阅读说明：本技术 一种叉指换能器 (interdigital transducer ) 是由 张树民 王国浩 汪泉 其他发明人请求不公开姓名 于 2019-09-09 设计创作，主要内容包括：本发明提供一种叉指换能器,包括：压电基板；设置在压电基板上的第一汇流电极；设置在压电基板上的第二汇流电极,且与所述第一汇流电极相对间隔设置；呈周期设置的多个第一叉指电极,该叉指电极自第一汇流电极向第二汇流电极的方向延伸；呈周期设置的多个第二叉指电极,该叉指电极自第二汇流电极向第一汇流电极的方向延伸；第一叉指电极和第二叉指电极交替间隔设置,并且,在沿其长度方向上,第一叉指电极和第二叉指电极的宽度呈预设变化。本发明提供的叉指换能器通过第一叉指电极和第二叉指电极的宽度呈预设变化,进而改变叉指电极的金属化比值,以调节各部分的SAW速度,达到抑制温度补偿声表面波器件中的横向模式。(the present invention provides an interdigital transducer, including: a piezoelectric substrate; a first bus electrode provided on the piezoelectric substrate; the second bus electrode is arranged on the piezoelectric substrate and is opposite to the first bus electrode at an interval; a plurality of first interdigital electrodes arranged periodically, the interdigital electrodes extending from the first bus electrode in a direction toward the second bus electrode; a plurality of second interdigital electrodes arranged periodically, the interdigital electrodes extending from the second bus electrodes in a direction toward the first bus electrodes; the first interdigital electrode and the second interdigital electrode are alternately arranged at intervals, and the width of the first interdigital electrode and the width of the second interdigital electrode are preset in the length direction. The interdigital transducer provided by the invention changes the metallization ratio of the interdigital electrode by preset change of the widths of the first interdigital electrode and the second interdigital electrode so as to adjust the SAW velocity of each part and achieve the purpose of inhibiting the transverse mode in the temperature compensation surface acoustic wave device.)

1. an interdigital transducer, comprising:

A piezoelectric substrate;

A first bus electrode provided on the piezoelectric substrate;

The second bus electrode is arranged on the piezoelectric substrate and is opposite to the first bus electrode at an interval;

A plurality of first interdigital electrodes arranged in a cycle, the first interdigital electrodes extending from the first bus electrode in a direction toward the second bus electrode;

A plurality of second interdigital electrodes arranged in a cycle, the second interdigital electrodes extending from the second bus electrode in a direction toward the first bus electrode;

The first interdigital electrode and the second interdigital electrode are alternately arranged at intervals, and the widths of the first interdigital electrode and the second interdigital electrode are in preset variation along the length direction of the first interdigital electrode and the second interdigital electrode.

2. The interdigital transducer of claim 1, wherein the first and second interdigital electrodes have a width that is smaller and larger.

3. The interdigital transducer of claim 1, wherein the widths of the first and second interdigital electrodes become larger and smaller.

4. The interdigital transducer of claim 1, wherein the widths of the first and second interdigital electrodes are periodically increased and then decreased.

5. The interdigital transducer of claim 1, wherein the widths of the first and second interdigital electrodes are periodically decreased and then increased.

6. The interdigital transducer according to any one of claims 1 to 5, wherein the metallization ratio of the first interdigital electrode and the second interdigital electrode is in a range of 0.2 to 0.8;

The metallization ratio of the first interdigital electrode is the ratio of the width of the first interdigital electrode to the sum of the width and the gap between the adjacent second interdigital electrodes;

the metallization ratio of the second interdigital electrode is the ratio of the width of the second interdigital electrode to the sum of the width and the gap between adjacent first interdigital electrodes.

7. the interdigital transducer according to any one of claims 1 to 5, wherein a length of the first interdigital electrode having a preset variation in width along the length direction of the first interdigital electrode is 1/3 to 2/3 of the length of the first interdigital electrode; and/or the presence of a gas in the gas,

In the length direction of the second interdigital electrode, the length of the second interdigital electrode with preset variation in width is 1/3-2/3 of the length of the second interdigital electrode.

8. The interdigital transducer of claim 7, wherein the region where the width of the first interdigital electrode is changed by a predetermined amount is at a central region in a length direction thereof; and/or the presence of a gas in the gas,

The area where the width of the second interdigital electrode is changed in a preset mode is the central area of the second interdigital electrode in the length direction.

9. The interdigital transducer according to any one of claims 1 to 5, wherein the first interdigital electrode is an aluminum interdigital electrode or a copper interdigital electrode; and/or the presence of a gas in the gas,

the second interdigital electrode is an aluminum interdigital electrode or a copper interdigital electrode.

