AT-cut high-fundamental-frequency quartz wafer, preparation method and piezoelectric device
By designing the AT-cut high-basic frequency structure on the quartz wafer, combining the expanded inclined fixed part and optimized electrode layout, the problem of taking into account the high frequency and mechanical strength of small and thin quartz wafers is achieved, and a higher level of The frequency stability and shock resistance reduce power consumption.
Patent Information
- Application Number
- CN202411300860.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-18
- Publication Date
- 2025-02-07
AI Technical Summary
Existing small and thin quartz wafers are difficult to take into account both high frequency and mechanical strength, and there are problems of poor frequency stability and high power consumption.
The AT-cut high-basic frequency quartz chip design is adopted. Vibration part is formed by etching on the sheet body, combined with the expanded inclined fixed part design, the crystal impedance is reduced, the Q value is increased, and the vibration effect is improved by optimizing the electrode layout and wafer layout. and seismic resistance.
It effectively reduces the difficulty of etching, improves the frequency stability and shock resistance of the crystal, reduces power consumption, and improves the reliability and stability of the circuit.
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Figure CN119403426A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of piezoelectric devices, and in particular to an AT-cut high fundamental frequency quartz wafer and a preparation method thereof, and a piezoelectric device. Background Art
[0002] The piezoelectric device is formed by bonding a substrate and a cover. A quartz wafer is installed in the space formed by the substrate and the cover. The quartz wafer is contained in an airtight and closed space. The quartz wafer includes a sheet body and electrodes arranged on the sheet body. When a voltage is applied, a part of the sheet body vibrates through the inverse piezoelectric effect and the piezoelectric effect.
[0003] In recent years, inverted mesa-type quartz wafers have been able to achieve both high frequency and mechanical strength of quartz wafers, and further miniaturization has been required. In such small and thin quartz wafers, there are problems such as failure to obtain stable signals from quartz, insufficient energy confinement, and poor frequency stability over a wide temperature range in the graph showing the frequency-temperature characteristics.
[0004] The relevant document discloses an inverted table-type quartz vibration plate with excellent mass productivity and a high vibration part occupancy ratio, which is used to solve the problem of an increase in the proportion of residues from the thick-walled part to the thin-walled part, resulting in a decrease in the effective area of the thin-walled part, by adjusting the cutting angle.
[0005] Regarding the above-mentioned related technologies, there is a problem that the etching process is complicated. Summary of the invention
[0006] In order to reduce the difficulty of etching, effectively reduce the crystal impedance, improve the Q value, reduce power consumption, and comprehensively improve the reliability and stability of the circuit, the purpose of this application is to provide an AT-cut high fundamental frequency quartz wafer and its preparation method, and a piezoelectric device.
[0007] In the first aspect, the AT-cut high fundamental frequency quartz wafer provided in this application adopts the following technical solution:
[0008] An AT-cut high fundamental frequency quartz wafer, comprising:
[0009] A sheet body, comprising a fixed portion, and a vibrating portion integrally formed by etching in a space enclosed by the fixed portion, wherein the distance between the vibrating portion and a free end of the fixed portion is less than 20 μm;
[0010] A pair of electrodes, each electrode comprising an electrically connected excitation electrode and an extraction electrode, wherein the pair of excitation electrodes are disposed on two opposite sides of the vibration part and are extracted to the dispensing end of the fixing part through corresponding extraction electrodes;
[0011] Wherein, the fixing portion is perpendicular to the two sides of the dispensing end and takes the free end of the fixing portion as a starting point, and is at least partially arranged in an expansion-type tilted manner.
[0012] Optionally, the vibration part is arranged to pass through the free end of the fixing part.
[0013] Optionally, the ratio of the width of the free end of the fixing portion to the width of the vibration portion is 1.1-1.35.
[0014] Optionally, the ratio of the width of the free end of the fixing portion to the width of the vibration portion is 1.2-1.28.
