TSV-based stepped narrow-band piezoelectric thin-film bulk acoustic wave filter

Abstract

The present invention discloses a TSV-based stepped narrowband piezoelectric thin film bulk acoustic wave filter, comprising a silicon substrate, a silicon dioxide support layer provided on the silicon substrate, and a plurality of piezoelectric thin film bulk acoustic wave resonators distributed above the silicon dioxide support layer. The present invention can not only effectively reduce the volume of the filter, but also improve the performance of the filter.

Description

Technical Field

[0001] The invention belongs to the technical field of filters and relates to a stepped narrow-band piezoelectric thin film bulk acoustic wave filter based on TSV. Background Art

[0002] With the development of wireless communication technology, filters in RF chips have become one of the fastest growing and most indispensable modules. Thin Film Bulk Acoustic Resonator (FBAR) has excellent performance and good compatibility. Its devices can be applied to high-frequency bands and wireless communication RF front-ends that meet the needs of multi-standard communication technologies. It is the optimal solution for the expansion of high-frequency filters in the field of mobile communications.

[0003] FBAR is a device that realizes the frequency selection of the same electrical signal through the resonance of the sound signal. The working area is composed of the metal upper electrode-piezoelectric film-metal lower electrode. The structure, working mode and material selection of FBAR determine that it has the following characteristics: small size. Since the propagation speed of the bulk acoustic wave (about 331.5m / s) is only 1 / 100000 times the propagation speed of the electromagnetic wave (about 3.0*10^8m / s), the volume of the working device based on the bulk acoustic wave mode is also much smaller than that of the working device in the electromagnetic wave mode. The piezoelectric film material itself has a high Q value, which makes the resonator also have excellent characteristics. The processing technology is compatible and the yield is high. Common FBAR filter structures are usually ladder-type structures and bridge-type structures. This structure adopts the FBAR ladder-type structure.

[0004] TSV (Through Silicon Via) technology is an important part of three-dimensional integrated circuits. In 3D-IC, TSV acts as a "bridge" between layers to achieve information exchange and transmission between different layers. In planar integrated circuits, metal wires are used to connect chips, while in vertical interconnection, all different chips and systems can be stacked. It can significantly improve transmission efficiency, reduce power consumption and save costs, so that the design of integrated circuits is no longer restricted to the constraints of the two-dimensional plane and has more degrees of freedom. At the same time, it has good reliability in mechanical strength, thermal stress and heat dissipation. It is currently one of the best solutions to solve the size limit of two-dimensional integrated circuits. Summary of the invention

[0005] The object of the present invention is to provide a stepped narrow-band piezoelectric thin film bulk acoustic wave filter based on TSV, the filter structure of which can effectively reduce the volume of the filter and improve the performance of the filter.

[0006] The technical solution adopted by the present invention is a TSV-based stepped narrowband piezoelectric thin film bulk acoustic wave filter, which includes a silicon substrate, a silicon dioxide support layer is provided on the silicon substrate, and a plurality of piezoelectric thin film bulk acoustic wave resonators are distributed above the silicon dioxide support layer.

[0007] The present invention is also characterized in that:

[0008] The number of piezoelectric thin film bulk acoustic wave resonators is 12, and the 12 piezoelectric thin film bulk acoustic wave resonators are: resonator A, resonator B, resonator C, resonator D, resonator E, resonator F, resonator G, resonator H, resonator I, resonator J, resonator K, and resonator L; resonator A, resonator B, resonator C, resonator D, resonator E, and resonator F are connected in series in sequence, resonator G is connected in parallel with resonator A, resonator H is connected in parallel with resonator B, resonator I is connected in parallel with resonator C, resonator J is connected in parallel with resonator D, resonator K is connected in parallel with resonator E, and resonator L is connected in parallel with resonator F.

[0009] The structures of the 12 piezoelectric film bulk acoustic wave resonators are the same. The structure of a single resonator is: it includes a resonator piezoelectric film, four TSV cylinders are evenly distributed around the resonator piezoelectric film, the tops of the four TSV cylinders are connected together through a pentagonal top electrode, and the bottoms of the four TSV cylinders are connected together through a quadrilateral bottom electrode; a silicon dioxide support layer is provided between the bottom electrode and the piezoelectric film; a silicon dioxide isolation layer is provided between each TSV copper column and the piezoelectric film.

