ZT-quartz resonator

Abstract

One aspect of the invention relates to a resonator comprising:-a resonating plate having a thickness and a surface, the surface having a maximum length and width, where the resonating plate is ZT cut quartz; and-a frame comprising a C-shaped portion comprising a first arm and a second arm, the first and second arms extending at least partially around a lateral edge of the resonating plate, where the first and second arms are each connected to the resonating plate by means of tethers.

Description

Technical Field

[0001] The present invention relates to a miniature quartz resonator made of ZT-cut quartz by (machine) processing and configured to oscillate in a length-extending profile mode along one edge of a resonant plate. Background Technology

[0002] Existing technical documents such as FR2435855, FR2521782, and FR2634067 describe ZT-quartz resonators.

[0003] The cut angle of the ZT-resonator is chosen to obtain a near-zero first-order frequency-temperature coefficient, with negligible correlation to surface shear modes and extension modes along the other edge of the resonator. Different ZT cuts with similar characteristics can be obtained by first rotating the Z-axis by an angle ψ, then by rotating the X'-axis by φ, and then by rotating the Z'-axis by an angle θ perpendicular to the plane of the resonator. A common cut is ψ = 90°, so the second rotation would be φ = 26.5° around X' = Y, and θ = 20° around Z'. This cut is called ZTY. The simplest cut in the ZT-series might be a simple rotation of φ = 24° around X, called ZTX.

[0004] By appropriately selecting the aspect ratio of the resonant plate, the second-order temperature coefficient also becomes zero due to the residual connection between the (extended) modes. Therefore, a third-order frequency-temperature characteristic is obtained. Compared to the AT-cut resonator, the third-order temperature coefficient is approximately twice as small. Furthermore, for a given frequency, the ZT can be made much smaller than the AT.

[0005] For a typical ZT, its resonant frequency is between 1 and 20 MHz.

[0006] Because the contour pattern is highly sensitive to impacts acting on its surroundings, the manufacturing process must ensure precise shape control. Furthermore, anchoring must be handled with extreme care. The anchoring device secures the resonator in place while ensuring good decoupling from the package to maintain the high quality factor and excellent thermal performance of the ZT-resonator.

[0007] The previous anchoring was achieved using a resonant arm, which minimized mode interference. Figure 1 However, the geometry of the anchoring device is also very critical.

[0008] Figure 1An example of a prior art ZT-cut quartz resonator 100 is shown, comprising a first resonant plate 101 and a second resonant plate 102 connected together by a resonant arm 103. The resonant arm 103 is connected to a mounting portion 104 via a cantilever 105. The first resonant plate 101, the second resonant plate 102, the resonant arm 103, the mounting portion 104, and the cantilever 105 are all coplanar. Each resonant plate has a first electrode (not shown) on one side and a second electrode (not shown) on the opposite side of each resonant plate, wherein the two electrodes are electrically connected to an alternating electric field generator (not shown). The first and second electrodes are designed and arranged such that the two resonant plates oscillate in their width direction, as indicated by the dashed arrows. The two resonant plates are arranged equidistantly on both sides of the resonant arm and the mounting portion. The mounting portion is arranged between the two resonant plates to minimize the width of the resonator. Because the two resonant plates are connected by the resonant arm, the length 106 of the resonator is relatively long, for example, 3850 μm, while the width 107 of the resonant plates is also relatively long, for example, 2024 μm.

[0009] ZT-cut quartz resonators require miniaturization; however, the complex design of such resonators makes them difficult to fabricate in smaller sizes, limiting miniaturization. Furthermore, the resonant arm and support arm must be sufficiently wide to withstand the mechanical constraints imposed by the bulky resonant plate. The symmetry of the resonant structure must be well controlled to minimize energy loss at the mounting and thus reduce attenuation. Summary of the Invention

[0010] The present invention aims to provide an alternative design for ZT-cut quartz resonators to overcome the challenging limitations associated with miniaturization of such resonators.

[0011] According to the first aspect, the resonator includes:

[0012] - A resonant plate, the resonant plate having a certain thickness and surface, the surface having a maximum length and width, wherein the resonant plate is ZT-cut quartz, and

[0013] - A frame comprising a C-shaped portion including a first arm and a second arm extending at least partially around a lateral edge of a resonant plate, wherein both the first arm and the second arm are connected to the resonant plate by means of a tether.

[0014] The resonator defines a nodal plane that is orthogonal to the surface of the resonant plate and passes through the central longitudinal axis of the resonant plate, through which the tether passes.

[0015] Preferably, the resonant plate is configured to oscillate on both sides of the node plane along its width direction, and the C-shaped portion of the frame is spaced apart from the resonant plate to prevent the resonant plate from contacting the frame when the resonant plate oscillates, and to ensure the decoupling of the resonant plate from the frame.

[0016] Preferably, the resonant plate includes at least two electrodes that are separated from each other and electrically connected to mounting pads / mounting pads arranged on a frame, the electrodes being arranged to generate an electric field between at least two surfaces of the resonant plate located on both sides of the node plane.

