CN1921301B - Surface Acoustic Wave Components - Google Patents

Abstract

The invention relates to a surface sonic wave element, which comprises one piezoelectric base plate, the first energy exchanger and the second energy exchanger that on the base plate and coupled. Wherein, at least one energy exchanger has two electrodes parallel in screw shape. Compared with present technique, the inventive electrodes are alternated into screw shape, to obtain long supposition length and reduce the insertion consumption; in addition, the parameters of screw electrode as length, etc can be changed to control the insertion consumption, frequency width, etc.

Description

Surface Acoustic Wave Components

【Technical field】

The invention relates to a surface acoustic wave element, in particular to a surface acoustic wave element with relatively small insertion loss.

【Background technique】

Surface acoustic wave components use waves propagating on the surface of an elastic solid for electrical signal processing. A typical surface acoustic wave device uses a transducer to convert electromagnetic signal waves traveling at the speed of light into acoustic signal waves slower than the speed of light. This dramatic wavelength reduction allows designers to implement some complex signal processing functions in a much smaller footprint than traditional circuit designs require. The surface acoustic wave components manufactured by advanced microelectronic processing technology have the advantages of small size, light weight, high reliability, good consistency and multi-function, and have been widely used in communication, television, remote control and alarm systems, such as Used in filters, resonators, oscillators, delay lines, and other similar devices, multiple SAW filters are used in hundreds of millions of mobile phones and televisions. With the rapid development of processing technology, surface acoustic wave components have become one of the indispensable key components in the modern information industry.

A kind of existing surface acoustic wave element is made on a piezoelectric substrate, adopts microelectronics technology to make interdigital transducer and reflector etc., utilizes the piezoelectric effect of substrate material, through input interdigital transducer (Interdigital transducer) Digital Transducer, IDT) converts the electrical signal into an acoustic signal and spreads it on the surface of the substrate, and the output interdigital transducer restores the acoustic signal into an electrical signal, realizing the conversion process of electricity-acoustic-electricity, and completing the electrical signal processing process , to obtain electronic devices for various purposes. The function of the reflector is to reflect the energy lost at the end of the transducer back into the transducer. The geometric dimensions of the IDTs on the piezoelectric substrate, such as the bar height, pitch, and number of fingers, play an important role in the signal processing and frequency response characteristics of a SAW device. Designers of SAW components typically focus on the geometry of the SAW component and the choice of materials used for the piezoelectric substrate when the SAW component achieves the frequency response required for operation. However, the electrodes of the existing surface acoustic wave element with interdigital transducers are evenly overlapped electrodes, and this design cannot effectively reduce the insertion loss of the surface acoustic wave element.

【Content of invention】

In view of the above problems, it is necessary to provide a surface acoustic wave element with lower insertion loss and higher design freedom.

A surface acoustic wave element comprising a piezoelectric substrate, a first transducer and a second transducer, the first transducer and the second transducer are arranged on the same surface of the piezoelectric substrate, And the first transducer is acoustically coupled to the second transducer; wherein each transducer includes a first electrode and a second electrode, and the first electrode and the second electrode have opposite polarities and are parallel to each other A helix is formed respectively, and the pitch of each helix is one surface acoustic wave wavelength.

Compared with the prior art, the electrodes of the surface acoustic wave element alternately surround each other in a helical shape, so the overlapping length is long, which can effectively reduce the insertion loss. In addition, parameters such as the length, width, and spacing of the spiral electrodes can be continuously changed in design, thereby controlling parameters such as insertion loss, bandwidth, and surface acoustic wave velocity of the surface acoustic wave element, thereby improving the surface acoustic wave element and its application system. design freedom.

【Description of drawings】

FIG. 1 is a schematic diagram of a three-dimensional structure of a surface acoustic wave element in a preferred embodiment of the present invention;

FIG. 2 is a schematic diagram of the manufacturing process of the surface acoustic wave device according to the preferred embodiment of the present invention.

