Bulk acoustic wave resonator with temperature compensation layer, filter, and electronic device

Abstract

The present application relates to a bulk acoustic wave resonator and a manufacturing method thereof, the resonator comprising: a substrate; an acoustic mirror; a bottom electrode; a top electrode; a piezoelectric layer disposed between the bottom electrode and the top electrode; a temperature compensation layer structure disposed between the bottom electrode and the piezoelectric layer, the temperature compensation layer structure comprising a temperature compensation layer, wherein: the resonator further comprises a protective layer; at a non-electrode connecting end of the top electrode, the protective layer covers an upper surface of the temperature compensation layer structure along at least a portion of a circumferential direction of the temperature compensation layer structure, a portion of the upper surface of the temperature compensation layer structure is exposed via an opening defined by an inner edge of the protective layer, the opening is at least partially within an active area of the resonator; and at the non-electrode connecting end of the top electrode, the inner edge of the protective layer is flush with or inward of the non-electrode connecting end of the top electrode in a horizontal direction. The present application also relates to a filter and an electronic device.

Description

Technical Field

[0001] Embodiments of the present invention relate to the field of semiconductors, and in particular to a bulk acoustic wave resonator, a filter having the resonator, and an electronic device. Background Art

[0002] With the increasing development of 5G communication technology, the requirements for communication frequency bands are becoming increasingly stringent. Traditional RF filters, due to structural and performance limitations, cannot meet the requirements of high-frequency communication. Film bulk acoustic resonator (FBAR), a new type of MEMS device, offers advantages such as small size, light weight, low insertion loss, wide bandwidth, and high quality factor. It is well suited to the upgrading of wireless communication systems, making FBAR technology a research hotspot in the communications field.

[0003] The main structure of a film bulk acoustic wave resonator is a "sandwich" structure consisting of electrodes, piezoelectric film, and electrodes, that is, a layer of piezoelectric material is sandwiched between two layers of metal electrodes. By inputting a sinusoidal signal between the two electrodes, the FBAR uses the inverse piezoelectric effect to convert the input electrical signal into mechanical resonance, and then uses the piezoelectric effect to convert the mechanical resonance into an electrical signal output. The film bulk acoustic wave resonator mainly uses the longitudinal piezoelectric coefficient of the piezoelectric film to produce the piezoelectric effect, so its main operating mode is the longitudinal wave mode in the thickness direction. That is, the sound waves of the bulk acoustic wave resonator are mainly within the thin film of the resonator, and the main vibration direction is in the longitudinal direction. However, due to the existence of boundaries, Lamb waves that are not perpendicular to the piezoelectric film layer will exist at the boundaries. At this time, the transverse Lamb waves will leak out from the lateral side of the piezoelectric film layer, resulting in acoustic loss, which reduces the Q value of the resonator.

[0004] In addition, BAW resonators generally have a negative frequency temperature drift coefficient, approximately -30ppm / °C. This is because the piezoelectric and electrode materials of BAW resonators have negative frequency temperature drift coefficients, which means that the stiffness of these materials decreases as the temperature rises. This decrease in stiffness causes the speed of sound to decrease. Based on the formula V = F*λ = F*2d (where V is the speed of sound, F is the frequency, λ is the wavelength, and d is the thickness of the corresponding stack), as the speed of sound decreases, the frequency decreases. Therefore, BAW resonators experience frequency drift as the temperature rises. However, as the temperature rises, the stiffness of SiO2 and positive temperature coefficient materials increases. Therefore, by adding layers of SiO2 and positive temperature coefficient materials, the decrease in stiffness of other materials, which causes the decrease in sound speed, is offset, thereby preventing frequency drift.

[0005] Figure 1 FIG is a cross-sectional schematic diagram of a bulk acoustic wave resonator in the prior art. Figure 1 As shown, the resonator includes a substrate 1, an acoustic mirror cavity 2, a seed layer 3, a bottom electrode 4, a seed layer 5, a temperature compensation layer 11, a piezoelectric layer 8, a top electrode 9 and a passivation layer 10.Figure 1 The thickness L1 of the bottom electrode, the thickness L2 of the piezoelectric layer, and the thickness L3 of the top electrode are shown in the middle.

[0006] In a conventional bulk acoustic wave resonator as shown in Figure 1 , the material of the temperature compensation layer 11, SiO2, is released under the action of HF without a protective layer, as shown in Figure 2 Figure 2 The SEM picture of the release of the temperature compensation layer in the prior art design. The release of the material of the temperature compensation layer 11 causes fluctuations in the electromechanical coupling coefficient of the resonator and changes in the area of the 50Ω resonator.

[0007] To prevent or reduce the release of the temperature compensation layer, a structure as shown in Figure 3 is proposed. Figure 3 The cross-sectional schematic diagram of the bulk acoustic wave resonator in the prior art, in which a layer of bottom electrode interlayer 12 covers the temperature compensation layer 11 to prevent the release of SiO2, but when the resonator has a small demand for the electromechanical coupling coefficient of the resonator, it causes the proportion of the thicknesses L1 and L3 of the electrodes and the thickness L2 of the piezoelectric layer to be imbalanced, i.e., (L1+L3) / L2 is much greater than 1, as shown in Figure 3 , which leads to a decrease in the performance of the resonator (see Figure 5 mentioned later). SUMMARY

[0008] To alleviate or solve at least one aspect of the above problems in the prior art, the present application is proposed.