10. the interdigital transducer according to any one of claims 1 to 5, wherein the piezoelectric substrate is any one of a lithium tantalate piezoelectric substrate, a lithium niobate piezoelectric substrate, and a quartz substrate.

Technical Field

the invention relates to a microelectronic device, in particular to an interdigital transducer.

background

An important design consideration of a Surface Acoustic Wave Temperature compensation filter (TC-SAW) is to suppress a transverse propagation mode, because an Interdigital Transducer (IDT) aperture of a Surface Acoustic Wave device is limited, diffraction and beam deflection exist in the Surface Acoustic Wave during propagation, and according to a plane angular spectrum theory, a diffraction integral field of the Surface Acoustic Wave is as follows:

(Wang Cheng Fu Shu, science publishers, 1990, pages 338-455)

Wherein γ is the anisotropy constant of the substrate and has

from the above equation, if the anisotropy constant γ of the surface acoustic wave on the substrate is-1, the acoustic field will keep the aperture cross-sectional shape unchanged in the propagation direction, i.e., there is no transverse propagation mode. However, none of the existing materials has an anisotropy constant of-1, and particularly for temperature compensated surface acoustic wave devices, there are very severe transverse modes. The conventional method for inhibiting the transverse mode in the TC-SAW is to arrange a piston structure at two ends of an electrode, namely, arrange thickened or thickened small sections at two ends of the electrode, wherein the tail end is in a T-shaped structure, an incident SAW and a reflection SAW are mutually counteracted to limit the energy of the SAW in a middle IDT waveguide and limit the SAW from propagating to the outer side of the IDT, the mode is similar to a total reflection optical fiber, but a square block for overcompensation is added at the tail end of an interdigital electrode, and the solidified geometrical structure of the mode plays a role in inhibiting the transverse propagation in a temperature compensation surface acoustic wave device to be limited, so that the application range of the surface acoustic wave device is limited to a certain extent. Therefore, it is necessary to develop an interdigital transducer that suppresses a transverse mode in a temperature-compensated surface acoustic wave device by adjusting a certain component characteristic thereof without changing the overall structure.

Disclosure of Invention

the present invention is directed to solve at least one of the problems of the prior art and to provide an interdigital transducer.

The present invention mainly provides an interdigital transducer, which includes:

A piezoelectric substrate;

A first bus electrode provided on the piezoelectric substrate;

the second bus electrode is arranged on the piezoelectric substrate and is opposite to the first bus electrode at an interval;

A plurality of first interdigital electrodes arranged in a cycle, the first interdigital electrodes extending from the first bus electrode in a direction toward the second bus electrode;

A plurality of second interdigital electrodes arranged in a cycle, the second interdigital electrodes extending from the second bus electrode in a direction toward the first bus electrode;

The first interdigital electrode and the second interdigital electrode are alternately arranged at intervals, and the widths of the first interdigital electrode and the second interdigital electrode are in preset variation along the length direction of the first interdigital electrode and the second interdigital electrode.

Optionally, the widths of the first interdigital electrode and the second interdigital electrode are first reduced and then increased.

Optionally, the widths of the first interdigital electrode and the second interdigital electrode are increased and then decreased.

Optionally, the widths of the first interdigital electrode and the second interdigital electrode are periodically increased and then decreased.

optionally, the widths of the first interdigital electrode and the second interdigital electrode are periodically decreased and then increased.

optionally, the metallization ratio of the first interdigital electrode and the metallization ratio of the second interdigital electrode are both 0.2-0.8;

The metallization ratio of the first interdigital electrode is the ratio of the width of the first interdigital electrode to the sum of the width and the gap between the adjacent second interdigital electrodes;

the metallization ratio of the second interdigital electrode is the ratio of the width of the second interdigital electrode to the sum of the width and the gap between adjacent first interdigital electrodes.

Optionally, in the length direction of the first interdigital electrode, the length of the width of the first interdigital electrode which changes in a preset manner is 1/3-2/3 of the length of the first interdigital electrode; and/or the presence of a gas in the gas,

In the length direction of the second interdigital electrode, the length of the second interdigital electrode with preset variation in width is 1/3-2/3 of the length of the second interdigital electrode.

Optionally, the area where the width of the first interdigital electrode changes in a preset manner is a central area in the length direction of the first interdigital electrode; and/or the presence of a gas in the gas,

The area where the width of the second interdigital electrode is changed in a preset mode is the central area of the second interdigital electrode in the length direction.

optionally, the first interdigital electrode is an aluminum interdigital electrode or a copper interdigital electrode; and/or the presence of a gas in the gas,

The second interdigital electrode is an aluminum interdigital electrode or a copper interdigital electrode.

