Manufacturing method for mechanical resonators

Abstract

To provide a manufacturing method for mechanical resonators. [Solution] One aspect of the present invention relates to a method for manufacturing a set of mechanical resonators (2a) having structural characteristics whose average values ​​fall within a predetermined range, the method comprising the steps of (20) forming mechanical resonators (2b, 2c) and at least one vibrating member (10a, 10b, 10c) within a plate (1), and (28) correcting the dimensions of the formed resonators (2b, 2c) based on dimensional corrections calculated to obtain a set of resonators (2a) having structural characteristic values ​​that fall within a predetermined range.

Description

Technical Field

[0001] The present invention relates to the field of manufacturing mechanical resonators, particularly in the field of watches. More particularly, the present invention relates to a method for manufacturing a set of mechanical resonators, in which structural features such as stiffness, which are common to these resonators, are within a predetermined value range.

Background Art

[0002] In the prior art, it is common to use a method for manufacturing a mechanical resonator such as a hairspring in a plate, and this method includes engraving techniques such as laser engraving, plasma engraving, deep reactive ion etching (DRIE) or wet engraving.

[0003] However, it has been found that using such a method conventionally results in geometric dissipation between hairsprings for watches that are all formed on the same plate with the same pattern.

[0004] To improve these drawbacks, solutions have been proposed in the prior art, particularly in European Patent Nos. 3181938 and 3181939, which describe methods for manufacturing hairsprings.

[0005] In European Patent No. 3181938, the manufacturing method includes: a) forming a hairspring with dimensions larger than those required to obtain a hairspring having a predetermined stiffness; b) determining the stiffness of the hairspring formed in step a) by measuring the frequency of the hairspring coupled to a template having a predetermined inertia; c) calculating the thickness of the material to be removed to obtain a hairspring having a predetermined stiffness; and d) removing the calculated thickness of the material from the hairspring formed in step a), and steps b), c) and d) can be repeated to further improve the quality of the dimensions.

[0006] European Patent No. 3181939 provides a manufacturing method comprising: a) forming a hairspring with dimensions smaller than those 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 coupled to a balance wheel having a predetermined inertia; c) calculating the thickness of missing material to obtain a hairspring with a predetermined stiffness; and d) modifying the hairspring formed in step a) to compensate for the missing thickness of material, wherein steps b), c), and d) can be repeated to further improve the quality of dimensions.

[0007] Such methods can be improved, in particular, to limit the contamination of the plates that may occur during the measurement steps.

[0008] Under these circumstances, it is clear that we need to find solutions that will bring about such improvements. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] European Patent No. 3181938 [Patent Document 2] European Patent No. 3181939 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] The present invention aims to provide a method for manufacturing a set of mechanical resonators that satisfy the above requirements.

[0011] The present invention also aims to improve the accuracy in the manufacture of a set of mechanical resonators having structural characteristics such as rigidity, in which the average value falls within a predetermined range. [Means for solving the problem]

[0012] The present invention relates to a method for manufacturing a set of mechanical resonators having structural characteristics such that the average value falls within a predetermined range, wherein the structural characteristics are common to each resonator in the set, and the method is as follows: a) A step of forming a mechanical resonator within the plate, wherein the mechanical resonator has dimensions different from those required to obtain a set of mechanical resonators having structural features that fall within a predetermined range; b) A step of forming at least one vibrating member in an opening made in the plate, wherein the member comprises a trunk having a body joined at a first end to a fixed portion of the wall in the opening, and two flexible arms joined at a second end of the trunk by a connecting portion, the arms being parallel to the axis of symmetry of the trunk and extending toward the portion of the wall opposite the fixed portion, and the body of the trunk having a portion between the first end and the second end having an axial cross-section smaller than the axial cross-sections of the first end and the second end, respectively, c) A step of determining a value for the structural characteristics of the formed at least one vibrating member, d) A step of calculating the dimensional correction to be applied to the formed resonator based on the values ​​determined regarding the structural characteristics, e) A step of correcting the dimensions of the formed resonators based on dimensional corrections calculated to obtain a set of resonators having structural characteristic values ​​that fall within a predetermined range. Includes.

