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

(19) State Intellectual Property Office (12) Invention Patent Application (10) Application Publication Number (43) Application Publication Date (21) Application Number 202511289339.2 (22) Application Date 2025.09.10 (30) Priority Data 24200067.7 2024.09.12 EP (71) Applicant Microcrystal Ltd. Address Switzerland (72) Inventor S. Dalla Piazza F. Stob (74) Patent Agency Beijing Zhongzi Law Firm 11247 Patent Attorney Mi Fenghua Wu Peng (51) Int.Cl. H03B 5 / 06 (2006.01) H03B 5 / 32 (2006.01) H10N 30 / 082 (2023.01) (54) Title of Invention: ZT-Quartz Resonator (57) Abstract: One aspect of the present invention relates to a resonator comprising: - a resonant plate having a thickness and a surface having a maximum length and width, wherein the resonant plate is ZT-cut quartz; and - a frame comprising a C-shaped portion including a first arm and a second arm extending at least partially around a lateral edge of the resonant plate, wherein both the first arm and the second arm are connected to the resonant plate by means of a tether. Claims 2 pages, Description 10 pages, Drawings 10 pages, CN 121664112 A 2026.03.13 CN 1 21 66 41 12 A 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) including a C-shaped portion (203) including a first arm (204) and a second arm (205) extending at least partially around a 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, the node plane (207) being orthogonal to the surface SR of the resonant plate (201) and passing 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), the first electrode (208) and the second electrode (209) being spaced apart from each other and electrically connected to a first mounting pad (210) and a second mounting pad (211) respectively arranged on the frame (202), the first electrode (208) and the second electrode (209) being 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) 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 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 shortest length LR2 extending between two locations near: - a first corner formed between the first tether and a first lateral edge of the resonant plate; and - a second corner formed between the second tether and a 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, more preferably at least 98% of the maximum length LR1. 9. The resonator according to any of the preceding claims, wherein the resonant plate (201) is substantially symmetrical about its intermediate width axis MW and substantially symmetrical about its central longitudinal axis coinciding with the node plane (207). 10. The resonator according to any 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 shortest length LR2 is at least 90% of the maximum length LR1.The maximum thickness 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, 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), the mounting portion (212) including a first mounting pad (210) and a second mounting pad (211), the mounting portion (212) extending substantially parallel to a first arm (204) and a second arm (205) of the C-shaped portion (203), the mounting portion (212) being connected to the C-shaped portion (203) and forming a notch (213) together with the C-shaped portion (203). 14. The resonator according to any one of the preceding claims, wherein the tether has: - a length between 10 μm and 300 μm, preferably between 20 μm and 150 μm, more preferably between 40 μm and 100 μm; and / or - a width of 25% or less of the width of the resonant plate; and / or - a thickness of 50% to 150% of the thickness of the resonant plate. 15. A method for manufacturing a ZT-diced resonator, wherein the method comprises the following steps: - providing a ZT-diced wafer; - defining a resonator shape layout 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 a central longitudinal axis of the resonator plate shape layout and connects the sides of the resonator plate shape layout to the resonator frame shape layout; - etching a portion of the wafer to obtain a contour of a resonator plate, wherein tethers are attached to both sides of the resonator plate and the tethers remain integral with the resonator frame; - performing the following deposition operations: · depositing at least two separate electrodes on the resonator plate, such that the main portion of a first electrode is disposed on one side of a plane passing through the tethers, and the main portion of a second electrode is disposed on the other side of a plane passing through the tethers; · depositing two mounting pads on the resonator frame layout; and · depositing connection traces connecting each electrode to a corresponding mounting pad; and - etching the contour of the resonator frame layout to obtain the resonator. Claims 2 / 2, page 3 CN 121664112 A ZT-quartz resonator technical field

[0001] This invention relates to a miniature quartz resonator, which is manufactured from ZT-cut quartz by (machine) processing and configured to oscillate in a length-extending profile mode along one edge of a resonant plate. Background Art

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

[0003] The cutting angle of the ZT-resonator is chosen to obtain a near-zero first-order frequency-temperature coefficient, and the connection with the surface shear mode and the extension mode along the other edge of the resonant plate is negligible. Different ZT cuts with similar characteristics can be obtained by first rotating an angle ψ about the Z-axis, then rotating an angle φ about the X'-axis, and then rotating an angle θ about the Z'-axis perpendicular to the plane of the resonant plate. A common cut is ψ = 90°, so the second rotation would be an angle φ = 26.5° about X' = Y, and an angle θ = 20° about Z'. This cut is called ZTY. The simplest cut in the ZT series is likely a simple rotation around X by φ = 24°, referred to as 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. Thus, a third-order frequency-temperature characteristic is obtained. The third-order temperature coefficient is about twice as small as that of the AT-cut resonator. Furthermore, for a given frequency, the ZT can be made much smaller than the AT.

