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

Abstract

The present invention relates to a bulk acoustic wave resonator, comprising: a substrate; an acoustic mirror; a bottom electrode; a top electrode; and a piezoelectric layer disposed between the bottom and top electrodes, wherein an acoustic impedance structure is disposed between the piezoelectric layer and the substrate; the acoustic impedance structure comprises a first acoustic impedance layer and a second acoustic impedance layer disposed adjacent to each other in a lateral direction, the first acoustic impedance layer and the second acoustic impedance layer having different acoustic impedances; the acoustic mirror is located between the first acoustic impedance layers in the lateral direction of the resonator; and the resonator further comprises a temperature compensation layer. The present invention 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] Furthermore, BAW resonators typically exhibit a negative frequency temperature drift coefficient of approximately -30ppm / °C. This is because the piezoelectric and electrode materials of BAW resonators exhibit negative frequency temperature drift coefficients, meaning that the stiffness of these materials decreases with increasing temperature. This decrease in stiffness also reduces the speed of sound. 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 piezoelectric layer), as the speed of sound decreases, the frequency decreases. Therefore, BAW resonators experience frequency drift as temperature increases. Summary of the Invention

[0005] The present invention is proposed to alleviate or solve at least one aspect of the above-mentioned problems in the prior art and to improve the Q value of a BAW resonator and the temperature stability of the BAW resonator.

[0006] According to one aspect of an embodiment of the present invention, a bulk acoustic wave resonator is provided, comprising:

[0007] substrate;

[0008] Acoustic mirror;

[0009] bottom electrode;

[0010] a top electrode; and

[0011] A piezoelectric layer is provided between the bottom electrode and the top electrode,

[0012] in:

[0013] An acoustic impedance structure is provided between the piezoelectric layer and the substrate;

[0014] The acoustic impedance structure includes a first acoustic impedance layer and a second acoustic impedance layer arranged adjacent to each other in a transverse direction, the first acoustic impedance layer and the second acoustic impedance layer having different acoustic impedances, and the acoustic mirror is located between the first acoustic impedance layers in the transverse direction of the resonator;

[0015] The resonator further includes a temperature compensation layer.

[0016] An embodiment of the present invention further relates to a filter, comprising the above-mentioned bulk acoustic wave resonator.

[0017] An embodiment of the present invention also relates to an electronic device, comprising the above-mentioned filter or the above-mentioned resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The following description and accompanying drawings may better help understand these and other features and advantages of various embodiments disclosed herein, wherein like reference numerals denote like components throughout the drawings, wherein:

[0019] Figure 1 and 2 Schematic cross-sectional views of bulk acoustic wave resonators according to different exemplary embodiments of the present invention, respectively, wherein the cross-section passes through an electrode lead-out portion of a bottom electrode, wherein a temperature compensation layer is at least partially disposed between the bottom electrode and the piezoelectric layer;

[0020] Figure 3 and 4 Schematic cross-sectional views of a bulk acoustic wave resonator according to different exemplary embodiments of the present invention, respectively, wherein the cross-section passes through an electrode lead-out portion of a bottom electrode, wherein a temperature compensation layer is at least partially disposed on a lower surface of the bottom electrode;

[0021] Figure 5-9 , 12, 15-18, 20 are schematic cross-sectional views of a bulk acoustic wave resonator according to different exemplary embodiments of the present invention, the cross-section passing through the electrode lead-out portion of the bottom electrode, wherein the temperature compensation layer is at least partially disposed in the bottom electrode;

[0022] Figure 10 and 11 According to different embodiments of the present invention Figure 9A schematic top view of the relationship between the bottom electrode and the temperature compensation layer, wherein the structure of the connecting portion that electrically connects the upper and lower parts of the bottom electrode to each other is shown;

[0023] Figure 13 and 14 According to different embodiments of the present invention Figure 12 A schematic top view of the relationship between the bottom electrode and the temperature compensation layer, wherein the structure of the connecting portion that electrically connects the upper and lower parts of the bottom electrode to each other is shown;

[0024] Figure 19 According to an embodiment of the present invention Figure 18 A schematic top view of the relationship between the bottom electrode and the temperature compensation layer;

[0025] Figure 21 According to an embodiment of the present invention Figure 20 A schematic top view of the relationship between the bottom electrode and the temperature compensation layer;

[0026] Figure 22-25 They are schematic cross-sectional views of a bulk acoustic wave resonator according to different embodiments of the present invention, respectively. The cross-section passes through the electrode lead-out portion of the bottom electrode, wherein the temperature compensation layer is at least partially disposed in the top electrode;

[0027] Figure 26 1 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an embodiment of the present invention, wherein the cross-section passes through the electrode lead-out portion of the bottom electrode, wherein temperature compensation layers are provided in both the top electrode and the bottom electrode. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is further specifically described below through examples and in conjunction with the accompanying drawings. In the specification, the same or similar drawing numbers indicate the same or similar parts. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be understood as a limitation of the present invention. Some embodiments of the invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention.

[0029] First, the reference numerals in the accompanying drawings of the present invention are explained as follows:

[0030] 101: Substrate, optional materials include single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0031] 103: Acoustic mirror, which can be a cavity, a Bragg reflector layer or other equivalent forms. In the embodiment shown in the present invention, a cavity is provided on the upper surface of the substrate. In an optional embodiment, the cavity can also be located inside the substrate.

[0032] 105: Acoustic impedance layer 1 or the first acoustic impedance layer, the material of which may be aluminum nitride, silicon dioxide, silicon nitride, polysilicon, or amorphous silicon.

[0033] 107: Acoustic impedance layer 2 or the second acoustic impedance layer, which also serves as a sacrificial layer. The second acoustic impedance layer can be made of silicon dioxide, doped silicon dioxide, polycrystalline silicon, amorphous silicon, etc., but the material of the second acoustic impedance layer is different from that of the first acoustic impedance layer, and the etchant for the second acoustic impedance layer is not easily etched or does not etch the material of the first acoustic impedance layer.

[0034] 109: Bottom electrode, optional materials: 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 other similar metals.

[0035] 111: The piezoelectric layer can be a single crystal piezoelectric material, such as 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), such as polycrystalline aluminum nitride, zinc oxide, PZT, etc., and can also be a rare earth element doped with a certain atomic ratio of the above materials. The miscellaneous material may be, for example, 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.

[0036] 113: Electrode lead-out portion, which can be manufactured simultaneously with the top electrode. The material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof.

[0037] 115: Top electrode, which can be made of the same material as the bottom electrode. The material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium, or a composite or alloy of the above metals. The top and bottom electrodes are generally made of the same material, but can also be different.

[0038] 117: Temperature compensation layer. Temperature compensation layer 117 is disposed on the underside of the piezoelectric layer. The material of temperature compensation layer 117 is a material with a frequency temperature coefficient opposite to that of the piezoelectric layer. Materials such as polysilicon, borophosphate glass (BSG), silicon dioxide (SiO2), fluorine-doped silicon dioxide, chromium (Cr), or tellurium oxide (TeO(x)) can be used. For example, the stiffness of materials with positive frequency temperature drift coefficients, such as SiO2, increases with increasing temperature. Therefore, by adding a layer of material with positive frequency temperature drift coefficients, such as SiO2 (i.e., a temperature compensation layer), the decrease in sound velocity caused by the decrease in stiffness of an ordinary resonator (without a temperature compensation layer) with increasing temperature can be compensated or reduced, thereby reducing the negative frequency drift caused by increasing temperature. Furthermore, by setting an appropriate thickness of the temperature compensation layer, zero temperature drift or a frequency temperature drift coefficient within the range of ±5ppm / °C can be achieved. In the drawings shown in the present invention, the electrode connection end of the bottom electrode is located on the left side of the figure. For the convenience of expression, in the present invention, the left end of the temperature compensating layer 117 in the horizontal direction or the lateral direction, that is, the end close to the electrode lead-out portion 113 is defined as the first end; the right end of the temperature compensating layer 117 in the horizontal direction or the lateral direction, that is, the end away from the electrode lead-out portion 113 (or the end close to the non-connected edge of the bottom electrode) is defined as the second end.

