CN209299228U - Using the surface acoustic wave resonance Structure Filter in periodical poling area - Google Patents
Using the surface acoustic wave resonance Structure Filter in periodical poling area Download PDFInfo
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- CN209299228U CN209299228U CN201821959771.3U CN201821959771U CN209299228U CN 209299228 U CN209299228 U CN 209299228U CN 201821959771 U CN201821959771 U CN 201821959771U CN 209299228 U CN209299228 U CN 209299228U
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Abstract
The utility model belongs to the communications field, and in particular to a kind of resonance structure filter.One of the utility model surface acoustic wave resonance Structure Filter, it include: ferroelectricity chip, multiple resonator elements of wafer surface production and electrical connection metal electrode structure etc., resonator element is made of period metal electrode and confluence conductive metal electrode, and the ferroelectricity chip is the wafer using ferroelectric single crystal processing and fabricating；The ferroelectricity wafer surface has made at least one periodical poling area thereon；At least one resonator element is produced in periodical poling area；The periodical poling area for making ungrounded resonator element is isolated with other periodical poling areas；Electrical connection metal electrode structure is not produced in periodical poling area.The program reduces the energy loss scattered when acoustic surface wave propagation to wafer substrates, and reduces the technology difficulty of filter match capacitor manufacture.
Description
Technical field
The utility model belongs to the communications field, and in particular to a kind of resonance structure filter.
Background technique
The electromagnetic wave to various wave bands existing for space is needed to be selected and screened in modern communications, filter rises
To effect be exactly the electromagnetic wave for obtaining specific band.The quantity of required filter is about several in current every mobile phone
Ten, the quantity of the more required filters of frequency range also will increase.The SAW filter branch important as filter, work
Skill is simple, low in cost.The frequency characteristic and temperature characterisitic of SAW filter are the important parameter indexs of filter, greatly
The performance for affecting filtering.Therefore, it is particularly important to study and obtain SAW filter excellent frequency characteristic and temperature characterisitic.
Electricdomain is that ferroelectric single crystal material externally shows the ferroelectric Microscopic mechanism of macroscopic view.Exist inside ferroelectric material
Multiple electricdomains, positive and negative charge center is not overlapped in electricdomain, and positive and negative charge center is located at the two sides of electricdomain, so single electricdomain is external
It can show charging property, it is opposite at the charge polarity of 180 ° of angles in electricdomain.Since the direction of electricdomain and angle random arrange, because
This entire ferroelectric material does not show charging property, internal not stored charge externally.
Lithium niobate, lithium tantalate are single domain ferro-electricity single crystals, and farmland orientation only has both direction, and positive polarity farmland indicates farmland polarization side
To for+Z.Making devices generally uses single domain chip, i.e., entire all electricdomain polarization directions of inner wafer are consistent, this time domain orientation
It is not necessarily vertical with wafer surface, it is related to chip cut type；Domain wall is not present in single domain inner wafer, without charge accumulated.
Periodical poling refers to: in wafer surface specific region, so that the electricdomain polarity in the region is inverted 180 using specialized processes
Degree.Thus it will form domain boundary face, in this interface two sides, electric domain orientation is on the contrary, cause interface to accumulate like charges, composition domain boundary
Surface charge area.Domain boundary surface charge area, conductance is high, and being equivalent to ferro-electricity single crystal joined one layer of metal layer, produces to acoustic surface wave propagation
Raw limitation and reflection.Ferro-electricity single crystal domain reversal forms the signal of band electric domain wall as shown in Fig. 2, domain wall is as shown in 6..
The periodical poling area of this patent meaning as a result, refers to: in the poling of the single domains ferro-electricity single crystal such as lithium niobate, lithium tantalate
Wafer surface is produced and the opposite polarity thin layer area of the electricdomain of single domain chip using microelectronic process engineering.The periodical poling area
The domain boundary face that thin layer and chip are formed, has high conductivity, limits the surface acoustic wave propagated in this periodical poling area, that is, constitute
The waveguiding structure of surface acoustic wave.
