Method for manufacturing mechanical resonators

Abstract

To provide a method for manufacturing a mechanical resonator. [Solution] One aspect of the present invention relates to a method for manufacturing a set of mechanical resonators (2a) having structural characteristics having an average value that falls within a predetermined range of values, the method comprising: forming mechanical resonators (2b, 2c) and vibrating members (10a, 10b, 10c) on a plate (1) (21); calculating dimensional corrections to be applied to the formed resonators (2b, 2c) based on values ​​determined for structural characteristics (26); and then correcting the dimensions of the formed resonators (2b, 2c) based on the dimensional corrections calculated to obtain a set of resonators (2a) having structural characteristic values ​​that fall within a predetermined range of values ​​(28).

Description

Technical Field

[0001] The present invention relates to the field of manufacturing mechanical resonators, particularly in the field of timepieces. More specifically, the present invention relates to a method for manufacturing a set of mechanical resonators, in which common structural features such as rigidity are included within a predetermined range of values for these resonators. Regarding the method for.

Background Art

[0002] In the prior art, it is common to use a method for manufacturing mechanical resonators such as 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 when such a method is used, geometric dissipation occurs between hairsprings that are conventionally formed in the same pattern on the same plate.

[0004] To improve these drawbacks, solutions have been proposed in the prior art, particularly in European Patent Nos. 3181938 and 3181939. These prior arts 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 rigidity; b) determining the rigidity of the hairspring formed in step a) by measuring the vibration frequency of the hairspring combined with a template having a predetermined inertia; c) calculating the thickness of the material to be removed to obtain a hairspring having a predetermined rigidity; and d) removing the calculated thickness of the material from the hairspring formed in step a). In order to further improve dimensional quality, steps b), c), and d) can be repeated.

[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 predetermined rigidity; b) determining the rigidity of the hairspring formed in step a) by measuring the oscillation frequency of the hairspring coupled to a balance wheel having predetermined inertia; c) calculating the thickness of missing material to obtain a hairspring with predetermined rigidity; and d) modifying the hairspring formed in step a) to compensate for the thickness of missing material, wherein steps b), c), and d) can be repeated to further improve dimensional quality.

[0007] Such methods can be improved, particularly to limit plate contamination that may occur during the measurement step.

[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 project] [Problems that the invention aims to solve]

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

[0011] The present invention also aims to improve the precision in the manufacture of a set of mechanical resonators having structural characteristics such as rigidity with an average value 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 features having an average value that falls within a predetermined range, wherein the structural features are common to each resonator in the set, and the method is as follows: a) A step of forming a mechanical resonator on a plate having dimensions different from those required to obtain a set of mechanical resonators having structural characteristics that fall within a predetermined range of values, b) A step of forming at least one vibrating member in an opening formed in a 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 fixed portion, and the second end having an axial cross-section smaller than the axial cross-section of the first end and larger than the axial cross-section of each of the flexible arms, c) A step of determining a value for the structural characteristics of at least one vibrating member that has been formed, d) A step of calculating dimensional corrections to be applied to the formed resonator based on the values ​​determined for 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; This includes methods.

[0013] In other embodiments, The step of forming the vibrating members provides each arm designed to have a length that can be adjusted according to a resonance measurement tolerance coefficient defined from at least one dimension of the flexible portion of the resonator associated with at least one vibrating member. The step of forming the vibrating member provides each arm designed to have a first and a second distance from the fixing portion of the trunk body and the wall of the opening, respectively, wherein the first distance is greater than the second distance. The step of forming the vibrating members provides each arm designed to have a thickness similar to or substantially similar to the thickness of the flexible portion of each resonator formed in the plate. The step of forming the vibrating member is to provide each arm, which is designed to have a free end made of the same material as an end member having a mass greater than the mass of 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 provides a trunk body designed to have a cross-section at a second end that is 3 to 5 times smaller than the cross-section at a first end. 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 carried out on a plate with respect to at least one resonator of the set of mechanical resonators. The forming step involves forming multiple vibrating members on a plate that surround at least one resonator. The determination step includes a substep in which at least one resonant frequency is estimated for each vibrating member associated with at least one resonator in the set of resonators. The determination step includes a substep in which structural features of the same nature as common structural features of each formed resonator are defined for each vibrating member, the substep being performed by a processing unit connected to a device for modifying the formed resonators, which executes an algorithm to calculate this structural feature of each vibrating member based on the estimated resonant frequency. The calculation step includes a substep in which the thickness of material to be added to or removed from at least one dimension of each resonator associated with the vibrating member is determined based on values ​​determined for the structural characteristics of each vibrating member. The vibrating element is shaped like a tuning fork. The structural characteristic is its rigidity.

