Crystal wafers for crystal oscillators

Abstract

To provide a structure capable of inspecting the characteristics of a crystal vibration piece as desired in a crystal wafer 10 which includes: a large number of crystal vibrating pieces 10a; a frame 10b connecting these pieces; and measurement electrodes 10c for inspecting the characteristics of the crystal vibration pieces, which are individually drawn out from each crystal vibration piece to a frame, and in which the thickness t of the crystal vibrating piece is smaller than the thickness T of the frame.SOLUTION: Each crystal vibrating piece is cantilevered by the frame. A recess 10d whose bottom surface 11da is flush with the main surface 10aa of the crystal vibrating piece is provided in a region close to each of the crystal vibrating pieces on at least one of the front and back surfaces of the frame, and the measurement electrode 10c is provided in a region including the recess.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a quartz wafer having a large number of quartz vibration pieces for a quartz oscillator.

Background Art

[0002] As the miniaturization of quartz oscillators progresses, quartz vibration pieces for quartz oscillators are increasingly manufactured in the state of wafers by photolithography technology. That is, on a quartz wafer blank of a predetermined cut, using photolithography technology and film formation technology, a large number of quartz vibration pieces for quartz oscillators are typically formed in a matrix.

[0003] Conventional examples of quartz wafers having a large number of quartz vibration pieces for quartz oscillators in a matrix are described in, for example, Patent Document 1, Patent Document 2, etc. Hereinafter, paying attention to the quartz wafer disclosed in Patent Document 2 and referring to FIG. 6, the outline of the conventional quartz wafer will be described. Here, FIG. 6(A) is a plan view of a quartz wafer 80 in which a large number of quartz vibration pieces 80a for a quartz oscillator are formed in a state of being connected to a frame 80b. FIG. 6(B) is an enlarged plan view focusing on one quartz vibration piece 80a and the frame 80b in the vicinity thereof in FIG. 6(A). FIG. 6(C) is a partial cross-sectional view along the broken line P or the broken line Q in FIG. 6(B).

[0004] When manufacturing a quartz oscillator, each quartz vibration piece 80a is folded from the completed quartz wafer 80 at the boundary of the broken line R in FIG. 6(B) and mounted in a container (not shown) for a quartz oscillator, and the final quartz oscillator is manufactured. However, before the quartz vibration piece80a is folded, the characteristics of each quartz vibration piece 80a are often inspected in the state of the quartz wafer 80. Therefore, a measurement electrode 80c is routed from each quartz vibration piece 80a to the frame 80b. Specifically, the measurement electrode 80c is routed from the excitation electrode 80d of the quartz vibration piece 80a through the lead-out electrode 80e to the frame 80b. Then, a measurement probe (not shown) is applied to the measurement electrode 80c to perform the target characteristic inspection. Further, the crystal resonator piece 80a detached and diced from the crystal wafer 80 is connected and fixed to a container (not shown) for a crystal resonator by a conductive adhesive or the like at the position of the lead-out electrode 80e.

[0005] By the way, among crystal wafers having a number of crystal resonator pieces 80a, there are those having a crystal resonator piece that vibrates in thickness-shear vibration. In the case of a crystal resonator piece that vibrates in thickness-shear vibration, as the frequency of the crystal resonator piece increases, the thickness of the vibration region of the crystal resonator piece becomes thinner. Therefore, in order to reduce breakage of the crystal wafer due to the thinning of the thickness of the vibration region, the frame is left at the thickness T (see FIG. 6(C)) of the crystal wafer blank, and only the region of the crystal resonator piece 80a is made to have a thickness t (<T) corresponding to the vibration frequency, which is thinner than the thickness of the frame 80b. In some cases, such a structure is adopted (Patent Document 2).

