Film bulk acoustic resonator and preparation method thereof

Abstract

The invention relates to the technical field of semiconductor devices, and particularly discloses a film bulk acoustic resonator and a preparation method thereof, and the film bulk acoustic resonator comprises a substrate, and a lower electrode, a piezoelectric layer, an upper electrode and a passivation layer which are stacked on the substrate; the overlapped part of the projections of the lower electrode, the piezoelectric layer and the upper electrode on the substrate is an active area; a compensation layer is further formed on the piezoelectric layer, a hollow groove is formed in the compensation layer, and the hollow groove is formed along the projection edge of the active area, so that the passivation layer collapses at the position covering the hollow groove to form a groove. Through the hollow design of the compensation layer, a groove is naturally formed in the surface of the passivation layer above the compensation layer, and the manufacturing yield is effectively improved.

Description

Technical Field

[0001] The present application relates to the technical field of semiconductor devices, and in particular to a thin film bulk acoustic wave resonator and a method for preparing the same. Background Art

[0002] In a thin film bulk acoustic resonator (FBAR), a groove structure is usually set in the active area. The groove structure is set to eliminate the parasitic effect on the left side of the FBAR test impedance curve. However, when the width or depth of the groove structure is unreasonable, it is easy to cause parasitic problems on the right side of the test impedance curve. When the depth of the groove structure is too shallow or the width is too narrow, the effect of eliminating the parasitic on the left side will be reduced. The prior art uses etching to form grooves on the surface of the passivation layer. Unlike general etching processes, the etching depth of the groove structure generally does not exceed 100nm, which is less than the thickness of the film to be etched, so there is no need to etch through the film to be etched. The depth of the groove structure is generally controlled by controlling the etching time and calculating the average etching rate. First, the etching rate will change with the depth of the groove, so controlling the size by the etching rate and etching time method will cause a large error. Second, the film thickness distribution on the entire wafer is uneven, and the etching rates at the center and edge of the wafer are also inconsistent, so it is difficult to control the depth change of the groove. Based on the above factors, the yield of the groove structure prepared by the prior art is extremely low, resulting in parasitic problems still existing in the impedance curve, which is not conducive to improving the performance of the device. Summary of the invention

[0003] The purpose of the present application is to provide a thin film bulk acoustic wave resonator and a preparation method thereof, which hollows out the compensation layer so that a groove is naturally formed on the surface of the passivation layer above the compensation layer, thereby effectively improving the manufacturing yield.

[0004] The embodiment of the present application is implemented as follows:

[0005] In the first aspect, an embodiment of the present application provides a thin film bulk acoustic wave resonator, including a substrate and a lower electrode, a piezoelectric layer, an upper electrode and a passivation layer stacked on the substrate; the overlapping portion of the lower electrode, the piezoelectric layer and the upper electrode projected on the substrate is an active area; a compensation layer is also formed on the piezoelectric layer, and a hollow groove is formed on the compensation layer, and the hollow groove is formed along the projected edge of the active area, so that the passivation layer collapses at the position covering the hollow groove to form a groove.

[0006] As an optional implementation, the compensation layer is located between the upper electrode and the passivation layer.

[0007] As an optional implementation, the compensation layer is located between the piezoelectric layer and the upper electrode, and the compensation layer is made of metal material.

[0008] As an optional implementation, the upper electrode includes a first upper electrode and a second upper electrode which are stacked, and the compensation layer is located between the first upper electrode and the second upper electrode.

[0009] As an optional implementation, the hollow groove includes an annular hollow groove extending circumferentially along the projected edge of the active area and connected end to end.

[0010] As an optional implementation, the hollow groove includes a plurality of strip-shaped hollow grooves arranged at intervals around the projected edge of the active area; each strip-shaped hollow groove extends along the projected edge path of the active area.

[0011] As an optional implementation, a thickening layer is provided between the piezoelectric layer and the upper electrode, and an air wing and an air bridge are formed between the thickening layer and the piezoelectric layer; the projection of the compensation layer on the substrate and the projection of the thickening layer on the substrate have an overlapping portion.

[0012] As an optional implementation, a columnar structure arranged at intervals is provided in the air bridge; the extension direction of the columnar structure is perpendicular to the substrate, one end of the columnar structure is connected to the piezoelectric layer, and the other end is in contact with the thickening layer.