[0009] According to an aspect of an embodiment of the present application, a bulk acoustic wave resonator is proposed, comprising:

[0010] a substrate;

[0011] an acoustic mirror;

[0012] a bottom electrode;

[0013] a top electrode;

[0014] a piezoelectric layer disposed between the bottom electrode and the top electrode;

[0015] a temperature compensation layer structure disposed between the bottom electrode and the piezoelectric layer, the temperature compensation layer structure comprising a temperature compensation layer,

[0016] wherein:

[0017] the resonator further comprises a protective layer;

[0018] ​at the non-electrode-connection end of the top electrode, the protective layer covers the upper surface of the temperature compensating layer structure along at least a portion of the circumferential direction of the temperature compensating layer structure, and a portion of the upper surface of the temperature compensating layer structure is exposed via an opening defined by the inner edge of the protective layer, the opening being at least partially within the effective area of the resonator; and

[0019] at the non-electrode-connection end of the top electrode, the inner edge of the protective layer is flush with or inside the non-electrode-connection end of the top electrode in the horizontal direction.

[0020] Embodiments of the present application also relate to a method of manufacturing a bulk acoustic wave resonator, the resonator comprising a substrate, an acoustic mirror, a bottom electrode, a top electrode, a piezoelectric layer disposed between the bottom electrode and the top electrode, a temperature compensating layer structure comprising a temperature compensating layer, the temperature compensating layer structure being disposed between the bottom electrode and the piezoelectric layer,

[0021] the method comprising the steps of:

[0022] forming the temperature compensating layer structure on the bottom electrode;

[0023] after forming the temperature compensating layer structure, disposing a protective layer such that:

[0024] at the non-electrode-connection end of the top electrode, the protective layer covers the upper surface of the temperature compensating layer structure along at least a portion of the circumferential direction of the temperature compensating layer structure, and a portion of the upper surface of the temperature compensating layer structure is exposed via an opening defined by the inner edge of the protective layer; and at the non-electrode-connection end of the top electrode, the inner edge of the protective layer is flush with or inside the non-electrode-connection end of the top electrode in the horizontal direction.

[0025] Embodiments of the present application also relate to a filter comprising the bulk acoustic wave resonator described above.

[0026] Embodiments of the present application also relate to an electronic device comprising the filter described above or the resonator described above. BRIEF DESCRIPTION OF DRAWINGS

[0027] The following description and drawings can better help understand these and other features and advantages of various embodiments disclosed by the present application, in which like reference numerals refer to like parts throughout the several views of the drawings in which:

[0028] Figure 1 is a cross-sectional schematic view of a bulk acoustic wave resonator in the prior art;

[0029] Figure 2 is a SEM picture of a temperature compensating layer being released in a prior design;

[0030] Figure 3 is a cross-sectional schematic view of a bulk acoustic wave resonator in the prior art, wherein a CM layer is disposed above the temperature compensating layer;

[0031] Figure 4 A cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present application;

[0032] Figure 5 An exemplary diagram showing the relationship between the width of the protective layer on the upper surface of the temperature compensating layer and the performance of the resonator is shown. Figure 3 The structure shown is compared with Figure 4 A performance comparison diagram of the resonator of the structure shown.

[0033] Figure 6 An exemplary diagram showing the relationship between the width of the protective layer on the upper surface of the temperature compensating layer and the performance of the resonator is shown.

[0034] Figures 7-8 A cross-sectional view of a bulk acoustic resonator according to an exemplary embodiment of the present application;

[0035] Figures 9-11 A top view of a bulk acoustic resonator according to an exemplary embodiment of the present application is shown.

[0036] Figures 12A-12F A series of cross-sectional views of a method of manufacturing the structure shown according to an exemplary embodiment of the present application is shown. Figure 4 A series of cross-sectional views of a method of manufacturing the structure shown according to an exemplary embodiment of the present application is shown. DETAILED DESCRIPTION

[0037] The technical solutions of the present application will be further described below by way of examples and with reference to the accompanying drawings. In the description, identical or similar reference numerals indicate identical or similar components. The following description of the embodiments of the present application with reference to the accompanying drawings is intended to explain the general inventive concept of the present application, and should not be construed as limiting the present application to one of the embodiments. The embodiments described below are only a part of the embodiments of the present application, and all other embodiments obtained by those skilled in the art based on the embodiments described in the present application are within the scope of protection of the present application.

[0038] First, the reference numerals in the drawings of the present application are explained as follows:

[0039] 1: substrate, optional materials are single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0040] 2: acoustic mirror, which can be a cavity, or a Bragg reflection layer and other equivalent forms. In the embodiments shown in the present application, a cavity is provided on the upper surface of the substrate. In optional embodiments, the cavity can also be located inside the substrate.

