WO2022152178A1

WO2022152178A1 - Filter, multiplexer, and electronic device

Info

Publication number: WO2022152178A1
Application number: PCT/CN2022/071653
Authority: WO
Inventors: 边子鹏; 庞慰
Original assignee: 诺思(天津)微系统有限责任公司
Priority date: 2021-01-13
Filing date: 2022-01-12
Publication date: 2022-07-21
Also published as: CN113162578A; CN113162578B

Abstract

Disclosed in the present invention are a filter, a duplexer, a multiplexer, and an electronic device. In the embodiments of the present invention, at least two resonators in a filter have a dual-layer bottom electrode structure, and an electrical isolation trench is provided on a first bottom electrode of at least one resonator, such that an MIM capacitor is formed between the first bottom electrode and a second bottom electrode of the resonator, and the MIM capacitor is integrated at a specific position of the filter having a ladder-shaped structure by means of a specific connection manner, thus an integrated capacitor filter chip is implemented without increasing layers and the area of the chip.

Description

Filters, Multiplexers, and Electronics

technical field

The present invention relates to the technical field of filters, and in particular, to a filter, a multiplexer and an electronic device.

Background technique

In recent years, with the rapid development of the communication market, wireless communication terminals and equipment are constantly developing in the direction of miniaturization, multi-mode and multi-frequency bands, and the requirements for filter performance are getting higher and higher, mainly reflected in the lower insertion loss, wider bandwidth, higher out-of-band rejection and roll-off. The filter design with relatively wide bandwidth requires a resonator with a high electromechanical coupling coefficient, but the high electromechanical coupling coefficient resonator is not conducive to the realization of the high roll-off characteristic of the filter. Cascading capacitors can improve the roll-off characteristics of the filter, making it meet the requirements of wide bandwidth and high roll-off at the same time.

As shown in the prior art US9608595B1, insert finger capacitors are added in parallel at both ends of the reflector of the surface acoustic wave resonator to form a narrow-band filter; as shown in the prior art US10476481B1, an integrated capacitor filter chip is made by using the existing process layer. . The above two design methods add the capacitor on the layout plane structure, occupying a certain chip area, which is not conducive to the miniaturization design of the device, and increases the manufacturing cost to a certain extent.

SUMMARY OF THE INVENTION

In view of this, the present invention provides a filter, a multiplexer, and an electronic device that help to improve nonlinear performance. The present invention provides the following technical solutions:

A filter, the filter includes a plurality of resonators, the bottom electrodes of at least two of the resonators include a first bottom electrode, an isolation layer and a second bottom electrode sequentially stacked from bottom to top, the first bottom electrode The edge of the electrode and the edge of the second bottom electrode are electrically connected, and the first bottom electrode in at least one of the resonators has an electrical isolation trench, and the electrical isolation trench separates the first bottom electrode. The island region and the first bottom electrode edge region are isolated for the first bottom electrode.

Optionally, the isolation layer is an air cavity or a dielectric layer.

Optionally, the thickness of the air cavity is 0.05 μm to 3 μm.

Optionally, the thickness of the air cavity is 0.01 μm to 5 μm.

Optionally, the width of the electrical isolation trench is 0.5um to 15um.

Optionally, the shape of the first bottom electrode isolation island is the same as the shape of the effective area of the resonator.

Optionally, the shape of the first bottom electrode isolation island region is a circle or a polygon.

Optionally, the at least two resonators are all resonators in the filter.

Optionally, the first bottom electrode isolation island is connected to the pad under the substrate through a first metal connection via, and then connected to the circuit node of the filter through a wiring layer and/or other metal connection vias superior.

Optionally, the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the resonator R1 and the resonator R2 pass through the top electrode Electrically connected to each other, the first bottom electrode isolation island of the resonator R1 and the first bottom electrode of the resonator R2 are connected to their respective pads through the first metal connection vias, and then the two are connected through the wiring layer. The pads are connected.

