Resonator and filter of heterogeneous integrated passive device

Abstract

The invention discloses a resonator and a filter of a heterogeneous integrated passive device. The resonator comprises a plurality of connected film bulk acoustic wave devices, the film bulk acoustic wave device comprises a cover plate, and a first passive device is heterogeneously integrated on the cover plate; the first passive devices heterogeneously integrated on the cover plate of the film bulk acoustic wave device are connected to obtain the combined passive device, so that the resonator is electrically connected with the combined passive device. The resonator is relatively high in integration level, and relatively large or combined passive devices can be obtained, so that the passive devices with required performance can be obtained.

Description

Technical Field

[0001] The invention relates to the technical field of MEMS devices, and in particular to a resonator and a filter of a heterogeneous integrated passive device. Background Art

[0002] The demand for high-speed and accurate information transmission in the 5G era has put forward higher requirements for communication systems. The RF front-end devices and modules at the physical layer play an increasingly important role in ensuring high-speed, accurate and low-loss information transmission. Filters play a core role in all aspects of the communication system, and thin-film bulk acoustic wave resonance is gradually occupying the RF front-end market with its high quality factor, low loss, high electromechanical coupling coefficient, high rectangular coefficient and applicability to the 5G frequency band.

[0003] However, low-order filters cannot meet the needs of most scenarios due to their out-of-band suppression, and high-order filters increase the area required for device preparation and cause the insertion loss in the band to deteriorate. In the previously proposed solution, adding several double-zero structures to the bulk acoustic wave filter can effectively solve the problem of bulk acoustic wave bandpass filter circuits that need to provide high adjacent-band suppression. However, when the inductor is introduced by external inductor or substrate, the device volume and preparation cost will be increased.

[0004] The invention patent application with publication number CN111510099A discloses a thin film bulk acoustic wave filter and a wafer-level packaging method thereof. The technical solution of the present invention has a cover plate bonded and fixed on the upper surface of the chip substrate to package and protect the resonant device. There is an air cavity under the resonant film, and there is a gap between the cover plate and the resonant device to ensure the normal operation of the resonant device. By setting a through-hole interconnect structure (TSV) in the chip substrate, the electrical connection lead-out of the resonant device on the upper surface of the chip substrate on the lower surface and the electrical connection with the redistribution interconnect structure (RDL) on the lower surface can be achieved. Compared with the existing packaging solutions, the technical solution of the present invention not only reduces the bonding alignment accuracy requirements between the device wafer and the packaging wafer, and reduces the chip packaging size, but also can conduct the heat generated by the operation of the resonant device to the outside of the filter through the through-hole interconnect structure, thereby accelerating the heat dissipation of the device and improving the heat dissipation efficiency.

[0005] The invention patent application with publication number CN111555732A discloses a thin film bulk acoustic wave device packaging structure and a packaging method thereof, belonging to the technical field of thin film bulk acoustic wave filter wafer packaging; the packaging structure includes a silicon wafer, an organic photosensitive film support wall and an organic photosensitive film cover plate, and a functional chip with a film layer structure is formed above the silicon wafer; upwardly protruding pad electrodes are formed at the two shoulders of the functional chip; an organic photosensitive film support wall is installed around the pad electrode, and the organic photosensitive film support wall is connected to the silicon wafer by thermal curing; a functional area lower cavity is provided directly below the functional chip; an organic photosensitive film cover plate is installed above the organic photosensitive film support wall, thereby forming a functional area upper cavity above the functional chip; electrode holes with the same center but different diameters are provided on the organic photosensitive film cover plate and the organic photosensitive film support wall, and metal is plated in the electrode holes.

[0006] However, the thin film bulk acoustic wave devices disclosed in the above two patents are mainly electrically connected to the passive inductor by external connection. Therefore, the filter constructed by the above thin film bulk acoustic wave devices has low integration and poor flexibility. Summary of the invention

[0007] The present invention provides a resonator of a heterogeneous integrated passive device, which has a high integration level and can obtain a larger or combined passive device to obtain a passive device with required performance.

[0008] The present invention provides a resonator of a heterogeneously integrated passive device, the resonator comprising a plurality of connected thin film bulk acoustic wave devices, the thin film bulk acoustic wave device comprising a cover plate, a first passive device being heterogeneously integrated on the cover plate; A combined passive device is obtained by connecting the heterogeneously integrated first passive devices on the cover plates of the thin film bulk acoustic wave devices, thereby achieving electrical connection between the resonator and the combined passive device.