[0039] 119: Temperature compensating layer. Temperature compensating layer 119 is disposed on the upper side of the piezoelectric layer. The material range of temperature compensating layer 119 is the same as that of temperature compensating layer 117. In the same resonator, temperature compensating layer 119 can be made of the same material as or different from that of temperature compensating layer 117. In the present invention, the left end of temperature compensating layer 119 in the horizontal or lateral direction, i.e., the end closer to electrode lead portion 113, is defined as the first end; the right end of temperature compensating layer 119 in the horizontal or lateral direction, i.e., the end farther from electrode lead portion 113, is defined as the second end.

[0040] Figure 1 and 2 1 and 2 are schematic cross-sectional views of a bulk acoustic wave resonator according to different exemplary embodiments of the present invention, respectively, where the cross-section passes through an electrode lead-out portion of a bottom electrode.

[0041] like Figure 1-2 As shown, an acoustic impedance structure is provided between the piezoelectric layer 111 and the substrate 101, and the acoustic mirror 103 is located between the acoustic impedance structure in the lateral direction of the resonator. The acoustic impedance structure includes a first acoustic impedance layer 105 and a second acoustic impedance layer 107 arranged adjacent to each other in the lateral direction. More specifically, the acoustic mirror 103 is located between the first acoustic impedance layer 105 in the lateral direction of the resonator.

[0042] In the present invention, the acoustic impedances of the first acoustic impedance layer and the second acoustic impedance layer are different, so as to form an impedance mismatch, form continuous reflection of the sound waves, and form a reflection structure for the transverse sound waves, thereby preventing the leakage of transverse sound waves, which is beneficial to locking the energy in the resonator, thereby improving the Q value.

[0043] In the present invention, single crystal piezoelectric material is used, which can reduce piezoelectric loss, thereby obtaining a higher resonator Q value, and at the same time can improve the electromechanical coupling coefficient and power capacity.

[0044] In a further embodiment, the widths of the portions of the first acoustic impedance layer 105 and the second acoustic impedance layer 107 in contact with the piezoelectric layer 111 are mλ1 / 4 and nλ2 / 4, respectively, where m and n are both odd numbers, such as 1, 3, 5, 7, etc., and λ1 and λ2 are the wavelengths of the acoustic waves propagating laterally at the resonant frequency of the first acoustic impedance layer and the second acoustic impedance layer, respectively. The resonant frequency is a frequency within the resonant range of the resonator, which can be the series resonant frequency or the parallel resonant frequency of the resonator, or a frequency between the series and parallel resonant frequencies, or a frequency slightly lower than the series resonant frequency or slightly higher than the parallel resonant frequency. In the accompanying drawings, the width of the first acoustic impedance layer 105 is represented by A, and the width of the second acoustic impedance layer 107 is represented by B. Selecting the above widths is conducive to forming an effective acoustic impedance mismatch, preventing lateral sound wave leakage, and further improving the Q value of the resonator. m and n can be the same or different, and are both within the scope of protection of the present invention.

[0045] The materials forming the first acoustic impedance layer 105 include aluminum nitride, silicon dioxide, silicon nitride, polycrystalline silicon, and amorphous silicon. The materials forming the second acoustic impedance layer 107 include silicon dioxide, doped silicon dioxide, polycrystalline silicon, and amorphous silicon. The materials of the first acoustic impedance layer 105 and the second acoustic impedance layer 107 are different. Alternatively, the material forming the first acoustic impedance layer 105 includes silicon dioxide, and the material forming the second acoustic impedance layer 107 includes polycrystalline silicon. Alternatively, the material forming the first acoustic impedance layer 105 includes silicon nitride or aluminum nitride, and the material forming the second acoustic impedance layer 107 includes silicon dioxide or doped silicon dioxide. In the present invention, to increase the degree of acoustic mismatch at the junction of the first acoustic impedance layer 105 and the second acoustic impedance layer 107, the difference in acoustic impedance between the two layers can be selected to be as large as possible.

[0046] During the manufacturing process of the resonator, the second acoustic impedance layer is also used as a sacrificial layer. Therefore, when releasing the sacrificial layer, a suitable release etchant needs to be selected so that the etchant only etches the first acoustic impedance material and does not etch or etches a very small amount of the second acoustic impedance material.

[0047] like Figure 1 As shown, the non-electrode connection end of the bottom electrode 109 ( Figure 1-2The end face of the bottom electrode 109 (right end) is separated from the first acoustic impedance layer 105 in the acoustic impedance structure in the lateral direction, so that the sound wave is also totally reflected at the lateral interface between the non-electrode connection end of the bottom electrode and the gap, thereby reducing the leakage of the sound wave. Based on the gap structure at the non-electrode connection end, the lateral sound wave leakage can be further prevented and the Q value of the resonator can be improved. On the other hand, the non-electrode connection end of the bottom electrode 109 ( Figure 1-2 The end surface of the top electrode (the right end in the figure) can also be covered by the first acoustic impedance layer 105. Although this will form a parasitic capacitance with the portion of the top electrode outside the cavity, thereby affecting the electromechanical coupling coefficient of the resonator, the contact between the electrode and the first acoustic impedance layer can better conduct the heat generated by the resonator to the substrate, thereby improving the power handling capacity. In the cross-section of the non-connected edges of the bottom and top electrodes (not shown), the non-connected end of the bottom electrode can be separated from the first acoustic impedance layer 105 to improve the Q value of the resonator, or it can be covered by the first acoustic impedance layer 105 to improve the power handling capacity of the resonator.

[0048] In an alternative embodiment, in a longitudinal section of the resonator through the electrode connection end of the bottom electrode 109 (eg Figure 1-2 In the cross-sectional view shown in FIG, the distance C between the end surface of the non-electrode connection end of the bottom electrode 109 and the acoustic impedance structure in the lateral direction is in the range of 0.5 μm to 10 μm. In addition to the end value, this distance can also be, for example, 5 μm, 7 μm, etc.

[0049] exist Figure 1-2 In the illustrated embodiment, the bottom electrode 109 is wrapped on one side of the electrode connection end by a continuous reflective layer or acoustic impedance structure formed by the first acoustic impedance layer 105 and the second acoustic impedance layer 107. More specifically, it is covered by the first acoustic impedance layer 105. On the one hand, this structure helps improve the mechanical stability of the resonator and more easily conducts the heat generated during operation of the resonator to the substrate through the electrode and the first acoustic impedance layer 105, thereby increasing the power capacity of the resonator. On the other hand, although energy will leak from the end surface of the bottom electrode into the first acoustic impedance layer 105, the presence of the reflective interface formed by the second acoustic impedance layer and the first acoustic impedance layer helps to lock as much energy as possible inside the resonator, thereby maintaining a high Q value of the resonator.

[0050] It should be clearly pointed out that the above reference Figure 1-2 The description of the acoustic impedance structure is also applicable to other embodiments of the present invention.