Optionally, the number of resonators with electrical isolation trenches is multiple, the plurality of resonators with electrical isolation trenches are electrically connected to each other through the top electrode, and the plurality of resonators with electrical isolation trenches are electrically connected to each other. The first bottom electrode isolation island regions are respectively connected to the pads under the substrate through the first metal connection vias, and then connected to each other through the wiring layers under the substrate.

Optionally, the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the top electrode of the resonator R1 and the resonator R2 The bottom electrodes of the resonator R1 are electrically connected to each other through the second metal connection vias, and the first bottom electrode of the resonator R1 isolates the island region and the first bottom electrode of the resonator R2 are connected to their respective through the first metal connection vias. The pads are connected, and then the two pads are connected through the wiring layer.

Optionally, the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the top electrode of the resonator R1 and the resonator R2 The top electrode of the resonator R1 is electrically connected through the top electrode metal layer, the first bottom electrode isolation island of the resonator R1 is connected to the pad of the resonator R1 through the first metal connection via hole, and an inductor is arranged on the wiring layer and one end of it is connected to the pad of the resonator R1. The pad of the resonator R1 is connected to each other, the resonator R1 and the resonator R2 are both connected to the external circuit through the bottom electrode, and the pad of the resonator R2 is connected to the ground.

Optionally, the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the second bottom electrode of the resonator R1 and the resonator The second bottom electrode of R2 is electrically connected through the second bottom electrode metal layer, and the first bottom electrode of the resonator R1 isolates the island region through the first metal connection via hole with the inductance coil provided on the wiring layer. The first end is connected, the second end of the inductor coil is grounded, and the resonator R1 and the resonator R2 are both connected to the external circuit through the top electrode metal layer.

Optionally, the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the first bottom electrode isolation island region of the resonator R1 passes through The first metal connection via is connected to the pad, and is connected to the first bottom electrode of the resonator R2 through the wiring layer and the first metal connection via, so as to be connected between the resonator R1 and the resonator R2. A capacitor is cascaded between them.

A multiplexer includes the filter of the present invention.

An electronic device includes the filter of the present invention.

Some or all of the resonators in the present invention have a double-layer bottom electrode structure, wherein an electrical isolation trench exists on the first bottom electrode on at least one resonator, and the electrical isolation trench divides the first bottom electrode into the first bottom electrode The island region and the edge region of the first bottom electrode are isolated, so that a MIM capacitor is formed between the first bottom electrode isolation island region and the second bottom electrode of the resonator, and then integrated into the ladder structure filter through a specific connection method. The specific location of the filter enables an integrated capacitive filter chip without adding more layers and chip area. It has the advantages of good flexibility and low production cost.

Description of drawings

The accompanying drawings are used for better understanding of the present invention and do not constitute an improper limitation of the present invention. in:

1(a) and FIG. 1(b) are respectively a top view and a PP' cross-sectional view of a resonator structure with an electrical isolation trench related to an embodiment of the present invention;

Figures 2(a) and 2(b) are schematic views of the first bottom electrode of the resonator with electrical isolation trenches in an embodiment of the present invention;

Fig. 3 (a), Fig. 3 (b), Fig. 3 (c) are respectively the top view, PP' cross-sectional view and equivalent circuit diagram of the first resonator structure in the embodiment of the present invention;

4(a), FIG. 4(b), and FIG. 4(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the second resonator structure in the embodiment of the present invention;

5(a), FIG. 5(b), and FIG. 5(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the third resonator structure in the embodiment of the present invention;

Fig. 6 (a), Fig. 6 (b), Fig. 6 (c), Fig. 6 (d) are respectively the top view, PP' sectional view, equivalent circuit diagram and bottom view of the fourth resonator structure in the embodiment of the present invention;

7(a), FIG. 7(b), and FIG. 7(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the fifth resonator structure in the embodiment of the present invention;

8(a), 8(b), and 8(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the sixth resonator structure in the embodiment of the present invention;

9(a), FIG. 9(b), and FIG. 9(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the seventh resonator structure in the embodiment of the present invention;