[0013] In other embodiments, - The forming step specifies that the axial cross-section is larger than the axial cross-section of each arm. - The step of forming the vibrating member specifies that each arm is designed to be of a certain length, which can be adjusted according to a resonance measurement tolerance, the resonance measurement tolerance is defined by the dimensions of at least one of the dimensions of the flexible portion of the resonator associated with the at least one vibrating member. - The step of forming the vibrating member is designed such that one arm is spaced a first distance from the other arm, and the free ends of each of these arms are spaced a second distance from the opposite side of the fixed portion, wherein the first distance is greater than the second distance. - The step of forming the vibrating member specifies that each arm is designed to be the same thickness as, or substantially the same thickness as, the flexible portion of each resonator formed within the plate. - The step of forming the vibrating member is to specify that each arm is designed with a free end made from the same material as the end member, and that the end member has a mass greater than the rest of the body of the arm. - The end members have a circular or polygonal cross-section. - The step of forming the vibrating member specifies that the trunk body is designed with a cross-section between one-half and one-fifth of the axial cross-section of the first end and the second end, respectively. - The step of forming the mechanical resonator and at least one vibrating member is carried out by engraving, in particular by deep reactive ion etching. - The step of forming each vibrating member is performed within the plate for at least one resonator in the set of mechanical resonators. - The forming step specifies that in the plate, multiple vibrating members are generated, each surrounding at least one resonator. - The determination step includes a substep of estimating at least one resonant frequency for each vibrating member associated with at least one resonator in the set of resonators. - The determination step includes a substep for each vibrating member that defines structural features which are the same as the structural features common to each formed resonator, the substep being performed by a processing unit, which is connected to a device that modifies the formed resonators and runs an algorithm that calculates these structural features for each vibrating member based on the estimated resonant frequencies. - The calculation step includes a sub-step of determining the thickness (e) of the material to be added to or removed from at least one dimension of each resonator associated with the vibrating member, based on the values determined for the structural characteristics of each vibrating member. - The vibrating member is in the shape of a tuning fork. - The structural characteristic is a rigidity characteristic.

[0014] Other features and advantages of the present invention will become more apparent from the accompanying drawings upon reading the following description of specific embodiments of the present invention, which are provided by way of illustration only and not limitation.

Brief Description of the Drawings

[0015] [Figure 1] Schematic view of a plate comprising a set of mechanical resonators according to an embodiment of the present invention, all the mechanical resonators being formed simultaneously in this plate, in particular by engraving. [Figure 2A] Enlarged view of a vibrating member in the form of a tuning fork according to an embodiment of the present invention, the vibrating member making it possible to determine a value of a characteristic common to the mechanical resonators, and this vibrating member, together with these resonators, is included in the plate shown in FIG. 1. [Figure 2B] View of a deformed form of the vibrating member of FIG. 2A according to an embodiment of the present invention, the free end of the arm of this member comprising an end member having a mass greater than the remaining mass of the body of this arm. [Figure 2C] View of a deformed form of the vibrating member of FIG. 2A according to an embodiment of the present invention, the free end of the arm of this member comprising an end member having a mass greater than the remaining mass of the body of this arm. [Figure 3] Schematic view of a cross-section of the flexible part of a resonator manufactured using the method according to an embodiment of the present invention, the cross-section having the dimensions necessary to obtain a set of mechanical resonators having structural characteristics whose average value is included within a predetermined value range. [Figure 4]Schematic cross - section of a flexible part of a resonator formed in a plate using the method according to an embodiment of the present invention, the cross - section having dimensions larger than those of the cross - section of the fabricated resonator shown in FIG. 3. [Figure 5] Schematic cross - section of a flexible part of a resonator formed in a plate using the method according to an embodiment of the present invention, the cross - section having dimensions smaller than those of the cross - section of the fabricated resonator shown in FIG. 3. [Figure 6] Flowchart related to a method of manufacturing a set of mechanical resonators having structural features with an average value within a predetermined value range according to an embodiment of the present invention.

Mode for Carrying Out the Invention

[0016] FIG. 6 shows a schematic view of a method of manufacturing a set of mechanical resonators 2a in a material plate 1 (referred to as a wafer). This plate 1 can be a single - crystal silicon plate, but plates made from other materials can also be used, for example, plates made from polycrystalline or amorphous silicon, other semiconductor materials, glass, ceramics, carbon, quartz, metals or alloys, or plates made from composites containing these materials. However, single - crystal silicon has relatively low sensitivity to magnetic fields, belongs to the cubic crystal system, and has an isotropic coefficient of thermal expansion (alpha).

[0017] In this method, the mechanical resonators 2a, 2b, and 2c are elastically deformable components that can be driven by oscillating motion. In other words, the resonators 2a, 2b, and 2c comprise a body consisting of a flexible part 3 and a connecting part that is rigid relative to the flexible part 3, the connecting part allowing the resonators 2a, 2b, and 2c to be fixed to an axis or arbor. Such mechanical resonators 2a, 2b, and 2c can be used in clocks, particularly in mechanical governors that regulate the movement of a mechanical clock. In a clock, the oscillation of such a resonator determines the speed of the movement. Many clocks have a governor that, for example, has a hairspring as a resonator, the resonator mounted on the axis of the balance wheel, and the oscillation is set by the escapement. The natural frequency of the balance wheel with the hairspring regulates the clock. Such a watch hairspring comprises an elastic flexible element, which is connected at one end to a hairspring ball and wound helically to form multiple successive windings, the last winding being stretched by, for example, the balance staff of the hairspring by a mounting section designed to be attached to a fixed balance bar. Such a hairspring ball is designed to be fixed to a pivot arbor. Other known types of resonators are based, for example, on an oscillating rod or other mechanical components.