[0013] In a second aspect, an embodiment of the present application provides a method for preparing a thin film bulk acoustic wave resonator, the method comprising:

[0014] A lower electrode and a piezoelectric layer are sequentially arranged on the substrate;

[0015] An upper electrode is arranged on the piezoelectric layer; the overlapping portion of the lower electrode, the piezoelectric layer and the upper electrode projected on the substrate is an active area;

[0016] A compensation layer is arranged on the substrate formed with the piezoelectric layer, and an edge position of the compensation layer corresponding to the projection of the active area is hollowed out to form a hollow groove;

[0017] A passivation layer is disposed on the compensation layer so that the passivation layer collapses at a position covering the hollow groove to form a groove.

[0018] Furthermore, an upper electrode is provided on the piezoelectric layer, comprising:

[0019] Sequentially forming a first upper electrode and a second upper electrode on the upper surface of the piezoelectric layer;

[0020] A compensation layer is provided on a substrate having a piezoelectric layer, comprising:

[0021] A compensation layer is arranged on the surface of the first upper electrode, so that the second upper electrode is laid on the upper surface of the compensation layer.

[0022] Furthermore, before arranging the upper electrode on the piezoelectric layer, the method includes:

[0023] forming a first sacrificial layer and a second sacrificial layer on opposite sides of the active region on the piezoelectric layer;

[0024] forming a thickening layer on the first sacrificial layer and the second sacrificial layer;

[0025] After the passivation layer is provided on the compensation layer, the following steps are included:

[0026] The first sacrificial layer and the second sacrificial layer are released to form air wings and air bridges between the thickened layer and the piezoelectric layer.

[0027] The beneficial effects of the embodiments of the present application include:

[0028] In the first aspect, the embodiment of the present application provides a thin film bulk acoustic wave resonator, including a substrate and a lower electrode, a piezoelectric layer, an upper electrode and a passivation layer stacked on the substrate; the overlapping portion of the lower electrode, the piezoelectric layer and the upper electrode projected on the substrate is an active area; the embodiment of the present application also forms a compensation layer above the piezoelectric layer, and a hollow groove is formed on the compensation layer, and the hollow groove is formed along the projected edge of the active area, so that the passivation layer collapses at the position covering the hollow groove to form a groove. Compared with the prior art, the embodiment of the present application sets a compensation layer and hollows the compensation layer, so that the passivation layer naturally collapses at the position covering the hollow groove to form a groove. The embodiment of the present application can avoid etching the passivation layer and directly form a groove of a predetermined size on the passivation layer. Among them, the precise setting of the groove on the surface of the passivation layer can be achieved by controlling the thickness of the compensation layer and the width of the hollow groove. Compared with the prior art, the embodiment of the present application can effectively improve the manufacturing yield.

[0029] In the second aspect, the embodiment of the present application provides a method for preparing a thin film bulk acoustic wave resonator, including: sequentially arranging a lower electrode and a piezoelectric layer on a substrate; arranging an upper electrode on the piezoelectric layer; the overlapping portion of the projection of the lower electrode, the piezoelectric layer and the upper electrode on the substrate is an active area; arranging a compensation layer on the substrate formed with the piezoelectric layer, hollowing out the edge position of the projection of the compensation layer corresponding to the active area to form a hollowed-out groove; arranging a passivation layer on the compensation layer so that the passivation layer collapses at the position covering the hollowed-out groove to form a groove. The embodiment of the present application uses the compensation layer to hollow out to form a hollowed-out groove, so that a groove is formed on the surface of the passivation layer, and the depth of the groove is consistent with the thickness of the compensation layer. Different from the prior art, the embodiment of the present application does not need to etch the passivation layer, and does not need to control the etching time, average etching rate and other data of the passivation layer to control the groove depth. The direct hollowing of the compensation layer is used to achieve the precise setting of the groove on the surface of the passivation layer, avoiding the size fluctuation when setting the groove structure. The embodiment of the present application can accurately control the depth of the groove. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0031] Figure 1 This is one of the structural schematic diagrams of the thin film bulk acoustic resonator according to an embodiment of the present application;

[0032] Figure 2 This is the second structural schematic diagram of the thin film bulk acoustic wave resonator according to the embodiment of the present application;