[0009] In order to solve the problem that the volume of the filter is difficult to reduce due to the introduction of inductance in the bulk acoustic wave bandpass filter circuit with high adjacent-band suppression in the prior art, the present invention heterogeneously integrates passive devices on the top of the cover plate, and through flexible combination and deployment, passive devices with required performance are obtained in a suitable area, with good integration.

[0010] Since the passive inductor provided by the present invention is located on the top of the cover plate, it not only reduces the huge cost of introducing the passive inductor into the substrate, but also greatly reduces the overall volume of the device compared to the external inductor or substrate bonding method, thereby realizing the miniaturization of the thin film bulk acoustic wave device.

[0011] Preferably, the thin film bulk acoustic wave device further comprises a substrate, a piezoelectric oscillator stack and a pad: A first cavity is formed inside the substrate; The piezoelectric oscillation stack is located on the substrate and covers the first cavity; The cover plate is located above the piezoelectric oscillator stack, and a second cavity is provided between the cover plate and the piezoelectric oscillator stack, and a first passive device is heterogeneously integrated on the top of the cover plate; The pad is connected to the piezoelectric oscillation stack by passing through the first common welding point and the common electrode of the cover plate, and is used to lead out the electrode of the piezoelectric oscillation stack.

[0012] Preferably, the film bulk acoustic wave device further comprises a placement window and a second passive device: The placement window is composed of a third cavity and a fourth cavity connected to each other, the third cavity is located inside the substrate, and the fourth cavity runs through the inside of the piezoelectric oscillation stack; The second passive component is located between the cover plate and the placement window.

[0013] Since the first passive device provided by the present invention is located on the top of the cover plate rather than at the passive device position inside the cover plate, the area available for preparing the first passive device is increased. In one embodiment, the first passive device is an inductor, which increases the usable inductance value and avoids the situation in which the passive device fails due to the huge pressure generated during the packaging revision and the bonding and compaction process of the thin film bulk acoustic wave device.

[0014] Preferably, the second passive device comprises a bottom electrode, a dielectric layer and a top electrode, wherein: The bottom electrode is located at the bottom of the cover plate, and the bottom electrode and the second electrode of the piezoelectric oscillation stack are connected to the pad via a common electrode, thereby leading out the bottom electrode; The dielectric layer is located at the bottom of the bottom electrode; The top electrode is located at the bottom of the dielectric layer, and the top electrode is connected to the pad through a second common solder joint, so that the top electrode is led out, and the bottom of the top electrode is located at the top of the placement window.

[0015] Preferably, the first cavity is spaced apart from the placement window.

[0016] Preferably, the second passive component is a capacitor.

[0017] Preferably, the bottom of the cover plate is not etched, and the top of the cover plate is ground. Since the bottom of the cover plate where the second passive device is deposited is not etched, the influence of the uneven surface caused by the silicon pillars formed by etching on the deposited second passive device is avoided.

[0018] Preferably, the piezoelectric oscillator stack comprises a first electrode, a piezoelectric layer, a second electrode and a protective layer; The first electrode is located on the substrate and covers the first cavity, and the first electrode is connected to the pad via a common electrode, so that the first electrode is led out; The piezoelectric layer is located on the first electrode and the substrate; The second electrode is located on the piezoelectric layer, and the second electrode is connected to the pad via a common electrode, so that the second electrode is led out; The protection layer is located on the second electrode.

[0019] Preferably, the first passive component is a passive inductor. The present invention heterogeneously integrates a passive inductor on the outer side of the cover plate, and connects multiple heterogeneously integrated inductors, which is conducive to the production of large inductors and multiple inductors.

[0020] On the other hand, the present invention further provides a filter, comprising a series trunk and a plurality of parallel branches, wherein the parallel branches are connected between the series trunk and a ground line; The series trunk circuit includes a plurality of series bulk acoustic wave resonators connected in series in sequence; At least one series BAW resonator is spaced between the parallel branches, and the parallel branches include parallel BAW resonators connected in series; At least one of the series BAW resonator or the parallel BAW resonator is replaced with the resonator of the heterogeneous integrated passive device to achieve electrical connection between the series BAW resonator or the parallel BAW resonator and the combined passive device.