[0017] Preferably, the first electrode and the second electrode are arranged on the resonant plate such that when the first electrode and the second electrode are connected to an alternating voltage to generate an alternating electric field between the two electrodes, the resonant plate undergoes alternating deformation along its width.

[0018] Preferably, the first tether extends from the first side of the resonant plate to the first arm of the C-shaped portion of the frame, and the second tether extends from the second side of the resonant plate to the second arm of the C-shaped portion of the frame.

[0019] Preferably, these tethers are integrated with the resonant plate and the frame.

[0020] Preferably, the resonant plate has a maximum length, lateral edges, and longitudinal edges, and the maximum length is located at the position furthest from the node plane on both sides of the node plane, or at the position close to the longitudinal edge on both sides of the node plane.

[0021] Preferably, the resonant plate has a minimum length that extends between two locations near the following two:

[0022] - A first corner portion formed between the first tether and the first lateral edge of the resonant plate;

[0023] - The second corner is formed between the second tether and the second lateral edge of the resonant plate.

[0024] Preferably, the shortest length is at least 90% of the maximum length, more preferably at least 95% of the maximum length, and even more preferably at least 99% of the maximum length.

[0025] Preferably, the shortest length is located on both sides of the node plane.

[0026] In some embodiments, the lateral edge located between the first end near the tether and the second end near the longitudinal edge forms an angle of inclination of 10° or less, preferably 5° or less, with respect to the axis orthogonal to the node plane.

[0027] Preferably, the resonant plate is substantially symmetrical about its central longitudinal axis (i.e., the axis through which the node plane passes) and substantially symmetrical about its intermediate width axis (i.e., the axis orthogonal to the node plane).

[0028] Preferably, the frame has a certain frame thickness, such that the resonator thickness is between 25% and 100% of the frame thickness, more preferably between 25% and 75%, and more preferably between 25% and 50%.

[0029] Preferably, the maximum length of the resonant plate is less than or equal to 3000 μm, more preferably 2000 μm or less, more preferably less than or equal to 1000 μm, and more preferably less than or equal to 600 μm.

[0030] Preferably, the length of the tether is between 10 μm and 300 μm, more preferably between 20 μm and 150 μm, and even more preferably between 50 μm and 100 μm.

[0031] The width of the tether is preferably 20% or less of the width of the resonant plate.

[0032] The thickness of the tether is between 50% and 150% of the thickness of the resonant plate.

[0033] Preferably, the resonant plate has a maximum width such that the ratio of (width) to (maximum length) is between 0.4 and 0.8, and more preferably between 0.5 and 0.7.

[0034] Preferably, the frame includes a mounting portion comprising a first mounting pad and a second mounting pad respectively connected to the first electrode and the second electrode.

[0035] Preferably, the maximum length of the frame is less than or equal to 4000 μm, more preferably less than or equal to 2500 μm, and even more preferably less than or equal to 1500 μm.

[0036] Preferably, the maximum thickness of the frame is less than or equal to 200 μm, more preferably less than or equal to 150 μm, and even more preferably less than or equal to 120 μm.

[0037] According to a second aspect, the present invention relates to a method for manufacturing the above-described resonator, wherein the method includes the following steps:

[0038] - We provide ZT-cut wafers;

[0039] - A resonator shape layout is defined on the wafer, wherein the resonator shape layout includes a resonator frame shape layout, a resonator plate shape layout and a tether shape layout, wherein the tether shape layout is positioned along the central longitudinal axis of the resonator plate shape layout and connects the side of the resonator plate shape layout to the resonator frame shape layout.

[0040] - A portion of the wafer is etched to obtain the outline of the resonant plate, which has tethers on both sides and the tethers remain integrated with the resonator frame;

[0041] - Perform the following deposition operations:

[0042] • Deposit at least two separate electrodes on the resonant plate, such that the main portion of the first electrode is arranged on one side of the plane passing through the tether, and the main portion of the second electrode is arranged on the other side of the plane passing through the tether;

[0043] • Two mounting pads are deposited on the resonator frame layout; and

[0044] • Deposition connects each electrode to the corresponding mounting pad via a trace; and

[0045] - Etch the outline of the resonator frame layout to obtain the resonator.

[0046] In one embodiment of the manufacturing method, the method includes the following steps:

[0047] - Apply a first mask to the surface of the wafer to cover the first surface intended to form a frame with a C-shape, leaving a portion of the wafer surface intended to form a thinner planar portion of the wafer uncovered;

[0048] - Perform chemical wet etching on the uncovered surface of the wafer to obtain a thinner planar portion;

[0049] - A second mask is applied to the planar portion, wherein the second mask has the shape of a resonant plate, and a tether extends from the resonant plate shape to the C-shaped portion of the frame; and

[0050] - Chemical wet etching is performed on the remaining uncovered surfaces of the wafer to form the outline of the resonant plate and tether.

