WO2020133316A1

WO2020133316A1 - Resonator having split structure

Info

Publication number: WO2020133316A1
Application number: PCT/CN2018/125235
Authority: WO
Inventors: 张孟伦; 庞慰; 杨清瑞
Original assignee: 天津大学; 诺思(天津)微系统有限责任公司
Priority date: 2018-12-29
Filing date: 2018-12-29
Publication date: 2020-07-02

Abstract

Disclosed is a resonator having a split structure. The resonator consists of several sub-resonators forming a resonator group, and an equivalent impedance of the resonator group is equal to an impedance of a single resonator in the prior art. Every two adjacent sub-resonators are at most electrically connected and remain acoustically isolated from each other. Each of the sub-resonators comprises a lower electrode, a piezoelectric layer, and an upper electrode. The invention increases equivalent areas, and further increases perimeter area ratios of resonators, thereby improving the heat dissipation performance of the resonators and the overall power capacity of electronic devices.

Description

Split structure resonator

Technical field

The invention relates to a resonator, in particular to a split structure resonator.

Background technique

Thin-film bulk wave resonators made by longitudinal resonance of piezoelectric films in the thickness direction have become a viable alternative to surface acoustic wave devices and quartz crystal resonators in mobile phone communications and high-speed serial data applications. The RF front-end bulk wave filter/duplexer provides superior filtering characteristics, such as low insertion loss, steep transition band, and strong anti-static discharge (ESD) capability. With the continuous improvement of the power capacity requirements of electronic devices such as filters and resonators in the fields of communications and the like, the heat generation of filters and resonators has increased significantly. The high temperature caused by high heat will cause the device Q value and electromechanical coupling coefficient to decrease greatly; in addition, the high temperature will cause the frequency of the resonator to drift; in addition, the high temperature will also reduce the overall life of the device. The above problems ultimately lead to serious deterioration of the performance parameters of the filter composed of resonators such as bandwidth, insertion loss, roll-off characteristics, and out-of-band suppression.

The traditional approach to the problem of heat generation is to increase the area of the resonator. This method can effectively reduce the power density in the resonator within a certain power range, thereby reducing the operating temperature of the resonator. However, relying solely on the method of increasing the area can no longer meet the current requirements of the resonator on power capacity, and further improvement of the traditional structure is needed.

Summary of the invention

The object of the present invention is to provide a split structure resonator, which not only increases the equivalent area, but also increases the perimeter area ratio of the resonator, thereby improving the heat dissipation performance of the resonator and the overall power capacity of the electronic device.

A split structure resonator, the split structure resonator is a resonator group composed of several sub-resonators, the equivalent impedance of the resonator group is equal to the impedance of the original single resonator; each two adjacent At most, there is only electrical connection between the sub-resonators, while acoustic isolation is maintained; each of the sub-resonators includes a lower electrode, a piezoelectric layer, and an upper electrode.

Optionally, two pins are provided on the resonator group, and the two pins occupy the first potential point and the second potential point, respectively, and are connected to other electronic components.

Optionally, the upper electrode and/or the lower electrode of the sub-resonator are electrically connected to the upper electrode and/or the lower electrode of the adjacent sub-resonator.

Optionally, the C axis of the piezoelectric layer of the sub-resonator points from one potential point to another potential point;

Alternatively, the C axis of a part of the piezoelectric layer of the resonator may be directed from the first potential point to the second potential point; the C axis of the piezoelectric layer of the other part of the resonator may be directed to the first potential point by the second potential point.

Optionally, the circuits of the resonator group are composed of several units connected in series; n (n>1) sub-resonators are connected in parallel in each unit and/or m circuits are connected in series ( m>1) unit.

Optionally, the unit has a certain resonator piezoelectric layer'C-axis orientation configuration', the C-axis orientation configuration requirement: the C-axis orientation of one sub-resonator and the other sub-resonators in the unit are the same or The C axis of at least one of the sub-resonators and the other sub-resonators in the unit points in opposite directions.

Optionally, a certain unit and the rest of the units have a certain'unit C axis configuration' relationship, and the relationship requires that a certain unit and the remaining units have the same unit C axis configuration relationship or a certain The unit and at least one of the remaining units have opposite unit C-axis configuration relationships.

Optionally, the unit is formed by connecting at least two adjacent sub-resonators in parallel and in series with at least one other sub-resonator.