[0021] Compared with the prior art, the present invention has the following beneficial effects: The resonator provided by the present invention includes a plurality of thin film bulk acoustic wave devices with a first passive device heterogeneously integrated on a cover plate. Since the first passive device is integrated on the cover plate of the thin film bulk acoustic wave device, compared with the existing external connection and setting of a substrate to introduce passive devices, the size is significantly reduced, the integration is high, and the first passive device can be flexibly controlled by making different layouts of the thin film bulk acoustic wave device, so that the filter can be electrically connected to the required combined passive device. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 A schematic structural diagram of a thin film bulk acoustic wave device of a cover plate heterogeneously integrated passive device provided by a specific embodiment of the present invention; Figure 2a The etching step of the cavity and reserved window of the BAW part on the silicon substrate provided in the specific embodiment of the present invention; Figure 2b The step of depositing a sacrificial layer of a BAW part provided in a specific embodiment of the present invention; Figure 2c The steps of depositing and etching the first electrode of the BAW part provided in a specific embodiment of the present invention; Figure 2d The deposition step of the piezoelectric layer of the BAW part provided in the specific embodiment of the present invention; Figure 2eThe steps of depositing the second electrode and the protective layer of the BAW part provided in the specific embodiment of the present invention; Figure 2f The etching step of the BAW partial protective layer provided in the specific embodiment of the present invention; Figure 2g The etching step of the piezoelectric layer of the BAW part provided in the specific embodiment of the present invention; Figure 2h The step of depositing the first metal pad layer of the BAW part provided in a specific embodiment of the present invention; Figure 2i A step of releasing a portion of the sacrificial layer of the BAW provided in a specific embodiment of the present invention; Figure 2j The step of depositing the bottom electrode of the passive device of the cover part provided by the specific embodiment of the present invention; Figure 2k The step of depositing the dielectric layer of the passive device of the cover part provided by the specific embodiment of the present invention; Figure 2l The etching step of the cavity area of ​​the cover plate provided in the specific embodiment of the present invention; Figure 2m The etching step of the TSV through hole of the cover part provided by the specific embodiment of the present invention; Figure 2n The steps of depositing the solder joints of the cover plate and the top electrode of the passive device provided in the specific embodiment of the present invention; Figure 2o A step of bonding a substrate with a BAW device and a package cover with a passive device provided in a specific embodiment of the present invention; Figure 2p The steps of grinding to expose the TSV through hole and electroplating to fill it are provided in a specific embodiment of the present invention. Figure 2q The steps for preparing the cover inductor provided in the specific embodiment of the present invention; Figure 3a A schematic diagram of a bulk acoustic wave bandpass filter circuit with high adjacent band suppression provided by a specific embodiment of the present invention; Figure 3b An S-curve simulation diagram of a bulk acoustic wave bandpass filter circuit with high adjacent-band suppression provided by a specific embodiment of the present invention; Figure 3c A top schematic diagram of a resonator of a heterogeneous integrated passive device provided in a specific embodiment of the present invention, wherein a passive inductor L1 is connected in series; Figure 3d A schematic diagram of the top of a cover substrate of a resonator of a heterogeneous integrated passive device provided in a specific embodiment of the present invention, wherein a passive inductor L1 is connected in series; Figure 3eA top schematic diagram of a resonator of a heterogeneous integrated passive device provided by a specific embodiment of the present invention, wherein a passive inductor L2 is connected in parallel; Figure 3f A schematic diagram of the top of a cover substrate of a resonator of a heterogeneous integrated passive device provided by a specific embodiment of the present invention, wherein a passive inductor L2 is connected in parallel; Figure 3g A three-dimensional model effect diagram of a filter of a heterogeneous integrated passive device provided in a specific embodiment of the present invention; Figure 3h A three-dimensional filter model of a heterogeneous integrated passive device provided in a specific embodiment of the present invention focuses on displaying the BAW part effect diagram; Figure 3i A three-dimensional model of a filter of a heterogeneous integrated passive device provided in a specific embodiment of the present invention focuses on displaying the rendering of the cover plate part.

[0023] Among them, 100 is a substrate, 101 is a first cavity, 101-1 is a portion of the substrate where a window is placed, 102, 102-1 are filled sacrificial layers, 103 is a first electrode of a BAW (thin film bulk acoustic wave device) device, 104 is a piezoelectric layer, 105 is a second electrode of the BAW device, 106 is a protective layer, 107 is a protective layer window, 108 is a window for exposing the BAW first electrode, 108-1 is a sacrificial layer release hole for preparing the first cavity, 108-2 is a portion of the piezoelectric layer where a window is placed, i.e., a fourth cavity, 109 is a first metal PAD layer, 109-1 is a second metal PAD layer, 109-2 is a third metal PAD layer, 110 is a first cavity, 110-1 is a third cavity, 200, 200-1, 200-2 and 200-3 are cover plates, 201 is a bottom electrode of a passive device, 202 is a dielectric layer of a passive device, 203 is a second cavity, 204, 204-1 and 204-2 are TSV through holes, 205, 205-1 and 250-2 are respectively a third solder joint, a second solder joint and a first solder joint formed after filling TSV, 205-3 is a top electrode, 301, 301-1 and 301-2 are a first common solder joint, a common electrode and a second common solder joint formed by bonding the cover plate and the thin film bulk acoustic wave device, 302, 302-1 and 302-2 are a first solder pad, a second solder pad and a third solder pad, and 303, 303-1, 303-2, 303-3, 303-4 and 303-5 are pre-set patterns of the outer layer of the cover plate. DETAILED DESCRIPTION