[0041] 3: first seed layer, optional materials are aluminum nitride, zinc oxide, PZT, etc. and rare earth element doped materials containing a certain atomic ratio of the above materials.

[0042] 4: bottom electrode, material can be selected: gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), titanium tungsten (TiW), aluminum (Al), titanium (Ti), osmium (Os), magnesium (Mg), gold (Au), tungsten (W), molybdenum (Mo), platinum (Pt), ruthenium (Ru), iridium (Ir), germanium (Ge), copper (Cu), aluminum (Al), chromium (Cr), arsenic doped gold and similar metals.

[0043] 5: second seed layer, which can be selected from aluminum nitride, zinc oxide, PZT and other materials and contains a certain atomic ratio of rare earth element doped materials.

[0044] 6: third seed layer, which can be selected from aluminum nitride, zinc oxide, PZT and other materials and contains a certain atomic ratio of rare earth element doped materials.

[0045] 7: protective layer, which can be a non-metallic material to prevent the temperature compensation layer from being etched or released, or a metallic material, the metallic material of the protective layer can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof, and the material of the metallic protective layer can be the same as that of the electrode.

[0046] 8: piezoelectric layer, which can be a single crystal piezoelectric material, which can be selected from single crystal aluminum nitride, single crystal gallium nitride, single crystal lithium niobate, single crystal lead zirconate titanate (PZT), single crystal potassium niobate, single crystal quartz film, or single crystal lithium tantalate, etc. It can also be a polycrystalline piezoelectric material (corresponding to single crystal, non-single crystal material), which can be selected from polycrystalline aluminum nitride, zinc oxide, PZT, etc. It can also be a rare earth element doped material containing a certain atomic ratio of the above materials, for example, it can be doped aluminum nitride, which contains at least one rare earth element such as scandium (Sc), yttrium (Y), magnesium (Mg), titanium (Ti), lanthanum (La), cerium (Ce), praseodymium (Pr), neodymium (Nd), promethium (Pm), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), ytterbium (Yb), lutetium (Lu), etc.

[0047] 9: top electrode, which can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof. The material of the top electrode is generally the same as that of the bottom electrode, but it can also be different.

[0048] 10: process layer, which is arranged on the top electrode of the resonator, and the process layer can be a mass adjustment load or a passivation layer, and the material thereof can be a dielectric material such as silicon dioxide, aluminum nitride, silicon nitride, etc.

[0049] 11: temperature compensation layer, the material of the temperature compensation layer 11 is a material opposite to the frequency temperature coefficient of the piezoelectric layer, which can be a positive temperature coefficient material such as polysilicon, borophosphate glass (BSG), silicon dioxide (SiO2), doped silicon dioxide (such as fluorine doping), chromium (Cr), or tellurium oxide (TeO(x)), etc. For example, the rigidity of a material such as SiO2 with a positive frequency temperature drift coefficient will increase with the increase of temperature, so the decrease of the acoustic velocity caused by the decrease of the rigidity of the ordinary resonator (without temperature compensation layer) with the increase of temperature can be compensated or reduced by increasing the layer of the material such as SiO2 with a positive frequency temperature drift coefficient (i.e. the temperature compensation layer), thereby reducing the negative drift of the frequency with the increase of temperature, and then the zero temperature drift or the frequency temperature drift coefficient within the range of ±5ppm / ℃ can be achieved by setting a suitable thickness of the temperature compensation layer.

[0050] 12: interlayer electrode, the material can be selected from molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite or alloy thereof.

[0051] In the present application, a protective layer structure is used to prevent the temperature compensation layer from being etched or released, and at the same time, the zero temperature drift performance can be achieved under the premise of ensuring the performance of the resonator. The following will be described with reference to specific examples.

[0052] Figure 4 A schematic cross-sectional view of a bulk acoustic wave resonator according to an example embodiment of the present application. Figure 4 In the present application, the protective structure for forming the temperature compensation layer is a protective ring structure (CP ring), as described below with reference to Figures 12A-12F which can be formed by deposition and etching of the film layer, and the process flow has high feasibility. The film deposition thickness is controllable and the θ angle of the CP ring after etching is controllable, which will not cause the fracture of the piezoelectric layer. In the present embodiment, the θ angle is required to be less than 90°, and the range of the θ angle is close to the angle of the end of the bottom electrode, for example, the degree of θ is 90%-110% of the degree of the included angle of the end of the non-electrode connecting end of the bottom electrode. More specifically, the inner edge of the CP ring or the protective layer 7 is a bevel, and the included angle between the bevel and the upper surface of the temperature compensation layer 11 is an acute angle θ, based on the bevel, as shown in Figure 4 the thickness of the protective layer 7 gradually increases from the inside to the outside. The above description of the angle can also be applied to other embodiments of the present application.

