ZT Crystal Resonator

Abstract

To provide ZT crystal resonators. [Solution] One aspect of the present invention relates to a resonator, the resonator comprising a resonator plate having a surface having a thickness portion, a maximum length portion and a width portion, the resonator plate being a ZT cut quartz crystal, and a frame having a C-shaped portion, the C-shaped portion comprising a first arm portion and a second arm portion that at least partially extend around the lateral edge portion of the resonator plate, and each of the first arm portion and the second arm portion being connected to the resonator plate by a mooring portion.

Description

Technical Field

[0001] The present invention relates to a small crystal resonator, which is machined from a ZT-cut crystal and is configured to oscillate in a length extension contour mode along the edge of the plate.

Background Art

[0002] ZT crystal resonators are described in prior art documents such as French Patent No. 2435855, French Patent No. 2521782, French Patent No. 2634067, etc.

[0003] The cut angle of the ZT resonator is selected to achieve a vanishing first-order frequency-temperature coefficient and a slight coupling of the surface shear mode and the extension mode along the other edge of the plate. Similar characteristics characterized by various ZT cuts can be obtained by a prior rotation of the angle Ψ about the Z axis, a subsequent rotation Φ about the X' axis, and possibly a rotation of the angle θ about the Z' axis perpendicular to the plane of the plate. A common cut has Ψ = 90°, the second rotation is approximately X' = Y, Φ = 26.5° and θ = 20° about Z'. This cut is called ZTY. The probably simplest cut of the ZT family is a single rotation about X with Φ = 24°, called ZTX.

[0004] By appropriately selecting the aspect ratio of the plate, the second-order temperature coefficient also becomes zero due to the residual coupling between the (extension) modes. Thus, a third-order frequency-temperature behavior is obtained. The third-order temperature coefficient is about half of the third-order temperature coefficient of an AT-cut resonator. Further, for a given frequency, ZT can be made significantly smaller than AT.

[0005] For typical dimensions of ZT, its resonance is in the range between 1 and 20 MHz.

[0006] Since contour modes respond to impacts to the outer periphery, the manufacturing method must ensure precise shape control. Furthermore, special attention must be paid to the fixing process. The fixing process ensures good isolation from the package while keeping the resonator in place, thus maintaining the high quality coefficient and outstanding thermal characteristics of the ZT resonator.

[0007] Conventional fixation was achieved by the resonant arm, minimizing interference to the modes (Figure 1). However, the shape of the fixation part is also quite important.

[0008] Figure 1 shows an example of a conventional ZT-cut quartz crystal resonator 100, which comprises a first resonator plate 101 and a second resonator plate 102 connected together by a resonant arm 103. The resonant arm 103 is connected to an assembly 104 via a suspension arm 105. The first resonator plate 101, the second resonator plate 102, the resonant arm 103, the assembly 104, and the suspension arm 105 are all in the same plane. One surface of each resonator plate supports a first electrode (not shown), and the opposite surfaces of each resonator plate support a second electrode (not shown), and both electrodes are electrically coupled to an AC field generator (not shown). The first and second electrodes are designed and configured to generate oscillations of the two resonator plates in the width direction of the resonator plates, as indicated by the dashed arrows. The two resonator plates are balanced on both sides of the resonant arms and the assembly. The assembly is positioned between the two resonator plates to minimize the width of the resonator. Due to the presence of the two resonator plates connected by the resonant arms, the length portion 106 of the resonator is relatively long, for example, 3850 μm, while the width portion 107 of the resonator plates is also relatively long, for example, 2024 μm.

[0009] While ZT-cut quartz resonators need to be miniaturized, this miniaturization is limited by the difficulty of machining them to smaller sizes due to their complex design. Furthermore, the resonant arms and support arms must remain sufficiently wide to withstand the mechanical constraints imposed by the complex resonator plate. The symmetry of the resonant structure must be well controlled to minimize energy loss and, consequently, damping in the assembly. [Prior art documents] [Patent Documents]

[0010] [Patent Document 1] French Patent No. 2435855 [Patent Document 2] French Patent No. 2521782 [Patent Document 3] French Patent No. 2634067 [Overview of the project] [Problems that the invention aims to solve]

[0011] The present invention aims to provide an alternative design for ZT-cut quartz resonators, overcoming the difficult constraints associated with miniaturizing such resonators. [Means for solving the problem]

[0012] According to the first embodiment, the resonator is - A resonator plate having a surface with a thickness portion, a maximum length portion and a width portion, wherein the resonator plate is made of ZT cut quartz, - A frame with a C-shaped section The C-shaped portion comprises a first arm and a second arm that at least partially extend around the lateral edge of the resonator plate, and each of the first and second arms is connected to the resonator plate by a mooring portion.

[0013] The nodal plane is defined, which is perpendicular to the surface of the resonator plate, passes through the central longitudinal axis of the resonator plate, and the anchoring portion passes through the nodal plane.

[0014] Preferably, the resonator plate is configured to oscillate on both sides of the nodal surface in the width direction of the resonator plate, and the C-shaped portion of the frame is spaced apart from the resonator plate to prevent the resonator plate from coming into contact with the frame while the resonator plate is oscillating, and to ensure separation of the plate and the frame.