Fig. 10(a) is a circuit structure diagram of the first embodiment of the present invention, and Fig. 10(b) is a schematic diagram showing the comparison of insertion loss frequency characteristics corresponding to Fig. 10(a);

Fig. 11(a) is a circuit structure diagram of the second embodiment of the present invention, and Fig. 11(b) is a schematic diagram showing the comparison of the insertion loss frequency characteristics corresponding to Fig. 11(a);

Fig. 12(a) is a circuit structure diagram of a third embodiment of the present invention, and Fig. 12(b) is a schematic diagram showing the comparison of insertion loss frequency characteristics corresponding to Fig. 12(a);

FIG. 13( a ) is a circuit structure diagram of a fourth embodiment of the present invention, and FIG. 13( b ) is a schematic diagram showing the comparison of the insertion loss frequency characteristics corresponding to FIG. 13( a ).

Among them, the meanings of each label are as follows:

20-pad or wiring layer, 21-first metal connection via, 22-substrate, 23-first bottom electrode, 24-isolation layer, 25-second bottom electrode, 26-piezoelectric film layer, 27- Top electrode, 28 - Electrical isolation trench, 29 - Top electrode connecting edge.

Detailed ways

In order for those skilled in the art to better understand the present invention, the principles of the invention are first described in detail.

In this embodiment of the present invention, the resonator in the filter adopts the form of a double-layer bottom electrode, which may be a single-layer bottom electrode for some resonators, and a double-layer bottom electrode for some resonators (and at least two resonators), or All resonators have a double-layer bottom electrode structure. The double-layer bottom electrode includes a first bottom electrode, an isolation layer and a second bottom electrode stacked in sequence from bottom to top. The first bottom electrode and the second bottom electrode are electrically connected to the edge of the resonator. connect. There is an electrical isolation trench on the first bottom electrode of at least one resonator, so that a metal-insulator-metal MIM (Metal-Insulator-Metal) is formed between the first bottom electrode and the second bottom electrode of the resonator The capacitor is then integrated in a specific position of the ladder structure filter through a specific connection method, so as to realize the integrated capacitor filter chip without increasing more layers and chip area.

FIG. 1( a ) and FIG. 1( b ) are respectively a top view and a PP' cross-sectional view of the first resonator structure in the embodiment of the present invention. As shown in the figure, the filter includes two resonators R1 and R2, both of which are designed as double-layer bottom electrode resonators, that is, the bottom electrode of the resonator includes a first bottom electrode, an isolation layer and a second bottom electrode stacked in sequence from bottom to top. Two bottom electrodes, the first bottom electrode and the second bottom electrode are electrically connected at the edge of the resonator, and the first bottom electrode is connected to one end of the first metal connection via which is electrically connected through the substrate, and the first metal connection via is connected to the other end. One end is connected to a pad under the substrate. Among them, the first bottom electrode 23 in the left resonator R1 is provided with an electrical isolation trench, and the electrical isolation trench divides the first bottom electrode into a first bottom electrode isolation island area and a first bottom electrode edge area; in the figure There is no electrical isolation trench in the first bottom electrode 23 of the resonator R2 on the right. Since the first bottom electrode isolation island region is formed by the electrical isolation trench in R1, a MIM capacitor is formed between the first bottom electrode isolation island region in R1 and the second bottom electrode 25, and the capacitance value of the capacitor is the same as that of the second bottom electrode 25. The isolated island region of the first bottom electrode is related to the facing area of the second bottom electrode and the material and thickness of the isolation layer. The capacitor is integrated in a specific position of the filter through a specific connection method, which can improve the performance of the filter without adding more layers and chip area. The thickness of the isolation layer is t, the relative dielectric constant of the isolation layer material is εr, and the area S facing the first bottom electrode isolation island region and the second bottom electrode, then the capacitance value of the MIM capacitor C=ε0×εr×S/t .

The filter of the embodiment of the present invention may be a ladder structure filter, which includes a plurality of series resonators and a plurality of parallel resonators, the series resonators are connected between the input port and the output port, and the parallel branch is connected to the series branch. between a node and ground.