[0010] The top electrode and the bottom electrode are both made of copper.

[0011] The material of the piezoelectric film is AlN.

[0012] The beneficial effect of the present invention is that the structure of the present invention is a ladder filter design structure. The characteristics of such a series-parallel arrangement design can flexibly adjust the position between the resonators, reduce the area of ​​the filter and have a high degree of integration, thereby improving the independence of the filter. Compared with ordinary ladder filters, it can more reasonably utilize space in a limited space; greatly improve the bandwidth of the filter, and effectively improve the out-of-band suppression, with an insertion loss of less than 2dB and a return loss of less than 20dB; it has a compact design and a simple structure, and can be widely used in wireless communication systems. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of a stepped narrow-band piezoelectric thin film bulk acoustic wave filter based on TSV of the present invention;

[0014] Figure 2 is a plan view of a stepped narrow-band piezoelectric thin film bulk acoustic wave filter based on TSV of the present invention;

[0015] Figure 3 is a cross-sectional view of a stepped narrow-band piezoelectric thin film bulk acoustic wave filter based on TSV of the present invention;

[0016] Figure 4 is a side view of a stepped narrow-band piezoelectric thin film bulk acoustic resonator based on TSV of the present invention;

[0017] Figure 5 It is a plan view of a TSV cylinder in a stepped narrow-band piezoelectric thin film bulk acoustic wave filter based on TSV of the present invention;

[0018] Figure 6 This is a simulation curve of the S parameters of the resonator in the TSV-based stepped narrow-band piezoelectric thin film bulk acoustic wave filter.

[0019] In the figure, 1. input port, 2. output port, 3. GND, 4. TSV cylinder, 5. top electrode, 6. piezoelectric film, 7. silicon dioxide support layer, 8. bottom electrode, 9. resonator A, 10. resonator B, 11. resonator C, 12. resonator D, 13. resonator E, 14. resonator F, 15. resonator G, 16. resonator H, 17. resonator I, 18. resonator J, 19. resonator K, 20. resonator L, 21. silicon substrate, 22. air cavity, 23. silicon dioxide isolation layer. DETAILED DESCRIPTION

[0020] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The principle diagram of the stepped narrow-band piezoelectric thin film bulk acoustic wave filter based on TSV of the present invention is as follows: Figure 1 As shown, the filter is composed of 12 piezoelectric film bulk acoustic wave resonators connected in series and parallel (hereinafter, resonators refer to piezoelectric film bulk acoustic wave resonators); the present invention is a stepped narrow-band pass piezoelectric film bulk acoustic wave filter based on TSV, such as Figure 2 , 3 As shown, it includes a silicon substrate 21, a silicon dioxide support layer 7 is provided on the silicon substrate 21, and 12 piezoelectric thin film bulk acoustic wave resonators are distributed above the silicon dioxide support layer 7;

[0022] The 12 piezoelectric thin film bulk acoustic wave resonators are: resonator A9, resonator B10, resonator C11, resonator D12, resonator E13, resonator F14, resonator G15, resonator H16, resonator I17, resonator J18, resonator K19, resonator L20;

[0023] Resonator A9, resonator B10, resonator C11, resonator D12, resonator E13, and resonator F14 are connected in series in sequence, resonator G15 is connected in parallel with resonator A9, resonator H16 is connected in parallel with resonator B10, resonator I17 is connected in parallel with resonator C11, resonator J18 is connected in parallel with resonator D12, resonator K19 is connected in parallel with resonator E13, and resonator L20 is connected in parallel with resonator F14.

[0024] Resonator A9, resonator B10, resonator C11, resonator D12, resonator E13, resonator F14, resonator G15, resonator H16, resonator I17, resonator J18, resonator K19, and resonator L20 all have the same structure; Figures 3 to 5 As shown, it includes a resonator piezoelectric film 6, and four TSV cylinders 4 are evenly distributed around the resonator piezoelectric film 6. The tops of the four TSV cylinders 4 are connected together through a pentagonal top electrode 5, and the bottoms of the four TSV cylinders 4 are connected together through a quadrilateral bottom electrode 8; a silicon dioxide support layer 7 is provided between the bottom electrode 8 and the piezoelectric film 6; a silicon dioxide isolation layer 23 is provided between each TSV copper column 4 and the piezoelectric film 6.

