Patent Application
20240213954
This patent application claims priority to Chinese Application No. 202211657114.4, filed on Dec. 22, 2022 and entitled “Quartz crystal resonator and manufacturing method thereof,” which is hereby incorporated by reference herein as if reproduced in its entirety.
The present disclosure relates to the field of crystal resonators, and in particular embodiments, to a quartz crystal resonator and manufacturing method thereof. Specifically, the quartz crystal resonator can maintain a vibration frequency deviation in a small range for an operating temperature range from about −40° C. to about 125° C., and has good ambient temperature tolerance.
With the advancement of the integrated circuit technologies, various machine controls that could only be handled by large scale computer systems in the past can now be controlled using semiconductor integrated circuits (such as large-scale integration (LSI), integrated circuits (IC), etc.). In the operation of IC and LSI, the frequency is indispensable. A crystal resonator provides a simple, low-cost and high-accuracy frequency source, is applicable for a wide frequency range and is a suitable choice for many applications, e.g., in equipment for satellite communications and mobile communications, and also in automobiles, televisions, computers or some home appliances.
Technical advantages are generally achieved, by embodiments of this disclosure which describe a quartz crystal resonator and manufacturing method thereof.
In an exemplary aspect of the present disclosure, a quartz crystal resonator is provided. The quartz crystal resonator includes a quartz crystal cut from a quartz bar, and the quartz bar has a light axis, an electrical axis and a mechanical axis perpendicular to one another. A first angle, rotated by about 35 degrees to about 36 degrees with the electrical axis as the rotating axis, is formed between a major face of the quartz crystal and the light axis, and a second angle, rotated with the light axis as the rotating axis, is formed between the major face and the electrical axis, such that the quartz crystal has a vibration frequency deviation inflection point from about 30 degrees Celsius to about 45 degrees Celsius.
In another exemplary aspect of the present disclosure, a method of manufacturing a quartz crystal resonator is provided. The method comprises: receiving a quartz bar, the quartz bar having a light axis, an electrical axis, and a mechanical axis perpendicular to one another; with the electrical axis as the rotating axis, rotating a first angle of about 35 degrees to about 36 degrees from the direction of the light axis toward the direction of the mechanical axis, and then with the light axis as the rotating axis, rotating a second angle of about 10 degrees to about 12 degrees from the direction of the electric axis toward the direction of the mechanical axis to obtain a cutting plane; and cutting the quartz bar along the cutting plane to obtain a quartz crystal.
In yet another exemplary aspect of the present disclosure, a method of manufacturing a quartz crystal resonator is provided. The method comprises: receiving a quartz bar, the quartz bar having a light axis, an electrical axis, and a mechanical axis perpendicular to one another. axis; rotating the quartz bar to be at an AT-cut angle; based on the AT-cut angle, and with the light axis as the rotating axis, rotating a correction angle from the direction of the electrical axis toward the direction of the mechanical axis, to obtain a cutting plane; and cutting the quartz bar along the cutting plane to obtain a quartz crystal; wherein, through the correction angle, the cut quartz crystal has a vibration frequency deviation between −20 ppm and +20 ppm in an operating temperature range from about −40 degrees Celsius to about 125 degrees Celsius.
In yet another aspect of the present disclosure, a quartz crystal resonator is provided. The quartz crystal resonator includes a quartz crystal obtained from a quartz bar, the quartz bar having a light axis, an electrical axis along a length of the quartz bar, and a mechanical axis that are perpendicular to one another, and the quartz crystal having a major face cut from the quartz bar along a cutting plane, wherein the cutting plane has a first angle of about 35° to about 36° with the light axis and has a second angle with the electric axis, the first angle being obtained by rotation about the electric axis, and the second angle being obtained by rotation about the light axis, such that the quartz crystal has a vibration frequency deviation inflection point in a range from about 30° C. to about 45° C.
In yet another aspect of the present disclosure, a method for making a quartz crystal resonator is provided. The method includes: obtaining a quartz bar, the quartz bar having a light axis, an electrical axis along a length of the quartz bar, and a mechanical axis that are perpendicular to one another; obtaining a cutting plane by rotating about the electric axis through a first angle of about 35° to about 36° in a direction from the light axis toward the mechanical axis, and thereafter, rotating about the light axis through a second angle of about 10° to about 12° in a direction from the electrical axis to the mechanical axis; and cutting the quartz bar along the cutting plane to obtain a quartz crystal of the quartz crystal resonator.