【Detailed ways】

A preferred embodiment of the present invention discloses a surface acoustic wave device 1 , please refer to FIG. 1 , the surface acoustic wave device 1 includes a substrate 10 , a piezoelectric film layer 20 , a first transducer 30 and a second transducer 40 . The substrate 10 is made of silicon material, and the piezoelectric film layer 20 is formed on the upper surface of the substrate 10. The piezoelectric film layer 20 is made of zinc oxide (ZnOx), lithium niobate (LiNbOx), lithium titanate ( LiTiOx) or lithium tantalate (LiTaOx) and other materials, the first transducer 30 has a first electrode 32, a second electrode 34 and an electrical signal input terminal 36 of diisotropy, the first electrode 32 and The material of the second electrode 34 can be gold, silver, copper or aluminum, and they are arranged side by side to form a spiral shape. The electrical signal input terminal 36 is located at one end of the first electrode 32 and the second electrode 34 . Wherein, the distance between adjacent two opposite electrodes is preferably one surface acoustic wave wavelength, and the distance between adjacent two opposite electrodes is preferably half a surface acoustic wave wavelength. The second transducer 40 has the same structure as the first transducer 30 , and has two opposite electrodes 42 , 44 and an electrical signal output terminal 46 . The electrical signal output terminal 46 is located at a terminal of the two electrodes 42 , 44 . And the first transducer 30 is acoustically coupled to the second transducer 40 .

When the surface acoustic wave element 1 is working, the electrical signal input terminal 36 of the first transducer 30 receives an external electrical signal. Since the piezoelectric film layer 20 has piezoelectric properties, the helical first electrode 32 of the first transducer 30 and The second electrode 34 converts the received electrical signal into a surface acoustic wave, and the surface acoustic wave propagates along the piezoelectric film layer 20 to the second transducer 40, and the electrodes 42, 44 of the second transducer 40 convert the surface acoustic wave into an electrical signal. The signal is output by the electrical signal output terminal 46 of the second transducer 40 .

The electrodes of the surface acoustic wave device disclosed in the preferred embodiment of the present invention are alternately wound into a helical shape, so the overlapping length is long, which can effectively reduce the insertion loss. In addition, parameters such as the length, width, and spacing of the spiral electrodes of the surface acoustic wave element can be continuously changed in design, thereby controlling parameters such as insertion loss, bandwidth, and surface acoustic wave velocity of the surface acoustic wave element, thereby improving the surface acoustic wave element and its performance. Application system design freedom.

Referring to Fig. 2, the manufacturing method of the surface acoustic wave element 1 includes the following steps:

First provide a silicon substrate 10; then place the silicon substrate 10 in a vacuum chamber with zinc oxide (ZnOx), lithium niobate (LiNbOx), lithium titanate (LiTiOx) or lithium tantalate (LiTaOx) as the sputter Plating the target material, using argon (Ar) and oxygen as the sputtering gas, sputtering a piezoelectric thin film layer 20 on the surface of the silicon substrate 10, the sputtering method can be reactive DC sputtering (DC reactive sputtering) or reaction RF reactive sputtering (RF reactive sputtering); a layer of photoresist layer 50 is coated on the surface of the piezoelectric film layer 20; then a photomask (not shown) is covered on the surface of the photoresist layer 50; Light irradiates the photomask to form an exposure area on the surface of the photoresist; after removing the photomask, place the exposed photoresist layer 50 in a developing solution, remove the exposure photoresist 501 in the exposure area, and expose part of the piezoelectric film layer 201 ; Then use sputtering method to plate a layer of conductive metal film 60 on the surface of the remaining photoresist and the exposed part of the piezoelectric film layer 201, the metal can be gold, silver, copper or aluminum; wash off the remaining photoresist and adhere to it The metal film layer 60, the remaining metal film layer is the two electrodes of the transducers 30, 40, and the two electrodes are juxtaposed with each other to form a spiral shape. At this time, the surface acoustic wave element 1 has been produced.

Claims (6)

1. A surface acoustic wave element, characterized in that: the surface acoustic wave element comprises a piezoelectric substrate and two transducers, the two transducers are arranged on the same surface of the piezoelectric substrate, and are acoustically coupled to each other, wherein each A transducer includes a first electrode and a second electrode, the first electrode and the second electrode have opposite polarities, are juxtaposed with each other and respectively surround a helix, and the pitch of each helix is one surface acoustic wave wavelength. 2. The surface acoustic wave device as claimed in claim 1, wherein the piezoelectric substrate comprises a substrate and a piezoelectric film layer disposed on the substrate. 3. The surface acoustic wave device as claimed in claim 2, wherein the substrate is made of silicon. 4 . The surface acoustic wave device according to claim 2 , wherein the piezoelectric film layer is made of one of zinc oxide, lithium niobate, lithium titanate and lithium tantalate. 5. The surface acoustic wave device as claimed in claim 1, wherein the material of the first electrode and the second electrode is one of gold, silver, copper and aluminum. 6. The surface acoustic wave device as claimed in claim 1, wherein the distance between the two helices of each transducer is half the wavelength of the surface acoustic wave.

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