[0051] In an optional embodiment, the method of manufacturing the resonator further includes the following steps:

[0052] - Apply a first mask to the surface of the wafer to cover the first surface intended to form a frame with a C-shape, leaving a portion of the wafer surface intended to form a thinner planar portion of the wafer uncovered;

[0053] - Perform chemical wet etching on the uncovered surface of the wafer to obtain a thinner planar portion;

[0054] - The contour of the resonant plate is cut out using a femtosecond laser or deep reactive ion etching (DRIE), with tethers extending from the resonant plate to the C-shaped portion of the frame.

[0055] In one alternative embodiment, a portion of the wafer is etched to obtain the resonant plate profile by cutting with a femtosecond laser or deep reactive ion etching (DRIE), the resonant plate having tethers on both sides and the tethers being integrated with the resonator frame. Attached Figure Description

[0056] The objectives, advantages, and features of the invention will become apparent from the following description, given by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0057] Figure 1 An embodiment of a resonator according to the prior art is shown;

[0058] Figure 2 A top view of an embodiment of a resonator according to the present invention is shown;

[0059] Figure 3 A side view of an embodiment of a resonator according to the present invention is shown;

[0060] Figures 4a to 4f Various schematic cross-sectional views along the width direction of resonant plates with different electrode arrangements are shown;

[0061] Figure 5 A schematic cross-sectional view of a resonant plate with a piezoelectric component along its width is shown.

[0062] Figures 6a to 6d A schematic top view of a resonant plate according to various embodiments of the present invention is shown;

[0063] Figure 7 A simulated image of a resonator deforming under an alternating electric field according to an embodiment of the present invention is shown;

[0064] Figure 8a A top view of one embodiment of the preformed resonator is shown. Figure 8b A top view of one embodiment of a resonator obtained by the manufacturing method according to the first embodiment of the manufacturing method is shown, and Figure 8c A top view of another embodiment of a resonator obtained by the manufacturing method according to the second embodiment of the manufacturing method is shown;

[0065] Figure 9a A top view of another embodiment of the preformed resonator is shown, and Figure 9b A top view of a resonator obtained by the manufacturing method according to the third embodiment of the manufacturing method is shown.

[0066] It should be noted that the accompanying drawings are not drawn to scale, and unless otherwise stated, other variations of the resonator design are possible within the spirit of the invention. Detailed Implementation

[0067] The following will combine Figure 2 and Figure 3 The invention will be described in more detail here, illustrating one embodiment of a resonator 200, which includes:

[0068] - Resonant plate 201, resonant plate 201 has thickness TR and surface SR, surface SR has lateral edge and longitudinal edge, maximum length LR1 and width WR, wherein resonant plate 201 is ZT cut quartz;

[0069] - Frame 202, which includes a C-shaped portion 203, which includes a first arm 204 and a second arm 205, the second arm 205 extending at least partially around the lateral edge of the resonant plate, and wherein each arm 204, 205 is connected to the resonant plate by means of tethers 206a, 206b, respectively.

[0070] Advantageously, the frame is made of quartz. Preferably, the tether is also made of quartz. For ease of manufacture, the entire resonator 200 is integrally formed from a ZT-cut quartz wafer. A certain number of resonators can be arranged on each wafer. The shape of the resonator 200 can be obtained, for example, by chemical wet etching or deep reactive ion etching, or by the method described in document WO2013 / 092920, or by femtosecond laser-induced chemical etching as described by Linden et al. in Microsystems & Nanoengineering (2023) 9:38.

[0071] When the term "surface" is used with respect to a resonator, it refers to the largest surface area of ​​the resonator located on either side of the resonator, unless otherwise specified.

[0072] The term "C-shaped portion" refers to the C-shaped part of the frame, wherein this portion preferably includes a sub-part having a first end and a second end, to which a first arm 204 and a second arm 205, pointing in the same direction, are respectively connected. 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.

[0073] A node plane 207 is defined, which is orthogonal to the surface SR of the resonant plate 201 and passes through the central longitudinal axis of the resonant plate 201, wherein tethering ropes 206a and 206b pass through the node plane 207. The node plane 207 is a virtual plane orthogonal to the resonant plate, in which the vibration amplitude is minimized or zero when the resonant plate oscillates under the influence of an alternating electric field.

[0074] The resonant plate 201 is configured to oscillate along its width WR direction on both sides of the node plane 207. In the context of this invention, the term "oscillation" refers to the shape change of a resonant plate made of a quartz crystal with piezoelectric properties under the action of an alternating electric field, such that the resonant plate periodically extends and contracts along its width on both sides of the node plane.

[0075] The C-shaped portion 203 of the frame 202 is spaced apart from the resonant plate 201 to prevent the resonant plate 201 from contacting the frame 202 when the resonant plate 201 oscillates. Preferably, the distance between the C-shaped portion 203 of the frame and the resonant plate is at least 1 μm, more preferably 10 μm, 20 μm, more preferably at least 50 μm, and more preferably at least 75 μm.