Optionally, the upper electrode and the lower electrode are made of metal, a multi-layer composite material or alloy of metal; the metal includes at least one of the following: molybdenum, ruthenium, gold, magnesium, aluminum, tungsten, titanium, Chromium, iridium, osmium.

Optionally, the material of the piezoelectric layer includes at least one of the following: aluminum nitride, zinc oxide, lead zirconate titanate (PZT), and the piezoelectric material is doped with rare earth elements.

The beneficial effect of the present invention lies in that, under the premise that the equivalent impedance is the same, splitting a resonator into multiple parts can increase the power capacity. The use of pure series splitting will make the area of each sub-resonator larger. Although the larger area brings about a reduction in power density, if the resonator area is too large, the thermal gradient and temperature distribution in each resonator will be more uneven , Resulting in a sharp decline in the performance of the resonator under high power input; at the same time, the increase in area also causes the resonator to deteriorate in rigidity, which aggravates the deformation of the resonator under stress, resulting in a decrease in the Q value of the resonator, which eventually causes the device performance to deteriorate and stabilize Problems such as poor performance, shortened life span, and overall filter size are too large; and the simple parallel split method will make the area of each sub-resonator smaller, making the perimeter area ratio of the resonator too large, resulting in each resonance The energy loss rate of the resonator increases, thereby reducing the Q value of each resonator, which will also affect the performance of the resonator. Therefore, in order to overcome the above-mentioned problems, the present invention adopts a circuit configuration mode combined in parallel and series splitting mode to make the area of each sub-resonator moderate, while improving the power capacity of the resonator.

BRIEF DESCRIPTION

FIG. 1 is a schematic top view of Embodiment 1 of the present invention;

2 is a circuit diagram of Embodiment 1 of the present invention;

2a is another circuit diagram of Embodiment 1 of the present invention;

2b is another circuit diagram of Embodiment 1 of the present invention;

2c is another circuit diagram of Embodiment 1 of the present invention;

3 is a circuit diagram of Embodiment 2 of the present invention;

4 is another circuit diagram of Embodiment 2 of the present invention;

FIG. 5 is an illustrative example 1a;

Figure 6 is an illustrative example 1b;

Figure 7 is an illustrative example 1c;

Figure 8 is an illustrative example 1d;

Fig. 9 is an explanatory example 1e.

In the figure, the lower electrode 100, the piezoelectric layer 120 and the upper electrode 130 are shown.

detailed description

The following are preferred embodiments of the present invention, but do not limit the scope of protection of the present invention.

Example 1:

A100 splits the traditional single resonator into four resonators R101, R102, R103 and R104, and its abstract circuit diagram is shown in Figure 2.

The principle of A100's resonator splitting is equivalent impedance splitting, which ensures that the equivalent impedance of the split resonator group is equal to the impedance of the original single resonator.

Figure 1 shows the basic structure of the 4 resonator and the specific connection method:

Each resonator (taking R101 as an example) has a lower electrode 100, a piezoelectric layer 120, and an upper electrode 130.

The upper electrode of R101 has a pin C100, and the upper electrode of R101 is electrically connected to the upper electrode of R102 C101, the lower electrode of R101 is electrically connected to the lower electrode of R102 C103; the lower electrode of R102 is electrically connected to the lower electrode of R103 C104; and the upper electrode of R103 and the upper electrode of R104 are electrically connected to C102, the lower electrode of R103 and the lower electrode of R104 are electrically connected to C105, and the upper electrode of R104 has a pin C106.

Here, R101 and R102 are connected in parallel to ensure that the input voltages of the two resonators are absolutely the same, thereby ensuring that the electrical responses of the two resonators are exactly the same or opposite, thereby eliminating the influence of the resonator nonlinearity or enhancing the resonance characteristics; the same, The same effect can also be achieved by connecting R103 and R104 in parallel.

It should be noted here that the above-mentioned upper electrode and the lower electrode are made of a multi-layer composite material of molybdenum or magnesium; at most, there is only an electrical connection between each two adjacent resonators, while acoustically maintaining isolation.

In addition, the circuit structure of FIG. 2 can be further extended to: (1) In each parallel unit (such as the parallel unit U101 formed by R101 and R103), more sub-resonators are connected in parallel (as shown in FIG. 2a); (2) Add more resonators in series on each branch of each parallel unit; or (3) Add more parallel units in series on the basis of Figure 2 (such as the parallel unit formed by R101 and R103) (as shown in Figure 2b) Shown); or (4) combining the methods of (1), (2) and (3).