[0015] Preferably, the resonator plate comprises at least two electrodes, which are separated from each other and electrically coupled to mounting pads, each positioned on a frame, and the electrodes are arranged to generate an electric field between at least two surfaces of the resonator plate on both sides of the nodal plane.

[0016] Preferably, the first electrode and the second electrode are arranged on the resonator plate such that when the first electrode and the second electrode are coupled to an AC voltage to generate an AC electric field between the two electrodes, alternating deformation occurs in the resonator plate along the width of the resonator plate.

[0017] Preferably, the first anchoring portion extends from the first side of the resonator plate to the first arm of the C-shaped portion of the frame, and the second anchoring portion extends from the second side of the resonator plate to the second arm of the C-shaped portion of the frame.

[0018] Preferably, the mooring portion is integrated with the resonator plate and the frame.

[0019] Preferably, the resonator plate has a maximum length portion, a transverse edge portion, and a longitudinal edge portion, the maximum length portion being located on both sides of the contact surface at the furthest distance from the contact surface or at a distance close to the longitudinal edge portion.

[0020] Preferably, the resonator plate has a minimum length portion, and the minimum length portion is - A first corner formed between the first anchoring portion and the first transverse edge portion of the resonator plate, - The second corner formed between the second anchoring portion and the second lateral edge of the resonator plate It extends in close proximity to the location between them.

[0021] Preferably, the minimum length portion is at least 90% of the maximum length portion, preferably at least 95% of the maximum length portion, more preferably at least 99% of the maximum length portion.

[0022] Preferably, the minimum length portion is on both sides of the joint surface.

[0023] In some embodiments, the transverse edge portion located between the first end proximate to the mooring portion and the second end proximate to the longitudinal edge forms an inclination angle of 10° or less, preferably 5° or less, with an axis orthogonal to the nodal plane.

[0024] Preferably, the resonator plate is substantially symmetric with respect to its central longitudinal axis (i.e., passing through the joint surface) and symmetric with respect to the central width axis (i.e., orthogonal to the joint surface).

[0025] Preferably, the frame has a certain frame thickness portion, and the resonator thickness portion is included between 25% and 100% of the frame thickness portion, preferably between 25% and 75%, more preferably between 25% and 50%.

[0026] Preferably, the resonator plate has a maximum length portion of 3000 μm or less, preferably 2000 μm or less, preferably 1000 μm or less, more preferably 600 μm or less.

[0027] Preferably, the mooring portion has a length portion included between 10 μm and 300 μm, preferably between 20 μm and 150 μm, more preferably between 50 μm and 100 μm.

[0028] The width portion of the mooring portion is preferably 20% or less of the width portion of the resonator plate.

[0029] The thickness portion of the mooring portion is included between 50% and 150% of the thickness portion of the resonator plate.

[0030] Preferably, the resonator plate has a maximum width portion such that the ratio (width portion) / (maximum length portion) is included between 0.4 and 0.8, preferably between 0.5 and 0.7.

[0031] Preferably, the frame includes an assembly portion, the assembly portion comprising a first assembly pad and a second assembly pad, which are coupled to a first electrode and a second electrode, respectively.

[0032] Preferably, the maximum thickness of the frame is 4000 μm or less, preferably 2500 μm or less, and more preferably 1500 μm or less.

[0033] Preferably, the maximum thickness of the frame thickness portion TF is 200 μm or less, preferably 150 μm or less, and more preferably 120 μm or less.

[0034] According to a second aspect, the present invention relates to a method for manufacturing the above-described resonator, wherein the method is: - Steps to prepare ZT cut wafers, - A step of defining a resonator-shaped floor on a wafer, wherein the resonator-shaped floor includes a resonator frame-shaped floor, a resonator plate-shaped floor, and an anchoring-shaped floor, the anchoring-shaped floor being positioned along the central longitudinal axis of the resonator plate-shaped floor and connecting the lateral side of the resonator plate-shaped floor to the resonator frame-shaped floor, - The steps include obtaining the outer shape of a resonator plate having anchoring portions on both sides of the resonator plate, and etching a portion of the wafer so that the anchoring portions remain integrated with the resonator frame, - At least two separate electrodes are deposited on the resonator plate, such that the first electrode has a main portion positioned on one side of the plane passing through the anchoring portion, and the second electrode has a main portion positioned on the other side of the plane passing through the anchoring portion. Two mounting pads are deposited onto the floor of the resonator frame. ○ A step of depositing connection tracks to connect each electrode to its respective mounting pad, - The step of etching the outer shape of the resonator frame base to obtain a resonator. Includes.

[0035] In one embodiment of the manufacturing method, the method is: - A step of applying a first mask to the surface of the wafer, covering the first surface which is defined to form a frame having a C-shaped portion, and leaving a portion of the wafer surface which is defined to form a thinner, flatter portion of the wafer uncovered, - The step of wet chemical etching the surface of an uncovered wafer to obtain a thinner, flatter portion, - A step of applying a second mask to a flat portion, wherein the second mask has the shape of a resonator plate with a mooring portion, and the mooring portion extends from the resonator plate to the C-shaped portion of the frame, - The remaining uncovered wafer surface is wet chemically etched to form the outline of the resonator plate and anchoring section. Includes.