[0076] The resonant plate 201 includes at least a first electrode 208 and a second electrode 209, which are separate from each other and electrically connected to a first mounting pad 210 and a second mounting pad 211 disposed on the frame 202, respectively. These electrodes are arranged to generate an electric field between at least two surfaces of the resonant plate located on both sides of the node plane.

[0077] The first electrode 208 and the second electrode 209 are arranged on a resonant plate such that when the first and second electrodes are connected to an alternating voltage, thereby generating an alternating electric field between the two electrodes, the resonant plate deforms along its width. The electrode configuration can be optimized to maximize piezoelectric coupling with the resonant mode while suppressing unwanted modes.

[0078] Figures 4a to 4f Various possible configurations of the electrodes on the resonant plate 201 are shown. Figure 4a In this configuration, the first electrode 208 is located on the first side of the resonant plate 201 and partially covers the surface of the resonant plate on the first side of the node plane 207; the second electrode 209 is located on the opposite side of the resonant plate 201 and partially covers the surface of the resonant plate on the second side of the node plane 207. The first electrode 208 and the second electrode 209 have opposite polarities.

[0079] exist Figure 4b In this configuration, the first electrode 208 is located on the first side of the resonant plate 201 and completely covers the surface of the resonant plate on the first side of the node plane 207; the second electrode 209 is located on the opposite side of the resonant plate 201 and completely covers the surface of the resonant plate on the second side of the node plane 207. The first electrode 208 and the second electrode 209 have opposite polarities.

[0080] exist Figure 4cIn the resonant plate 201, a pair of first electrodes 208 and 208' are located on both sides of the resonant plate 201, partially covering the surface of the resonant plate on the first side of the node plane 207; a pair of second electrodes 209 and 209' are located on both sides of the resonant plate 201, partially covering the surface of the resonant plate on the second side of the node plane 207. The first electrodes 208 and 208' have the same polarity and must be separated from the second electrodes 209 and 209' by a certain gap. The polarity of the second electrodes 209 and 209' is opposite to that of the first electrodes 208 and 208'.

[0081] exist Figure 4d In this configuration, the first electrode 208 is located on the first side of the resonant plate 201, completely covering the surface of the resonant plate on the first side of the node plane 207, and partially covering the surface of the resonant plate on the second side of the node plane 207. The second electrode 209 is located on the opposite side of the resonant plate 201, completely covering the surface of the resonant plate on the second side of the node plane 207, and partially covering the surface of the resonant plate on the first side of the node plane 207. The first electrode 208 and the second electrode 209 have opposite polarities.

[0082] exist Figure 4e In this design, the first electrode 208 extends from one side of the resonant plate to the other side of the resonant plate through a groove on the first side of the node plane 207, and the second electrode 209 extends from the first side of the resonant plate to the other side of the resonant plate through a corresponding groove on the other side of the node plane 207. The first electrode 208 and the second electrode 209 are separated from each other by a certain gap and have opposite polarities.

[0083] exist Figure 4f In this arrangement, the first electrode 208 is located on the first side of the resonant plate 201 and partially covers the surface of the resonant plate on the first side of the node plane 207; the second electrode 209' is located on the same side of the resonant plate 201 and partially covers the surface of the resonant plate on the second side of the node plane 207. The first electrode 208 and the second electrode 209' have opposite polarities. A similar arrangement can be obtained by placing these electrodes on the second side of the resonant plate 201.

[0084] The first mounting pad 210 and the second mounting pad 211 are configured to be connected to an alternating electric field generator, i.e., an oscillator circuit.

[0085] In such Figure 5In the alternative embodiment shown, the piezoelectric assembly is mounted on at least one surface of the resonant plate 201 and extends on both sides of the node plane 207. The first piezoelectric assembly includes a first electrode 208” located on the surface of the resonant plate, a piezoelectric layer 214 located on the first electrode 208”, and a second electrode 209” located on the piezoelectric layer 214. 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 with opposite polarity.

[0086] like Figure 3 As shown, tethers 206a and 206b are arranged on both sides of the resonant plate 201. The first tether 206a extends from the first arm 204 to the resonant plate 201, and the second tether 206b extends from the second arm 205 of the C-shaped portion 203 of the frame 202 to the resonant plate 201. The tethers 206a and 206b are preferably integral with the frame 202 and the resonant plate 201. The thickness TR of the tethers 206a and 206b and the resonant plate 201 can be equal to or less than the thickness TF of the frame 202. Preferably, the length of the tethers is between 10 μm and 300 μm, more preferably between 20 μm and 150 μm, and more preferably between 40 μm and 100 μm. The width of the tethers is preferably 25% or less of the width of the resonant plate. The thickness of the tethers is between 50% and 150% of the thickness of the resonant plate. In a preferred embodiment, the length of the tether is between 40 μm and 100 μm, the width is less than 20% of the width of the resonant plate, and the thickness is between 80% and 120% of the thickness of the resonant plate, preferably about 100% of the thickness of the resonant plate.