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

[0006] Since the contour modes are very sensitive to impacts acting on their periphery, the manufacturing process must ensure precise control of the shape. In addition, anchoring must also be done with extra care. The anchoring device holds the resonator in place while ensuring good decoupling from the package in order to maintain the high quality factor and excellent thermal performance of the ZT-resonator.

[0007] Previous anchoring was achieved using a resonant arm, which minimizes mode interference (Figure 1). However, the geometry of the anchoring device is also very critical.

[0008] Figure 1 shows an example of a prior art ZT-cut quartz resonator 100, which includes 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 by 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. One side of each resonant plate has a first electrode (not shown), and the opposite side of each resonant plate has a second electrode (not shown), 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 arrow. 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. Due to the two resonantsThe plates are connected by resonant arms. The length 106 of the resonator is relatively long, for example, 3850 μm, while the width 107 of the resonant plate is also relatively long, for example, 2024 μm.

[0009] ZT-cut quartz resonators need to be miniaturized; however, the design of such resonators is complex and difficult to process in a smaller size, which limits their miniaturization. In addition, the resonant arms and support arms must be wide enough to withstand the mechanical constraints imposed by the bulky resonant plates. The symmetry of the resonant structure must be well controlled to minimize energy loss at the mounting and thus reduce attenuation. Specification 1 / 10 pages 4 CN 121664112 A 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 the miniaturization of such resonators.

[0011] According to a first aspect, the resonator comprises:

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

[0013] - a frame including a C-shaped portion comprising a first arm and a second arm extending at least partially around a lateral edge of the 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 orthogonal to the surface of the resonant plate and passing through the central longitudinal axis of the resonant plate, wherein the tether passes through the nodal plane.

[0015] Preferably, the resonant plate is configured to oscillate on both sides of the nodal plane along its width direction, and the C-shaped portion of the frame is spaced apart from the resonant plate to prevent contact between the resonant plate and the frame during oscillation of the resonant plate and to ensure 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 the frame. 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.

[0017] Preferably, a first electrode and a 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, a first tether extends from a first side of the resonant plate to a first arm of the C-shaped portion of the frame, and a second tether extends from a second side of the resonant plate to a second arm of the C-shaped portion of the frame.

[0019] Preferably, these tethers are integral 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 a position close to the longitudinal edge on both sides of the node plane.

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

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

[0023] - a second corner 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 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, 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, preferably 2000 μm or less, 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, preferably between 20 μm and 150 μm, and 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) / (maximum length) is between 0.4 and 0.8, preferably between 0.5 and 0.7.

[0034] Preferably, the frame includes a mounting portion, the mounting portion including 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, preferably less than or equal to 2500 μm, 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, preferably less than or equal to 150 μm, 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] - providing a ZT-cut wafer;

[0039] - Define a resonator shape layout 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 surfaces of the resonator plate shape layout to the resonator frame shape layout;

[0040] - Etch a portion of the wafer to obtain the outline of the resonator plate, the resonator plate having tethers on both sides, and the tethers remaining integral with the resonator frame;

[0041] - Perform the following deposition operations:

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

[0043] • Deposit two mounting pads on the resonator frame layout; and

[0044] • Deposit connection traces connecting each electrode to the corresponding mounting pad; 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] - applying a first mask to the surface of a wafer to cover a first surface intended to form a frame having a C-shape, leaving a portion of the wafer surface intended to form a thinner planar portion of the wafer uncovered;

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

[0049] - applying a second mask 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-shape of the frame; and

[0050] - performing a chemical wet etching on the remaining uncovered surface of the wafer to form the outline of the resonant plate and the tether.

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

[0052] - Applying a first mask to the surface of a wafer to cover a first surface intended to form a frame having a C-shape, leaving a portion of the wafer surface intended to form a thinner planar portion of the wafer uncovered; Specification 3 / 10 page 6 CN 121664112 A

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

[0054] - Cutting out the contour of the resonant plate using a femtosecond laser or deep reactive ion etching (DRIE), wherein tethers extend from the resonant plate to the C-shape of the frame.

