CH711501B1 - Method for manufacturing a micromechanical timepiece and said micromechanical timepiece. - Google Patents

Abstract

The invention relates to a method of manufacturing a micromechanical timepiece from a silicon-based substrate (1), comprising, in order, the steps of: a) providing a substrate for silicon-based (1), b) forming pores (2) on the surface of at least part of a surface of said silicon-based substrate (1) with a depth of at least 10 µm, preferably at least 50 µm, and more preferably at least 100 µm, said pores being arranged to open onto the external surface of the micromechanical timepiece, and optionally a deposition step, the final form of the silicon-based substrate in function of the micromechanical timepiece to be manufactured being donated before step a) or after step b). The invention also relates to a micromechanical timepiece comprising a silicon-based substrate (1) which has, on the surface of at least part of a surface of said silicon-based substrate (1), pores (2) with a depth of at least 10 µm, preferably at least 50 µm, and more preferably at least 100 µm, said pores being arranged to open onto the external surface of the micromechanical timepiece

Description

Field of the invention

The present invention relates to a method for producing micromechanical watch parts based on silicon. The invention also relates to a reinforced micromechanical timepiece, based on silicon, which can in particular be obtained by such a method.

Invention background

[0002] Silicon is an increasingly used material in the manufacture of watchmaking micromechanical parts, in particular parts which remain linked to a silicon-based substrate on which they have been machined.

Compared with the metals or alloys conventionally used to manufacture micromechanical watch parts, such as toothed wheels, or the components of the escapement, silicon has many advantages. It is a very hard material, with a very light weight which therefore allows it to have a very reduced inertia and consequently to improve the yield. Silicon also makes it possible to produce complex, or monobloc, parts.

In order to improve or modify the properties of silicon, it is known to deposit on silicon a layer of an appropriate material. Thus, to improve its tribological properties, diamond is deposited on silicon, for example by a thin layer vapor deposition (CVD / PVD) process.

However, these methods have a deposition rate which may prove to be too slow when the thickness of the deposited layer exceeds a few microns. Indeed, the deposition rates in CVD machines for example being typically of the order of ten nanometers / minute, this technique is generally not used for the manufacture of a layer greater than a few microns.

It is therefore necessary to propose a method for manufacturing a micromechanical timepiece based on silicon making it possible to rapidly deposit thick layers of an appropriate material on the silicon.

[0007] Furthermore, silicon-based substrates can be used to make dials.

The dials of watches or other timepieces include inscriptions or decorative surfaces allowing to give indications or to enhance the dial. These decorations are traditionally made by different engraving techniques.

When the dial is made from silicon, it is necessary to propose new techniques for making such inscriptions or decorative surfaces, which are easy to implement.

Furthermore, just like the other materials used more conventionally in watchmaking, the parts produced from a silicon-based substrate must be lubricated.

It is known to use, for example, a very fluid lubricating agent which promotes a low coefficient of friction in the case of low contact pressures. However, this type of lubricant has the drawback of seeing its effect fade, in particular during higher contact pressures due to the rupture of the lubricating film. It is known that the super-lubrication techniques, based on the formation of polymer brushes (polymer brushes) deposited on the surface and their impregnation with a lubricant having an affinity with polymer brushes, make it possible to greatly reduce friction for a wide range of solicitations. These very flexible polymer brushes straighten when they are impregnated with the lubricant, thus forming a kind of sponge saturated with lubricant. According to the friction regimes, at high contact pressures, the filaments can easily compress and restore lubricant in the contact. This results in the formation of a larger lubricating film which results in a substantial reduction in the coefficient of friction and wear. However, during long-term stresses, these polymer brushes end up degrading (wear, tearing of the surface), which no longer allows the coating of polymer brushes to perform its function.

It is therefore necessary to propose a new method for lubricating a micromechanical watch piece based on silicon allowing to contain on the surface of the piece to be lubricated sufficient quantities of lubricating agent in order to reduce the frequency of maintenance services. of the watch movement comprising said piece.