[0015] Optionally, the area of the vibration part is 3-5 times the area of the excitation electrode.
[0016] Optionally, the projection of the at least part on the corresponding side of the fixing portion accounts for at least 15% of the length of the corresponding side.
[0017] Optionally, the projection of the at least part on the corresponding side of the fixing portion accounts for 25-75% of the length of the corresponding side.
[0018] Optionally, the projection of the at least part on the corresponding side of the fixing portion accounts for 45-55% of the length of the corresponding side.
[0019] In the second aspect, the preparation method of the AT-cut high fundamental frequency quartz wafer provided in the present application adopts the following technical solution:
[0020] The method for preparing an AT-cut high fundamental frequency quartz wafer comprises the following steps:
[0021] A chip wafer is prepared, on which a plurality of slices are arranged in an array;
[0022] Cutting the wafer to obtain a plurality of slices;
[0023] The sheet body is subjected to electrode coating processing to obtain an AT-cut high fundamental frequency quartz wafer.
[0024] In a third aspect, the piezoelectric device provided in this application adopts the following technical solution:
[0025] A piezoelectric device comprises the AT-cut high fundamental frequency quartz wafer.
[0026] In summary, the present application includes at least one of the following beneficial technical effects:
[0027] 1. While not requiring complicated etching processes, it reduces the difficulty of etching, effectively reduces crystal impedance, improves Q value, reduces power consumption, and comprehensively improves the reliability and stability of the circuit;
[0028] 2. Improve the vibration effect of the vibration zone, reduce vibration energy transfer and boundary effect, and thus improve the shock resistance of the chip;
[0029] 3. During the preparation process, the chip layout is set to greatly improve the chip utilization rate, and effectively solve the problem of difficult etching accuracy control in traditional through etching. BRIEF DESCRIPTION OF THE DRAWINGS
[0030] Figure 1 It is a schematic diagram of the structure of a piezoelectric device according to one of the technical solutions of the present application;
[0031] Figure 2 It is a structural schematic diagram of an AT-cut high fundamental frequency quartz wafer according to one of the technical solutions of the present application;
[0032] Figure 3 It is a structural schematic diagram of an AT-cut high fundamental frequency quartz wafer according to one of the technical solutions of the present application;
[0033] Figure 4 It is a structural schematic diagram of an AT-cut high fundamental frequency quartz wafer according to one of the technical solutions of the present application;
[0034] Figure 5 It is a schematic diagram of the structure of a chip wafer described in one of the technical solutions of the present application;
[0035] Figure 6 yes Figure 5 A magnified view of part A;
[0036] Figure 7 It is a schematic diagram of the structure of the quartz wafer described in Comparative Example 1 of the present application;
[0037] Figure 8 It is a crystal impedance distribution diagram of the products described in Example 1 and Comparative Example 1 of the present application;
[0038] Fig. 9 This is the quality factor distribution diagram of the products described in Example 1 and Comparative Example 1 of the present application
[0039] Fig.10 It is the DLD2 distribution diagram of the products described in Example 1 and Comparative Example 1 of the present application.
[0040] Description of reference numerals:
[0041] 100. AT-cut high fundamental frequency quartz crystal chip; 1. chip body; 2. fixing part; 20. dispensing end; 21. free end; 3. vibration part; 4. electrode; 40. excitation electrode; 41. lead-out electrode; 5. chip wafer; 6. piezoelectric device; 60. packaging body. DETAILED DESCRIPTION
[0042] The following is combined with Figure 1 -Attached Fig.10 , further details of this application are given.
[0043] It should be understood that the terms such as “having”, “including” and “comprising” used herein do not exclude the existence or addition of one or more other elements or combinations thereof.
[0044] like Figure 1-4 As shown, the present application discloses an AT-cut high fundamental frequency quartz wafer, referring to Figure 1 The AT-cut high fundamental frequency quartz wafer includes a wafer body 1 and a pair of electrodes 4.