In yet another aspect of the present disclosure, a method of making a quartz crystal resonator is provided. The method includes: obtaining a quartz bar, the quartz bar having a light axis, an electrical axis along a length of the quartz bar, and a mechanical axis that are perpendicular to one another; rotating the quartz bar to orient the quartz bar at an AT-cut angle; based on the AT-cut angle, obtaining a cutting plane by rotating about the light axis through an angle in a direction from the electrical axis toward the mechanical axis; and cutting the quartz bar along the cutting plane to obtain a quartz crystal of the quartz crystal resonator; and wherein the angle is determined such that the obtained quartz crystal has a vibration frequency deviation within a range from −20 parts per million (ppm) to +20 ppm over an operating temperature range from about −40° C. to about 125° C.
Various aspects of the present disclosure may be best understood from the following description and accompanying drawings. It should be noted that, in accordance with standard working practice in the related art, various features in the drawings are not drawn to scale. In fact, the dimensions of some features may be enlarged or reduced on purpose for clarity of description.
The technical solutions and beneficial effects of the present application will be made apparent through the detailed description of embodiments of the present application in conjunction with the accompanying drawings, in which:
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the embodiments and are not necessarily drawn to scale.
The making and using of embodiments of this disclosure are discussed in detail below. It should be appreciated, however, that the concepts disclosed herein can be embodied in a wide variety of specific contexts, and that the specific embodiments discussed herein are merely illustrative and do not serve to limit the scope of the claims. Further, it should be understood that various changes, substitutions and alterations can be made herein without departing from the spirit and scope of this disclosure as defined by the appended claims.
The following provides various embodiments or examples for implementing different features of the present disclosure. Specific examples of components and configurations are described below to simplify description of the present disclosure. Certainly, these are examples only and are not intended to be limiting. For example, in the following description, a first member being formed above a second member or the first member being formed on the second member may include an embodiment where the first member and the second member are in direct contact, and also an embodiment where an additional member is formed between the first member and the second member such that the first member and the second member may not be in direct contact. Additionally, the present disclosure may repeat component symbols and/or letters in various examples. Such repetition is for simplicity and clarity, and does not in itself represent a relationship between the various embodiments and/or configurations discussed.
In addition, for ease of description, spatially relative terms such as “under”, “beneath”, “below”, “above”, “on” and the like may be used herein to describe a relationship of a component or member with another component(s) or member(s), as shown in the drawings. Spatially relative terms are intended to encompass different orientations of a device in use or operation in addition to the orientations depicted in the drawings. The device may be oriented in other ways (rotated 90 degrees or at other orientations), and the spatially relative terms used herein may be interpreted in a corresponding way similarly.
As used herein, terms such as “first”, “second”, “third”, and so on, may be used to describe various components, members, regions, layers, and/or sections, and these components, members, regions, layers, and/or sections should not be limited by these terms. These terms may merely be used to distinguish one component, member, region, layer or section from another. The terms “first”, “second”, “third”, and so on, when used herein, do not imply a sequence or order unless clearly indicated by the context.
A quartz crystal resonator is an electronic component that uses the piezoelectric effect of quartz crystal to generate a high-precision vibration frequency. In particular, the quartz crystal itself is a passive component that can be manufactured as a so-called resonator. If the quartz crystal is combined with an integrated circuit designed with an oscillation circuit, it can be packaged as an active electronic component called crystal oscillator (XO), and specific products may include, based on their usage and specifications, a voltage-controlled crystal oscillator (VCXO), a temperature-compensated/voltage-controlled temperature-compensated crystal oscillator (TCXO/VCTCXO), a constant temperature control crystal oscillator (OCXO), and so on. Many electronic circuits need oscillators to synchronize activity or provide a frequency reference. For example, a microcontroller's frequency signal is used to control movement of data to and from memory, execution of instructions, and external communication speeds; and in a radio system, an oscillator can provide a fixed frequency for communications of a transmitter and a receiver.