It is also necessary to propose a new method for lubricating a micromechanical watch piece based on silicon, making it possible to create lubrication conditions allowing a significant reduction in wear and in the coefficient of friction, so as to increase reliability, the performance and therefore the power reserve of the timepiece movement comprising this piece, and this for a wide range of stresses.

Summary of the invention

To this end, the present invention relates to a process for manufacturing a micromechanical timepiece comprising a silicon-based substrate, comprising, in order, the steps of: <tb> a) <SEP> be provided with a silicon-based substrate <tb> b) <SEP> forming pores on the surface of at least part of a surface of said silicon-based substrate with a depth of at least 10 μm, preferably at least 50 μm, and more preferably at least 100 μm, said pores being arranged to lead to the external surface of the micromechanical timepiece, and optionally a deposition step, the final shape of the silicon-based substrate depending on the part to be manufactured being given before step a) or after step b).

The method according to the invention allows, thanks to the prior formation of pores on the surface of the substrate, to improve different properties of a silicon-based substrate used in micromechanical watch parts.

The present invention also relates to a micromechanical timepiece capable of being obtained by the method as defined above.

The present invention also relates to a micromechanical timepiece comprising a silicon-based substrate which has, on the surface of at least part of a surface of said silicon-based substrate, pores with a depth of at least 10 μm, preferably at least 50 μm, and more preferably at least 100 μm, said pores being arranged to open onto the external surface of the micromechanical timepiece.

According to a first variant, the pores can be entirely filled with a layer of a material chosen from diamond, carbon-diamond (DLC), silicon oxide, silicon nitride, ceramics, polymers and their mixtures, of a thickness at least equal to the depth of the pores. A surface layer of said material can be provided on the surface of the silicon-based substrate and pores filled with the material.

According to another variant, the pores can be arranged to form a decorative surface, said decorative surface being covered with a coating comprising a metallization layer and / or a transparent oxide layer chosen from the group comprising SiO2, TiO2 , ZrO2, HfO2, Ta2O5, VO2.

According to another variant, the pores may include a tribological agent. The part may then comprise, between the pores, silicon-based filaments, the silicon-based filaments comprising walls covered with at least one wetting agent of the tribological agent, the silicon-based filaments being impregnated with the tribological agent. The silicon-based filaments may also have walls covered with at least one polymer brush, the silicon-based filaments and the polymer brush being impregnated with the tribological agent.

According to another variant, the pores can be arranged on the silicon-based substrate to constitute at least one superhydrophobic zone with an epilame effect relative to at least one zone of the silicon-based substrate not comprising a pore and on which is applied a tribological agent.

Brief description of the drawings

The aims, advantages and characteristics of the present invention will appear more clearly in the following detailed description of various embodiments of the invention given solely by way of nonlimiting examples and illustrated by the appended drawings in which: FIGS. 1 to 3 schematically illustrate the steps of a manufacturing method according to the invention, FIGS. 4 to 6 schematically illustrate the steps of another variant of the manufacturing method according to the invention, and Figures 7 to 9 schematically illustrate the steps of another variant of the manufacturing method according to the invention.

Detailed description of the invention

The method of manufacturing a micromechanical timepiece comprising a silicon-based substrate according to the invention comprises, in order, the steps of: <tb> a) <SEP> be provided with a silicon-based substrate <tb> b) <SEP> forming pores from the surface of at least part of a surface of said silicon-based substrate with a depth of at least 10 µm, preferably at least 50 μm, and more preferably at least 100 μm, said pores being arranged to open onto the external surface of the micromechanical timepiece, and optionally a deposition step, the final shape of the silicon-based substrate as a function of the micromechanical timepiece to be manufactured being given before step a) or after step b).

The silicon-based substrate is chosen according to the micromechanical timepiece to be formed. In the present invention, the expression “silicon-based substrate” denotes both a layer of silicon in a substrate and a substrate of silicon. Preferably, as shown in FIG. 1, the silicon-based substrate 1 is a silicon wafer or an SOI wafer (Silicon-on-lnsulator). The pores can be formed both on the surface parallel to the plane of the substrate and on the surface perpendicular to the plane of the substrate.