In the filter of the embodiment of the present invention, the isolation layer is an air cavity or a dielectric layer. When the isolation layer is an air cavity, it not only has an isolation effect but also has an acoustic mirror effect. The thickness of the air cavity may be 0.01 μm to 5 μm. Further optionally, the thickness of the air cavity is 0.05 μm to 3 μm. This results in an ideal range of selectable capacitances.

In the filter of the embodiment of the present invention, the shape of the first bottom electrode isolation region is the same as the shape of the effective area of the resonator. The first bottom electrode with the electrical isolation trenches may be as shown in FIG. 2(a) or FIG. 2(b). 21 is the first metal connection via hole, the first bottom electrode isolation island region shown at 50 is not electrically connected to the second bottom electrode, and the first bottom electrode edge region shown at 51 is electrically connected to the second bottom electrode. As shown, the shape of the first bottom electrode isolation island region 50 may be a circle or a polygonal portion. In addition, the first bottom electrode isolation island region 50 can also be any other shape. Changing the position or width of the electrical isolation trench can affect the area of the first bottom electrode isolation island, thereby affecting the change of the facing area S between the first bottom electrode isolation island and the second bottom electrode, and finally the MIM capacitance will vary with change.

In the filter of the embodiment of the present invention, the corresponding MIM capacitor in the resonator with the electrical isolation trench is integrated in a specific position of the filter through a specific connection method, and several specific examples are given for detailed description below.

3(a), 3(b), and 3(c) are a top view, a PP' cross-sectional view, and an equivalent circuit diagram of the first resonator structure in an embodiment of the present invention, respectively. As shown, R1 is a resonator with electrical isolation trenches and R2 is a resonator without electrical isolation trenches. The resonator R1 and the resonator R2 are electrically connected to each other through the top electrode, and the first bottom electrode isolation island region of the resonator R1 and the first bottom electrode of the resonator R2 are both connected to the pad through the first metal connection via hole, and then connect to the pad through the first metal connection via hole. The wiring layer below the substrate connects the two pads. Since the pads and the wiring layers are both conductor materials, the figures are drawn as a whole, and the two pads and the wiring layers are not separately drawn, and will not be repeated if there are similar situations in other embodiments herein. Both the resonator R1 and the resonator R2 are connected to the external circuit through the bottom electrode, so that a parallel capacitor is formed between the resonator R1 and the resonator R2, and the value of the parallel capacitor is the same as that of the first bottom electrode. The facing area of the electrodes is related to the height of the cavity.

4(a), 4(b), and 4(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the second resonator structure in the embodiment of the present invention. As shown, both R1 and R2 are resonators with electrical isolation trenches. The resonator R1 and the resonator R2 are electrically connected to each other through the top electrode, and the first bottom electrode isolation island regions of the resonator R1 and the resonator R2 are connected to the pad through the first metal connection via hole, and then the above two are connected through the wiring layer. The two pads are connected to each other, so as to form two capacitors in parallel between the resonator R1 and the resonator R2. height related.

5(a), 5(b), and 5(c) are respectively a top view, a PP' cross-sectional view, and an equivalent circuit diagram of the third resonator structure in the embodiment of the present invention. R1 is a resonator with electrical isolation trenches and R2 is a resonator without electrical isolation trenches. The top electrode of the resonator R1 and the bottom electrode of the resonator R2 are electrically connected to each other through the second metal connection via 30, and the first bottom electrode isolation island region of the resonator R1 and the first bottom electrode of the resonator R2 are both connected through the first metal The vias are connected to their respective pads, and then the above two pads are connected through the wiring layer, so that a capacitor is formed in parallel at both ends of the resonator R1, and the size of the capacitor is the same as that of the first bottom electrode. The facing area of the bottom electrode is related to the height of the cavity.