[0024] The present invention is further described in detail below in conjunction with the embodiments and drawings. It should be pointed out that the embodiments described below are intended to facilitate the understanding of the present invention and do not have any limiting effect on the present invention.

[0025] A specific embodiment of the present invention provides a resonator of a heterogeneously integrated passive device, which includes a plurality of connected thin film bulk acoustic wave devices; the thin film bulk acoustic wave device includes a cover plate, on which a first passive device is heterogeneously integrated, and a combined passive device is obtained by connecting the first passive devices heterogeneously integrated on the cover plate. Since the connection method of the first passive devices constituting the combined passive device can be flexibly adjusted, a passive device with the required performance connected to the thin film bulk acoustic wave device can be flexibly obtained, and since the first passive device is integrated on the cover plate, the combined passive device occupies a smaller area and has better integration.

[0026] like Figure 1 As shown, the thin film bulk acoustic wave device of the cover heterogeneous integrated passive device provided by the specific embodiment of the present invention also includes a substrate 100, a piezoelectric oscillator stack, a first cavity 110 and a placement window 400. The piezoelectric oscillator stack is located on the substrate 100, and the first cavity 110 is located between the piezoelectric oscillator stack and the substrate 100. The placement window 400 is located in the area of ​​the thin film bulk acoustic wave device adjacent to the piezoelectric oscillator stack, and is obtained by etching the piezoelectric layer of the piezoelectric oscillator stack and the substrate located at the bottom of the piezoelectric layer, so that the placement window 400 is composed of the third cavity 110-1 of the substrate part of the placement window and the fourth cavity 108-2 of the piezoelectric layer part of the placement window.

[0027] The pad provided in the specific embodiment of the present invention is connected to the piezoelectric oscillator stack through a common electrode passing through the cover plate, and passes through the cover plate to lead out the electrode of the piezoelectric oscillator stack. The piezoelectric oscillator stack, the cover plate and the pad surround to form a second cavity 203.

[0028] The top of the cover plate 200 provided by the specific implementation of the present invention is ground and then heterogeneously integrated with a first passive device, and the bottom is connected to a second passive device. The second passive device at the bottom of the cover plate substrate is located at the top of the placement window 400, so that the top electrode 205-3, the dielectric layer 202 and the connected bottom electrode 201 of the passive device will not be subjected to excessive pressure during the bonding process, thereby avoiding the common electrode 301-1 connected to the bottom electrode 201 being connected to the top electrode 205-3, causing the passive device to fail; the first passive device at the top of the cover plate 200 is integrated on the outside of the cover plate, so that the first passive device can occupy a larger area to achieve greater performance. In one embodiment, the first passive device is a passive inductor. By heterogeneously integrating the passive inductor on the outside of the cover plate, the passive inductor can occupy a larger area to achieve a larger inductance value, and the passive device provided by the specific embodiment of the present invention does not increase the size, thereby achieving the miniaturization of the entire device.

[0029] The second passive device located at the bottom of the cover provided in a specific embodiment of the present invention includes a bottom electrode 201, a dielectric layer 202 and a top electrode 205-3. The bottom electrode 201 is located at the bottom of the cover 200 that has not been etched, thereby avoiding the influence of the uneven plane caused by the silicon pillars formed by etching on the deposited passive devices. The dielectric layer 202 is located between the top electrode 205-3 and the bottom electrode 201. The top electrode 205-3 is located at the top of the placement window. The top electrode 205-3 is formed by bonding with the metal pad layer to form a second common solder joint 301-2. The second common solder joint 301-2 is connected to the third solder pad 302-2 through a TSV through hole, thereby leading out the top electrode 205-3 of the passive device.

[0030] The passive device provided by the specific embodiment of the present invention, which is located on the top of the cover plate, includes an outer layer of the cover plate, and the outer layer can be used for preparing a predetermined pattern of the passive inductor so as to work in combination with the thin film bulk acoustic wave device.