[0018] Therefore, this method enables the manufacture of this set of resonators 2a having structural characteristics in which the average value falls within a predetermined range. In this method, this characteristic is common to all resonators 2a in this set. In other words, these resonators have the same structural characteristics. This structural characteristic can be the rigidity characteristic of this resonator 2a, in particular the flexible portion 3 of the resonator 2a. In this case, the method enables the selection of this particular set of resonators 2a from among a plurality of resonators formed in this plate 1. To this end, the method thus helps to create a map showing the geometric dispersion between the dimensions of the resonators formed in the plate, and by extension, the dispersion between their common structural characteristics, and corrects the selected set of resonators so that they have structural characteristics in which the average value falls within a predetermined range. Such a method aims to ensure fairly high dimensional accuracy of the manufactured resonators 2a and incidentally guarantee more precise structural characteristics of these resonators 2a.

[0019] In a preferred embodiment of this method, the resonators 2a, 2b, and 2c may be watch hairsprings, and it should be noted that the structural feature may be the rigidity of the hairspring, particularly its blades. In this case, the method may be a method for manufacturing a set or assembly of watch hairsprings 2a within plate 1, and the rigidity has an average value that falls within a predetermined range.

[0020] Referring to Figure 1, the set of mechanical resonators 2b and 2c is formed within the material plate 1. Thus, in this set, each resonator 2b and 2c is provided with a flexible portion 3, the flexible portion 3 is provided with a rigid connector that fixes the resonator to the shaft or arbor.

[0021] In the context where these resonators 2b and 2c are hairsprings, the hairsprings are equipped with hairspring beads that fix the hairsprings to the pivot arbor.

[0022] Such a method is used in a system for manufacturing a set of resonators 2a, 2b, and 2c within a plate 1. This system comprises, but is not exhaustive, a processing unit such as a computer, an apparatus for forming the resonators 2b, 2c and at least one vibrating member 10a, 10b, and 10c within the plate 1, and an apparatus for modifying the resonators 2b and 2c formed within the plate 1.

[0023] The apparatus for forming the resonators 2b, 2c and the vibrating members 10a, 10b, 10c within the plate 1 can be used to implement microfabrication techniques such as photolithography, machining, and engraving within the plate 1. In particular, these techniques include deep reactive ion etching, laser engraving, chemical engraving, or engraving using a focused ion beam.

[0024] The apparatus for modifying resonators 2b and 2c comprises a module for determining structural characteristics and a module for correcting the dimensions of resonators 2b and 2c. This module for determining structural characteristics is: - In the main body of the vibrating members 10a, 10b, and 10c, a sub-module is provided to drive / release the mechanical oscillation motion around its stable equilibrium position. - A sub-module for measuring the resonant frequencies of vibrating members 10a, 10b, and 10c during mechanical oscillation motion. It is equipped with.

[0025] With respect to the dimensional correction module for resonators 2b and 2c, the dimensional correction module comprises a submodule for calculating the correction to be made to resonators 2b and 2c, and a submodule for correcting these resonators 2b and 2c, using techniques for oxidizing and then deoxidizing these resonators, thermal oxidation, galvanic growth, physical vapor deposition, chemical vapor deposition, atomic layer deposition, or any other addition method.

[0026] In this system, the processing unit is connected to an apparatus for forming resonators 2b, 2c and at least one vibrating member 10a, 10b, 10c within the plate 1, and an apparatus for modifying the formed resonators 2b, 2c. Such a processing unit comprises at least one processor and a memory element. The unit is capable of executing instructions to implement a computer program intended to guide / control these two apparatuses, for example. In particular, such a unit can ensure guidance / control of the drive submodule and the measurement submodule, as well as computational / processing operations in which at least one algorithm stored in the memory element is implemented. This algorithm may include machine learning algorithms and / or mathematical formulas. This algorithm allows for the use of a predictive or simulation model to determine the structural characteristics of at least one vibrating member 10a, 10b, 10c, particularly its stiffness, and for correcting the dimensions to be made to the resonators 2b, 2c formed within the plate 1.

[0027] Such a method includes step 20 of forming mechanical resonators 2b, 2c within plate 1 according to dimensions E2, E3, H2, H3, where dimensions E2, E3, H2, H3 are different from dimensions E1, H1 required to obtain a set of mechanical resonators 2a having structural characteristics in which the average value falls within a predetermined range.

[0028] In step 20, the resonators 2b and 2c are formed within the plate 1. Preferably, these resonators 2b and 2c are formed simultaneously within the plate 1. The formation of these resonators 2b and 2c within the plate 1 is carried out by a forming apparatus controlled by the system's processing unit. It should be noted that these resonators 2b and 2c preferably have similar shapes or form similar patterns.

