Bulk acoustic wave filter integrated with IPD and wireless communication equipment

Abstract

The utility model provides an IPD-integrated bulk acoustic wave filter and wireless communication equipment, and relates to the technical field of semiconductors. The bulk acoustic wave filter integrated with the IPD comprises a substrate, an acoustic wave reflection structure arranged on the substrate, a film bulk acoustic wave resonator, a parallel plate capacitor and a planar inductor, the film bulk acoustic wave resonator is located above the acoustic wave reflection structure, and the planar inductor is located between the film bulk acoustic wave resonator and the parallel plate capacitor. And the thin film bulk acoustic resonator and the parallel plate capacitor are electrically connected with each other. According to the bulk acoustic wave filter integrated with the IPD, the IPD technology is integrated into the BAW technology, and the integration level and the area utilization rate of the filter are greatly improved. A resonance circuit of the IPD is designed to generate an extremely wide passband, then the bulk acoustic wave resonators are designed, and the frequency of the bulk acoustic wave resonators falls on the two sides of the passband to improve roll-off of the filter, so that the wide passband can be generated, and the good out-of-band rejection effect can be achieved. In addition, by adopting the planar inductor, the technological process of the inductor structure is greatly simplified.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular, to a bulk acoustic wave filter integrating IPD and a wireless communication device. Background Art

[0002] At present, 5G communication technology has gradually developed and been commercialized. With the explosive growth of mobile data traffic, the demand for the development of future 6G communication technology is becoming increasingly strong, and high frequency, high power, and large bandwidth are the core directions for the development of future filters.

[0003] In recent years, thin film bulk acoustic resonators (FBARs) have become the best choice for realizing 5G radio frequency filters due to their unique properties such as high frequency and miniaturization. However, traditional thin film bulk acoustic wave filters are limited by the electromechanical coupling coefficient of piezoelectric ceramics and have a relatively narrow absolute bandwidth. However, the roll-off and suppression of thin film bulk acoustic wave filters are significantly better than those of integrated passive devices (IPDs). The manufacturing process complexity of IPDs is lower than that of BAW (Bulk Acoustic Wave). The bandwidth of filters made with IPDs can be much wider than that of BAW. Therefore, in the prior art, IPDs and BAWs are separately packaged and then welded together to achieve both a wide passband and good out-of-band suppression. However, the solutions of the prior art are complex to operate, have low integration, and the resulting device structures are also relatively complex. Summary of the Utility Model

[0004] The purpose of this application is to provide, in view of the above deficiencies in the prior art, a bulk acoustic wave filter integrating IPD and a wireless communication device, which have a relatively wide bandwidth and good out-of-band suppression, and are simple in process and high in integration.

[0005] To achieve the above purpose, the technical solutions adopted in the embodiments of this application are as follows:

[0006] One aspect of the embodiments of this application provides a bulk acoustic wave filter integrating IPD, including: a substrate, an acoustic wave reflection structure disposed in the substrate, and a thin film bulk acoustic resonator, a parallel plate capacitor, and a planar inductor attached to the surface of the substrate. The thin film bulk acoustic resonator is located above the acoustic wave reflection structure, and the planar inductor is electrically connected to the thin film bulk acoustic resonator and the parallel plate capacitor respectively.

[0007] Optionally, the thin film bulk acoustic resonator includes a first bottom electrode, a first piezoelectric layer stacked on the side of the first bottom electrode away from the substrate, and a first top electrode. The parallel plate capacitor includes a second bottom electrode, a second piezoelectric layer stacked on the side of the second bottom electrode away from the substrate, and a second top electrode.

[0008] Optionally, one end of the planar inductor is connected to the first bottom electrode or the first top electrode, and the other end of the planar inductor is connected to the second bottom electrode or the second top electrode.

[0009] Optionally, the planar inductor is a folded inductor.

[0010] Optionally, the planar inductor includes a first straight portion and a second straight portion perpendicular to the first straight portion. Two ends of the second straight portion are respectively connected to two first straight portions, and two ends of the first straight portion are respectively connected to two second straight portions. Alternatively, two ends of the first straight portion are respectively connected to the thin film bulk acoustic resonator and the second straight portion. Alternatively, two ends of the first straight portion are respectively connected to the parallel plate capacitor and the second straight portion.

[0011] Optionally, the length direction of the first straight portion is parallel to the sequential arrangement direction of the thin film bulk acoustic resonator and the parallel plate capacitor.

[0012] Optionally, the number of the first straight portions and the number of the second straight portions are both multiple, and the lengths of the multiple second straight portions are not completely equal.

[0013] Optionally, the lengths of the multiple first straight portions are equal.