[0051] exist Figure 1-2 In the embodiment, the temperature compensation layer 117 is provided between the bottom electrode 109 and the piezoelectric layer 111 .

[0052] Figure 1-2 The three distances l1, l2 and l3 are shown in Figure 1, and are described as follows:

[0053] Definition: l1: The horizontal distance between the first end of the top electrode 115 and the first end of the temperature compensating layer 117. l1 can be greater than 0 or less than 0. When l1 is greater than 0, in an optional embodiment, its length can be set to 1μm-20μm. When l1 is less than 0, in an optional embodiment, its length can be set to 0-10μm. At this time, the first end of the temperature compensating layer falls within the effective area, forming an impedance mismatch interface there. Therefore, the length selection of l1 will also affect the resonator Q value. l2: The horizontal distance between the electrode connection end 113 and the first end of the temperature compensating layer 117. l2 is at least greater than 0 to ensure that the electrical connection between the electrode lead end 113 and the bottom electrode 109 is not affected by the temperature compensating layer. Optionally, it can be set to 1μm-20μm. l3: The horizontal distance between the second end of the temperature compensating layer 117 and the second end of the bottom electrode 109. When l3 is a positive value, it means that the second end of the temperature compensation layer 117 does not extend out of the bottom electrode 109. At this time, the length range of l3 is 0-10 μm. Figure 1 As shown, the second end of the temperature compensation layer falls within the effective area, forming an impedance mismatch interface here. Therefore, the length selection of l3 will also affect the resonator Q value; and when l3 is a negative value, it means that the second end of the temperature compensation layer 117 extends out of the bottom electrode 109. At this time, l3 can be greater than 0 and can extend into the cavity, as shown in FIG. Figure 2 As shown, it can also be further extended to the first acoustic impedance layer outside the cavity, or further extended to the second acoustic impedance layer outside (similar to Figure 3 (Situation on the right side of the medium temperature compensation layer).

[0054] Whether the temperature compensating layer can extend to the outside of the edge of the bottom electrode and contact the acoustic mirror part is related to the material selection of the temperature compensating layer, the first acoustic impedance layer, and the second acoustic impedance layer. For example, when the temperature compensating layer and the second acoustic impedance layer (also used as the sacrificial layer of the acoustic mirror) are made of the same material (such as silicon dioxide), and the first acoustic impedance layer is made of silicon nitride or aluminum nitride, the temperature compensating layer cannot extend to the outside of the bottom electrode; and when the temperature compensating layer and the second acoustic impedance layer are made of different materials, and the temperature compensating layer is insensitive to the etchant of the second acoustic impedance layer, such as when the temperature compensating layer is made of silicon dioxide, the second acoustic impedance layer is made of polysilicon, and the first acoustic impedance layer is made of silicon dioxide, silicon nitride, or aluminum nitride, the temperature compensating layer can extend to the outside of the bottom electrode. In the following embodiments, whether the temperature compensating layer can extend to the outside of the bottom electrode, the material selection is consistent with the description here and will not be repeated.

[0055] Although not shown, Figure 1-2 In terms of the first end of the temperature compensation layer 117, in addition to being Figure 1-2In addition to extending to the outside of the non-electrode connection end of the top electrode 115 and overlapping with the first acoustic impedance layer 105, it can also be located on the inside of the non-electrode connection end of the top electrode 115 in the lateral direction (similar to Figure 16 The left end of the temperature compensation layer 117 is located between the non-electrode connection end of the top electrode 115 and the boundary of the first acoustic impedance layer 105 in the lateral direction (similar to Figure 17 These are all within the scope of protection of the present invention.

[0056] based on Figure 1-2 In this embodiment, a layer of material with a positive frequency temperature drift coefficient, namely, a temperature compensation layer 117, is provided between the piezoelectric layer and the bottom electrode. This prevents or reduces the frequency drift of the resonator and improves the temperature stability of the resonator. Typically, the temperature compensation layer is made of a dielectric material. In this case, a capacitor generated by the temperature compensation layer is connected in series with the original resonator, significantly reducing the electromechanical coupling coefficient of the resonator. Therefore, this structure is more suitable for narrowband filter applications.

[0057] Figure 3 and 4 They are schematic cross-sectional views of bulk acoustic wave resonators according to different exemplary embodiments of the present invention, respectively. The cross-section passes through the electrode lead-out portion of the bottom electrode, wherein the temperature compensation layer is at least partially disposed on the lower surface of the bottom electrode.

[0058] exist Figure 3 In the embodiment, the temperature compensation layer 117 is arranged outside the bottom electrode or on the lower surface of the bottom electrode, and Figure 3 As shown, the temperature compensation layer 117 covers the entire lower surface of the bottom electrode of the entire resonator and also covers Figure 3 The other lower surface of the piezoelectric layer except the bottom electrode.

[0059] exist Figure 4 In the embodiment, the temperature compensation layer 117 is arranged outside the bottom electrode or on the lower surface of the bottom electrode, and Figure 4 As shown, the temperature compensation layer 117 covers the entire lower surface of the bottom electrode of the entire resonator and also covers Figure 4 The lower surface of the piezoelectric layer except the bottom electrode. Figure 4 As shown, two distances l3 and l4 are shown, which are explained as follows:

[0060] l3 is still the distance between the second end of the temperature compensating layer 117 and the second end of the bottom electrode 109 in the horizontal direction or lateral direction, which is generally set to 0μm-10μm; l4 is the distance between the first end of the temperature compensating layer 117 and the first end of the bottom electrode 109 in the horizontal direction or lateral direction, which is generally set to 0μm-10μm.

[0061] Figure 3-4In the illustrated embodiment, during the corresponding processing, the temperature compensation layer is in direct contact with the material of the second acoustic impedance layer in the acoustic mirror. Therefore, a suitable temperature compensation layer material must be selected to make it insensitive to the etchant of the second acoustic impedance layer. For example, silicon dioxide is selected for the temperature compensation layer, polysilicon is selected for the second acoustic impedance layer, and silicon dioxide, silicon nitride, or aluminum nitride is selected for the first acoustic impedance layer.

[0062] Although not shown, when the temperature compensation layer 117 is provided on the lower surface of the bottom electrode 109, it may also cover only a portion of the lower surface of the bottom electrode. Figure 4 The values ​​l3 and l4 shown in the figure are negative. When the temperature compensation layer falls into the resonator's active area in the lateral direction, the distance from both ends of the temperature compensation layer to the edge of the active area must be within the range of 0-10 μm. Alternatively, the temperature compensation layer can extend from one end of the bottom electrode to cover the lower surface of the piezoelectric layer while not extending from the other end. All of these are within the scope of protection of the present invention.

[0063] based on Figure 3-4 In the embodiment, a positive frequency temperature drift coefficient material layer, namely the temperature compensation layer 117, is provided on the lower side of the bottom electrode (away from the piezoelectric layer), thereby preventing or reducing the frequency drift of the resonator and improving the temperature stability of the resonator. At this time, since the temperature compensation layer is outside the electrode, no corresponding capacitance is generated to affect the electromechanical coupling coefficient of the resonator. However, compared with the method based on Figure 1-2 In the embodiment, the temperature compensation layer is farther away from the piezoelectric layer. Therefore, the temperature compensation effect produced by the temperature compensation layer of the same thickness will be worse. In other words, a thicker temperature compensation layer is required to achieve the same temperature compensation effect. If the thickness of the temperature compensation layer is too large, the main vibration mode of the resonator will change, thereby affecting other electrical properties of the resonator (such as Q value or electromechanical coupling coefficient). Therefore, based on Figure 3-4 The embodiment can achieve better resonator performance with limited temperature compensation effect.