Optionally, the piezoelectric substrate is any one of a lithium tantalate piezoelectric substrate, a lithium niobate piezoelectric substrate, and a quartz substrate.

The invention provides an interdigital transducer, which changes the metallization ratio of each interdigital electrode by changing the preset width of a first interdigital electrode and a second interdigital electrode to adjust the SAW speed of each part so as to inhibit the transverse mode in a temperature compensation surface acoustic wave device. Under the condition of not changing the integral structure and process conditions of the interdigital transducer, the invention only designs that all interdigital electrodes have different widths along the length direction so as to lead the metallization ranges of the interdigital electrodes to be different and lead the metallization ranges of the interdigital electrodes to change the range for inhibiting the transverse mode, and the transverse propagation speed of each interdigital electrode is slower along with the larger metallization ratio of each interdigital electrode, the diffraction and the beam inclination are reduced in the propagation process, thereby leading the anisotropy constant gamma of the surface acoustic wave to be-1 and leading the transverse mode in the surface acoustic wave device to be almost completely inhibited.

Drawings

Fig. 1 is a schematic structural view of an interdigital transducer in the present invention.

Detailed Description

In order to make the technical solutions of the present invention better understood, the present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.

as shown in fig. 1, the present invention provides an interdigital transducer comprising: the piezoelectric element includes a piezoelectric substrate 100, a first bus electrode 101 and a second bus electrode 102 provided on the piezoelectric substrate 100, the second bus electrode 102 being provided at an interval opposite to the first bus electrode 101, and a plurality of first interdigital electrodes 103 provided in a cycle, the first interdigital electrodes 103 extending from the first bus electrode 101 in a direction of the second bus electrode 102, and a plurality of second interdigital electrodes 104 provided in a cycle, the second interdigital electrodes extending from the second bus electrode 102 in a direction of the first bus electrode 101. The first interdigital electrode 103 and the second interdigital electrode 104 are alternately arranged at intervals, and the widths of the first interdigital electrode 103 and the second interdigital electrode 104 are preset and changed along the length direction of the first interdigital electrode 103 and the second interdigital electrode 104.

According to the interdigital transducer provided by the embodiment, the preset widths of the first interdigital electrode and the second interdigital electrode are changed to a certain extent, so that the metallization ratio of each interdigital electrode is changed, the SAW speed of each part is adjusted, and the purpose of inhibiting the transverse mode in the temperature compensation surface acoustic wave device is achieved. Under the condition of not changing the integral structure and process conditions of the interdigital transducer, the invention only designs that all interdigital electrodes have different widths along the length direction so as to lead the metallization ranges of the interdigital electrodes to be different and lead the metallization ranges of the interdigital electrodes to change the range for inhibiting the transverse mode, and the transverse propagation speed of each interdigital electrode is slower along with the larger metallization ratio of each interdigital electrode, the diffraction and the beam inclination are reduced in the propagation process, thereby leading the anisotropy constant gamma of the surface acoustic wave to be-1 and leading the transverse mode in the surface acoustic wave device to be almost completely inhibited.

Specifically, as shown in fig. 1, in the length direction of the first interdigital electrode 103 and the second interdigital electrode 104, the widths of the first interdigital electrode 103 and the second interdigital electrode 104 become smaller and larger, and the first interdigital electrode 103 and the second interdigital electrode 104 take a dumbbell shape with a thin middle and thick two ends.

It should be noted that the shapes and sizes of the first interdigital electrode 103 and the second interdigital electrode 104 are not specifically limited, and may also be spindle-shaped like thick middle and thin two ends, that is, along the length direction of the first interdigital electrode 103 and the second interdigital electrode 104, the widths of the first interdigital electrode 103 and the second interdigital electrode 104 become larger first and then smaller. In addition, the shape may be similar to a shape of a sugarcoated haw with a thick interval, that is, the widths of the first interdigital electrode 103 and the second interdigital electrode 104 may be periodically increased and then decreased, or the widths of the first interdigital electrode 103 and the second interdigital electrode 104 may be periodically decreased and then increased. Of course, those skilled in the art can select the interdigital electrodes with other shapes according to the actual requirement.

