Method for manufacturing mechanical resonators

Abstract

One aspect of the invention relates to a method for manufacturing a set of mechanical resonators (2a) whose structural characteristics have an average value within a predetermined numerical range, comprising the steps of: forming (21) mechanical resonators (2b, 2c) and oscillating members (10a, 10b, 10c) in a substrate (1); calculating a dimensional correction value to be applied to the formed resonator (2b, 2c) on the basis of a value determined for the structural characteristic; then, the dimensions of the formed resonators (2b, 2c) are modified (28) on the basis of the calculated dimension correction values to obtain a set of resonators (2a) having structural characteristic values within a predetermined numerical range.

Description

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202511847510.7 (22) Application Date 2025.12.09 (30) Priority Data 24219838.0 2024.12.13 EP (71) Applicant Nivallos-Fal GmbH Address Switzerland (72) Inventor G. Chasan P. Carson (74) Patent Agency Beijing Zhongzi Law Firm 11247 Patent Attorney Gao Meiyan Wu Peng (51) Int.Cl. H03H 9 / 24 (2006.01) H03H 3 / 00 (2006.01) G04B 17 / 20 (2006.01) (54) Invention Title: Method for Manufacturing Mechanical Resonators (57) Abstract: One aspect of the present invention relates to a method for manufacturing a set of mechanical resonators (2a) whose average structural characteristics are within a predetermined numerical range, the method comprising the steps of: forming (21) mechanical resonators (2b, 2c) and oscillating members (10a, 10b, 10c) in a substrate (1); calculating a size correction value to be applied to the formed resonators (2b, 2c) based on a value determined for the structural characteristics; and then modifying (28) the size of the formed resonators (2b, 2c) based on the calculated size correction value to obtain a set of resonators (2a) whose structural characteristic values ​​are within a predetermined numerical range.Claims 2 pages, Description 9 pages, Drawings 4 pages, CN 122226008 A 2026.06.16 CN 1 22 22 60 08 A 1. A method for manufacturing a set of mechanical resonators (2a) having an average structural characteristic within a predetermined range, the structural characteristic being common to each mechanical resonator (2a) in the set of mechanical resonators (2a), the method comprising the steps of: a) step (20) forming mechanical resonators (2b, 2c) in a substrate (1), the size of the mechanical resonators (2b, 2c) being different from the size required to obtain the set of mechanical resonators (2a) with structural characteristics within the predetermined range; (b) Step (21) forming at least one oscillating member (10a, 10b, 10c) in the substrate (1), the at least one oscillating member (10a, 10b, 10c) being formed in the opening (9) of the substrate (1), the oscillating member (10a, 10b, 10c) being composed of a main body (6) and two flexible arms (7, 8), the body of the main body (6) being connected at the first end (5a) to the fixing part (15) of the outer peripheral wall (13) of the opening (9), the two flexible arms being connected to the second end (5d) of the main body (6) through the connecting part (14), the two flexible arms (7, 8) being parallel to the axis of symmetry (A) of the main body (6) and extending toward the fixing part (15), the axial section (S1) of the second end (5d) being smaller than the axial section (S2) of the first end (5a) and larger than the axial section (S3) of each of the flexible arms (7, 8); c) Determining step (22), in which a value related to the structural characteristics of the formed at least one oscillating member (10a, 10b, 10c) is determined; d) Calculating step (26), in which a size correction value to be applied to the formed mechanical resonators (2b, 2c) is calculated based on the value determined for the structural characteristics; e) Modifying step (28), in which the size of the formed mechanical resonators (2b, 2c) is modified based on the calculated size correction value to obtain the set of mechanical resonators (2a) with structural characteristic values ​​within a predetermined range. 2. The method according to claim 1, characterized in that, in step (21) of forming the oscillating members (10a, 10b, 10c), each of the flexible arms (7, 8) is given a length (L) that can be adjusted according to a resonance measurement tolerance factor defined by at least one dimension (E2, E3, H2, H3) of the flexible portion (3) of the mechanical resonator (2b, 2c) associated with the at least one oscillating member (10a, 10b, 10c).3. The method according to any one of the preceding claims, characterized in that, in step (21) of forming the oscillating members (10a, 10b, 10c), each flexible arm is positioned at a first distance (D1) and a second distance (D2) from the body of the main body (6) and the fixing portion (15) of the outer peripheral wall (13) of the opening (9), respectively, wherein the first distance (D1) is greater than the second distance (D2). 4. The method according to any one of the preceding claims, characterized in that, in step (21) of forming the oscillating members (10a, 10b, 10c), the thickness (Er) of each of the flexible arms (7, 8) is equal to or substantially equal to the thickness of the flexible portion (3) of each mechanical resonator (2b, 2c) formed in the substrate (1). 5. The method according to any one of the preceding claims, characterized in that, in step (21) of forming the oscillating members (10a, 10b, 10c), the free end (5b, 5c) of each of the flexible arms (7, 8) is integrally formed with an end member (11, 12), the mass of the end member being greater than the mass of the rest of the body of the flexible arm (7, 8). 6. The method according to claim 6, characterized in that the end member (11, 12) has a circular or polygonal cross-section. 7. The method according to any one of the preceding claims, characterized in that, in step (21) of forming the oscillating members (10a, 10b, 10c), the axial section (S1) of the second end (5d) of the body of the main body (6) is 1 / 3 to 1 / 5 of the axial section (S2) of the first end (5a). 8. The method according to any one of the preceding claims, characterized in that step (20) of forming the mechanical resonators (2b, 2c) and step (21) of forming at least one oscillating member (10a, 10b, 10c) are carried out by etching, particularly by deep reactive ion etching. 9. The method according to any one of the preceding claims, characterized in that step (21) of forming each oscillating member (10a, 10b, 10c) is carried out in the substrate (1) for at least one of the mechanical resonators (2b, 2c) in the group of mechanical resonators (2b, 2c). 10. The method according to any one of claims 1 to 8, characterized in that step (21) of forming the oscillating member (10a, 10b, 10c) is used to form a plurality of oscillating members (10a, 10b, 10c) around at least one mechanical resonator (2b, 2c) in the substrate (1).11. The method according to any one of the preceding claims, characterized in that the determining step (22) includes an estimation sub-step (23), in which at least one resonant frequency is estimated for each oscillating member (10a, 10b, 10c) associated with at least one mechanical resonator (2b, 2c) in the group of mechanical resonators (2b, 2c). 12. The method according to any one of the preceding claims, characterized in that the determining step (22) includes a defining sub-step (25), in which a structural characteristic is defined for each oscillating member (10a, 10b, 10c) that is identical in nature to the structural characteristics common to each of the formed mechanical resonators (2b, 2c), the defining sub-step (25) being performed by a processing unit connected to a means for modifying the formed mechanical resonators (2b, 2c), the processing unit executing an algorithm to calculate the structural characteristic of each oscillating member (10a, 10b, 10c) based on the estimated resonant frequency. 13. The method according to any one of the preceding claims, characterized in that the calculation step (26) includes a material thickness determination sub-step (27), in which the thickness (e) of material to be added to or removed from at least one dimension of each mechanical resonator (2b, 2c) associated with the oscillating member (10a, 10b, 10c) is determined based on structural characteristic values ​​determined for each oscillating member (10a, 10b, 10c). 14. The method according to any one of the preceding claims, characterized in that the oscillating member (10) is in the shape of a tuning fork. 15. The method according to any one of the preceding claims, characterized in that the structural characteristic is a stiffness characteristic. Claims 2 / 2 Page 3 CN 122226008 A Method for Manufacturing Mechanical Resonators Technical Field