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the case of the crystal wafer 80 having a structure in which the thickness of the crystal resonator piece is thinner than the thickness of the frame, problems as described below may occur. In a quartz wafer 80 equipped with numerous quartz crystal oscillators 80a, as described above, a measuring electrode 80c for characteristic testing is routed from each quartz crystal oscillator 80a to the frame 80b so that characteristic testing can be performed in the wafer state. However, a step 80f (see Figure 6(C)) is created at the boundary between the frame 80b and the quartz crystal oscillators 80a due to the difference in their thicknesses. Moreover, the edge 80fa of this step 80f is knife-edge shaped due to the crystallinity of the quartz, making coverage by the measuring electrode 80d difficult, and the measuring electrode 80c is prone to breakage at the edge 80fa of the step 80f. When a break occurs, the intended measurement cannot be performed even if a measuring probe is applied to the measuring electrode 80c on the frame 80b. Therefore, even if the quartz crystal oscillator 80a itself is normal, it may be mismeasured as defective. This application has been made in view of the above points, and therefore the object of this invention is to provide a quartz wafer having a large number of quartz diaphragms for a quartz oscillator, wherein the thickness of the quartz diaphragms is thinner than the thickness of the frame, and the quartz wafer has a structure that allows the characteristics of the quartz diaphragms to be tested as desired in the wafer state. [Means for solving the problem]

[0008] To achieve this objective, the present invention provides a quartz wafer comprising a number of quartz crystal resonators for a quartz oscillator, a frame connecting these quartz crystal resonators and having a thickness greater than the thickness of the quartz crystal resonators, and measuring electrodes drawn individually from each quartz crystal resonator to the frame for characteristic testing of the quartz crystal resonators, The frame is characterized in that, at least one of its front and back surfaces has a recess in a region adjacent to each crystal vibrator, the bottom surface of which is flush with the main surface of the crystal vibrator, and the measuring electrode is provided in the region including the recess.

[0009] In carrying out this invention of a quartz wafer, it is preferable that the quartz wafer includes a slit provided in the boundary region between the quartz vibrator and the frame for breaking off the quartz vibrator from the quartz wafer, and connecting portions connecting the quartz vibrator and the frame at both ends of the slit, with the measuring electrode being wired to the connecting portion. In carrying out this invention of a quartz wafer, it is preferable to provide the recess on one side of the frame. In carrying out this invention of a quartz wafer, it is preferable to provide the recess on both sides of the frame. [Effects of the Invention]

[0010] According to the quartz wafer of this invention, a recess is provided in a predetermined region of the frame, the bottom surface of which is flush with the main surface of the quartz crystal vibrator, and a measuring electrode is provided in the region including this recess. As a result, the measuring electrode is provided on a continuous plane from the quartz crystal vibrator to the predetermined region of the frame. In other words, the measuring electrode is drawn out from the quartz crystal vibrator to the frame without passing through any steps. Therefore, the present invention can prevent the breakage of the measuring electrode, which may have occurred in the conventional invention due to the step at the boundary between the quartz crystal vibrator and the frame. Furthermore, since the measuring electrode, the lead electrode, and the excitation electrode are provided on a flush surface, the accuracy of patterning these electrodes is also improved. Furthermore, a configuration in which the quartz wafer is provided with a slit in the boundary region between the quartz crystal and the frame for breaking off the quartz crystal from the quartz wafer, and connecting portions connecting the quartz crystal and the frame are provided at both ends of this slit, is preferable because it allows for good breaking off of the quartz crystal from the quartz wafer and also allows for good routing of wiring in the boundary region between the quartz crystal and the recess. Furthermore, in the case where the recess is provided on one side of the frame's front or back surface, the area where the frame's thickness is reduced is limited to the portion of the frame where the recess is provided on one side, thus minimizing the reduction in the frame's strength, which is preferable. Furthermore, a configuration in which recesses are provided on both the front and back surfaces of the frame is preferable because it increases the number of surfaces on which measuring electrodes can be formed, thereby increasing the degree of freedom in forming the measuring electrodes. [Brief explanation of the drawing]