[0014] Other features and advantages of the present invention will become more clearly apparent from the following description of specific embodiments of the present invention, which are provided by way of illustration and non-limitation only, and from the accompanying drawings.

Brief Description of the Drawings

[0015] [Figure 1] It is a schematic diagram of a plate, which includes a set of mechanical resonators formed simultaneously within this plate, according to an embodiment of the present invention, particularly by engraving. [Figure 2A] It is an enlarged view of a vibrating member in the form of a tuning fork, which enables determination of characteristic values common to the mechanical resonators, and this vibrating member having these resonators is included in the plate shown in FIG. 1 according to an embodiment of the present invention. [Figure 2B] It is a modification of the vibrating member of FIG. 2A according to an embodiment of the present invention, and the free end of the arm of this member is provided with an end member having a mass larger than the mass of the remaining part of the body of this arm. [Figure 2C] It is a modification of the vibrating member of FIG. 2A according to an embodiment of the present invention, and the free end of the arm of this member is provided with an end member having a mass larger than the mass of the remaining part of the body of this arm. [Figure 3] It is a schematic cross-sectional view of the flexible part of a resonator manufactured using this method according to an embodiment of the present invention, and the cross-section has dimensions necessary to obtain a set of mechanical resonators having structural features with an average value included within a predetermined value range. [Figure 4] It is a schematic cross-sectional view of the flexible part of a resonator formed on a plate using this method according to an embodiment of the present invention, and the cross-section has dimensions larger than the dimensions of the cross-section of the manufactured resonator shown in FIG. 3. [Figure 5] It is a schematic cross-sectional view of the flexible part of a resonator formed on a plate using this method according to an embodiment of the present invention, and the cross-section has dimensions smaller than the dimensions of the cross-section of the manufactured resonator shown in FIG. 3. [Figure 6]This is a flowchart illustrating a method for manufacturing a set of mechanical resonators having structural characteristics with an average value that falls within a predetermined range, according to an embodiment of the present invention. [Modes for carrying out the invention]

[0016] Figure 6 shows a schematic diagram of a method for manufacturing a set of mechanical resonators 2a on a material plate 1 (called a "wafer"). This plate 1 may be a single-crystal silicon plate, but a plate made of other materials can also be used, such as polycrystalline or amorphous silicon, other semiconductor materials, glass, ceramics, carbon, quartz, metals or alloys, or composite materials containing these materials. However, single-crystal silicon is relatively unresponsive to magnetic fields and belongs to the cubic crystal class with 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 rigid connecting part 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 a watch, particularly a mechanical adjuster for adjusting a mechanical watch movement. In a watch, the oscillation of such a resonator determines the speed of the movement. Many watches have adjusters that, for example, include a hairspring as a resonator mounted on the balance wheel axis and set to oscillate by the escapement. The natural frequency of the spring-loaded balance wheel adjusts the watch. Such a watch hairspring comprises an elastically flexible strand, one end of which is connected to a collet, and wound helically to form several consecutive windings, the last winding of which is extended by a mounting segment designed to be attached to a fixed balance bar, for example by a hairspring stud. Such a collet is designed to be fixed to a pivot arbor. Other known types of resonators are based, for example, on an oscillating bar or other mechanical components.

[0018] Therefore, this method makes it possible to manufacture a set of resonators 2a having structural features with average values ​​that fall within a predetermined range. In this method, this feature is common to all resonators 2a in this set. In other words, these resonators have the same structural feature. This structural feature may be a stiffness feature of the resonator 2a, particularly its flexible portion 3. In this case, this method makes it possible to select the resonators 2a of this particular set from among a plurality of resonators formed on the plate 1. To this end, this method helps to create a map showing the geometric dispersion between the dimensions of the resonators formed on the plate, and consequently the dispersion between their common structural features, and corrects the selected set of resonators so that they have structural features with average values ​​that fall within a predetermined range. Such a method aims to ensure very high dimensional accuracy of the manufactured resonators 2a and, incidentally, to guarantee more precise structural features 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 features may be the stiffness of the spring, particularly its blades. In this case, the method can be a method for manufacturing a set or assembly of watch hairsprings 2a within a plate 1, having an average stiffness that falls within a predetermined range.