[0025] The top electrode 5 on resonator A9 is connected to input port 1; the top electrode on resonator F14 is connected to output port 2; the top electrode 5 on resonator G15, resonator H16, resonator I17, resonator J18, resonator K19, and resonator L20 is connected to GND3;

[0026] Each TSV copper pillar 4 penetrates the piezoelectric film 6 to connect the top electrode 5 and the bottom electrode 8; the top electrode 5, the bottom electrode 8, GND 3 and the connecting wires used to connect the top electrodes 5 in the 12 resonators are all made of copper, with a thickness of 0.375um and a line width of 50um;

[0027] The material of the piezoelectric film 6 is AlN, with a thickness of 0.82 um;

[0028] The thickness of the air cavity 22 is 1.5um; the size of the silicon dioxide support layer 7 is 600×740um 2 , thickness is 0.15um.

[0029] In each resonator, the top electrode 5 is in the shape of a regular pentagonal prism, and the radius of the circumscribed circle of the top electrode in resonator A9, resonator B10, resonator D12, resonator E13, and resonator L20 is 32 um;

[0030] The radius of the circumscribed circle of the top electrode 5 in resonator C11 and resonator I17 is 39 um;

[0031] The radius of the circumscribed circle of the top electrode in resonator F14 and resonator IJ18 is 51 um, and the radius of the circumscribed circle of the top electrode 5 in resonator F14, resonator G15, and resonator J18 is 51 um;

[0032] The radius of the circumscribed circle of the top electrode 5 in resonator H16 and resonator K19 is 71 um;

[0033] The size of the piezoelectric film 6 and the air cavity 22 in resonator A9, resonator B10, resonator C11, resonator E13, and resonator L20 is 90*90um. 2 ;

[0034] The size of the piezoelectric film 6 and the air cavity 22 in the resonator F14 and the resonator I17 is 120*100um. 2 The piezoelectric film 6 and the air cavity 22 in the resonator G15, resonator H16, resonator J18, and resonator L20 are all sized 150*150um. 2 .

[0035] The insertion loss and return loss parameters of a single resonator in the TSV-based stepped narrow-band piezoelectric thin film bulk acoustic wave are as follows: Figure 6 As shown, its insertion loss S12 is less than 2dB and its return loss S11 is close to 20dB.

Claims

1. TSV-based stepped narrow-band piezoelectric thin film bulk acoustic wave filter, Features: It comprises a silicon substrate, a silicon dioxide support layer is arranged on the silicon substrate, and a plurality of piezoelectric thin film bulk acoustic wave resonators are distributed above the silicon dioxide support layer; The number of the piezoelectric thin film bulk acoustic wave resonators is 12, and the 12 piezoelectric thin film bulk acoustic wave resonators are respectively: resonator A, resonator B, resonator C, resonator D, resonator E, resonator F, resonator G, resonator H, resonator I, resonator J, resonator K, and resonator L; Resonator A, resonator B, resonator C, resonator D, resonator E, and resonator F are connected in series in sequence, resonator G is connected in parallel with resonator A, resonator H is connected in parallel with resonator B, resonator I is connected in parallel with resonator C, resonator J is connected in parallel with resonator D, resonator K is connected in parallel with resonator E, and resonator L is connected in parallel with resonator F; The structures of the 12 piezoelectric film bulk acoustic wave resonators are the same. The structure of a single resonator is: it includes a resonator piezoelectric film, four TSV cylinders are evenly distributed around the resonator piezoelectric film, the tops of the four TSV cylinders are connected together through a pentagonal top electrode, and the bottoms of the four TSV cylinders are connected together through a quadrilateral bottom electrode; an air cavity is provided between the bottom electrode and the piezoelectric film; a silicon dioxide isolation layer is provided between each TSV copper column and the piezoelectric film.

2. The TSV-based stepped narrow-band piezoelectric thin film bulk acoustic wave filter according to claim 1, Features: The top electrode and the bottom electrode are both made of copper.

3. The TSV-based stepped narrow-band piezoelectric thin film bulk acoustic wave filter according to claim 1, Features: The material of the piezoelectric film is AlN.

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