[0011] [Figure 1] This is an explanatory diagram of the quartz wafer 10 of the first embodiment. [Figure 2] This is an explanatory diagram of the cross-sectional structure of the quartz wafer 10 of the first embodiment, particularly the portion surrounding the measuring electrode. [Figure 3] This is an explanatory diagram of the process of separating the quartz crystal vibrators 10a from the quartz wafer 10 of the first embodiment. [Figure 4] This is a diagram illustrating another embodiment. [Figure 5] This is an explanatory diagram of yet another embodiment. [Figure 6] This is a diagram illustrating the conventional technology and its challenges. [Modes for carrying out the invention]

[0012] The following describes embodiments of the quartz wafer of this invention with reference to the drawings. Note that the figures used in this description are only schematic representations to the extent necessary to understand the invention. Furthermore, in the figures used in this description, similar components are indicated with the same number, and their descriptions may be omitted. Also, the shapes, dimensions, materials, etc., described below are merely preferred examples within the scope of this invention. Therefore, the present invention is not limited to the following embodiments.

[0013] 1. Quartz wafer of the first embodiment Figures 1 and 2 are explanatory diagrams of a quartz wafer 10 according to the first embodiment. In particular, Figure 1(A) is a plan view of the quartz wafer 10. Figure 1(B) is an enlarged plan view of portion M in Figure 1(A), that is, the portion containing the two quartz crystal oscillators 10a and the frame 10b in that vicinity. Figure 1(C) is an enlarged perspective view of portion N in Figure 1(B), that is, the vicinity of the boundary between one quartz crystal oscillator 10a and the frame 10b. Furthermore, Figure 2(A) is a cross-sectional view along the PP line in Figure 1(C), and Figure 2(B) is a cross-sectional view along the QQ line in Figure 1(C).

[0014] The quartz wafer 10 of the first embodiment shows an example of an AT-cut quartz wafer with a circular planar shape. The coordinate axes X, Y′, and Z′ shown in FIG. 1(A) indicate the crystal axes of the quartz in the AT-cut quartz wafer 10. The details of the AT-cut quartz piece itself are described, for example, in the literature: "Explanation and Application of Quartz Devices", The Japan Society of Quartz Devices, 4th Edition, March 2002, page 7, etc., so the description thereof is omitted here.

[0015] The quartz wafer 10 of the first embodiment includes a large number of quartz resonator pieces 10a for a quartz oscillator, a frame 10b that connects these quartz resonator pieces 10a and is thicker than the thickness of the quartz resonator pieces 10a, and measurement electrodes 10c that are individually drawn from each of the quartz resonator pieces 10a to the frame 10b for the purpose of inspecting the characteristics of the quartz resonator pieces 10a. That is, each quartz resonator piece 10a is supported in a cantilever manner on the frame 10b, and the measurement electrodes 10c are drawn from each of the quartz resonator pieces 10a to the frame 10b. Moreover, the quartz wafer 10 of the first embodiment has recesses 10d in regions on one of the front and back surfaces of the frame 10b that are close to each of the quartz resonator pieces 10a, where the bottom surface 10da is flush with the main surface 10aa of the quartz resonator piece 10a (see FIGS. 1(C), 2(A), and (B)). The measurement electrodes 10c are provided in the regions including the recesses 10d. Each of the quartz resonator pieces 10a includes excitation electrodes 10f provided on the front and back, and lead electrodes 10g drawn from the respective excitation electrodes 10f to the ends of the quartz resonator pieces 10a on the frame 10b side. As shown in FIG. 1(C), the wiring from the lead electrodes on the back surface side of the quartz wafer 10 to the measurement electrodes on the front surface side of the quartz wafer 10 is carried out via the inner wall of the slit 10ea and the connecting portions 10eb at both ends of the slit 10ea.