In order to suppress a transverse mode in the surface acoustic wave device, the metallization ratio of the first interdigital electrode 103 and the second interdigital electrode 104 is in a range of 0.2-0.8; wherein the metallization ratio of the first interdigital electrode 103 is the ratio (a/b) of the width of the first interdigital electrode 103 to the sum of the width and the gap between the adjacent second interdigital electrode 104, as shown in fig. 1, the width of the first interdigital electrode 103 is the length denoted by a in fig. 1, and the width of the first interdigital electrode 103 and the sum of the width and the gap between the adjacent second interdigital electrode 104 are the length denoted by b in fig. 1. Similarly, the metallization ratio of the second interdigital electrode 103 is the ratio of the width of the second interdigital electrode 104 to the sum of the width and the gap between adjacent first interdigital electrodes 103, as shown in fig. 1, the width of the second interdigital electrode 104 is denoted by c in fig. 1, the sum of the width of the first interdigital electrode 103 and the gap between the width and the adjacent second interdigital electrode 104 is denoted by d in fig. 1, and the width a of the first interdigital electrode 103 is equal to the width c of the second interdigital electrode 104, and the width a and the gap b between the adjacent second interdigital electrodes 104 are equal to the width c and the gap d between the adjacent first interdigital electrodes 103.

That is, in the embodiment, as the width of each interdigital electrode changes along the length direction of the first interdigital electrode 103 and the second interdigital electrode 104, the corresponding metallization values (a/b, c/d) also change, and the change can flexibly adjust the SAW velocity of each part, so as to suppress the transverse mode in the temperature compensated surface acoustic wave device.

It should be noted that, for the change starting point of the metallization value of each interdigital electrode, there is no fixed setting, and the length range and the position of the preset change of the width of the first interdigital electrode 103 can be adjusted to adjust the metallization value of the first interdigital electrode 103 along the length direction thereof (y direction shown in fig. 1), and the length range and the position of the preset change of the width of the second interdigital electrode 104 can be adjusted to adjust the metallization value of the second interdigital electrode 104 along the length direction thereof (y direction shown in fig. 1), thereby adjusting the SAW speed of each part.

specifically, as shown in fig. 1, the length of the first interdigital electrode 103 with a preset variation in width along the length direction of the first interdigital electrode 103 is 1/3 to 2/3 of the length of the first interdigital electrode 103. In addition, in the length direction along the second interdigital electrode 104, the length of the second interdigital electrode 104 with preset variation in width is 1/3-2/3 of the length of the second interdigital electrode 104.

note that the length of the first interdigital electrode 103 is extended from the end of the first interdigital electrode 103 to the side of the first bus bar electrode 101 to a position flush with the end of the second interdigital electrode 104, and of course, the length of the second interdigital electrode 104 is the same as the length of the first interdigital electrode 103.

specifically, as shown in fig. 1, the region where the width of the first interdigital electrode 103 is changed by a preset amount is the central region in the length direction thereof, and the region where the width of the second interdigital electrode 104 is changed by a preset amount is the central region in the length direction thereof. It should be noted that the position of the preset changing region of the widths of the first interdigital electrode 103 and the second interdigital electrode 104 is not specifically limited, and may be a side close to the first bus bar electrode 101 or a side close to the second bus bar electrode 102 in the length direction, and of course, a person skilled in the art may set the preset changing region position of each interdigital electrode at any position of each interdigital electrode along the length direction according to actual needs.

it should be noted that the first interdigital electrode 103 is an aluminum interdigital electrode or a copper interdigital electrode; and/or the second interdigital electrode 104 is an aluminum interdigital electrode or a copper interdigital electrode. The piezoelectric substrate 100 is preferably any one of a lithium tantalate piezoelectric substrate, a lithium niobate piezoelectric substrate, and a quartz substrate.

Compared with the prior art, the interdigital transducer provided by the invention has the main advantages that the preset widths of the first interdigital electrode and the second interdigital electrode are changed to a certain extent, so that the metallization ratio of each interdigital electrode is changed, the SAW speed of each part is adjusted, and the purpose of inhibiting the transverse mode in the temperature compensation surface acoustic wave device is achieved. Under the condition of not changing the integral structure and process conditions of the interdigital transducer, the invention only designs that all interdigital electrodes have different widths along the length direction, so that the metallization ranges of the interdigital electrodes are different, and the range of inhibiting the transverse mode is changed, and the transverse propagation speed is slower along with the larger metallization ratio of all the interdigital electrodes, the diffraction and beam inclination are reduced in the propagation process, so that the anisotropy constant gamma of the surface acoustic wave is-1, and the transverse mode in the surface acoustic wave device is almost completely inhibited. The interdigital transducer simplifies the structure of the device and the complexity of the process, and avoids the damage of the interdigital electrode caused by the conventional process and the influence on the performance of the surface acoustic wave device caused by the damage.

It is to be understood that the above embodiments are merely exemplary embodiments employed for the purpose of illustrating the present invention, and the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.