A quartz crystal is a single crystal of silicon dioxide, and the quartz crystal (or quartz chip) required in industry can be cut from a quartz bar. The commonly used quartz bar is a perfect single-crystal α-quartz made through artificial growth. Because the quartz crystal is anisotropic, when the quartz crystal is cut along different directions, different geometric slices may be obtained, and the different geometric slices have different oscillation modes. An advantage of the quartz crystal is that when temperature changes, the elastic coefficient and size that affect the oscillation frequency change slightly, and thus the frequency characteristic presented is relatively stable. In strict occasions that require high precision and stability, the temperature of the quartz crystal will be monitored in order to correct errors at any time. If a smaller error is required, in some cases, the quartz crystal or component including the quartz crystal will be placed in an incubator and a vibration-absorbing container to prevent interferences caused by external temperature and vibration.
Performance indicators of a quartz crystal resonator include accuracy, stability, power consumption, and so on. Among them, the first two are very important for communication protocols and time records, and the accuracy and stability of a quartz crystal resonator are closely related to properties of the quartz crystal that the quartz crystal resonator includes. As mentioned earlier, the oscillation of the quartz crystal is from the piezoelectric effect, that is, when a pressure is applied to the quartz crystal, a voltage will be generated inside the quartz crystal (positive piezoelectric effect), and when a voltage is applied, the inside of the quartz crystal will be deformed (reverse piezoelectric effect). A quartz crystal with feedback can serve as a highly accurate and stable resonator, and its natural frequency depends on the size and cutting manner of the crystal.
In commonly used quartz crystal resonators, a quartz bar is usually cut into thin slices by means of AT-cut, which are used as the quartz crystals required by quartz crystal resonators. In a quartz crystal model, as shown in
The above-mentioned AT-cut, as shown in
Embodiments of the present disclosure provide, based on the consideration of the vibration frequency deviation of the quartz crystal in a specific operating temperature range, a novel quartz bar cutting method, to obtain a quartz crystal that can maintain a relatively stable vibration frequency deviation in a large operating temperature range, especially in an extreme working environment having high temperature and low temperature, and the quartz crystal may be used to manufacture a high-quality quartz crystal resonator with good environmental tolerance. The vibration frequency deviation indicates that the actual resonance frequency of the quartz crystal deviates from the original target frequency of the quartz crystal due to temperature changes, and the degree of deviation is usually in a unit of parts per million (ppm), e.g., 0 ppm indicates no deviation. In the present disclosure, the permissible deviation range of the quartz crystal vibration frequency for precision components is set to be ±20 ppm.
In some embodiments of the present disclosure, as shown in
The inflection point refers to the point where a curve changes from convex to concave or from concave to convex. It can also be determined by the tangent of the curve passing through the curve at the point, and its technical meaning is that the quartz crystal has the most stable vibrational pattern at the corresponding temperature. As shown from the relationship between temperature and vibration frequency deviation in
The above-mentioned temperature range is related to a selectable range of cutting angles of the quartz crystal. In some embodiments, the first angle θ is between about 35 degrees and about 36 degrees; in some embodiments, the first angle θ is about 35 degrees 15 minutes; in some embodiments, the first angle θ is about 35 degrees 25 minutes; and in some embodiments, the first angle θ is the same as the cutting angle typically selected for the AT-cut (see the AT-cut quartz crystal 90 as shown in
As for the range of the second angle φ, in some embodiments, the second angle φ is between about 10 degrees and about 12 degrees; in some embodiments, the second angle φ is about 10 degrees; in some embodiments, the second angle φ is about 12 degrees; and in some embodiments, the selection of the second angle φ may be based on the consideration that the cut quartz crystal can maintain the vibration frequency deviation within an acceptable range (e.g., within ±20 ppm) in a wide operating temperature range (for example, from about −40 degrees Celsius to about 125° C.).
In particular, the quartz crystal resonator of embodiments of the present disclosure uses a quartz crystal having better tolerance to temperature changes, so that the quartz crystal resonator has a certain level of precision performance in either a cold or hot working environment. Taking automotive electronics as an example, with reference to the automotive specification verification standards formulated by the international Automotive Electronics Council (AEC), the temperature range from about −40° C. to about 125° C. belongs to the discrete semiconductor operating temperature range specified by the AEC-Q101 standard, which is an example of a relatively wide operating temperature range defined in industry. Considering that the quartz crystal obtained through the fixed quartz bar cutting method does not have the characteristics of maintaining a good vibration frequency deviation over a wide operating temperature range, the quartz crystal resonator of the present disclosure exhibiting a small vibration frequency deviation over the above operating temperature range provides a significant advantage in applications.