Currently, having literature research influence of the periodical poling area to SAW device frequency and temperature characterisitic.Kiyoshi
[1] theory analysis such as Nakamura and experimental study prove that periodical poling area improves the temperature characterisitic of SAW device.Tantalic acid
On lithium chip, the temperature coefficient of delay is reduced to 12.6ppm/ °C by the presence in periodical poling area, when relative to no periodical poling area
2/3.Michio Miura etc. [2] forms periodical poling area in ferroelectricity wafer substrates, anti-by the structure and farmland that change resonator
Turn corresponding relationship between area, it was demonstrated that optimization of the periodical poling area to frequency characteristic and the raising to temperature stability.But meanwhile
Resonance filter, it was also found that if is entirely produced on ferroelectricity wafer substrate surface farmland polarization inversion region by Michio Miura etc.
On, then it is the insertion loss that will lead to SAW filter is big and frequency characteristic is poor, it is thus, bright in its Patent right requirement
It really proposes, the composition resonator element of resonance filter, can only be a part of and not all, it can be produced on domain on surface reversal zone.
【1】Kiyoshi Nakamura, Ailie Tourlog, ”Effect of a Ferroelectric
Inversion Layer on the Temperature Characteristics of SH-Type Surface
Acoustic Waves on 36Y-X LiTaO3 Substrates”, IEEE transactions on ultrasonics,
ferroelectrics, and frequency control, 1994 , 41 (6) :872-875.
【2】US Patent No: US6903630 (B2), Date of patent: Jun7,2005。
Utility model content
In order to solve the shortcomings of the prior art, it is humorous that the utility model provides a kind of surface acoustic wave that filtering performance is good
Vibration Structure Filter.
One of the utility model surface acoustic wave resonance Structure Filter, comprising: ferroelectricity chip, wafer surface production
Multiple resonator elements and electrical connection metal electrode structure etc., resonator element is by period metal electrode and confluence conductive metal electricity
Pole is constituted, it is characterized in that:
The ferroelectricity chip is the wafer using ferroelectric single crystal processing and fabricating；The ferroelectricity wafer surface, makes thereon
At least one periodical poling area；At least one resonator element is produced in periodical poling area；Make ungrounded resonator element
Periodical poling area be isolated with other periodical poling areas；Electrical connection metal electrode structure is not produced in periodical poling area.
Preferably, whole resonator elements are produced in periodical poling area.
Preferably, the periodical poling area of resonator element is made, shape just includes the period metal electricity of resonator element
Pole part.
The average value in the metal electrode period in period with a thickness of all resonator elements of filter of periodical poling area thin layer
(0.5 ~ 10) times.
Surface acoustic wave resonance Structure Filter further includes filter match capacitor, and the capacitor is by being produced on periodical poling
Metal electrode in area is to composition.
Preferably, ferro-electricity single crystal uses lithium niobate, lithium tantalate.
Periodical poling area where two or more ground connection resonator elements can be connected.
The period metal electrode of resonator element is to be made of single metal or multiple layer metal, such as common is Al,
Cu or Al/Cu.
It further include being covered on multiple resonator elements and electrical connection metal electrode on ferroelectricity chip for boostfiltering device performance
The multilayer dielectric film of superstructure.
Multilayer dielectric film, the bottom are certain thickness silica, and silicon oxide film surface is graduation.Top is
Certain thickness silicon nitride.
Pass through foregoing invention scheme, it is possible to reduce energy loss of the surface acoustic wave when wafer substrate surface is propagated reduces
Device Insertion Loss and temperature coefficient.
In particular, this technology side replaces the interdigital capacitor being widely used at present with plane capacitance, technique reality is greatly reduced
Existing difficulty.
The utility model has the beneficial effects that the energy damage scattered when the program reduces acoustic surface wave propagation to wafer substrates
Consumption, and reduce the technology difficulty of filter match capacitor manufacture.
Detailed description of the invention
Fig. 1 is schematic structural view of the invention.
Fig. 2 is ferro-electricity single crystal domain reversal schematic diagram.
Fig. 3 is the 1st embodiment schematic diagram of resonator type surface acoustic wave device.
Fig. 4 is the 2nd embodiment schematic diagram of resonator type surface acoustic wave device.