[0055] In an alternative embodiment, the step of cutting by femtosecond laser or deep reactive ion etching (DRIE) to etch a portion of the wafer to obtain the contour of the resonant plate is performed, with tethers on both sides of the resonant plate, and the tethers remain integral with the resonator frame. Brief Description of the Drawings

[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] FIG1 shows an embodiment of a resonator according to the prior art;

[0058] FIG2 shows a top view of an embodiment of a resonator according to the invention;

[0059] FIG3 shows a side view of an embodiment of a resonator according to the invention;

[0060] FIGS. 4a to 4f show various schematic cross-sectional views along the width direction of resonant plates with different electrode arrangements;

[0061] FIG5 shows a schematic cross-sectional view along the width direction of a resonant plate having piezoelectric components;

[0062] FIGS. 6a to 6d show schematic top views of resonant plates according to various embodiments of the invention;

[0063] FIG7 shows a simulated image of a resonator according to an embodiment of the invention deforming under an alternating electric field;

[0064] FIG. 8a shows a top view of an embodiment of a preformed resonator, FIG. 8b shows a top view of an embodiment of a resonator obtained by a manufacturing method according to a first embodiment of the manufacturing method, and FIG. 8c shows a top view of another embodiment of a resonator obtained by a manufacturing method according to a second embodiment of the manufacturing method;

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

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

[0067] The present invention will now be described in more detail with reference to Figures 2 and 3, which illustrate an embodiment of a resonator 200, the resonator 200 comprising:

[0068] - a resonant plate 201 having a thickness TR and a surface SR, the surface SR having lateral edges and longitudinal edges, a maximum length LR1 and a width WR, wherein the resonant plate 201 is ZT-cut quartz;

[0069] - a frame 202 including a C-shaped portion 203 including 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 tethers are also made of quartz. For ease of manufacture, the entire resonator 200 is integrally formed from a ZT-cut quartz wafer. Each wafer can accommodate a certain number of resonators. The shape of the resonator 200 can be obtained, for example, by chemical wet etching or deep reactive ion etching, or as described in document WO2013 / 092920.The method described above can be used to obtain the material, or by femtosecond laser-induced chemical etching as described in the specification 4 / 10 pages of 7 CN 121664112 A in Microsystems & Nanoengineering (2023) 9:38 by Linden et al.

[0071] When the term “surface” is used with respect to the resonant plate, it refers to the largest surface of the resonant plate located on both sides of the resonant plate, unless otherwise stated.

[0072] The term “C-shaped portion” refers to the C-shaped portion of the frame, wherein the portion preferably includes a sub-portion 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-portion, the first arm, and the second arm are preferably straight. Preferably, the sub-portion 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 tethers 206a, 206b pass through the node plane 207. The node plane 207 is a virtual plane orthogonal to the resonant plate. When the resonant plate oscillates under the influence of an alternating electric field, the vibration amplitude is minimal or zero in this virtual plane.

[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, preferably 10 μm, 20 μm, 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 separated from each other and electrically connected to a first mounting pad 210 and a second mounting pad 211 arranged 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 either side of the node plane.

[0077] The first electrode 208 and the second electrode 209 are arranged on the 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 direction. The electrode configuration can be optimized to maximize piezoelectric coupling with the resonant mode while suppressing unwanted modes.

[0078] Figures 4a to 4f show various possible configurations of the electrodes on the resonant plate 201. In Figure 4a, the first electrode 208 is positioned...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] In FIG4b, 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] In FIG4c, a pair of first electrodes 208, 208' are located on both sides of the resonant plate 201 and partially cover the surface of the resonant plate on the first side of the node plane 207; a pair of second electrodes 209, 209' are located on both sides of the resonant plate 201 and partially cover 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] In FIG. 4d, 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, and partially covers 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 and completely covers the surface of the resonant plate on the second side of the node plane 207, and partially covers 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] In FIG. 4e, the first electrode 208 extends from one side of the resonant plate (page 5 / 10, CN 121664112 A) to the other side of the resonant plate via a groove in the resonant plate 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 via a corresponding groove in the resonant plate on the other side of the node plane 207. The first electrode 208 and the second electrode 209 are spaced apart from each other and have opposite polarities.

[0083] In FIG. 4f, 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 an optional embodiment shown in FIG5, 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 connected to a first mounting pad 210, and the second electrode 209” is connected to a second mounting pad 211 with opposite polarity.

[0086] As shown in FIG3, tethers 206a and 206b are arranged on both sides of the resonant plate 201. The first tether 206a extends from the first arm 204. Extending to the resonant plate 201, a 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 tether 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 tether is preferably 25% or less of the width of the resonant plate. The thickness of the tether 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 by 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 coupling between the resonator and its external components (frame, package), the thickness of the resonant 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 smaller.=50μm or equal to.