[0001] The present invention relates to the field of manufacturing mechanical resonators, particularly in the field of watchmaking. More specifically, the present invention relates to a method for manufacturing a set of mechanical resonators wherein structural characteristics common to these resonators, such as stiffness, are within a predetermined numerical range. Background Art

[0002] In the prior art, methods commonly used to manufacture mechanical resonators such as watch hairsprings in substrates involve etching techniques such as laser etching, plasma etching, deep reactive ion etching (DRIE), or wet etching.

[0003] However, it has been found that using such methods often results in geometric deviations between all watch hairsprings formed on the same substrate with the same pattern.

[0004] To overcome these drawbacks, solutions have been proposed in the prior art, particularly patents EP 3181938 and EP 3181939, which describe methods for manufacturing hairsprings.

[0005] In patent EP3181938, the manufacturing method includes the following steps: a) forming a hairspring with a size larger than that required to obtain a hairspring with a predetermined stiffness; b) determining the stiffness of the hairspring formed in step a) by measuring the frequency of the hairspring connected to a balance wheel with a predetermined inertia; c) calculating the thickness of material to be removed to obtain a hairspring with a predetermined stiffness; and d) removing the calculated thickness of material from the hairspring formed in step a), wherein steps b), c) and d) can be repeated to further improve dimensional accuracy.

[0006] In patent EP 3181939, the manufacturing method includes the following steps: a) forming a hairspring with a size smaller than that required to obtain a hairspring with a predetermined stiffness; b) determining the stiffness of the hairspring formed in step a) by measuring the frequency of the hairspring connected to a balance wheel with a predetermined inertia; c) calculating the material thickness missing to obtain a hairspring with a predetermined stiffness; d) modifying the hairspring formed in step a) to compensate for the missing material thickness, wherein steps b), c), and d) can be repeated to further improve dimensional accuracy.

[0007] Such methods can be improved, especially to limit substrate contamination that may occur during the measurement steps.

[0008] In this case, it is obviously necessary to find a solution that can bring about such improvement. Summary of the Invention

[0009] The present invention aims to provide a method for manufacturing a set of mechanical resonators that meets the above-mentioned requirements.

[0010] The present invention also aims to improve the manufacturing accuracy of multiple sets of mechanical resonators, the average value of structural characteristics such as stiffness of the multiple sets of mechanical resonators being within a predetermined numerical range.

[0011] The present invention relates to a method for manufacturing a set of mechanical resonators, wherein the average value of the structural characteristics of the set of mechanical resonators is within a predetermined numerical range, the structural characteristics being common to each mechanical resonator in the set of mechanical resonators, the method comprising the following steps:

[0012] a) forming a mechanical resonator in a substrate, the size of the mechanical resonator being different from the size required to obtain the set of mechanical resonators with structural characteristics within the predetermined numerical range;

[0013] b) forming at least one oscillating member in the substrate, the at least one oscillating member being formed in an opening of the substrate, the oscillating member comprising a main body and two flexible arms, the main body being connected at one end to a fixing portion of the outer peripheral wall of the opening, the two flexible arms being connected to a second end of the main body via a connecting portion, the two flexible arms being parallel to the axis of symmetry of the main body and extending toward the fixing portion, the axial cross-section of the second end being smaller than the axial cross-section of the first end and larger than the axial cross-section of each of the flexible arms;

[0014] c) A determination step, in which a value related to the structural characteristics of the at least one oscillating member formed is determined;

[0015] d) A calculation step, in which a size correction value to be applied to the formed mechanical resonator is calculated based on the value determined for the structural characteristics;

[0016] e) A modification step, in which the size of the formed mechanical resonator is modified based on the calculated size correction value to obtain the set of mechanical resonators with structural characteristic values ​​within a predetermined range.