For the circuit shown in FIG. 2 and the circuit expanded in the above manner, the direction and composition of the C axis of the resonator can be in the following forms:

(1) The C axis of all resonators is directed from the first potential to the second potential; or from the second potential to the first potential.

(2) The C axis of some resonators is directed from the first potential to the second potential; the C axis of the other resonators is directed from the second potential to the first potential.

In case (2), optionally, the C-axis of any two resonators in a certain unit (such as U101) assumes the configuration of S1 or S2. At least one of the remaining expansion units is in AU or SU relationship with the above units; further, if there are p units in SU relationship with each other, and q units are in AU relationship with the p units above, then p can be equal to q , And the circuit may have a certain symmetry (such as periodicity or axis symmetry) in the spatial arrangement.

Or optionally, the C-axis of at least two resonators in a unit (such as U101) is formed of A1 or A2. Further, the number of resonators with opposite C-axis directions in a unit can be equal, And the circuit may have a certain symmetry (such as periodicity or axis symmetry) in the spatial arrangement.

At least one of the remaining expansion units is in AU or SU relationship with the above units; further, if there are p units in SU relationship with each other, and q units are in AU relationship with the p units above, then p can be equal to q , And the circuit may have a certain symmetry (such as periodicity or axis symmetry) in the spatial arrangement.

The use of A1 and A2 type crystal structure and the relationship between the AU and SU unit C-axis structure can effectively suppress the nonlinear effects of the circuit, such as the suppression of the 2nd and 3rd harmonics.

The piezoelectric layer is made of aluminum nitride material or zinc oxide material doped with rare earth elements. The piezoelectric material is a thin film with a thickness of less than 10 microns. The aluminum nitride film is in a polycrystalline or single crystal form, and the growth method is thin film sputtering (sputtering) or organic metal chemical vapor deposition (MOCVD). In addition, the piezoelectric material can also be doped with a certain proportion of rare earth element impurities.

The above method requires that the final equivalent impedance remains unchanged.

Example 2:

A200 splits the traditional single resonator into 6 resonators R201, R202, R203, R204, R205 and R206. The abstract circuit diagram is shown in Figure 3.

The principle of A200's resonator splitting is equivalent impedance splitting, that is, to ensure that the equivalent impedance of the split resonator group is equal to the impedance of the original single resonator (for example, 50Ω).

Figure 3 shows the specific connection of 6 resonators:

The upper electrode of R201 has pin C200, and the upper electrode of R201 is electrically connected to the upper electrode of R202 C201; the lower electrode of R201 is electrically connected to the lower electrode of R203 C204; the lower electrode of R202 is electrically connected to the lower electrode of R203 C205; the upper electrode of R203 and the upper electrode of R204 are electrically connected C202; the upper electrode of R204 and the upper electrode of R205 are electrically connected C203; the lower electrode of R204 and the lower electrode of R206 are electrically connected C206; the lower electrode of R205 and R206 The lower electrode is electrically connected to C207, and the upper electrode of R206 has pin C208.

It should be noted here that the above-mentioned upper electrode and the lower electrode are made of ruthenium multi-layer composite material or gold; at most, there is only electrical connection between each two adjacent resonators, while maintaining acoustic isolation.

In addition, the circuit structure of FIG. 3 can be further expanded as follows: (1) more sub-resonators are connected in parallel in each parallel unit (such as the parallel unit formed by R201 and R202); (2) each in each parallel unit More sub-resonators are connected in series in the branch; or (3) more resonators are connected in series at the resonators in the series position of FIG. 3 (such as R203 and R206); or (4) based on FIG. 4 More units are connected in series (units U201 formed in the form of R201, R202 and R203, as shown in Figure 4); or (5) The ways of (1)-(4) are combined.

For the circuit shown in Fig. 3 and the circuit expanded in the above manner, the direction and composition of the C axis of the resonator can be in the following forms:

In case (2), the C-axis of any two resonators in a unit assumes the configuration of S1 or S2. At least one of the remaining expansion units is in AU or SU relationship with the above units; further, if there are p units in SU relationship with each other, and q units are in AU relationship with the p units above, then p can be equal to q , And the circuit may have a certain symmetry (such as periodicity or axis symmetry) in the spatial arrangement.

