CN113644895B - Thin film bulk acoustic resonator filter and filter assembly - Google Patents
Thin film bulk acoustic resonator filter and filter assembly Download PDFInfo
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- CN113644895B CN113644895B CN202110743238.3A CN202110743238A CN113644895B CN 113644895 B CN113644895 B CN 113644895B CN 202110743238 A CN202110743238 A CN 202110743238A CN 113644895 B CN113644895 B CN 113644895B
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- 239000010409 thin film Substances 0.000 title claims abstract description 186
- 239000010408 film Substances 0.000 claims abstract description 138
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- 238000004891 communication Methods 0.000 description 3
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- 239000000463 material Substances 0.000 description 3
- 238000010897 surface acoustic wave method Methods 0.000 description 3
- 239000000919 ceramic Substances 0.000 description 2
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- 238000002360 preparation method Methods 0.000 description 2
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- 230000009286 beneficial effect Effects 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/56—Monolithic crystal filters
- H03H9/564—Monolithic crystal filters implemented with thin-film techniques
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/56—Monolithic crystal filters
- H03H9/566—Electric coupling means therefor
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/58—Multiple crystal filters
- H03H9/582—Multiple crystal filters implemented with thin-film techniques
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/54—Filters comprising resonators of piezoelectric or electrostrictive material
- H03H9/58—Multiple crystal filters
- H03H9/60—Electric coupling means therefor
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Abstract
The invention relates to the technical field of filters, and provides a film bulk acoustic resonator filter and a filter assembly, wherein the filter comprises an input terminal, an output terminal, a plurality of film bulk acoustic resonators connected in series and a plurality of film bulk acoustic resonators connected in parallel; the plurality of thin film bulk acoustic resonators connected in series include a first thin film bulk acoustic resonator to a fourth thin film bulk acoustic resonator connected in series between an input terminal and an output terminal; the plurality of parallel thin film bulk acoustic resonators comprise a fifth thin film bulk acoustic resonator, a sixth thin film bulk acoustic resonator and a seventh thin film bulk acoustic resonator, one ends of the fifth thin film bulk acoustic resonator, the sixth thin film bulk acoustic resonator and the seventh thin film bulk acoustic resonator are respectively connected to nodes between two adjacent thin film bulk acoustic resonators in the plurality of series thin film bulk acoustic resonators, and the other ends of the fifth thin film bulk acoustic resonator, the sixth thin film bulk acoustic resonator and the seventh thin film bulk acoustic resonator are respectively connected to a grounding terminal. The filter may allow signals of a specific frequency to pass.
Description
Technical Field
The invention belongs to the technical field of filters, and particularly relates to a thin film bulk acoustic resonator filter and a filter assembly.
Background
In recent years, with the continuous development of 5G wireless communication technology, mobile communication is realized by using higher frequency bands and frequency band recombination, which puts higher demands on miniaturization, high frequency bandwidth, integration and flexibility of related radio frequency components.
The film bulk acoustic resonator (Film Bulk Acoustic Resonator, FBAR) filter is gradually replacing the traditional surface acoustic wave filter and ceramic filter by virtue of its excellent characteristics of small size, high resonant frequency, high quality factor, large power capacity, good roll-off effect, etc., and has an increasing market share in the field of radio frequency filters and plays a great role in the field of 5G wireless communication radio frequency.
However, most of the current researches on the thin film bulk acoustic resonator filter are focused on the preparation method, and few researches on the specific structure of the thin film bulk acoustic resonator filter are performed.
Disclosure of Invention
The embodiment of the invention provides a film bulk acoustic resonator filter and a filter assembly, and aims to provide a novel structure of the film bulk acoustic resonator filter.
In a first aspect, an embodiment of the present invention provides a thin film bulk acoustic resonator filter having a center frequency of 1805MHz, including an input terminal, an output terminal, a plurality of thin film bulk acoustic resonators connected in series, and a plurality of thin film bulk acoustic resonators connected in parallel;
the plurality of thin film bulk acoustic resonators connected in series comprise a first thin film bulk acoustic resonator, a second thin film bulk acoustic resonator, a third thin film bulk acoustic resonator and a fourth thin film bulk acoustic resonator, and are connected in series between an input terminal and an output terminal;
the plurality of parallel thin film bulk acoustic resonators comprise a fifth thin film bulk acoustic resonator, a sixth thin film bulk acoustic resonator and a seventh thin film bulk acoustic resonator, wherein one ends of the fifth thin film bulk acoustic resonator, the sixth thin film bulk acoustic resonator and the seventh thin film bulk acoustic resonator are respectively connected to nodes between two adjacent thin film bulk acoustic resonators in the plurality of series thin film bulk acoustic resonators; the other ends of the fifth film bulk acoustic resonator, the sixth film bulk acoustic resonator and the seventh film bulk acoustic resonator are respectively connected with a grounding terminal;
the plurality of parallel thin film bulk acoustic resonators further comprises a first parallel arm resonator, a second parallel arm resonator and a third parallel arm resonator; the first parallel-arm resonator includes a fifth thin film bulk acoustic resonator, the second parallel-arm resonator includes a sixth thin film bulk acoustic resonator, and the third parallel-arm resonator includes a seventh thin film bulk acoustic resonator.