[0017] In other embodiments:

[0018] - In the step of forming the oscillating member, each of the flexible arms has a length adjustable according to a resonance measurement tolerance factor defined by at least one dimension of the flexible portion of the mechanical resonator associated with the at least one oscillating member;

[0019] - In the step of forming the oscillating member, each flexible arm is positioned at a first distance and a second distance from the body of the main body and the fixing portion of the outer peripheral wall of the opening, respectively, the first distance being greater than the second distance;

[0020] - In the step of forming the oscillating member, the thickness of each of the flexible arms is equal to or substantially equal to the thickness of the flexible portion of each mechanical resonator formed in the substrate;

[0021] - In the step of forming the oscillating member, the free end of each of the flexible arms is integrally formed with an end member, the mass of which is greater than the mass of the remainder of the body of the flexible arm;

[0022] - The end member has a circular or polygonal cross-section;

[0023] - In the step of forming the oscillating member, the axial cross section of the second end of the body of the main body is 1 / 3 to 1 / 5 of the axial cross section of the first end;

[0024] - The steps of forming the mechanical resonator and forming at least one oscillating member are carried out by etching, particularly by deep reactive ion etching;

[0025] - The step of forming each oscillating member is carried out in the substrate for at least one mechanical resonator in the group of mechanical resonators;

[0026] - The step of forming the oscillating member is used to form a plurality of oscillating members around at least one mechanical resonator in the substrate;

[0027] - The determining step includes an estimation sub-step in which at least one resonant frequency is estimated for each oscillating member associated with at least one mechanical resonator in the group of mechanical resonators;

[0028] - The determining step includes a definition sub-step in which a structural characteristic is defined for each oscillating member, the structural characteristic being the same as the structural characteristic common to each formed mechanical resonator, the definition sub-step being executed by a processing unit connected to a device for modifying the formed mechanical resonator, the processing unit executing an algorithm. So that the structural characteristics of each oscillating member can be calculated based on the estimated resonant frequency;

[0029] - The calculation step includes a material thickness determination sub-step, in which the thickness of material to be added to or removed from at least one dimension of each mechanical resonator associated with the oscillating member is determined based on the structural characteristic values ​​determined for each oscillating member;

[0030] - The oscillating member is in the shape of a tuning fork;

[0031] - The structural characteristics are stiffness characteristics.Specification 2 / 9 pages 5 CN 122226008 A Brief Description of the Drawings

[0032] Other features and advantages of the invention can be clearly discovered by reading the description of specific embodiments of the invention provided with reference to the accompanying drawings, which are provided as illustrative rather than limiting examples only, wherein:

[0033] FIG1 is a schematic diagram of a substrate according to an embodiment of the invention, the substrate including a set of mechanical resonators, all of which have been simultaneously formed, particularly by etching, in the substrate;

[0034] FIG2A is an enlarged view of an oscillating member in the form of a tuning fork according to an embodiment of the invention, the oscillating member being able to determine common characteristic values ​​of the mechanical resonators, the oscillating member and its resonators being contained in the substrate shown in FIG1;

[0035] FIG2B and FIG2C are variations of the oscillating member in FIG2A according to an embodiment of the invention, wherein the free end of the flexible arm of the oscillating member includes an end member, the mass of which is greater than the mass of the rest of the flexible arm;

[0036] FIG3 is a schematic cross-sectional view of the flexible portion of a resonator manufactured using the method according to an embodiment of the invention, the dimensions of which are necessary to ensure that the average value of the structural characteristics of the set of mechanical resonators is within a predetermined numerical range;

[0037] FIG4 is a schematic cross-sectional view of a flexible portion of a resonator formed in a substrate using the method according to an embodiment of the present invention, the size of which is larger than the size of the cross-section of the resonator shown in FIG3;

[0038] FIG5 is a schematic cross-sectional view of a flexible portion of a resonator formed in a substrate using the method according to an embodiment of the present invention, the size of which is smaller than the size of the cross-section of the resonator shown in FIG3;

[0039] FIG6 is a flowchart relating to a method for manufacturing a set of mechanical resonators according to an embodiment of the present invention, the average value of the structural characteristics of which is within a predetermined numerical range. Detailed Description

[0040] FIG6 shows a schematic diagram of a method for manufacturing a set of mechanical resonators 2a on a substrate 1 (referred to as a “wafer”) formed of a material. The substrate 1 may be a monocrystalline silicon substrate, but may also be a substrate made of other materials, such as polycrystalline silicon, amorphous silicon, other semiconductor materials, glass, ceramics, carbon, quartz, metals, alloys, or composite materials containing these materials. However, monocrystalline silicon is relatively insensitive to magnetic fields and is a cubic crystal with an isotropic coefficient of thermal expansion (α).

[0041] In this method, the mechanical resonators 2a, 2b, and 2c are elastically deformable components capable of being driven by oscillating motion. In other words, the mechanical resonators 2a, 2b, and 2c include a body composed of a flexible portion 3 and a connecting portion that is rigid relative to the flexible portion 3, the connecting portion allowing the mechanical resonators 2a, 2b, and 2c to be fixed to a shaft or spindle. Such mechanical resonators 2a, 2b, and 2c can be used in watches, especially in the mechanical regulators used to adjust the movement of a mechanical watch.In watches, the oscillation of such a mechanical resonator determines the timekeeping error of the movement. For example, many watches include a regulator comprising a hairspring that acts as a mechanical resonator, mounted on the balance wheel shaft and oscillating via an escapement. The natural frequency of the hairspring-balance wheel mechanism regulates the watch's speed. The hairspring comprises an elastic flexible band connected at one end to an inner stud and wound in a spiral to form multiple consecutive turns, the last turn extending into an attachment section for attachment, for example, to a fixed balance bridge via an outer stud. The inner stud is designed to be fixed to a pivot axis. Other known types of resonators are based, for example, on an oscillating rod or other mechanical components.

[0042] Thus, this method is capable of producing a set of mechanical resonators 2a whose average structural characteristics are within a predetermined range. In this method, the structural characteristics are common to all mechanical resonators 2a in the set. In other words, these mechanical resonators have the same structural characteristics. The structural characteristic can be the stiffness characteristic of the mechanical resonator 2a, especially the stiffness characteristic of its flexible part 3. In this case, the method makes it possible to select the specific set of mechanical resonators 2a from the plurality of mechanical resonators formed in the substrate 1. To this end, the method helps to generate a mapping map, which indicates the geometric dispersion between the dimensions of the plurality of mechanical resonators formed in the substrate, thereby indicating the dispersion between their common structural characteristics, and by correcting the selected set of mechanical resonators, the average value of their structural characteristics is within a predetermined value range. This method aims to ensure that the manufactured mechanical resonators 2a have extremely high dimensional accuracy, while at the same time ensuring that these mechanical resonators 2a have more accurate structural characteristics.

