible to isolate the substrate 20 (and therefore the component 10) from the ambient atmosphere, and therefore from the chemical compounds which are at the origin of the acceleration of the propagation of the cracks leading to rupture.
  • the choice of one or other of the chemical compositions of the passivation layer 30, as well as its thickness may also depend on the characteristics required for the coating, for example the ability to transport charge, transparency, conformity , deposition temperature, hardness, chemical barrier to ionic migration, tribological behavior, chemical compatibility with lubricants, etc.
  • the refractory ceramic comprises one of the following elements: a hydrogenated silicon oxynitride (SiON:H), hydrogenated silicon oxycarbide (SiOxCy:H), hydrogenated silicon carbide (SiC:H), nitride hydrogenated silicon (Si3N4:H), or a combination of these ceramics.
  • the passivation layer 30 of refractory ceramic comprising a SiON:H, SiOxCy:H, SiC:H or Si3N4:H ceramic, or a combination of these ceramics make it possible, for example, to modify the visual appearance of the component (aesthetic), to provide a hermetic barrier to the transport of ions, in particular OH- ions, towards the substrate 20.
  • a hydrogen content of the order of a few atomic percent makes it possible to saturate the defects constituted by unsaturated atomic bonds on the surface 25 of the substrate 20.
  • hydrogen allows to reduce the density of dangling bonds.
  • the passivation layer 30 comprising a refractory ceramic comprising at least 1 atomic % of hydrogen makes it possible to improve the breaking resistance of the component 10.
  • the resistance to rupture is inversely proportional to the density of defects potentially causing a microcrack whose propagation will lead to the failure of the component 10.
  • the passivation layer comprising a refractory ceramic comprising at least 1 atomic % of hydrogen makes it possible to reduce the surface density of defects on the surface 25 of the substrate 20. A reduction in the surface density of defects increases the mechanical resistance, and in particular the breaking strength, of component 10.
  • a thickness less than 1000 nm, less than 600 nm, or less than 400 nm, allows the passivation layer 30 to play a role as a barrier to the penetration of impurities catalyzing or accelerating the propagation of microcracks.
  • the performance of the passivation layer 30, in particular the reduction in the density of surface defects of the substrate 20 and the insulation of the substrate 20 of the ambient atmosphere, depend on the surface condition 25 of the substrate 20.
  • the surface 25 of the substrate 20 must not be affected by machining. We will therefore seek to eliminate, or at least minimize, defects such as scratches and microcracks on the surface 25 of the substrate 20.
  • the surface 25 of the substrate 20 on which the passivation layer 30 is formed is smoothed, or polished, so as to obtain a roughness Ra of less than 100 nm.
  • FIG 2 shows a schematic and sectional view of the surface 25.
  • the surface 25 is leveled so that the surface 25 of the substrate 20 has a surface topology comprising asperities 27 or rounded dimples having a radius of curvature greater than 500 nm, preferably greater than 4 ⁇ m.
  • the surface 25 is leveled and does not have any facets or acute angles which could result in a possible concentration of stresses during mechanical stress.
  • the surface 25 of the substrate 20 must also be clean, that is to say, having a controlled chemical state of the surface.
  • a controlled chemical state of the surface can mean that the surface 25 of the substrate 20 does not contain substantially no contamination by particles, native oxides (due to humidity and oxygen in the air), materials organic matter, layer residue, inorganic bases or acids or other metallic contamination.
  • the chemical composition on the surface 25 is as close as possible to the mass chemical composition of the substrate 20.
  • the study of the conformity of the growth of the passivation layer 30 shows that all the surfaces of a component 10 bringing together characteristic watchmaking elements such as that escapement teeth, holes (diameter 3 mm to 0.2 mm), slender beam, tongue, tip and re-entrant element), are coated to satisfaction by the passivation layer 30.
  • the substrate 20 may be coated with the passivation layer 30 on one, several or all of its surfaces 25.
  • the passivation layer 30 may be formed on all surfaces 25 of the substrate 20.
  • the three-dimensional component 10 has a passivation layer 30 of substantially uniform thickness on all its surfaces 25.
  • the watch component may comprise a component of a display or covering device.
  • the formation of the passivation layer 30 can be carried out by a chemical vapor deposition process.
  • the formation of the passivation layer 30 can be carried out by a plasma-assisted chemical vapor deposition (PECVD) process dedicated to the uniform three-dimensional coating of the component 10.
  • PECVD plasma-assisted chemical vapor deposition
  • the passivation layer 30 can be produced in a reactor comprising rotation/mixing/turning means which facilitate uniform deposition of the passivation layer 30 on one or a plurality of three-dimensional components 10, as described in the Swiss patent application CH715599 .
  • gentle and low temperature covering processes are favored, such as thermal growth or layer deposition by PECVD. .
  • the method may further comprise a step of chemical dissolution in the vapor or liquid phase of the surface 25 of the substrate 20, prior to the step of forming the passivation layer 30.
  • the step of machining the substrate 20 may include selectively chemically dissolving the substrate 20 and releasing the machined component 10.
  • the machining step may comprise one of the following processes: deep reactive-ion etching (DRIE), or very short pulse laser marking (femto to pico seconds).
  • DRIE deep reactive-ion etching
  • Femto to pico seconds very short pulse laser marking
  • the machining step can optionally be followed by selective chemical dissolution of the marked volume (or selective laser engraving).
  • the method comprises a step of smoothing and/or leveling the surface 25 of the substrate 20 so as to obtain roughnesses or rounded dimples with a radius of curvature greater than 500 nm, preferably greater than 4 ⁇ m.
  • the smoothing and/or leveling step may also include polishing the surface 25 receiving the passivation layer 30.
  • the polishing is carried out with an optical quality resulting in a roughness Ra of less than 1 nm.
  • the step of smoothing and/or leveling the surface 25 is carried out before the formation of the passivation layer 30.
  • the method comprises a step of cleaning the surface, carried out before the formation of the passivation layer 30 in order to obtain a controlled chemical state of the surface, that is to say that the surface 25 contains substantially no particulate contamination, native oxides (due to moisture and oxygen in the air), organic matter, layer residue, inorganic bases or acids or other metal contamination.
  • the surface cleaning step is carried out before the formation of the passivation layer 30.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Formation Of Insulating Films (AREA)
EP22183437.7A 2022-07-06 2022-07-06 Uhrenkomponente mit einem substrat aus kristallinem silizium und mit verbesserter bruchfestigkeit Pending EP4303666A1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP22183437.7A EP4303666A1 (de) 2022-07-06 2022-07-06 Uhrenkomponente mit einem substrat aus kristallinem silizium und mit verbesserter bruchfestigkeit

