KR20030039502A - Dual surface acoustic wave element - Google Patents

Abstract

PURPOSE: A dual surface acoustic wave device is provided to protecting the deterioration of each of the cavities by preventing the resonance frequency generated from a first and a second resonant part from interfering each other. CONSTITUTION: A dual surface acoustic wave device(100) includes a substrate(19) in the form of plate having a piezoelectric characteristics, a plurality of interdigital transducer(IDT)(12) formed on top of the substrate(19), a first resonant part(10) formed thereon a pair of reflectors(15) at both end sides of the IDT(12), a plurality of IDTs(12) formed on a sound track similar to the first resonant part(10) and a second resonant part(20) provided with a pair of reflectors(15) formed both side ends of the IDT(12). The dual surface acoustic wave device further includes an elastic wave traveling prevention groove(17) formed on top of the substrate(19) between the first resonant part(10) and the second resonant part(20) at a predetermined depth.

Description

Dual surface acoustic wave element

The present invention relates to a dual surface acoustic wave device, and more particularly, to a dual surface acoustic device in which two surface acoustic wave devices are formed in one acoustic track so that surface acoustic waves by each device do not interfere with each other. .

Generally, surface acoustic wave devices use waves that propagate on the surface of an elastic solid for electronic signal processing. The surface acoustic wave device has a characteristic of converting and processing electromagnetic waves traveling at a speed of light into acoustic waves traveling at a speed smaller than that of light. This feature enables some complex signal processing functions to be implemented in spaces significantly smaller than those required in traditional circuit designs. Thus, surface acoustic wave devices designed to handle complex signal processing functions can provide significant cost and size advantages over other technologies. Such surface acoustic wave device technology is increasing in applications such as filters, resonators, oscillators, delay lines and other similar devices.

The surface acoustic wave device is usually implemented on a substrate having piezoelectric properties and uses an IDT disposed on the surface of the substrate to generate and detect sound waves (hereinafter referred to as surface acoustic waves). The geometry (width, pitch, number) of IDT on the substrate plays an important role in the frequency response and signal processing characteristics of the surface acoustic wave elements.

In addition, a plurality of such surface acoustic wave elements may be formed to operate independently on one substrate. For example, as shown in FIG. 1, it may be formed in a dual type, and the conventional dual type surface elastic element 100 ′ will be described with reference to the following.

As shown, a substantially plate-shaped substrate 19 'having piezoelectric properties is provided. One side of the substrate 19 ′ is formed with electrode lines 11 ′ extending horizontally at a predetermined distance from each other, and a plurality of IDTs 12 ′ extend from the electrode lines 11 ′. It is formed. In addition, reflectors 15 'are formed at both sides of the electrode line 11' such that the center frequency generated from the substrate 19 'and the IDT 12' can be resonated (or reflected). The reflectors 15 'are usually spaced apart by an integer multiple of one-half wavelength [lambda]. In addition, lines 13 'are connected to the electrode line 11', respectively, and are connected to an external electric signal source 14 '. The structure may be defined as a first resonator 10 ', and another second resonator 20' may be formed on an acoustic track such as the first resonator 10 '. That is, the dual surface elastic element 100 'can be configured. The conventional surface acoustic wave device 100 'has a characteristic that the center frequencies of the first resonator 10' and the second resonator 20 'may be operated differently from each other.

That is, by forming different widths, pitches or spacings of the IDT 12 'and / or the reflector 15' formed in the first resonator 10 'and the second resonator 20', the centers are different from each other. Two elastic elements 100 'having a frequency may be provided in one substrate 19'.

An example of the operation of the first resonator 10 'or the second resonator 20' is known from the external electrical signal source 14 'to each electrode line 11' along the line 13 '. When a predetermined electrical signal is applied, the predetermined electromagnetic wave signal is converted into a surface acoustic wave signal by the interaction of the IDT 12 'and the substrate 19'. This surface acoustic wave signal eventually forms a standing wave by the reflector 15 ', and thus, the first resonator 10' and the second resonator 20 'are formed by oscillator or filter coalescence. It can be used as an element 100 'having a high Q (a sensitivity of resonance, the higher the Q value, the stronger the ability to separate radio waves).

However, the conventional dual surface elastic element 100 ′ is formed with the first resonator 10 ′ and the second resonator 20 ′ on the same sound track, so that the first resonator 10 ′ and Surface acoustic waves from the second resonator 20 'have a disadvantage of mutual interference. Although the reflector 15 'is formed in each of the resonators, a small surface acoustic wave affects the other resonators adjacent to the other resonators, which causes the characteristics of each resonator to deteriorate. There are disadvantages.

Accordingly, the present invention has been made to solve the above-mentioned conventional problems, and when two surface acoustic wave elements are formed in one acoustic track, a dual surface elastic element which prevents surface acoustic waves by each element from interfering with each other. To provide.

1 is a plan view showing a conventional dual surface acoustic wave device.

FIG. 2A is a plan view showing a dual surface acoustic wave device according to the present invention, and FIG. 2B is a sectional view taken along line II of FIG. 2A.