[0043] It should be noted that, in a preferred embodiment of the method, the mechanical resonators 2a, 2b, 2c can be a clock spring, and the structural characteristic can be the stiffness of the spring, especially the stiffness of its strip. In this case, the method can then be a method for manufacturing a set of clockwork springs 2a or a set of clockwork springs 2a in a substrate 1, wherein the average stiffness of each spring is within a predetermined range.

[0044] Referring to FIG1, a set of mechanical resonators 2a is formed in a substrate 1. In this set of mechanical resonators, each mechanical resonator 2a includes a flexible portion 3 and a rigid connecting portion for fixing the mechanical resonator to a shaft or spindle.

[0045] In the case where the mechanical resonator is a clockwork spring, the clockwork spring includes an inner stud for fixing it to a pivoting spindle.

[0046] This method is used in a system for manufacturing a set of mechanical resonators 2a, 2b, 2c in a substrate 1.The system includes, but is not exhaustive or limited to, a processing unit (e.g., a computer), means for forming mechanical resonators 2b, 2c and at least one oscillating member 10a, 10b, 10c in a substrate 1, and means for modifying the mechanical resonators 2b, 2c formed in the substrate 1.

[0047] The means for forming the mechanical resonators 2b, 2c and the oscillating members 10a, 10b, 10c can be used to implement microfabrication techniques in the substrate 1, such as photolithography, machining, and etching methods. In particular, methods such as deep reactive ion etching, laser etching, chemical etching, or etching using a focused ion beam can be employed.

[0048] The means for modifying the mechanical resonators 2b, 2c includes modules for determining the structural characteristics of the mechanical resonators 2b, 2c and modules for correcting the dimensions of the mechanical resonators 2b, 2c. The module for determining structural characteristics includes:

[0049] - a driving submodule for driving / releasing the mechanical oscillating motion of the bodies of the oscillating members 10a, 10b, 10c about their stable equilibrium positions;

[0050] - a measuring submodule for measuring the resonant frequency of the oscillating members 10a, 10b, 10c in the mechanical oscillating motion.

[0051] Regarding the size correction module for the mechanical resonators 2b, 2c, it includes a calculation submodule for calculating the corrections required for the mechanical resonators 2b, 2c and a correction submodule for correcting these mechanical resonators 2b, 2c using techniques that oxidize and then deoxidize these mechanical resonators, including thermal oxidation, electroplating growth, physical vapor deposition, chemical vapor deposition, atomic layer deposition, or any other additive process.

[0052] In this system, the processing unit is connected to the means for forming the mechanical resonators 2b, 2c and at least one oscillating member 10a, 10b, 10c in the substrate 1 and to the means for modifying the formed mechanical resonators 2b, 2c. Such a processing unit includes at least a processor and a storage element. The processing unit is capable of executing computer program instructions, for example, designed to guide / control both devices. Specifically, the processing unit ensures guidance / control of the drive submodule and the measurement submodule, and ensures computational / processing operations, in which at least one algorithm stored in the storage element is executed. The algorithm may include machine learning algorithms and / or mathematical formulas. The algorithm is capable of using predictive or simulation models to determine the structural characteristics, particularly the stiffness, of at least one oscillating component 10a, 10b, 10c, and to determine dimensional correction values ​​for the mechanical resonators 2b, 2c formed in the substrate 1.

[0053] The method includes a step 20 of forming mechanical resonators 2b and 2c, in which mechanical resonators 2b and 2c are formed in substrate 1 according to dimensions E2, E3, H2, H3, which are different from the dimensions E1 and H1 required for a group of mechanical resonators 2a to obtain an average value of structural characteristics within a predetermined range.

[0054] In this step 20, mechanical resonators 2b and 2c are formed in substrate 1. Preferably, these mechanical resonators 2b and 2c are formed simultaneously in substrate 1. The formation of these mechanical resonators 2b and 2c in substrate 1 is performed by a forming apparatus controlled by the processing unit of the system. It should be noted that these mechanical resonators 2b and 2c preferably have similar geometries or form similar structures.

[0055] Referring to Figures 1, 4, and 5, the mechanical resonators 2b and 2c formed in the substrate 1 have flexible portions 3, which have cross sections 4b and 4c, respectively, having dimensions E2, H2 and E3, H3. The cross sections 4b and 4c of the flexible portions 3 preferably have a polygonal shape similar to a hairspring strip, and are characterized in that the heights H2 and H3 and the thicknesses E2 and E3 of the cross sections 4b and 4c are different from the dimensions E1 and H1 required for a group of mechanical resonators 2a to obtain an average structural characteristic within a predetermined range. In other words, the dimensions E2, H2, E3, H3 of the cross sections 4b and 4c of the flexible portions 3 of each mechanical resonator 2b and 2c can be greater than or less than the dimensions E1 and H1 required for the cross sections 4a of the flexible portions of the manufactured mechanical resonators 2a to obtain an average structural characteristic within a predetermined range.

[0056] As described above, the substrate 1 is preferably made of doped or undoped silicon. The silicon can be monocrystalline, polycrystalline, or amorphous. Furthermore, the silicon can have orientations {1,1,1}, {-1,1,1}, {1,-1,1}, and {-1,-1,1}, where orientation is the most important factor for the Young's modulus of silicon.

[0057] It should be noted that during step 20, the formed mechanical resonators 2b and 2c may have:

[0058] - Dimensions E2 and H2, which are greater than the dimensions E1 and H1 required for a group of mechanical resonators 2a to obtain a set of mechanical resonators 2a with an average value of structural characteristics such as stiffness within a predetermined range, that is, the height H2 and / or the thickness E2 of the flexible part 3 are greater than the height H1 and / or the thickness E1 of the flexible part 3 of the mechanical resonator 2a with an average value of structural characteristics such as stiffness within a predetermined range;

[0059] - Dimensions E3 and H3, which are less than the dimensions E1 and H1 required for a group of mechanical resonators 2a to obtain a set of mechanical resonators 2a with an average value of structural characteristics such as stiffness within a predetermined range, that is, the height H3 and / or the thickness E3 of the flexible part 3 are less than the height H1 and / or the thickness E1 of the flexible part 3 of the mechanical resonator 2a with an average value of structural characteristics such as stiffness within a predetermined range.