Advantageously, this step b) can be carried out by a process chosen from the group comprising a process by electrochemical attack, a process of the "Stain-etch" type, and a process of the "MAC-Etch" type. .

The process by electrochemical attack can be a process by electrochemical anodization. Its implementation requires the use of an electrochemical bath containing hydrofluoric acid in aqueous solution or mixed with ethanol in concentrations of 1 to 10%. An electric current and electrodes are necessary to create electrochemical conditions inducing the attack of silicon. Depending on the electrochemical conditions, different types of pores can be obtained. Such a method is known to those skilled in the art and does not require detailed information here.

The “Stain-etch” type process is based on a wet etching of the silicon leading directly to the formation of porous silicon. Typically, the attack is done with an HF / HNO3 / H2O solution with an HF: HNO3 ratio of 50-500: 1. This method has the advantage of not requiring an electrical supply in the bath. Such a method is known to those skilled in the art and does not require detailed information here.

Preferably, step b) is carried out by a method of the "MAC-Etch" type. This process is based on the use of noble metal particles to catalyze local chemical attack reactions. Typically, a very thin layer (10-50 nm) of a noble metal (gold, silver, platinum) is deposited and structured randomly or by lift-off, etching, laser, etc. Preferably, the noble metal is gold. More particularly, it is possible to advantageously use gold particles in solution in an HF / H2O2 mixture. The size of the particles can be between 5 and 1000 nm. Structuring can be obtained by gold lithography, attack or lift-off. Another option is the evaporation or sputtering of a very thin unclosed layer (5-30 nm). Heat treatment can contribute to the formation of gold islands.

When the silicon with the noble metal layer is immersed in an aqueous solution of an HF / H2O2 mixture, the noble metal locally catalyzes the dissolution of the silicon. This attack solution can typically comprise between 4 ml: 1 ml: 8 ml (HF: H2O2: H2O) and 4 ml: 1 ml: 40 ml (HF: H2O2: H2O). The dissolution of silicon preferably occurs under the metal, the latter then gradually sinking into the silicon. This reaction can continue over great depths (> 100 mµ) according to propagation modes essentially influenced by the orientation of the silicon crystal, the arrangement of the surfaces, the doping and the chemistry of the bath. The “MAC-Etch” type process has the advantage of not requiring an electrical supply in the bath while allowing the formation of pores of very great depth (> 100 μm) in the silicon. It is therefore particularly suitable for the use, as a substrate, of SOI wafers generally used for the manufacture of watch components.

Those skilled in the art know the parameters of the methods described above to be implemented so that the pores formed in the silicon-based substrate have an appropriate geometry and size.

In particular, the pores can advantageously have an aspect factor (depth: diameter ratio) of between 1 and 200.

Preferably, the pores may have a depth greater than 200 μm and more preferably greater than 300 μm.

As shown in Figure 2, the formation of pores 2 in the silicon-based substrate 1 to a certain depth results in the formation, between the pores 2, of pillars 3 based on silicon on the same depth. Preferably, considering the silicon-based pillars as having a circular section, the pores 2 are formed so that the projected area of the silicon-based pillars 3 is less than 79% of the total apparent surface so as not to have of silicon-based pillars that touch each other.

According to a first variant of the method of the invention, with reference to Figures 1 to 3, the substrate based on porous silicon is used to create an actual surface of the substrate much greater than the initial surface, and therefore to increase strongly the apparent deposition rate of a suitable material.

According to this first variant, the method according to the invention comprises, after step b), a step c) consisting in completely filling the pores 2 formed in the silicon-based substrate 1 during step b) , of a material chosen from diamond, carbon-diamond (DLC), silicon oxide, silicon nitride, ceramics, polymers and their mixtures, in order to form in the pores a layer of said material. a thickness at least equal to the depth of the pores.

Thus, the method according to the invention allows to manufacture, on the surface of the silicon-based substrate, a thick layer of a suitable material in a fast time, greatly reduced compared to a deposit on the flat surface of a similar, but non-porous substrate.