6(a), 6(b), 6(c), and 6(d) are the top view, PP' cross-sectional view, equivalent circuit diagram and bottom view of the fourth resonator structure in the embodiment of the present invention, respectively. As shown in the figure, the top electrode of the resonator R1 and the top electrode of the resonator R2 are electrically connected through the top electrode metal layer, and the first bottom electrode of the resonator R1 isolates the island region and the resonator R1 through its first metal connection via hole. The pad of the resonator is connected to the wiring layer, and one end of the inductor is connected to the pad of the resonator R1. Both the resonator R1 and the resonator R2 are connected to the external circuit through the bottom electrode. As shown in FIG. 6(d), the pad P1 of the resonator R1 is connected to the first metal connection via hole below the resonator R1, and the pad P2 of the resonator R2 is connected to the ground. Therefore, a series LC resonator circuit is formed at one end of the bottom electrode of the resonator R1 (the left side of the resonator R1), and the capacitance value of the capacitor is the same as the area of the first bottom electrode and the second bottom electrode of the resonator R1. The height of the cavity is related, and the resonance frequency of the series LC resonant circuit is determined by the inductance value of the above-mentioned inductor and the above-mentioned capacitance value. A series LC resonant circuit is added between a certain node of the series path of the filter of this embodiment and the ground.

7(a), 7(b), and 7(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the fifth resonator structure in the embodiment of the present invention. As shown, R1 is a resonator with electrical isolation trenches and R2 is a resonator without electrical isolation trenches. The second bottom electrode of the resonator R1 and the second bottom electrode of the resonator R2 are electrically connected through the second bottom electrode metal layer, and the first bottom electrode of the resonator R1 isolates the island region through the first metal connection via hole and is provided on the wiring layer. The first end of the inductance coil (the end of the pad P1) is connected, the second end of the inductance coil (the end of the pad P2) is grounded, and the resonator R1 and the resonator R2 are both connected to the external circuit through the top electrode metal layer, so as to resonate The node between the resonator R1 and the resonator R2 is connected to the ground to form a series LC resonant circuit. The size of the capacitance is related to the area of the first bottom electrode isolation island of the resonator R1 facing the second bottom electrode and the height of the cavity. The resonance frequency of the series LC resonant circuit is determined by the inductance value of the above-mentioned inductor and the above-mentioned capacitance value.

8(a), 8(b), and 8(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the sixth resonator structure in the embodiment of the present invention. As shown, R1 is a resonator with electrical isolation trenches and R2 is a resonator without electrical isolation trenches. The first bottom electrode isolation island of the resonator R1 is connected to the pad through the first metal connection via hole, and is connected to the first bottom electrode of the resonator R2 through the wiring layer and the first metal connection via hole, so that the resonator R1 is in harmony. A capacitor is cascaded between the vibrators R2, and the size of the capacitor is related to the area facing the first bottom electrode isolation island region and the second bottom electrode and the height of the cavity.

9(a), 9(b), and 9(c) are respectively a top view, a PP' cross-sectional view and an equivalent circuit diagram of the seventh resonator structure in the embodiment of the present invention. In the embodiment of the present invention, the resonator R3 without the first metal connection via hole can be configured as the resonator structure with a single-layer bottom electrode as shown in the figure. This example illustrates the case where not all resonators in the filter employ a double bottom electrode. In addition, the air cavity under the single-layer bottom electrode can also be omitted.

The filter of the embodiment of the present invention can improve the far-band suppression characteristic of the filter without increasing the chip area. The following description is combined with the experimental test. The circuit structure of each embodiment is only an exemplary description, and the specific structure (including the order, the split form of the resonator, the way of connecting parallel branches to the ground, and the structure of the matching network, etc.) is not limited.

Comparison test 1

FIG. 10( a ) is a circuit structure diagram of the first embodiment of the present invention, and FIG. 10( b ) is a schematic diagram showing the comparison of the insertion loss frequency characteristics corresponding to FIG. 11( a ).