[0087] The first electrode 208 or a pair of first electrodes 208, 208' is connected to the first mounting pad 210 via wiring or signal traces passing through the first tether 206a and the frame 202. The second electrode 209 or a pair of second electrodes 209, 209' is connected to the second mounting pad 211 via wiring or signal traces passing through the second tether 206b and the frame 202. The term "passing through" also includes passing through the surface of the tether or frame, and the wiring or signal traces may optionally be insulated with a suitable insulating layer known to those skilled in the art.

[0088] The first electrode 208 or a pair of first electrodes 208, 208' and the second electrode 209 or a pair of second electrodes 209, 209' are disposed on the resonant plate 201 by local metallization of the resonant plate 201, for example by chemical vapor deposition, physical vapor deposition, vacuum deposition, sputtering, or any other suitable method known to those skilled in the art. These electrodes may be made of any metal or alloy, such as, but not limited to, copper, zinc, chromium / gold, or platinum.

[0089] To minimize the coupling between the resonator and its external components (frame, package), the thickness of the resonator plate 201 and the tethers 206a, 206b is reduced relative to the frame.

[0090] The thickness TR of the resonant plate 201 can be between 25 μm and 100 μm, advantageously less than or equal to 75 μm, or less than or equal to 50 μm.

[0091] The thickness of the tethering ropes 206a and 206b can be the same as the thickness of the resonant plate 201.

[0092] By reducing the thickness of the resonant plate 202 and the thickness of the tethering ropes 206a and 206b, the following advantages can be obtained:

[0093] - The thickness / width ratio of the resonant plate 201 is reduced, thereby improving the mode shape and achieving a smaller footprint;

[0094] - The reduced moving mass relative to frame 202 reduces residual motion transmission (tactile effect) from resonant plate 201 to frame 202;

[0095] - Due to the smaller cross-section of tethers 206a and 206b, decoupling is improved.

[0096] Although tethers 206a and 206b are connected to the resonant plate 201 at the node plane 207, they alter the effective shape of the resonant plate 201, thereby changing its frequency-temperature characteristics. This can be compensated for by changing the shape of the resonant plate 201 so that it has a second length LR2 shorter than its maximum length LR1, which extends between two locations near the following two:

[0097] - The first corner formed between the first tether and the first lateral edge of the resonant plate; and

[0098] - The second corner is formed between the second tether and the second lateral edge of the resonant plate.

[0099] In the context of this application, the term "nearby" refers to a distance of up to 25% of the longest distance between the tether and the lateral edge of the resonator.

[0100] The second length LR2 is preferably the shortest length of the resonant plate, and is at least 90% of the maximum length LR1 of the resonant plate 201, preferably at least 95% of the maximum length LR1, and more preferably at least 99% of the maximum length LR1.

[0101] The resonant plate 201 is substantially symmetrical about its central width axis MW and central longitudinal axis (or nodal plane 207). “Substantially symmetrical” should be understood as: in order to compensate for the small asymmetric residues formed by etching residues generated in anisotropic etching and chemical wet etching processes, a small deviation relative to perfect geometric symmetry may be required.

[0102] The maximum length LR1 of the resonant plate is advantageously located at the longitudinal edge of the resonant plate, or at a distance from the longitudinal edge, for example, at a distance less than 10% of the width of the resonant plate. In this context, "at a distance from the longitudinal edge" preferably means a distance of 50% or less of the distance between the longitudinal edge and the node plane.

[0103] Figures 6a to 6c An example of an embodiment with a resonant plate having tethering is shown. Figure 6a In the middle, all corners of the resonant plate and all corners between the lateral edges and the tethering rope are sharp angles. Figure 6b In the middle, the corners between the longitudinal and lateral edges are chamfered. Figure 6c In the middle, the corners between the tether and the lateral edge may contain etching residue, so the shortest length LR2 of the resonator plate is slightly off from the tether, but still located near the tether.

[0104] Figure 6d An alternative embodiment of a resonant plate with tethers is shown, wherein the lateral edge of the resonant plate forms a notch between the portion of the resonant plate having the maximum length LR1 and the tethers 206a, 206b, thereby forming a second portion having the minimum length LR2.

[0105] The frame 202 has a frame thickness TF, and the resonator thickness TR is between 25% and 100% of the frame thickness TF, preferably between 25% and 75%, more preferably between 25% and 60%, and more preferably between 30% and 50%.

[0106] Advantageously, the maximum thickness TF of the frame is less than or equal to 200 μm, preferably less than or equal to 150 μm, and more preferably less than or equal to 120 μm.

[0107] The maximum length of the resonant plate 201 is less than or equal to 3000 μm, preferably 2000 μm or less, preferably less than or equal to 1000 μm, more preferably less than or equal to 600 μm, and the width / length ratio is 0.4 to 0.8, preferably 0.5 to 0.7.

