A method for manufacturing a resonator and a resonator

Abstract

The embodiment of the present invention discloses a method for manufacturing a resonator and a resonator. The method includes: a first groove is provided on the first surface of a substrate; a first lower electrode is formed on the first surface of the substrate; the first lower electrode includes an opening, the depth of the opening is equal to the thickness of the first lower electrode, and the vertical projection of the opening on the substrate does not overlap with the first groove; a second lower electrode is formed, and the vertical projection of the first part of the second lower electrode on the substrate coincides with the vertical projection of the opening on the substrate; a second sacrificial layer is formed, the second sacrificial layer only covers the first part, and the thickness of the second sacrificial layer is equal to the depth of the opening; a piezoelectric layer and an upper electrode layer are formed in sequence on the side of the second sacrificial layer away from the substrate; the first sacrificial layer and the second sacrificial layer are processed to form an air bridge between the first part and the piezoelectric layer, and a cavity between the substrate and the lower electrode. The embodiment of the present invention can realize controllable thickness of the air bridge and reduce the difficulty of the manufacturing process of the resonator.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of semiconductor technology, and in particular to a method for manufacturing a resonator and the resonator. Background Art

[0002] Resonators have been widely used in many fields. For example, in the field of wireless communications, resonators of radio frequency (RF) and microwave frequencies are used as filters to improve the reception and transmission of signals. With the need for miniaturization and microminiaturization of communication equipment, resonators based on the piezoelectric effect have been proposed. In a resonator based on the piezoelectric effect, an acoustic resonance mode is generated in a piezoelectric material, in which sound waves are converted into radio waves. One type of piezoelectric resonator is a bulk acoustic resonator (BAW), which has the advantages of small size, high operating frequency, and compatibility with integrated circuit (IC) manufacturing processes. Ideally, a bulk acoustic resonator only excites longitudinal modes in the thickness direction, such as TE modes, which are longitudinal mechanical waves with propagation vectors along the propagation direction. The TE mode ideally propagates along the thickness direction of the piezoelectric layer in the acoustic resonator. However, in addition to the desired TE mode, there are also lateral modes in the acoustic resonator. These lateral modes propagate in the horizontal direction along the surface of the piezoelectric layer. Therefore, the lateral mode adversely affects the quality factor (Q) of the acoustic resonator. At present, an air bridge is usually set in the resonator to suppress the lateral mode.

[0003] In addition, the resonant frequency of the bulk acoustic resonator also changes with temperature. Although the thickness expansion or contraction of each layer of the above-mentioned wave resonator with temperature changes will affect the resonant frequency, the change in the propagation speed of the sound waves in each layer with temperature is the main reason for the change in the resonant frequency of the pressure resonator with temperature. At present, the resonator usually compensates for the influence of temperature changes by setting a temperature compensation structure.

[0004] The thickness of the air bridge and the temperature compensation layer in the resonator are of certain importance to the design. However, the prior art forms the air bridge and / or the temperature compensation layer by etching. Due to process limitations, the thickness of the air bridge and the temperature compensation layer cannot be accurately controlled. Summary of the invention

[0005] The present invention provides a method for manufacturing a resonator and a resonator, so as to achieve controllable thickness of an air bridge and reduce the difficulty of the manufacturing process of the resonator.

[0006] In a first aspect, an embodiment of the present invention provides a method for manufacturing a resonator, comprising:

[0007] Providing a substrate, wherein a first surface of the substrate is provided with a first groove, and the first groove is filled with a first sacrificial layer;

[0008] A first lower electrode is formed on the first surface of the substrate; wherein the first lower electrode comprises an opening, the depth of the opening along the thickness direction of the first lower electrode is equal to the thickness of the first lower electrode, and the vertical projection of the opening on the substrate does not overlap with the first groove;

[0009] forming a second lower electrode on a side of the first lower electrode away from the substrate, the second lower electrode comprising a first portion, a vertical projection of the first portion on the substrate coincident with a vertical projection of the opening on the substrate;

[0010] forming a second sacrificial layer on a side of the second lower electrode away from the substrate, the second sacrificial layer only covers the first portion, and the thickness of the second sacrificial layer is equal to the depth of the opening;

[0011] forming a piezoelectric layer and an upper electrode layer in sequence on a side of the second sacrificial layer away from the substrate, wherein the piezoelectric layer covers the second lower electrode and the second sacrificial layer;

[0012] The first sacrificial layer and the second sacrificial layer are processed to form an air bridge between the first portion and the piezoelectric layer, and a cavity between the substrate and the first lower electrode.