[0029] Referring to Figures 1, 4, and 5, these mechanical resonators 2b, 2c formed within the plate 1 have a flexible section 3 having cross-sections 4b, 4c, where cross-sections 4b, 4c have dimensions E2, H2, E3, H3. Preferably, the cross-sections 4b, 4c of this flexible section 3 have a polygonal shape similar to that of a hairspring blade, and are characterized by heights H1, H2, H3 and thicknesses E1, E2, E3 of these cross-sections 4a, 4b, 4c, which are different from the dimensions E1, H1 required to obtain a set of mechanical resonators 2a having structural features in which the average values ​​fall within a predetermined range. In other words, the flexible portion 3 of each resonator 2b, 2c may have cross-sections 4b, 4c having dimensions E2, H2, E3, H3, where dimensions E2, H2, E3, H3 are greater than or less than the required dimensions E1, H1 for the cross-section 4a of this flexible portion of resonator 2a, which is manufactured to allow for structural features in which the average values ​​fall within a predetermined range.

[0030] As mentioned above, the plate 1 is preferably made from doped silicon or undoped silicon. This silicon can be single crystal, polycrystalline, or amorphous silicon. Furthermore, this silicon may have the directions {1,1,1}, {-1,1,1}, {1,-1,1}, and {-1,-1,1}, in which the Young model of silicon is most important.

[0031] It should be noted that during this forming step 20, the mechanical resonators 2b and 2c that are formed may have the following characteristics: - Dimensions E2 and H2 that are greater than the dimensions E1 and H1 required to obtain a set of mechanical resonators 2a having structural characteristics such as rigidity whose average value falls within a predetermined range, i.e., the height H2 of the flexible part 3 and the thickness E2 of the flexible part 3, are greater than the height H1 and / or thickness E1 of the flexible part 3 of the mechanical resonator 2a having structural characteristics such as rigidity whose average value falls within a predetermined range. -The dimensions E3, H3, i.e., the height H3 and thickness E3 of the flexible part 3 are smaller than the dimensions E1, H1 required to obtain a set of mechanical resonators 2a having structural characteristics such as rigidity whose average value falls within a predetermined range, and are smaller than the height H1 and / or thickness E1 of the flexible part 3 of a mechanical resonator 2a having structural characteristics such as rigidity whose average value falls within a predetermined range.

[0032] The method also includes step 21 of forming at least one vibrating member 10a, 10b, 10c within the plate 1, the vibrating member comprising a trunk 6 and flexible arms / branch portions 7, 8, the arms 7, 8 being parallel to the axis of symmetry A of the trunk 6.

[0033] This step 21 is preferably performed simultaneously with step 20, in which these resonators 2b, 2c are formed, within the same plate 1 comprising the mechanically formed resonators 2b, 2c.

[0034] In step 21, at least one vibrating member 10a, 10b, 10c is fabricated within plate 1 for at least one resonator 2b, 2c in the set of mechanical resonators 2b, 2c. For example, vibrating members 10a, 10b, 10c may be fabricated for several resonators 2b, 2b located in their immediate vicinity, or for each resonator 2b, 2c. Alternatively, several vibrating members 10a, 10b, 10c may be placed within plate 1 around a single resonator 2b, 2c, particularly in the immediate vicinity of this resonator 2b, 2c.

[0035] In step 21, the members 10a, 10b, and 10c are designed within an opening 9 provided within the plate 1. Such an opening 9 is a through-hole, which is made of the thickness of the plate 1 and includes a peripheral wall 13. Such an opening 9 defines a space in which the vibrating members 10a, 10b, and 10c can freely perform guided / controlled mechanical oscillation motion.

[0036] As described above, the vibrating members 10a, 10b, and 10c are preferably composed of a trunk / arbor 6 having a straight body, the body being joined at one end 5a, also called the mounting end 5a, to the peripheral wall 13 of the opening 9, particularly to the fixing portion 15 of the wall 13. The trunk body 6 also includes a second end 5d having an axial cross section S1, the axial cross section S1 being substantially equal to or the same as the axial cross section S2 of the first end 5a. The body of the trunk 6 includes a portion between these first end 5a and second end 5d, the portion having an axial cross section S4 that is smaller than the axial cross sections S2 and S1 of the first end 5a and the second end 5d, respectively. It should be noted that this cross section S4 is preferably between half and one-fifth of these axial cross sections S2 and S1.

[0037] This difference in cross-section reduces the rigidity of the trunk body 6 in this section, allowing arms 7 and 8 to create a difference between in-phase and out-of-phase modes when measuring the structural characteristics of the vibrating members 10a, 10b, and 10c, and this measurement is used in step 22 to determine the relative values ​​of these structural characteristics, as described below.

[0038] Note that the in-phase mode corresponds to a mode in which arms 7 and 8 oscillate simultaneously in the same direction. In the out-of-phase mode, arms 7 and 8 oscillate with a 180-degree phase difference. Both arms move simultaneously inward and outward.

[0039] Furthermore, it should be noted that the difference in cross-section increases the rigidity of the trunk body 6 at the first end 5a and the second end 5d, so as to isolate the oscillating motion of the arms 7 and 8 of plate 1 when this measurement is taken.