[0053] In Figure 4In the embodiment shown, the protective layer 7 is in the form of a CP ring. In other words, at the non-electrode connection end of the top electrode, the protective layer 7 covers at least a portion of the upper surface of the temperature compensating layer structure along the circumference of the temperature compensating layer structure, and a portion of the upper surface of the temperature compensating layer structure is exposed through an opening defined by the inner edge of the protective layer 7, and the opening is at least partially within the effective area of ​​the resonator. The "opening" here corresponds to the "ring" in the CP ring. As mentioned later, the CP ring or opening can be closed or non-closed. As can be understood and as will be described later Figures 7-8 As shown, when the temperature compensating layer 11 is also provided with a seed layer 6 , the temperature compensating layer structure includes the temperature compensating layer 11 and the seed layer 6 ; and when the seed layer 6 is not provided on the upper side of the temperature compensating layer 11 , the temperature compensating layer structure includes the temperature compensating layer 11 .

[0054] like Figure 4 As shown, at the non-electrode connection end of the top electrode, the inner edge of the protective layer 7 is horizontally inside the non-electrode connection end of the top electrode 9. As can be understood, the inner edge of the protective layer 7 can also be flush with the non-electrode connection end of the top electrode 9 in the horizontal direction.

[0055] exist Figure 4 In the embodiment, the upper side of the temperature compensation layer 11 is also covered with a third seed layer 6. Figure 4 In the embodiment shown, in the effective area of ​​the resonator, the protective layer 7 is actually a third seed layer 6 covering the temperature compensation layer. Figure 4 In the embodiment shown, the protective layer 7 covers at least a portion of the upper surface of the third seed layer 6 along the circumference of the temperature compensating layer 11 , and a portion of the upper surface of the third seed layer 6 is exposed through an opening defined by the inner edge of the protective layer 7 .

[0056] Figures 7-8 Schematic cross-sectional views of bulk acoustic wave resonators according to different embodiments of the present invention are shown as follows. Figure 7 and Figure 8 As shown, the third seed layer 6 may not be provided on the temperature compensating layer 11. In this case, the protective layer 7 covers at least a portion of the upper surface of the temperature compensating layer 11 along the circumference of the temperature compensating layer 11, and a portion of the upper surface of the temperature compensating layer is exposed through the opening defined by the inner edge of the protective layer 7.

[0057] exist Figure 7 In the structure shown, when manufactured, Figure 4 The difference in the manufacturing process of the structure shown is that after forming the temperature compensation layer 11, the third seed layer 6 is not deposited. After depositing the protective layer material, the protective layer 7 or the CP ring structure is directly formed by the liftoff process to protect the temperature compensation layer 11 from being released in subsequent steps. Figure 7 In the structure shown, there is no etching of the protective material layer and no over-etching of the exposed portion of the temperature compensation layer 11.Figure 7 The upper surface of the exposed portion of the temperature compensation layer 11 is a flat upper surface.

[0058] In the structure shown in Figure 8 In the structure shown in Figure 7 The difference between the manufacturing process of the structure shown in

[0059] As shown in Figure 4 and 7 -8, the protective layer 7 covers at least a portion of the electrode connection end and at least a portion of the non-electrode connection end of the bottom electrode 4. As can be understood, the protective layer 7 can cover at least a portion of the electrode connection end or at least a portion of the non-electrode connection end of the bottom electrode 4.

[0060] In one embodiment, referring to the right part in Figure 4 and 7 -8, at the non-electrode connection end of the bottom electrode, the protective layer 7 covers the bottom electrode 4 and the surface where the outer edge of the protective layer 7 is located is flush with the surface of the non-electrode connection end of the bottom electrode.

[0061] As mentioned above, the opening formed by the protective layer or CP ring structure can be closed or not closed. The specific description is made below with reference to Figures 9-11 . Figures 9-11 Exemplary top view schematic diagrams of bulk acoustic wave resonators according to different embodiments of the present application are shown.

[0062] In Figure 9 , the protective layer 7 or CP ring structure is only provided along the entire circumference of the non-electrode connection end of the top electrode, and is not provided at the electrode connection end of the top electrode. As can be understood, the protective layer 7 or CP ring structure can also be provided only along a part of the circumference of the non-electrode connection end of the top electrode.

[0063] In Figure 10 , the protective layer 7 or CP ring structure is provided at the electrode connection end of the top electrode in addition to being provided along the entire circumference of the non-electrode connection end of the top electrode.

[0064] In Figure 11 , the protective layer 7 or CP ring structure is provided at the electrode connection end of the top electrode in addition to being provided along the entire circumference of the non-electrode connection end of the top electrode.

[0065] Figure 6 An exemplary diagram showing the relationship between the width of the protective layer on the upper surface of the temperature compensation layer and the performance of the resonator is shown. It can be seen that the width Wl of the protective layer 7 on the upper surface of the temperature compensation layer has a great influence on the performance of the resonator. As shown in Figure 4 , when Wl is 0 or 2 μm, the parallel resonance impedance Rp of the resonator is relatively large, being 550 ohms, while when Wl is 7 μm, the parallel resonance impedance Rp of the resonator is relatively small, being 450 ohms. Figure 6

[0066] Correspondingly, in the exemplary embodiment of the present application, at the non-electrode connecting end of the top electrode 9, the inner edge of the protective layer 7 is on the inner side of the non-electrode connecting end of the top electrode 9 in the horizontal direction and the distance Wl therebetween is less than 7 μm, and in a further embodiment, the distance Wl therebetween is not less than 0 and less than 3 μm.

