AT quartz crystal oscillator vibration part structure, preparation method and quartz crystal oscillator

Abstract

The invention relates to an AT quartz crystal oscillator vibration part structure, a preparation method and a quartz crystal oscillator in the field of quartz crystal components, and the structure comprises a quartz wafer which is provided with a first groove and a second groove along the upper and lower surfaces of the quartz wafer in the thickness direction; the first boss and the bottom of the first groove are integrally formed, the second boss and the bottom of the second groove are integrally formed, and at least partial projections of the first boss and the second boss in the axial direction in the thickness direction of the quartz wafer coincide; the first electrode covers the top surface of the first boss; and the second electrode covers the top surface of the second boss. According to the AT quartz crystal oscillator vibration piece, through the structural optimization design, the energy loss during device vibration can be reduced, the natural quality factor Q value can be improved, the distribution of vibration energy can be better controlled, the frequency stability can be improved, and the precision, the resolution ratio and the sensitivity of the device can be improved.

Description

Technical Field

[0001] This application relates to the field of quartz crystal components, and particularly to a vibration element structure of an AT quartz crystal oscillator, a preparation method thereof, and a quartz crystal oscillator. Background Art

[0002] Quartz crystal products such as AT quartz crystal oscillators have experienced rapid development, and the market demand for quartz crystal oscillators continues to grow. The main driving factors include the applications of emerging technologies such as 5G, Internet of Things (IoT), Bluetooth 5.0, and Wi-Fi 6. The applications of these technologies have promoted the wide application of quartz crystal oscillators in fields such as communication equipment, mobile terminals, automotive electronics, and smart homes, further driving the market demand. A quartz crystal oscillator, that is, a quartz crystal resonator, mainly consists of a quartz wafer, electrodes, a bracket, and a housing. However, the current structure of the vibration element of a quartz crystal oscillator formed by the electrode and the mesa (vibration platform) part of the quartz wafer has problems such as poor control ability of vibration energy distribution and poor frequency stability, thus affecting the overall performance and reliability of the quartz crystal oscillator. Summary of the Invention

[0003] In view of the problems existing in the background art, this application provides a vibration element structure of an AT quartz crystal oscillator, a preparation method thereof, and a quartz crystal oscillator, which can improve the quality factor, enhance the frequency stability, and improve the accuracy, resolution, and sensitivity of the device.

[0004] According to the first aspect of the present invention, there is provided a vibration element structure of an AT quartz crystal oscillator, including: a rectangular quartz wafer, wherein first and second grooves are respectively provided on the upper and lower surfaces of the quartz wafer along its thickness direction; a first boss and a second boss, the first boss being integrally formed at the bottom of the first groove, and the second boss being integrally formed at the bottom of the second groove; a first electrode and a second electrode, the first electrode covering the top surface of the first boss, and the second electrode covering the top surface of the second boss.

[0005] By using the vibration element structure of an AT quartz crystal oscillator in this technical solution, the mesa (vibration platform) part of the vibration element structure of the AT quartz crystal oscillator is designed as a groove structure, that is, the first and second grooves, and at the same time, boss structures, that is, the first and second bosses, are respectively introduced into the central regions of the first and second grooves. This design of introducing a boss structure inside the groove, the combined structure of the groove and the boss can reduce the energy loss during the vibration of the device, improve the natural quality factor Q value, better control the distribution of vibration energy, enhance the frequency stability, and improve the accuracy, resolution, and sensitivity of the device.

[0006] In some embodiments of the present invention, the first groove and the second groove are both circular grooves that penetrate into the quartz wafer. The first boss and the second boss are respectively located at the bottom of the circular grooves, and both the first boss and the second boss are cylindrical in shape.

[0007] In some embodiments of the present invention, between the edges of the circular grooves on the upper and lower surfaces of the quartz wafer in the thickness direction and the first boss or the second boss in the circular groove is an annular groove with a certain width. The top surfaces of the first boss and the second boss are respectively higher than the bottom of the annular groove, showing a certain height difference, and the top surfaces of the first boss and the second boss are respectively lower than the corresponding outer surfaces of the quartz wafer.

[0008] In some embodiments of the present invention, at least a partial projection of the first boss and the second boss coincides axially in the thickness direction of the quartz wafer.

[0009] In some embodiments of the present invention, the axial projections of the first groove and the second groove in the thickness direction of the quartz wafer completely coincide.

[0010] In some embodiments of the present invention, the first electrode and the second electrode respectively include a Cr layer and an Au layer. The Cr layer is in contact with and adheres to the top surface of the first boss or the second boss, and the Au layer is in contact with and adheres to the Cr layer.