[0064] Figure 5-9 , 12, 15-18, 20 are schematic cross-sectional views of BAW resonators according to different exemplary embodiments of the present invention, the cross-sections passing through the electrode lead-out portion of the bottom electrode, wherein the temperature compensation layer is at least partially disposed in the bottom electrode. Figure 1-2 In the embodiment shown and the embodiments shown in 3-4, in this group of embodiments, the temperature compensation layer can be closer to the piezoelectric layer. At the same time, because the temperature compensation layer and the piezoelectric layer are separated by an electrode layer, the thickness of the temperature compensation layer and the longitudinal position of the temperature compensation layer in the bottom electrode can be flexibly set to achieve the desired temperature compensation effect without causing an excessive decrease in the electromechanical coupling coefficient of the resonator. Optionally, the thickness of the bottom electrode on the side close to the piezoelectric layer is less than the thickness of the bottom electrode on the side away from the piezoelectric layer.

[0065] It should be noted that the temperature compensation layer structure can be provided with only a single temperature compensation layer, or it can have other structures. For example, to ensure the feasibility or stability of processing, cut-off layers can be selectively provided above and below the temperature compensation layer. In this patent, a single temperature compensation layer is used as an example, but temperature compensation layers of other structures are also within the scope of protection of this invention.

[0066] like Figure 5 As shown, the temperature compensating layer 117 extends horizontally across the entire bottom electrode 109 and covers the rest of the bottom surface of the piezoelectric layer outside the bottom electrode. As will be appreciated by those skilled in the art, the temperature compensating layer may also cover only a portion of the bottom surface of the piezoelectric layer outside the bottom electrode.

[0067] exist Figure 5 In FIG, 121 is an opening provided on the temperature compensating layer 117, the purpose of which is to connect the bottom electrodes separated by the temperature compensating layer 117 so as to maintain the same potential. Figure 5 It can be seen that the opening 121 is arranged outside the effective area of ​​the resonator (in the present invention, the effective area of ​​the resonator refers to the overlapping area of ​​the top electrode, piezoelectric layer, bottom electrode and acoustic mirror of the resonator in the thickness direction of the resonator).

[0068] like Figure 5 As shown, the bottom electrode 109 is divided into two parts, the upper part and the lower part, by the temperature compensation layer 117, and the upper part is defined as 109a and the lower part as 109b; l5 is defined as the distance between the second end of the bottom electrode 109a and the second end of the bottom electrode 109b in the horizontal direction, l5 is greater than 0, and is generally set to 1μm-10μm. When l5 is less than 0, a stacked structure such as the bottom electrode lower part 109b, the temperature compensation layer, the piezoelectric layer, and the top electrode is formed from bottom to top outside the second end of the bottom electrode upper part 109a, so as to be similar to Figure 1-2 The embodiment shown in the figure will cause the electromechanical coupling coefficient of the resonator to decrease. l6 is defined as the size of the opening 121. To ensure sufficient electrical connection between the upper and lower portions of the bottom electrode, it is generally set within the range of 5 μm to 100 μm. However, the shape of the opening is not limited and can be rectangular, circular, or any other shape.

[0069] The opening 121 may also be arranged in an effective area, such as Figure 6 shown. Figure 6 and Figure 5 The difference lies in the placement of opening 121. In this case, two impedance mismatching interfaces are formed on either side of opening 121. Therefore, the choice of l6 affects the resonator Q value, which can be selected within the range of 2-10μm. The shape of opening 121 can be a ring surrounding the entire active area, a semi-ring surrounding only the non-connected edge of the bottom electrode, a localized strip, a hole, or any other arbitrary shape.

[0070] like Figure 7 As shown, the temperature compensation layer outside the bottom electrode 109 may only cover a portion of the lower surface of the piezoelectric layer except the bottom electrode. Figure 7 Wherein l3, l5 and l6 have the same definitions or meanings as before.

[0071] like Figure 8 As shown, the second end of the temperature compensation layer 117 can be disposed inside the bottom electrode 109 .

[0072] like Figure 9 As shown, in the case where the temperature compensating layer 117 extends across the entire bottom electrode in the horizontal direction, the opening 121 can also be set within the active area and outside the active area.

[0073] Figure 10 and 11 According to different embodiments of the present invention Figure 9 A schematic top view of the relationship between the bottom electrode and the temperature compensation layer, wherein the structure of the connecting portion or opening that electrically connects the upper and lower parts of the bottom electrode to each other is shown, Figure 9 Can be along Figure 10 Or the cross-sectional view taken along line AA in 11. The opening for connecting the bottom electrodes on the upper and lower sides of the temperature compensation layer can be a continuous ring structure, such as Figure 10 As shown, it can also be a ring array structure composed of multiple openings, such as Figure 11 shown.

[0074] In addition to providing a single opening or providing an annular opening (such as Figure 10 and 11 In addition to the above, the openings 121 may also be distributed in any shape on the portion of the temperature compensating layer 117 located within the bottom electrode 109 .

[0075] Figure 13 and 14 According to different embodiments of the present invention Figure 12 A schematic top view of the relationship between the bottom electrode and the temperature compensation layer, wherein the structure of the connecting portion or opening that electrically connects the upper and lower parts of the bottom electrode to each other is shown, Figure 12 It is along Figure 13 Or the cross-sectional view taken along line AA of 14. Figure 13 As shown, a plurality of concentrically arranged continuous open rings are provided in the temperature compensation layer 117, as shown in FIG. Figure 14 As shown, multiple annular array structures are concentrically arranged in the temperature compensation layer 117 .

[0076] exist Figure 15 In the embodiment, in addition to the temperature compensating layer 117 being provided in the bottom electrode 109 as shown in the figure, the temperature compensating layer 119 is also provided in the top electrode 115 as shown in the figure.

[0077] exist Figure 5-15 In the illustrated embodiment, the temperature compensating layer 117 is partially disposed within the bottom electrode 109, and the bottom electrodes above and below the temperature compensating layer are connected by an opening 121. However, the present invention is not limited thereto. The temperature compensating layer 117 may also be entirely disposed within the bottom electrode 109, and the upper portion of the temperature compensating layer 117 does not affect the connection or connectivity between the bottom electrodes above and below the temperature compensating layer 117. Figure 16-20 Such an example is given.

[0078] Figure 16 1 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an exemplary embodiment of the present invention, wherein the cross-section passes through the electrode lead-out portion of the bottom electrode, wherein the temperature compensation layer 117 is entirely disposed in the bottom electrode 109 .

[0079] exist Figure 16 In the figure, the temperature compensating layer 117 is only provided within the bottom electrode in terms of thickness and laterally within the active region of the resonator. L2 is defined as the horizontal distance between the first end of the temperature compensating layer 117 and the inner edge of the top electrode 115, typically set to 0μm-10μm. L3 is defined as the horizontal distance between the second end of the temperature compensating layer 117 and the non-electrode connection end of the bottom electrode 109, typically set to 0μm-10μm. Because the temperature compensating layer falls within the active region, an impedance mismatch interface is formed at the edge of the temperature compensating layer. Therefore, the distances between L2 and L3 further affect the resonator Q value.

[0080] Furthermore, the first end of the temperature compensation layer 117 can be arranged horizontally between the acoustic impedance layer 105 and the top electrode 115, as shown in FIG. Figure 17 As shown. Figure 17 In the embodiment, L4 is defined as the horizontal distance between the first end of the temperature compensation layer and the inner edge of the acoustic impedance layer 105, which is generally set to 0 μm-10 μm.