[0060] The method further includes a step 21 of forming at least one oscillating member 10a, 10b, 10c, in which at least one oscillating member 10a, 10b, 10c is formed in a substrate 1, the oscillating member comprising a main body 6 and flexible arms / branches 7, 8, the flexible arms / branches 7, 8 being parallel to the axis of symmetry A of the main body 6.

[0061] Step 21 is performed on the same substrate 1 including the formed mechanical resonators 2b, 2c, preferably simultaneously with step 20 of forming these mechanical resonators 2b, 2c.

[0062] In step 21, at least one oscillating member 10a, 10b, 10c is fabricated in the substrate 1 for at least one of the group of mechanical resonators 2b, 2c. For example, oscillating members 10a, 10b, 10c can be fabricated for multiple mechanical resonators 2b, 2c arranged adjacent to each other or for each mechanical resonator 2b, 2c. Alternatively, multiple oscillating members 10a, 10b, 10c can be arranged around a single mechanical resonator 2b, 2c in the substrate 1, particularly in the adjacent region of the mechanical resonators 2b, 2c.

[0063] In step 21, the oscillating members 10a, 10b, 10c are constructed in an opening 9 in the substrate 1. The opening 9 is a through-hole formed within the thickness of the substrate 1, and the opening 9 includes an outer peripheral wall 13. The opening 9 defines a space in which the oscillating members 10a, 10b, 10c can freely perform guided / controlled mechanical oscillating motion.

[0064] As described above, the oscillating members 10a, 10b, 10c include a main body / shaft 6, which includes a preferably linear body, the first end 5a (also called the attachment end 5a) of which is connected to the outer peripheral wall 13 of the opening 9, particularly to a fixing portion 15 connected to the outer peripheral wall 13.The main body of the main stem 6 also includes a second end 5d, the axial section S1 of which is smaller than the axial section S2 of the first end 5a. The main body of the main stem 6 includes an axial section S4 between the first end 5a and the second end 5d, which is substantially constant. It should be noted that the axial section S1 of the second end 5d is preferably 1 / 3 to 1 / 5 of the axial section S2 of the first end 5a. The difference in axial section can reduce the stiffness of the main body of the main stem 6 at the second end 5d, and produce differences between the in-phase and out-of-phase modes of the flexible arms 7 and 8 when measuring the structural characteristics of the oscillating members 10a, 10b, and 10c, which are used to determine the relative values ​​of the structural characteristics in step 22 described below. It should be noted that the in-phase mode corresponds to the mode in which the flexible arms oscillate simultaneously in the same direction. In the out-of-phase mode, the oscillation phase difference of the flexible arms is 180 degrees. The two flexible arms move inward and outward simultaneously.

[0065] Furthermore, it should be noted that the difference in axial cross-section increases the stiffness of the main body 6 at the first end 5a, so as to decouple the oscillating motion of the flexible arms 7, 8 of the substrate 1 during this measurement.

[0066] The main body 6 is preferably rigid relative to the flexible arms 7, 8. More specifically, the main body 6 is connected to these flexible arms 7, 8 at its second end 5d by means of a connecting portion 14. The two flexible arms 7, 8 extend in a straight line within the opening 9 parallel to the axis of symmetry A and toward the fixing portion 15. It should be noted that the thickness of these flexible arms 7, 8 may be equal to or substantially equal to the thickness of the flexible portion 3 of the mechanical resonators 2a, 2b.

[0067] The axial cross-sections S3 of the two flexible arms 7, 8 are similar. Each axial cross-section S3 is defined relative to the axis of symmetry B of its respective flexible arm 7, 8, which is parallel to the axis of symmetry A of the main body 6. In this configuration, the axial cross sections S1 and S2 of the main body 6 are larger than the axial cross sections S3 of each flexible arm 7 and 8.

[0068] Referring to Figures 6 and 2A to 2B, in this step 21, these flexible arms 7 and 8 are designed to:

[0069] - be at a first distance D1 from the main body of the main body 6 of the oscillating members 10a, 10b, and 10c, which is preferably greater than or significantly greater than or substantially equal to the inter-turn distance of the mechanical resonators 2b and 2c (when the mechanical resonators 2b and 2c are springs or more specifically, hairsprings), and

[0070] - be at a first distance D2 from the fixing portion 15 of the outer peripheral wall 13 of the opening 9.

[0071] In this configuration, the first distance D1 is greater than the second distance D2.

[0072] It should be noted that the thickness Er of these flexible arms 7, 8 is preferably designed to be equal to or substantially equal to the thickness E2, E3 of the flexible portion 3 of each mechanical resonator 2b, 2c formed in the substrate 1.In other words, when the flexible portion 3 is a strip of a hairspring, the thickness Er of each flexible arm 7, 8 is equal to or substantially equal to the thickness E2, E3 of the flexible portion 3. For example, the thickness Er of these flexible arms 7, 8 can be between 10µm and 60µm, preferably 30µm.

[0073] In this step 21, these flexible arms 7, 8 are given a length L, which can be adjusted according to the required resonance measurement tolerance. This tolerance is defined based on at least one deviation of the dimensions E2, E3, H2, H3 of the flexible portion 3 of the mechanical resonators 2b, 2c associated with the oscillating members 10a, 10b, 10c. The value of this tolerance is equal to the frequency range in which the dimensional changes E2, E3, H2, H3 measured on the mechanical resonators 2b, 2c no longer require correction for stiffness differences in the mechanical resonators. This value defines a measurement range within which it is no longer necessary to determine the fine / sensitive dimensional changes of the flexible portion 3 of the formed mechanical resonators 2b and 2c. In other words, no adjustment is required below this tolerance. This value is specifically adapted to the dimensions of the flexible portion 3 of the mechanical resonators 2b and 2c to improve measurement sensitivity and the sensitivity to detection of changes in etching thickness. For example, the length is calculated such that when the frequency of the oscillating element changes by 10 Hz, a 10 nm dimensional change E2 and E3 of the mechanical resonator can be measured.