[0014] Optionally, the acoustic reflection structure is a cavity provided on the upper surface of the substrate.

[0015] On the other hand, an embodiment of the present application provides a wireless communication device, including the bulk acoustic wave filter integrated with IPD as described in any one of the above.

[0016] The beneficial effects of the present application include:

[0017] The present application provides a bulk acoustic wave filter integrating IPD, comprising: a substrate, an acoustic wave reflection structure disposed on the substrate, a thin film bulk acoustic resonator, a parallel plate capacitor, and a planar inductor. The thin film bulk acoustic resonator is located above the acoustic wave reflection structure, and the planar inductor is located between the thin film bulk acoustic resonator and the parallel plate capacitor and is electrically connected to the thin film bulk acoustic resonator and the parallel plate capacitor respectively. This bulk acoustic wave filter integrating IPD integrates the IPD process into the BAW process, greatly improving the integration degree and area utilization rate of the filter. By designing the resonant circuit of the IPD to generate an extremely wide passband, and then designing the bulk acoustic resonator and making its frequency fall on both sides of the passband to improve the roll-off of the filter, the effect of generating a wide passband and having good out-of-band rejection can be achieved. In addition, the inductor used in the traditional IPD is a wound inductor. An output port is led out from the center of the inductor, and a bridge structure is used to cross the outer winding of the inductor to realize the output of the signal. This method has a complex process and still cannot completely eliminate the influence of the electromagnetic environment. However, the planar inductor used in the embodiments of the present application is a pure planar circuit, with a simple process, and can be directly integrated into the process route of the bulk acoustic wave filter, greatly simplifying the process flow of the inductor structure. The transmission characteristics of the filter can also be predicted through full-wave electromagnetic simulation in the later stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings required to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other relevant drawings can be obtained based on these drawings without creative efforts.

[0019] Figure 1 It is a cross-sectional view of the bulk acoustic wave filter integrating IPD provided by the embodiments of the present application;

[0020] Figure 2 It is a simulation result diagram of the bulk acoustic wave filter integrating IPD provided by the embodiments of the present application;

[0021] Figure 3 It is a top view of the bulk acoustic wave filter integrating IPD provided by the embodiments of the present application.

[0022] Reference numerals: 100 - bulk acoustic wave filter integrating IPD; 110 - substrate; 120 - acoustic wave reflection structure;

[0023] 130 - Thin film bulk acoustic resonator; 131 - First bottom electrode; 132 - First piezoelectric layer; 133 - First top electrode; 140 - Parallel plate capacitor; 141 - Second bottom electrode; 142 - Second piezoelectric layer; 143 - Second top electrode; 150 - Planar inductor; 151 - First straight portion; 152 - Second straight portion. Detailed implementation mode

[0024] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of this application. Obviously, the described embodiments are some, but not all, of the embodiments of this application. Usually, the components of the embodiments of this application described and illustrated in the accompanying drawings here can be arranged and designed in various different configurations.

[0025] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of this application that is claimed, but merely represents selected embodiments of this application. It should be noted that, without conflict, the various features in the embodiments of this application can be combined with each other, and the combined embodiments are still within the scope of protection of this application.

[0026] It should be noted that similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0027] In the description of this application, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the products of this application are customarily placed when in use. It is only for the convenience of describing this application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application. In addition, the terms "first", "second", "third", etc. are only used for descriptive distinction and cannot be understood as indicating or implying relative importance.

[0028] In the description of this application, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0029] Please refer to Figure 1 In one aspect of the embodiment of the present application, a bulk acoustic wave filter 100 integrated with IPD is provided, including: a substrate 110, an acoustic wave reflection structure 120 disposed in the substrate 110, and a thin film bulk acoustic wave resonator 130, a parallel plate capacitor 140, and a planar inductor 150 attached to the surface of the substrate 110. The thin film bulk acoustic wave resonator 130 is located above the acoustic wave reflection structure 120, and the planar inductor 150 is electrically connected to the thin film bulk acoustic wave resonator 130 and the parallel plate capacitor 140 respectively.

[0030] It should be noted that the substrate 110 can be a single-layer structure or a two-layer or multi-layer composite structure. Exemplarily, the substrate 110 is a single-layer silicon wafer substrate. The thin film bulk acoustic wave resonator 130, the parallel plate capacitor 140, and the planar inductor 150 are all attached to the surface of the substrate 110. An acoustic wave reflection structure 120 is further disposed in the substrate 110. The acoustic wave reflection structure 120 is located below the thin film bulk acoustic wave resonator 130 for reflecting acoustic waves, thereby forming acoustic wave resonance in the thin film bulk acoustic wave resonator 130. The planar inductor 150 has two signal output terminals, and the two signal output terminals are electrically connected to the thin film bulk acoustic wave resonator 130 and the parallel plate capacitor 140 respectively. Exemplarily, the planar inductor 150 is located between the thin film bulk acoustic wave resonator 130 and the parallel plate capacitor 140 to facilitate the connection among the three.

