CN113852359A - Film bulk acoustic resonator structure and film bulk acoustic filter - Google Patents
Film bulk acoustic resonator structure and film bulk acoustic filter Download PDFInfo
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- 239000010410 layer Substances 0.000 claims abstract description 309
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- 239000011241 protective layer Substances 0.000 claims abstract description 14
- 239000010408 film Substances 0.000 claims description 61
- 238000000151 deposition Methods 0.000 claims description 29
- 238000005530 etching Methods 0.000 claims description 27
- 238000004519 manufacturing process Methods 0.000 claims description 20
- 230000008021 deposition Effects 0.000 claims description 18
- 239000010409 thin film Substances 0.000 claims description 16
- 239000000463 material Substances 0.000 claims description 15
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims description 12
- 238000012545 processing Methods 0.000 claims description 11
- 229910052581 Si3N4 Inorganic materials 0.000 claims description 6
- PMHQVHHXPFUNSP-UHFFFAOYSA-M copper(1+);methylsulfanylmethane;bromide Chemical compound Br[Cu].CSC PMHQVHHXPFUNSP-UHFFFAOYSA-M 0.000 claims description 6
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 6
- 235000012239 silicon dioxide Nutrition 0.000 claims description 6
- 239000000377 silicon dioxide Substances 0.000 claims description 6
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims description 6
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- 238000006731 degradation reaction Methods 0.000 description 2
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- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
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- H03H9/02007—Details of bulk acoustic wave devices
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- H—ELECTRICITY
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- 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
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- 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
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Abstract
The invention provides a film bulk acoustic resonator structure and a film bulk acoustic filter. The film bulk acoustic resonator comprises a substrate with a trapezoidal groove; a buffer layer is arranged above the substrate; a first cavity is formed between the groove and the buffer layer; a zigzag piezoelectric layer is arranged above the buffer layer; the lower surface of the n-shaped bulge of the piezoelectric layer is provided with a first electrode; a second cavity is formed between the first electrode and the buffer layer; the upper surface of the zigzag piezoelectric layer is provided with a second electrode; the protective layer covers the second electrode and the exposed surface of the deposited piezoelectric layer.
Description
Technical Field
The invention provides a film bulk acoustic resonator structure and a film bulk acoustic filter, and belongs to the technical field of filters.
Background
The resonator is the core component of the filter, and the quality of the performance of the resonator directly determines the quality of the performance of the filter. Among the existing resonators, a Film Bulk Acoustic Resonator (FBAR) has a very broad application prospect in the modern wireless communication technology due to its characteristics of small volume, low insertion loss, large out-of-band rejection, high quality factor, high working frequency, large power capacity, good antistatic impact capability and the like. At that time, in the conventional resonator, the piezoelectric layers between the adjacent film bulk acoustic resonators are communicated, and the piezoelectric layers in the area are directly contacted with the substrate, so that when the film bulk acoustic resonator works, part of acoustic waves in the piezoelectric oscillation stack can be transmitted into the substrate through the piezoelectric layers, thereby causing acoustic wave loss of the film bulk acoustic resonator, and further causing performance degradation of the film bulk acoustic resonator.
Disclosure of Invention
The invention provides a film bulk acoustic resonator structure and a film bulk acoustic filter, which are used for solving the problem that the performance of the film bulk acoustic resonator is reduced due to the acoustic loss of a resonator and the filter formed by the resonator:
a film bulk acoustic resonator comprises a substrate with a trapezoidal groove; a buffer layer is arranged above the substrate; a first cavity is formed between the groove and the buffer layer; a zigzag piezoelectric layer is arranged above the buffer layer; the lower surface of the n-shaped bulge of the piezoelectric layer is provided with a first electrode; a second cavity is formed between the first electrode and the buffer layer; the upper surface of the zigzag piezoelectric layer is provided with a second electrode; the protective layer covers the second electrode and the exposed surface of the deposited piezoelectric layer, wherein the film bulk acoustic resonator is obtained through the following processes:
step 4, paving a second sacrificial layer on the upper surface of the buffer layer; the first sacrificial layer and the second sacrificial layer are made of silicon dioxide or silicon nitride;
Furthermore, a plurality of through holes are arranged on the buffer layer, the through holes are communicated with the first cavity, and the diameter of each through hole and the first cavity have the following relationship:
0.33h≤d≤0.45h
wherein d represents the via diameter and h represents the vertical distance from the point of maximum depth of the first cavity to the horizontal plane of the buffer layer.