[0045] The sheet 1 includes a fixing portion 2 and a vibration portion 3 formed integrally by etching in the space enclosed by the fixing portion 2. In this embodiment, the sheet 1 is a quartz substrate of AT with a certain thickness. The thickness of the quartz substrate is set according to actual needs and can be 60-80 μm. In one specific embodiment, the thickness of the substrate is 70 μm.
[0046] The vibration part 3 is obtained by etching a part of the sheet 1. The vibration part 3 is thinner than the sheet 1 itself. The specific thickness is set according to actual needs. For a quartz wafer with a fundamental frequency of 200Mhz, the thickness is set to 6μm.
[0047] The fixed part 2 is composed of the part of the sheet 1 other than the vibration part 3. The end of the fixed part 2 used for glue dispensing and fixing is defined as the glue dispensing end 20 of the fixed part 2, and the end of the fixed part 2 opposite to the glue dispensing end 20 is the free end 21. The direction from the glue dispensing end 20 to the free end 21 is the length direction of the fixed part 2, and the direction parallel to the fixed part 2 and perpendicular to the length direction is the width direction of the fixed part 2. The distance between the vibration part 3 and the free end 21 of the fixed part 2 is less than 20μm, that is, the vibration part 3 is arranged close to the free end 21 of the fixed part 2. On the basis of ensuring the etching effect, exemplarily, the vibration part 3 is arranged through the free end 21 of the fixed part 2. This design can increase the area of the vibration part 3, improve the vibration effect, and improve the shock resistance on the basis of miniaturization of the quartz wafer. However, in the traditional etching process, the closer the vibration part 3 is to the free end 21 of the fixed part 2, the smaller the thickness of the vibration part 3, which increases the difficulty of its preparation.
[0048] A pair of electrodes 4 is attached to the sheet body 1, each electrode 4 includes an excitation electrode 40 and an extraction electrode 41 which are electrically connected, the pair of excitation electrodes 40 are disposed on two opposite sides of the vibration part 3 (two sides of the vibration part 3 along the thickness direction), and are led to the glue dispensing end 20 of the fixing part 2 through the corresponding extraction electrodes 41, and are spaced apart at the glue dispensing end 20 along the width direction of the sheet body 1;
[0049] The fixing portion 2 is perpendicular to the two sides of the dispensing end 20 and is at least partially inclined with the free end 21 of the fixing portion 2 as the starting point. In this embodiment, the two sides of the fixing portion 2 opposite to each other along the width direction are at least partially inclined, and the inclined portion is expanded and extended with the free end 21 of the fixing portion 2 as the starting point toward the dispensing end 20 of the fixing portion 2 and intersects with the corresponding side.
[0050] During use, the vibration part 3 is first formed, and the vibration part 3 is excited by the electrode 4 at the required frequency. With this technical solution, by setting bevels on the two opposite sides of the fixed part 2 along the width direction, the edge of the outer shape is lost, the vibration effect of the vibration area is guaranteed, the vibration energy transmission and boundary effect are reduced, and the vibration resistance of the chip is improved. Furthermore, the crystal impedance is effectively reduced, the Q value is increased, the power consumption is reduced, and the reliability and stability of the circuit are comprehensively improved.
[0051] In another technical solution, the ratio of the width of the free end 21 of the fixed part 2 to the width of the vibrating part 3 is 1.1-1.35. The width of the free end 21 of the fixed part 2 and the width of the vibrating part 3 are in the same direction. The width of the free end 21 of the fixed part 2 is set to W2, and the width of the vibrating part 3 is set to W1, then W2 / W1=1.1-1.35, that is, W2 / W1 includes but is not limited to any one of 1.1, 1.15, 1.2, 1.25, 1.3, 1.35, and any ratio value between 1.1-1.35 is included. With this technical solution, the ratio of the width of the free end 21 of the fixed part 2 to the width of the vibrating part 3 is limited to 1.1-1.35, thereby limiting the starting point of the edge loss, so as to improve the shock resistance of the chip while ensuring the supporting strength of the fixed part 2 as an outer frame. In order to further improve the effect of improving the vibration resistance of the chip, reduce the crystal impedance, increase the Q value, reduce the power consumption, and comprehensively improve the reliability and stability of the circuit, the ratio of the width of the free end 21 of the fixing part 2 to the width of the vibration part 3 is set to 1.2-1.28. That is, W2 / W1 includes but is not limited to any one of 1.2, 1.25, and 1.28, and any ratio value between 1.2-1.28 is included.