[0067] It should be noted that in one embodiment of the present application, the size of the CP ring or protective layer at the electrode connecting end of the resonator is not required. In another embodiment of the present application, the size limitation of the CP ring or protective layer at the electrode connecting end of the resonator can be consistent with that at the non-electrode connecting end, which is within the protection scope of the present application and will not be described here again.

[0068] The manufacturing process of the resonator shown in Figures 12A-12F will be described exemplarily below. Figure 4 The manufacturing process of the resonator shown in Figures 12A-12F will be described exemplarily below. Figure 4 The manufacturing process of the resonator shown in will be described exemplarily below.

[0069] Step 1: As shown in Figure 12A , a substrate 1 is provided, a cavity is formed on the substrate 1 by etching, a sacrificial material is deposited on the substrate 1 to fill the cavity, and then the surface of the sacrificial material layer in the cavity is made flush with the upper surface of the substrate 1 by a CMP process, for example. As mentioned later, the sacrificial material layer is released to form an acoustic mirror cavity 2.

[0070] Step 2: A first seed film layer and a conductive film layer are sequentially deposited on the structure shown in Figure 12A , and the two film layers are patterned by an etching process to form a first seed layer 3 and a bottom electrode 4, as shown in Figure 12B .

[0071] Step 3: As shown in Figure 12BA second seed material layer, which can be aluminum nitride, is deposited on the structure. Next, a conformal material layer, which is, for example, silicon dioxide, is deposited on the second seed material layer. Then, the conformal material layer is patterned to form the conformal layer 11, at which time the second seed layer 5 serves as an etch stop layer to protect the bottom electrode 4. Thereafter, the second seed material layer is etched to form the second seed layer 5. Thereafter, a third seed material layer, which can be aluminum nitride, is deposited and etched to pattern the third seed layer 6. The third seed layer 6 serves as a barrier layer to protect the conformal layer 11 when the conformal layer 11 is etched in a subsequent step to form the CP ring or the protection layer. In the case where seed layers are provided on both sides of the silicon dioxide conformal layer, the adhesion between the film layers is increased, and the film layer structure is more stable.

[0072] Step 4: As shown in FIG. 4, a protection material layer is deposited on the structure shown in FIG. 3, and then the protection material layer is etched to form the protection layer 7. In FIG. 4, it can be seen that the inner side of the protection layer 7 defines an opening. Figure 12D Figure 12C In this step, in the predetermined region (for example, the non-electrode connecting end of the top electrode), the protection layer 7 covers the upper surface of the conformal layer structure along at least a portion of the circumferential direction of the conformal layer structure, and a portion of the upper surface of the conformal layer structure is exposed via the opening defined by the inner edge of the protection layer. In addition, in this step, in the predetermined region (for example, the non-electrode connecting end of the top electrode), the position of the inner edge of the protection layer 7 needs to be set so that it is flush with or inside the non-electrode connecting end of the top electrode prepared in a subsequent step in the horizontal direction. Figure 12D

[0073] Step 5: As shown in FIG. 5, a piezoelectric layer 8 is deposited on the structure shown in FIG. 4. Figure 12E Figure 12D

[0074] Step 6: As shown in FIG. 6, a top electrode 9 and a process layer 10 are prepared on the structure shown in FIG. 5, thereby forming the structure shown in FIG. 1. Figure 12F Figure 12E Figure 4 In the present application, the CP ring or the protection layer 7 is mainly to prevent the conformal layer 11 from being released or etched by an etchant such as an HF solution.

[0075] In an embodiment of the present application, the outer side of the CP ring or the protection layer 7 is outside the boundary of the acoustic mirror cavity in the horizontal direction. In another embodiment of the present application, the outer side of the CP ring or the protection layer 7 can also be inside the boundary of the acoustic mirror cavity in the horizontal direction. Alternatively, the outer side of the CP ring or the protection layer 7 can also be flush with the non-electrode connecting end of the top electrode in the horizontal direction. These are all within the protection scope of the present application.

[0076]

[0077] ​​​​​​​The structure of the present application can also be applied to narrow-band product requirements, and can meet performance requirements under the premise of ensuring the electromechanical coupling coefficient.

[0078] For a resonator without a temperature compensation protective layer (for example Figure 1 As shown, the electromechanical coupling coefficient changes with the release time, but the electromechanical coupling coefficient of the resonator with the protective layer structure according to the present application is stable and does not change with the release time.

[0079] For a resonator with the interlayer electrode 12 as a temperature compensation protective layer (for example Figure 3 As shown, the performance (parallel resonance impedance Rp of the resonator) of the resonator based on the structure of the present application is significantly improved, as shown in Figure 5 As can be seen from Figure 5 , under the same conditions, the parallel resonance impedance Rp of the resonator for the structure shown in Figure 3 with the CM protective layer (i.e. with the interlayer electrode 12) is 170 ohms, while the parallel resonance impedance Rp of the resonator for the structure based on the present application, for example as shown in Figure 4 , with the protective layer 7 is 550 ohms.