[0033] Figure 3 This is the third structural diagram of the thin film bulk acoustic resonator according to the embodiment of the present application;

[0034] Figure 4 This is the fourth structural diagram of the thin film bulk acoustic resonator according to the embodiment of the present application;

[0035] Figure 5 This is the fifth structural diagram of the thin film bulk acoustic wave resonator according to the embodiment of the present application;

[0036] Figure 6 This is the sixth structural diagram of the thin film bulk acoustic resonator according to the embodiment of the present application;

[0037] Figure 7 This is the seventh structural diagram of the thin film bulk acoustic wave resonator according to the embodiment of the present application;

[0038] Figure 8 This is the eighth structural schematic diagram of the thin film bulk acoustic wave resonator according to the embodiment of the present application.

[0039] icon:

[0040] 100-substrate; 101-lower electrode; 102-piezoelectric layer; 103-upper electrode; 104-passivation layer; 105-compensation layer; 106-groove; 107-first upper electrode; 108-second upper electrode; 109-thickening layer; 110-air wing; 111-air bridge; 112-columnar structure; 113-cavity; 114-aluminum nitride seed layer; 115-tilt angle; 116-left sacrificial layer; 117-right sacrificial layer; 118-lead hole. DETAILED DESCRIPTION

[0041] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0042] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for which protection is sought, but merely represents selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0043] It should be noted that similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in the subsequent drawings. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0044] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0045] In a thin film bulk acoustic resonator (FBAR), a groove structure is usually set in the active area, and the parasitic effect on the left side of the FBAR test impedance curve is eliminated by the groove structure. However, when the width or depth of the groove structure is unreasonable, it is easy to cause parasitic problems on the right side of the test impedance curve. When the depth of the groove structure is too shallow or the width is too narrow, the effect of eliminating the parasitic on the left side will be reduced. The prior art is to form a groove on the surface of the passivation layer 104 by etching. Unlike the general etching process, the etching depth of the groove structure generally does not exceed 100nm, which is less than the thickness of the film to be etched, so it is not necessary to etch through the film to be etched. The depth of the groove structure is generally controlled by controlling the etching time and calculating the average etching rate. First, the etching rate will change with the depth of the groove, so controlling the size by the etching rate and etching time method will cause a large error. Second, the film thickness distribution on the entire wafer is uneven, and the etching rates at the center and edge of the wafer are also inconsistent, so it is difficult to control the depth change of the groove. Based on the above factors, the yield of the groove structure prepared by the prior art is extremely low, resulting in parasitic problems still existing in the impedance curve, which is not conducive to improving the performance of the device.

[0046] In order to solve the above technical problems, the embodiments of the present application provide a thin film bulk acoustic wave resonator and a method for preparing the same.

[0047] First, refer to Figure 1 , Figure 2 as well as Figure 3 As shown, an embodiment of the present application provides a thin film bulk acoustic wave resonator, including a substrate 100 and a lower electrode 101, a piezoelectric layer 102, an upper electrode 103 and a passivation layer 104 stacked on the substrate 100; the overlapping portion of the lower electrode 101, the piezoelectric layer 102 and the upper electrode 103 projected on the substrate 100 is an active area; a compensation layer 105 is also formed on the piezoelectric layer 102, and a hollow groove is formed on the compensation layer 105, and the hollow groove is formed along the projected edge of the active area, so that the passivation layer 104 collapses at a position covering the hollow groove to form a groove 106.

[0048] It should be noted that the depth of the groove 106 formed on the surface of the passivation layer 104 is:

[0049] The thickness of the compensation layer 105 in the embodiment of the present application is equal to the depth of the groove 106 formed by the collapse of the passivation layer 104 at the position covering the hollow groove. Exemplarily, the compensation layer 105 with a thickness of 80 nm is set, and after the compensation layer 105 is hollowed out, the passivation layer 104 collapses at the position covering the hollow groove to form a groove 106 with a depth of 80 nm.

[0050] It should be noted that the thickness distance data of the compensation layer 105 can be set by those skilled in the art according to the depth requirements of the groove 106, and there is no special limitation on this. For example, the thickness of the compensation layer 105 is 30-100 nm.