[0052] In another technical solution, the area of the vibration part 3 is 3-5 times the area of the excitation electrode 40, the projections of a pair of excitation electrodes 40 along the thickness direction of the vibration part 3 overlap, and the area of the vibration part 3 is 3-5 times the area of the excitation electrode 40 on the corresponding side. With this technical solution, the vibration effect of the vibration area is guaranteed by limiting the area ratio of the vibration part 3 to the excitation electrode 40, effectively reducing the crystal impedance, improving the Q value, reducing power consumption, and comprehensively improving the reliability and stability of the circuit.
[0053] In another technical solution, the projection of at least part of the corresponding side of the fixing part 2 accounts for at least 15% of the length of the corresponding side. That is, the at least part of the expansion-type inclined setting is defined as the hypotenuse part, and the projection length of the hypotenuse part on the corresponding side accounts for at least 15% of the corresponding side, and at most 100%. Considering the stability and shock resistance, it is further preferred that the projection of at least part of the corresponding side of the fixing part 2 accounts for 25-75% of the length of the corresponding side. That is, the projection length of the hypotenuse part on the corresponding side accounts for at least 25% of the corresponding side, and at most 75%. Considering the improvement effect further, it is further preferred that the projection of at least part of the corresponding side of the fixing part 2 accounts for 45-55% of the length of the corresponding side. That is, the projection length of the hypotenuse part on the corresponding side accounts for at least 45% of the corresponding side, and at most 55%. This technical solution is adopted to improve the comprehensive improvement effect of the shock resistance and stability of the quartz wafer.
[0054] like Figure 5-6 As shown, the present application also discloses a method for preparing an AT-cut high fundamental frequency quartz wafer, comprising the following steps:
[0055] S1, depositing an etching-resistant metal layer material on the surface of the wafer 5, and then forming a photoresist film on the surface of the etching-resistant metal layer, and exposing it through a photolithography mask to form an exposure pattern;
[0056] The same process is performed on the lower surface of the wafer 5 to produce a symmetrical pattern on the back side;
[0057] S2. Use the corresponding metal etching solution to remove the metal layer in the protected area not covered by the photoresist. Figure 5 and Figure 6 The metal layer removed in this step corresponds to the area to be etched through on the wafer 5 .
[0058] S3, the chip wafer 5 body adopts wet etching, dry etching or laser etching processing technology to produce the vibration area corresponding to the vibration part 3; wherein, in one embodiment, the quartz wafers are arranged in an array on the chip wafer 5, and along the length direction of the quartz wafer, any two adjacent crystals are arranged so that the dispensing end 20 is connected to the dispensing end 20 or the free end 21 is connected to the free end 21, for example, refer to Figure 5 For any row of quartz wafers, from top to bottom, they are marked as P1, P2, P3, P4, P5..., wherein the glue dispensing ends 20 of the fixed parts 2 of P1 and P2 are connected, the free ends 21 of the fixed parts 2 of P2 and P3 are connected, the glue dispensing ends 20 of the fixed parts 2 of P4 and P5 are connected, and so on. For any row of quartz wafers, except for the first and last quartz wafers, the other vibration parts 3 are connected, and the subsequent cutting can form a penetrating vibration part 3, which ensures the effect of penetrating etching while effectively reducing the process difficulty, and at the same time, greatly improves the wafer utilization rate, and effectively solves the problem of difficult etching accuracy control in traditional penetrating etching.