The filter in the embodiment of the invention comprises a plurality of film bulk acoustic resonators connected in series between an input terminal and an output terminal, and a plurality of film bulk acoustic resonators connected in parallel between a plurality of film bulk acoustic resonator nodes connected in series. The signal passes through the input terminal, and then passes through the thin film bulk acoustic resonators connected in series and the thin film bulk acoustic resonators connected in parallel, so that the signal with a specific frequency can pass through.
With reference to the first aspect, in one possible implementation manner, a series resonance frequency and a parallel resonance frequency of the plurality of thin film bulk acoustic resonators connected in series are the same; the series resonant frequency and the parallel resonant frequency of the plurality of parallel thin film bulk acoustic resonators are the same.
With reference to the first aspect, in one possible implementation manner, a series resonant frequency of the plurality of thin film bulk acoustic resonators connected in series is the same as a parallel resonant frequency of the plurality of thin film bulk acoustic resonators connected in parallel.
With reference to the first aspect of the present invention,in one possible implementation, the area of the first thin film bulk acoustic resonator is 21300 μm 2 -21500μm 2 The second film bulk acoustic resonator has an area of 10700 μm 2 -10900μm 2 The third film bulk acoustic resonator has an area of 10100 μm 2 -10300μm 2 The fourth film bulk acoustic resonator has an area of 25200 μm 2 -25400μm 2 The fifth thin film bulk acoustic resonator has an area of 29500 μm 2 -29700μm 2 The area of the sixth thin film bulk acoustic resonator is 37000 μm 2 -37200μm 2 The seventh thin film bulk acoustic resonator has an area of 23400 μm 2 -23600μm 2 。
With reference to the first aspect, in one possible implementation manner, the thin film bulk acoustic resonator filter includes a piezoelectric layer, and a layout of the thin film bulk acoustic resonator filter mainly includes a sacrificial layer, a lower electrode layer, an upper electrode layer, a difference frequency layer and a hole layer, where the difference frequency layer corresponds to a plurality of parallel thin film bulk acoustic resonators, and the plurality of series thin film bulk acoustic resonators do not have a difference frequency layer; a plurality of release holes are formed in the hole layer, each film bulk acoustic resonator is provided with a plurality of release channels, and each release channel corresponds to at least one release hole.
In this embodiment, the thicknesses of the upper electrode layer and the lower electrode layer areThe thickness of the piezoelectric layer isThe difference frequency layer has a thickness of->The diameter of the release hole is 15 μm-25 μm.
In some embodiments, the distance between the centers of the first to fourth thin film bulk acoustic resonators and the line in which the input terminal and the output terminal are located is less than a threshold value, the fifth and seventh thin film bulk acoustic resonators are located on a first side of the line, and the sixth thin film bulk acoustic resonator is located on a second side of the line.
In some embodiments, the distance from the center of the first, second, third, and fourth film bulk acoustic resonators to the first line where the input and output ends are located is less than a threshold;
the central connecting lines of the first film bulk acoustic resonator, the second film bulk acoustic resonator and the fifth film bulk acoustic resonator form a first V shape, the central connecting lines of the third film bulk acoustic resonator, the fourth film bulk acoustic resonator and the seventh film bulk acoustic resonator form a second V shape, and the central connecting lines of the second film bulk acoustic resonator, the third film bulk acoustic resonator and the sixth film bulk acoustic resonator form a third V shape;
the angle of the first V-shaped and the second V-shaped is smaller than 90 degrees, and the opening directions of the first V-shaped and the second V-shaped face to the first side of the straight line; the angle of the third V-shaped sum is larger than 90 degrees, and the opening direction of the third V-shaped sum faces the second side of the straight line.