[0020] Referring to Figure 1, a set of mechanical resonators 2b and 2c is formed on a plate 1 of material. In this set, each resonator 2b and 2c has a flexible portion 3 which includes a rigid connection for fixing the resonator to an axis or arbor.

[0021] In the context that these resonators 2b and 2c are hairsprings, the hairsprings are equipped with collets for fixing them 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 limited to, 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 on the plate 1, and an apparatus for modifying the resonators 2b, 2c formed on the plate 1.

[0023] The apparatus for forming the resonators 2b, 2c and the vibrating members 10a, 10b, 10c can be used to perform microfabrication techniques such as photolithography, machining, and engraving on 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 the structural characteristics of resonators 2b and 2c, and a module for dimensional correction of resonators 2b and 2c. This module for determining structural characteristics is, A submodule for driving / releasing the mechanical vibration motion of the vibrating members 10a, 10b, and 10c around their stable equilibrium positions in the main body, It includes a submodule for measuring the resonant frequencies of vibrating members 10a, 10b, and 10c in mechanical vibration motion.

[0025] With respect to the dimensional correction module for resonators 2b and 2c, this module comprises a submodule for calculating the corrections to be made to resonators 2b and 2c, and a submodule for correcting these resonators 2b and 2c, using oxidation and subsequent deoxygenation techniques, thermal oxidation, galvanic growth, physical vapor deposition, chemical vapor deposition, atomic layer deposition, or any other additional process.

[0026] In this system, the processing unit is connected to the devices for forming resonators 2b, 2c and at least one vibrating member 10a, 10b, 10c on plate 1, and for modifying the formed resonators 2b, 2c. Such a processing unit comprises at least a processor and a memory element. The unit can execute instructions for implementing a computer program intended to guide / control these two devices, for example. In particular, such a unit can ensure the induction / control of the drive and measurement submodules, as well as computation / 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 can use a predictive or simulation model to determine the structural characteristics of at least one vibrating member 10a, 10b, 10c, particularly its stiffness, and the dimensional corrections made to the resonators 2b, 2c formed on plate 1.

[0027] Such a method includes step 20, in which mechanical resonators 2b, 2c are formed on plate 1 according to dimensions E2, E3, H2, H3 which are different from the dimensions E1, H1 required to obtain a set of mechanical resonators 2a having structural features with average values ​​that fall within a predetermined range.

[0028] In step 20, the resonators 2b and 2c are formed on plate 1. It is preferable that these resonators 2b and 2c are formed simultaneously within plate 1. The formation of these resonators 2b and 2c within 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 on the plate 1 have a flexible section 3 having cross-sections 4b, 4c with dimensions E2, H2, E3, H3. The cross-sections 4b, 4c of this flexible section 3 preferably have a polygonal shape similar to that of a hairspring blade and are characterized by the 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 with average values ​​that fall within a predetermined range. In other words, the flexible section 3 of each resonator 2b, 2c may have cross-sections 4b, 4c with dimensions E2, H2, E3, H3 that are larger or smaller than the dimensions E1, H1 required for the cross-section 4a of this flexible section of a manufactured resonator 2a, enabling the acquisition of structural features with average values ​​that fall within a predetermined range.

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

[0031] During this formation step 20, the mechanical resonators 2b and 2c that are formed are To obtain a set of mechanical resonators 2a having structural characteristics such as stiffness with average values ​​that fall within a predetermined range, dimensions E2 and H2 are larger than the dimensions E1 and H1 required, i.e., the height H2 and / or thickness E2 of the flexible part 3 are larger than the height H1 and / or thickness E1 of the flexible part 3 of the mechanical resonator 2a having structural characteristics such as stiffness with average values ​​that fall within a predetermined range, To obtain a set of mechanical resonators 2a having structural characteristics such as stiffness with average values ​​that fall within a predetermined range, dimensions E3 and H3 are smaller than the dimensions E1 and H1 required, that is, the height H3 and / or thickness E3 of the flexible part 3 of the flexible part 3 of the mechanical resonator 2a having structural characteristics such as stiffness with average values ​​that fall within a predetermined range, Please note that it may be possible to have this.