[0040] The body of the trunk 6 is preferably rigid with respect to the flexible arms 7 and 8 contained within the trunk 6. More specifically, the body of the trunk 6 is joined to these flexible arms 7 and 8 at a second end 5d by a connecting portion 14. These two arms 7 and 8 extend linearly within the opening 9, parallel to the axis of symmetry A, toward the portion 16 of the wall 13 opposite the fixed portion 15. It should be noted that each of these arms 7 and 8 may have a thickness similar to, or substantially similar to, the thickness of the flexible portion 3 of the resonators 2a and 2b.

[0041] These two arms 7 and 8 have similar axial cross-sections S3. Each axial cross-section S3 is defined with respect to the axis of symmetry B of each arm 7 and 8, which is parallel to the axis of symmetry A of the main body 6. In this configuration, the axial cross-sections S1, S2, and S4 of the main body 6 are larger than the axial cross-sections S3 of each arm 7 and 8.

[0042] Referring to Figures 6 and 2A to 2B, in this step 21, these arms 7 and 8 are designed as follows: -They are at a first distance D1 from each other. This distance D1 is preferably greater than, substantially greater than, or substantially the same as, the distance during rotation of the resonators 2b, 2c when the resonators 2b, 2c are springs or hairsprings, and - To prevent the oscillation of arms 7 and 8 from colliding with the fixed portion 15 of the wall 13 of the opening 9, there is a second distance D2 between the free ends 5b and 5c of arms 7 and 8 and the portion 16 of the wall 13 of the opening 9 opposite to the fixed portion 15.

[0043] In this configuration, the first distance D1 is greater than the second distance D2.

[0044] It should be noted that these arms 7 and 8 are designed with a thickness Er, which is preferably similar to, or substantially similar to, the thickness E2 and E3 of the flexible portions 3 of each resonator 2b and 2c formed within the plate 1. In other words, if the flexible portion 3 is the blade of the hairspring, the thickness Er of each arm 7 and 8 is similar to, or substantially similar to, the thickness E2 and E3 of the flexible portion 3. For example, these arms 7 and 8 may have a thickness Er that falls between 10 and 60 μm, preferably 30 μm.

[0045] In step 21, these arms 7, 8 are extended to a length L that can be adjusted according to a desired resonance measurement tolerance. This tolerance is defined based on at least one change in the dimensions E2, E3, H2, H3 of the flexible portion 3 of the resonators 2b, 2c associated with the vibrating members 10a, 10b, 10c. This tolerance is equal to a desired frequency interval that allows measurement of the dimensional changes E2, E3, H2, H3 on the resonators 2b, 2c, and the difference in stiffness of these resonators no longer requires correction. In this case, this value defines a measurement interval at which minute / highly sensitive dimensional changes to the flexible portion 3 of the resonators 2b, 2c are no longer necessarily determined. In other words, adjustments below this tolerance are unnecessary. This value is specifically adapted to the dimensions of this flexible portion 3 of the resonators 2b, 2c to improve the measurement of the carving thickness and the sensitivity of the changes. For example, the length L is calculated so that the change in the vibrating member at 10 Hz allows for the measurement of the change in the 10 nm dimensions E2 and E3 of the resonator.

[0046] In this step, the calculation of the lengths L of the vibrating members 10a, 10b, and 10c is performed as follows: - Specifying dimension Er, which preferably is the same as, or substantially the same as, the thickness E2, E3 of the flexible portion 3 of each resonator 2b, 2c formed within plate 1. - To define the amount of frequency change that can be measured by the measurement system, and to enable accurate frequency measurement between 2 and 10 times the standard deviation of the measurement, - Specify the minimum dimensional changes in E2, E3, H2, and H3 of the resonators 2b and 2c to be measured, - Calculate the lengths L of arms 7 and 8 that fall between 1 mm and 2 mm, so that the measurement of the frequency change can lead to conclusions about the dimensional changes of E2, E3, H2, and H3 of resonators 2b and 2c. Includes.

[0047] It should be noted that the shorter the length L of arms 7 and 8, the higher the measured resonant frequency, and the ratio between the addition or removal of a uniform thickness of material on the vibrating members 10a, 10b, and 10c and their resonant frequency is more sensitive.

[0048] In step 21, it should be noted that the vibrating members 10a, 10b, and 10c are preferably positioned within the plate 1, especially when the plate 1 is made from silicon, such that the arms 7 and 8 of the vibrating members 10a, 10b, and 10c are positioned to have the maximum or minimum Young's modulus. In fact, since silicon is anisotropic, this configuration makes it possible to avoid significant variations in Young's modulus depending on the angle used to determine structural characteristics such as stiffness. Furthermore, the maximum Young's modulus should be preferred in order to increase the accuracy of the correlation between stiffness and measurement frequency.