[0108] Frame 202 includes a mounting portion 212, which includes a first mounting pad 210 and a second mounting pad 211. The mounting portion 212 extends substantially parallel to the first arm 204 and the second arm 205 of the C-shaped portion 203, and is connected to the C-shaped portion 203, forming a recess 213 with the C-shaped portion 203, as shown below. Figure 2 As shown. Optionally, the mounting portion is located on the C-shaped portion. For example, a first mounting pad may be mounted on the first arm and opposite the first tether, and a second mounting pad may be mounted on the second arm and opposite the second tether. In another embodiment, the first and second mounting pads may be mounted on the frame portion connecting the first and second arms.

[0109] The maximum length of frame 202 is less than or equal to 4000 μm, preferably less than or equal to 2500 μm, more preferably less than or equal to 1500 μm, and even more preferably less than or equal to 1500 μm.

[0110] The frame 202 can be rectangular in shape, and its corners can be chamfered to minimize damage caused by sharp corners during resonator operation. For the same reason, the corners of the resonator plate 201 can also be chamfered.

[0111] The resonant plate 201, frame 202 and tethers 206a, 206b can be obtained by photolithography manufacturing techniques known in the art, such as chemical wet etching or deep ion reactive etching, or a combination of these techniques, or a combination of these techniques with laser cutting.

[0112] In a second aspect of the invention, a method for manufacturing a resonator according to the first embodiment includes the following steps:

[0113] - Provide ZT-cut quartz wafers, apply a first mask to the surface of the wafer to cover the first surface intended to form a frame 202 with a C-shaped portion, and leave a portion of the wafer surface intended to form a thinner planar portion 199 of the wafer uncovered;

[0114] - Perform chemical wet etching on the uncovered surface of the wafer to obtain a thinner planar portion 199;

[0115] - A second mask is applied to the planar portion 199, wherein the second mask has the shape of a resonant plate, and a tether extends from the resonant plate shape to the C-shaped portion of the frame 202; and

[0116] - Chemical wet etching is performed on the remaining uncovered surfaces of the wafer to form the outline of the resonant plate and tether.

[0117] Figure 8aA preformed resonator obtained by chemical wet etching is shown. The preformed resonator includes a frame 202 and a wet-etched planar portion 199, the thickness of which is substantially constant and less than the thickness of the frame 202. Due to the anisotropy of chemical wet etching, the preformed resonator may also include an intermediate portion 216 of gradually varying thickness located between the frame 202 and the planar portion 199.

[0118] Figure 8b An embodiment of a resonator obtained by a manufacturing method according to the first embodiment is shown, wherein the method includes combining the above-described... Figure 8a The planar portion 199 of the preformed resonator described is subjected to a chemical wet etching process to form the resonant plate 201 and tethers 206a, 206b. To obtain a well-defined shape, a minimum gap 215 needs to be formed between the resonant plate 201 and the intermediate portion 216. For example, the width of this minimum gap is greater than 20 μm, preferably at least 50 μm, and more preferably at least 75 μm. Advantageously, the area of ​​the resulting resonant plate 201 is smaller than the initial area of ​​the planar portion 199 to ensure a constant thickness of the resonant plate 201 and minimize its defects.

[0119] In the second embodiment, the method for manufacturing the resonator includes the following steps:

[0120] - Provide ZT-cut quartz wafers, apply a first mask to the wafer surface to cover the first surface intended to form a frame 202 with a C-shaped portion, and leave a portion of the wafer surface intended to form a thinner planar portion 199 of the wafer uncovered;

[0121] - The outline of the resonant plate 201 is cut out using a femtosecond laser or deep reactive ion etching (DRIE), and the tethers 206a and 206b extend from the resonant plate to the C-shaped part of the frame 202.

[0122] Figure 8c An embodiment of a resonator obtained by a manufacturing method according to the second embodiment is shown, wherein the method includes cutting by deep reactive ion etching (DRIE) or femtosecond laser. Figure 8aThe pre-formed resonator's planar portion 199 is used to form the resonant plate 201 and tethers 206a, 206b. The cutting of the planar portion 199 to form the resonant plate 201 and tethers 206a, 206b can be limited to following the contours of the resonant plate and tethers without removing the remaining planar portion 199b attached to the intermediate portion 216. A DRIE or femtosecond laser can cut a well-defined shape, and to ensure proper oscillation of the resonant plate, a gap 215 of at least about 1 μm, preferably at least about 5 μm, around the resonant plate 201 and tethers 206a, 206b is sufficient. Advantageously, the area of ​​the resulting resonant plate 201 is smaller than the initial area of ​​the planar portion 199 to ensure a constant thickness of the resonant plate 201 and minimize its defects.

[0123] In one aspect of the present invention, a method for manufacturing a resonator according to a third embodiment includes the following steps:

[0124] - We offer ZT-cut quartz wafers; and

[0125] - The outline of the resonant plate 201 is cut out using a femtosecond laser or deep reactive ion etching (DRIE), and the tethers 206a and 206b extend from the resonant plate to the C-shaped part of the frame 202.