Fig. 5 is that periodical poling area and plane capacitance replace interdigital capacitor.
Fig. 6 is the 3rd embodiment schematic diagram of resonator type surface acoustic wave device.
Fig. 7 is the 3rd embodiment process schematic representation of resonator type surface acoustic wave device.Its technique implemented specifically includes following step
Rapid: S1. prepares ferroelectricity wafer substrates；S2. periodical poling area is made；S3. metal electrode is made；S4. SiO2 layers are deposited；S5. it deposits
SiN layer.
Marked in the figure: 1, ferroelectricity wafer substrates, 2, periodical poling area, 3, resonator unit, 4, metal connection electrode, 5, flat
Face capacitor.
Specific embodiment
The utility model is described in further detail with reference to the accompanying drawing, but this should not be interpreted as the utility model
The range of above-mentioned theme is only limitted to above-described embodiment.
As shown in Figure 1, a kind of resonator type surface acoustic wave device includes the resonator element 3 being successively arranged from top to bottom, farmland
Reversal zone 2 and ferroelectricity wafer substrates 1.As shown in Fig. 2, ferro-electricity single crystal electricdomain generates charge product at the domain wall in domain reversal
It is tired.
The fundamental technology process of embodiment is as follows:
Using Czochralski grown lithium tantalate (LiTaO3) crystal bar, lithium tantalate is produced by processes such as cutting, grinding, polishings
(LiTaO3) wafer substrates, and cleaned to wafer substrates；
The surface deposition 300nm tantalum film of lithium tantalate (LiTaO3) ferroelectricity wafer substrates, makes exposure mask, and protection is not required to reversion
Region；
LiTaO3 ferroelectricity wafer substrates are immersed to the pyrophosphoric acid that concentration is 90% under 260 DEG C of high temperature, the time is 20 minutes；
Then, ferroelectricity wafer substrates are annealed 1-3 hours under the be just below proper temperature of the Curie temperature of LiTaO3, temperature is about
605℃；When the time for immersing pyrophosphoric acid is 20 minutes, the thickness in periodical poling area is about 1 μm；It is 30 minutes when immersing the time
When, thickness is about 1.5 μm；
Then use the techniques such as photoetching, vacuum coating by multiple resonator electrode configuration units and metal connection electrode figure
Manufacture is on corresponding region.
Embodiment 1:
As shown in figure 3, resonator type surface acoustic wave device is 3 series resonators and the resonance that 2 parallel resonators are constituted
Mode filter includes period metal electrode and confluence conductive metal electrode and reflecting grating.Metal connection electrode 4 and ferroelectricity chip
1 surface of substrate does not make periodical poling area.
It is logical that resonator is produced on lithium niobate, 1,3 series resonators of lithium tantalate wafer substrate surface and 2 parallel resonators
Cross the connection of surface metal electrode.
Periodical poling area is formed in the lower section of 3 series resonators and 2 parallel resonators.
The shape in periodical poling area just covers resonator.
Periodical poling area with a thickness of the average value in resonator metal electrode period (0.5 ~ 10) times.
Resonator period metal electrode material is Al, Cu or Al/Cu.
Embodiment 2:
As shown in figure 4, resonator type surface acoustic wave device be for by 3 series resonators, 2 parallel resonators and 1 simultaneously
Join capacitor composition.
Ferroelectricity wafer substrates 1 are lithium niobate, lithium tantalate ferro-electricity single crystal, and resonator is produced on ferroelectricity wafer substrate surface, 3
Series resonator and 2 parallel resonators and plane capacitance are connected by surface metal electrode 4.
Periodical poling area 2 is produced on series resonator, the lower section of parallel resonator and plane capacitance.
As shown in figure 5, capacitance structure, the invention design scheme shunt capacitance is designed as periodical poling area and plane capacitance, takes
For existing interdigital capacitor, the technology difficulty of SAW device capacitance structure realization is reduced.
The range in periodical poling area just includes resonator element, with a thickness of the period gold of all resonator elements of filter
Belong to (0.5 ~ 10) times of the average value in electrode period.