[0049] In the modified forms shown in Figures 2B and 2C, step 21 for forming the vibrating members 10a, 10b, and 10c is defined as follows: Each arm 7, 8 is designed with free ends 5b, 5c made from the same material as the end members 11, 12, and the end members 11, 12 have a mass greater than the remaining mass of the body of the arms 7, 8. In Figure 2B, the end member 11 has a polygonal cross-section, and in Figure 2C, this cross-section of the end member 12 is circular. These end members 11, 12 allow for a reduction in the resonant frequency of the arms 12, 8 while maintaining good sensitivity between the engraving thickness Er and this frequency. In this case, the step for calculating the lengths of the vibrating members 10a, 10b, and 10c is: - Specifying dimension Er, which preferably is the same as, or substantially the same as, the thickness E2, E3, H2, H3 of the flexible portion 3 of each resonator 2b, 2c formed within plate 1. - The system defines the amount of frequency change that can be measured, enabling accurate frequency measurement between 2 and 10 times the standard deviation of the measurement, where this frequency change can be, for example, 10 Hz. - Specify the minimum change in dimensions E2, E3, H2, and H3 of the resonators 2b and 2c to be measured. This change can be, for example, 10 nm for a measurable frequency of 10 Hz. - Calculate the lengths L of arms 7 and 8 that fall between 1 mm and 2 mm in order to draw conclusions about the changes in dimensions of E2, E3, H2, and H3 of resonators 2b and 2c by measuring the change in frequency, - To reduce the measurement frequency to a reasonable range for the measurement system, calculate the dimensions of the arm end and Includes.

[0050] Advantageously, these end members 11 and 12 provide a larger surface area than the arms 7 and 8, making it easier to measure the resonant frequencies of these vibrating members 10b and 10c.

[0051] It should be understood that the vibrating members 10a, 10b, and 10c designed during this forming step 21 have the overall shape of a tuning fork, or are tuning forks.

[0052] These vibrating members 10a, 10b, and 10c enable optimal isolation of the resonant frequency from the influence of the setting. In fact, during harmonic excitation, the setting significantly affects the resonant frequency. In the case of these vibrating members 10a, 10b, and 10c, there is a significant separation between the setting and the resonant frequencies of arms 7 and 8. The correlation between the resonant frequency and structural characteristics such as rigidity becomes independent of the quality of the setting's sculpting.

[0053] Furthermore, such vibrating members 10a, 10b, and 10c are configured such that their structural characteristics can be easily determined from a module that determines the structural characteristics within the resonator modification device. It should be noted that such vibrating members 10a, 10b, and 10c are configured to vibrate at a stable frequency, regardless of changes in certain parameters particularly related to the setup and measurement process. This stable frequency varies according to one or more parameters / structural characteristics of these vibrating members 10a, 10b, and 10c. In this embodiment, the structural characteristic of the vibrating members 10a, 10b, and 10c that significantly varies the resonant frequency is preferably the thickness Er of the arm. Other characteristics other than the thickness Er of the arm, such as stiffness and the height h of the arm, may be used. In the actual process, the frequency is measured under the engraving mask, and the dimension is derived from the frequency (thickness of the arm = value of the arm on the DRIE mask - dimension under the engraving). The stiffness of the tuning fork is not directly obtained. Next, after estimating this thickness (dimension under the engraving mask), the stiffness of the hairspring is calculated so that the necessary adjustments can be made.

[0054] Next, the method includes a step 22 in which the structural characteristics of at least one vibrating member 10a, 10b, 10c associated with at least one resonator 2b, 2c formed within plate 1 are determined. This step 22 includes a substep 23 in which the frequency of at least one resonator of the at least one vibrating member 10a, 10b, 10c is estimated. In this substep 23, the at least one vibrating member 10a, 10b, 10c is set in a state of mechanical oscillating motion around its stable equilibrium position. Then, during this motion, the resonant frequency of the vibrating member 10a, 10b, 10c is determined in a measurement step 24.

[0055] This measurement step 24 is embodied by a measurement submodule of a module that determines the structural characteristics within the resonator 2b, 2c modification device. In a modified form in which the vibrating members 10b, 10c are equipped with arms 7, 8, and each arm 7, 8 has end members 11, 12, the measurement submodule includes a speedometer that can focus on these end members 11, 12 of these arms 7, 8 that perform the oscillating motion. In this configuration, the measurement can be taken out of the plane, with the speedometer axis perpendicular to the wafer plane.

[0056] When several vibrating members 10a, 10b, and 10c are associated with single resonators 2a and 2c, it should be noted that the resonant frequencies of all these vibrating members 10a, 10b, and 10c are measured, and then the average of these frequencies is calculated and corresponds to the resonant frequency associated with this combination of vibrating members 10a, 10b, and 10c. Alternatively, the measured resonant frequency of this combination may be the resonant frequency of a single vibrating member of vibrating members 10a, 10b, and 10c, or the resonant frequency of a sample of vibrating members 10a, 10b, and 10c.