[0032] The method also includes step 21 in which at least one vibrating member 10a, 10b, 10c is formed on 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 carried out on the same plate 1 that includes the formed mechanical resonators 2b and 2c, preferably simultaneously with step 20 in which these resonators 2b and 2c are formed.

[0034] In step 21, at least one vibrating member 10a, 10b, 10c is generated on plate 1 for at least one resonator 2b, 2c of the set of mechanical resonators 2b, 2c. For example, vibrating members 10a, 10b, 10c can be generated for several resonators 2b, 2c placed in close proximity to each other, or for each resonator 2b, 2c. Alternatively, several vibrating members 10a, 10b, 10c can be placed around a single resonator 2b, 2c within plate 1, particularly in close proximity to this resonator 2b, 2c.

[0035] In step 21, the members 10a, 10b, and 10c are designed within an opening 9 provided in the plate 1. Such an opening 9 is a through-hole formed in the thickness direction of the plate 1 and is provided with 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 vibration motion.

[0036] As described above, the vibrating members 10a, 10b, and 10c preferably consist of a trunk / arbor 6 having a linear body, which is joined at one end 5a, also called the mounting end 5a, to the peripheral wall 13 of the opening 9, and in particular to the fixed portion 15 of the wall 13. The trunk body 6 also includes a second end 5d having an axial cross-section S1 smaller than the axial cross-section S2 of the first end 5a. The trunk body has an axial cross-section S4 that is essentially constant between its first end 5a and the second end 5d. It should be noted that the cross-section S1 of the second end 5d is preferably 3 to 5 times smaller than the cross-section S2 of the first end 5a. This difference in cross-section can reduce the stiffness of the trunk 6 at this second end 5d, and when measuring the structural characteristics of the vibrating members 10a, 10b, and 10c, it can create a difference between the in-phase mode and the out-of-phase mode of the arms 7 and 8, which is used in step 22 to determine the relative values ​​of these structural characteristics, as described below. Note that the in-phase mode corresponds to the mode in which the arms vibrate simultaneously in the same direction. In the out-of-phase mode, the arms vibrate with a 180-degree phase shift. Both arms move in and out simultaneously.

[0037] Furthermore, it should be noted that the difference in cross-section increases the rigidity of the trunk body 6 at the first end 5a in order to isolate the vibrational motion of the arms 7 and 8 of plate 1 when this measurement is performed.

[0038] 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 its 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 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.

[0039] 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 trunk body 6. In this configuration, the first and second axial cross-sections S1 and S2 of the trunk body 6 are larger than the axial cross-sections S3 of each arm 7 and 8.

[0040] Referring to Figures 6 and 2A to 2B, in this step 21, these arms 7 and 8 are A first distance D1 from the main body of the trunk 6 of the vibrating members 10a, 10b, 10b, preferably a first distance D1 that is greater than, substantially greater than, or substantially the same as, the winding distance of the resonators 2b, 2c when the resonators 2b, 2c are springs or hairsprings, The second distance D2 from the fixing part 15 of the wall 13 of the opening 9, It is designed in [location / location].

[0041] In this configuration, the first distance D1 is greater than the second distance D2.

[0042] It should be noted that these arms 7 and 8 are designed to have a thickness Er that is preferably similar to or substantially similar to the thicknesses E2 and E3 of the flexible portions 3 of each resonator 2b and 2c formed in the plate 1. In other words, if the flexible portion 3 is a hairspring blade, the thickness Er of each arm 7 and 8 is similar to or substantially similar to the thicknesses E2 and E3 of the flexible portion 3. For example, these arms 7 and 8 can have a thickness Er of 10 to 60 μm, preferably 30 μm.

[0043] In step 21, these arms 7, 8 are drawn to a length L that can be adjusted according to a desired resonance measurement tolerance. This tolerance is defined based on at least one variation of the dimensions E2, E3, H2, H3 of the flexible portion 3 of the resonators 2b, 2c associated with these vibrating members 10a, 10b, 10c. This tolerance has a value equal to a desired frequency interval that allows the dimensional variation E2, E3, H2, H3 to be measured on the resonators 2b, 2c, resulting in a difference in the stiffness of this resonator that no longer requires correction. This value thus specifies a measurement interval below which minute / sensitive dimensional variations of the formed flexible portion 3 of the resonators 2b, 2c are no longer necessarily detectable. In other words, no adjustment is required below this tolerance. This value is specifically adapted to the dimensions of this flexible portion 3 of the resonators 2b, 2c to improve the sensitivity of the measurement and the sensitivity of changes in the thickness of the engraving. For example, the length is calculated such that a 10 Hz fluctuation in the vibrating member allows for the measurement of a 10 nm dimensional fluctuation E2, E3 in the resonator.