[0051] Regarding the width of the groove 106 formed on the surface of the passivation layer 104, it should be noted that:

[0052] The width of the hollow groove on the compensation layer 105 is equal to the width of the groove 106 on the passivation layer 104. By controlling the width of the hollow groove of the compensation layer 105, the width of the groove 106 on the surface of the passivation layer 104 can be controlled.

[0053] It should be noted that the hollowing process of the compensation layer 105 in the embodiment of the present application can be performed by etching, photolithography or other types of hollowing technology. Compared with the prior art that directly etches the passivation layer 104, the etching of the compensation layer 105 in the embodiment of the present application can directly etch through the compensation layer 105, and use the hierarchical structure below the compensation layer 105 as a stop layer to ensure the accuracy of the hollowing groove depth. The prior art directly etches the passivation layer 104, which cannot directly etch through the passivation layer 104, resulting in the problem that the depth of the groove 106 is difficult to control.

[0054] The embodiment of the present application essentially avoids etching the passivation layer 104 and directly forms a groove 106 of a predetermined size on the passivation layer 104. The precise setting of the groove 106 on the surface of the passivation layer 104 can be achieved by controlling the thickness of the compensation layer 105 and the width of the hollow groove. Compared with the prior art, the embodiment of the present application can effectively improve the manufacturing yield.

[0055] Regarding the specific shape of the groove 106 , those skilled in the art can set it according to needs, and there is no special limitation on this.

[0056] Exemplarily, the hollow grooves include a plurality of strip-shaped hollow grooves arranged at intervals around the projected edge of the active area; each strip-shaped hollow groove extends along the projected edge path of the active area.

[0057] As an optional implementation, the hollow groove includes an annular hollow groove extending circumferentially along the projected edge of the active area and connected end to end.

[0058] Regarding the specific location of the compensation layer 105, it should be noted that:

[0059] The compensation layer 105 needs to be arranged below the passivation layer 104 and above the piezoelectric layer 102 , and specifically includes the following arrangement schemes.

[0060] First, refer to Figure 1 As shown, the compensation layer 105 is located between the upper electrode 103 and the passivation layer 104 .

[0061] Second, refer to Figure 2 As shown, the compensation layer 105 is located between the piezoelectric layer 102 and the upper electrode 103 , and the compensation layer 105 is made of metal material.

[0062] When the compensation layer 105 is located between the piezoelectric layer 102 and the upper electrode 103, the compensation layer 105 is made of a metal material to ensure that the piezoelectric layer 102 and the upper electrode 103 have an effective electrical connection surface in the active region.

[0063] Third, refer to Figure 3 As shown, the upper electrode 103 includes a first upper electrode 107 and a second upper electrode 108 which are stacked, and the compensation layer 105 is located between the first upper electrode 107 and the second upper electrode 108 .

[0064] It should be noted that when the compensation layer 105 is located on the surface of the piezoelectric layer 102, the hierarchical structure above the compensation layer 105 will naturally collapse, ensuring that the groove 106 can be generated on the surface of the uppermost passivation layer 104. Similarly, when the compensation layer 105 is located on the surface of the first upper electrode 107, the hierarchical structure above the compensation layer 105 will naturally collapse, ensuring that the groove 106 can be generated on the surface of the uppermost passivation layer 104.

[0065] For setting the groove 106, the first solution is the preferred setting method, which is to directly set the compensation layer 105 on the lower surface of the passivation layer 104, so that a high-precision groove 106 structure can be formed on the surface of the passivation layer 104. It can avoid interposing other hierarchical structures between the compensation layer 105 and the passivation layer 104 to affect the accuracy of the groove 106 structure.

[0066] As an optional embodiment, a thickening layer 109 is provided between the piezoelectric layer 102 and the upper electrode 103, and an air wing 110 and an air bridge 111 are formed between the thickening layer 109 and the piezoelectric layer 102; the projection of the compensation layer 105 on the substrate 100 and the projection of the thickening layer 109 on the substrate 100 have an overlapping portion.

[0067] Furthermore, the embodiment of the present application enables the compensation layer 105 to fall in the thickened layer 109 region through the above arrangement. On the one hand, the compensation layer 105 can thicken the thickened layer 109 region to improve the quality factor of the resonator. On the other hand, the compensation layer 105 is made of low acoustic impedance materials such as silicon dioxide, and the high acoustic impedance material below the compensation layer 105 forms an acoustic reflection layer. The acoustic reflection layer can reflect the longitudinal waves in the resonator, effectively reduce the parasitic mode of the resonator and improve the quality factor of the resonator.