In FIG. 10( a ), a ladder-type structure filter composed of series resonators Se_1 to Se_3 and parallel resonators Sh_1 to Sh_4 is shown. T1 is the signal input port, T2 is the signal output port, L1 and L2 are the series inductance of the input terminal and the series inductance of the output terminal, and L3 and L4 are the grounding inductance of the parallel branch. In the first embodiment of the present invention, in this circuit structure, a parallel capacitor is integrated at both ends of the series resonator Se_2. Specifically, the capacitor can be integrated in the manner shown in FIG. 5( a ) to FIG. 5( c ). The first comparative example does not use the integrated parallel capacitor structure, except that the topology of the first comparative example is the same as that of the first embodiment.

In Figure 10(b), taking a filter with a passband of 2515MHz-2675MHz (relative bandwidth of 6.16%) as an example, the thick solid line is the insertion loss frequency characteristic curve of the first embodiment of the present invention, and the thin solid line is the first comparative example The insertion loss frequency characteristic curve, because the first embodiment adopts the integrated parallel capacitor structure, a capacitor is connected in parallel at both ends of the resonator Se_2 in the equivalent series branch, so that its equivalent electromechanical coupling coefficient becomes smaller, so that the filter can pass through. The roll-off characteristics on the right side of the belt are effectively improved.

In addition, if the structure shown in Fig. 3(a) to Fig. 3(c), the structure shown in Fig. 4(a) to Fig. 4(c), or the structure shown in Fig. 8(a) to Fig. 8(c) is applied to the series branch With the structure shown, a similar device performance improvement effect can also be achieved.

Comparison test 2

FIG. 11( a ) is a circuit structure diagram of a second embodiment of the present invention, and FIG. 11( b ) is a schematic diagram showing the comparison of the insertion loss frequency characteristics corresponding to FIG. 11( a ).

In FIG. 11( a ), a ladder-type piezoelectric filter is composed of series resonators Se_1 to Se_3 and parallel resonators Sh_1 to Sh_5. T1 is the signal input port, T2 is the signal output port, L1 and L2 are the series inductance of the input terminal and the series inductance of the output terminal, and L3 and L4 are the grounding inductance of the parallel branch. In this circuit structure, the parallel resonator Sh_4 and the parallel resonator Sh_5 are connected in series to form a parallel branch of the filter, and in the second embodiment, a capacitor is also integrated, as shown in Figure 4(a) to Figure 4(c) In the manner shown, two capacitors in series are formed in parallel at both ends of the parallel resonator Sh_4 and the parallel resonator Sh_5.

In Fig. 11(b), taking a filter with a passband of 2515MHz-2675MHz (relative bandwidth of 6.16%) as an example, the thick solid line is the insertion loss frequency characteristic curve of the second embodiment of the present invention, and the thin solid line is the first comparative example In the insertion loss frequency characteristic curve, since a capacitor is connected in parallel at both ends of the resonator Sh_4 and the resonator Sh_5 in the equivalent fourth parallel branch in the second embodiment, the equivalent electromechanical coupling coefficient of the parallel branch is reduced, so that it can be The roll-off characteristic on the right side of the filter passband is effectively improved.

In addition, if the structure shown in Fig. 3(a) to Fig. 3(c), the structure shown in Fig. 5(a) to Fig. 5(c) or the structure shown in Fig. 8(a) to Fig. 8(c) is applied to the series branch With the structure shown, a similar device performance improvement effect can also be achieved.

Comparison test 3

FIG. 12( a ) is a circuit structure diagram of a third embodiment of the present invention, and FIG. 12( b ) is a schematic diagram showing the comparison of the insertion loss frequency characteristics corresponding to FIG. 12( a ).

In FIG. 12( a ), a ladder-type piezoelectric filter is composed of series resonators Se_1 to Se_3 and parallel resonators Sh_1 to Sh_4 . T1 is the signal input port, T2 is the signal output port, L1 and L2 are the series inductance of the input terminal and the series inductance of the output terminal, and L3 and L4 are the grounding inductance of the parallel branch. The second bottom electrode of the series resonator Se_4 is connected to the bottom electrode of the series resonator Se_3, and the isolated part of the first bottom electrode of the series resonator Se_4 is connected to the parallel branch close to the signal input port through the first metal connection via and the wiring layer, Therefore, a cross-coupling capacitor is formed between the series resonator Se_4 close to the signal output end and the parallel branch close to the signal input port, which is beneficial to improve the filter's entry and stop band suppression characteristics. The second comparative example is relative to the third embodiment, the series resonator se4 has no electrical isolation trench, and its first bottom electrode is not electrically connected to the parallel resonator sh2.