[0074] In this step, the process of calculating the lengths of the oscillating components 10a, 10b, and 10c includes:

[0075] - Defining a dimension Er, which is preferably equal to or substantially equal to the thicknesses E2, E3, H2, and H3 of the flexible portion 3 of each mechanical resonator 2b and 2c formed in the substrate 1;

[0076] - Defining a frequency variation that can be measured by a measurement system, thereby allowing for accurate frequency measurement, wherein the frequency variation is 2 to 10 times the standard deviation of the measurement;

[0077] - Defining the minimum dimensional variation of E2, E3, H2, and H3 of the mechanical resonators 2b and 2c to be measured; Specification 6 / 9 pages 9 CN 122226008 A

[0078] - Calculating the length L of the flexible arms 7 and 8, which is between 1 mm and 2 mm, such that the measurement of the frequency variation can lead to conclusions about the dimensional variation of E2, E3, H2, and H3 of the mechanical resonators 2b and 2c.

[0079] It should be noted that the shorter the length L of the flexible arms 7 and 8, the higher the measured resonant frequency will be, and the more sensitive the ratio between the addition or removal of uniformly thick material on the oscillating components 10a, 10b, and 10c and their resonant frequency will be.

[0080] In this step 21, it should be noted that the oscillating components 10a, 10b, and 10c are preferably arranged in the substrate 1 such that the positions of their flexible arms 7 and 8 enable the Young's modulus to reach its maximum or minimum value, especially when the substrate 1 is made of silicon.In fact, due to the anisotropy of silicon, this arrangement avoids significant changes in Young's modulus due to angles used to determine structural properties such as stiffness. Furthermore, the maximum Young's modulus should be prioritized to improve the accuracy of the correlation between stiffness and the measured frequency.

[0081] In the variations shown in Figures 2B and 2C, step 21, forming the oscillating members 10a, 10b, 10c, causes the free ends 5b, 5c of each flexible arm 7, 8 to be integrally formed with the end member 11, the mass of which is greater than the mass of the rest of the flexible arm 7, 8. In Figure 2B, the end member 11 has a polygonal cross-section; while in Figure 2C, the end member 12 has a circular cross-section. These end members 11, 12 allow for a reduction in the resonant frequency of the flexible arms 7, 8 while maintaining good sensitivity between the etch thickness Er and this frequency. In this case, the process of calculating the lengths of the oscillating components 10a, 10b, and 10c includes:

[0082] - Defining a dimension Er, which is preferably equal to or substantially equal to the thicknesses E2, E3, H2, and H3 of the flexible portion 3 of each mechanical resonator 2b and 2c formed in the substrate 1;

[0083] - Defining a frequency variation that can be measured by a measurement system, thereby allowing for accurate frequency measurement, wherein the frequency variation is between 2 and 10 times the standard deviation of the measurement; for example, the frequency variation may be 10 Hz;

[0084] - Defining the minimum dimensional variation of E2, E3, H2, and H3 of the mechanical resonators 2b and 2c to be measured; for example, for a measurable frequency variation of 10 Hz, the minimum dimensional variation may be 10 nm;

[0085] - Calculating the length L of the flexible arms 7 and 8, which is between 1 mm and 2 mm, such that the measurement of the frequency variation can lead to conclusions regarding the dimensional variations of E2, E3, H2, and H3 of the mechanical resonators 2b and 2c;

[0086] - Calculate the dimensions of the flexible arm ends to reduce the measurement frequency to a reasonable range for the measurement system.

[0087] Advantageously, these end members 11, 12 provide a larger surface area than the flexible arms 7, 8, which makes it easier to measure the resonant frequencies of the oscillating members 10b, 10c.

[0088] It should be understood that the oscillating members 10a, 10b, 10c designed during step 21 have a general shape of a tuning fork or are themselves tuning forks.

[0089] The oscillating members 10a, 10b, and 10c achieve optimal decoupling of the fixed-end effect from the resonant frequency. In fact, the fixed end has a significant influence on the resonant frequency during harmonic excitation. For the oscillating members 10a, 10b, and 10c, there is a clear decoupling between the fixed end and the resonant frequencies of the flexible arms 7 and 8. The correlation between the resonant frequency and structural characteristics such as stiffness is no longer related to the etching quality of the fixed end.

[0090] Furthermore, these oscillating components 10a, 10b, and 10c are configured such that their structural characteristics can be easily determined by the structural characteristic determination module in the mechanical resonator modification device. It should be noted that these oscillating components 10a, 10b, and 10c are configured to vibrate at a stable frequency, even if certain parameters change, particularly those related to the fixed end and manufacturing process. This stable frequency change depends only on one or more parameters / structural characteristics of the oscillating components 10a, 10b, and 10c. In this embodiment, the structural characteristic of the oscillating components 10a, 10b, and 10c that can significantly change the resonant frequency is preferably the thickness Er of the flexible arm. In addition to the thickness Er of the flexible arm, other characteristics, such as stiffness and the height h of the flexible arm, can also be used. In actual operation, the frequency is first measured, and then the dimensions under the etched mask are derived from it (arm thickness = arm dimension on the DRIE mask - etched dimension). The stiffness of the tuning fork cannot be obtained directly. Therefore, after inferring the thickness (the dimension under the etching mask), the stiffness of the wire can be calculated so that necessary adjustments can be made.

[0091] The method then includes a determination step 22, in which the structural characteristics of at least one oscillating member 10a, 10b, 10c associated with at least one mechanical resonator 2b, 2c formed in the substrate 1 are determined. The determination step 22 includes an estimation sub-step 23, in which at least one resonant frequency of at least one oscillating member 10a, 10b, 10c is estimated. In the estimation sub-step 23, the at least one oscillating member 10a, 10b, 10c is subjected to mechanical oscillating motion about its stable equilibrium position. During this motion, in a measurement phase 24, the resonant frequency of the oscillating member 10a, 10b, 10c is determined.

[0092] The measurement phase 24 is implemented by a measurement sub-module of the structural characteristic determination module in the modification device for the mechanical resonators 2b, 2c. In a variant of the oscillating members 10b, 10c provided with flexible arms 7, 8 (each flexible arm including end members 11, 12), the measurement submodule includes a velocity meter that can be focused on the end members 11, 12 of the flexible arms 7, 8 that are oscillating. In this configuration, measurements can be taken out of plane, with the velocity meter axis perpendicular to the wafer plane.