[0057] After estimating the resonant frequency, step 22 includes a substep 25 that defines the structural characteristics, such as the stiffness, of at least one vibrating member 10a, 10b, or 10c. In this substep 25, the processing unit executes an algorithm that calculates these structural characteristics from the estimated resonant frequency of at least one vibrating member 10a, 10b, or 10c.

[0058] Next, the method includes a step 26 in which a dimensional correction to be applied to each resonator 2b, 2c in the set of mechanical resonators is calculated based on the structural characteristics determined in the associated system 3. Next, in this step 26, the quantification of the dimensional correction to be applied to the resonators 2b, 2c is determined.

[0059] To make this decision, step 26 includes a substep 27 to determine, based on the determined structural characteristics, the thickness e of material to be added to or removed from at least one dimension of the resonators 2b, 2c for the set of mechanical resonators formed in forming step 20, in order to obtain a set of mechanical resonators 2a having structural characteristics such that the average value falls within a predetermined range.

[0060] This dimensional correction effectively corresponds to the thickness e of the material to be removed from or added to the resonators 2b and 2c, and to at least one of the dimensions E2, H2, E3, and H3, namely: - Only the heights H2 and H3 of the flexible part 3, or -Only the thickness E2, E3 of the flexible part 3, or - Both heights H2, H3 and thicknesses E2, E3 Make it change

[0061] This dimensional correction can be applied to one or more individual lengths of the flexible portions 3 of the resonators 2b, 2c, or over the entire length of the flexible portions 3.

[0062] Therefore, such a substep 27 can participate in shaping the resonators 2b, 2c by determining dimensional corrections, thereby giving the structural features values ​​that fall within a predetermined range.

[0063] Next, the method includes step 28 of correcting the dimensions E2, E3, H2, and H3 of mechanical resonators 2b and 2c based on calculated dimensional corrections in order to obtain a set of mechanical resonators 2a having structural characteristics in which the average value falls within a predetermined range.

[0064] In this case, if the dimensions E2, H2 of the resonator 2b are greater than the dimensions E1, H1 required to obtain a set of mechanical resonators 2a having structural characteristics such that their average values ​​fall within a predetermined range, step 28 includes a substep 29 to remove material according to the calculated thickness e of the material to be removed. This removal can then be carried out using a step of oxidizing and then deoxidizing these resonators 2b, a step that is well known in the prior art. Such a substep 29 aims to reduce the dimensions of the cross section 4b of the flexible portion 3 of the resonator 2b over a given length of the flexible portion 3 or over its entire length.

[0065] If the dimensions E3, H3 of the resonator 2c are smaller than the dimensions E1, H1 required to obtain a set of mechanical resonators 2a having structural features whose average values ​​fall within a predetermined range, step 28 includes a substep 30 to add material according to the calculated thickness e of the material to be added. This material can then be added using methods known in the prior art, such as thermal oxidation, galvanic growth, physical vapor deposition, chemical vapor deposition, atomic layer deposition, or any other addition method. Such a substep 30 aims to increase the dimensions E3, H3 of the cross section 4c of the flexible portion 3 of the resonator 2c over a given length of the flexible portion 3 or over its entire length.

[0066] Therefore, such a method makes it possible to correct dimensional errors in resonators manufactured using such methods involving photolithography and / or DRIE technology with the high precision provided by the reference stiffness indication system. [Explanation of Symbols]

[0067] 1. A plate having at least one resonator. 2a Manufactured mechanical resonator 2b Mechanical resonator formed on a plate having a cross-sectional area larger than the cross-sectional dimensions of the manufactured resonator. 2c A resonator formed on a plate having a cross-sectional area smaller than the cross-sectional dimensions of the manufactured resonator. 3. Flexible part of a mechanical resonator 4a Cross-section of the manufactured resonator 4b Cross-section of a resonator formed with dimensions larger than the dimensions of the cross-section of the manufactured resonator. 4c Cross-section of a resonator formed with dimensions smaller than the dimensions of the manufactured resonator cross-section. 5a Mounting end of the vibrating member 5b Free end of the vibrating member 5c Free end of vibrating member 6. Arbor / Trunk of Vibration Member 7. First flexible arm on the vibrating member 8. Second flexible arm on the vibrating member 9. Opening in which the vibrating member is placed 10 Vibrating member 11 End members with polygonal cross-sections 12 End members with a circular cross-section 13. Peripheral wall of the opening 14. The part that connects the arm to the trunk of the vibrating member. 15 Fixing part of the wall of the opening of the vibrating member 16 The portion of the wall opposite to the fixed part