Further, the maximum depth of the first cavity is greater than the maximum depth of the second cavity.
Further, the first cavity maximum depth and the second cavity maximum depth satisfy the following relationship:
0.55（H1+H0）H1≤H2≤0.68（H1+H0）
wherein H1Represents a first cavity maximum depth; h2Represents a second cavity maximum depth; h0Denotes standard unit depth, H0=0.1mm。
Further, the first cavity is of an isosceles trapezoid structure; the second cavity is of a rectangular configuration and the isosceles trapezoid configuration has an angle of delivery ranging from 36 ° to 50 °, preferably 43 °.
Further, the step 5 of depositing the material for manufacturing the first electrode over the sacrificial layer and forming the first electrode layer over the sacrificial layer includes:
step 501, dividing a plurality of square areas on the upper surface of the second sacrificial layer to obtain a plurality of square areas;
step 502, depositing the electrode layers in each square area and the last rectangular area at the same time in a deposition mode by taking the central point of each square area and the central point of the last rectangular area as starting areas, and further connecting the electrode layers in the square areas and the last rectangular area to form a first electrode layer;
in step 501, dividing a plurality of square regions on the upper surface of the second sacrificial layer to obtain a plurality of square regions includes:
step 5011, setting the side length of the square area on the upper surface of the second sacrificial layer, wherein the side length of the square area is 1/2 of the length of the shortest side of the second sacrificial layer;
step 5012, dividing the upper surface of the second sacrificial layer into a plurality of square areas arranged in two rows according to the side length of the square areas, and dividing the last area according to a first area dividing principle when the last area cannot form the square area;
wherein the first region division principle is as follows: for the last area of the unsatisfied square structure, if the width dimension of the area is greater than 1/4, the area is a single rectangular area; if the region broadside dimension is less than 1/4 shortest side length, then the region is merged into the previous adjacent square region.
Further, the step 9 of forming a second electrode on the deposited piezoelectric layer includes:
step 901, obtaining an electrode area with the same range as the first electrode layer on the upper surface of the deposited voltage layer through graphic processing;
step 902, dividing the electrode area into a plurality of square areas;
step 903, depositing the electrode layers in each square area and the last rectangular area at the same time in a deposition mode by taking the center point of each square area and the center point of the last rectangular area as starting areas, and further connecting the electrode layers in the square areas and the last rectangular area to form a first electrode layer;
wherein the dividing of the electrode area into a plurality of square areas comprises:
step 9021, obtaining the side length of the electrode region, and setting the side length of the square region according to the side length of the electrode region, wherein the side length of the square is 1/2 of the length of the shortest side of the electrode region;
and 9022, dividing the upper surface of the deposition voltage layer into a plurality of square areas which are arranged in two rows, and dividing the last area according to a second area dividing principle when the last area cannot form the square area.
Wherein the second area division principle is as follows: for the last area of the unsatisfied square structure, if the width dimension of the area is greater than 3/4, the area is a single rectangular area; if the region broadside dimension is less than 3/4 shortest side length, then the region is merged into the previous adjacent square region.
A thin film bulk acoustic filter, the said thin film bulk acoustic filter includes the basal body with a plurality of isosceles trapezoid grooves; shallow grooves are formed among the isosceles trapezoid grooves to enable the isosceles trapezoid grooves to be communicated with one another; a buffer layer is arranged above the substrate; a first cavity is formed between the isosceles trapezoid grooves and the buffer layer; the number of the isosceles trapezoid grooves is the same as that of the film bulk acoustic resonators, and the isosceles trapezoid grooves correspond to the positions of the film bulk acoustic resonators; a zigzag piezoelectric layer is arranged above the buffer layer; the lower surface of the n-shaped bulge of the piezoelectric layer is provided with a first electrode; a second cavity is formed between the first electrode and the buffer layer; the upper surface of the zigzag piezoelectric layer is provided with a second electrode; the protective layer covers the second electrode and the exposed surface of the deposited piezoelectric layer; and through holes are formed in the buffer layer at the edge of the film bulk acoustic resonator distributed on the outermost side of the film bulk acoustic filter and are used for communicating the deposited piezoelectric layer with the first cavity.