[0036] In one alternative embodiment, the method for manufacturing a resonator is: - The steps of applying a first mask to the surface of the wafer to cover a first surface defined to form a frame having a C-shaped portion, and leaving a portion of the wafer surface uncovered to form a thinner, flatter portion of the wafer, - The step of wet chemical etching the surface of an uncovered wafer to obtain a thinner, flatter portion, - A step of cutting the outer shape of the resonator plate having an anchoring portion extending from the resonator plate to the C-shaped portion of the frame by femtosecond laser or deep reactive ion etching (DRIE) and It also includes.

[0037] In one alternative embodiment, the step of etching a portion of the wafer to obtain the outer shape of a resonator plate having anchoring portions on both sides of the resonator plate, while keeping the anchoring portions integrated with the resonator frame, is carried out by cutting with a femtosecond laser or deep reactive ion etching (DRIE).

[0038] The objectives, advantages, and features of the present invention will become clear from the following description, which is given with reference to the drawings as merely a non-limiting example. [Brief explanation of the drawing]

[0039] [Figure 1] This is a diagram of one embodiment of a conventional resonator. [Figure 2] This is a top view of one embodiment of a resonator according to the present invention. [Figure 3] This is a side view of one embodiment of a resonator according to the present invention. [Figure 4a] This is a schematic cross-sectional view along the width of a resonator plate having an electrode configuration. [Figure 4b] This is a schematic cross-sectional view along the width of a resonator plate having an electrode configuration. [Figure 4c] This is a schematic cross-sectional view along the width of a resonator plate having an electrode configuration. [Figure 4d] This is a schematic cross-sectional view along the width of a resonator plate having an electrode configuration. [Figure 4e] This is a schematic cross-sectional view along the width of a resonator plate having an electrode configuration. [Figure 4f] This is a schematic cross-sectional view along the width of a resonator plate having an electrode configuration. [Figure 5] This is a schematic cross-sectional view along the width of a resonator plate having a piezoelectric assembly. [Figure 6a] This is a schematic top view of a resonator plate according to an embodiment of the present invention. [Figure 6b] This is a schematic top view of a resonator plate according to an embodiment of the present invention. [Figure 6c] This is a schematic top view of a resonator plate according to an embodiment of the present invention. [Figure 6d] This is a schematic top view of a resonator plate according to an embodiment of the present invention. [Figure 7] This is a simulation image of the deformation of a resonator according to one embodiment of the present invention when exposed to an alternating electric field. [Figure 8a] This is a top view of one embodiment of a preformed resonator. [Figure 8b] This is a top view of one embodiment of a resonator obtained from the manufacturing method according to the first embodiment of the manufacturing method. [Figure 8c]This is a top view of another embodiment of a resonator obtained from the manufacturing method according to the first embodiment of the manufacturing method. [Figure 9a] This is a top view of another embodiment of a preformed resonator. [Figure 9b] This is a top view of a resonator obtained from the manufacturing method according to the third embodiment of the manufacturing method. [Modes for carrying out the invention]

[0040] Unless otherwise stated, the drawings are not to a fixed scale, and it should be noted that other modifications to the resonator design are possible within the scope of the present invention.

[0041] The present invention will be described in more detail below, with reference to Figures 2 and 3, which illustrate one embodiment of the resonator 200. The resonator 200 is - A resonator plate 201 having a thickness portion TR, a lateral edge portion and a length-direction edge portion, a maximum length portion LR1 and a width portion WR, and a resonator plate 201 that is a ZT-cut quartz crystal, - A frame 202 having a C-shaped portion 203 The C-shaped portion 203 comprises a first arm 204 and a second arm 205 that at least partially extend around the transverse edge of the resonator plate, and each arm 204, 205 is connected to the resonator plate by anchoring portions 206a, 206b.

[0042] Advantageously, the frame is made from quartz. Preferably, the anchoring part is also made from quartz. To facilitate fabrication, the entire resonator 200 is fabricated as a single unit from a ZT-cut quartz wafer. A certain number of resonators may be placed on each wafer. The shape of the resonator 200 can be obtained, for example, by wet chemical etching or deep reactive ion etching, or by the method described in International Patent No. 2013 / 092920, or by femtosecond laser-induced chemical etching as described by Linden et al., Microsystems & Nanoengineering (2023) 9:38.

[0043] When used in relation to the resonator plate, the term <<surface>> refers to the largest surfaces of the resonator plate on both sides of the resonator plate, unless otherwise specified.

[0044] The term <<C-shaped portion>> refers to a part of a frame forming a C, which preferably includes a sub-part, and the sub-part includes a first end and a second end connected to a first arm 204 and a second arm 205 respectively pointing in the same direction. The sub-part, the first arm, and the second arm are preferably straight. Preferably, the sub-part forms a 90° angle with the first arm and the second arm.

[0045] The nodal plane 207 is defined, and the nodal plane 207 is perpendicular to the surface SR of the resonator plate 201, passes through the central longitudinal axis of the resonator plate 201, and the mooring parts 206a, 206b pass through the nodal plane 207. The nodal plane 207 is an imaginary plane intersecting orthogonally to the resonator plate, and the vibration amplitude of the resonator plate is minimum or zero when the resonator plate is oscillating under the influence of an alternating electric field.