[0013] Optionally, forming a second lower electrode on a side of the first lower electrode away from the substrate further comprises:

[0014] forming a second groove on the second lower electrode, wherein a vertical projection of the second groove on the substrate is located within the first groove;

[0015] Before sequentially forming a piezoelectric layer and an upper electrode layer on a side of the second sacrificial layer away from the substrate, the method further includes:

[0016] A temperature compensation layer is formed on a side of the second lower electrode away from the substrate. The temperature compensation layer is located in the second groove, and a thickness of the temperature compensation layer is equal to a depth of the second groove.

[0017] Optionally, forming a first lower electrode on the first surface of the substrate further comprises:

[0018] forming a third groove on the first lower electrode, wherein a vertical projection of the third groove on the substrate is located within the first groove;

[0019] The second lower electrode further includes a second portion, the second portion being located in the third groove;

[0020] Before sequentially forming a piezoelectric layer and an upper electrode layer on a side of the second sacrificial layer away from the substrate, the method further includes:

[0021] A temperature compensation layer is formed on a side of the second lower electrode away from the substrate, the temperature compensation layer only covers the second portion, and the thickness of the temperature compensation layer is equal to the depth of the third groove.

[0022] Optionally, the depth of the third groove is less than or equal to the depth of the opening.

[0023] Optionally, the first sacrificial layer and / or the second sacrificial layer is a shrinkage material layer; processing the first sacrificial layer and the second sacrificial layer includes: performing annealing on the first sacrificial layer and / or the second sacrificial layer;

[0024] Alternatively, the second sacrificial layer and the temperature compensation layer are made of the same material, and processing the first sacrificial layer and the second sacrificial layer includes: removing the first sacrificial layer and / or the second sacrificial layer by using an etching solution.

[0025] Optionally, the first portion and the second portion of the second lower electrode are formed simultaneously by deposition.

[0026] Optionally, forming a first lower electrode on the first surface of the substrate includes:

[0027] forming a seed layer;

[0028] forming a first electrode material layer;

[0029] The first electrode material layer and the seed layer are patterned in sequence to form the first lower electrode having an opening, or the first electrode material layer is patterned to form the first lower electrode having an opening.

[0030] Optionally, forming a temperature compensation layer on a side of the second lower electrode away from the substrate includes:

[0031] forming a filling layer on a side of the second lower electrode away from the substrate, wherein the filling layer covers the second lower electrode;

[0032] The filling layer is thinned to form the temperature compensation layer.

[0033] Optionally, a chemical mechanical polishing process is used to thin the filling layer.

[0034] Optionally, the material used for the first lower electrode is different from the material used for the second lower electrode;

[0035] The thickness of the first lower electrode ranges from 500 to 3000 Å, and the thickness of the second lower electrode ranges from 1000 to 3000 Å.

[0036] Optionally, the material of the temperature compensation layer includes phosphosilicate glass or silicon dioxide.

[0037] Optionally, a piezoelectric layer and an upper electrode layer are sequentially formed on a side of the second sacrificial layer away from the substrate, comprising:

[0038] A microstructure for reducing the propagation of mechanical waves in the horizontal direction is provided on the upper electrode layer;

[0039] The microstructure includes at least one of a bridge structure, a wing-shaped structure, a protruding structure, and a concave structure.

[0040] In a second aspect, an embodiment of the present invention further provides a resonator, including:

[0041] A substrate, wherein a first surface of the substrate is provided with a first groove;

[0042] A first lower electrode disposed on the first surface of the substrate; wherein the first lower electrode comprises an opening, and a depth of the opening along a thickness direction of the first lower electrode is equal to a thickness of the first lower electrode; and a vertical projection of the opening on the substrate does not overlap with the first groove;

[0043] A second lower electrode is disposed on a side of the first lower electrode away from the substrate, the second lower electrode comprises a first portion, and a vertical projection of the first portion on the substrate coincides with a vertical projection of the opening on the substrate;

[0044] And a piezoelectric layer and an upper electrode layer are arranged on the side of the second lower electrode away from the substrate; wherein the upper electrode layer is arranged on the side of the piezoelectric layer away from the substrate, an air bridge is included between the first part and the piezoelectric layer, and along the thickness direction of the first lower electrode, the thickness of the air bridge is equal to the depth of the first lower electrode.

[0045] Optionally, the second lower electrode comprises a second groove, and a vertical projection of the second groove on the substrate is located inside the first groove;

[0046] The resonator further includes a temperature compensation layer disposed on a side of the second lower electrode away from the substrate. The temperature compensation layer is located in the second groove, and a thickness of the temperature compensation layer is equal to a depth of the second groove.

[0047] Optionally, the first lower electrode comprises a third groove, and a vertical projection of the third groove on the substrate is located within the first groove;

[0048] The second lower electrode comprises a second portion, and the second portion is located in the third groove;

[0049] The resonator further includes a temperature compensation layer disposed on a side of the second lower electrode away from the substrate, the temperature compensation layer only covers the second portion, and a thickness of the temperature compensation layer is equal to a depth of the third groove.