Illustratively, the layout of the filter includes a first version region to a twelfth version region;
the first plate region, the third plate region and the fourth plate region are grounded terminal plate regions, the second plate region is an input terminal plate region, the fifth plate region is an output terminal plate region, the first plate region is positioned at the lower part of the layout of the filter, and the second plate region, the fifth plate region, the third plate region and the fourth plate region are symmetrically arranged at two sides of the layout of the filter respectively;
the sixth edition of region, the seventh edition of region, the eighth edition of region and the ninth edition of region are edition of regions of the first film bulk acoustic resonator, the second film bulk acoustic resonator, the third film bulk acoustic resonator and the fourth film bulk acoustic resonator respectively; the sixth edition region, the seventh edition region, the eighth edition region and the ninth edition region are respectively connected in series between the second edition region and the fifth edition region;
the tenth plate region, the eleventh plate region and the twelfth plate region are plate regions of the fifth film bulk acoustic resonator, the sixth film bulk acoustic resonator and the seventh film bulk acoustic resonator, respectively;
the eleventh edition of region is positioned at the lower part of the seventh edition of region, one end of the eleventh edition of region is respectively connected with the seventh edition of region and the eighth edition of region, and the other end of the eleventh edition of region is connected with the first edition of region;
the tenth edition region is positioned at the upper part of the sixth edition region, one end of the tenth edition region is respectively connected with the sixth edition region and the seventh edition region, and the other end of the tenth edition region is connected with the third edition region;
the twelfth edition of region is positioned at the upper part of the eighth edition of region, one end of the twelfth edition of region is respectively connected with the eighth edition of region and the ninth edition of region, and the other end of the twelfth edition of region is connected with the fourth edition of region.
In a second aspect, an embodiment of the present invention further provides a film bulk acoustic resonator filter assembly, including a film bulk acoustic resonator filter according to any one of the preceding claims.
Drawings
FIG. 1 is a schematic circuit diagram of a film bulk acoustic resonator filter according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of a layout structure of a film bulk acoustic resonator filter according to an embodiment of the present invention;
FIG. 3 is a schematic layout of a sacrificial layer of the thin film bulk acoustic resonator filter shown in FIG. 2;
FIG. 4 is a schematic layout of the bottom electrode layer of the thin film bulk acoustic resonator filter shown in FIG. 2;
FIG. 5 is a schematic layout of the upper electrode layer of the thin film bulk acoustic resonator filter shown in FIG. 2;
FIG. 6 is a layout view of a difference frequency layer representation of the thin film bulk acoustic resonator filter shown in FIG. 2;
FIG. 7 is a schematic layout of the aperture layer of the thin film bulk acoustic resonator filter shown in FIG. 2;
fig. 8 is an amplitude-frequency characteristic curve of a film bulk acoustic resonator filter according to an embodiment of the present invention.
In the figure: 11-input terminal, 12-output terminal, X1-first film bulk acoustic resonator, X2-second film bulk acoustic resonator, X3-third film bulk acoustic resonator, X4-fourth film bulk acoustic resonator, X5-fifth film bulk acoustic resonator, X6-sixth film bulk acoustic resonator, X7-seventh film bulk acoustic resonator, 41-release hole.
Detailed Description
In order to make the technical problems, technical schemes and beneficial effects to be solved more clear, the invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
Thin film bulk acoustic resonator (Film Bulk Acoustic Resonator, FBAR) filters are gradually replacing conventional Surface Acoustic Wave (SAW) filters and ceramic filters, and are playing a great role in the radio frequency field of wireless communications. However, most of the existing researches on FBAR filters are focused on the preparation method, and the researches on specific structures are less. Some engineering application needs to use a filter with a center frequency of 1805MHz, the 1dB bandwidth is larger than 30MHz, and suppression is needed to be larger than 45dBc at 1750MHz and 1860 MHz.
Based on the above problems, embodiments of the present invention provide a thin film bulk acoustic resonator filter. The filter includes: the thin film bulk acoustic resonator comprises an input terminal, an output terminal, a plurality of thin film bulk acoustic resonators connected in series and a plurality of thin film bulk acoustic resonators connected in parallel. Wherein the plurality of series-connected film bulk acoustic resonators includes a first film bulk acoustic resonator, a second film bulk acoustic resonator, a third film bulk acoustic resonator, and a fourth film bulk acoustic resonator, connected in series between the input terminal and the output terminal. The plurality of parallel thin film bulk acoustic resonators include a fifth thin film bulk acoustic resonator, a sixth thin film bulk acoustic resonator, and a seventh thin film bulk acoustic resonator, one ends of the fifth thin film bulk acoustic resonator, the sixth thin film bulk acoustic resonator, and the seventh thin film bulk acoustic resonator are respectively connected to nodes between two adjacent thin film bulk acoustic resonators in the plurality of series thin film bulk acoustic resonators, and the other ends of the fifth thin film bulk acoustic resonator, the sixth thin film bulk acoustic resonator, and the seventh thin film bulk acoustic resonator are respectively connected to a ground terminal.