[0046] The resonator plate 201 is configured to oscillate on both sides of the nodal plane 207 in the direction of the width WR of the resonator plate 201. The terms <<oscillating>> or <<oscillate>> or <<oscillation>>, in the context of the present invention, refer to the shape change of a plate made of a crystal having piezoelectric properties when subjected to an alternating electric field, and the plate is made to periodically expand and contract along the width on both sides of the nodal plane.

[0047] The C-shaped portion 203 of the frame 202 is spaced apart from the resonator plate 201 so as to prevent the resonator plate 201 from contacting the frame 202 while the resonator plate 201 is oscillating. Preferably, the C-shaped portion

[0048] ​The resonator plate 201 comprises at least a first electrode 208 and a second electrode 209, the first electrode 208 and the second electrode 209 being electrically coupled to a first mounting pad 210 and a second mounting pad 211, respectively, which are separated from each other and positioned on the frame 202. The electrodes are arranged to generate an electric field between at least two surfaces of the resonator plate on both sides of the nodal plane.

[0049] The first electrode 208 and the second electrode 209 are positioned on the resonator plate such that they cause deformation of the resonator plate along its width when the first and second electrodes are coupled to an AC voltage to generate an AC electric field between the two electrodes. The electrode configuration can be optimized to maximize piezoelectric coupling to resonant modes while suppressing unwanted modes.

[0050] Figures 4a to 4f show various possible configurations of electrodes on the resonator plate 201. In Figure 4a, the first electrode 208 is located on the first side of the resonator plate 201 and partially covers the surface of the resonator plate on the first side of the nodal plane 207, and the second electrode 209 is located on the opposite side of the resonator plate 201 and partially covers the surface of the resonator plate on the second side of the nodal plane 207. The first electrode 208 and the second electrode 209 have opposite polarities.

[0051] In Figure 4b, the first electrode 208 is located on the first side of the resonator plate 201 and completely covers the surface of the resonator plate on the first side of the nodal plane 207, while the second electrode 209 is located on the opposite side of the resonator plate 201 and completely covers the surface of the resonator plate on the second side of the nodal plane 207. The first electrode 208 and the second electrode 209 have opposite polarities.

[0052] In Figure 4c, the coupling of the first electrodes 208, 208' is located on both sides of the resonator plate 201, partially covering the surface of the resonator plate on the first side of the nodal plane 207, and the coupling of the second electrodes 209, 209' is located on both sides of the resonator plate 201, partially covering the surface of the resonator plate on the second side of the nodal plane 207. The coupling of the first electrodes 208, 208' must have the same polarity and be separated from the coupling of the second electrodes 209, 209' by a gap, while both of the second electrodes 209, 209' have opposite polarity to the coupling of the first electrodes 208, 208'.

[0053] In Figure 4d, the first electrode 208 is located on the first side of the resonator plate 201, completely covering the surface of the resonator plate on the first side of the nodal surface 207 and partially covering the surface of the resonator plate on the second side of the nodal surface 207. The second electrode 209 is located on the opposite side of the resonator plate 201, completely covering the surface on the second side of the nodal surface 207 and partially covering the surface of the resonator plate on the first side of the nodal surface 207. The first electrode 208 and the second electrode 209 have opposite polarities.

[0054] In Figure 4e, the first electrode 208 extends from one side of the resonator plate through a recess in the resonator plate to the other side on the first side of the nodal plane 207, and the second electrode 209 extends from the first side of the resonator plate through the opposite recess in the resonator plate to the other side on the other side of the resonator plate on the other side of the nodal plane 207. The first electrode 208 and the second electrode 209 are separated from each other by a gap and have opposite polarities.

[0055] In Figure 4f, the first electrode 208 is located on the first side of the resonator plate 201 and partially covers the surface of the resonator plate on the first side of the nodal plane 207, and the second electrode 209' is located on the same side of the resonator plate 201 and partially covers the surface of the resonator plate on the second side of the nodal plane 207. The first electrode 208 and the second electrode 209' have opposite polarities. A similar configuration can be obtained by placing the electrodes on the second side of the resonator plate 201.

[0056] The first mounting pad 210 and the second mounting pad 211 are configured to be coupled to an AC electric field generator, i.e., an oscillator circuit.

[0057] In the alternative embodiment shown in Figure 5, the piezoelectric assembly is mounted on at least one surface of the resonator plate 201 and extends on both sides of the nodal surface 207. The first piezoelectric assembly comprises a first electrode 208'' across the surface of the resonator plate, a piezoelectric layer 214 across the first electrode 208'', and a second electrode 209'' across the piezoelectric layer 214. With opposite polarity, the first electrode 208'' is coupled to a first mounting pad 210, and the second electrode 209'' is coupled to a second mounting pad 211.

[0058] As shown in Figure 3, the anchoring portions 206a and 206b are positioned on both sides of the resonator plate 201. The first anchoring portion 206a extends from the first arm portion 204 to the resonator plate 201, and the second anchoring portion 206b extends from the second arm portion 205 of the C-shaped portion 203 of the frame 202 to the resonator plate 201. The anchoring portions 206a and 206b are preferably integral with the frame 202 and the resonator plate 201. The anchoring portions 206a and 206b and the resonator plate 201 may have a thickness portion TR that is less than or equal to the thickness portion TF of the frame 202. Preferably, the anchoring portions have a length that falls between 10 μm and 300 μm, preferably between 20 μm and 150 μm, and more preferably between 40 and 100 μm. The width of the anchoring portions is preferably 25% or less of the width of the resonator plate. The width of the mooring portion is between 50% and 150% of the thickness of the resonator plate. In a preferred embodiment, the mooring portion has a length between 40 μm and 100 μm, a width 20% shorter than the width of the resonator plate, and a thickness between 80% and 120% of the thickness of the resonator plate, preferably about 100% of the thickness of the resonator plate.