[0091] The thickness of the tethers 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 tethers 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 moving mass relative to the frame 202 is reduced, thereby reducing the residual motion transmission (tactile effect) from the resonant plate 201 to the frame 202; Specification 6 / 10 pages 9 CN 121664112 A

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

[0096] Although the 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 such that it has a second length LR2 shorter than its maximum length LR1, which extends between two locations near:

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

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

[0099] In the context of this application, the term "near" refers to a distance of at most 25% of the longest distance between the tether and the lateral edge of the resonant plate.

[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 intermediate width axis MW and central longitudinal axis (or node plane 207). “Substantially symmetrical” should be understood as: small deviations relative to perfect geometric symmetry may be required to compensate for minor asymmetric residues formed by etching residues generated in anisotropic etching and chemical wet etching processes.

[0102] The maximum length LR1 of the resonant plate is advantageously located at or near the longitudinal edge of the resonant plate, for example, at a distance less than 10% of the width of the resonant plate. In this context, “at a distance near 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 show examples of embodiments of a resonant plate with tethers. In Figure 6a, the corners of the resonant plate and the corners between the lateral edges and the tethers are sharp angles. In Figure 6b, the corners between the longitudinal edge and the lateral edge are sharp angles.The portion is chamfered. In Figure 6c, the corners between the tether and the lateral edge may contain etching residue, so the shortest length LR2 of the resonant plate is slightly off-center from the tether, but still located near the tether.

[0104] Figure 6d shows an alternative embodiment of the resonant plate with tether, wherein the lateral edge of the resonant plate forms a notch between the portion of the resonant plate with the maximum length LR1 and the tether 206a, 206b, thereby forming a second portion with 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%, preferably between 25% and 60%, 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, 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] The 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 the mounting portion 212 is connected to the C-shaped portion 203 and forms a notch 213 with the C-shaped portion 203, as shown in FIG2. Optionally, the mounting portion is located on the C-shaped portion. For example, the first mounting pad may be mounted on the first arm and opposite to the first tether, and the second mounting pad may be mounted on the second arm and opposite to the second tether. In another embodiment, the first mounting pad and the second mounting pad may be mounted on the frame portion connecting the first arm and the second arm.

[0109] The maximum length of the 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. Specification 7 / 10 pages 10 CN 121664112 A

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

[0111] The resonant plate 201, the frame 202, and the tethers 206a, 206b can be obtained using photolithography 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 a first embodiment includes the following steps:

[0113] - providing a ZT-cut quartz wafer, applying a first mask to the surface of the wafer to cover a first surface intended to form a frame 202 having a C-shape, leaving a portion of the wafer surface intended to form a thinner planar portion 199 of the wafer uncovered;

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

[0115] - applying a second mask 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-shape of the frame 202; and

[0116] - performing a chemical wet etching on the remaining uncovered surface of the wafer to form the outline of the resonant plate and the tether.

[0117] FIG8a shows a pre-formed resonator obtained by chemical wet etching. 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 with gradually varying thickness located between the frame 202 and the planar portion 199.

[0118] FIG8b shows an embodiment of a resonator obtained by a manufacturing method according to the first embodiment, wherein the method includes the step of chemically wet etching the planar portion 199 of the preformed resonator described above in conjunction with FIG8a to form a resonant plate 201 and tethers 206a, 206b. In order to obtain a shape with clear boundaries, it is necessary to form a minimum gap 215 with a width between the resonant plate 201 and the intermediate portion 216. For example, the width of the minimum gap is greater than 20 μm, preferably at least 50 μm, and more preferably at least 75 μm. Advantageously, the area of ​​the resonant plate 201 thus obtained is smaller than the initial area of ​​the planar portion 199 in order to ensure that the thickness of the resonant plate 201 is constant and to minimize its defects.

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

[0120] - providing a ZT-cut quartz wafer, applying a first mask to the wafer surface to cover a first surface intended to form a frame 202 having a C-shape, leaving a portion of the wafer surface intended to form a thinner planar portion 199 of the wafer uncovered;

[0121] - cutting out the outline of a resonator plate 201 using a femtosecond laser or deep reactive ion etching (DRIE), and tethers 206a, 206b extending from the resonator plate to the C-shape of the frame 202.

[0122] FIG8c shows an embodiment of a resonator obtained by the manufacturing method according to the second embodiment, wherein the method includes cutting the planar portion of the pre-formed resonator of FIG8a by deep reactive ion etching (DRIE) or a femtosecond laser.199 is used to form the resonant plate 201 and tethers 206a, 206b. The cutting of the planar portion 199 for forming 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, 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 tethers 206a, 206b. 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. Specification 8 / 10 pages 11 CN 121664112 A

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

[0124] - providing a ZT-cut quartz wafer; and

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

[0126] FIG9a shows a preformed resonator according to another embodiment, 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 form etching residues and the contours of the resonant plate 201 and tethers 206a, 206b can be cut using DRIE or femtosecond laser, thereby leaving a small gap between the frame 202 and the components of the resonant plate 201 and tethers 206a, 206b, but the ends of the tethers are attached to the frame 202. For the resonant plate to oscillate properly, 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.