[0044] In this step, the process for calculating the lengths of the vibrating members 10a, 10b, and 10c is as follows: The dimensions Er are defined to be preferably the same as or substantially the same as the thicknesses E2, E3, H2, H3 of the flexible portions 3 of each resonator 2b, 2c formed on plate 1, To define the frequency variation that can be measured by the measurement system, which enables accurate measurement of frequency within 2 to 10 times the standard deviation of the measurement, To specify the minimum dimensional variations of E2, E3, H2, and H3 of the resonators 2b and 2c to be measured, This includes calculating the lengths L of arms 7 and 8 that fall between 1 mm and 2 mm, so that conclusions can be drawn regarding the dimensional variations of E2, E3, H2, and H3 of resonators 2b and 2c by measuring frequency fluctuations.

[0045] It should be noted that the shorter the length L of arms 7 and 8, the higher the measured resonant frequency becomes, and the ratio between the addition or removal of uniform thickness material on the vibrating members 10a, 10b, and 10c and their resonant frequency becomes more sensitive.

[0046] In step 21, it should be noted that the vibrating members 10a, 10b, and 10c are preferably positioned within the plate 1 such that their arms 7 and 8 are positioned so that their Young's modulus is maximized or minimized, especially if the plate 1 is made of silicon. In fact, since silicon is anisotropic, this configuration allows for avoidance of 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 to improve the accuracy of the correlation between stiffness and the measured frequency.

[0047] In the modified examples shown in Figures 2B and 2C, step 21, in which the vibrating members 10a, 10b, and 10c are formed, specifies that each arm 7, 8 is designed to have free ends 5b, 5c made of a material having an end member 11 having a mass greater than the mass of the rest of the body of the arm 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 7, 8, while maintaining good sensitivity between the engraving thickness Er and this frequency. In this case, the process for calculating the lengths of the vibrating members 10a, 10b, and 10c is as follows: The dimensions Er are defined to be preferably the same as or substantially the same as the thicknesses E2, E3, H2, H3 of the flexible portions 3 of each resonator 2b, 2c formed on plate 1, To define a frequency variation that can be measured by a measurement system, which enables accurate measurement of frequency within 2 to 10 times the standard deviation of the measurement, and which can be defined as, for example, 10 Hz. To specify the minimum dimensional variation of E2, E3, H2, and H3 of the resonators 2b and 2c to be measured, where this variation can be, for example, 10 nm for a measurable frequency variation of 10 Hz. By measuring frequency variations, it becomes possible to draw conclusions regarding the dimensional variations of E2, E3, H2, and H3 of resonators 2b and 2c. This involves calculating the lengths L of arms 7 and 8 that fall within the range of 1 mm to 2 mm, and This includes calculating the dimensions of the arm ends in order to reduce the measurement frequency to a reasonable range for the measurement system.

[0048] Advantageously, these end members 11 and 12 provide a larger surface area than the surface area of ​​the arms 7 and 8, thereby facilitating the measurement of the resonant frequencies of the vibrating members 10b and 10c.

[0049] It is understood that the vibrating members 10a, 10b, and 10c designed during this forming step 21 have or are tuning forks in general shape.

[0050] These vibrating members 10a, 10b, and 10c enable optimal decoupling of the setting effect with respect to the resonant frequency. In fact, during harmonic excitation, the setting has a significant impact on the resonant frequency. In the case of these vibrating members 10a, 10b, and 10c, there is a significant decoupling between the setting and the resonant frequencies of arms 7 and 8. The correlation between the resonant frequency and structural characteristics such as stiffness becomes independent of the quality of the setting's engraving.