[0059] The first electrode 208 or the pair of first electrodes 208, 208' is connected to the first assembly pad 210 by passing the wiring or signal track through the first mooring section 206a and the frame 202. The second electrode 209 or the pair of second electrodes 209, 209' is connected to the second assembly pad 211 by passing the wiring or signal track through the second mooring section 206b and the frame 202. The term "passing through" includes passing over the surface of the mooring section or the frame, and the wiring or signal track may optionally be insulated by a sufficient insulating layer known to those skilled in the art.

[0060] The first electrode 208, or the pair of the first electrodes 208, 208', the second electrode 209, or the pair of the second electrodes 209, 209', are provided on the resonator plate 201 by partially coating the resonator plate with metal, for example by chemical deposition, physical deposition, vacuum deposition, sputtering, or any other sufficient method known to those skilled in the art. The electrodes may be made from any metal or alloy, but are not limited to copper, zinc, chromium / gold, or platinum.

[0061] To minimize the coupling between the resonator and its exterior (frame, package), the thickness of the resonator plate 201 and the anchoring parts 206a and 206b are reduced relative to the frame.

[0062] The resonator plate 201 has a thickness TR which can be between 25 μm and 100 μm, preferably a thickness TR of 75 μm or less, or 50 μm or less.

[0063] The mooring sections 206a and 206b may have the same thickness as the resonator plate 201.

[0064] Reducing the thickness of the resonator plate 202 and the anchoring parts 206a and 206b brings the following advantages: - The thickness / width ratio of plate 201 is reduced, improving the mode shape and enabling a smaller footprint. - The moving mass relative to the frame 202 is reduced, and the transmission of residual motion from the plate 201 to the frame 202 (effect of contact) is reduced. - The smaller cross-section of the mooring sections 206a and 206b improves separation.

[0065] Although the mooring sections 206a and 206b join the resonator plate 201 at the nodal surface 207, the mooring sections 206a and 206b alter the effective shape of the resonator plate 201, and therefore its frequency-temperature behavior. This alteration can be compensated for by altering the shape of the resonator plate 201 such that it has a second length section LR2 that is shorter than the maximum length section LR1 of the resonator plate 201, and the second length section LR2 is -A first corner formed between the first mooring portion and the first transverse edge portion of the resonator plate, - The second corner formed between the second mooring portion and the second transverse edge of the resonator plate It extends in close proximity to the location between them.

[0066] In the context of this specification, the term "proximity" refers to a distance where the shortest distance from the lateral edge of the resonator plate to the anchoring portion is at most 25%.

[0067] The second length portion LR2 is preferably the shortest length portion of the resonator plate and is at least 90% of the maximum length portion LR1 of the resonator plate 201, preferably at least 95% of the maximum length portion LR1, and more preferably at least 99% of the maximum length portion LR1.

[0068] The resonator plate 201 is substantially symmetric with respect to its central width axis MW and its central longitudinal axis (or nodal plane 207). It should be understood that "substantially symmetric" may require a slight deviation from perfect geometric symmetry to compensate for the slight asymmetric residue formed due to anisotropic etching and etching residue resulting from the wet chemical etching process.

[0069] The longest portion LR1 of the resonator plate is advantageously located at or near the longitudinal edge of the resonator plate, for example, at a distance of less than 10% of the width of the plate to the longitudinal edge. In this context, the term "distance near the longitudinal edge" preferably refers to a distance of 50% or less of the distance from the nodal surface to the longitudinal edge.

[0070] Examples of embodiments of a resonator plate having an anchoring portion are shown in Figures 6a to 6c. In Figure 6a, the corners of the plate and the corners between the transverse edges and the anchoring portion are acute angles. In Figure 6b, the corners between the longitudinal edges and the transverse edges are chamfered. In Figure 6c, the corners between the anchoring portion and the transverse edges may include etching residue, so that the shortest length portion LR2 of the resonator plate is slightly away from the anchoring portion but still close to it.

[0071] Figure 6d shows an alternative embodiment of a resonator plate having a mooring portion, in which the lateral edge of the resonator plate forms a notch between a portion of the resonator plate having the maximum length portion LR1 and the mooring portions 206a and 206b, forming a second portion of the minimum length portion LR2.

[0072] The frame 202 has a frame thickness portion TF, and the resonator thickness portion TR is between 25% and 100% of the frame thickness portion TF, preferably between 25% and 75%, preferably between 25% and 60%, and more preferably between 30% and 50%.

[0073] Advantageously, the maximum thickness of the frame thickness portion TF is 200 μm or less, preferably 150 μm or less, and more preferably 120 μm or less.