Or alternatively, the C-axis of at least two resonators in a unit is configured as A1 or A2. Further, the number of resonators with opposite C-axis directions in a unit can be equal, and the circuit is in space There can be some symmetry in the arrangement.

The piezoelectric layer is made of zinc oxide or lead zirconate doped with rare earth elements. The piezoelectric material is a thin film with a thickness of less than 10 microns. The aluminum nitride film is in a polycrystalline or single crystal form, and the growth method is thin film sputtering (sputtering) or organic metal chemical vapor deposition (MOCVD). In addition, the piezoelectric material can also be doped with a certain proportion of rare earth element impurities.

Example 3

This embodiment is a preliminary description of the composition of the C-axis orientation and C-axis orientation of the sub-resonator of the present invention:

The C-axis orientation is defined as the crystal axis of the aluminum nitride piezoelectric layer in a bulk acoustic wave resonator or a group of bulk acoustic wave resonators relative to the two electrode pins applied to the bulk acoustic wave resonator or the resonator group Of the potential on the two pins.

In the description example 1a, resonators R1 and R2 are connected in parallel between two different potential points P1 and P2, and one electrode of the resonator R1 has a potential P1 and the other electrode has a potential P2. The crystal axis of the piezoelectric layer in R1 is directed from the potential P1 side to the potential P2 side.

One electrode of the resonator R2 has a potential P1, and the other electrode has a potential P2. The crystal axis of the piezoelectric layer in R2 is directed from the potential P2 side to the potential P1 side.

Then for a given two reference potential points P1 and P2, it is said that the C axis of R1 and R2 are opposite. In addition, the reverse of R1 and R2 also includes that the C axis of R1 points from P2 to P1 and the C axis of R2 points from P1 to P2.

If the C axes of R1 and R2 are from P1 to P2, it is said that the C axes of R1 and R2 are in the same direction. In addition, the case where the C axes of R1 and R2 are in the same direction also includes that the C axes of R1 and R2 are both directed from P2 to P1.

The above description rules for the direction of the C axis of R1 and R2 are also applicable to the series connection shown in Example 1b, and the C axis pointing configuration refers to the relative relationship between the C axis pointing of another vibrator in a certain electrical link relationship .

In the description example 1a, the parallel structure of R1 and R2 forms a C-axis pointing configuration, and the c-axis of R1 and R2 are in the same direction, then the C-axis of R1 and R2 is said to be a parallel C-axis configuration (referred to as S1 for short) Configuration), otherwise called anti-parallel C-axis configuration (referred to as A1 configuration).

Similarly, as shown in Example 1b, if R1 and R2 are in a series relationship, when the C-axis of R1 and R2 are in the same direction, the C-axis of R1 and R2 is said to be in the same-direction series C-axis configuration (referred to as S2 configuration); When the C-axis of R1 and R2 are reversed, the C-axis of R1 and R2 is said to be a reverse series C-axis configuration (referred to as the A2 configuration).

For a circuit connected in series and parallel, the C-axis configuration of some two resonators can also be defined. As shown in Example 1c, R1 and R2 form a parallel unit, and then in series with R3. The c-axis of R1 and R2 forms A1, the C-axis of R1 and R3 forms A2, and the C-axis of R2 and R3 forms S2.

Generally, the resonator circuit can be expanded by a certain structural unit. For example, as shown in Example 1d, the structure of the U1 unit is: R1 and R2 are connected in parallel and then in series with R3, and the structure in the U2 unit is the circuit structure of the U1 unit. repeat. At this time, if the C axis of each resonator (for example, R1) in U1 is the same as the C axis direction of the corresponding resonator (for example, R1') in U2, then U1 and U2 have the same The C-axis configuration of the unit (the C-axis configuration of the two units for short is SU relationship).

If the situation is shown in Figure 1e: that is, the C axis of each resonator in U1 (such as R1) is opposite to the C axis of the corresponding resonator in U2 (such as R1'), then U1 and U2 are said to have opposite The C-axis configuration of the unit (the C-axis configuration of the two units for short is AU relationship).