The thin film bulk acoustic resonator filter includes a plurality of thin film bulk acoustic resonators connected in series between an input terminal and an output terminal, and a plurality of thin film bulk acoustic resonators connected in parallel between a plurality of thin film bulk acoustic resonator nodes connected in series. When the signal passes through the input terminal, the signal can be filtered in a specific frequency band after passing through the thin film bulk acoustic resonators connected in series and the thin film bulk acoustic resonators connected in parallel, so that the signal with a specific center frequency is output.
Fig. 1 shows a schematic circuit diagram of a thin film bulk acoustic resonator filter according to an embodiment of the present invention. Referring to fig. 1, the thin film bulk acoustic resonator filter includes an input terminal 11, an output terminal 12, a plurality of thin film bulk acoustic resonators connected in series, and a plurality of thin film bulk acoustic resonators connected in parallel. Wherein the plurality of series connected film bulk acoustic resonators includes a first film bulk acoustic resonator X1, a second film bulk acoustic resonator X2, a third film bulk acoustic resonator X3, and a fourth film bulk acoustic resonator X4. The plurality of parallel thin film bulk acoustic resonators includes a fifth thin film bulk acoustic resonator X5, a sixth thin film bulk acoustic resonator X6, and a seventh thin film bulk acoustic resonator X7.
The thin film bulk acoustic resonators connected in parallel are divided into three parallel-arm resonators, namely a first parallel-arm resonator, a second parallel-arm resonator and a third parallel-arm resonator. The first parallel-arm resonator includes a fifth thin film bulk acoustic resonator X5, the second parallel-arm resonator includes a sixth thin film bulk acoustic resonator X6, and the third parallel-arm resonator includes a seventh thin film bulk acoustic resonator X7.
Specifically, the first thin film bulk acoustic resonator X1, the second thin film bulk acoustic resonator X2, the third thin film bulk acoustic resonator X3, and the fourth thin film bulk acoustic resonator X4 are connected in series between the input terminal 11 and the output terminal 12. And the first to fourth thin film bulk acoustic resonators X1 to X4 have the same first series resonance frequency and first parallel resonance frequency.
One end of the fifth film bulk acoustic resonator X5 is connected to a node between the first film bulk acoustic resonator X1 and the second film bulk acoustic resonator X2, and the other end is connected to a ground terminal. One end of the sixth thin film bulk acoustic resonator X6 is connected to a node between the second thin film bulk acoustic resonator X2 and the third thin film bulk acoustic resonator X3, and the other end may be directly connected to a ground terminal. One end of the seventh thin film bulk acoustic resonator X7 is connected to a node between the third thin film bulk acoustic resonator X3 and the fourth thin film bulk acoustic resonator X4, and the other end may be directly connected to a ground terminal. The fifth to seventh thin film bulk acoustic resonators X5 to X7 described above have the same second series resonance frequency and second parallel resonance frequency.
In an exemplary embodiment of the present invention, the first series resonant frequency of the plurality of series-connected thin film bulk acoustic resonators and the second parallel resonant frequency of the plurality of parallel-connected thin film bulk acoustic resonators are the same, thereby forming a specific center frequency.
In some embodiments, the area of the thin film bulk acoustic resonator should be controlled to 4000 μm in consideration of the difficulty in process implementation 2 -80000μm 2 Between them. In the same circuit, the area of each film bulk acoustic resonator in the circuit should be as small as possible when designing, and the area of each film bulk acoustic resonator in the circuit is generally smaller than 4 times.
In some embodiments, in order to obtain a specific center frequency of the thin film bulk acoustic resonator filter, it is possible to implement by adjusting the areas and positions of the first to seventh thin film bulk acoustic resonators X1 to 34. Specifically, the first thin film bulk acoustic resonator may be provided with an area of 21300 μm 2 -21500μm 2 The second film bulk acoustic resonator has an area of 10700 μm 2 -10900μm 2 The third film bulk acoustic resonator has an area of 10100 μm 2 -10300μm 2 The fourth film bulk acoustic resonator has an area of 25200 μm 2 -25400μm 2 The fifth thin film bulk acoustic resonator has an area of 29500 μm 2 -29700μm 2 The area of the sixth thin film bulk acoustic resonator is 37000 μm 2 -37200μm 2 The seventh thin film bulk acoustic resonator has an area of 23400 μm 2 -23600μm 2 . The area of the resonator is the overlapping area of the upper electrode and the lower electrode of the parallel plate capacitor of the resonator.