[0068] Exemplarily, the lower electrode 101 may be made of a high acoustic impedance material such as Mo.

[0069] More preferably, the compensation layer 105 of the embodiment of the present application may be made of a material having a temperature drift coefficient opposite to that of the resonator, so as to compensate for the temperature drift coefficient of the resonator and improve the frequency temperature stability of the resonator.

[0070] Exemplarily, the compensation layer 105 may be made of a positive temperature coefficient material such as silicon dioxide, silicon oxyfluoride, polysilicon, borophosphate glass, etc.

[0071] As an optional embodiment, spaced columnar structures 112 are provided in the air bridge 111 ; the extension direction of the columnar structure 112 is perpendicular to the substrate 100 , one end of the columnar structure 112 is connected to the piezoelectric layer 102 , and the other end is in contact with the thickening layer 109 .

[0072] Reference Figure 4 As shown, in the embodiment of the present application, two spaced-apart columnar structures are formed in the air bridge 111 between the thickened layer 109 and the piezoelectric layer 102, and the piezoelectric layer 102 is specifically inclined in the air bridge, the first columnar structure is arranged near the upper end of the inclined surface, and the second columnar structure is arranged near the lower end of the inclined surface.

[0073] It should be noted that the columnar structure can be made of metal materials such as molybdenum, aluminum, copper, and gold. On the one hand, the embodiment of the present application greatly increases the metal area through the setting of the columnar structure, which is beneficial to improving the heat dissipation capacity of the device. On the other hand, the embodiment of the present application can play a longitudinal supporting role through the columnar structure and divide the air bridge 111 into multiple air cavities, which is beneficial to the lateral reflection of sound waves.

[0074] In a second aspect, an embodiment of the present application provides a method for preparing a thin film bulk acoustic wave resonator, the method comprising:

[0075] A lower electrode 101 and a piezoelectric layer 102 are sequentially arranged on a substrate 100;

[0076] An upper electrode 103 is disposed on the piezoelectric layer 102; the overlapping portion of the lower electrode 101, the piezoelectric layer 102 and the upper electrode 103 projected on the substrate 100 is an active area;

[0077] A compensation layer 105 is provided on the substrate 100 on which the piezoelectric layer 102 is formed, and an edge position of the compensation layer 105 corresponding to the projection of the active area is hollowed out to form a hollow groove;

[0078] The passivation layer 104 is disposed on the compensation layer 105 , so that the passivation layer 104 collapses at a position covering the hollow groove to form a groove 106 .

[0079] Regarding the arrangement of the compensation layer 105 on the substrate 100 on which the piezoelectric layer 102 is formed, it should be noted that:

[0080] The compensation layer 105 may be disposed between the piezoelectric layer 102 and the upper electrode 103 , or may be disposed between the upper electrode 103 and the passivation layer 104 .

[0081] That is, the compensation layer 105 may be disposed on the piezoelectric layer 102 first, and then the stacked upper electrode 103 and the passivation layer 104 may be formed on the compensation layer 105 in sequence.

[0082] Alternatively, an upper electrode 103 may be disposed on the piezoelectric layer 102 , and then a compensation layer 105 and a passivation layer 104 may be stacked and formed on the surface of the upper electrode 103 in sequence.

[0083] The embodiment of the present application uses the compensation layer 105 to hollow out to form a hollow groove, so that a groove 106 is formed on the surface of the passivation layer 104, and the depth of the groove 106 is consistent with the thickness of the compensation layer 105. Different from the prior art, the embodiment of the present application does not need to etch the passivation layer 104, and does not need to control the etching time, average etching rate and other data of the passivation layer 104 to control the depth of the groove 106. The groove 106 on the surface of the passivation layer 104 is accurately set by directly hollowing out the compensation layer 105, avoiding the size fluctuation when setting the groove 106 structure. The embodiment of the present application can accurately control the depth of the groove 106.

[0084] Furthermore, an upper electrode 103 is provided on the piezoelectric layer 102, comprising:

[0085] A first upper electrode 107 and a second upper electrode 108 are sequentially formed on the upper surface of the piezoelectric layer 102;

[0086] A compensation layer 105 is provided on a substrate 100 having a piezoelectric layer 102, comprising:

[0087] The compensation layer 105 is disposed on the surface of the first upper electrode 107 , so that the second upper electrode 108 is laid on the upper surface of the compensation layer 105 .