[0016] Here, the thickness of the frame 10b is designated as T, and the thickness of the quartz resonator piece 10a is designated as t (<T). The frame 10b thickness T is, for example, about 80 to 150 μm, although it is not limited to this. The thickness t of the quartz resonator piece 10a is a thickness determined by the frequency of the quartz resonator piece 10a. Also, the planar shape of the concave portion 10d is preferably a square shape. This is because probing during characteristic inspection is easier when the shape is square. Also, the area of the concave portion 10d is the area required for probing by the measurement probe. For example, as shown in Fig. 1(C), when the dimension along the X-axis of the crystal is represented as a and the dimension along the Z'-axis of the crystal is represented as b, although not limited thereto, the dimension a is preferably a value selected from, for example, 50 to 170 μm, and the dimension b is preferably a value selected from, for example, 100 to 500 μm. Furthermore, the crystal wafer 10 of this embodiment has a slit 10ea for detaching the crystal vibrating piece 10a from the crystal wafer 10 in the boundary region between the crystal vibrating piece 10a and the frame 10b, and both sides of the slit 10ea are connecting portions 10eb that connect the crystal vibrating piece 10a and the frame 10b, and is provided with a detaching portion 10e. Therefore, strictly speaking, the measurement electrode 10c has a structure flush with the lead-out electrode 10g on the crystal vibrating piece 10a side at the location of the connecting portion 10eb.

[0017] In the case of the crystal wafer 10 of the first embodiment, when performing characteristic inspection in the wafer state, the probe (not shown) of the characteristic inspection machine is applied to the measurement electrode 10c within the concave portion 10d. Since the measurement electrode 10c exists on the same plane as the main surface 10aa of the crystal vibrating piece 10a due to the action of the concave portion 10d, no disconnection due to a step occurs in the measurement electrode 10c, and thus the characteristic inspection can be accurately performed. When detaching the crystal vibrating piece 10a from this crystal wafer 10, as shown in Figs. 3(A) and (B), by applying a predetermined force to the crystal vibrating piece 10a, detachment can be easily performed by detaching along the region along the line R including the slit 10ea.

[0018] 2. Second Embodiment Next, the second embodiment will be described. Fig. 4 is an explanatory diagram thereof, and is a cross-sectional view of the main part corresponding to Fig. 2(A). In the first embodiment, the recess 10d was provided on only one of the front and back surfaces of the frame 10b, whereas the characteristic of the quartz wafer 20 in the second embodiment is that the recess 10d is provided on both the front and back surfaces of the frame 10b. However, in the example of Figure 4, the measuring electrode 10c is provided only in the region including one of the recesses of the frame 10b. The measuring electrode 10c may be provided in the region including the recesses on both the front and back surfaces of the frame 10b. Providing recesses on both the front and back surfaces of the frame is preferable because it increases the number of surfaces on which the measuring electrode can be formed, thus increasing the degree of freedom in forming the measuring electrode.

[0019] 3. Third Embodiment Next, a third embodiment will be described. Figure 5 is an explanatory diagram and is a perspective view of the main part corresponding to Figure 1(C). In the first and second embodiments, two recesses 10d were provided on one side of the frame 10b for a single quartz crystal vibrator 10a, whereas in the quartz wafer 30 of the third embodiment, one recess 10d is provided on one side of the frame 10b, and two measuring electrodes 10c are provided in the region including this one recess. Since the recess 10d is shared for both measuring electrodes, it is easier to expand the flat area of ​​the recess compared to the case where two recesses are provided separately, which is preferable.