[0011] In some embodiments of the present invention, the thicknesses of the first boss and the second boss are respectively independently 1 μm to 2 μm.

[0012] In some embodiments of the present invention, the depths of the first groove and the second groove are respectively independently 2 μm to 4 μm.

[0013] In some embodiments of the present invention, the widths of the annular groove between the first boss and the first groove and the annular groove between the second boss and the second groove are respectively independently 15 μm to 20 μm.

[0014] In some embodiments of the present invention, the thickness of the quartz wafer is 20 μm to 25 μm.

[0015] According to a second aspect of the present invention, there is provided a method for preparing the above-mentioned AT quartz crystal oscillator vibrating element structure, comprising the following steps: preparing a rectangular quartz wafer; processing and forming a first transition groove and a second transition groove on the upper and lower surfaces of the quartz wafer along its thickness direction through photolithography and etching processes; forming an annular groove and a cylindrical first boss on the bottom of the first transition groove through film coating, photolithography and etching processes, and forming an annular groove and a cylindrical second boss on the bottom of the second transition groove by using the same processes, with the side walls of the first transition groove and the second transition groove being smoothly transitioned to the outer side walls of the corresponding annular grooves; then forming a first electrode on the top surface of the first boss and a second electrode on the top surface of the second boss by using a deposition process, both the first electrode and the second electrode being two layers, with the upper layer close to the quartz wafer being a Cr layer and the lower layer far from the quartz wafer being an Au layer; finally forming the AT quartz crystal oscillator vibrating element structure.

[0016] According to a third aspect of the present invention, there is provided a quartz crystal oscillator, comprising the above-mentioned AT quartz crystal oscillator vibrating element structure or the AT quartz crystal oscillator vibrating element structure prepared by the above-mentioned preparation method.

[0017] Compared with the prior art, the structure of the AT quartz crystal oscillator vibrating element of the present application is optimized in design, reducing the energy loss during device vibration, increasing the natural quality factor Q value, better controlling the distribution of vibration energy, improving the frequency stability, and enhancing the accuracy, resolution and sensitivity of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of illustrating the preferred embodiments and are not considered to be a limitation of the present application. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0019] Figure 1 is a schematic diagram of the overall structure of the AT quartz crystal oscillator vibrating element structure of the present invention;

[0020] Figure 2 is a schematic diagram of the structure showing the vibrating part of the present invention.

[0021] The reference numerals in the drawings are represented as follows: 1, quartz wafer; 2, first boss; 3, second boss; 4, first electrode; 5, second electrode; 6, first groove; 7, second groove; 8, Cr layer; 9, Au layer. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0022] It should be clear that the described embodiments are only a part of the embodiments of the present application, rather than all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments in the present application without creative efforts belong to the scope of protection of the present application.

[0023] When the following description refers to the accompanying drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. On the contrary, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0024] In the description of the present application, it should be understood that the terms "first", "second", etc. are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances. In addition, in the description of the present application, unless otherwise specified, "a plurality" means two or more. "And / or" describes the association relationship of associated objects and indicates that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. The character " / " generally represents an "or" relationship between the associated objects before and after.

[0025] The first aspect of the present invention provides a structure of an AT quartz crystal oscillator vibrating element. As Figure 1 and Figure 2 shown, the structure of the AT quartz crystal oscillator vibrating element includes a quartz wafer 1, a first boss 2, a second boss 3, a first electrode 4, and a second electrode 5. First grooves 6 and second grooves 7 are respectively provided on both surfaces of the quartz wafer 1 along its thickness direction.

[0026] Among them, the first boss 2 is integrally formed at the bottom of the first groove 6, and the second boss 3 is integrally formed at the bottom of the second groove 7; the first electrode 4 covers the top surface of the first boss 2, and the second electrode 5 covers the top surface of the second boss 3.

[0027] By using the structure of the AT quartz crystal oscillator vibrating element in this technical solution, the mesa (vibration platform) part of the AT quartz crystal oscillator vibrating element structure is designed as a groove structure, that is, the first groove 6 and the second groove 7, and at the same time, boss structures, that is, the first boss 2 and the second boss 3, are respectively introduced into the central regions of the first groove 6 and the second groove 7. The groove structure cooperates with the boss structure, which can reduce the energy loss during device vibration, improve the natural quality factor Q value, better control the distribution of vibration energy, enhance the frequency stability, and improve the accuracy, resolution, and sensitivity of the device.