[0088] Furthermore, before the upper electrode 103 is provided on the piezoelectric layer 102, the method includes:

[0089] forming a first sacrificial layer and a second sacrificial layer on opposite sides of the active region on the piezoelectric layer 102;

[0090] forming a thickening layer 109 on the first sacrificial layer and the second sacrificial layer;

[0091] After the passivation layer 104 is disposed on the compensation layer 105, the method further comprises:

[0092] Reference Figure 1 , Figure 2 as well as Figure 3As shown, the first sacrificial layer and the second sacrificial layer are released to form an air wing 110 and an air bridge 111 between the thickened layer 109 and the piezoelectric layer 102 .

[0093] Specifically, the preparation steps of the embodiment of the present application are as follows:

[0094] (1)Reference Figure 5 As shown, firstly, a cavity 113 is etched on the substrate 100 and a cavity sacrificial layer structure is filled in the cavity 113 , and then the cavity sacrificial layer is polished by a chemical mechanical polishing method until the substrate 100 is flush with the cavity sacrificial layer.

[0095] (2)Reference Figure 5 As shown, an aluminum nitride seed layer 114 is deposited on the substrate 100 , which can enable the lower electrode 101 and the piezoelectric layer 102 to have a better lattice orientation.

[0096] (3)Reference Figure 6 As shown, a lower electrode 101 is deposited and patterned on the aluminum nitride seed layer 114. The lower electrode 101 has a tilt angle 115, which is controlled to be as small as possible to facilitate the subsequent growth of the piezoelectric layer 102. Exemplarily, the tilt angle 115 is between 0° and 30°.

[0097] (4)Reference Figure 6 As shown, a piezoelectric layer 102 is deposited and patterned to form an extraction hole 118 .

[0098] It should be noted that the c-axis preferential orientation growth of the piezoelectric layer 102 depends on a flat surface, that is, the smaller the inclination angle 115 of the lower electrode 101 is, the higher the crystal quality of the piezoelectric layer 102 there is.

[0099] (5)Reference Figure 7 As shown, a sacrificial layer is deposited and patterned on the piezoelectric layer 102 to form a left sacrificial layer 116 for forming the air wing 110 and a right sacrificial layer 117 for forming the air bridge 111 .

[0100] (6)Reference Figure 8 As shown, a thickening layer 109 is deposited and patterned, including a left thickening layer above the left sacrificial layer 116 and a thickening layer 109 above the right sacrificial layer 117. In addition, there is a thickening layer 109 falling on the lead-out hole 118 of the piezoelectric layer 102. When the thickening layer 109 is a metal material, the thickening layer 109 falling on the lead-out hole 118 has the function of leading out the lower electrode 101.

[0101] (7)Reference Figure 8 As shown, the upper electrode 103 is deposited and patterned, including the upper electrode 103 in the lower electrode lead-out area on the left side. The upper electrode 103 falling on the lead-out hole 118 also has the function of leading out the lower electrode 101.

[0102] (8)Reference Figure 1 , Figure 3 and Figure 4 As shown, a compensation layer 105 is deposited and patterned on the upper electrode 103. The compensation layer 105 is located in the active area and is hollowed out to form a recessed area.

[0103] (9)Reference Figure 1 , Figure 3 and Figure 4 As shown, a passivation layer 104 is deposited on the upper surface of the compensation layer 105 . Since the height difference is formed by the compensation layer 105 in the previous step, there is no need to etch the recessed area additionally, and a groove 106 is automatically formed on the passivation layer 104 .

[0104] (10) Patterning the passivation layer 104 to form a lower electrode passivation layer lead-out hole and an upper electrode passivation layer lead-out hole, respectively, and covering the passivation layer with a protective layer material, wherein the protective layer material can be set to gold.

[0105] (11) Etching the release hole structure: To open the release hole, the passivation layer 104, the piezoelectric layer 102 and the aluminum nitride seed layer 114 are sequentially etched.

[0106] (12)Reference Figure 1 As shown, the cavity sacrificial layer, the left sacrificial layer 116 , and the right sacrificial layer 117 are released by a dry method or a wet method to form the cavity 113 , the air wing 110 , and the air bridge 111 .