Its material is Al, Cu or Al/Cu.
Ungrounded resonator periodical poling area is not connected to, is mutually isolated, and the periodical poling area for being grounded resonator is mutually to interconnect
Logical.
Embodiment 3:
Surface acoustic wave resonance Structure Filter as shown in Figure 6 includes ferroelectricity wafer substrates 1, periodical poling area 2, resonator element
3 and metal connection electrode 4, it is the resonator type surface acoustic wave device with temperature compensation effect, is made below resonator
There is periodical poling area.
The meeting occurrence frequency drift in the case where temperature changes of common SAW device, and be all negative temperature system
Number, in order to guarantee the stabilization of frequency, it is necessary to increase by one layer of medium with positive temperature coefficient and compensate, commonly be situated between for SiO2
Matter.The process that its technique is realized, which is increased, is used for the SiO2 dielectric layer and deposited silicon nitride of temperature-compensating in wafer surface deposit
Layer, and partial electrode and the external channel for forming electric signal are leaked out by photoetching process.Technical process is as shown in Figure 7.
The material of ferroelectricity wafer substrates be lithium niobate, lithium tantalate, ground connection and ungrounded resonator be respectively positioned on periodical poling area it
On.
The range in periodical poling area just includes the period metallic electrode portion of resonator, periodical poling area with a thickness of metal electricity
(0.5 ~ 10) of the average value of polar period times.
Resonator period metal electrode material is what Al, Cu or Al/Cu were constituted.
Resonator surface covers multilayer dielectric film, and the bottom is certain thickness silica, and top is certain thick
The silicon nitride of degree, silica layer surface are graduations.
Claims (10)
1. a kind of surface acoustic wave resonance Structure Filter, comprising: ferroelectricity wafer substrates are arranged on ferroelectricity wafer substrate surface
Multiple resonator elements and electrical connection metal electrode structure, resonator element is by period metal electrode and confluence conductive metal electrode
It constitutes, it is characterized in that:
The ferroelectricity wafer substrates are the wafers using ferroelectric single crystal processing and fabricating；
The ferroelectricity wafer substrate surface is equipped at least one periodical poling area；
At least one resonator element is arranged in periodical poling area；
Periodical poling area equipped with resonator element is isolated with other periodical poling areas；
Electrical connection metal electrode structure is not arranged in periodical poling area.
2. surface acoustic wave resonance Structure Filter according to claim 1, it is characterized in that: whole resonator elements make
In periodical poling area.
3. surface acoustic wave resonance Structure Filter according to claim 1, it is characterized in that: further including filter match electricity consumption
Hold, filter match capacitor is by the metal electrode that is arranged in periodical poling area to constituting.
4. surface acoustic wave resonance Structure Filter according to claim 1, it is characterized in that: ferro-electricity single crystal is lithium niobate, tantalum
Sour lithium.
5. surface acoustic wave resonance Structure Filter according to claim 1, it is characterized in that: two or more ground connection resonators
What the periodical poling area where unit was connected to connect.
6. surface acoustic wave resonance Structure Filter according to claim 1, it is characterized in that: periodical poling area includes resonator list
The period metallic electrode portion of member.
7. surface acoustic wave resonance Structure Filter according to claim 1, it is characterized in that: periodical poling area thickness of thin layer is filter
0.5 ~ 10 times of the average value in the metal electrode period in period of all resonator elements of wave device.
8. surface acoustic wave resonance Structure Filter according to claim 1, it is characterized in that: the period metal of resonator element
Electrode is made of single metal or multiple layer metal.
9. surface acoustic wave resonance Structure Filter according to claim 8, it is characterized in that: the period metal of resonator element
Electrode is made of Al, Cu or Al/Cu.
10. surface acoustic wave resonance Structure Filter according to claim 1, it is characterized in that: further including being covered on ferroelectricity crystalline substance
Multilayer dielectric film above the multiple resonator elements of on piece and electrical connection metal electrode structure.
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| CN201821959771.3U CN209299228U (en) | 2018-11-27 | 2018-11-27 | Using the surface acoustic wave resonance Structure Filter in periodical poling area |
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