Further, the manufacturing process of the film bulk acoustic wave filter comprises the following steps:
filling the isosceles trapezoid grooves and the shallow grooves to form a first sacrificial layer, wherein the upper surface of the first sacrificial layer and the upper surface of the substrate are positioned on the same horizontal plane;
step 4, paving a second sacrificial layer on the upper surface of the buffer layer; the first sacrificial layer and the second sacrificial layer are made of silicon dioxide or silicon nitride;
Further, the depth relationship between the isosceles trapezoid grooves and the shallow grooves meets the following conditions:
0.35W1<W2≤0.50W1
wherein, W2Represents the maximum depth of the shallow trench; w2Representing the maximum depth of the isosceles trapezoid groove.
The invention has the beneficial effects that:
according to the film bulk acoustic resonator structure and the manufacturing method thereof, the first cavity and the second cavity are designed in a matched mode, and the matching between the structures and the size designs of the first cavity and the second cavity can effectively reduce the acoustic loss of the film bulk acoustic resonator, so that the performance of the film bulk acoustic resonator is effectively prevented from being reduced, and the yield of the film bulk acoustic resonator in the manufacturing process is improved.
Drawings
FIG. 1 is a schematic diagram of a film bulk acoustic resonator according to the present invention;
FIG. 2 is a schematic diagram of a film bulk acoustic resonator according to the present invention;
FIG. 3 is a schematic diagram of a film bulk acoustic filter according to the present invention;
(1, substrate; 2, buffer layer; 3, second sacrificial layer; 4, first electrode; 5, deposited piezoelectric layer; 6, protective layer; 7, first sacrificial layer; 8, second electrode; 9, first cavity; 10, second cavity; 11, isosceles trapezoid groove; 12, shallow trench).
Detailed Description
The preferred embodiments of the present invention will be described in conjunction with the accompanying drawings, and it will be understood that they are described herein for the purpose of illustration and explanation and not limitation.
An embodiment of the present invention provides a film bulk acoustic resonator, as shown in fig. 1 and fig. 2, where the film bulk acoustic resonator includes a substrate with a trapezoidal groove; a buffer layer is arranged above the substrate; a first cavity is formed between the groove and the buffer layer; a zigzag piezoelectric layer is arranged above the buffer layer; the lower surface of the n-shaped bulge of the piezoelectric layer is provided with a first electrode; a second cavity is formed between the first electrode and the buffer layer; the upper surface of the zigzag piezoelectric layer is provided with a second electrode; the protective layer covers the second electrode and the exposed surface of the deposited piezoelectric layer.
The buffer layer is provided with a plurality of through holes, the through holes are communicated with the first cavity, and the diameter of each through hole and the first cavity have the following relationship:
0.33h≤d≤0.45h
wherein d represents the via diameter and h represents the vertical distance from the point of maximum depth of the first cavity to the horizontal plane of the buffer layer.
The maximum depth of the first cavity is greater than the maximum depth of the second cavity. The first cavity maximum depth and the second cavity maximum depth satisfy the following relationship:
0.55（H1+H0）H1≤H2≤0.68（H1+H0）
wherein H1Represents a first cavity maximum depth; h2Represents a second cavity maximum depth; h0Denotes standard unit depth, H0=0.1mm。
The first cavity is of an isosceles trapezoid structure; the second cavity is of a rectangular configuration and the isosceles trapezoid configuration has an angle of delivery ranging from 36 ° to 50 °, preferably 43 °.
The working principle and the effect of the technical scheme are as follows: the film bulk acoustic resonator structure that this embodiment provided can be through first cavity and second cavity cooperation design to and, the cooperation between the structure of first cavity and second cavity and the size design can effectively reduce film bulk acoustic resonator's sound wave loss, thereby effectively prevents film bulk acoustic resonator's performance degradation, improves the yields in the film bulk acoustic resonator manufacturing process. On the other hand, through the arrangement of the shape structures of the first cavity and the second cavity, the manufacturing complexity of the thin film resonator under the condition of a plurality of cavity areas can be effectively reduced, and the manufacturing efficiency of the thin film resonator is improved. Simultaneously, through the setting of the depth proportional relation condition between the first cavity and the second cavity and the range setting of the trapezoid base angle of the first cavity, the first cavity and the second cavity can reduce the acoustic wave loss to a great extent under the condition that the film bulk acoustic wave resonator is required to be filled and supplemented by other supports or consolidation substances due to excessive loss of a base body without ensuring, the resonator processing link and the resonator structure complexity are reduced, and the processing efficiency is improved.