[0031] The piezoelectric oscillator stack provided in a specific embodiment of the present invention includes a first electrode 103, a second electrode 105, a piezoelectric layer 104 and a protective layer 106; wherein the first electrode 103 is located on the first cavity 110, the piezoelectric layer 104 is located on the first electrode 103 and the substrate 100, the second electrode 105 is located on the piezoelectric layer 100, and the protective layer 106 is located on the second electrode 105.

[0032] The thin film bulk acoustic wave device provided in a specific embodiment of the present invention also includes a metal pad layer, which includes a first metal pad layer 109, a second metal pad layer 109-1 and a third metal pad layer 109-2; the first metal pad layer 109 is connected to the first electrode 103; the second metal pad layer 109-1 is connected to the second electrode 105; the third metal pad layer 109-2 is located on the piezoelectric layer 104; and a window 400 is placed to separate the second metal pad layer 109-1 and the third metal pad layer 109-2.

[0033] The cover provided by the specific embodiment of the present invention further includes a plurality of TSV through holes penetrating the cover, a first solder joint 205-2, a second solder joint 205-1 and a third solder joint 205 led out from the corresponding TSV through holes, and a second cavity 203 opened at the bottom of the cover.

[0034] The first solder joint 205 - 2 provided in the specific embodiment of the present invention is bonded to the first metal pad layer 109 to form a first common solder joint 301 . The first common solder joint 301 leads the first electrode 103 out through the corresponding TSV through hole and connects to the first solder pad 302 .

[0035] The second solder joint 205-1 provided in the specific embodiment of the present invention is bonded to the second metal pad layer 109-1, so that the second electrode 105 is connected to the bottom electrode 201 of the passive device to construct a first common electrode 301-1, and the second common electrode 301-1 leads the second electrode 105 out through the corresponding TSV through hole and connects to the second solder pad 302-1.

[0036] The third solder joint 205 provided in the specific embodiment of the present invention is connected to the top electrode 205-3 of the second passive device and the third metal pad layer to form a second common solder joint 301-2. The second common solder joint 301-2 leads the top electrode 205-3 of the second passive device out through the corresponding TSV through hole and connects to the third solder pad 302-2.

[0037] The second cavity 203 provided in the specific embodiment of the present invention is located on the top of the protective layer 106, so that the thin film bulk acoustic wave device provided in the specific embodiment of the present invention can work.

[0038] The cover plate and substrate provided in the specific embodiment of the present invention can be one of silicon, silicon carbide, sapphire, ceramic, etc. or any combination thereof; the cavity required for the operation of the thin film bulk acoustic wave device, the cross section of the cavity can be one of trapezoidal, triangular, rectangular and square or any combination thereof, the lateral width is 40-2000μm, and the depth is 1μm-20μm; the metal pad layer and the electrode are deposited by thermal evaporation or magnetron sputtering, and the material can be one of molybdenum, gold, platinum, copper, aluminum, silver, titanium, tungsten, nickel or any combination thereof, with a thickness of 50-12000nm; plasma etching, lift-off, wet etching and other processes are used. Forming a pattern; the outer layer of the cover plate can be made of one or any combination of molybdenum, gold, platinum, copper, aluminum, silver, titanium, tungsten, and nickel, with a thickness of 50nm-2000nm; the passive device of the outer layer of the cover plate can be any winding pattern, including but not limited to one or more combinations of bent line inductors, square spiral inductors, circular spiral inductors, and octagonal spiral inductors; the piezoelectric layer can be made of one or any combination of aluminum nitride, scandium-doped aluminum nitride, lead zirconate titanate (PZT), lithium niobate, etc., with a thickness of 100-3000nm; the electrode protection layer can be made of one or any combination of aluminum nitride, scandium-doped aluminum nitride, etc., with a thickness of 20-300nm; the dielectric layer can be made of one or any combination of aluminum nitride, doped aluminum nitride, silicon oxide, doped silicon oxide, silicon nitride, doped silicon nitride, etc., with a thickness of 20-500nm.

[0039] A specific embodiment of the present invention further provides a method for preparing a thin film bulk acoustic wave device of a cover plate heterogeneous integrated passive device, comprising: like Figure 2aAs shown, the substrate 100 is ultrasonically cleaned with an SPM solution, and a first cavity 101 and a reserved window 101-1 for placing a passive device are formed on the silicon substrate 100 by a dry etching process. The cavity etching process is RF power 800 / 300W, chamber pressure 8mT, etching gas SF6 / O2 flow rate 200 / 50sccm, etching rate of about 0.8μm / min, the first cavity 101 and the reserved window 101-1 for placing a passive device have lateral widths of 200μm and 150μm, respectively, and a depth of 3.5μm.