In FIG. 12( b ), the thick solid line is the insertion loss frequency characteristic curve of the third embodiment of the present invention, and the thin solid line is the insertion loss frequency characteristic curve of the second comparative example. As shown in Figure 12(b), compared with the second comparative example, the forward-stop-band suppression of the third embodiment is significantly improved, and the out-of-band suppression at the high frequency end, especially in the N79 (4400MHz-5000MHz) frequency band, is improved by about 15dB.

Comparison test 4

In FIG. 13( a ), a ladder-type piezoelectric filter is formed by series resonators Se_1 to Se_4 and parallel resonators Sh_1 to Sh_4 . T1 is the signal input port, T2 is the signal output port, L1 and L2 are the series inductance of the input terminal and the series inductance of the output terminal, and L3 and L4 are the grounding inductance of the parallel branch. In the fourth embodiment, for this circuit structure, a series LC resonant circuit is formed from the node between the series resonator Se_3 and the series resonator Se_4 to the ground, that is, the circuit shown in FIG. 6(a) to FIG. 6(d) is adopted. The integrated LC series resonant circuit structure of the present invention is shown. The third comparative example has the same topology as the fourth embodiment except that there is no LC series resonant circuit.

In FIG. 13( b ), the thick solid line is the insertion loss frequency characteristic curve of the circuit of the fourth embodiment of the present invention, and the thin solid line is the insertion loss frequency characteristic curve of the third comparative example circuit of the present invention. Since the structures shown in FIGS. 6(a) to 6(d) are added to the fourth embodiment, the node between the equivalent series resonator Se_3 and the series resonator Se_4 forms a series LC resonant circuit, and the series LC resonator circuit is connected to the ground. The resonant frequency of the circuit is set around 9GHz. Compared with the fourth comparative example, the out-of-band suppression characteristic of the structure filter of the fourth embodiment is improved to different degrees in the 8GHz-10GHz frequency band, and the out-of-band suppression improvement at the 9GHz frequency point can reach about 20dB.

To sum up, the resonator in the filter of the embodiment of the present invention utilizes the existing thin film bulk acoustic wave resonator manufacturing process to realize the integrated capacitance and inductance of the thin film bulk acoustic wave filter without adding redundant layers, and improves the rolling performance of the filter. drop and out-of-band rejection characteristics; the design does not increase chip area, increases design flexibility, reduces chip size, and reduces production costs.

The duplexer, the multiplexer, and the electronic device of the embodiments of the present invention include the filters of the embodiments of the present invention.

The material selection range of the structure involved in the present invention is as follows:

20: is the metal layer under the substrate, which can be used for wiring or realizing signal line pads.

21: The first metal connection via hole can be selected from metals such as gold, aluminum, magnesium, tungsten, and copper.

22: Substrate, optional materials are single crystal silicon, gallium arsenide, sapphire, quartz, etc.

23: The first bottom electrode, the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium and other metals.

24: Acoustic mirror, this figure shows a cavity. The cavity height is between 0.05um and 3um.

25: The second bottom electrode, the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium and other metals.

26: Piezoelectric thin film layer, which can be selected from single crystal aluminum nitride, polycrystalline aluminum nitride, zinc oxide, PZT and other materials and contains rare earth element doping materials with a certain atomic ratio of the above materials.

27: Top electrode, the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium and other metals, and the top electrode includes a mass load layer.

28: Electrical isolation trenches.

29: The top electrode connection side, the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium and other metals.