[0127] Any of the above manufacturing methods may include the step of forming notches in the frame to obtain mounting portions and C-shaped portions.

[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 resonant 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 deposition or removal of mass, for example by means of evaporation, sputtering, laser beams or ion beams.Etching. Since the mass distribution on the resonant plate affects its thermal performance, the frequency-temperature characteristics can be fine-tuned by local ablation or mass deposition. This can be considered as high-order frequency tuning. Tuning usually 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 thickness of the tethers 206a, 206b and the resonant plate 201 is 50 μm. The width of the tethers 206a and 206b is 50 μm and the length is 90 μm. 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 with respect to the embodiment of FIG4a.

[0131] The mounting pad is arranged on the mounting portion of the frame, which is connected to the C-shaped portion by a stem, the stem being coplanar with the mounting portion and the C-shaped portion and forming a notch between them.

[0132] FIG7 shows a simulation image of a resonator according to an embodiment of the present invention, wherein the geometry is optimized to minimize residual coupling with the tethers and the frame. In the simulation image, the darker areas represent the resonant plate regions on both sides of the node plane 207 where the tensile deformation of the resonant plate 201 is most significant. The brighter areas represent the regions with the least deformation. It can be seen that the vibration amplitude is at its minimum or zero in the region near the node plane of the resonant plate 201 and on the tethering ropes 206a and 206b. Therefore, when the resonator is in use, that is, when the resonant plate is subjected to an alternating electric field, the tethering ropes 206a and 206b and the region near the node plane 207 of the resonant plate 201 remain stationary relative to the frame 202.

[0133] According to the present invention, by providing a resonant plate with a simpler shape, easier processing, and more stable fixation, the size of the ZT-cut quartz resonator can be reduced. Specification 9 / 10 pages 12 CN 121664112 A

[0134] Reference numerals

[0135] 100 Prior art resonator

[0136] 101 First resonant plate

[0137] 102 Second resonant plate

[0138] 103 Resonant arm

[0139] 104 Mounting part

[0140] 105 Cantilever

[0141] 199 Planar portion of preformed resonator

[0142] 199b Remaining planar portion

[0143] 200 Resonator

[0144] 201 Resonant plate

[0145] 202 Frame

[0146] 203 C-shaped portion

[0147] 204 First arm

[0148] 205 Second arm

[0149] 206a / 206b Tie rope

[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 Mounting part

[0158] 213 Notch

[0159] 214 Piezoelectric layer

[0160] 215 Space between frame and resonant plate

[0161] 216 Etching residue

[0162] TR Resonator thickness

[0163] TF Frame thickness

[0164] SR Resonator surface

[0165] SR1 First side of SR

[0166] SR2 Second side of SR

[0167] LR1 Maximum length of resonator

[0168] LR2 Second length of resonator

[0169] WR Width of resonator

[0170] WC Center width of resonator Specification 10 / 10 page 13 CN 121664112 A Figure 1 Specification Figure 1 / 10 page 14 CN 121664112 A Figure 2 Figure 3 Specification Figure 2 / 10 page 15 CN 121664112 A Figure 4a Figure 4b Figure 4c Specification Figure 3 / 10 page 16 CN 121664112 A Figure 4d Figure 4e Figure 4f Appendix 4 / 10 Page 17 CN 121664112 A Figure 5 Figure 6a Figure 6b Appendix 5 / 10 Page 18 CN 121664112 A Figure 6c Figure 6d Appendix 6 / 10 Page 19 CN 121664112 A Figure 7 Appendix 7 / 10 Page 20 CN 121664112 A Figure 8a Figure 8b Appendix 8 / 10 Page 21 CN 121664112 A Figure 8c Figure 9a Appendix 9 / 10 Page 22 CN 121664112 A Figure 9b Appendix 10 / 10 Page 23 CN 121664112 A Abstract One aspect of the inventionrelates to a resonator comprising: - a resonant plate having a thickness and a surface having a maximum length and width, wherein the resonant plate is ZT- cut quartz; and - a frame comprising a C-shaped portion including a first arm and a second arm extending at least partially around a lateral edge of the resonant plate, wherein both the first arm and the second arm are connected to the resonant plate by means of a tether.

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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