[0040] like Figure 2b As shown, phosphorus-containing silicon oxide (PSG) is deposited on the substrate 100 by a PECVD method, and then treated by CMP to form sacrificial layer filling 102, 102-1 with a dishing thickness less than 30nm at 101, 101-1.

[0041] like Figure 2c As shown, 150nm of metal molybdenum (Mo) is deposited on the substrate 100 and the sacrificial layer by thermal evaporation or magnetron sputtering, and the first electrode 103 of the BAW device is formed by dry etching. The etching process of the first electrode 103 is RF power 600 / 60W, chamber pressure 6mT, etching gas SF6 / O2 flow rate 70 / 60sccm, etching rate of about 100nm / min, and the lateral width of the first electrode 103 of the BAW device is 300μm.

[0042] like Figure 2d As shown, a 350 nm scandium-doped aluminum nitride (AlScN) piezoelectric layer 104 is deposited on the substrate 100, the first electrode 103, and the sacrificial layer by magnetron sputtering or MOCVD.

[0043] like Figure 2e As shown, 200nm of metal molybdenum (Mo) and 100nm of protective layer aluminum nitride (AlN) are deposited on the surface of the piezoelectric layer 104 by magnetron sputtering or MOCVD. The second electrode 105 and the protective layer 106 of the BAW device are formed by dry etching. The etching process of the protective layer 106 is RF power 500 / 100W, chamber pressure 8Mt, etching gas Cl2 / Ar flow rate 100 / 20sccm, and etching rate is about 300nm / min. The etching process of the second electrode 105 is RF power 600 / 60W, chamber pressure 6mT, etching gas SF6 / O2 flow rate 70 / 60sccm, etching rate is about 100nm / min, and the lateral width of the second electrode 105 of the BAW device is 300μm.

[0044] like Figure 2fAs shown, the protective layer 106 is dry-etched to form a window 107 exposing the second electrode 105 of the BAW device. The etching process is the same as the etching process for forming the protective layer 106, and the lateral width of the window 107 is 50 μm.

[0045] like Figure 2g As shown, the piezoelectric layer 104 is dry-etched to form a window 108 exposing the first pole 103 of the BAW device, a release hole 108-1, and a piezoelectric layer portion 108-2 for preparing the window. The etching process of the piezoelectric layer 104 is RF power 800 / 20W, chamber pressure 5mT, etching gas Cl2 / BCl3 flow rate 60 / 180sccm, etching rate about 90nm / min, the lateral widths of the windows 108 and 108-2 are 50μm and 150μm respectively, and the release hole 108-1 is not in the same cross section, which is indicated by a dotted line.

[0046] like Figure 2h As shown, 1.2 μm gold is deposited on the piezoelectric layer 104, the protective layer 106 and the windows 108-1 and 107 by thermal evaporation or magnetron sputtering, and a first metal pad layer 109, a second metal pad layer 109-1 and a third metal pad layer 109-2 are formed by dry etching or wet etching. The first metal pad layer 109 is not connected to the BAW second electrode 105.

[0047] like Figure 2i As shown, a sacrificial layer release hole 108-1 is prepared for the first cavity and the sacrificial layer is etched to prepare a piezoelectric layer portion 108-2 for placing a window, thereby forming a first cavity 110 and a substrate portion 110-1 for placing a window.

[0048] like Figure 2j As shown, 200nm of metal molybdenum (Mo) is deposited on the cover substrate 200 by thermal evaporation or magnetron sputtering, and dry etching is used to form the bottom electrode 201 of the passive device (capacitor and inductor or any combination thereof) inside the cover. The etching process of the bottom electrode 201 of the passive device is RF power 600 / 60W, chamber pressure is 6mT, etching gas SF6 / O2 flow rate is 70 / 60sccm, etching rate is about 100nm / min, and the lateral width of the bottom electrode 201 of the passive device is 100μm.

[0049] like Figure 2kAs shown, a 70nm silicon nitride film is deposited on the surface of the cover substrate 200 and the electrode 201 by magnetron sputtering or PECVD, and a dielectric layer 202 of a passive device (capacitor and inductor or any combination thereof) is formed by dry etching. The etching process of the dielectric layer 103 is RF power 650 / 200W, chamber pressure 15mT, etching gas CF4 / O2 flow rate 200 / 30sccm, etching rate about 150nm / min, and the lateral width of the dielectric layer 103 is 80μm.