[0081] Furthermore, the first end of the temperature compensation layer 117 can also be arranged horizontally outside the acoustic mirror 103 without exceeding the bottom edge of the electrode lead portion 113, as shown in FIG. Figure 18 As shown. Figures 16 to 18 The warming effect of the warming layer can be further improved.

[0082] In such Figure 16-18 In the embodiment shown, the temperature compensation layer is completely wrapped by the bottom electrode, so the material selection is more flexible than in the previous embodiment. For example, the temperature compensation layer and the second acoustic impedance layer can be made of the same material, such as silicon dioxide.

[0083] Figure 19 According to an embodiment of the present invention Figure 18 Schematic top view of the relationship between the bottom electrode and the temperature compensation layer, Figure 18 for Figure 19 Cross-section along AA.

[0084] In order to eliminate Figure 16-18 The impedance mutation brought by the second end of the temperature compensation layer 117 can be extended to the end surface of the bottom electrode so that the second end of the temperature compensation layer 117 is flush with the end surface of the bottom electrode 109, as shown in FIG. Figure 20 At this point, during the processing, the temperature compensation layer is in direct contact with the material of the second acoustic impedance layer in the acoustic mirror. Therefore, a suitable temperature compensation layer material must be selected to make it insensitive to the etchant of the second acoustic impedance layer. For example, silicon dioxide is selected for the temperature compensation layer, polysilicon is selected for the second acoustic impedance layer, and silicon dioxide, silicon nitride, or aluminum nitride is selected for the first acoustic impedance layer.

[0085] Figure 21 According to an embodiment of the present invention Figure 20 Schematic top view of the relationship between the bottom electrode and the temperature compensation layer, Figure 20 for Figure 19 Cross-section along AA.

[0086] Figure 22-25 They are schematic cross-sectional views of a bulk acoustic wave resonator according to different embodiments of the present invention, respectively. The cross-section passes through the electrode lead-out portion of the bottom electrode, wherein the temperature compensation layer is at least partially disposed in the top electrode.

[0087] exist Figure 22 In the embodiment, the temperature compensation layer 119 is only provided in the top electrode 115 in terms of thickness and is located in the effective area of ​​the resonator in the lateral direction. Figure 22 In the figure, L2 is defined as the horizontal distance between the first end of the temperature compensating layer and the inner edge of the top electrode 115, which is generally set to 0 μm-10 μm; L3 is defined as the horizontal distance between the second end of the temperature compensating layer and the inner edge of the bottom electrode 109, which is generally set to 0 μm-10 μm. Figure 22 The technical effects of the structure shown and Figure 16 The technical effect of the structure in which the medium temperature compensation layer is only provided in the bottom electrode is the same.

[0088] In an optional embodiment, in order to improve the impedance mutation caused by the second end of the temperature compensating layer 119, the second end of the temperature compensating layer 119 can be extended to the outside of the bottom electrode 109, but not reaching the top of the first acoustic impedance layer 105, such as Figure 23 shown.

[0089] exist Figure 23 In the figure, L2 is defined as the horizontal distance between the first end of the temperature compensating layer and the inner edge of the top electrode 115, which is generally set to 0μm-10μm; L6 is the horizontal distance between the second end of the temperature compensating layer 119 and the acoustic impedance layer 105, which is generally set to 0μm-10μm.

[0090] In an optional embodiment, the second end of the temperature compensation layer 119 can be extended to the outside of the acoustic mirror 103, that is, above the first acoustic impedance layer 105, as shown in FIG. Figure 24 shown.

[0091] exist Figure 23 Or based on 24, to improve the first end of the temperature compensation layer 119 ( Figure 25 The impedance mutation caused by the left side of the temperature compensation layer 119 can be flush with the left side of the top electrode 115 to further improve the adverse effects of the impedance mutation, such as Figure 25 As shown. Further, in Figure 25 On the basis of , the left end of the temperature compensation layer can be extended to the surface of the piezoelectric layer outside the effective area of ​​the resonator.

[0092] As those skilled in the art will appreciate, when the temperature compensating layer 119 is disposed in the top electrode, an opening for connecting the upper and lower sides of the top electrode may be disposed in the temperature compensating layer 119 as in the temperature compensating layer 117 .

[0093] When a temperature compensating layer is set above the piezoelectric layer, the material of the temperature compensating layer can be freely selected only when the temperature compensating layer is completely wrapped by the top electrode. When the temperature compensating layer has a portion outside the top electrode, the temperature compensating layer will contact the etchant of the second acoustic impedance layer (sacrificial layer) during the processing. Therefore, a suitable temperature compensating layer material must be selected to make it insensitive to the etchant of the second acoustic impedance layer. For example, silicon dioxide is selected for the temperature compensating layer, polysilicon is selected for the second acoustic impedance layer, and silicon dioxide, silicon nitride, or aluminum nitride is selected for the first acoustic impedance layer.

[0094] Figure 26 1 is a schematic cross-sectional view of a bulk acoustic wave resonator according to an embodiment of the present invention, wherein the cross-section passes through the electrode lead-out portion of the bottom electrode, wherein temperature compensation layers are provided in both the top electrode and the bottom electrode.

[0095] exist Figure 26 In the figure, the upper temperature compensating layer and the lower temperature compensating layer are completely wrapped by the top electrode and the bottom electrode, respectively. L7 is defined as the horizontal distance between the first end of the temperature compensating layer 117 and the first end of the temperature compensating layer 119, which is generally set to 0μm-10μm. L8 is the horizontal distance between the second end of the temperature compensating layer 117 and the second end of the temperature compensating layer 119, which is generally set to 0μm-10μm. Not shown, in the cross section of the non-electrode connection end of the top electrode and the non-electrode connection end of the bottom electrode, the end faces of the upper temperature compensating layer 117 and the lower temperature compensating layer 119 may also have a certain distance in the lateral direction, which is optionally set in the range of 0-10μm.

[0096] As those skilled in the art will appreciate, the temperature compensation layer 119 disposed on the upper side of the piezoelectric layer 111 may also be disposed between the top electrode 115 and the piezoelectric layer 111, and is not limited to being disposed only within the range of the top electrode. Figure 5-15 The arrangement is similar to that of the temperature compensation layer 117 .

[0097] In the present invention, the material of the piezoelectric layer may also be a non-single crystal material.

[0098] It should be pointed out that in the present invention, each numerical range, except for those explicitly stated to not include endpoint values, can be not only endpoint values ​​but also the median of each numerical range, all of which are within the protection scope of the present invention.

[0099] In the present invention, the terms "up" and "down" are relative to the bottom surface of the base of the resonator. 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.

[0100] In the present invention, the terms "inside" and "outside" are relative to the center of the effective area of ​​the resonator in the transverse direction or radial direction. The side or end of a component closer to the center is the inside or inner end, while the side or end of the component farther from the center is the outside or outer end. With respect to a reference position, being located inside the position means being between the position and the center in the transverse direction or radial direction, while being located outside the position means being farther from the center in the transverse direction or radial direction than the position.

[0101] As those skilled in the art will appreciate, the BAW resonator according to the present invention can be used to form filters or other semiconductor devices.