In some embodiments, the thin film bulk acoustic resonator filter includes a piezoelectric layer, and the layout of the thin film bulk acoustic resonator filter includes mainly a sacrificial layer, a lower electrode layer, an upper electrode layer, a difference frequency layer, and a hole layer. The difference frequency layer corresponds to a plurality of thin film bulk acoustic resonators connected in parallel, and the thin film bulk acoustic resonators connected in series do not have the difference frequency layer. The difference frequency layer is used for realizing the frequency difference between the parallel thin film bulk acoustic resonators and the series thin film bulk acoustic resonators, thereby forming a filter and realizing the filtering of the phase specific frequency. In general, the second series resonant frequency and the second parallel resonant frequency of the parallel thin film bulk acoustic resonator are lower than the first series resonant frequency and the first parallel resonant frequency of the series thin film bulk acoustic resonator, and the first series resonant frequency is equal to the second parallel resonant frequency.
In order to form an air cavity of the film bulk acoustic resonator and reflect acoustic waves, a hole layer is specially arranged, a plurality of release holes are formed in the hole layer, and each release channel of each film bulk acoustic resonator corresponds to at least one release hole.
For example, each resonator may have a plurality of release channels (e.g., five) each corresponding to one release hole, the release gas entering the release channels through the release holes and then entering the sacrificial layer regions to etch away the sacrificial layer material to a gas, which is then exhausted through the release channels and release holes. In addition, if the space of the filter is strained, the two release channels may share one release hole. In addition, in the probe test area, probes (e.g., GSG probes) are required to test the chip, so that the piezoelectric layer needs to be etched away to expose the lower electrode for testing.
In some embodiments, to obtain a filter of a particular center frequency, this may be achieved by adjusting the thicknesses of the upper electrode, lower electrode, and piezoelectric layer.
For example, to obtain a filter with a center frequency of 1805MHz, the thicknesses of the upper and lower electrode layers areThe thickness of the piezoelectric layer is +.>
In some embodiments, the difference frequency layer may have a thickness of
In some embodiments, the diameter of the release holes may be 15 μm-25 μm.
The embodiment of the invention provides a total layout of a film bulk acoustic resonator filter with a center frequency of 1805MHz as shown in figure 2. The overall layout of the filter in fig. 2 includes first through twelfth edition regions. The first plate area 401, the third plate area 403 and the fourth plate area 404 are grounded terminal plate areas, the second plate area 402 is an input terminal plate area, the fifth plate area 405 is an output terminal plate area, the first plate area 401 is located at the lower part of the layout of the filter, and the second plate area 402, the fifth plate area 405, the third plate area 403 and the fourth plate area 404 are symmetrically arranged at two sides of the layout of the filter respectively.
The sixth version region 406, the seventh version region 407, the eighth version region 408, and the ninth version region 409 are layout regions of the first film bulk acoustic resonator X1, the second film bulk acoustic resonator X2, the third film bulk acoustic resonator X3, and the fourth film bulk acoustic resonator X4, respectively; sixth edition area 406, seventh edition area 407, eighth edition area 408, and ninth edition area 409 are connected in series between second edition area 402 and fifth edition area 405, respectively. The first to fourth thin film bulk acoustic resonators X1 to X4 are connected in series between the input terminal and the output terminal in a substantially straight line.
The tenth version region 410, eleventh version region 411, and twelfth version region 412 are version regions of the fifth thin film bulk acoustic resonator X5, sixth thin film bulk acoustic resonator X6, and seventh thin film bulk acoustic resonator X7, respectively. Wherein the fifth film bulk acoustic resonator X5 and the seventh film bulk acoustic resonator X7 are located on a first side of a straight line, and the sixth film bulk acoustic resonator X6 is located on a second side of the straight line.
In some embodiments, the distance from the center of the first, second, third, and fourth thin film bulk acoustic resonators X1, X2, X3, and X4 to the first line where the input end is to the output end is less than the threshold, the resonators 31 and 33 are located on a first side of the first line, and the resonator 32 is located on a second side of the first line, the first side being opposite the second side.