Claims

1. A method for manufacturing a set of mechanical resonators (2a) having structural characteristics such that the average value falls within a predetermined range, wherein the structural characteristics are common to each resonator (2a) in the set, and the method is a) Step (20) of forming mechanical resonators (2b, 2c) within a plate (1), wherein the mechanical resonators (2b, 2c) have dimensions different from those required to obtain a set of mechanical resonators (2a) having structural features that fall within the predetermined range, b) step (21) in which at least one vibrating member (10a, 10b, 10c) is formed in an opening (9) made in the plate (1), wherein the member (10a, 10b, 10c) is a trunk (6) having a body which is joined at a first end (5a) to a fixing part (15) of the wall (13) inside the opening (9), and two flexible arms which are joined at a second end (5d) of the trunk (6) by a connecting part (14) The step (21) is composed of 7, 8), the arms (7, 8) are parallel to the axis of symmetry (A) of the trunk (6), and extend toward the portion (16) of the wall (13) opposite to the fixing portion (15), and the main body of the trunk (6) has a portion between the first end (5a) and the second end (5d) having an axial cross-section (S4) smaller than the axial cross-sections (S2, S1) of the first end (5a) and the second end (5d), respectively, c) A step (22) to determine values ​​for the structural characteristics of the formed at least one vibrating member (10a, 10b, 10c), d) A step (26) to calculate the dimensional correction to be applied to the formed resonators (2b, 2c) based on the values ​​determined with respect to the structural characteristics, e) A step (28) of correcting the dimensions of the formed resonators (2b, 2c) based on the dimensional correction calculated to obtain a set of resonators (2a) having structural characteristic values ​​that fall within the predetermined range of values. Methods that include...

2. The method according to claim 1, wherein the forming step (21) specifies that the axial cross-section (S4) is larger than the respective axial cross-sections (S3) of the arms (7, 8).

3. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) specifies that each of the arms (7, 8) is designed to be of length (L), the length (L) may be adjusted according to a resonance measurement tolerance factor, the resonance measurement tolerance factor is defined by at least one dimension (E2, E3, H2, H3) of the flexible portion (3) of the resonator (2b, 2c) associated with the at least one vibrating member (10a, 10b, 10c).

4. The step (21) of forming the vibrating members (10a, 10b, 10c) is such that one arm (7) moves to a first distance (D １ The method according to claim 1, wherein the free ends (5b, 5c) of the arms (7, 8) are designed to be spaced apart from the other arm (8) by a second distance (D2) from the opposite portion (16) of the fixed portion (15), and the first distance (D1) is greater than the second distance (D2).

5. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) is specified to be designed such that each of the arms (7, 8) is the same as, or substantially the same as, the thickness (Er) of the flexible portion (3) of each resonator (2b, 2c) formed in the plate (1).

6. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) is characterized in that each of the arms (7, 8) is designed with free ends (5b, 5c) made from the same material as the end members (11, 12), and the end members (11, 12) have a mass greater than the remaining mass of the body of the arms (7, 8).

7. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) is characterized in that each of the arms (7, 8) is designed with free ends (5b, 5c) made from the same material as the end members (11, 12), the end members (11, 12) have a mass greater than the remaining mass of the body of the arms (7, 8), and the end members (11, 12) have a circular or polygonal cross-section.

8. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) is specified to be such that the body of the trunk (6) is designed to have a cross section (S4) between one-half and one-fifth of the axial cross sections (S2, S1) of the first end (5a) and the second end (5d), respectively.

9. The method according to claim 1, wherein the steps (20, 21) of forming the mechanical resonators (2b, 2c) and the at least one vibrating member (10a, 10b, 10c) are carried out by engraving, in particular by deep reactive ion etching.

10. The method according to claim 1, wherein the step (21) of forming each of the vibrating members (10a, 10b, 10c) is performed within the plate (1) for at least one resonator (2b, 2c) in the set of mechanical resonators (2b, 2c).

11. The method according to claim 1, wherein the forming step (21) is to generate a plurality of vibrating members (10a, 10b, 10c) surrounding at least one resonator (2b, 2c) in the plate (1).

12. The method according to claim 1, wherein the determining step (22) includes a substep (23) of estimating at least one resonant frequency for each vibrating member (10a, 10b, 10c) associated with at least one resonator (2b, 2c) in the set of resonators (2b, 2c).

13. The method according to claim 12, wherein the determining step (22) includes a substep (25) of defining structural features for each of the vibrating members (10a, 10b, 10c) that are the same as structural features common to each of the formed resonators (2b, 2c), the substep (25) is performed by a processing unit, the processing unit is connected to a device for modifying the formed resonators (2b, 2c), and executes an algorithm for calculating the structural features of each of the vibrating members (10a, 10b, 10c) based on the estimated resonant frequencies.

14. The method according to any one of claims 1 to 13, wherein the calculation step (26) includes a substep (27) of determining the thickness (e) of material to be added to or removed from at least one dimension of each of the resonators (2b, 2c) associated with the vibrating members (10a, 10b, 10c), based on values ​​determined for the structural characteristics of each of the vibrating members (10a, 10b, 10c).

15. The method according to claim 1, wherein the vibrating member (10) is in the shape of a sound tuner.

16. The method according to claim 1, wherein the aforementioned structural feature is a rigidity characteristic.

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