CN1921301B

CN1921301B - Surface acoustic wave element

Info

Publication number: CN1921301B
Application number: CN2005100369163A
Authority: CN
Inventors: 颜硕廷
Original assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Current assignee: Hongfujin Precision Industry Shenzhen Co Ltd; Hon Hai Precision Industry Co Ltd
Priority date: 2005-08-26
Filing date: 2005-08-26
Publication date: 2010-09-29
Anticipated expiration: 2025-08-26
Also published as: CN1921301A

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 element

[technical field]

The invention relates to a kind of surface acoustic wave element, especially about a kind of surface acoustic wave element with less insertion loss.

[background technology]

Surface acoustic wave element is to be used in the ripple of propagating on a kind of elastic solid (Hookean body) surface, carries out the signal of telecommunication and handles.Typical surface acoustic wave element is to utilize a transducer, will convert the sound signal ripple slower than the light velocity with the electromagnetic signal ripple of light velocity propagation to.This significant wavelength reduces to make the designer in than the much smaller space of traditional circuit design requisite space, implements some complicated signal processing functions.The surface acoustic wave element that has adopted advanced microelectronic processing technique to make, have that volume is little, in light weight, reliability is high, high conformity and advantage such as multi-functional, in systems such as communication, TV, remote control and warning, be used widely, for example be used for filter, resonator, oscillator, delay line and other similar device, all used a plurality of surface acoustic wave filters in hundreds of millions of mobile phones and the television set.Along with the develop rapidly of processing technology, surface acoustic wave element has become one of indispensable key components of modern information industry.

A kind of existing surface acoustic wave element is to be produced on the piezoelectric substrate, adopt microelectronic process engineering to make interdigital transducer and reflector etc., utilize the piezoelectric effect of substrate material, (Inter Digital Transducer IDT) converts the electrical signal to acoustical signal, and is confined to the substrate surface propagation by the input interdigital transducer, output interdigital transducer reverts to the signal of telecommunication with acoustical signal, realize the conversion process of electricity-sound-electricity, finish signal of telecommunication processing procedure, obtain the electronic device of various uses.The effect of reflector is that the energy reflection with transducer terminal loss returns in the transducer.The physical dimension of the interdigital transducer on the piezoelectric substrate, for example interdigital bar height, pitch and number play an important role for the signal processing and the frequency response characteristic of a surface acoustic wave element.The designer of surface acoustic wave element is usually when surface acoustic wave element reaches the required frequency response of work, in the selection of the physical dimension of concentrating on surface acoustic wave element and piezoelectric substrate institute materials used.Yet existing surface acoustic wave element with interdigital transducer, its electrode are even overlapping electrode, and this design can not reduce the insertion loss of surface acoustic wave element effectively.

[summary of the invention]

At the problems referred to above, be necessary to provide a kind of and have than low insertion loss and the higher surface acoustic wave element of design freedom.

A kind of surface acoustic wave element, it comprises a piezoelectric substrate, one first transducer and one second transducer, this first transducer and this second transducer are located on the same surface of this piezoelectric substrate, and this first transducer and this second transducer acoustical coupling; Wherein, each transducer comprises one first electrode and one second electrode, and this first electrode is opposite with second polarity of electrode, arranged side by side mutually also to surround a spiral respectively, and the pitch of each spiral is a surface acoustic wave wavelength.

Compare prior art, the electrode of described surface acoustic wave element surrounds into a helical form alternately, thereby its overlap length is long, can effectively reduce the insertion loss.In addition, parameters such as the length of described spiral electrode, width and spacing, can constantly change in design, thus parameters such as the insertion loss of control surface acoustic elecment, frequency range and surface acoustic wave speed, thus the design freedom of raising surface acoustic wave element and application system thereof.

[description of drawings]

Fig. 1 is the perspective view of the surface acoustic wave element of preferred embodiment of the present invention;

Fig. 2 is the making schematic flow sheet of the surface acoustic wave element of preferred embodiment of the present invention.