The central connecting lines of the first film bulk acoustic resonator X1, the second film bulk acoustic resonator X2 and the fifth film bulk acoustic resonator X5 form a first V shape, the central connecting lines of the third film bulk acoustic resonator X3, the fourth film bulk acoustic resonator X4 and the seventh film bulk acoustic resonator X7 form a second V shape, and the central connecting lines of the second film bulk acoustic resonator X2, the third film bulk acoustic resonator and the sixth film bulk acoustic resonator X6 form a third V shape.
The angle of the first V-shaped and the second V-shaped is smaller than 90 degrees, and the opening directions of the first V-shaped and the second V-shaped face to the first side of the straight line; the angle of the third V-shaped is larger than 90 degrees, and the opening direction of the third V-shaped faces the second side of the straight line.
Specifically, referring to fig. 1 and 2, the first V-shape is constituted by a sixth edition region 406, a seventh edition region 407 and a tenth edition region 410, the second V-shape is constituted by an eighth edition region 408, a ninth edition region 409 and a twelfth edition region 412, and the seventh edition region 407, the ninth edition region 409 and the eleventh edition region 411.
For example: the distance between the center of the first to fourth thin film bulk acoustic resonators X1 to X4 and the dot-dash line where the input terminal 11 and the output terminal 12 are located (the dot-dash line between the second version region 402 and the fifth version region 405 as shown in fig. 2) is smaller than a threshold value, which may be the size of a half resonator or the size of a quarter resonator. Wherein the size of the resonator is the largest size of the resonator in a direction perpendicular to the above straight line in the sacrificial layer layout when the resonator is manufactured.
Specifically, the layout required to be used in the process of manufacturing the 1805MHz film bulk acoustic resonator filter mainly comprises a sacrificial layer layout, a lower electrode layout, an upper electrode layout, a difference frequency layer layout and a hole layer layout, as shown in figures 3-7.
Fig. 3 is a layout of a sacrificial layer in which first to seventh thin film bulk acoustic resonators X1 to X7 are respectively. The first sacrificial pattern region 501, the second sacrificial pattern region 502, the third sacrificial pattern region 503 and the fourth sacrificial pattern region 504 are sacrificial pattern regions of the first film bulk acoustic resonator X1, the second film bulk acoustic resonator X2, the third film bulk acoustic resonator X3 and the fourth film bulk acoustic resonator X4 respectively. The fifth sacrificial pattern region 505, the sixth sacrificial pattern region 506, and the seventh sacrificial pattern region 507 are sacrificial pattern regions of the fifth thin film bulk acoustic resonator X5, the sixth thin film bulk acoustic resonator X6, and the seventh thin film bulk acoustic resonator X7, respectively.
Wherein each resonator is provided with 5 sides respectively, and the resonators are connected with each other through one side respectively. And the protruding contact angle-shaped part of each resonator is a release channel, each resonator can be provided with a plurality of release channels, and each resonator is provided with 5 release channels in the application. The release gas enters the release channel through the release hole, then enters the sacrificial layer to corrode the sacrificial layer material into gas, and then is discharged through the release channel and the release hole.
Fig. 4 is a layout of the lower electrode layer, including a layout of the input terminal 11, the output terminal 12, and the ground terminal. Wherein the lower electrode layer comprises a first lower electrode plate area 601, a second lower electrode plate area 602, a third lower electrode plate area 603, a fourth lower electrode plate area 604, a fifth lower electrode plate area 605 and a sixth lower electrode plate area 606. Wherein the first lower electrode pad area 601, the third lower electrode pad area 603, and the fourth lower electrode pad area 604 are connected to a ground terminal. The second lower electrode pad 602 is connected to the input terminal 11, and the fifth lower electrode pad 605 is connected to the output terminal 12.
Wherein the first lower electrode plate region 601 corresponds to the ground terminal, the second lower electrode plate region 602 corresponds to the first thin film bulk acoustic resonator X1, the third lower electrode plate region 603 corresponds to the fifth thin film bulk acoustic resonator X5, the fourth lower electrode plate region 604 corresponds to the seventh thin film bulk acoustic resonator X7, the fifth lower electrode plate region 605 corresponds to the fourth thin film bulk acoustic resonator X4, and the sixth lower electrode plate region 604 corresponds to the second thin film bulk acoustic resonator X2, the third thin film bulk acoustic resonator X3, and the sixth thin film bulk acoustic resonator X6.
Fig. 5 is a layout of an upper electrode layer, including a first upper electrode pad 701, a second upper electrode pad 702, and a third upper electrode pad 703. Wherein the first upper electrode plate region 701 corresponds to the sixth film bulk acoustic resonator X6, the second upper electrode plate region 702 corresponds to the first film bulk acoustic resonator X1, the second film bulk acoustic resonator X2, and the fifth film bulk acoustic resonator X5, respectively, and the third upper electrode plate region 703 corresponds to the third film bulk acoustic resonator X3, the fourth film bulk acoustic resonator X4, and the seventh film bulk acoustic resonator X7, respectively.