[0126] Figure 9a A preformed resonator according to another embodiment is shown, wherein the preformed resonator includes a frame 202 and a planar portion 199a. The planar portion 199a may have the same thickness as the frame 202, or the planar portion 199a may be made thinner relative to the thickness of the frame 202 by a physical etching process (e.g., DRIE or femtosecond laser processing), such that the sidewalls of the frame are substantially perpendicular to the planar portion 199a. This technique does not leave etching residues and allows the contours of the resonant plate 201 and the tethers 206a, 206b to be cut out by DRIE or femtosecond laser, thereby leaving a small gap between the frame 202 and the components of the resonant plate 201 and the tethers 206a, 206b, but the ends of the tethers are attached to the frame 202. For the resonant plate to oscillate properly, it is sufficient to leave a gap 215 of at least about 1 μm, preferably at least about 5 μm, around the resonant plate 201 and the tethers 206a, 206b.

[0127] Any of the above manufacturing methods can include the step of forming a notch in the frame to obtain the mounting portion and the C-shaped portion.

[0128] In any of the above manufacturing methods, multiple resonators can be fabricated on the same wafer. Advantageously, when the multiple resonators are located on the same wafer, electrodes can be deposited on the resonator plate, and wiring and mounting pads can be deposited on the frame. The resonators on the same wafer can then be separated from each other, preferably by femtosecond laser or DRIE.

[0129] Frequency tuning can be achieved by depositing or removing mass, for example, through evaporation, sputtering, laser beam etching, or ion beam etching. Since the mass distribution on the resonant plate affects its thermal performance, fine-tuning of the frequency-temperature characteristics can be achieved through localized ablation or mass deposition. This can be considered higher-order frequency tuning. Tuning typically acts on the mass of the metal layer on the resonator, but in principle, it can also act directly on the quartz.

[0130] In a non-limiting example according to the invention, the resonator includes a resonant plate 201 and a frame 202. The frame 202 is adapted to a rectangular profile of 1400 μm x 580 μm and has a thickness of 127 μm. The resonant plate has a thickness of 50 μm, a width of 330 μm, a maximum length LR1 at the edge of the resonant plate of 570 μm, and a second length LR2 at the central longitudinal axis of 560 μm. The frame includes a C-shaped portion 203, which includes a first arm 204 and a second arm 205, and a first tether 206a and a second tether 206b connect the resonant plate 201 to the frame 202. The tethers 206a and 206b and the resonant plate 201 are all 50 μm thick. The tethers 206a and 206b are both 50 μm wide and 90 μm long. The resonant plate 201 includes a pair of first electrodes 208, 208' connected to the first mounting pad 210, and a pair of second electrodes 209, 209' connected to the second mounting pad 211, as described above. Figure 4a As described in the embodiments.

[0131] Mounting pads are arranged on the mounting section of the frame, which is connected to the C-shaped section via a stem. The stem is coplanar with the mounting section and the C-shaped section and forms a notch between them.

[0132] Figure 7A simulated image of a resonator according to an embodiment of the present invention is shown, wherein the geometry is optimized to minimize residual coupling with the tethers and frame. In the simulated image, darker areas represent the resonator plate 201 regions where the tensile deformation is most significant on both sides of the node plane 207. Brighter areas represent regions with minimal deformation. It can be seen that the vibration amplitude is at a minimum or zero in the region of the resonator plate 201 near the node plane and on the tethers 206a and 206b. Therefore, when the resonator is in use, i.e., when the resonator plate is subjected to an alternating electric field, the tethers 206a and 206b and the region of the resonator plate 201 near the node plane 207 remain stationary relative to the frame 202.

[0133] According to the present invention, the size of ZT-cut quartz resonators can be reduced by providing a resonant plate with a simpler shape, easier processing, and more stable fixation.

[0134] Figure Labels

[0135] 100 Existing Technology Resonators

[0136] 101 First Resonant Plate

[0137] 102 Second Resonant Plate

[0138] 103 resonant arms

[0139] 104 Installation Department

[0140] 105 cantilever

[0141] 199 planar portion of preformed resonator

[0142] 199b Remaining Plane Section

[0143] 200 resonators

[0144] 201 resonant plate

[0145] 202 Framework

[0146] 203 C-shaped part

[0147] 204 First Arm

[0148] 205 Second Arm

[0149] 206a / 206b ropes

[0150] 207 Node Plane

[0151] 208 First Electrode

[0152] 209 Second Electrode

[0153] 208' third electrode

[0154] 209' Fourth Electrode

[0155] 210 First mounting pad

[0156] 211 Second mounting pad

[0157] 212 Installation Department

[0158] 213 Notch

[0159] 214 piezoelectric layer

[0160] 215 Space between the frame and the resonant plate

[0161] 216 Etching Residue

[0162] TR resonator thickness

[0163] TF frame thickness

[0164] SR resonator surface

[0165] SR1 SR's first side

[0166] SR2 SR's second side

[0167] Maximum length of LR1 resonator

[0168] The second length of the LR2 resonator

[0169] WR resonator width

[0170] The center width of the WC resonator

Claims

1. A resonator (200), comprising: - A resonant plate (201) having a thickness TR and a surface SR, the surface SR having a maximum length LR1 and a width WR, wherein the resonant plate (201) is ZT-cut quartz; - A frame (202) comprising a C-shaped portion (203) including a first arm (204) and a second arm (205) extending at least partially around the width edge of the resonant plate, wherein each arm (204, 205) is connected to the resonant plate by means of a tether (206a, 206b).