[0102] Based on the above, the present invention proposes the following technical solutions:

[0103] 1. A bulk acoustic wave resonator, comprising:

[0104] substrate;

[0105] Acoustic mirror;

[0106] bottom electrode;

[0107] a top electrode; and

[0108] A piezoelectric layer is provided between the bottom electrode and the top electrode,

[0109] in:

[0110] An acoustic impedance structure is provided between the piezoelectric layer and the substrate;

[0111] The acoustic impedance structure includes a first acoustic impedance layer and a second acoustic impedance layer arranged adjacent to each other in a transverse direction, the first acoustic impedance layer and the second acoustic impedance layer having different acoustic impedances, and the acoustic mirror is located between the first acoustic impedance layers in the transverse direction of the resonator;

[0112] The resonator further includes a temperature compensation layer.

[0113] 2. The resonator according to item 1, wherein:

[0114] At least a portion of the temperature compensation layer is disposed between the piezoelectric layer and the corresponding electrode.

[0115] 3. The resonator according to 2, wherein:

[0116] One end of the temperature compensation layer away from the connection side of the corresponding electrode is covered by the corresponding electrode; or

[0117] One end of the temperature compensation layer away from the connection side of the corresponding electrode extends from the non-connection side of the corresponding electrode.

[0118] 4. The resonator according to item 1, wherein:

[0119] At least a portion of the temperature compensating layer covers at least a portion of the corresponding electrode.

[0120] 5. The resonator according to item 1, wherein:

[0121] At least a portion of the temperature compensation layer is disposed in the corresponding electrode.

[0122] 6. The resonator according to 5, wherein:

[0123] One end of the temperature compensation layer away from the connection edge of the corresponding electrode is arranged in the corresponding electrode and is covered by the corresponding electrode; or

[0124] An end of the temperature compensation layer away from the connection side of the corresponding electrode is flush with the edge of the non-connection side of the corresponding electrode; or

[0125] One end of the temperature compensation layer away from the electrode connection end of the corresponding electrode is located outside the non-connection edge of the corresponding electrode and covers a portion of the surface of the piezoelectric layer.

[0126] 7. The resonator according to 5, wherein:

[0127] The temperature compensation layer is entirely arranged in the corresponding electrode.

[0128] 8. The resonator according to any one of 2 to 7, wherein:

[0129] The temperature compensation layer includes a lower temperature compensation layer arranged below the piezoelectric layer, and the corresponding electrode corresponding to the lower temperature compensation layer is the bottom electrode.

[0130] 9. The resonator according to 8, wherein:

[0131] At the electrode connection end of the bottom electrode, one end of the lower temperature compensation layer close to the electrical connection portion of the bottom electrode is arranged between the non-electrode connection end of the top electrode and the first acoustic impedance layer in the lateral direction; or

[0132] At the electrode connection end of the bottom electrode, one end of the lower temperature compensation layer close to the electrical connection portion of the bottom electrode is arranged outside the non-electrode connection end of the top electrode in the lateral direction and outside the inner end of the first acoustic impedance layer.

[0133] 10. The resonator according to 8, wherein:

[0134] At least a portion of the lower temperature compensation layer is disposed in the bottom electrode;

[0135] The resonator has an electrode lead portion that passes through the piezoelectric layer and is electrically connected to the bottom electrode;

[0136] One end of the lower temperature compensation layer close to the connection edge of the bottom electrode is spaced apart from the electrode lead-out portion in the horizontal direction.

[0137] 11. The resonator according to 8, wherein:

[0138] At least a portion of the lower temperature compensation layer is disposed in the bottom electrode;

[0139] The resonator has an electrode lead portion that passes through the piezoelectric layer and is electrically connected to the bottom electrode;

[0140] The lower temperature compensating layer extends across the entire bottom electrode in the horizontal direction, and one end of the lower temperature compensating layer close to the connecting edge of the bottom electrode extends across the electrode lead-out portion in the horizontal direction;

[0141] The lower temperature compensation layer is provided with a connecting portion, and the connecting portion electrically connects the parts of the bottom electrode located on the upper and lower sides of the lower temperature compensation layer.

[0142] 12. The resonator according to 11, wherein:

[0143] The communication portion includes at least one communication ring arranged in a ring shape.

[0144] 13. The resonator according to 12, wherein:

[0145] The communicating ring includes at least one annular opening, and the annular opening is an annular opening that extends continuously in an annular shape; or

[0146] The communication ring includes a plurality of communication holes, and the plurality of communication holes are arranged in at least one ring shape.

[0147] 14. The resonator according to item 11, wherein:

[0148] The at least one communicating ring includes a plurality of communicating rings arranged concentrically.

[0149] 15. The resonator according to item 11, wherein:

[0150] The communication portion is provided outside the effective area of ​​the resonator.

[0151] 16. The resonator according to 8, wherein:

[0152] At least a portion of the lower temperature compensation layer is disposed in the bottom electrode;

[0153] At the non-electrode connection end of the bottom electrode, an edge of the lower temperature compensation layer is flush with an edge of the non-electrode connection end of the bottom electrode.

[0154] 17. The resonator according to 8, wherein:

[0155] At least a portion of the lower temperature compensation layer covers the lower surface of the bottom electrode.

[0156] 18. The resonator according to 8, wherein:

[0157] The acoustic mirror is an acoustic mirror cavity;

[0158] The portion of the lower temperature compensation layer located between the edges of the acoustic mirror cavity in the lateral direction is covered or wrapped by the bottom electrode and isolated from the acoustic mirror cavity.

[0159] 19. The resonator according to 8, wherein:

[0160] The acoustic mirror is an acoustic mirror cavity;

[0161] At least a portion of the lower temperature compensating layer located between edges of the acoustic mirror cavity in a lateral direction is exposed to the acoustic mirror cavity.

[0162] 20. The resonator according to any one of 8 to 19, wherein:

[0163] The lower temperature compensating layer includes a first extension portion extending in the lateral direction to the outside of the non-electrode connection end of the bottom electrode, the first extension portion is spaced apart from the first acoustic impedance layer in the lateral direction, and an extension length of the first extension portion is in the range of 0-10 μm, or the lower temperature compensating layer includes a first extension portion extending in the lateral direction to the outside of the non-electrode connection end of the bottom electrode, the first extension portion is at least covered by the first acoustic impedance layer and is located between the piezoelectric layer and the acoustic impedance layer; and / or

[0164] The lower temperature compensation layer includes a second extension portion extending to the outside of the electrode connection end of the bottom electrode in the lateral direction, and the second extension portion is at least partially separated from the first acoustic impedance layer in the lateral direction, or the second extension portion is at least covered by the first acoustic impedance layer and is thus located between the piezoelectric layer and the acoustic impedance layer.

[0165] 21. The resonator according to 8, wherein:

[0166] In the lateral direction, one end of the lower temperature compensation layer close to the electrode connection end of the bottom electrode is located inside the non-electrode connection end of the top electrode; or

[0167] In the lateral direction, one end of the lower temperature compensation layer close to the electrode connection end of the bottom electrode is located outside the non-electrode connection end of the top electrode and is spaced apart from the first acoustic impedance layer; or

[0168] In the lateral direction, one end of the electrode connection end of the lower temperature compensating layer close to the bottom electrode is located on the outside of the non-electrode connection end of the top electrode, and in the projection parallel to the thickness direction of the resonator, one end of the electrode connection end of the lower temperature compensating layer close to the bottom electrode overlaps with the first acoustic impedance layer.

[0169] 22. The resonator according to any one of 1 to 7, wherein:

[0170] The temperature compensation layer includes an upper temperature compensation layer arranged above the piezoelectric layer, and the corresponding electrode corresponding to the upper temperature compensation layer is a top electrode.