This step c) is carried out directly after step b), without any intermediate step, so that the material deposited in the pores is in direct contact with the walls of said pores.

Preferably, step c) is carried out by a method chosen from the group comprising thin film deposition methods, such as chemical vapor deposition (CVD), physical vapor deposition (PVD) methods. ), atomic thin film deposition (ALD), and thermal oxidation. These methods are known to those skilled in the art and do not require detailed information here. It can however be specified that when step c) is carried out by PVD deposition, the aspect factor of the pores in the silicon-based substrate is preferably less than or equal to 4: 1. When step c) is carried out by CVD or MOCVD (metal organic chemical vapor deposition) deposition, the aspect factor of the pores in the silicon-based substrate is preferably less than or equal to 50: 1. In addition, for a PVD deposition, the deposition rate will preferably be between 0.1 and 5 nm / s. For a CVD or MOCVD deposition, the deposition rate will preferably be between 0.01 and 10 nm / s. For an ALD deposition, the deposition rate will be for example 0.01 nm / s. Furthermore, thermal oxidation is particularly advantageous for reducing the proportion of silicon in a silicon substrate, the silicon being consumed by growth at the rate of approximately 50% of the thickness of the layer. Thus, a person skilled in the art knows how to size the pores to be formed in a silicon substrate in order to allow 100% replacement of the silicon with SiO2, thus resulting in the formation of a very thick SiO2 layer in a very short time. .

Advantageously, the method according to the invention comprises, after step c), a step d) of forming a surface layer 4 of said material on the surface of the substrate 1 and pores 2 filled with the material. More particularly, this surface layer 4 can be obtained by extending the deposition of the material according to step c) so as not only to completely fill the pores 2 of the material but also to then deposit said material on the pores 2 filled with the material thus as on the pillars 3 to form a solid layer 4 of said material of thickness h0, as shown in FIG. 3. A composite layer of thickness h1 is thus obtained comprising the pillars 3, the pores 2 filled with material and the solid layer 4. Thus, one can have for example a ratio h0 / h1 of the order of 10%.

Thus, the method according to the invention provides a micromechanical timepiece comprising a thick composite layer based on silicon / deposited material, or even a thick layer of deposited material when all the silicon has been replaced.

The formation of pores from the surface of the substrate during step b) makes it possible to create a very strong corrugation in order to create an actual surface much greater than the initial surface, without pores. A person skilled in the art knows how to choose the geometry of the pores as well as the time for depositing the material in the pores, in order to fabricate, on the surface of the silicon, a thick layer in a greatly reduced time compared to a deposit on a flat surface. More particularly, the person skilled in the art knows how to choose the geometry and the size of the pores so as to: obtain complete filling of the pores when the material is deposited, facilitate gas flow obtain the desired volume ratio between the layer of deposited material and the silicon pores. It is possible, for example, to manufacture porous silicon with a porosity of more than 90% if necessary. For example, for certain deposition processes such as CVD and PVD, the deposition rate tends to be slower at the bottom of the pores. It is then possible to provide conical pores (wider at the surface than at depth) in order to compensate for this phenomenon linked to the flow of gases.

Thus, with a sufficient supply of gas into the pores, the method according to the invention makes it possible to obtain a composite silicon / deposited layer of thickness h1 in a deposition time close to that necessary for obtaining d '' a full layer of material of thickness h0 corresponding to the surface layer 4.

The method according to the invention can advantageously be implemented for the manufacture of silicon-based exhaust components, such as the escape wheel and the anchor, by forming thick layers of diamond by CVD .

The method according to the invention can also be implemented for the manufacture of silicon-based exhaust components, by forming thick layers of SiO2, almost solid if the process by thermal oxidation is used for deposition of SiO2.

The method according to the invention can also be implemented to quickly create very thick local layers deep in the silicon, by combining it with the structuring of porous silicon zones.