2. The resonator according to claim 1, wherein, A node plane (207) is defined, which is orthogonal to the surface SR of the resonant plate (201) and passes through the central longitudinal axis of the resonant plate (201), wherein the tethers (206a, 206b) pass through the node plane (207).

3. The resonator according to claim 1 or 2, wherein, The resonant plate (201) is configured to oscillate on both sides of the node plane (207) along its width WR direction, and the C-shaped portion (203) of the frame (202) is spaced apart from the resonant plate (201) to prevent the resonant plate (201) from contacting the frame (202) when the resonant plate (201) oscillates.

4. The resonator according to any one of the preceding claims, wherein, The resonant plate (201) includes at least a first electrode (208) and a second electrode (209), which are spaced apart from each other and electrically connected to a first mounting pad (210) and a second mounting pad (211) arranged on the frame (202), respectively. The first electrode (208) and the second electrode (209) are arranged on the resonant plate (201) to generate an electric field between two opposing surfaces of the resonant plate located on both sides of the node plane (207).

5. The resonator according to any one of the preceding claims, wherein, The first electrode (208) and the second electrode (209) are arranged on the resonant plate (201) so that when the first electrode and the second electrode are connected to an alternating voltage to generate an alternating electric field between the two electrodes, the resonant plate deforms along the width of the resonant plate.

6. The resonator according to any one of the preceding claims, wherein, The tethers (206a, 206b) are integral with the resonant plate (201) and the frame (202). The first tether (206a) extends between the resonant plate (201) and the first arm (204) of the C-shaped portion (203), and the second tether (206b) extends between the resonant plate (201) and the second arm (205) of the C-shaped portion (203) of the frame (201).

7. The resonator according to any one of the preceding claims, wherein, The resonant plate (201) has a minimum length LR2, which extends between two locations near the following two: - A first corner formed between the first tether and the first lateral edge of the resonant plate; and - A second corner is formed between the second tether and the second lateral edge of the resonant plate.

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

9. The resonator according to any one of the preceding claims, wherein, The resonant plate (201) is substantially symmetrical about its central width axis MW and about its central longitudinal axis that coincides with the node plane (207).

10. The resonator according to any one of the preceding claims, wherein, The frame (202) has a frame thickness TF, and the resonator has a resonator thickness TR, the resonator thickness TR being between 25% and 100% of the frame thickness TF, preferably between 25% and 75%, more preferably between 25% and 50%, preferably, wherein the maximum thickness of the frame is less than or equal to 200 μm, preferably less than or equal to 150 μm, more preferably less than or equal to 120 μm.

11. The resonator according to any one of the preceding claims, wherein, The maximum length of the resonant plate (201) is less than or equal to 2500 μm, preferably less than or equal to 1000 μm, and more preferably less than or equal to 600 μm.

12. The resonator according to any one of the preceding claims, wherein, The resonant 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 any one of the preceding claims, wherein, The frame (202) includes a mounting portion (212) comprising a first mounting pad (210) and a second mounting pad (211). The mounting portion (212) extends substantially parallel to the first arm (204) and the second arm (205) of the C-shaped portion (203). The mounting portion (212) is connected to the C-shaped portion (203) and together with the C-shaped portion (203) forms a notch (213).

14. The resonator according to any one of the preceding claims, wherein, The rope is attached to: - The length is between 10 μm and 300 μm, preferably between 20 μm and 150 μm, and more preferably between 40 μm and 100 μm; and / or - The width is 25% or less of the width of the resonant plate; and / or - The thickness is 50% to 150% of the thickness of the resonant plate.

15. A method for manufacturing a ZT-cut resonator, wherein, The method includes the following steps: - We provide ZT-cut wafers; - A resonator shape layout is defined on the wafer, wherein the resonator shape layout includes a resonator frame shape layout, a resonator plate shape layout and a tether shape layout, wherein the tether shape layout is positioned along the central longitudinal axis of the resonator plate shape layout and connects the side of the resonator plate shape layout to the resonator frame shape layout. - A portion of the wafer is etched to obtain the outline of the resonant plate, which has tethers on both sides and the tethers remain integrated with the resonator frame; - Perform the following deposition operations: • Deposit at least two separate electrodes on the resonant plate, such that the main portion of the first electrode is arranged on one side of the plane passing through the tether, and the main portion of the second electrode is arranged on the other side of the plane passing through the tether; • Two mounting pads are deposited on the resonator frame layout; and • Deposition connects each electrode to the corresponding mounting pad via a trace; and - Etch the outline of the resonator frame layout to obtain the resonator.

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