[0031] The above-mentioned bulk acoustic wave filter 100 integrated with IPD integrates the IPD process into the BAW process, generates an extremely wide passband by designing the resonant circuit of IPD, and then designs a bulk acoustic wave resonator and makes its frequency fall on both sides of the passband to improve the roll-off of the filter, thereby achieving the effect of both generating a wide passband and having good out-of-band rejection.

[0032] In addition, the inductor used in traditional IPD is a loop-shaped inductor, and an output port is led out from the center of the inductor, and a bridge structure is used to cross the outer winding of the inductor to achieve signal output. This method has a complex process and still cannot completely eliminate the influence of the electromagnetic environment. However, the planar inductor 150 used in the embodiment of the present application is a pure planar circuit, with a simple process, and can be directly integrated into the process route of the bulk acoustic wave filter, greatly simplifying the process flow of the inductor structure, and the transmission characteristics of the filter can also be predicted through full-wave electromagnetic simulation in the later stage.

[0033] Please refer to in combination Figure 2 Ordinary IPD can achieve the transmission characteristics shown by the dotted line, with a relatively wide bandwidth but poor out-of-band rejection. As shown by the solid line in the figure, after adding a thin film bulk acoustic wave filter to the circuit, the out-of-band rejection and roll-off of the filter can be significantly improved without affecting the bandwidth of the filter.

[0034] Optionally, please refer to Figure 1, the thin film bulk acoustic wave resonator 130 includes a first bottom electrode 131, a first piezoelectric layer 132 stacked on one side of the first bottom electrode 131 away from the substrate 110, and a first top electrode 133. The parallel plate capacitor 140 includes a second bottom electrode 141, a second piezoelectric layer 142 stacked on one side of the second bottom electrode 141 away from the substrate 110, and a second top electrode 143.

[0035] The lower surface of the first bottom electrode 131 of the thin film bulk acoustic wave resonator 130 is attached to the substrate 110, and the upper surface is attached to the lower surface of the first piezoelectric layer 132. The upper surface of the first piezoelectric layer 132 is then attached to the lower surface of the first top electrode 133. The lower surface of the second bottom electrode 141 of the parallel plate capacitor 140 is attached to the substrate 110, and the upper surface is attached to the lower surface of the second piezoelectric layer 142. The upper surface of the second piezoelectric layer 142 is then attached to the lower surface of the second top electrode 143.

[0036] The orthographic projection of the overlapping area of the first bottom electrode 131, the first piezoelectric layer 132, and the first top electrode 133 on the substrate 110 is located within the acoustic wave reflection structure 120, while the orthographic projection of the overlapping area of the second bottom electrode 141, the second piezoelectric layer 142, and the second top electrode 143 on the substrate 110 is located outside the acoustic wave reflection structure 120.

[0037] Optionally, please refer to Figure 3 , one end of the planar inductor 150 is connected to the first bottom electrode 131 or the first top electrode 133, and the other end of the planar inductor 150 is connected to the second bottom electrode 141 or the second top electrode 143.

[0038] Exemplarily, one end of the planar inductor 150 is connected to the first bottom electrode 131, and the other end of the planar inductor 150 is connected to the second bottom electrode 141.

[0039] Optionally, the acoustic wave reflection structure 120 is a cavity provided on the upper surface of the substrate 110. The thin film bulk acoustic wave resonator 130 covers the cavity, and the cavity is filled with air to reflect acoustic waves.

[0040] In the foregoing embodiment, the specific structure of the planar inductor 150 is not limited as long as the planar inductor 150 is a planar structure and adheres to the surface of the substrate 110. Hereinafter, several optional structural forms of the planar inductor 150 are given.

[0041] Optionally, the planar inductor 150 is a zigzag inductor.

[0042] That is to say, the planar inductor 150 is divided into multiple segments, each segment is a straight line segment, and the multiple straight line segments are not on the same straight line and are connected end to end in sequence.

[0043] Optionally, the planar inductor 150 includes a first straight portion 151 and a second straight portion 152 perpendicular to the first straight portion 151. Both ends of the second straight portion 152 are respectively connected to two first straight portions 151. Both ends of the first straight portion 151 located in the middle position are respectively connected to two second straight portions 152. For the two first straight portions 151 located at the edge positions, both ends of one first straight portion 151 are respectively connected to the thin film bulk acoustic wave resonator 130 and the second straight portion 152, and both ends of the other first straight portion 151 are respectively connected to the parallel plate capacitor 140 and the second straight portion 152.