[0050] like Figure 2l As shown, a second cavity 203 is formed on the cover substrate 200 by dry etching. The etching process of the second cavity 203 is RF power 800 / 300W, chamber pressure 8mT, etching gas SF6 / O2 flow rate 200 / 50sccm, etching rate about 0.8μm / min, and the second cavity depth is 7μm.

[0051] like Figure 2m As shown, TSV through holes 204, 204-1 and 204-2 are etched on the cover substrate 200 using the Bosch process. The Bosch etching process has an RF power of 3000 / 250W, a chamber pressure of 4mT, an etching gas O2 / SF6 flow rate of 80 / 240sccm, and an etching rate of about 8μm / min. The depth of the TSV through holes 204, 204-1 and 204-2 is 140μm.

[0052] like Figure 2n As shown, 1.2 μm of gold is deposited on the cover substrate 200 by thermal evaporation or magnetron sputtering, and the third solder joint 205, the second solder joint 205-1, the first solder joint 205-2 and the top electrode 205-3 of the passive device (capacitor and inductor or any combination thereof) are formed by dry etching or wet etching. 205 is the metal filled in the through-holes of the cover and 204 and connected to the top electrode 205-3 of the passive device, 205-1 is the metal filled in the through-holes of the cover and 204-1 and connected to the lower electrode of the passive device but not connected to the top electrode 205-3, 205-2 is the metal filled in the through-holes of the cover and 204-2, 205-3 is the filling metal deposited on the dielectric layer 203, connected to 205 but not connected to 205-1, and the lateral width of the top electrode 205-3 is controlled to form a passive device (capacitor and inductor or any combination thereof) of the required area.

[0053] like Figure 2oAs shown, a substrate 100 with a BAW device is bonded to a package cover with passive devices (capacitors and inductors or any combination thereof) by a gold-gold bonding method, a first metal pad layer 109 is bonded to a first solder joint 205-2 to form a first common solder joint 301, a second metal pad layer 109-1 is bonded to a second solder joint 205-1 to form a common electrode 301-1, and a third metal pad layer 109-2 is bonded to a third solder joint 205 to form a second common solder joint 301-2.

[0054] like Figure 2p As shown, the top of the bonded chip cover 200 is removed by mechanical grinding to form cover plates 200 - 1 , 200 - 2 , and 200 - 3 , exposing the metal deposited in the TSV holes, and then the TSV through holes are filled by electroplating.

[0055] like Figure 2q As shown, 1.2 μm of gold is deposited on the top of the cover plate 200 after grinding by thermal evaporation or magnetron sputtering, and a passive inductor having a predetermined pattern of cover plate outer layers 303, 303-1, 303-2, 303-3, 303-4 and 303-5, a first pad 302, a second pad 302-1, and a third pad 302-2 is formed by dry etching or wet etching.

[0056] A specific embodiment of the present invention provides a bulk acoustic wave bandpass filter circuit with high adjacent band suppression and a top schematic diagram of each part combined with the present invention, including: The ladder-type bulk acoustic wave filter 401 constructed in the specific embodiment of the present invention is composed of four series-connected thin film bulk acoustic wave resonators 402 and four parallel-connected thin film bulk acoustic wave resonators 403. By connecting a passive inductor L1 in series with one of the parallel resonators, an extra zero point is added to achieve high adjacent band suppression of the original circuit, such as Figure 3a , where L2 is only used as a location diagram of the subsequent embodiments and does not play a role in the circuit. Figure 3b In the figure, curve 1 is the circuit S-curve simulation diagram without external passive devices, and curve 2 is the circuit S-curve simulation diagram after adding passive inductor L1. It can be seen that the curve after external passive inductor has higher adjacent band suppression.

[0057] When manufacturing the ladder-type bulk acoustic wave filter 401 in a specific embodiment of the present invention, for the entire device after bonding, Figure 3c , Figure 3e This is a schematic diagram of the BAW section viewed from the top. Figure 3d and Figure 3fThis is a schematic diagram observed from the top of the substrate of the cover plate; the octagons distributed around are the bonding sites between the cover plate and the BAW device, and the vacant area outside the pads on the outer layer of the cover plate can be used for the production of passive devices. Here, the implementation methods of series and parallel passive inductance at the parallel resonator 403 are respectively shown, where Figure 3c and Figure 3d For example, Figure 3 e and Figure 3 e are examples of series passive inductor L1. Figure 3f This is an example of a parallel passive inductor L2. This specific embodiment shows that the resonator provided by the present invention has good integration and flexibility.