When a plurality of thin film resonators form a filter, the acoustic loss of the substrate to the thin film bulk acoustic resonator can be further reduced through the communication of the first cavities corresponding to the plurality of thin film resonators, and the performance quality and the yield of the whole filter can still be improved to a great extent under the condition of the multistage resonators. Simultaneously, can enough guarantee to have sufficient connectivity and then reduce the acoustic loss between deposit piezoelectric layer and the first cavity through the setting of above-mentioned through-hole size, can guarantee again that piezoelectric layer and buffering increase between area of contact's sufficiency and buffer layer's relative integrality, prevent that the through-hole from seting up too big problem emergence that leads to buffer layer performance to reduce.
In one embodiment of the present invention, the film bulk acoustic resonator is obtained by the following process:
step 4, paving a second sacrificial layer on the upper surface of the buffer layer; the first sacrificial layer and the second sacrificial layer are made of silicon dioxide or silicon nitride;
Wherein the step 5 of depositing a material for making a first electrode over the sacrificial layer and forming a first electrode layer over the sacrificial layer comprises:
step 501, dividing a plurality of square areas on the upper surface of the second sacrificial layer to obtain a plurality of square areas;
step 502, depositing the electrode layers in each square area and the last rectangular area at the same time in a deposition mode by taking the central point of each square area and the central point of the last rectangular area as starting areas, and further connecting the electrode layers in the square areas and the last rectangular area to form a first electrode layer;
step 501, dividing a plurality of square regions on the upper surface of the second sacrificial layer to obtain a plurality of square regions, including:
step 5011, setting the side length of the square area on the upper surface of the second sacrificial layer, wherein the side length of the square area is 1/2 of the length of the shortest side of the second sacrificial layer;
step 5012, dividing the upper surface of the second sacrificial layer into a plurality of square areas arranged in two rows according to the side length of the square areas, and dividing the last area according to a first area dividing principle when the last area cannot form the square area;
wherein the first region division principle is as follows: for the last area of the unsatisfied square structure, if the width dimension of the area is greater than 1/4, the area is a single rectangular area; if the region broadside dimension is less than 1/4 shortest side length, then the region is merged into the previous adjacent square region.
step 901, obtaining an electrode area with the same range as the first electrode layer on the upper surface of the deposited voltage layer through graphic processing;
step 902, dividing the electrode area into a plurality of square areas;
step 903, depositing the electrode layers in each square area and the last rectangular area at the same time in a deposition mode by taking the center point of each square area and the center point of the last rectangular area as starting areas, and further connecting the electrode layers in the square areas and the last rectangular area to form a first electrode layer;
wherein the dividing of the electrode area into a plurality of square areas comprises:
step 9021, obtaining the side length of the electrode region, and setting the side length of the square region according to the side length of the electrode region, wherein the side length of the square is 1/2 of the length of the shortest side of the electrode region;
and 9022, dividing the upper surface of the deposition voltage layer into a plurality of square areas which are arranged in two rows, and dividing the last area according to a second area dividing principle when the last area cannot form the square area.
Wherein the second area division principle is as follows: for the last area of the unsatisfied square structure, if the width dimension of the area is greater than 3/4, the area is a single rectangular area; if the region broadside dimension is less than 3/4 shortest side length, then the region is merged into the previous adjacent square region.