According to a second variant of the method of the invention, the pores 2 are formed according to step b) on an area of the silicon-based substrate 1 corresponding to a decorative surface to be produced. The substrate based on porous silicon is then used to create on the watchmaking micromechanical piece a decorative porous silicon surface of very dark color, close to black. The pores 2 are arranged so as to open out to the external surface of the micromechanical timepiece, in order to form a surface visible to the user.

Those skilled in the art know the parameters of the methods described above to be implemented so that the pores formed in the silicon-based substrate have a geometry and a size suitable for obtaining a porous silicon zone having a very high light absorption power, especially in the visible area, and anti-reflective.

In particular, by assimilating the pores, in the plane of the part, to orifices of circular section, said pores may preferably have a diameter between 10 nm and 1000 nm.

The color area obtained is used as a decorative surface on the micromechanical timepiece. By decorative surface is meant for example a drawing, a pattern or an inscription, such as figures, or any other decoration.

The method according to the invention can optionally comprise, after step b), a step e) consisting in depositing at least one coating on the decorative porous silicon surface obtained according to step b).

Advantageously, this coating deposited in step e) may comprise a metallization layer based on at least one of the elements chosen from the group comprising Cr, Ti, Ag, Pt, Cu, Ni, Pd, Preferably, the metallization layer is a thin layer, of thickness less than 50 nm.

Advantageously, the coating deposited in step e) can also comprise a transparent oxide layer, such as one of the oxides chosen from the group comprising SiO2, TiO2, ZrO2, HfO2, Ta2O5, VO2, or their mixtures. The metallization layer or the oxide layer can be used alone, and be deposited for example directly on the porous Si, or the two layers can be combined, the oxide layer then covering the metallization layer. The thickness of the oxide layer is preferably between 100 nm and 2000 nm.

The coating of a metallization layer and a transparent oxide layer on the decorative surface of porous silicon makes it possible to obtain a decorative surface of interference colors.

The method according to the invention can advantageously be implemented for the manufacture of parts based on silicon, such as dials.

According to another variant of the process of the invention, the formation of pores from the surface of the silicon-based substrate makes it possible to form a superstructure based on porous silicon having a certain degree of flexibility capable of accommodating different pressure regimes by deforming. In addition, this type of structure has cavities which make it possible to permanently contain a large reserve of lubricant.

In addition, in the case where polymer brushes are deposited on the superstructure based on porous silicon, the coating obtained is capable of filling with lubricant and restoring it when these polymer brushes are compressed. This coating also promotes the penetration of the lubricant into the cavities of the superstructure based on porous silicon.

According to this variant, the pores 2 are formed from the surface of said silicon-based substrate 1 on an area of the silicon-based substrate 1 corresponding to an area to be lubricated with a tribological agent. The pores may preferably be formed on the surface perpendicular to the plane of the substrate, that is to say on the sides of the micromechanical part which are in friction, but also on the surface parallel to the plane of the substrate.

According to this variant, there is provided, after step b), a step f) consisting in depositing in the pores 2, between the pillars 3, a tribological agent. The tribological agent is a lubricant, and can be liquid, for example in the form of an aqueous solution, or dry. Preferably, said tribological agent is a perfluorocarbon polymer, such as polytetrafluoroethylene (PTFE), or any other suitable tribological agent or lubricant.

According to a first embodiment, the tribological agent is deposited according to step f) directly in the pores 2 of the silicon-based substrate. This step f) can be carried out by a thin layer deposition method, such as CVD, iCVD, PECVD. A suitable heat treatment can be applied to polymerize the tribological agent, at temperatures of the order of 100 ° C to 300 ° C. Thus, large quantities of tribological agent can be stored near the surface of the silicon-based substrate, while retaining a relatively high apparent surface hardness due to the silicon.

In a particularly advantageous manner, the parameters of the process for forming the pores 2 in the silicon-based substrate 1 according to step b) are chosen so that the pores 2 have an appropriate geometry and size so that the pillars 3, formed between the pores 2, constitute filaments 3 ′ based on silicon. These 3 'filaments have an aspect factor (depth: diameter ratio) of between 5 and 100. The filaments form a flexible superstructure and are then impregnated with a tribological agent chosen to facilitate wetting of the pores, in accordance with step b) of the process according to the invention.