[0051] Furthermore, such vibrating members 10a, 10b, and 10c are configured to allow for easy determination of their structural characteristics from a module for determining the structural characteristics of a 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 those related to the setup and manufacturing process. This stable frequency varies according to one or more parameters / structural characteristics of the vibrating members 10a, 10b, and 10c. In this embodiment, the structural characteristic of the vibrating members 10a, 10b, and 10c that significantly changes the resonant frequency is preferably the arm thickness Er. In addition to the arm thickness Er, other characteristics such as stiffness and arm height h can be used. In the actual process, the frequency is measured and the dimension is derived from the frequency under the engraving mask (arm thickness = value of the arm on the DRIE mask - dimension under engraving). The stiffness of the tuning fork cannot be obtained directly. Therefore, once this thickness (dimension under the engraving mask) is estimated, the stiffness of the hairspring can be calculated, thereby allowing for necessary adjustments.

[0052] Therefore, this 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 on plate 1 are determined. This step 22 includes a substep 23 in which at least one resonant frequency 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 into mechanical vibration motion around its stable equilibrium position. During this motion, the resonant frequency of the vibrating member 10a, 10b, 10c is then determined in a measurement step 24.

[0053] This measurement step 24 is embodied by a measurement submodule for determining the structural characteristics within the resonator 2b, 2c modification devices. In a modified version of the vibrating members 10b, 10c, each having arms 7, 8 with 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 vibrating motion. In this configuration, the measurement can be performed outside the wafer surface with the axis of the speedometer perpendicular to the wafer surface.

[0054] Note that when several vibrating members 10a, 10b, and 10c are associated with a single resonator 2a, 2c, all resonant frequencies of these vibrating members 10a, 10b, and 10c are measured, and then the average of these frequencies is calculated to correspond to the resonant frequency for this combination of vibrating members 10a, 10b, and 10c. Alternatively, the measured resonant frequency for this combination may be the resonant frequency of only one of the vibrating members 10a, 10b, and 10c, or the resonant frequency of a sample of the vibrating members 10a, 10b, and 10c.

[0055] Once the resonant frequency is estimated, step 22 includes a substep 25 in which structural characteristics, such as the stiffness, of at least one vibrating member 10a, 10b, or 10c are defined. In this substep 25, the processing unit executes an algorithm to calculate these structural characteristics from the estimated resonant frequency of at least one vibrating member 10a, 10b, or 10c.

[0056] Next, this method includes a step 26 in which, based on the structural characteristics determined for the relevant system 3, dimensional corrections are applied to each resonator 2b, 2c in the set of mechanical resonators. In this step 26, the quantification of the dimensional corrections applied to the resonators 2b, 2c is determined.

[0057] To this end, step 26 includes a substep 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 resonators 2b, 2c is determined with respect to the set of mechanical resonators formed in forming step 20, and a set of mechanical resonators 2a having structural characteristics having an average value that falls within a predetermined range.

[0058] This dimensional correction applies to at least one of the dimensions E2, H2, E3, and H3 of the resonators 2b and 2c, i.e., Only the heights H2 and H3 of the flexible part 3, or Only the thicknesses E2 and E3 of the flexible part 3, or Both heights H2 and H3, and thicknesses E2 and E3. This effectively corresponds to the thickness e of the material removed from or added to the resonators 2b and 2c, thereby changing the resonator.

[0059] This dimensional correction can be performed for one or more separate lengths of the flexible portions 3 of the resonators 2b, 2c, or over the entire length of the flexible portions 3.

[0060] Therefore, such a substep 27 makes it possible to participate in shaping the resonators 2b, 2c by determining dimensional corrections, thereby giving the resonators values ​​of structural features that fall within a predetermined range of values.

[0061] Next, the method includes step 28 of modifying 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 features with average values ​​that fall within a predetermined range.

[0062] 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 features with average values ​​that fall within a predetermined range, step 28 includes a substep 29 in which material is removed according to a calculated thickness e of the material to be removed. This removal can then be carried out using the oxidation and subsequent deoxygenation process of these resonators 2b, which 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 or over its entire length.

[0063] 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 with average values ​​that fall within a predetermined range, step 28 includes a substep 30 in which material is added according to a 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 process. 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.