-Description of the main symbols in the drawings-

100; Surface acoustic wave device according to the present invention

10; First resonator 20; 2nd resonance part

11; Electrode line

12; Interdigital Transducer (IDT)

13; Line 14; External electrical signal source

15; Reflector 17; Seismic Progression Groove

19; Substrate

In order to achieve the above object, the present invention provides a substantially plate-shaped substrate having piezoelectric properties, and a plurality of IDTs are formed on the upper surface of the substrate, and reflectors are formed on both sides of the IDT. A surface acoustic wave device comprising a first resonator and a second resonator having a plurality of IDTs formed on the same sound track as the first resonator, and reflectors formed on both sides of the IDT. A seismic wave progress prevention groove having a predetermined depth is formed on the upper substrate between the second resonators.

Here, the depth of the elastic wave traveling prevention groove is preferably formed deeper than the wavelength (λ) of the resonance frequency generated in the first resonator and the second resonator.

According to the dual surface elastic element according to the present invention as described above, the surface of the acoustic wave propagation preventing grooves having a depth larger than the wavelength of the resonance frequency generated in the first resonance portion and the second resonance portion is formed, the surface generated in each resonance portion It is possible to prevent the interference phenomenon caused by the acoustic wave.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings such that those skilled in the art can easily implement the present invention.

FIG. 2A is a plan view showing a dual surface acoustic wave device 100 according to the present invention, and FIG. 2B is a sectional view taken along line II of FIG. 2A.

A substantially plate-shaped substratum 19 having piezoelectric properties is provided. The substrates 19 may be formed by using any one of quartz, piezoelectric, LaTiO ₃ , LaNbO ₃ , ZnO, or equivalent thereof having piezoelectric properties as is well known.

On one side of the substrate 19, electrode lines 11 extending horizontally are spaced apart from each other by a predetermined distance, and a plurality of IDTs 12 are formed from the electrode lines 11 in the up and down directions. It is extended.

The electrode line 11 and the IDT 12 may be formed by any one of gold (Au), silver (Ag), copper (Cu), or an equivalent thereof.

In addition, a plurality of reflectors 15 are formed at both sides of the electrode line 11 so that the center frequency generated from the substrate 19 and the IDT 12 can be resonated (or reflected). The reflectors 15 are spaced apart from each other by an integer multiple of 1/2 wavelength.

As described above, the reflector 15 may be formed of a conductive thin film or an insulating thin film.

In addition, lines 13 are respectively connected to the electrode line 11 to an external electric signal source 14.

Such a structure may be defined as the first resonator 10 as described above, and another second resonator 20 is formed on an acoustic track such as the first resonator 10. Since the configuration of the second resonator 20 has the same configuration as that of the first resonator 10, the same reference numerals are used, and further description thereof will be omitted.

Here, an elastic wave propagation preventing groove 17 having a predetermined depth is formed on an upper surface of the substrate 19 between the first resonator 10 and the second resonator 20. That is, the elastic wave propagation preventing groove 17 having a predetermined depth is further formed in a direction parallel to each of the reflectors 15 of the first resonator 10 and the second resonator 20. The elastic wave propagation preventing groove 17 can be formed by a conventional etching. That is, after the photoresist is formed in a region other than the region where the acoustic wave progression preventing groove 17 is to be formed, a sub-level of a predetermined depth is performed using a conventional wet / chemical etching method or dry etching method. Remove straight 19.

In addition, the depth of the elastic wave propagation preventing groove 17 is formed deeper than the wavelength? Of the resonance frequency generated in the first resonator 10 and the second resonator 20. That is, surface acoustic waves generated or transmitted in the first resonator unit 10 and the second resonator unit 20 travel along the surface of the substrate 19, and the traveling depth is greater than or equal to the wavelength of the surface acoustic wave. Because it is not delivered to the depth to.

Therefore, the surface acoustic waves generated and transmitted in the first resonator 10 and the second resonator 20, respectively, do not interfere with each other, so that the first resonator 10 and the second resonator 20 The properties will appear as the original design features.

As described above, although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto, and various modified embodiments may be possible without departing from the scope and spirit of the present invention.

Therefore, according to the dual surface elastic element according to the present invention, the resonance frequencies generated in the first resonator unit and the second resonator unit do not interfere with each other, so that the characteristics of each resonator unit do not deteriorate.

Claims (2)

A substantially resonant plate having a piezoelectric property, a plurality of interdigital transducers (IDTs) formed on an upper surface of the substrates, and reflectors formed on both sides of the IDTs; In the surface acoustic wave device comprising a plurality of IDTs are formed on the same sound track as that of the second resonator, and reflectors are formed on both sides of the IDTs. The surface acoustic wave device of claim 1, wherein a seismic propagation preventing groove having a predetermined depth is formed on the upper substrate between the first resonator and the second resonator. The dual surface acoustic wave device according to claim 1, wherein a depth of the elastic wave propagation preventing groove is formed deeper than a wavelength? Of resonance frequencies generated in the first resonator unit and the second resonator unit.