[0028] In some embodiments of the present invention, as Figure 1 andFigure 2 As shown, the first groove 6 and the second groove 7 are both circular grooves that penetrate into the quartz wafer 1. The first boss 2 and the second boss 3 are respectively located at the bottom of the circular grooves, and both the first boss 2 and the second boss 3 are cylindrical protrusions.

[0029] In this embodiment, the first groove 6 and the second groove 7 are circular grooves. Cooperating with the cylindrical first boss 2 and second boss 3 can further reduce the energy loss during device vibration, improve the natural quality factor Q value, better control the distribution of vibration energy, enhance the frequency stability, and thus improve the accuracy, resolution, and sensitivity of the device.

[0030] In some other embodiments of the present invention, the first groove 6 and the second groove 7 can also be rectangular grooves, and the first boss 2 and the second boss 3 can also be rectangular protrusions, etc.; preferably, circular grooves and cylindrical protrusions are used.

[0031] In some embodiments of the present invention, the axial projections of the first groove 6 and the second groove 7 in the thickness direction of the quartz wafer 1 completely coincide.

[0032] In some embodiments of the present invention, as Figure 2 shown, the axial projections of the first boss 2 and the second boss 3 in the thickness direction of the quartz wafer 1 at least partially coincide. Further, the axial projections of the first boss 2 and the second boss 3 in the thickness direction of the quartz wafer 1 completely coincide.

[0033] By designing the complete coincidence of the first boss 2 and the second boss 3, that is, the complete coincidence of the first electrode 4 and the second electrode 5, it can be ensured that the excitation of the two electrodes on the crystal is more consistent, which helps to further improve the consistency and stability of the resonant frequency, and can reduce the parasitic capacitance between the electrodes, thereby improving the quality factor (Q value) of the crystal.

[0034] In some embodiments of the present invention, there are annular grooves with a certain width between the edges of the circular grooves on the upper and lower surfaces of the quartz wafer 1 in the thickness direction and the first boss 2 or the second boss 3 in the circular grooves. The top surfaces of the first boss 2 and the second boss 3 are respectively higher than the bottom of the annular grooves, showing a certain height difference, and the top surfaces of the first boss 2 and the second boss 3 are respectively lower than the corresponding outer surfaces of the quartz wafer 1.

[0035] The thicknesses of the first boss 2 and the second boss 3 are respectively independently 1 μm to 2 μm.

[0036] Further, the depths of the first groove 6 and the second groove 7 are respectively independently 2 μm to 4 μm.

[0037] In some embodiments of the present invention, the widths of the annular gaps between the first boss 2 and the first groove 6 and between the second boss 3 and the second groove 7 are independently 15 μm to 20 μm respectively.

[0038] In some embodiments of the present invention, the thickness of the quartz wafer 1 is 20 μm to 25 μm.

[0039] Further, the quartz wafer 1 may have a rectangular outer shape, with an outer length of 750 μm to 800 μm and a width of 500 μm to 550 μm.

[0040] In some embodiments of the present invention, as Figure 2 shown, both the first electrode 4 and the second electrode 5 are composite electrode layers of a Cr layer 8 and an Au layer 9, and the Cr layer 8 is the layer closer to the quartz wafer, that is, the Cr layer 8 contacts and adheres to the top surface of the first boss 2 or the second boss 3, and the Au layer 9 contacts and adheres to the Cr layer 8.

[0041] Further, the thickness of the Cr layer 8 is 3 nm to 5 nm, and the thickness of the Au layer 9 is 130 nm to 150 nm.

[0042] In some embodiments of the present invention, the diameters of the first electrode 4 and the second electrode 5 are 340 μm to 360 μm.

[0043] The second aspect of the present invention provides a preparation method for preparing the above-mentioned AT quartz crystal oscillator vibrating element structure, and the preparation method includes the following steps:

[0044] 1) Prepare a wafer substrate.

[0045] In some embodiments of the present invention, the wafer substrate may first use AT-cut natural or synthetic quartz crystal (SiO), then cut out the wafer with a diamond wire saw, and then obtain a rectangular quartz wafer through a grinding and polishing process.

[0046] 2) Process and form a first transition groove and a second transition groove on the upper and lower surfaces of the quartz wafer along its thickness direction through photolithography and etching processes;

[0047] In some embodiments of the present invention, including but not limited to, forming the first transition groove and the second transition groove through photolithography masks and dry etching processes, that is, initially forming the grooves in the vibrating element.

[0048] Further, a double-sided mask alignment technique can be used to align the first transition groove and the second transition groove.

[0049] 3) An annular groove and a cylindrical first boss are formed at the bottom of the first transition groove through coating, photolithography, and etching processes. An annular groove and a cylindrical second boss are formed at the bottom of the second transition groove using the same process. The side walls of the first transition groove and the second transition groove are smoothly transitioned with the outer side walls of the corresponding annular grooves respectively.