The effect of the above technical scheme is as follows: because the uneven problem of easy production center and edge thickness among the electrode deposition process, need to carry out the adjustment of deposition thickness repeatedly and just can not guarantee the uniformity of electrode layer thickness, this not only leads to film resonator to produce the performance reduction because of electrode thickness is inconsistent easily, still can reduce electrode layer manufacturing efficiency in the very big degree, consequently, carry out the mode of deposit through above-mentioned subregion, reduce the inconsistent problem of electrode thickness that large tracts of land deposit caused through the mode that reduces unit deposition area, and simultaneously, deposit formation electrode layer through the regional while of a plurality of squares, can effectively improve electrode layer forming speed. Furthermore, the manufacturing efficiency of the electrode layer can be improved, and the consistency of the thickness of each region of the electrode layer can be ensured under the condition that the area of the electrode layer is large. On the other hand, because the restriction of the mode of depositing the electrode layer leads to if single regional undersize, can influence the effect of depositing the electrode layer on the contrary not good, consequently, set up the length of side in square region through above-mentioned mode, can guarantee that square region not only can satisfy the efficiency demand that the electrode layer formed, can not influence electrode layer deposition effect and formation quality for square region division undersize too much simultaneously, and then effectively improve the rationality that square region formed. Because film resonator's actual size can not guarantee that the square region can be covered with according to complete regional division, consequently, can guarantee the rationality of last regional division through above-mentioned rule, can enough guarantee that the division of last region can not cause the not good problem of electrode layer manufacturing quality to take place because of regional undersize, can guarantee again that last region can not lead to the inconsistent problem of electrode layer thickness to take place because too big.
The embodiment of the invention provides a film bulk acoustic wave filter, as shown in fig. 3, the film bulk acoustic wave filter includes a substrate with a plurality of isosceles trapezoid grooves; shallow grooves are formed among the isosceles trapezoid grooves to enable the isosceles trapezoid grooves to be communicated with one another; a buffer layer is arranged above the substrate; a first cavity is formed between the isosceles trapezoid grooves and the buffer layer; the number of the isosceles trapezoid grooves is the same as that of the film bulk acoustic resonators, and the isosceles trapezoid grooves correspond to the positions of the film bulk acoustic resonators; a zigzag piezoelectric layer is arranged above the buffer layer; the lower surface of the n-shaped bulge of the piezoelectric layer is provided with a first electrode; a second cavity is formed between the first electrode and the buffer layer; the upper surface of the zigzag piezoelectric layer is provided with a second electrode; the protective layer covers the second electrode and the exposed surface of the deposited piezoelectric layer; and through holes are formed in the buffer layer at the edge of the film bulk acoustic resonator distributed on the outermost side of the film bulk acoustic filter and are used for communicating the deposited piezoelectric layer with the first cavity.
Wherein, the manufacturing process of the film bulk acoustic wave filter comprises the following steps:
filling the isosceles trapezoid grooves and the shallow grooves to form a first sacrificial layer, wherein the upper surface of the first sacrificial layer and the upper surface of the substrate are positioned on the same horizontal plane;
step 4, paving a second sacrificial layer on the upper surface of the buffer layer; the first sacrificial layer and the second sacrificial layer are made of silicon dioxide or silicon nitride;
Wherein, the depth relation between the isosceles trapezoid groove and the shallow groove meets the following conditions:
0.35W1<W2≤0.50W1
wherein, W2Represents the maximum depth of the shallow trench; w2Representing the maximum depth of the isosceles trapezoid groove.
The effect of the above technical scheme is as follows: through the shape structure of the first cavity and the second cavity and the arrangement of the depth proportional relation between the isosceles trapezoid grooves and the shallow grooves, the manufacturing complexity of the filter can be effectively reduced and the manufacturing efficiency of the thin film filter can be improved for the filter of the multistage thin film resonator. Meanwhile, under the condition that the plurality of thin film resonators form the filter, the acoustic loss of the substrate to the thin film bulk acoustic resonator can be further reduced through the communication of the first cavities corresponding to the plurality of thin film resonators, and under the condition of the multistage resonators, the performance quality and the yield of the whole filter can be still improved to a great extent.