[0059] S4, depositing an etching-resistant metal layer material on the surface of the entire wafer 5, and then forming a photoresist film on the surface of the etching-resistant metal layer, and exposing through a photolithography mask to form an exposure pattern;
[0060] The same process is performed on the lower surface of the wafer 5 to produce a symmetrical pattern on the back side;
[0061] S5. Use the corresponding metal etching solution to remove the metal layer in the protected area not covered by the photoresist. Figure 5 and Figure 6 The metal layer removed in this step corresponds to the area to be etched through on the wafer 5 .
[0062] S6. The chip wafer 5 body is subjected to wet etching, dry etching or laser etching to produce a removal through portion. The metal layer removed in this step corresponds to the area to be etched through on the chip wafer 5.
[0063] In this embodiment, electrodes 4 may be further pre-arranged.
[0064] S7, cutting the chip wafer 5, specifically using a blade or laser cutting process, cutting and separating the individual slices 1 along the cutting lines, thereby realizing the production of AT-cut high fundamental frequency quartz wafers.
[0065] Reference Figure 1 The present application also discloses a piezoelectric device. The piezoelectric device 6 includes the above-mentioned AT-cut high fundamental frequency quartz wafer 100 and a package body 60 for packaging the above-mentioned AT-cut high fundamental frequency quartz wafer 100.
[0066] <Example 1>
[0067] Reference Figure 1 , preparing a piezoelectric device with a package size of 3225, the piezoelectric device comprising an AT-cut high fundamental frequency quartz wafer, and a package body for packaging the AT-cut high fundamental frequency quartz wafer, wherein the AT-cut high fundamental frequency quartz wafer comprises:
[0068] The sheet body has a thickness of 70 μm, and the distance between the vibration part and the free end of the fixed part is 15 μm; wherein the ratio of the width of the free end of the fixed part to the width of the vibration part is 1.25;
[0069] A pair of electrodes, the area of the vibrating portion is 3.5 times the area of the excitation electrode;
[0070] The fixing portion is perpendicular to the two sides of the dispensing end (20) and takes the free end of the fixing portion as a starting point, and is at least partially arranged in an expansion-type tilted manner, and at least a portion of the projection on the corresponding side of the fixing portion accounts for 50% of the length of the corresponding side.
[0071] <Comparative Example 1>
[0072] Reference Figure 7 , a piezoelectric device with a package size of 3225 is prepared, which is the same as Example 1, except that the periphery of the AT-cut high fundamental frequency quartz wafer is rectangular and no edge missing treatment is performed.
[0073] Experiment 1
[0074] The products obtained in Example 1 and Comparative Example 1 were tested for vibration parameters, including crystal impedance, quality factor, and DLD2 value. The test results are detailed in Figure 8-9 , and Table 1.
[0075] Table 1
[0076]
[0077]
[0078] according to Figure 8 Combined with Table 1 above, it can be seen that the piezoelectric resonance phenomenon of the quartz crystal in the piezoelectric device can be simulated by an equivalent circuit. The equivalent circuit includes crystal impedance R, dynamic inductance L, etc.; the smaller the crystal impedance, the smaller the power consumption required for the crystal oscillator to start, and the smaller the power consumption, the easier it is for the crystal oscillator to start under the same excitation power. According to Table 1 above, the product of Example 1 has a smaller crystal impedance than the product of Comparative Example 1, that is, the crystal impedance has a significant downward trend. The crystal impedance value of Comparative Example 1 is 12.82Ω, and the crystal impedance value of Example 1 is concentrated at 9.91Ω, a decrease of 22.6%, and the product has good stability.
[0079] Q is the quality factor. The higher the Q value, the better the frequency stability of the crystal oscillator. Fig. 9 In combination with the above Table 1, it can be seen that the product of Example 1 has a larger Q value than the product of Comparative Example 1, that is, the Q value has a significant improvement trend, increasing by 9.2%.