[0093] It should be noted that when multiple oscillating members 10a, 10b, 10c are associated with a single mechanical resonator 2a, 2c, the resonant frequencies of all these oscillating members 10a, 10b, 10c are measured, and then the average of these frequencies is calculated to correspond to the resonant frequencies associated with the combination of oscillating members 10a, 10b, 10c.Alternatively, the measured resonant frequency of the combination can be the resonant frequency of only one of its oscillating elements 10a, 10b, 10c, or it can be the resonant frequency of a sample of its oscillating elements 10a, 10b, 10c.

[0094] Once the resonant frequency has been estimated, step 22 includes a definition sub-step 25 in which a structural characteristic, such as stiffness, of the at least one oscillating element 10a, 10b, 10c is defined. In this definition sub-step 25, the processing unit executes an algorithm for calculating the structural characteristic based on the estimated resonant frequency of the at least one oscillating element 10a, 10b, 10c.

[0095] The method then includes a calculation step 26 in which a dimensional correction value to be applied to each of the mechanical resonators 2b, 2c in the group of mechanical resonators is calculated based on the structural characteristics determined for the related system 3. In calculation step 26, the dimensional correction amount to be applied to the mechanical resonators 2b, 2c is determined.

[0096] To this end, the calculation step 26 includes a material thickness determination sub-step 27, in which, based on the determined structural characteristics, the thickness e of the material to be added to or removed from at least one dimension of the mechanical resonators 2b, 2c formed in step 20 is determined to obtain a set of mechanical resonators 2a whose average structural characteristics are within a predetermined numerical range.

[0097] This dimensional correction actually corresponds to the thickness e of the material removed from or added to the mechanical resonators 2b, 2c, in order to change at least one of their dimensions E2, H2, E3, H3, namely:

[0098] - only the heights H2, H3 of the flexible portion 3, or

[0099] - only the thicknesses E2, E3 of the flexible portion 3, or

[0100] - both the heights H2, H3 and the thicknesses E2, E3.

[0101] The dimensional correction can be performed on one or more individual segments of the flexible portion 3 of the mechanical resonators 2b and 2c, or on the entire length of the flexible portion 3.

[0102] Therefore, by determining the dimensional correction value, the material thickness determination sub-step 27 can participate in forming the geometry of the mechanical resonators 2b and 2c, so that their structural characteristic values ​​are within a predetermined range.

[0103] Then, the method includes a modification step 28, in which the dimensions E2, E3, H2, and H3 of the mechanical resonators 2b and 2c are modified based on the calculated dimensional correction value to obtain a set of mechanical resonators 2a whose average structural characteristics are within a predetermined range.

[0104] In this case, if the dimensions E2 and H2 of the mechanical resonator 2b are greater than the dimensions E1 and H1 required to bring the average structural characteristics of the group of mechanical resonators 2a within a predetermined range, then the modification step 28 includes a sub-step 29 in which material is removed according to the calculated thickness e of the material to be removed. The material removal can be carried out using an oxidation-deoxidation process for these mechanical resonators 2b that is well known in the art. The purpose of this sub-step 29 is to reduce the dimensions of the cross section 4b of the flexible portion 3 of the mechanical resonator 2b over a given length or the entire length of the flexible portion 3.

[0105] If the dimensions E3 and H3 of the mechanical resonator 2c are less than the dimensions E1 and H1 required to bring the average structural characteristics of the group of mechanical resonators 2a within a predetermined range, then the modification step 28 includes a sub-step 30 in which material is added according to the calculated thickness e of the material to be added. The addition of materials can be performed using methods known in the prior art, such as thermal oxidation, electroplating growth, physical vapor deposition, chemical vapor deposition, atomic layer deposition, or any other additive process. The purpose of this sub-step 30 is to increase the dimensions E3, H3 of the cross-section 4c of the flexible portion 3 of the mechanical resonator 2c over a given length or the entire length of the flexible portion 3.

[0106] Therefore, this method is able to utilize the high precision provided by the reference stiffness indication system to correct dimensional errors in resonators manufactured using methods such as photolithography and / or DRIE technology.

[0107] Terminology

[0108] 1. A substrate including at least one mechanical resonator

[0109] 2a. A manufactured mechanical resonator

[0110] 2b. A mechanical resonator formed in a substrate and having a cross-sectional dimension larger than that of the manufactured mechanical resonator

[0111] 2c. A mechanical resonator formed in a substrate and having a cross-sectional dimension smaller than that of the manufactured mechanical resonator

[0112] 3. A flexible portion of a mechanical resonator

[0113] 4a. A cross-section of a manufactured mechanical resonator

[0114] 4b. A cross-section of a mechanical resonator with a dimension larger than that of the manufactured mechanical resonator

[0115] 4c. A cross-section of a mechanical resonator with a dimension smaller than that of the manufactured mechanical resonator

[0116] 5a. An attachment end of an oscillating member

[0117] 5b, 5c. A free end of an oscillating member

[0118] 6. A main body / shaft portion of an oscillating member

[0119] 7. 8. First flexible arm of the oscillating member

[0120] 9. Second flexible arm of the oscillating member

[0121] 10. Opening of the oscillating member

[0122] 11. Oscillating member

[0123] 12. End member with polygonal cross section

[0124] 13. End member with circular cross section

[0125] 14. Outer peripheral wall of the opening

[0126] 15. Connecting part that connects the flexible arm to the main body of the oscillating member

[0127] 16. Fixing part on the outer peripheral wall of the opening of the oscillating member.Instruction manual 9 / 9 pages 12 CN 122226008 A Figure 1 Figure 2A Instruction manual drawings 1 / 4 pages 13 CN 122226008 A Figure 2B Figure 2C Instruction manual drawings 2 / 4 pages 14 CN 122226008 A Figure 3 Figure 4 Figure 5 Instruction manual drawings 3 / 4 pages 15 CN 122226008 A Figure 6 Instruction manual drawings 4 / 4 pages 16 CN 122226008 A One aspect of the invention relates to a method for manufacturing a batch of mechanical resonators (2a) whose structural characteristics have an average within a predetermined range of values, the method comprising the formation (21) in a wafer (1) of mechanical resonators (2b, 2c) and oscillating elements (10a, 10b, 10c) and the calculation (26) of dimensional corrections to be applied to the resonators (2b, 2c) formed, from the determined value relating to the structural characteristic and then a modification (28) of the dimensions of the resonators (2b, 2c) formed, from the dimensional corrections calculated to obtain the batch of resonators (2a) whose values ​​of the structural characteristics are within the predetermined range of values..