A substrate comprising silicon-based filaments can be used according to two other embodiments of this variant of the method of the invention.

More particularly with reference to Figures 4 to 6, according to a second embodiment, it is provided in accordance with step b) to produce in a silicon-based substrate 1 pores 2 so as to form between the pores 2 of the pillars 3 in the form of filaments 3 ′, as shown in FIG. 4. There is then provided between steps b) and f), a step g) of depositing at least one wetting agent 6 of the tribological agent on the walls of the 3 ′ silicon-based filaments. The wetting agent 6 is chosen to facilitate wetting and penetration of the tribological agent. It is applied to form a very thin layer (a few nanometers) in order to functionalize the walls of the 3 'silicon-based filaments. Then the filaments 3 ′ are impregnated with a tribological agent 5, according to step f), the tribological agent 5 being chosen to facilitate wetting of the pores 2.

Referring to Figures 7 to 9, according to a third embodiment, it is provided in accordance with step b) to produce in a silicon-based substrate 1 pores 2 so as to form between the pores 2 pillars 3 in the form of filaments 3 ', as shown in FIG. 7. There is then provided between steps b) and f), a step h) of depositing at least one polymer brush 8 on the walls of the filaments 3 'based on silicon. Such a polymer brush 8 is described for example in the publications WO 2012/152512 and WO 2014/009059. Polymer brushes have shorter filaments than silicon-based filaments so that the polymer filaments are protected by the more mechanically strong silicon-based filaments. Then the silicon-based filaments 3 ′ and the polymer brushes 8 are impregnated with a tribological agent 5, according to step f), the tribological agent 5 being chosen to facilitate wetting.

This process variant makes it possible to manufacture filaments directly in the material of the silicon-based substrate with controlled geometries and mechanical bending properties allowing, in the case of the use of polymer brushes, to maintain the behavior of super-lubrication over a wide range of friction conditions while increasing reliability. Thus, the method according to the invention overcomes the lack of mechanical strength of the polymer brushes usually used in super-lubrication. The structure formed of silicon-based filaments constitutes a reservoir of lubricant capable of restoring the sufficient quantity of lubricant in the contact according to the stresses.

The geometry of the pores and silicon-based filaments can be optimized as a function of the friction regimes and tribological objectives targeted. The structure of the silicon-based substrate can range from silicon-based filaments to open and disordered pores forming a spongy layer

According to another variant of the process of the invention, the pores 2 are formed on the silicon-based substrate 1 to constitute at least one superhydrophobic zone with an epilam effect with respect to at least one zone of the silicon-based substrate not comprising a pore and to which a tribological agent is applied. This effect can be reinforced by localized functionalization.

Claims (26)