Regarding the operations of a quartz crystal in the operating temperature range, for example, as shown in the graph (comprehensive) of the relationship between temperature and vibration frequency deviation in
In view of the above description that the characteristics of the quartz crystals obtained by the AT-cut do not meet the requirements of the vibration frequency deviation in some operating temperature ranges, embodiments of the present disclosure use the second angle φ as a correction angle (in other words, the AT-cut can be regarded as a case where the second angle φ is 0 degree), and utilize the characteristics of the quartz crystal obtained by further rotating an angle at which the quartz bar is to be cut, in order for the quartz crystal to meet the requirement of the vibration frequency deviation in a wide operating temperature range.
As mentioned above, in some embodiments of the present disclosure, the second angle φ is between about 10 degrees and about 12 degrees. Taking the second angle φ being 10 degrees as an example, the first angle θ as disclosed above may be formed between the major face 20A of the quartz crystal and the light axis (Z) by rotating about the electric axis, the second angle φ of 10 degrees may then be formed between the major face 20A and the electric axis (X) by rotating about the light axis, and thereafter, the quartz bar is cut. The quartz crystal obtained in this way has a relationship between temperature and vibration frequency deviation as shown in
If the second angle φ is adjusted to be 12°, as shown in
The above-described embodiments of the present disclosure use a difference of two degrees as an exemplary example, however, the second angle φ is not limited to be only about 10 degrees or about 12 degrees. When the second angle φ is within the range from about 10 degrees to about 12 degrees, the cut quartz crystal is able to have a vibration frequency deviation within ±20 ppm in the operating temperature range between about −40° C. and about 125° C., and the inflection point of the vibration frequency deviation of the quartz crystal falls within the range from about 30° C. to about 35° C. or the range from about 40° C. to about 45° C., i.e., the inflection point of the vibration frequency deviation varies in these temperature ranges with a small adjustment of the second angle φ.
In some comparative embodiments, as shown in
For example, first, as shown in
Second, as shown in
Third, as shown in
Then, as shown in
In view of above, the embodiments of the present disclosure provide a quartz bar, and the cutting angle obtained by double rotation enables a quartz crystal that is cut from the quartz bar at this cutting angle to maintain a better vibration frequency deviation in a larger operating temperature range, which enables a quartz crystal resonator utilizing the quartz crystal to comply with stricter industrial standards and be suitable for operating environments with more severe temperature changes.
In some embodiments of the present disclosure, a method is also provided for making a quartz crystal resonator. As shown in
In some embodiments, the cut quartz crystal may be included in a structure of a quartz crystal resonator through a packaging process. In addition, the oscillation frequency of the quartz crystal is related to the thickness of the quartz crystal, for example, as the oscillation frequency increases, the thickness of the chip will be correspondingly thinner. Therefore, in some embodiments, the method for making the quartz crystal resonator may include a step of: determining a cutting thickness for cutting the quartz bar based on a target frequency of the quartz crystal resonator, to obtain a quartz crystal with a required cutting thickness.
Comparing some embodiments of the present disclosure with quartz crystals obtained by AT-cut (the second angle φ is 0°), as shown in
The foregoing provides features of certain embodiments of the present disclosure for those ordinarily skilled in the art to more fully understand the various aspects of the present disclosure. Those of ordinary skill in the art of the present disclosure should understand that they can readily design or modify other processes and structures based on the present disclosure to achieve the same purposes and/or achieve the same advantages as the embodiments herein. Those of ordinary skill in the art of the present disclosure should also understand that these equivalent embodiments still belong to the spirit and scope of the present disclosure, and various alterations, substitutions and changes can be made without departing from the spirit and scope of the present disclosure.
Moreover, the scope of the disclosure is not intended to be limited to the particular embodiments described herein, as one of ordinary skill in the art will readily appreciate from this disclosure that processes, machines, manufacture, compositions of matter, means, methods, or steps, presently existing or later to be developed, may perform substantially the same function or achieve substantially the same result as the corresponding embodiments described herein.
Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202211657114.4 | Dec 2022 | CN | national |