[0107] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A thin film bulk acoustic resonator, characterized in that: The invention comprises a substrate (100), and a lower electrode (101), a piezoelectric layer (102), an upper electrode (103) and a passivation layer (104) stacked on the substrate (100); the overlapping portion of the lower electrode (101), the piezoelectric layer (102) and the upper electrode (103) projected on the substrate (100) is an active area; a compensation layer (105) is also formed on the piezoelectric layer (102), and a hollow groove is formed on the compensation layer (105), and the hollow groove is formed along the projected edge of the active area, so that the passivation layer (104) collapses at a position covering the hollow groove to form a groove (106).

2. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The compensation layer (105) is located between the upper electrode (103) and the passivation layer (104).

3. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The compensation layer (105) is located between the piezoelectric layer (102) and the upper electrode (103), and the compensation layer (105) is made of a metal material.

4. The thin film bulk acoustic wave resonator according to claim 1, characterized in that: The upper electrode (103) comprises a first upper electrode (107) and a second upper electrode (108) which are stacked, and the compensation layer (105) is located between the first upper electrode (107) and the second upper electrode (108).

5. The thin film bulk acoustic resonator according to any one of claims 1 to 4, characterized in that: The hollow groove comprises an annular hollow groove extending circumferentially along the projected edge of the active area and connected end to end.

6. The thin film bulk acoustic resonator according to any one of claims 1 to 4, characterized in that: The hollow grooves include a plurality of strip-shaped hollow grooves arranged at intervals around the projected edge of the active area; each of the strip-shaped hollow grooves extends along the projected edge path of the active area.

7. The thin film bulk acoustic resonator according to any one of claims 1 to 4, characterized in that: A thickening layer (109) is provided between the piezoelectric layer (102) and the upper electrode (103), and an air wing (110) and an air bridge (111) are formed between the thickening layer (109) and the piezoelectric layer (102); a projection of the compensation layer (105) on the substrate (100) and a projection of the thickening layer (109) on the substrate (100) have an overlapping portion.

8. The thin film bulk acoustic wave resonator according to claim 7, characterized in that: Columnar structures (112) are arranged at intervals in the air bridge (111); the extension direction of the columnar structure (112) is perpendicular to the substrate (100); one end of the columnar structure (112) is connected to the piezoelectric layer (102) and the other end is in contact with the thickening layer (109).

9. A method for preparing a thin film bulk acoustic wave resonator, characterized in that: The method comprises: A lower electrode (101) and a piezoelectric layer (102) are sequentially arranged on a substrate (100); An upper electrode (103) is arranged on the piezoelectric layer (102); the overlapping portion of the lower electrode (101), the piezoelectric layer (102) and the upper electrode (103) projected on the substrate (100) is an active area; A compensation layer (105) is provided on a substrate (100) on which a piezoelectric layer (102) is formed, and an edge position of the compensation layer (105) corresponding to a projection of the active area is hollowed out to form a hollow groove; A passivation layer (104) is disposed on the compensation layer (105), so that the passivation layer (104) collapses at a position covering the hollow groove to form a groove (106).

10. The method for preparing a thin film bulk acoustic wave resonator according to claim 9, characterized in that: The upper electrode (103) is provided on the piezoelectric layer (102), comprising: Sequentially forming a first upper electrode (107) and a second upper electrode (108) on the upper surface of the piezoelectric layer (102); The method of providing a compensation layer (105) on a substrate (100) having a piezoelectric layer (102) formed thereon comprises: A compensation layer (105) is arranged on the surface of the first upper electrode (107), so that the second upper electrode (108) is laid on the upper surface of the compensation layer (105).

11. The method for preparing a thin film bulk acoustic wave resonator according to claim 9, characterized in that: Before arranging an upper electrode (103) on the piezoelectric layer (102), the method comprises: forming a first sacrificial layer and a second sacrificial layer on opposite sides of the active area on the piezoelectric layer (102); forming a thickening layer (109) on the first sacrificial layer and the second sacrificial layer; After a passivation layer (104) is provided on the compensation layer (105), the method comprises: The first sacrificial layer and the second sacrificial layer are released to form an air wing (110) and an air bridge (111) between the thickened layer (109) and the piezoelectric layer (102).

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