[0044] Optionally, the length direction of the first straight portion 151 is parallel to the sequential arrangement direction of the thin film bulk acoustic wave resonator 130 and the parallel plate capacitor 140.

[0045] Correspondingly, the length direction of the second straight portion 152 is perpendicular to the sequential arrangement direction of the thin film bulk acoustic wave resonator 130 and the parallel plate capacitor 140. With such an arrangement, it is convenient to connect the planar inductor 150 to the thin film bulk acoustic wave resonator 130 and the parallel plate capacitor 140.

[0046] Optionally, the number of both the first straight portions 151 and the second straight portions 152 is multiple, and the lengths of the multiple second straight portions 152 are not completely equal.

[0047] Adjusting the length of the first straight portion 151 or the second straight portion 152 can adjust the inductance value of the planar inductor 150. However, since the length direction of the first straight portion 151 is parallel to the sequential arrangement direction of the thin film bulk acoustic wave resonator 130 and the parallel plate capacitor 140, the setting of the length of the first straight portion 151 is restricted by the distance between the thin film bulk acoustic wave resonator 130 and the parallel plate capacitor 140. Therefore, it is more convenient and flexible to adjust the inductance value of the planar inductor 150 by adjusting the length of the second straight portion 152.

[0048] Exemplarily, the lengths of the second straight portions 152 located in the middle position are equal, and the lengths of the two second straight portions 152 located at the edge positions are less than the lengths of the second straight portions 152 located in the middle position.

[0049] Optionally, the lengths of the multiple first straight portions 151 are equal.

[0050] On the other hand, an embodiment of the present application provides a wireless communication device, including the bulk acoustic wave filter 100 with integrated IPD as described in any one of the above.

[0051] This wireless communication device has the same structure and beneficial effects as the bulk acoustic wave filter 100 with integrated IPD in the foregoing embodiments. The structure and beneficial effects of the bulk acoustic wave filter 100 with integrated IPD have been described in detail in the foregoing embodiments, and will not be elaborated herein.

[0052] The above are only preferred embodiments of the present application and are not intended to limit the present application, which may have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included within the protection scope of the present application.

Claims

1. A bulk acoustic wave filter integrating IPD, characterized in that, Comprising: A substrate, an acoustic wave reflection structure disposed within the substrate, and a thin film bulk acoustic resonator, a parallel plate capacitor, and a planar inductor attached to the surface of the substrate. The thin film bulk acoustic resonator is located above the acoustic wave reflection structure, and the planar inductor is electrically connected to the thin film bulk acoustic resonator and the parallel plate capacitor respectively.

2. The bulk acoustic wave filter integrating IPD according to claim 1, wherein The thin film bulk acoustic resonator includes a first bottom electrode, a first piezoelectric layer stacked on a side of the first bottom electrode away from the substrate, and a first top electrode. The parallel plate capacitor includes a second bottom electrode, a second piezoelectric layer stacked on a side of the second bottom electrode away from the substrate, and a second top electrode.

3. The bulk acoustic wave filter integrating IPD according to claim 2, wherein One end of the planar inductor is connected to the first bottom electrode or the first top electrode, and the other end of the planar inductor is connected to the second bottom electrode or the second top electrode.

4. The bulk acoustic wave filter integrated with IPD according to claim 1, wherein The planar inductor is a folded line inductor.

5. The bulk acoustic wave filter integrated with IPD according to claim 4, wherein The planar inductor includes a first straight portion and a second straight portion perpendicular to the first straight portion. Two ends of the second straight portion are respectively connected to two first straight portions, two ends of the first straight portion are respectively connected to two second straight portions, or two ends of the first straight portion are respectively connected to the thin film bulk acoustic resonator and the second straight portion, or two ends of the first straight portion are respectively connected to the parallel plate capacitor and the second straight portion.

6. The bulk acoustic wave filter integrating IPD according to claim 5, characterized in that, The length direction of the first straight portion is parallel to the sequential arrangement direction of the thin film bulk acoustic resonator and the parallel plate capacitor.

7. The bulk acoustic wave filter integrated with IPD according to claim 6, characterized in that The number of the first straight portions and the second straight portions is multiple, and the lengths of the multiple second straight portions are not completely equal.

8. The bulk acoustic wave filter integrated with IPD according to claim 6, characterized in that, The lengths of the multiple first straight portions are equal.

9. The bulk acoustic wave filter integrated with IPD according to claim 1, wherein The acoustic wave reflection structure is a cavity disposed on the upper surface of the substrate.

10. A wireless communication device, characterized in that, Comprising a bulk acoustic wave filter with integrated IPD as described in any one of claims 1 to 9.

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