[0058] The specific implementation of the present invention additionally provides a three-dimensional model view of the filter based on the above technology. Figure 3g To show the overall effect of the model, Figure 3h The model focuses on the BAW effect. Figure 3i The model focuses on the effect of the cover. Among them, 404-1, 404-2, 404-3, 404-4 are series resonators, 405-1, 405-2, 405-3, 405-4 are parallel resonators, C1 is a passive capacitor made of the cover, and L3 is a passive inductor made of the outer layer of the cover. Figure 3g-Figure 3i It can be clearly seen from the three-dimensional diagram that the passive inductor heterogeneously integrated on the resonator provided by the specific embodiment of the present invention has a high degree of integration and a small size.

Claims

1. A resonator of a heterogeneous integrated passive device, characterized in that: The resonator comprises a plurality of connected thin film bulk acoustic wave devices, wherein the thin film bulk acoustic wave device comprises a cover plate, and a first passive device is heterogeneously integrated on the cover plate; The combined passive device is obtained by connecting the first passive devices heterogeneously integrated on the cover plates of the thin film bulk acoustic wave devices, thereby realizing electrical connection between the resonator and the combined passive device.

2. The resonator of heterogeneous integrated passive device according to claim 1, characterized in that: The thin film bulk acoustic wave device also includes a substrate, a piezoelectric oscillator stack and a pad: A first cavity is formed inside the substrate; The piezoelectric oscillation stack is located on the substrate and covers the first cavity; The cover plate is located above the piezoelectric oscillator stack, and a second cavity is provided between the cover plate and the piezoelectric oscillator stack, and a first passive device is heterogeneously integrated on the top of the cover plate; The pad is connected to the piezoelectric oscillation stack by passing through the first common welding point and the common electrode of the cover plate, and is used to lead out the electrode of the piezoelectric oscillation stack.

3. The resonator of heterogeneous integrated passive device according to claim 2, characterized in that: The film bulk acoustic wave device further includes a placement window and a second passive device: The placement window is composed of a third cavity and a fourth cavity connected to each other, the third cavity is located inside the substrate, and the fourth cavity runs through the inside of the piezoelectric oscillation stack; The second passive component is located between the cover plate and the placement window.

4. The resonator of heterogeneous integrated passive device according to claim 3, characterized in that: The second passive device comprises a bottom electrode, a dielectric layer and a top electrode, wherein: The bottom electrode is located at the bottom of the cover plate, and the bottom electrode and the second electrode of the piezoelectric oscillation stack are connected to the pad via a common electrode, thereby leading out the bottom electrode; The dielectric layer is located at the bottom of the bottom electrode; The top electrode is located between the dielectric layer and the placement window, and the top electrode is connected to the pad through the second common welding point, so that the top electrode is led out.

5. The resonator of heterogeneous integrated passive device according to claim 3, characterized in that: The placement window is spaced apart from the first cavity.

6. The resonator of heterogeneous integrated passive device according to claim 3, characterized in that: The second passive component is a capacitor.

7. The resonator of heterogeneous integrated passive device according to claim 3, characterized in that: The bottom of the cover plate is not etched, and the top of the cover plate is ground.

8. The resonator of heterogeneous integrated passive device according to claim 2, characterized in that: The piezoelectric oscillation stack comprises a first electrode, a piezoelectric layer, a second electrode and a protective layer; The first electrode is located on the substrate and covers the first cavity, and the first electrode is connected to the pad via a first common welding point, so that the first electrode is led out; The piezoelectric layer is located on the first electrode and the substrate; The second electrode is located on the piezoelectric layer, and the second electrode is connected to the pad via a common electrode, so that the second electrode is led out; The protection layer is located on the second electrode.

9. The resonator of heterogeneous integrated passive device according to claim 1, characterized in that: The first passive component is a passive inductor.

10. A filter, characterized in that: It includes a series trunk and a plurality of parallel branches, wherein the parallel branches are connected between the series trunk and a ground line; The series trunk circuit includes a plurality of series bulk acoustic wave resonators connected in series in sequence; At least one series BAW resonator is spaced between the parallel branches, and the parallel branches include parallel BAW resonators connected in series; At least one of the series BAW resonator or the parallel BAW resonator is replaced with a resonator of the heterogeneous integrated passive device as described in any one of claims 1 to 9 to achieve electrical connection between the series BAW resonator or the parallel BAW resonator and the combined passive device.

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