[0171] 23. The resonator according to 22, wherein:

[0172] At least a portion of the upper temperature compensation layer is disposed in the top electrode.

[0173] 24. The resonator according to 23, wherein:

[0174] In the lateral direction, the outer end of the upper temperature compensation layer is located inside the non-electrode connection end of the bottom electrode; or

[0175] In the lateral direction, the outer end of the upper temperature compensation layer is located outside the non-electrode connection end of the bottom electrode and is spaced apart from the first acoustic impedance layer; or

[0176] In the lateral direction, the outer end of the upper temperature compensation layer is outside the non-electrode connection end of the bottom electrode, and in a projection parallel to the thickness direction of the resonator, the outer end of the upper temperature compensation layer overlaps with the first acoustic impedance layer.

[0177] 24. The resonator according to 22, wherein:

[0178] The resonator comprises an upper temperature compensation layer and a lower temperature compensation layer;

[0179] The upper temperature compensation layer is completely wrapped by the top electrode, and the lower temperature compensation layer is completely wrapped by the bottom electrode; and

[0180] At the non-electrode connection end of the bottom electrode, there is a first distance (L8) in the lateral direction between the end of the lower temperature compensating layer away from the electrode connection end of the bottom electrode and the end of the upper temperature compensating layer close to the electrode connection end of the top electrode; and / or at the non-electrode connection end of the top electrode, there is a second distance (L7) in the lateral direction between the end of the upper temperature compensating layer away from the electrode connection end of the top electrode and the end of the lower temperature compensating layer close to the electrode connection end of the bottom electrode; and / or at the non-electrode connection end of the top electrode and the bottom electrode, there is a third distance in the lateral direction between the ends of the upper temperature compensating layer and the lower temperature compensating layer.

[0181] 25. The resonator according to 23, wherein:

[0182] At least a portion of the upper temperature compensating layer is exposed to the outside of the top electrode.

[0183] 26. The resonator according to 19 or 25, wherein:

[0184] The material of the temperature compensation layer is different from that of the second acoustic impedance layer.

[0185] 27. The resonator according to 26, wherein:

[0186] The material of the second acoustic impedance layer is polysilicon or amorphous silicon, and the material of the temperature compensation layer is silicon dioxide or doped silicon dioxide.

[0187] 28. The resonator according to 27, wherein:

[0188] The material of the first acoustic impedance layer is the same as that of the temperature compensation layer.

[0189] 29. The resonator according to item 1, wherein:

[0190] The widths of the portions of the first acoustic impedance layer and the second acoustic impedance layer that contact the piezoelectric layer are mλ1 / 4 and nλ2 / 4, respectively, where m and n are both odd numbers, and λ1 and λ2 are the wavelengths of acoustic waves propagating laterally at the resonant frequency of the first acoustic impedance layer and the second acoustic impedance layer, respectively.

[0191] 30. The resonator according to item 1, wherein:

[0192] The material forming one of the first acoustic impedance layer and the second acoustic impedance layer is selected from aluminum nitride, silicon dioxide, silicon nitride, polycrystalline silicon, and amorphous silicon, and the material forming the other of the first acoustic impedance layer and the second acoustic impedance layer is selected from silicon dioxide, doped silicon dioxide, polycrystalline silicon, and amorphous silicon. The material forming the first acoustic impedance layer is different from the material forming the second acoustic impedance layer.

[0193] 31. The resonator according to item 1, wherein:

[0194] The acoustic mirror is an acoustic mirror cavity;

[0195] The boundary of the acoustic mirror cavity in the lateral direction of the resonator is defined by the first acoustic impedance layer.

[0196] 32. The resonator according to item 1, wherein:

[0197] The piezoelectric layer is a single crystal piezoelectric layer.

[0198] 33. The resonator according to item 1, wherein:

[0199] In a projection of the temperature compensation layer in the thickness direction of the resonator, at least a portion is located within the effective area of ​​the resonator.

[0200] 34. A filter comprising the bulk acoustic wave resonator according to any one of 1-33.

[0201] 35. An electronic device comprising the filter according to 34 or the bulk acoustic wave resonator according to any one of 1 to 33.

[0202] The electronic equipment here includes but is not limited to intermediate products such as RF front-ends, filter amplification modules, as well as terminal products such as mobile phones, WIFI, and drones.

[0203] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents.

Claims

1. A bulk acoustic wave resonator, comprising: substrate; Acoustic mirror; bottom electrode; Top electrode; and a piezoelectric layer disposed between the bottom electrode and the top electrode, wherein: An acoustic impedance structure and the acoustic mirror are provided between the piezoelectric layer and the substrate; The acoustic impedance structure includes a first acoustic impedance layer and a second acoustic impedance layer arranged adjacent to each other in a transverse direction, the first acoustic impedance layer and the second acoustic impedance layer having different acoustic impedances, the first acoustic impedance layer being arranged around the acoustic mirror, and the acoustic mirror being located between the first acoustic impedance layers in the transverse direction of the resonator; The resonator further includes a temperature compensation layer.

2. The resonator according to claim 1, wherein: At least a portion of the temperature compensation layer is disposed between the piezoelectric layer and the corresponding electrode.

3. The resonator according to claim 2, wherein: One end of the temperature compensation layer away from the connection side of the corresponding electrode is covered by the corresponding electrode; or One end of the temperature compensation layer away from the connection side of the corresponding electrode extends from the non-connection side of the corresponding electrode.

4. The resonator according to claim 1, wherein: At least a portion of the temperature compensating layer covers at least a portion of the corresponding electrode.

5. The resonator according to claim 1, wherein: At least a portion of the temperature compensation layer is disposed in the corresponding electrode.

6. The resonator according to claim 5, wherein: One end of the temperature compensation layer away from the connection edge of the corresponding electrode is arranged in the corresponding electrode and is covered by the corresponding electrode; or An end of the temperature compensation layer away from the connection side of the corresponding electrode is flush with the edge of the non-connection side of the corresponding electrode; or One end of the temperature compensation layer away from the electrode connection end of the corresponding electrode is located outside the non-connection edge of the corresponding electrode and covers a portion of the surface of the piezoelectric layer.

7. The resonator according to claim 5, wherein: The temperature compensation layer is entirely arranged in the corresponding electrode.

8. The resonator according to any one of claims 2 to 7, wherein: The temperature compensation layer includes a lower temperature compensation layer arranged below the piezoelectric layer, and the corresponding electrode corresponding to the lower temperature compensation layer is the bottom electrode.

9. The resonator of claim 8, wherein: At the electrode connection end of the bottom electrode, one end of the lower temperature compensation layer close to the electrical connection portion of the bottom electrode is arranged between the non-electrode connection end of the top electrode and the first acoustic impedance layer in the lateral direction; or At the electrode connection end of the bottom electrode, one end of the lower temperature compensation layer close to the electrical connection portion of the bottom electrode is arranged outside the non-electrode connection end of the top electrode in the lateral direction and outside the inner end of the first acoustic impedance layer.

10. The resonator of claim 8, wherein: At least a portion of the lower temperature compensation layer is disposed in the bottom electrode; The resonator has an electrode lead portion that passes through the piezoelectric layer and is electrically connected to the bottom electrode; One end of the lower temperature compensation layer close to the connection edge of the bottom electrode is spaced apart from the electrode lead-out portion in the horizontal direction.