1. Method for manufacturing a micromechanical timepiece comprising a silicon-based substrate (1), the method comprising, in order, the steps of: a) providing a silicon-based substrate (1), b) forming pores (2) on the surface of at least part of a surface of said silicon-based substrate (1) with a depth of at least 10 μm, preferably at least 50 μm, and more preferably at least 100 μm, said pores being arranged to open onto the external surface of the micromechanical timepiece, and optionally a deposit step, the final shape of the silicon-based substrate (1) as a function of the micromechanical timepiece to be manufactured being given before step a) or after step b). 2. Method according to claim 1, comprising after step b), the deposition step which is a step c) consisting in completely filling said pores (2) with a material chosen from diamond, carbon-diamond, also called DLC, silicon oxide, silicon nitride, ceramics, polymers and their mixtures, in order to form in the pores (2) a layer of said material with a thickness at least equal to the depth of the pores ( 2). 3. Method according to claim 2, comprising after step c), a step d) of forming a surface layer (4) of said material on the surface of the silicon-based substrate (1) and pores (2 ) filled with material. 4. The method of claim 1, wherein the pores (2) are formed on an area of the silicon-based substrate (1) corresponding to a decorative surface. 5. Method according to claim 4, characterized in that it comprises, after step b), the deposition step which is a step e) of deposition of a coating on the decorative surface. 6. Method according to claim 5, characterized in that the coating comprises a metallization layer. 7. Method according to one of claims 5 and 6, characterized in that the coating comprises a transparent oxide layer chosen from the group comprising SiO2, TiO2, ZrO2, HfO2, Ta2O5, VO2. 8. Method according to claim 1, comprising after step b), the deposition step which is a step f) consisting in depositing in said pores (2) a tribological agent (5), said pores (2) being formed on the surface of at least part of a surface to be lubricated of said silicon-based substrate (1). 9. The method of claim 8, wherein the pores (2) are arranged so as to form, between the pores, filaments (3 ') based on silicon having an aspect factor, that is to say a depth: diameter ratio between 5 and 100. 10. The method of claim 8 or 9, comprising, between steps b) and f), a step g) of depositing at least one wetting agent (6) of the tribological agent (5) on the walls of the filaments (3 ') based on silicon. 11. The method of claim 8 or 9, comprising, between steps b) and f), a step h) of depositing at least one polymer brush (8) on the walls of the silicon-based filaments (3 ') . 12. Method according to one of claims 8 to 11, wherein the tribological agent (5) is a perfluorocarbon polymer. 13. The method of claim 1, wherein the pores (2) are formed on the silicon-based substrate (1) to form at least one superhydrophobic zone with an epilamous effect relative to at least one zone of the silicon-based substrate not comprising a pore and to which a tribological agent is applied during the deposition step. 14. Method according to one of claims 1 to 13, in which step b) is carried out by a method chosen from the group comprising a method by electrochemical attack, a method of the "Stain-etch" type, and a method of type "MAC-Etch". 15. The method of claim 14, wherein step b) is performed by a type of method "MAC-Etch". 16. Method according to one of the preceding claims, in which the pores have an aspect factor, that is to say a depth: diameter ratio between 1 and 200. 17. Method according to one of the preceding claims, in which the pores (2) have a depth greater than 200 µm and more preferably greater than 300 µm. 18. Method according to one of the preceding claims, in which the silicon-based substrate (1) is a silicon wafer or an SOI wafer, short for Silicon-on-Insulator. 19. Watchmaking micromechanical part comprising a silicon-based substrate (1) which has, on the surface of at least part of a surface of said silicon-based substrate (1), pores (2) of a depth at least 10 µm, preferably at least 50 µm, and more preferably at least 100 µm, said pores being arranged to open onto the external surface of the micromechanical timepiece. 20. Part according to claim 19, characterized in that said pores (2) are completely filled with a layer of a material chosen from diamond, carbon-diamond, also called DLC, silicon oxide, nitride of silicon, ceramics, polymers and their mixtures, of a thickness at least equal to the depth of the pores (2). 21. Part according to claim 20, characterized in that it comprises a surface layer of said material on the surface of the silicon-based substrate (1) and pores (2) filled with the material. 22. Part according to claim 19, characterized in that the pores (2) are arranged to form a decorative surface, and in that said decorative surface is covered with a coating comprising a metallization layer and / or a transparent layer d oxide selected from the group comprising SiO2, TiO2, ZrO2, HfO2, Ta2O5, VO2. 23. Part according to claim 19, characterized in that the pores (2) comprise a tribological agent (5). 24. Part according to claim 23, characterized in that it comprises, between the pores (2), filaments (3 ') based on silicon, the filaments (3') based on silicon having walls covered with at least one wetting agent (6) of the tribological agent (5), the filaments (3 ') based on silicon being impregnated with the tribological agent (5). 25. Part according to claim 23, characterized in that it comprises, between the pores (2), filaments (3 ') based on silicon, the filaments (3') based on silicon having walls covered with at least one polymer brush (8), the filaments (3 ') based on silicon and the polymer brush (8) being impregnated with the tribological agent (5). 26. Part according to claim 19, characterized in that the pores (2) are arranged on the silicon-based substrate (1) to constitute at least one superhydrophobic zone with an epilamous effect relative to at least one zone of the substrate based of silicon not comprising a pore and to which a tribological agent is applied.