Fig. 6 is a layout of a difference frequency layer, which includes a first difference frequency region 801 corresponding to a sixth thin film bulk acoustic resonator X6, a second difference frequency region 802 corresponding to a fifth thin film bulk acoustic resonator X5, and a third difference frequency region 803 corresponding to a seventh thin film bulk acoustic resonator X7.
Fig. 7 is a layout of an orifice layer including a plurality of relief holes 41 surrounding each resonator. One for each release hole 41. The release gas enters the release passage through the release holes 41, then enters the sacrificial layer region to corrode the sacrificial layer material into a gas, and then is discharged through the release passage and the release holes 41. In addition, in the probe test area on the hole layer layout, if a probe (e.g. a GSG probe) is required to test the chip, the piezoelectric layer needs to be etched away to expose the lower electrode GSG for testing.
In this example, the 1805MHz thin film bulk acoustic resonator filter prepared as described above was tested, and the test results are shown in fig. 8. Curve 1 is the S (2, 1) versus frequency curve (left vertical axis) for a thin film bulk acoustic resonator filter. Curve 2 is the return loss (right vertical axis) of S (1, 1) of the thin film bulk acoustic resonator filter, and curve 3 is the return loss (right vertical axis) of S (2, 2) of the thin film bulk acoustic resonator filter. As can be seen from FIG. 8, the 1dB bandwidth is about 40MHz, and the suppression levels are 53dBc and 51dBc at 1750MHz and 1860MHz, respectively.
The embodiment of the invention also provides a film bulk acoustic resonator filter assembly, which comprises any film bulk acoustic resonator filter. All technical effects of the thin film bulk acoustic resonator filter are not described herein.
The foregoing description of the preferred embodiments of the invention is not intended to be limiting, but rather is intended to cover all modifications, equivalents, and alternatives falling within the spirit and principles of the invention.
Claims (8)
1. The thin film bulk acoustic resonator filter is characterized by comprising an input terminal, an output terminal, a plurality of thin film bulk acoustic resonators connected in series and a plurality of thin film bulk acoustic resonators connected in parallel;
the plurality of thin film bulk acoustic resonators connected in series include a first thin film bulk acoustic resonator, a second thin film bulk acoustic resonator, a third thin film bulk acoustic resonator, and a fourth thin film bulk acoustic resonator connected in series between the input terminal and the output terminal;
the plurality of parallel thin film bulk acoustic resonators comprise a fifth thin film bulk acoustic resonator, a sixth thin film bulk acoustic resonator and a seventh thin film bulk acoustic resonator, and one ends of the fifth thin film bulk acoustic resonator, the sixth thin film bulk acoustic resonator and the seventh thin film bulk acoustic resonator are respectively connected to nodes between two adjacent thin film bulk acoustic resonators in the plurality of series thin film bulk acoustic resonators; the other ends of the fifth film bulk acoustic resonator, the sixth film bulk acoustic resonator and the seventh film bulk acoustic resonator are respectively connected with a grounding terminal;
the plurality of parallel thin film bulk acoustic resonators further comprises a first parallel arm resonator, a second parallel arm resonator and a third parallel arm resonator; the first parallel-arm resonator comprises the fifth film bulk acoustic resonator, the second parallel-arm resonator comprises the sixth film bulk acoustic resonator, and the third parallel-arm resonator comprises the seventh film bulk acoustic resonator;
the distance between the centers of the first film bulk acoustic resonator and the fourth film bulk acoustic resonator and the straight line where the input terminal and the output terminal are located is smaller than a threshold value, the fifth film bulk acoustic resonator and the seventh film bulk acoustic resonator are located on the first side of the straight line, and the sixth film bulk acoustic resonator is located on the second side of the straight line;
the distance from the center of the first film bulk acoustic resonator, the second film bulk acoustic resonator, the third film bulk acoustic resonator and the fourth film bulk acoustic resonator to a first straight line where the input end and the output end are positioned is smaller than a threshold value;
the center connecting lines of the first film bulk acoustic resonator, the second film bulk acoustic resonator and the fifth film bulk acoustic resonator form a first V shape, the center connecting lines of the third film bulk acoustic resonator, the fourth film bulk acoustic resonator and the seventh film bulk acoustic resonator form a second V shape, and the center connecting lines of the second film bulk acoustic resonator, the third film bulk acoustic resonator and the sixth film bulk acoustic resonator form a third V shape;
the angles of the first V-shaped and the second V-shaped are smaller than 90 degrees, and the opening directions of the first V-shaped and the second V-shaped face to the first side of the straight line; the angle of the third V-shaped is larger than 90 degrees, and the opening direction of the third V-shaped faces the second side of the straight line.