[0020] 4. Other Embodiments In the embodiment described above, the measuring electrode is shown as being provided within the recess, but the measuring electrode may also be provided extending from within the recess onto the frame surrounding the recess. Furthermore, while AT-cut quartz wafers were used as an example of quartz wafers, other cuts such as Z-cut or double-rotation cut quartz wafers are also acceptable. In addition, the planar shape of the quartz wafer is not limited to round; other shapes such as squares are also acceptable. Furthermore, although the embodiment shows an example where the extraction electrode 10g of the quartz crystal diaphragm 10a is on the +X side of the quartz crystal, the extraction electrode 10g may also be drawn out on the -X side. Moreover, the present invention can also be applied to a quartz wafer having a large number of quartz crystal diaphragms, the ends of which are along the Z' axis of the quartz crystal diaphragm are used as support portions. [Explanation of Symbols]

[0021] 10: Quartz wafer of the first embodiment, 10a: Quartz diaphragm, 10aa: Main surface of the quartz crystal vibrator 10b: Frame, 10c: Measuring electrode, 10d: Recess, 10da: Bottom surface of the recess 10e: Fold-off section 10ea: Slit, 10eb: Connecting part, 10g: Extraction electrode, 10f: Excitation electrode 20: Quartz wafer of the second embodiment, 30: Quartz wafer of the third embodiment

Claims

1. A quartz wafer comprising a plurality of quartz crystal oscillators, a frame connecting these quartz crystal oscillators and having a thickness greater than the thickness of the quartz crystal oscillators, and measuring electrodes individually drawn from each of the quartz crystal oscillators to the frame for characteristic testing of the quartz crystal oscillators, A quartz wafer characterized in that, at least one of the front and back surfaces of the frame is provided with a recess in a region adjacent to each of the quartz crystal vibrators, the bottom surface of which is flush with the main surface of the quartz crystal vibrator, and the measuring electrode is provided within the recess and not on the main surface of the thick frame.

2. A quartz wafer comprising a plurality of quartz crystal oscillators, a frame connecting the quartz crystal oscillators and having a thickness greater than the thickness of the quartz crystal oscillators, and measuring electrodes drawn individually from each of the quartz crystal oscillators to the frame for characteristic testing of the quartz crystal oscillators, The frame is provided with a recess in a region adjacent to each of the crystal resonators on at least one of its front and back surfaces, the bottom surface of which is flush with the main surface of the crystal resonator. The measuring electrode is provided on the bottom surface of the recess, and the recess is provided individually for each crystal vibrator, characterized in that the crystal wafer.

3. A quartz wafer comprising a plurality of quartz crystal oscillators, a frame connecting the quartz crystal oscillators and having a thickness greater than the thickness of the quartz crystal oscillators, and measuring electrodes drawn individually from each of the quartz crystal oscillators to the frame for characteristic testing of the quartz crystal oscillators, The frame is provided with a recess in a region adjacent to each of the crystal resonators on at least one of its front and back surfaces, the bottom surface of which is flush with the main surface of the crystal resonator. A quartz wafer characterized in that the measuring electrode is provided on the bottom surface of the recess, and the recess is provided individually for each measuring electrode.

4. A quartz wafer comprising a plurality of quartz crystal oscillators, a frame connecting the quartz crystal oscillators and having a thickness greater than the thickness of the quartz crystal oscillators, and measuring electrodes drawn individually from each of the quartz crystal oscillators to the frame for characteristic testing of the quartz crystal oscillators, One side of the frame is provided with recesses in regions adjacent to each of the crystal oscillators, The measuring electrode is provided in the region including the recess, On one of the aforementioned surfaces, the bottom surface of the recess and one of the main surfaces of the crystal oscillating element are flush with each other. A quartz wafer characterized in that the thickness of the frame at the location where the recess is formed is greater than the thickness of the quartz crystal diaphragm, and due to this difference in thickness, the other surface of the frame and the other main surface of the quartz crystal diaphragm are not flush.

5. A quartz wafer according to claim 4, wherein the measuring electrode is provided on the bottom surface of the recess, and the recess is provided individually for each quartz vibrator.

6. A quartz wafer according to claim 4, wherein the measuring electrode is provided on the bottom surface of the recess, and the recess is provided individually for each measuring electrode.

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