[0080] In one embodiment of the present application, the electromechanical coupling coefficient of the bulk acoustic wave resonator using the protective layer structure of the present application is not greater than 3%.

[0081] It should be noted that in the present application, each numerical range, in addition to explicitly indicating that it does not include end values, can also be a median value of each numerical range, which is within the protection scope of the present application.

[0082] In the present application, up and down are relative to the bottom surface of the substrate of the resonator, and for a component, the side close to the bottom surface is the lower side, and the side away from the bottom surface is the upper side.

[0083] In the present application, inner and outer are relative to the center of the effective area of the resonator in the lateral direction or the radial direction, and one side or one end of a component close to the center is the inner side or the inner end, and the side or the end of the component away from the center is the outer side or the outer end. For a reference position, the inner side of the position means between the position and the center in the lateral direction or the radial direction, and the outer side of the position means farther away from the center than the position in the lateral direction or the radial direction.

[0084] As can be understood by those skilled in the art, the bulk acoustic wave resonator according to the present application can be used to form a filter or other semiconductor device.

[0085] Based on the above, the present application proposes the following technical solutions:

[0086] 1. A bulk acoustic wave resonator, comprising:

[0087] a substrate;

[0088] an acoustic mirror;

[0089] a bottom electrode;

[0090] a top electrode;

[0091] a piezoelectric layer disposed between the bottom electrode and the top electrode;

[0092] a temperature compensating layer structure disposed between the bottom electrode and the piezoelectric layer, the temperature compensating layer structure including a temperature compensating layer,

[0093] wherein:

[0094] the resonator further includes a protective layer;

[0095] at a non-electrode-connection end of the top electrode, the protective layer covers an upper surface of the temperature compensating layer structure along at least a portion of a circumference of the temperature compensating layer structure, a portion of the upper surface of the temperature compensating layer structure being exposed via an opening defined by an inner edge of the protective layer, the opening being at least partially within an active area of the resonator; and

[0096] at the non-electrode-connection end of the top electrode, the inner edge of the protective layer is flush with or inward of the non-electrode-connection end of the top electrode in a horizontal direction.

[0097] 2. The resonator according to 1, wherein:

[0098] the protective layer covers an upper surface of the temperature compensating layer along at least a portion of a circumference of the temperature compensating layer, a portion of the upper surface of the temperature compensating layer being exposed via an opening defined by an inner edge of the protective layer.

[0099] 3. The resonator according to 2, wherein:

[0100] the upper surface of the temperature compensating layer is a flat upper surface.

[0101] 4. The resonator according to 2, wherein:

[0102] the portion of the upper surface of the temperature compensating layer exposed via the opening is recessed relative to other portions of the upper surface of the temperature compensating layer.

[0103] 5. The resonator according to 1, wherein:

[0104] the temperature compensating layer structure includes the temperature compensating layer and a seed layer overlying the temperature compensating layer on an upper side thereof;

[0105] The protective layer covers at least a part of the upper surface of the seed layer along at least a part of the circumference of the temperature compensating layer structure, and a part of the upper surface of the seed layer is exposed through an opening defined by an inner edge of the protective layer.

[0106] 6. The resonator according to claim 1, wherein:

[0107] The protective layer covers at least a part of the electrode connection end of the bottom electrode and / or at least a part of the non-electrode connection end.

[0108] 7. The resonator according to claim 6, wherein:

[0109] In the non-electrode connection end of the bottom electrode, the protective layer covers the bottom electrode and a surface on which an outer edge of the protective layer is located is flush with a surface of the non-electrode connection end of the bottom electrode.

[0110] 8. The resonator according to claim 1, wherein:

[0111] An inner edge of the protective layer is a slope, an included angle between the slope and an upper surface of the temperature compensating layer structure covered by the protective layer is an acute angle, and based on the slope, a thickness of the protective layer gradually increases from the inside to the outside at the inner edge of the protective layer.

[0112] 9. The resonator according to claim 8, wherein:

[0113] The included angle is 90%-110% of an included angle of an end portion of the non-electrode connection end of the bottom electrode.

[0114] 10. The resonator according to claim 1, wherein:

[0115] In the non-electrode connection end of the top electrode, an inner edge of the protective layer is located inside the non-electrode connection end of the top electrode in a horizontal direction and a distance between them is less than 7 μm.

[0116] 11. The resonator according to claim 10, wherein:

[0117] In the non-electrode connection end of the top electrode, an inner edge of the protective layer is located inside the non-electrode connection end of the top electrode in a horizontal direction and a distance between them is less than 3 μm.

[0118] 12. The resonator according to claim 1, wherein:

[0119] The protective layer is a metal protective layer.

[0120] 13. The resonator according to claim 6, wherein:

[0121] The protective layer is a metal protective layer; and

[0122] The protective layer is electrically connected to the bottom electrode.

[0123] 14. The resonator according to any one of 1 to 12, wherein:

[0124] The protective layer is provided at least along the entire non-electrode-connection end of the top electrode.

[0125] 15. The resonator according to 14, wherein:

[0126] The protective layer is provided only along the non-electrode-connection end of the top electrode.