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP22183437.7A EP4303666A1 (de) 2022-07-06 2022-07-06 Uhrenkomponente mit einem substrat aus kristallinem silizium und mit verbesserter bruchfestigkeit

Publications (1)

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EP4303666A1 true EP4303666A1 (de) 2024-01-10

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EP22183437.7A Pending EP4303666A1 (de) 2022-07-06 2022-07-06 Uhrenkomponente mit einem substrat aus kristallinem silizium und mit verbesserter bruchfestigkeit

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2945025A1 (de) * 2014-05-16 2015-11-18 Nivarox-FAR S.A. Uhrwerksmechanismus mit ungeschmierter Kontaktkupplung
EP3141519A1 (de) * 2015-09-08 2017-03-15 Nivarox-FAR S.A. Herstellungsverfahren für ein mikromechanisches uhrenbauteil und entsprechendes mikromechanisches uhrenbauteil
CH715599A2 (fr) 2018-11-28 2020-05-29 Coat X Sa Réacteur de dépôt multicouche.
EP3783445A1 (de) * 2019-08-22 2021-02-24 ETA SA Manufacture Horlogère Suisse Einstellmechanismus einer uhr mit hohem qualitätsfaktor und minimaler schmierung

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP2945025A1 (de) * 2014-05-16 2015-11-18 Nivarox-FAR S.A. Uhrwerksmechanismus mit ungeschmierter Kontaktkupplung
EP3141519A1 (de) * 2015-09-08 2017-03-15 Nivarox-FAR S.A. Herstellungsverfahren für ein mikromechanisches uhrenbauteil und entsprechendes mikromechanisches uhrenbauteil
CH715599A2 (fr) 2018-11-28 2020-05-29 Coat X Sa Réacteur de dépôt multicouche.
EP3783445A1 (de) * 2019-08-22 2021-02-24 ETA SA Manufacture Horlogère Suisse Einstellmechanismus einer uhr mit hohem qualitätsfaktor und minimaler schmierung

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