[0064] Therefore, such a method makes it possible to correct dimensional errors in resonators manufactured using such methods, including photolithography and / or DRIE techniques, with the high precision provided by the reference stiffness indicator system. [Explanation of Symbols]

[0065] 1. A plate having at least one resonator. 2a Manufactured mechanical resonator 2b Mechanical resonator formed on a plate having a cross-section larger than the cross-sectional dimensions of the manufactured resonator. 2c A resonator formed on a plate having a cross-section 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 formed resonator having dimensions larger than the dimensions of the cross-section of the manufactured resonator. 4c Cross-section of a formed resonator having dimensions smaller than the dimensions of the cross-section of the manufactured resonator. 5a Mounting end of the vibrating member 5b, 5c Free ends of the vibrating members 6. Arbor / Trunk of Vibration Member 7. First flexible arm on the vibrating member 8. Second flexible arm on the vibrating member 9. Opening where 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

Claims

1. A method for manufacturing a set of mechanical resonators (2a) having structural characteristics having an average value that falls within a predetermined range, wherein the structural characteristics are common to each resonator (2a) in the set, and the method is a) A step (20) of forming mechanical resonators (2b, 2c) on a plate (1) having dimensions different from the dimensions required to obtain a set (2a) of mechanical resonators having structural characteristics that fall within the range of the predetermined values, b) A step (21) of forming at least one vibrating member (10a, 10b, 10c) in an opening (9) formed in the plate (1), wherein the member (10a, 10b, 10c) consists of a trunk (6) having a body joined at a first end (5a) to a fixing portion (15) of the wall (13) inside the opening (9), and two flexible arms (7, 8) joined at a second end (5d) of the trunk (6) by a connecting portion (14), wherein the arms (7, 8) are parallel to the axis of symmetry (A) of the trunk (6), extend toward the fixing portion (15), and the second end (5d) has an axial cross-section (S1) that is smaller than the axial cross-section (S2) of the first end (5a) and larger than the axial cross-section (S3) of each of the flexible arms (7, 8), c) A step (22) to determine a value for the structural characteristics of the formed at least one vibrating member (10a, 10b, 10c), d) A step (26) to calculate a dimensional correction to be applied to the formed resonators (2b, 2c) based on the values ​​determined for 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 range of predetermined values, Methods that include...

2. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) provides each arm (7, 8) designed to have a length (L) that can be adjusted according to a resonance measurement tolerance coefficient defined from 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).

3. The step (21) of forming the vibrating members (10a, 10b, 10c) is performed with respect to the fixing portion (15) of the main body of the trunk (6) and the wall (13) of the opening (9) at a distance of first and second (D １ , D ２ The method according to claim 1, providing each arm designed to have a first distance (D1) greater than the second distance (D2).

4. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) provides each arm (7, 8) which is designed to have a thickness (Er) similar to or substantially similar to the thickness of the flexible portion (3) of each resonator (2b, 2c) formed on the plate (1).

5. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) provides each arm (7, 8) which is designed to have a free end (5b, 5c) made of the same material as an end member (11, 12) having a mass greater than the mass of the rest of the body of the arm (7, 8).

6. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) provides each arm (7, 8) which is designed to have a free end (5b, 5c) made of the same material as an end member (11, 12) having a mass greater than the mass of the rest of the body of the arm (7, 8), and the end member (11, 12) has a circular or polygonal cross-section.

7. The method according to claim 1, wherein the step (21) of forming the vibrating members (10a, 10b, 10c) provides the body of the trunk (6) which is designed to have a cross-section (S1) of the second end (5d) that is 3 to 5 times smaller than the cross-section (S2) of the first end (5a).

8. 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.

9. The method according to claim 1, wherein the step (21) of forming each vibrating member (10a, 10b, 10c) is performed on the plate (1) with respect to at least one resonator (2b, 2c) of the set of mechanical resonators (2b, 2c).

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

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

12. The method according to claim 11, wherein the determination step (22) includes a substep (25) in which structural features of the same nature as the structural features common to each formed resonator (2b, 2c) are defined for each vibrating member (10a, 10b, 10c), the substep (25) is performed by a processing unit connected to a device for modifying the formed resonators (2b, 2c) and executes an algorithm for calculating this structural feature of each vibrating member (10a, 10b, 10c) based on the estimated resonant frequencies.

13. The method according to claim 1, wherein the calculation step (26) includes a substep (27) in which the thickness (e) of material to be added to or removed from at least one dimension of each resonator (2b, 2c) associated with the vibrating members (10a, 10b, 10c) is determined based on the value determined for the structural features of each vibrating member (10a, 10b, 10c).

14. The method according to claim 1, wherein the vibrating member (10) is shaped like a tuning fork.

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

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