11. The resonator according to claim 8, wherein: At least a portion of the lower temperature compensation layer is disposed in the bottom electrode; The resonator has an electrode lead portion that passes through the piezoelectric layer and is electrically connected to the bottom electrode; The lower temperature compensating layer extends across the entire bottom electrode in the horizontal direction, and one end of the lower temperature compensating layer close to the connecting edge of the bottom electrode extends across the electrode lead-out portion in the horizontal direction; The lower temperature compensation layer is provided with a connecting portion, and the connecting portion electrically connects the parts of the bottom electrode located on the upper and lower sides of the lower temperature compensation layer.

12. The resonator of claim 11, wherein: The communication portion includes at least one communication ring arranged in a ring shape.

13. The resonator of claim 12, wherein: The communication ring includes at least one annular opening portion, and the annular opening portion is an annular opening that extends continuously in an annular shape; Alternatively, the communication ring includes a plurality of communication holes, and the plurality of communication holes are arranged in at least one ring shape.

14. The resonator of claim 11 , wherein: The at least one communicating ring includes a plurality of communicating rings arranged concentrically.

15. The resonator of claim 11, wherein: The communication portion is provided outside the effective area of ​​the resonator.

16. The resonator of claim 8, wherein: At least a portion of the lower temperature compensation layer is disposed in the bottom electrode; At the non-electrode connection end of the bottom electrode, an edge of the lower temperature compensation layer is flush with an edge of the non-electrode connection end of the bottom electrode.

17. The resonator of claim 8, wherein: At least a portion of the lower temperature compensation layer covers the lower surface of the bottom electrode.

18. The resonator of claim 8, wherein: The acoustic mirror is an acoustic mirror cavity; The portion of the lower temperature compensation layer located between the edges of the acoustic mirror cavity in the lateral direction is covered or wrapped by the bottom electrode and isolated from the acoustic mirror cavity.

19. The resonator of claim 8, wherein: The acoustic mirror is an acoustic mirror cavity; At least a portion of the lower temperature compensating layer located between edges of the acoustic mirror cavity in a lateral direction is exposed to the acoustic mirror cavity.

20. The resonator according to any one of claims 9 to 19, wherein: The lower temperature compensating layer includes a first extension portion extending in the lateral direction to the outside of the non-electrode connection end of the bottom electrode, the first extension portion is spaced apart from the first acoustic impedance layer in the lateral direction, and an extension length of the first extension portion is in the range of 0-10 μm, or the lower temperature compensating layer includes a first extension portion extending in the lateral direction to the outside of the non-electrode connection end of the bottom electrode, the first extension portion is at least covered by the first acoustic impedance layer and is located between the piezoelectric layer and the acoustic impedance layer; and / or The lower temperature compensation layer includes a second extension portion extending to the outside of the electrode connection end of the bottom electrode in the lateral direction, and the second extension portion is at least partially separated from the first acoustic impedance layer in the lateral direction, or the second extension portion is at least covered by the first acoustic impedance layer and is thus located between the piezoelectric layer and the acoustic impedance layer.

21. The resonator of claim 8, wherein: In the lateral direction, one end of the lower temperature compensation layer close to the electrode connection end of the bottom electrode is located inside the non-electrode connection end of the top electrode; or In the lateral direction, one end of the lower temperature compensation layer close to the electrode connection end of the bottom electrode is located outside the non-electrode connection end of the top electrode and is spaced apart from the first acoustic impedance layer; or In the lateral direction, one end of the electrode connection end of the lower temperature compensating layer close to the bottom electrode is located on the outside of the non-electrode connection end of the top electrode, and in the projection parallel to the thickness direction of the resonator, one end of the electrode connection end of the lower temperature compensating layer close to the bottom electrode overlaps with the first acoustic impedance layer.

22. The resonator according to any one of claims 1 to 7, wherein: The temperature compensation layer includes an upper temperature compensation layer arranged above the piezoelectric layer, and the corresponding electrode corresponding to the upper temperature compensation layer is a top electrode.

23. The resonator of claim 22, wherein: At least a portion of the upper temperature compensation layer is disposed in the top electrode.

24. The resonator of claim 23, wherein: In the lateral direction, the outer end of the upper temperature compensation layer is located inside the non-electrode connection end of the bottom electrode; or In the lateral direction, the outer end of the upper temperature compensation layer is located outside the non-electrode connection end of the bottom electrode and is spaced apart from the first acoustic impedance layer; or In the lateral direction, the outer end of the upper temperature compensation layer is outside the non-electrode connection end of the bottom electrode, and in a projection parallel to the thickness direction of the resonator, the outer end of the upper temperature compensation layer overlaps with the first acoustic impedance layer.

25. The resonator of claim 22, wherein: The resonator comprises an upper temperature compensation layer and a lower temperature compensation layer; The upper temperature compensation layer is completely wrapped by the top electrode, and the lower temperature compensation layer is completely wrapped by the bottom electrode; and At the non-electrode connection end of the bottom electrode, there is a first distance (L8) in the lateral direction between the end of the lower temperature compensating layer away from the electrode connection end of the bottom electrode and the end of the upper temperature compensating layer close to the electrode connection end of the top electrode; and / or at the non-electrode connection end of the top electrode, there is a second distance (L7) in the lateral direction between the end of the upper temperature compensating layer away from the electrode connection end of the top electrode and the end of the lower temperature compensating layer close to the electrode connection end of the bottom electrode; and / or at the non-electrode connection end of the top electrode and the bottom electrode, there is a third distance in the lateral direction between the ends of the upper temperature compensating layer and the lower temperature compensating layer.

26. The resonator of claim 23, wherein: At least a portion of the upper temperature compensating layer is exposed to the outside of the top electrode.

27. The resonator of claim 19 or 25, wherein: The material of the temperature compensation layer is different from that of the second acoustic impedance layer.

28. The resonator of claim 26, wherein: The material of the second acoustic impedance layer is polysilicon or amorphous silicon, and the material of the temperature compensation layer is silicon dioxide or doped silicon dioxide.

29. The resonator of claim 27, wherein: The material of the first acoustic impedance layer is the same as that of the temperature compensation layer.

30. The resonator of claim 1 , wherein: The widths of the portions of the first acoustic impedance layer and the second acoustic impedance layer that contact the piezoelectric layer are mλ1 / 4 and nλ2 / 4, respectively, where m and n are both odd numbers, and λ1 and λ2 are the wavelengths of acoustic waves propagating laterally at the resonant frequency of the first acoustic impedance layer and the second acoustic impedance layer, respectively.

31. The resonator of claim 1 , wherein: The material forming one of the first acoustic impedance layer and the second acoustic impedance layer is selected from aluminum nitride, silicon dioxide, silicon nitride, polycrystalline silicon, and amorphous silicon, and the material forming the other of the first acoustic impedance layer and the second acoustic impedance layer is selected from silicon dioxide, doped silicon dioxide, polycrystalline silicon, and amorphous silicon. The material forming the first acoustic impedance layer is different from the material forming the second acoustic impedance layer.

32. The resonator of claim 1 , wherein: The acoustic mirror is an acoustic mirror cavity; The boundary of the acoustic mirror cavity in the lateral direction of the resonator is defined by the first acoustic impedance layer.

33. The resonator of claim 1 , wherein: The piezoelectric layer is a single crystal piezoelectric layer.

34. The resonator of claim 1 , wherein: In a projection of the temperature compensation layer in the thickness direction of the resonator, at least a portion is located within the effective area of ​​the resonator.

35. A filter comprising the bulk acoustic wave resonator according to any one of claims 1 to 33.

36. An electronic device comprising the filter according to claim 35 or the bulk acoustic wave resonator according to any one of claims 1 to 34.

Images