2. The thin film bulk acoustic resonator filter of claim 1, wherein the series resonant frequencies and the parallel resonant frequencies of the plurality of series thin film bulk acoustic resonators are the same; the series resonant frequency and the parallel resonant frequency of the plurality of parallel thin film bulk acoustic resonators are the same.
3. The thin film bulk acoustic resonator filter of claim 1 or 2, wherein a series resonance frequency of the plurality of series thin film bulk acoustic resonators is the same as a parallel resonance frequency of the plurality of parallel thin film bulk acoustic resonators.
4. The thin film bulk acoustic resonator filter of claim 1 wherein the first thin film bulk acoustic resonator has an area of 21300 μm 2 -21500μm 2 The second film bulk acoustic resonator has an area of 10700 μm 2 -10900μm 2 The third film bulk acoustic resonator has an area of 10100 μm 2 -10300μm 2 The area of the fourth film bulk acoustic resonator is 25200 mu m 2 -25400μm 2 The fifth film bulk acoustic resonator has an area of 29500 μm 2 -29700μm 2 The area of the sixth film bulk acoustic resonator is 37000 μm 2 -37200μm 2 The seventh film bulk acoustic resonator has an area of 23400 μm 2 -23600μm 2 。
5. The thin film bulk acoustic resonator filter of claim 1, wherein the thin film bulk acoustic resonator filter comprises a piezoelectric layer, the layout of the thin film bulk acoustic resonator filter mainly comprises a sacrificial layer, a lower electrode layer, an upper electrode layer, a difference frequency layer and a hole layer, the difference frequency layer corresponds to the plurality of thin film bulk acoustic resonators connected in parallel, and the plurality of thin film bulk acoustic resonators connected in series do not have the difference frequency layer; and a plurality of release holes are formed in the hole layer, each film bulk acoustic resonator is provided with a plurality of release channels, and each release channel at least corresponds to one release hole.
6. The thin film bulk acoustic resonator filter of claim 5 wherein the upper electrode layer and the lower electrode layer are each of a thickness ofThe thickness of the piezoelectric layer is +.>The thickness of the difference frequency layer isThe diameter of the release hole is 15-25 μm.
7. The film bulk acoustic resonator filter of claim 1, wherein the layout of the film bulk acoustic resonator filter comprises a first version region to a twelfth version region;
the first plate region, the third plate region and the fourth plate region are grounded terminal plate regions, the second plate region is an input terminal plate region, the fifth plate region is an output terminal plate region, the first plate region is positioned at the lower part of the layout of the filter, and the second plate region, the fifth plate region, the third plate region and the fourth plate region are symmetrically arranged at two sides of the layout of the filter respectively;
the sixth edition of drawing area, the seventh edition of drawing area, the eighth edition of drawing area and the ninth edition of drawing area are respectively edition of drawing areas of the first film bulk acoustic resonator, the second film bulk acoustic resonator, the third film bulk acoustic resonator and the fourth film bulk acoustic resonator; the sixth edition region, the seventh edition region, the eighth edition region and the ninth edition region are respectively connected in series between the second edition region and the fifth edition region;
the tenth edition of drawing area, the eleventh edition of drawing area and the twelfth edition of drawing area are edition of drawing areas of the fifth film bulk acoustic resonator, the sixth film bulk acoustic resonator and the seventh film bulk acoustic resonator respectively;
the eleventh layout area is positioned at the lower part of the seventh layout area, one end of the eleventh layout area is respectively connected with the seventh layout area and the eighth layout area, and the other end of the eleventh layout area is connected with the first layout area;
the tenth edition region is positioned at the upper part of the sixth edition region, one end of the tenth edition region is respectively connected with the sixth edition region and the seventh edition region, and the other end of the tenth edition region is connected with the third edition region;
the twelfth edition of region is positioned at the upper part of the eighth edition of region, one end of the twelfth edition of region is respectively connected with the eighth edition of region and the ninth edition of region, and the other end of the twelfth edition of region is connected with the fourth edition of region.
8. A thin film bulk acoustic resonator filter assembly comprising a thin film bulk acoustic resonator filter as claimed in any one of claims 1 to 7.
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