[0050] In some embodiments of the present invention, including but not limited to, continue to form the annular groove through photolithographic mask and dry etching processes, so that the remaining parts at the bottoms of the first transition groove and the second transition groove form a first boss structure and a second boss structure.

[0051] Further, a double-sided mask alignment technique can be used to align the two annular grooves, so that the first boss structure and the second boss structure are aligned.

[0052] 4) Then, a deposition process is used to form a first electrode on the top surface of the circular boss in the first transition groove and a second electrode on the top surface of the circular boss in the second transition groove. Both the first electrode and the second electrode are two layers, with a Cr layer on the upper layer and an Au layer on the lower layer.

[0053] In some embodiments of the present invention, including but not limited to, form electrodes on the bosses of the grooves through cleaning, yellow light process, and sputtering coating.

[0054] 5) An AT quartz crystal oscillator vibrating element structure is obtained.

[0055] The third aspect of the present invention provides a quartz crystal oscillator, which includes the above-mentioned AT quartz crystal oscillator vibrating element structure or the AT quartz crystal oscillator vibrating element structure prepared by the above-mentioned preparation method. It also includes a packaging structure, an oscillation circuit, etc. The AT quartz crystal oscillator vibrating element structure is encapsulated in the packaging structure to protect the AT quartz crystal oscillator vibrating element structure and provide a stable mechanical and electrical environment. The oscillation circuit is arranged in the packaging structure to control and adjust the vibration frequency of the AT quartz crystal oscillator vibrating element structure to ensure a stable output signal.

[0056] Next, the preparation method of the AT quartz crystal oscillator vibrating element structure in the present invention will be further described with specific embodiments.

[0057] Example 1

[0058] 1. Prepare a quartz wafer: The outer shape is rectangular, the quartz thickness is 20μm, the outer length is 750μm, and the width is 500μm.

[0059] 2. Machining of the transition groove: Transition grooves with a depth of 1μm along the wafer thickness direction are respectively formed in the central regions of the upper and lower surfaces of the quartz wafer through photolithography and etching. The diameter of the transition groove is 400μm.

[0060] 3. Formation of annular grooves and bosses: By means of photolithography, coating, and etching processes, annular grooves are respectively formed on the upper and lower surfaces in the thickness direction of the quartz wafer along the edge of the transition groove at the bottom of the transition groove. The width of the annular groove is 20 μm, and the depth of the annular groove is 1 μm. A cylindrical boss integrally connected with the quartz wafer is formed in the annular middle area at the bottom of the transition groove. The axial projections of the first boss and the second boss in the thickness direction of the quartz wafer completely coincide. The height difference between the bottom surface of the annular groove on the quartz and the cylindrical first boss is 1 μm. The height difference between the bottom surface of the annular groove on the quartz and the cylindrical second boss is 1 μm. The height difference between the top surface of the cylindrical first boss and the upper surface of the quartz wafer is 1 μm. The height difference between the top surface of the cylindrical second boss and the lower surface of the quartz wafer is 1 μm.

[0061] 4. Electrode preparation: Electrodes are respectively formed on the top surfaces of the upper and lower two cylindrical bosses by means of photolithography and coating processes. The electrodes cover the cylindrical bosses. The electrodes on the surface of the bosses are divided into two layers, mainly the Cr layer and the Au layer. The Cr layer contacts and adheres to the top surface of the boss, and the Au layer contacts and adheres to the Cr layer. The upper and lower two electrodes have the same thickness and the same diameter. The thickness of Cr in the electrode is 5 nm, the thickness of Au is 130 nm, and the diameter of the electrode is 360 μm.

[0062] S5. Frequency measurement: Use a frequency tester to measure the frequency as 92000 KHz.

[0063] S6. The measured and calculated resonance quality factor (Q) is 150000.

[0064] Comparative Example 1

[0065] 1. Prepare a quartz wafer: The outer shape is rectangular, the thickness of the quartz is 20 μm, the outer length is 750 μm, and the width is 500 μm.

[0066] 2. Groove processing: By means of photolithography and etching, rectangular grooves with a depth of 4 μm in the thickness direction of the quartz wafer are respectively formed in the central areas of the upper and lower surfaces of the quartz wafer. The length of the groove is 450 μm, and the width of the groove is 350 μm.

[0067] 4. Electrode preparation: Electrodes with the same thickness are respectively formed at the bottom of the quartz grooves by means of photolithography and coating. The thickness of Cr in the electrode is 5 nm, the thickness of Au is 130 nm, the length of the electrode is 430 μm, and the width of the electrode is 330 μm.