[embodiment]

Preferred embodiment of the present invention discloses a kind of surface acoustic wave element 1, sees also Fig. 1, and this surface acoustic wave element 1 comprises substrate 10, piezoelectric thin film layer 20, first transducer 30 and second transducer 40.Substrate 10 is to be fabricated from a silicon, piezoelectric thin film layer 20 is formed on the upper surface of this substrate 10, this piezoelectric thin film layer 20 is to be made by zinc oxide (ZnOx), lithium niobate (LiNbOx), lithium titanate (LiTiOx) or lithium tantalate materials such as (LiTaOx), first transducer 30 has one first electrode 32 and one second electrode 34 and an electric signal input end 36 of two opposite sex, the material of described first electrode 32 and second electrode 34 can be gold, silver, copper or aluminium, it surrounds helical form mutually side by side, and electric signal input end 36 is positioned at a terminal of first electrode 32 and second electrode 34.Wherein, apart from being preferably a surface acoustic wave wavelength, distance is preferably the surface acoustic wave wavelength half between the adjacent two different in nature electrodes between adjacent two same sex electrodes.Second transducer 40 is identical with first transducer, 30 structures, has two different in

nature electrode

42,44 and electrical signals 46, and electrical signal 46 is positioned at a terminal of two electrodes 42,44.And

first transducer

30 and 40 acoustical couplings of second transducer.

During surface acoustic wave element 1 work, the electric signal input end 36 of first transducer 30 receives the outside signal of telecommunication, because piezoelectric thin film layer 20 has piezoelectric property, helical form first electrode 32 of first transducer 30 and second electrode 34 become surface acoustic wave with the electrical signal conversion that receives, this surface acoustic wave is transmitted to second transducer 40 along piezoelectric thin film layer 20, the

electrode

42,44 of second transducer 40 converts surface acoustic wave to the signal of telecommunication, by electrical signal 46 outputs of second transducer 40.

The electrode of the disclosed surface acoustic wave element of preferred embodiment of the present invention surrounds into a helical form alternately, thereby its overlap length is long, can effectively reduce the insertion loss.In addition, parameters such as the length of this surface acoustic wave element spiral electrode, width and spacing, can constantly change in design, thus parameters such as the insertion loss of control surface acoustic elecment, frequency range and surface acoustic wave speed, thus the design freedom of raising surface acoustic wave element and application system thereof.

See also Fig. 2, the manufacture method of this surface acoustic wave element 1 may further comprise the steps:

One silicon chip 10 at first is provided; Then this silicon chip 10 is placed in the vacuum chamber, with zinc oxide (ZnOx), lithium niobate (LiNbOx), lithium titanate (LiTiOx) or lithium tantalate (LiTaOx) is sputtered target material, is sputter gas with argon gas (Ar) with oxygen, at surperficial sputter one piezoelectric thin film layer 20 of this silicon chip 10, method for sputtering can be reactive dc sputtering (DC reactivesputtering) or reactive radio frequency sputter (RF reactive sputtering); At piezoelectric thin film layer 20 surface applied one deck photoresist layers 50; Then a light shield (figure does not show) is covered in this photoresist layer 50 surfaces; With laser light or this light shield of UV-irradiation, form an exposure region on the photoresistance surface; After taking off light shield, the photoresist layer 50 that exposes is placed in the developer solution, remove the exposure photoresistance 501 of exposure region, exposed portions serve piezoelectric thin film layer 201; Then utilize sputtering method at the part piezoelectric thin film layer 201 surface plating one deck conductive metal films 60 that remain photoresistance and expose, this metal can be gold, silver, copper or aluminium; Flush away residue photoresistance and metallic diaphragm 60 attached to it, then remaining metallic diaphragm is two electrodes of

transducer

30,40, and this two electrode surrounds helical form mutually side by side, has just made described surface acoustic wave element 1 this moment.

Claims

1. surface acoustic wave element, it is characterized in that: this surface acoustic wave element comprises a piezoelectric substrate and two transducers, this two transducer is located on the same surface of this piezoelectric substrate, and its mutual acoustical coupling, wherein each transducer comprises one first electrode and one second electrode, this first electrode is opposite with second polarity of electrode, arranged side by side mutually also to surround a spiral respectively, and the pitch of each spiral is a surface acoustic wave wavelength.

2. surface acoustic wave element as claimed in claim 1 is characterized in that: this piezoelectric substrate comprises that a substrate and is located at on-chip piezoelectric thin film layer.

3. surface acoustic wave element as claimed in claim 2 is characterized in that: the material of this substrate is a silicon.

4. surface acoustic wave element as claimed in claim 2 is characterized in that: the material of this piezoelectric thin film layer is a kind of in zinc oxide, lithium niobate, lithium titanate and the lithium tantalate.

5. surface acoustic wave element as claimed in claim 1 is characterized in that: the material of this first electrode and second electrode is a kind of in gold, silver, copper and the aluminium.

6. surface acoustic wave element as claimed in claim 1 is characterized in that: the spacing between two spirals of each transducer is half surface acoustic wave wavelength.