It will be apparent to those skilled in the art that various changes and modifications may be made in the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. A film bulk acoustic resonator is characterized by comprising a substrate with a trapezoidal groove; a buffer layer is arranged above the substrate; a first cavity is formed between the groove and the buffer layer; a zigzag piezoelectric layer is arranged above the buffer layer; the lower surface of the n-shaped bulge of the piezoelectric layer is provided with a first electrode; a second cavity is formed between the first electrode and the buffer layer; the upper surface of the zigzag piezoelectric layer is provided with a second electrode; the protective layer covers the second electrode and the exposed surface of the deposited piezoelectric layer, wherein the film bulk acoustic resonator is obtained through the following processes:
step 1, providing a substrate, and etching a first groove on the substrate;
step 2, filling the first groove to form a first sacrificial layer, wherein the upper surface of the first sacrificial layer and the upper surface of the substrate are positioned on the same horizontal plane;
step 3, arranging buffer layers on the upper surfaces of the substrate and the first sacrificial layer; wherein the buffer layer is made of aluminum nitride or aluminum oxide;
step 4, paving a second sacrificial layer on the upper surface of the buffer layer; the first sacrificial layer and the second sacrificial layer are made of silicon dioxide or silicon nitride;
step 5, arranging a material for manufacturing a first electrode above the sacrificial layer, and forming a first electrode layer above the sacrificial layer;
step 6, carrying out graphical processing on the upper surface of the first electrode layer, and etching the first electrode layer and the second sacrificial layer together according to the graphical processed graph to obtain a first electrode and an etched second sacrificial layer positioned below the first electrode;
step 7, arranging a sacrificial layer extension part connected with the first sacrificial layer on the buffer layer exposed after etching;
step 8, forming a deposited piezoelectric layer above the first electrode, the buffer layer exposed after etching and the sacrificial material filled in the through hole arranged on the buffer layer in a deposition mode;
step 9, forming a second electrode on the deposited piezoelectric layer, wherein the thicknesses of the second electrode, the deposited piezoelectric layer and the first electrode are the same;
step 10, removing the first sacrificial layer, the sacrificial layer extending part and the second sacrificial layer to form a first cavity and a second cavity; and laying the protective layer on the second electrode and the deposited voltage layer not covered by the second electrode.
2. The film bulk acoustic resonator according to claim 1, wherein the buffer layer is provided with a plurality of through holes, the through holes communicate with the first cavity, and the diameters of the through holes and the first cavity have the following relationship:
0.33h≤d≤0.45h
wherein d represents the diameter of the through hole, and h represents the vertical distance from the maximum depth point of the first cavity to the horizontal plane of the buffer layer.
3. The film bulk acoustic resonator of claim 1, wherein a maximum depth of the first cavity is greater than a maximum depth of the second cavity.
4. The film bulk acoustic resonator of claim 3, wherein the first cavity maximum depth and the second cavity maximum depth satisfy the following relationship:
0.55（H1+H0）H1≤H2≤0.68（H1+H0）
wherein H1Represents a first cavity maximum depth; h2Represents a second cavity maximum depth; h0Denotes standard unit depth, H0=0.1mm。
5. The film bulk acoustic resonator of claim 1, wherein the first cavity has an isosceles trapezoid structure; the second cavity is in a rectangular structure, and the delivery angle of the isosceles trapezoid structure ranges from 36 degrees to 50 degrees.
6. The thin film bulk acoustic resonator of claim 1, wherein the step 5 of depositing a material for fabricating the first electrode over the sacrificial layer and forming a first electrode layer over the sacrificial layer comprises:
step 501, dividing a plurality of square areas on the upper surface of the second sacrificial layer to obtain a plurality of square areas;
step 502, depositing the electrode layers in each square area and the last rectangular area at the same time in a deposition mode by taking the central point of each square area and the central point of the last rectangular area as starting areas, and further connecting the electrode layers in the square areas and the last rectangular area to form a first electrode layer;
in step 501, dividing a plurality of square regions on the upper surface of the second sacrificial layer to obtain a plurality of square regions includes:
step 5011, setting the side length of the square area on the upper surface of the second sacrificial layer, wherein the side length of the square area is 1/2 of the length of the shortest side of the second sacrificial layer;
step 5012, dividing the upper surface of the second sacrificial layer into a plurality of square areas arranged in two rows according to the side length of the square areas, and dividing the last area according to a first area dividing principle when the last area cannot form the square area;
wherein the first region division principle is as follows: for the last area of the unsatisfied square structure, if the width dimension of the area is greater than 1/4, the area is a single rectangular area; if the region broadside dimension is less than 1/4 shortest side length, then the region is merged into the previous adjacent square region.