[0074] The resonator plate 201 has a maximum length portion of 300 μm or less, preferably 2000 μm or less, preferably 1000 μm or less, and more preferably 600 μm or less, and has a width portion / length portion ratio that falls within 0.4 to 0.8, preferably 0.5 to 0.7.

[0075] The frame 202 includes an assembly portion 212 comprising a first assembly pad 210 and a second assembly pad 211, the assembly portion 212 extending substantially parallel to the first arm 204 and the second arm 205 of the C-shaped portion 203, the assembly portion 212 connecting to the C-shaped portion 203 and forming a notch 213 together with the C-shaped portion 203, as shown in Figure 2. Alternatively, the assembly portion is located on the C-shaped portion. For example, the first assembly pad may be assembled on the first arm opposite the first mooring portion, and the second assembly pad opposite the second mooring portion may be assembled on the second arm. In another embodiment, the first and second assembly pads may be assembled on a portion of the frame joining the first and second arms.

[0076] The maximum length of frame 202 is 4000 μm or less, preferably 2500 μm or less, preferably 1500 μm or less, and more preferably 1500 μm or less.

[0077] The frame 202 is rectangular in shape, and its corners are chamfered to minimize damage that could result from having sharp corners while operating the resonator. The resonator plate 201 may also have chamfered corners for the same reason.

[0078] The resonator plate 201, frame 202, and anchoring parts 206a and 206b can be obtained by photolithography manufacturing techniques known in the art, such as wet chemical etching techniques, or deep reactive ion etching techniques, or combinations thereof, or combinations thereof with laser cutting.

[0079] In a second aspect of the present invention, the method for manufacturing a resonator according to the first embodiment is: -The steps include preparing a ZT-cut quartz wafer, applying a first mask to the surface of the wafer, covering the first surface which is defined to form a frame 202 having a C-shaped portion, and leaving a portion of the wafer surface which is defined to form a thinner, flatter portion 199 of the wafer uncovered, - A step of wet chemical etching the surface of an uncovered wafer to obtain a thinner flat portion 199, - A step of applying a second mask to the flat portion 199, wherein the second mask has the shape of a resonator plate with a mooring portion, and the mooring portion extends from the resonator plate-shaped portion to the C-shaped portion of the frame 202, - The remaining uncovered wafer surface is wet chemically etched to form the outline of the resonator plate and anchoring section. Includes.

[0080] Figure 8a shows a preformed resonator obtained by wet chemical etching. The preformed resonator comprises a frame 202 and a wet-etched flat portion 199 having a substantially constant thickness that is thinner than the thickness of the frame 202. Due to the anisotropy of wet chemical etching, the preformed resonator may further comprise an intermediate portion 216 whose thickness gradually changes between the frame 202 and the flat portion 199.

[0081] Figure 8b shows one embodiment of a resonator obtained by the manufacturing method according to the first embodiment, which includes the step of wet chemical etching the flat portion 199 of the preformed resonator described above in Figure 8a to form a resonator plate 201 and anchoring portions 206a, 206b. To obtain a well-defined shape, it is necessary to form a minimum gap 215 width between the resonator plate 201 and the intermediate portion 216. For example, the minimum gap has a width greater than 20 μm, preferably at least 50 μm, and more preferably at least 75 μm. Advantageously, the resonator plate 201 thus obtained has a smaller area compared to the initial area of ​​the flat portion 199, ensuring a constant thickness of the resonator plate 201 and minimizing its defects.

[0082] In a second embodiment, the method for manufacturing a resonator is as follows: -The steps include preparing a ZT-cut quartz wafer, applying a first mask to the surface of the wafer, covering the first surface which is defined to form a frame 202 having a C-shaped portion, and leaving a portion of the wafer surface which is defined to form a thinner, flatter portion 199 of the wafer uncovered, - A step of cutting the outer shape of the resonator plate 201 having anchoring portions 206a and 206b that extend from the resonator plate to the C-shaped portion of the frame 202 by femtosecond laser or deep reactive ion etching (DRIE) and Includes.

[0083] Figure 8c shows an embodiment of a resonator obtained by a manufacturing method according to a second embodiment, which includes cutting a flat portion 199 of the preformed resonator in Figure 8a by deep reactive ion etching (DRIE) or a femtosecond laser to form a resonator plate 201 and anchoring portions 206a, 206b. The cutting of the flat portion 199 to form the resonator plate 201 and anchoring portions 206a, 206b may be limited to forming the outer shape of the resonator plate and anchoring portions, and it is not necessary to remove the remaining flat portion 199b which will be attached to the intermediate portion 216. DRIE or a femtosecond laser allows for cutting of a well-defined shape, and it is sufficient to leave a gap 215 of at least about 1 μm, preferably at least about 5 μm, around the resonator plate 201 and anchoring portions 206a, 206b for proper oscillation of the plate. Advantageously, the resulting resonator plate 201 has a smaller area compared to the initial area of ​​the flat portion 199, ensuring a constant thickness of the resonator plate 201 and minimizing its defects.

[0084] In one aspect of the present invention, the method for manufacturing a resonator according to the third embodiment is: - Steps to prepare ZT cut quartz wafers, - A step of cutting the outer shape of the resonator plate 201 having anchoring portions 206a and 206b extending from the resonator plate to the C-shaped portion of the frame 202 by femtosecond laser or deep reactive ion etching. Includes.