[0068] 5. Frequency measurement: Use a frequency tester to measure the frequency as 75800 KHz.

[0069] 6. The measured and calculated resonance quality factor (Q) is 75000.

[0070] Comparative Example 2

[0071] 1. Prepare a quartz wafer: The outer shape is rectangular, the quartz thickness is 20 μm, the outer length is 750 μm, and the width is 500 μm.

[0072] 2. Thin the quartz: Thin the quartz wafer by etching to 16 μm.

[0073] 4. Prepare the electrodes: Form electrodes on the upper and lower surfaces of the quartz wafer along the thickness direction through cleaning, yellow light process, and sputtering coating. The thickness of Cr in the electrode is 5 nm, the thickness of Au is 130 nm, the electrode length is 430 μm, and the electrode width is 330 μm.

[0074] 5. Measure the frequency. Use a frequency tester to measure the frequency as 72300 KHz.

[0075] 6. Measure and calculate the resonance quality factor (Q) to be 60000.

[0076] By comparing the frequencies and resonance quality factors of the embodiments of the present invention with the above two comparative cases, it can be seen that the embodiments of the present invention can obtain a higher resonance quality factor. The higher the quality factor, the better the frequency characteristics of the resonance device, and the higher the system detection sensitivity. Through the structural design of the present invention, the accuracy, resolution, and sensitivity of the device can be significantly improved as a whole.

[0077] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered by the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. A structure of an AT quartz crystal oscillator vibrating element, characterized in that, Comprising: A rectangular quartz wafer, on the upper and lower surfaces of which along its thickness direction, a first groove and a second groove are respectively provided; A first boss and a second boss, the first boss being integrally formed at the bottom of the first groove, and the second boss being integrally formed at the bottom of the second groove; A first electrode and a second electrode, the first electrode covering the top surface of the first boss, and the second electrode covering the top surface of the second boss.

2. The structure of the AT quartz crystal oscillator vibrating element according to claim 1, characterized in that, The first groove and the second groove are both circular grooves that penetrate into the quartz wafer, the first boss and the second boss are respectively located at the bottoms of the circular grooves, and both the first boss and the second boss are cylindrical in shape.

3. The AT quartz crystal oscillator vibrating element structure according to claim 2, wherein, Between the edges of the circular grooves on the upper and lower surfaces of the quartz wafer along the thickness direction and the first boss or the second boss within the circular grooves is an annular groove with a certain width. The top surfaces of the first boss and the second boss are respectively higher than the bottom of the annular groove, presenting a certain height difference, and the top surfaces of the first boss and the second boss are respectively lower than the corresponding outer surfaces of the quartz wafer.

4. The AT quartz crystal oscillator vibrating element structure according to claim 2, characterized in that, At least a partial projection of the first boss and the second boss coincides axially in the thickness direction of the quartz wafer.

5. The structure of the AT quartz crystal oscillator vibrating element according to claim 2, wherein, The axial projections of the first groove and the second groove in the thickness direction of the quartz wafer completely coincide.

6. The AT quartz crystal oscillator vibrating element structure according to claim 1, characterized in that The first electrode and the second electrode respectively include a Cr layer and an Au layer. The Cr layer is in contact and adhered to the top surface of the first boss or the second boss, and the Au layer is in contact and adhered to the Cr layer.

7. A method for preparing the AT quartz crystal oscillator vibrating element structure according to any one of claims 1-6, characterized in that, Including the following steps: Prepare a rectangular quartz wafer; Respectively process and form a first transition groove and a second transition groove on the upper and lower surfaces of the quartz wafer along its thickness direction through photolithography and etching processes; Form an annular groove and a cylindrical first boss at the bottom of the first transition groove through film coating, photolithography, and etching processes, and form an annular groove and a cylindrical second boss at the bottom of the second transition groove using the same process. The side walls of the first transition groove and the side walls of the second transition groove are respectively in smooth transition with the outer side walls of the corresponding annular grooves; Then, use a deposition process to form a first electrode on the top surface of the first boss and a second electrode on the top surface of the second boss. Both the first electrode and the second electrode are two layers, with the upper layer closer to the quartz wafer being the Cr layer and the lower layer farther from the quartz wafer being the Au layer; Finally, form the structure of an AT quartz crystal oscillator vibrating element.

8. A quartz crystal oscillator, characterized in that, Including the structure of an AT quartz crystal oscillator vibrating element as described in any one of claims 1 - 6 or the structure of an AT quartz crystal oscillator vibrating element prepared by the preparation method described in claim 7.

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