The above-mentioned specific embodiments do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions may occur depending on design requirements and other factors. Any modifications, equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

A filter comprising a plurality of resonators, wherein the bottom electrodes of at least two of the resonators include a first bottom electrode, an isolation layer and a second bottom electrode sequentially stacked from bottom to top, so The edge of the first bottom electrode and the edge of the second bottom electrode are electrically connected, and the first bottom electrode in at least one of the resonators has an electrical isolation trench, and the electrical isolation trench separates the second bottom electrode. A bottom electrode is divided into a first bottom electrode isolation island region and a first bottom electrode edge region.
The filter according to claim 1, wherein the isolation layer is an air cavity or a dielectric layer.
The filter according to claim 2, wherein the thickness of the air cavity is 0.05 μm to 3 μm.
The filter according to claim 2, wherein the thickness of the air cavity is 0.01 μm to 5 μm.
The filter according to claim 2, wherein the width of the electrical isolation trench is 0.5um to 15um.
The filter according to claim 1, wherein the shape of the first bottom electrode isolation island is the same as the shape of the effective area of the resonator.
The filter according to claim 6, wherein the shape of the first bottom electrode isolation island region is a circle or a polygon.
The filter according to claim 1, wherein the at least two resonators are all the resonators in the filter.
The filter according to any one of claims 1 to 8, wherein the first bottom electrode isolation island is connected to the pad under the substrate through a first metal connection via hole, and is then connected to the pad under the substrate through a first metal connection via hole. and/or other metal connection vias to the circuit nodes of the filter.
The filter of claim 9, wherein the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the resonator R1 and the resonator R2 are electrically connected to each other through the top electrode, and the first bottom electrode of the resonator R1 isolates the island region and the first bottom electrode of the resonator R2 through the first metal connection vias to their respective soldering holes. The pads are connected, and then the two pads are connected through a wiring layer.
The filter according to claim 9, wherein the number of resonators with electrical isolation trenches is plural, and the plurality of resonators with electrical isolation trenches are electrically connected to each other through top electrodes, and the plurality of resonators with electrical isolation trenches are electrically connected to each other through top electrodes. The first bottom electrode isolation island regions of the resonators with electrical isolation trenches are respectively connected to the pads under the substrate through the first metal connection vias, and then connected to each other through the wiring layers under the substrate.
The filter of claim 9, wherein the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the resonator The top electrode of R1 and the bottom electrode of the resonator R2 are electrically connected to each other through a second metal connection via hole, and the first bottom electrode isolation island region of the resonator R1 and the first bottom electrode of the resonator R2 pass through each other. The first metal connection vias are connected to the respective pads, and then the two pads are connected through the wiring layer.
The filter of claim 9, wherein the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the resonator The top electrode of R1 and the top electrode of the resonator R2 are electrically connected through the top electrode metal layer, and the first bottom electrode isolation island of the resonator R1 is connected to the pad of the resonator R1 through the first metal connection via hole. The wiring layer is provided with an inductor and one end of the inductor is connected to the pad of the resonator R1. Both the resonator R1 and the resonator R2 are connected to the external circuit through the bottom electrode, and the pad of the resonator R2 is connected to the ground.
The filter of claim 9, wherein the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the resonator The second bottom electrode of R1 and the second bottom electrode of the resonator R2 are electrically connected through the second bottom electrode metal layer, and the first bottom electrode of the resonator R1 is isolated from the island region through the first metal connection via hole. The first end of the inductor coil provided on the wiring layer is connected to the ground, the second end of the inductor coil is grounded, and the resonator R1 and the resonator R2 are both connected to the external circuit through the top electrode metal layer.
The filter of claim 9, wherein the filter includes a resonator R1 with the electrical isolation trench and a resonator R2 without the electrical isolation trench, wherein the resonator The first bottom electrode isolation island region of R1 is connected to the pad through the first metal connection via hole, and is connected to the first bottom electrode of the resonator R2 through the wiring layer and the first metal connection via hole, A capacitor is thus cascaded between the resonator R1 and the resonator R2.
A multiplexer comprising the filter according to any one of claims 1 to 15.
An electronic device comprising the filter according to any one of claims 1 to 15.