[0080] DLD2 (unit: ohm) is the difference between the maximum and minimum values of the load resonant resistance at different excitation levels. When DLD2 is small, it means that the load resonant resistance changes less at different levels, and the reliability and stability of the circuit are improved; according to Fig.10 In combination with the above Table 1, it can be seen that the product of Example 1 has a smaller DLD2 value than the product of Comparative Example 1, that is, the reliability and stability of the circuit are improved.
[0081] Experiment 2
[0082] The products obtained in Example 1 and Comparative Example 1 were tested for vibration acceleration sensitivity. The test results are shown in Table 2.
[0083] Table 2
[0084] 60Hz vibration 200Hz vibration Example 1 0.055ppm / G 0.011ppm / G Comparative Example 1 0.025ppm / G 0.006ppm / G
[0085] According to Table 2, the vibration acceleration sensitivity of Example 1 under different test conditions is much lower than that of Example 1.
[0086] The embodiments of this specific implementation are all preferred embodiments of the present application, and are not intended to limit the protection scope of the present application. The same components are represented by the same figure marks. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the protection scope of the present application.
Claims
1. AT-cut high fundamental frequency quartz wafer, characterized in that: include: A sheet body (1) comprising a fixed portion (2), and a vibration portion (3) formed integrally by etching in a space enclosed by the fixed portion (2), wherein the distance between the vibration portion (3) and a free end (21) of the fixed portion (2) is less than 20 μm; A pair of electrodes (4), each electrode (4) comprising an electrically connected excitation electrode (40) and an extraction electrode (41), the pair of excitation electrodes (40) being arranged on two opposite sides of the vibration part (3) and being extracted to a dispensing end (20) of the fixing part (2) through corresponding extraction electrodes (41); Wherein, the fixing portion (2) is perpendicular to the two sides of the dispensing end (20) and takes the free end (21) of the fixing portion (2) as the starting point, and is at least partially arranged in an expansion-type tilted manner.
2. The AT-cut high fundamental frequency quartz wafer according to claim 1, characterized in that: The vibrating portion (3) is arranged to penetrate the free end (21) of the fixing portion (2).
3. The AT-cut high fundamental frequency quartz wafer according to claim 1, characterized in that: The ratio of the width of the free end (21) of the fixing portion (2) to the width of the vibration portion (3) is 1.1-1.
35.
4. The AT-cut high fundamental frequency quartz wafer according to claim 3, characterized in that: The ratio of the width of the free end (21) of the fixing portion (2) to the width of the vibration portion (3) is 1.2-1.
28.
5. The AT-cut high fundamental frequency quartz wafer according to claim 1, characterized in that: The area of the vibration part (3) is 3-5 times the area of the excitation electrode (40).
6. The AT-cut high fundamental frequency quartz wafer according to claim 1, characterized in that: The projection of the at least part on the corresponding side of the fixing portion (2) accounts for at least 15% of the length of the corresponding side.
7. The AT-cut high fundamental frequency quartz wafer according to claim 6, characterized in that: The projection of the at least part on the corresponding side of the fixing portion (2) accounts for 25-75% of the length of the corresponding side.
8. The AT-cut high fundamental frequency quartz wafer according to claim 7, characterized in that: The projection of the at least part on the corresponding side of the fixing portion (2) accounts for 45-55% of the length of the corresponding side.
9. A method for preparing an AT-cut high fundamental frequency quartz wafer, characterized in that: The following steps are involved: Prepare a chip wafer (5) on which a plurality of sheets (1) as described in any one of claims 1 to 8 are arranged in an array; Cutting a wafer (5) to obtain a plurality of slices (1); The electrode (4) is plated on the sheet (1) to obtain an AT-cut high fundamental frequency quartz wafer.
10. A piezoelectric device, characterized in that It comprises the AT-cut high fundamental frequency quartz wafer (100) as claimed in any one of claims 1 to 8.