[0085] Figure 9a shows a preformed resonator according to another embodiment, which comprises a frame 202 and a flat portion 199a having the same thickness as the frame 202, or the flat portion 199a may be made thinner than the thickness of the frame 202 by a physical etching method such as DRIE or femtosecond laser treatment, resulting in a frame side wall that forms substantially right angles with the flat portion 199. No etching residue is formed by this technique, and the outer shapes of the resonator plate 201 and the anchoring portions 206a, 206b are cut out by DRIE or femtosecond laser, leaving a small gap between the frame 202 and the group of resonator plates 201 and anchoring portions 206a, 206b, except for the ends of the anchoring portions attached to the frame 202. For proper oscillation of the plate, it is sufficient to leave a gap 215 of at least about 1 μm, preferably at least about 5 μm, around the resonator plate 201 and the anchoring portions 206a, 206b.

[0086] Any one of the above manufacturing methods may include the step of forming a notch within the frame in order to obtain the assembly portion and the C-shaped portion.

[0087] In any of the manufacturing methods described above, multiple resonators can be fabricated on the same wafer. Advantageously, the deposition of electrodes onto the resonator plate, and the deposition of wiring and mounting pads onto the frame, can be performed while the multiple resonators are on the same wafer. Then, each resonator on the same wafer can be separated from each other, preferably by a femtosecond laser or DRIE.

[0088] Frequency tuning can be achieved by the deposition or removal of mass bodies, for example, by evaporation, sputtering, or laser beam or ion beam etching. Since the distribution of mass bodies onto the resonator plate affects the thermal properties of the resonator plate, fine-tuning of the frequency-temperature behavior is possible by localized removal or deposition of mass bodies. This can be considered a higher-order frequency tuning. While tuning typically acts on mass bodies in a metal layer on the resonator, it can, in principle, be performed directly on the quartz crystal.

[0089] In an indefinite example according to the present invention, the resonator comprises a resonator plate 201 and a frame 202. The frame 202 is a rectangle measuring 1400 μm × 580 μm and has a thickness of 127 μm. The resonator plate has a thickness of 50 μm, a width of 330 μm, a maximum length LR1 of 570 μm at the edge of the resonator plate, and a second length LR2 of 560 μm along the axis in the direction of the central length. The frame comprises a C-shaped portion 203 having a first arm portion 204 and a second arm portion 205, and a first mooring portion 206a and a second mooring portion 206b connect the resonator plate 201 to the frame 202. The mooring portions 206a, 206b and the resonator plate 201 have a thickness of 50 μm. Both mooring portions 206a and 206b have a width of 50 μm and a length of 90 μm. As described above in relation to the embodiment of Figure 4a, the resonator plate 201 comprises a pair of first electrodes 208, 208' connected to the first mounting pad 210, and a second pair of electrodes 209, 209' connected to the second mounting pad 211.

[0090] The mounting pad is positioned on the mounting portion of the frame, which is connected to the C-shaped portion by the handle. The handle lies in the same plane as the mounting portion and the C-shaped portion, forming a notch between the mounting portion and the C-shaped portion.

[0091] Figure 7 shows a simulation image of a resonator according to one embodiment of the present invention, where the shape is optimized to minimize the coupling of the residual portion to the anchoring portion and the frame. In the simulation image, darker regions represent the regions of the resonator plate, and the tensile deformation of the resonator plate 201 on both sides of the nodal surface 207 is most important. Brighter regions represent regions where the deformation is minimal. As shown in the figure, in the regions of the resonator plate 201 on the anchoring portions 206a and 206b, close to the nodal surface, the vibration amplitude is minimal or zero. Therefore, during use of the resonator, i.e., when the resonator plate is exposed to an AC electric field, the regions of the resonator plate 201 near the anchoring portions 206a and 206b and the nodal surface 207 do not move relative to the frame 202.

[0092] According to the present invention, by providing a resonator plate that is easily machined, has a simpler shape, and offers more stable fixing, it is possible to reduce the size of the ZT-cut quartz resonator. [Explanation of symbols]

[0093] 100 Conventional resonators 101 First resonator plate 102 Second resonator plate 103 Resonator arm 104 Assembly part 105 Suspended arm 199 Flat portion of a preformed resonator 199b Residual portion of the flat section 200 resonator 201 Resonator plate 202 slots 203 C-shaped part 204 First Arm 205 Second Arm 206a / 206b Mooring area 207 Nodal plane 208 First electrode 209 Second electrode 208' Third electrode 209' Fourth electrode 210 First assembly pad 211 Second assembly pad 212 Assembly part 213 Notch 214 Piezoelectric layer 215 Space between the frame and the resonator plate 216 Etching residue Thickness section of the TR resonator TF frame thickness Surface of the SR resonator SR1 The first side of SR SR2 The second side of SR LR1 resonator, maximum length section Second length section of the LR2 resonator Width section of WR resonator WR resonator center width

Claims

1. A resonator 200, wherein the resonator 200 is - A resonator plate 201 having a thickness portion TR, a maximum length portion LR1 and a width portion WR, and a surface SR, wherein the resonator plate 201 is a ZT cut quartz crystal, - A frame 202 having a C-shaped portion 203 The resonator 200 comprises a C-shaped portion 203 which includes a first arm portion 204 and a second arm portion 205 that at least partially extend around the width edge of the resonator plate, and each of the arms 204 and 205 is connected to the resonator plate by anchoring portions 206a and 206b.