[0127] 16. The resonator according to 14, wherein:

[0128] The protective layer is provided along the entire non-electrode-connection end of the top electrode and a part of the electrode-connection end of the top electrode.

[0129] 17. The resonator according to 14, wherein:

[0130] The protective layer is a ring-shaped protective layer provided along the entire non-electrode-connection end of the top electrode and the entire electrode-connection end of the top electrode.

[0131] 18. The resonator according to 1, wherein:

[0132] The electromechanical coupling coefficient of the resonator is not more than 3%.

[0133] 19. A method of manufacturing a bulk acoustic wave resonator, the resonator including a substrate, an acoustic mirror, a bottom electrode, a top electrode, a piezoelectric layer provided between the bottom electrode and the top electrode, a temperature compensating layer structure including a temperature compensating layer, the temperature compensating layer structure being provided between the bottom electrode and the piezoelectric layer,

[0134] The method includes the steps of:

[0135] forming the temperature compensating layer structure on the bottom electrode;

[0136] after forming the temperature compensating layer structure, providing a protective layer such that:

[0137] at the non-electrode-connection end of the top electrode, the protective layer covers an upper surface of the temperature compensating layer structure along at least a part of a circumferential direction of the temperature compensating layer structure, a part of the upper surface of the temperature compensating layer structure being exposed via an opening defined by an inner edge of the protective layer; and at the non-electrode-connection end of the top electrode, the inner edge of the protective layer is flush with or inside the non-electrode-connection end of the top electrode in a horizontal direction.

[0138] 20. The method according to 19, wherein:

[0139] In the step of setting the protective layer, the protective layer is set only along the non-electrode connecting end of the top electrode; or, the protective layer is set along the entire non-electrode connecting end of the top electrode and part of the electrode connecting end of the top electrode; or, the protective layer is set along the entire non-electrode connecting end of the top electrode and the entire electrode connecting end of the top electrode.

[0140] 21. The method of 19, wherein:

[0141] The step of setting the protective layer comprises: setting a protective material layer covering the entire upper surface of the temperature compensation layer structure; and removing a part of the protective material layer at the upper surface of the temperature compensation layer structure to form the protective layer, the part of the protective material layer at the upper surface of the temperature compensation layer structure being at least partially within the effective area of the resonator.

[0142] 22. The method of 21, wherein:

[0143] The part of the protective material layer at the upper surface of the temperature compensation layer structure is removed by an etching process; or

[0144] The part of the protective material layer at the upper surface of the temperature compensation layer structure is removed by a stripping process.

[0145] 23. The method of 21, wherein:

[0146] In the step of removing the part of the protective material layer at the upper surface of the temperature compensation layer structure, the inner edge of the protective layer finally formed is on the inner side of the non-electrode connecting end of the top electrode in the horizontal direction, and the distance between the inner edge of the protective layer and the non-electrode connecting end of the top electrode is less than 7 μm.

[0147] 24. The method of any one of 19-23, wherein:

[0148] The protective layer is a metal protective layer; and

[0149] The protective layer is electrically connected to the bottom electrode.

[0150] 25. A filter comprising the bulk acoustic wave resonator of any one of 1-18.

[0151] 26. An electronic device comprising the filter of 25, or the bulk acoustic wave resonator of any one of 1-18.

[0152] The electronic device herein includes, but is not limited to, intermediate products such as radio frequency front ends, filter amplification modules, and terminal products such as mobile phones, WIFI, and drones.

[0153] While embodiments of the application have been shown and described, it is to be understood that the embodiments described are merely exemplary of the principles and application of the present application. Numerous modifications and adaptations will occur to those skilled in the art without departing from the spirit and scope of the present application.

Claims

1. A bulk acoustic wave resonator, comprising: substrate; Acoustic mirror; bottom electrode; Top electrode; a piezoelectric layer disposed between the bottom electrode and the top electrode; The temperature compensation layer structure is arranged between the bottom electrode and the piezoelectric layer. The temperature compensation layer structure includes a temperature compensation layer, in: The resonator further includes a protective layer; At the non-electrode connection end of the top electrode, the protective layer covers at least a portion of the upper surface of the temperature compensating layer structure along the circumference of the temperature compensating layer structure, a portion of the upper surface of the temperature compensating layer structure is exposed through an opening defined by an inner edge of the protective layer, and the opening is at least partially within the effective area of ​​the resonator; and At the non-electrode connection end of the top electrode, the inner edge of the protection layer is located inside the non-electrode connection end of the top electrode in the horizontal direction.

2. The resonator according to claim 1, wherein: The protective layer covers at least a portion of the upper surface of the thermal compensating layer along the circumference of the thermal compensating layer, and a portion of the upper surface of the thermal compensating layer is exposed through an opening defined by an inner edge of the protective layer.

3. The resonator according to claim 2, wherein: The upper surface of the temperature compensation layer is a flat upper surface.

4. The resonator according to claim 2, wherein: A portion of the upper surface of the temperature compensating layer exposed through the opening is recessed relative to other portions of the upper surface of the temperature compensating layer.