7. The thin film bulk acoustic resonator of claim 1, wherein the step 9 of forming a second electrode on the deposited piezoelectric layer comprises:
step 901, obtaining an electrode area with the same range as the first electrode layer on the upper surface of the deposited voltage layer through graphic processing;
step 902, dividing the electrode area into a plurality of square areas;
step 903, depositing the electrode layers in each square area and the last rectangular area at the same time in a deposition mode by taking the center point of each square area and the center point of the last rectangular area as starting areas, and further connecting the electrode layers in the square areas and the last rectangular area to form a first electrode layer;
wherein the dividing of the electrode area into a plurality of square areas comprises:
step 9021, obtaining the side length of the electrode region, and setting the side length of the square region according to the side length of the electrode region, wherein the side length of the square is 1/2 of the length of the shortest side of the electrode region;
9022, dividing the upper surface of the deposition voltage layer into a plurality of square areas which are arranged in two rows, and dividing the last area according to a second area dividing principle when the last area cannot form the square area;
wherein the second area division principle is as follows: for the last area of the unsatisfied square structure, if the width dimension of the area is greater than 3/4, the area is a single rectangular area; if the region broadside dimension is less than 3/4 shortest side length, then the region is merged into the previous adjacent square region.
8. A film bulk acoustic wave filter is characterized by comprising a substrate with a plurality of isosceles trapezoid grooves; shallow grooves are formed among the isosceles trapezoid grooves to enable the isosceles trapezoid grooves to be communicated with one another; a buffer layer is arranged above the substrate; a first cavity is formed between the isosceles trapezoid grooves and the buffer layer; the number of the isosceles trapezoid grooves is the same as that of the film bulk acoustic resonators, and the isosceles trapezoid grooves correspond to the positions of the film bulk acoustic resonators; a zigzag piezoelectric layer is arranged above the buffer layer; the lower surface of the n-shaped bulge of the piezoelectric layer is provided with a first electrode; a second cavity is formed between the first electrode and the buffer layer; the upper surface of the zigzag piezoelectric layer is provided with a second electrode; the protective layer covers the second electrode and the exposed surface of the deposited piezoelectric layer; and through holes are formed in the buffer layer at the edge of the film bulk acoustic resonator distributed on the outermost side of the film bulk acoustic filter and are used for communicating the deposited piezoelectric layer with the first cavity.
9. The thin film bulk acoustic wave filter of claim 8, wherein the manufacturing process of the thin film bulk acoustic wave filter comprises:
step 1, providing a substrate, etching a plurality of isosceles trapezoid grooves on the substrate, and etching shallow grooves among the plurality of isosceles trapezoid grooves, wherein the depth of each shallow groove is smaller than that of each isosceles trapezoid groove;
filling the isosceles trapezoid grooves and the shallow grooves to form a first sacrificial layer, wherein the upper surface of the first sacrificial layer and the upper surface of the substrate are positioned on the same horizontal plane;
step 3, arranging buffer layers on the upper surfaces of the substrate and the first sacrificial layer; wherein the buffer layer is made of aluminum nitride or aluminum oxide;
step 4, paving a second sacrificial layer on the upper surface of the buffer layer; the first sacrificial layer and the second sacrificial layer are made of silicon dioxide or silicon nitride;
step 5, arranging a material for manufacturing a first electrode above the sacrificial layer, and forming a first electrode layer above the sacrificial layer;
step 6, carrying out patterning processing on the upper surface of the first electrode layer, and etching the first electrode layer and the second sacrificial layer together according to the patterned graphics to obtain a plurality of first electrodes and etched second sacrificial layers positioned below the first electrodes; the position corresponding to the first electrode is the setting position of a film bulk acoustic resonator;
step 7, arranging a sacrificial layer extension part connected with the first sacrificial layer at the outer side edge of the film bulk acoustic resonator distributed close to the outermost side on the buffer layer exposed after etching;
step 8, forming a deposited piezoelectric layer above the first electrode, the buffer layer exposed after etching and the sacrificial material filled in the through hole in a deposition mode;
step 9, forming a second electrode on the deposited piezoelectric layer, wherein the thicknesses of the second electrode, the deposited piezoelectric layer and the first electrode are the same;
step 10, removing the first sacrificial layer, the sacrificial layer extending part and the second sacrificial layer to form a first cavity and a second cavity; and laying a protective layer over the second electrode and the deposited voltage layer not covered by the second electrode.
10. The film bulk acoustic wave filter according to claim 8 or 9, wherein the depth relationship between the isosceles trapezoid grooves and the shallow grooves satisfies the following condition:
0.35W1<W2≤0.50W1
wherein, W2Represents the maximum depth of the shallow trench; w2Representing the maximum depth of the isosceles trapezoid groove.
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