2. The resonator according to claim 1, wherein a nodal surface 207 is defined, the nodal surface 207 is perpendicular to the surface SR of the resonator plate 201 and passes through the central longitudinal axis of the resonator plate 201, and the anchoring portions 206a and 206b pass through the nodal surface 207.

3. The resonator according to claim 2, wherein the resonator plate 201 is configured to oscillate on both sides of the nodal surface 207 in the direction of the width portion WR of the resonator plate 201, and the C-shaped portion 203 of the frame 202 is spaced apart from the resonator plate 201 so as to prevent the resonator plate 201 from coming into contact with the frame 202 while the resonator plate 201 is oscillating.

4. The resonator according to claim 2, wherein the resonator plate 201 comprises at least a first electrode 208 and a second electrode 209, the first electrode 208 and the second electrode 209 being separated from each other and electrically coupled to a first mounting pad 210 and a second mounting pad 211, respectively, which are located on the frame 202, and the electrodes 208 and 209 are arranged on the resonator plate 201 to generate an electric field between at least two surfaces of the resonator plate on both sides of the nodal surface 207.

5. The resonator according to claim 1, wherein the first electrode 208 and the second electrode 209 are arranged on the resonator plate 201 such that when the first electrode and the second electrode are coupled to an AC voltage to generate an AC electric field between the two electrodes, the resonator plate is deformed along the width portion of the resonator plate.

6. The resonator according to claim 1, wherein the anchoring portions 206a and 206b are integral with the resonator plate 201 and the frame 202, the first anchoring portion 206a extends between the resonator plate 201 and the first arm portion 204 of the C-shaped portion 203, and the second anchoring portion 206b extends between the resonator plate 201 and the second arm portion 205 of the C-shaped portion 203.

7. The resonator plate 201 is provided with a minimum length portion LR2, and the minimum length portion LR2 is - A first corner formed between the first mooring portion and the first transverse edge portion of the resonator plate, - The second corner formed between the second mooring portion and the second lateral edge portion of the resonator plate and The resonator according to claim 1, which extends in close proximity to the location between the two.

8. The resonator according to claim 7, wherein the minimum length portion LR2 is at least 90% of the maximum length portion LR1, preferably at least 95% of the maximum length portion LR1, and more preferably at least 98% of the maximum length portion LR1.

9. The resonator according to claim 2, wherein the resonator plate 201 is substantially symmetric with respect to the central width axis MW of the resonator plate 201 and with respect to the central longitudinal axis of the resonator plate 201 that coincides with the nodal surface 207.

10. The resonator according to claim 1, wherein the frame 202 has a frame thickness portion TF, the resonator has a resonator thickness portion TR, the resonator thickness portion TR is between 25% and 100% of the frame thickness portion TF, preferably between 25% and 75%, more preferably between 25% and 50%, and preferably the maximum thickness of the frame thickness portion TF is 200 μm or less, preferably 150 μm or less, more preferably 120 μm or less.

11. The resonator according to claim 1, wherein the resonator plate 201 has a maximum length of 2500 μm or less, preferably 1000 μm or less, and more preferably 600 μm or less.

12. The resonator according to claim 1, wherein the resonator plate 201 has a maximum width WR such that the ratio of (maximum width WR) / (maximum length LR1) is between 0.4 and 0.8, preferably between 0.5 and 0.

7.

13. The resonator according to claim 1, wherein the frame 202 comprises an assembly portion 212 having a first assembly pad 210 and a second assembly pad 211, the assembly portion 212 extending substantially parallel to the arms 204, 205 of the C-shaped portion 203, the assembly portion 212 is connected to the C-shaped portion 203 and together with the C-shaped portion 203 forms a notch 213.

14. The aforementioned mooring section is, Lengths between 10 μm and 300 μm, preferably between 20 μm and 150 μm, more preferably between 40 and 100 μm, and / or A width that is 25% or less of the width of the resonator plate, and / or The width included in the range of 50% to 150% of the thickness of the resonator plate. The resonator according to claim 1, having the following features.

15. A method for manufacturing a ZT cut resonator, wherein the method is: Steps to prepare ZT cut wafers, A step of defining a resonator-shaped floor on the wafer, wherein the resonator-shaped floor includes a resonator frame-shaped floor, a resonator plate-shaped floor, and a mooring-shaped floor, the mooring-shaped floor being positioned along the central longitudinal axis of the resonator plate-shaped floor and connecting the lateral side of the resonator plate-shaped floor to the resonator frame-shaped floor, The process involves obtaining the outer shape of the resonator plate having anchoring portions on both sides of the resonator plate, and etching a portion of the wafer so that the anchoring portions remain integrated with the resonator frame, At least two separate electrodes are deposited on the resonator plate, such that the first electrode has a main portion positioned on one side of the plane passing through the anchoring portion, and the second electrode has a main portion positioned on the other side of the plane passing through the anchoring portion. Two assembly pads are deposited onto the resonator frame floor, The steps include: depositing connection tracks to connect each electrode to its respective mounting pad; The steps include etching the outer shape of the resonator frame base to obtain a resonator, and Methods that include...

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