5. The resonator according to claim 1, wherein: The temperature compensating layer structure includes a temperature compensating layer and a seed layer covering the temperature compensating layer on the upper side of the temperature compensating layer; The protective layer covers at least a portion of the upper surface of the seed layer along the circumference of the temperature compensating layer structure, and a portion of the upper surface of the seed layer is exposed through an opening defined by an inner edge of the protective layer.

6. The resonator according to claim 1, wherein: The protection layer covers at least a portion of the electrode connection end and / or at least a portion of the non-electrode connection end of the bottom electrode.

7. The resonator according to claim 6, wherein: At the non-electrode connection end of the bottom electrode, the protective layer covers the bottom electrode, and the surface where the outer edge of the protective layer is located is flush with the non-electrode connection end surface of the bottom electrode.

8. The resonator of claim 1 , wherein: The inner edge of the protective layer is a slope, and the angle between the slope and the upper surface of the temperature compensation layer structure covered by the protective layer is an acute angle. Based on the slope, at the inner edge of the protective layer, the thickness of the protective layer gradually increases from the inside to the outside.

9. The resonator of claim 8, wherein: The degree of the included angle is 90%-110% of the degree of the included angle of the end portion of the non-electrode connection end of the bottom electrode.

10. The resonator of claim 1 , wherein: At the non-electrode connection end of the top electrode, the inner edge of the protective layer is located inside the non-electrode connection end of the top electrode in the horizontal direction and the distance between the two is less than 7 μm.

11. The resonator of claim 10, wherein: At the non-electrode connection end of the top electrode, the inner edge of the protective layer is located inside the non-electrode connection end of the top electrode in the horizontal direction and the distance between the two is less than 3 μm.

12. The resonator of claim 1 , wherein: The protective layer is a metal protective layer.

13. The resonator of claim 6, wherein: The protective layer is a metal protective layer; and The protection layer is electrically connected to the bottom electrode.

14. The resonator according to any one of claims 1 to 12, wherein: The protective layer is provided at least along the entire non-electrode connection end of the top electrode.

15. The resonator of claim 14, wherein: The protection layer is only provided along the non-electrode connection end of the top electrode.

16. The resonator of claim 14, wherein: The protection layer is arranged along the entire non-electrode connection end of the top electrode and a portion of the electrode connection end of the top electrode.

17. The resonator of claim 14, wherein: The protective layer is an annular protective layer provided along the entire non-electrode connection end of the top electrode and the entire electrode connection end of the top electrode.

18. The resonator of claim 1 , wherein: The electromechanical coupling coefficient of the resonator is no more than 3%.

19. A method for manufacturing a bulk acoustic wave resonator, the resonator comprising a substrate, an acoustic mirror, a bottom electrode, a top electrode, a piezoelectric layer disposed between the bottom electrode and the top electrode, and a temperature compensation layer structure comprising a temperature compensation layer, the temperature compensation layer structure being disposed between the bottom electrode and the piezoelectric layer. The method comprises the steps of: forming a temperature compensating layer structure on the bottom electrode, and disposing a seed layer between the bottom electrode and the temperature compensating layer structure; After forming the temperature compensation layer structure, a protective layer is set so that: At the non-electrode connection end of the top electrode, the protective layer covers at least a portion of the upper surface of the temperature compensating layer structure along the circumference of the temperature compensating layer structure, and a portion of the upper surface of the temperature compensating layer structure is exposed through an opening defined by the inner edge of the protective layer; and at the non-electrode connection end of the top electrode, the inner edge of the protective layer is located on the inner side of the non-electrode connection end of the top electrode in the horizontal direction.

20. The method of claim 19, wherein: In the step of setting the protective layer, the protective layer is set only along the non-electrode connecting end of the top electrode; or, along the entire non-electrode connecting end of the top electrode and part of the electrode connecting end of the top electrode; or, along the entire non-electrode connecting end of the top electrode and the entire electrode connecting end of the top electrode.

21. The method of claim 19, wherein: The step of providing a protective layer includes: providing a protective material layer covering the entire upper surface of the temperature compensating layer structure; removing a portion of the protective material layer located on the upper surface of the temperature compensating layer structure to form the protective layer, wherein the portion of the upper surface of the temperature compensating layer structure is at least partially located in the effective area of ​​the resonator.

22. The method of claim 21, wherein: removing a portion of the protective material layer on the upper surface of the temperature compensation layer structure by an etching process; or A portion of the protective material layer located on the upper surface of the temperature compensation layer structure is removed by using a stripping process.

23. The method of claim 21, wherein: In the step of "removing a portion of the protective material layer on the upper surface of the temperature compensation layer structure", the inner edge of the protective layer finally formed is located on the inner side of the non-electrode connection end of the top electrode in the horizontal direction and the distance between the two is less than 7μm.

24. The method according to any one of claims 19 to 23, wherein: The protective layer is a metal protective layer; and The protection layer is electrically connected to the bottom electrode.

25. A filter comprising the bulk acoustic wave resonator according to any one of claims 1 to 18.

26. An electronic device comprising the filter according to claim 25 or the bulk acoustic wave resonator according to any one of claims 1 to 18.

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