The split structure resonator designed by the present invention can increase the power capacity by splitting one resonator into multiple under the premise that the equivalent impedance is the same. The use of simple series splitting will make the area of each sub-resonator larger. Although the larger area brings about a reduction in power density, the thermal gradient and temperature distribution in each resonator are more uneven, resulting in the resonator at high power. Under the input, the performance drops sharply; at the same time, the increase in area also causes the resonator rigidity to deteriorate, which aggravates the resonator's deformation under stress, which leads to a decrease in the resonator's Q value, which ultimately causes device performance degradation, poor stability, and shortened life. The overall size of the filter is too large and other issues; and the pure parallel split method will make the area of each sub-resonator smaller, making the perimeter area ratio of the resonator too large, resulting in an increase in the energy loss rate of each resonator. Thus reducing the Q value of each resonator will also affect the performance of the resonator. Therefore, in order to overcome the above-mentioned problems, the present invention adopts a circuit configuration mode combined in parallel and series splitting mode, so that the area of each sub-resonator is moderate, and at the same time, the power capacity of the resonator is improved.

The above are only the preferred embodiments of the present invention. It should be pointed out that for those of ordinary skill in the art, without departing from the technical principles of the present invention, several improvements and retouches can be made, and these improvements and retouches should also be It is regarded as the protection scope of the present invention.

Claims

A split structure resonator, characterized in that the split structure resonator is a resonator group composed of several sub-resonators, and the equivalent impedance of the resonator group is equal to the impedance of the original single resonator; There is only an electrical connection between two adjacent sub-resonators, while acoustically maintaining isolation; each of the sub-resonators includes a lower electrode, a piezoelectric layer, and an upper electrode.
The split structure resonator according to claim 1, wherein two pins are provided on the resonator group, and the two pins occupy the first potential point and the second potential point, respectively, and Connect with other electronic components.
The split structure resonator according to claim 1, wherein the upper electrode and/or the lower electrode of the sub-resonator are electrically connected to the upper electrode and/or the lower electrode of the adjacent sub-resonator.
A split structure resonator according to claim 1, wherein the C axis of the piezoelectric layer of the sub-resonator points from one potential point to another potential point.
A split structure resonator according to claim 4, characterized in that: the C axis of a part of the piezoelectric layer of the resonator can be directed from the first potential point to the second potential point; the C axis of the other part of the piezoelectric layer of the resonator can be The second potential point points to the first potential point.
A split structure resonator according to claim 1, characterized in that: the circuit of the resonator group is composed of several units connected in series; n units (n>1) are connected in parallel in each unit The sub-resonators and/or the circuit are connected in series with m (m>1) units.
A split structure resonator according to claim 4, 5 or 6, characterized in that: the unit has a certain piezoelectric layer of the resonator'C-axis pointing configuration', the C-axis pointing configuration requirement: The C axis of a certain sub-resonator and the other sub-resonators in the unit point in the same direction or the C axis of at least one of the sub-resonators in the unit and the other sub-resonators point in the opposite direction.
A split structure resonator according to claim 7, characterized in that a certain unit has a certain'unit C-axis configuration' relationship with the remaining units, and the relationship requires: a certain unit It has the same unit C-axis constitution relationship with the rest of the units or a certain unit has at least one unit with the opposite unit C-axis constitution relationship.
A split structure resonator according to claim 6, wherein the unit is formed by connecting at least two adjacent sub-resonators in parallel and in series with at least one other sub-resonator.
A split structure resonator according to claim 4, 5 or 9, characterized in that: the unit has a certain resonator piezoelectric layer'C-axis pointing configuration', the C-axis pointing configuration requirement: the The C-axis of a sub-resonator and the other sub-resonators in the unit point in the same direction or the C-axis of at least one of the sub-resonators in the unit and the other sub-resonators point in the opposite direction.
A split structure resonator according to claim 10, characterized in that a certain unit has a certain'unit C-axis configuration' relationship with the rest of the units, and the relationship requires: a certain unit It has the same unit C-axis constitution relationship with the rest of the units or a certain unit has at least one unit with the opposite unit C-axis constitution relationship.
A split structure resonator according to claim 1 or 3, wherein the upper electrode and the lower electrode are made of metal, a multi-layer composite material or alloy of metal; the metal includes at least the following One: molybdenum, ruthenium, gold, magnesium, aluminum, tungsten, titanium, chromium, iridium, osmium.
The split structure resonator according to claim 1, wherein the material of the piezoelectric layer includes at least one of the following: aluminum nitride, zinc oxide, lead zirconate titanate (PZT), the pressure Doping rare earth elements in electrical materials.