Claims

1. A method for manufacturing a set of mechanical resonators (2a) having an average structural characteristic within a predetermined range, said structural characteristic being common to each of the mechanical resonators (2a) in the set, said method comprising the following steps: a) Step (20) of forming mechanical resonators (2b, 2c) in substrate (1), wherein the size of the mechanical resonators (2b, 2c) is different from the size required to obtain the set of mechanical resonators (2a) with structural characteristics within the predetermined numerical range; (b) Step (21) forming at least one oscillating member (10a, 10b, 10c) in the substrate (1), the at least one oscillating member (10a, 10b, 10c) being formed in the opening (9) of the substrate (1), the oscillating member (10a, 10b, 10c) being composed of a main body (6) and two flexible arms (7, 8), the body of the main body (6) being connected at the first end (5a) to the fixing part (15) of the outer peripheral wall (13) of the opening (9), the two flexible arms being connected to the second end (5d) of the main body (6) through the connecting part (14), the two flexible arms (7, 8) being parallel to the axis of symmetry (A) of the main body (6) and extending toward the fixing part (15), the axial section (S1) of the second end (5d) being smaller than the axial section (S2) of the first end (5a) and larger than the axial section (S3) of each of the flexible arms (7, 8); c) Determine step (22), in which a value related to the structural characteristics of the formed at least one oscillating member (10a, 10b, 10c) is determined; d) Calculation step (26), in which the size correction values ​​to be applied to the formed mechanical resonators (2b, 2c) are calculated based on the values ​​determined for the structural characteristics; e) Modification step (28), in which the dimensions of the formed mechanical resonators (2b, 2c) are modified based on the calculated dimension correction values ​​to obtain the set of mechanical resonators (2a) with structural characteristic values ​​within a predetermined range.

2. The method according to claim 1, characterized in that, In step (21) of forming the oscillating components (10a, 10b, 10c), each of the flexible arms (7, 8) is given a length (L) that can be adjusted according to a resonance measurement tolerance factor defined by at least one dimension (E2, E3, H2, H3) of the flexible portion (3) of the mechanical resonator (2b, 2c) associated with the at least one oscillating component (10a, 10b, 10c).

3. The method according to any one of the preceding claims, characterized in that, In step (21) of forming the oscillating components (10a, 10b, 10c), each flexible arm is positioned at a first distance (D1) and a second distance (D2) from the body of the main body (6) and the fixing part (15) of the outer peripheral wall (13) of the opening (9), respectively. The first distance (D1) is greater than the second distance (D2).

4. The method according to any one of the preceding claims, characterized in that, In step (21) of forming the oscillating components (10a, 10b, 10c), the thickness (Er) of each of the flexible arms (7, 8) is made equal to or substantially equal to the thickness of the flexible portion (3) of each mechanical resonator (2b, 2c) formed in the substrate (1).

5. The method according to any one of the preceding claims, characterized in that, In step (21) of forming the oscillating components (10a, 10b, 10c), the free end (5b, 5c) of each of the flexible arms (7, 8) is integrally formed with the end member (11, 12), the mass of which is greater than the mass of the rest of the body of the flexible arm (7, 8).

6. The method according to claim 6, characterized in that, The end members (11, 12) have a circular or polygonal cross-section.

7. The method according to any one of the preceding claims, characterized in that, In step (21) of forming the oscillating member (10a, 10b, 10c), the axial section (S1) of the second end (5d) of the body of the main stem (6) is 1 / 3 to 1 / 5 of the axial section (S2) of the first end (5a).

8. The method according to any one of the preceding claims, characterized in that, The steps (20) of forming the mechanical resonator (2b, 2c) and (21) of forming at least one oscillating element (10a, 10b, 10c) are carried out by etching, particularly by deep reactive ion etching.

9. The method according to any one of the preceding claims, characterized in that, Step (21) of forming each oscillating element (10a, 10b, 10c) is carried out in the substrate (1) for at least one of the mechanical resonators (2b, 2c) in the group of mechanical resonators (2b, 2c).

10. The method according to any one of claims 1 to 8, characterized in that, Step (21) of forming oscillating members (10a, 10b, 10c) is used to form a plurality of oscillating members (10a, 10b, 10c) around at least one mechanical resonator (2b, 2c) in the substrate (1).

11. The method according to any one of the preceding claims, characterized in that, The determining step (22) includes an estimation sub-step (23), in which at least one resonant frequency is estimated for each oscillating element (10a, 10b, 10c) associated with at least one mechanical resonator (2b, 2c) in the group of mechanical resonators (2b, 2c).

12. The method according to any one of the preceding claims, characterized in that, The determining step (22) includes a defining sub-step (25) in which a structural characteristic is defined for each oscillating element (10a, 10b, 10c) that is the same as the structural characteristic shared by each of the formed mechanical resonators (2b, 2c). The defining sub-step (25) is performed by a processing unit connected to a device for modifying the formed mechanical resonators (2b, 2c). The processing unit executes an algorithm to calculate the structural characteristic of each oscillating element (10a, 10b, 10c) based on the estimated resonant frequency.

13. The method according to any one of the preceding claims, characterized in that, The calculation step (26) includes a material thickness determination sub-step (27), in which the thickness (e) of the material to be added to or removed from at least one dimension of each mechanical resonator (2b, 2c) associated with each oscillating member (10a, 10b, 10c) is determined based on the structural characteristic values ​​determined for each oscillating member (10a, 10b, 10c).

14. The method according to any one of the preceding claims, characterized in that, The oscillating component (10) is in the shape of a tuning fork.

15. The method according to any one of the preceding claims, characterized in that, The structural characteristic mentioned is stiffness characteristic.

Images