[0050] Optionally, the depth of the third groove is less than or equal to the depth of the opening.

[0051] Optionally, the resonator further includes: a seed layer, wherein the seed layer is located between the first lower electrode and the substrate.

[0052] Optionally, the material used for the first lower electrode is different from the material used for the second lower electrode;

[0053] The thickness of the first lower electrode ranges from 500 to 3000 Å, and the thickness of the second lower electrode ranges from 1000 to 3000 Å.

[0054] Optionally, the material of the temperature compensation layer includes phosphosilicate glass or silicon dioxide.

[0055] Optionally, a microstructure for reducing the propagation of mechanical waves in the horizontal direction is provided on the upper electrode layer;

[0056] The microstructure includes at least one of a bridge structure, a wing-shaped structure, a protruding structure, and a concave structure.

[0057] The resonator of the embodiment of the present invention adopts the form of two layers of lower electrodes, namely, a first lower electrode and a second lower electrode. An opening is set on the first lower electrode so that the surface of the first part of the second lower electrode located in the opening away from the substrate is lower than the surface of the other areas of the second lower electrode other than the first part away from the substrate. The first part is covered with a second sacrificial layer, and the second sacrificial layer on the surface of the first part is processed after forming film layers such as a piezoelectric layer and an upper electrode to form an air bridge between the first part and the piezoelectric layer. The thickness of the air bridge is equal to the thickness of the second sacrificial layer covering the surface of the first part and is equal to the thickness of the first lower electrode or equal to the thickness of the removed second sacrificial layer. Therefore, the thickness of the air bridge can be adjusted by adjusting the thickness of the first lower electrode or by adjusting the thickness of the removed second sacrificial layer. Therefore, the thickness of the air bridge in the resonator provided by this embodiment is controllable, and the formation process is simple, which improves the structural accuracy of the air bridge, improves the compensation effect of the air bridge, and thus improves the quality factor of the resonator. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 is a flow chart of a method for manufacturing a resonator provided by an embodiment of the present invention;

[0059] Figure 2 is a schematic diagram of a first lower electrode provided by an embodiment of the present invention;

[0060] Figure 3 is a schematic diagram of a second lower electrode provided by an embodiment of the present invention;

[0061] Figure 4 is a schematic diagram of a second sacrificial layer provided by an embodiment of the present invention;

[0062] Figure 5 is a schematic diagram of a piezoelectric layer and an upper electrode provided by an embodiment of the present invention;

[0063] Figure 6 is a schematic diagram of a resonator provided by an embodiment of the present invention;

[0064] Figure 7 is a schematic diagram of another lower electrode provided by an embodiment of the present invention;

[0065] Figure 8 is a schematic diagram of another resonator provided by an embodiment of the present invention;

[0066] Fig. 9 is a schematic diagram of another first lower electrode provided by an embodiment of the present invention;

[0067] Fig.10 is a schematic diagram of another second lower electrode provided by an embodiment of the present invention;

[0068] Fig.11 is a schematic diagram of another resonator provided by an embodiment of the present invention;

[0069] Fig.12 is a schematic diagram of a process for forming a temperature compensation material layer provided by an embodiment of the present invention;

[0070] Fig.13 is a schematic diagram of a temperature compensation material layer provided by an embodiment of the present invention;

[0071] Fig.14 is a schematic diagram of another first lower electrode provided by an embodiment of the present invention;

[0072] Fig.15 is a schematic diagram of another resonator provided by an embodiment of the present invention;

[0073] Fig.16 is a schematic diagram of another resonator provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0074] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0075] An embodiment of the present invention provides a method for manufacturing a resonator. Figure 1 is a flow chart of a method for manufacturing a resonator provided by an embodiment of the present invention, with reference to Figure 1 , the method comprising:

[0076] S110, providing a substrate, wherein a first surface of the substrate is provided with a first groove, and the first groove is filled with a first sacrificial layer.

[0077] S120, forming a first lower electrode on the first surface of the substrate; wherein the first lower electrode includes an opening, and the depth of the opening along the thickness direction of the first lower electrode is equal to the thickness of the first lower electrode; the vertical projection of the opening on the substrate does not overlap with the first groove.

[0078] Figure 2 is a schematic diagram of a first lower electrode provided by an embodiment of the present invention, with reference to Figure 2 , a first groove 11 may be formed in the substrate 10 by a photolithography process, and the material of the first sacrificial layer 12 may include phosphosilicate glass (PSG), which schematically includes 8% phosphorus and 92% silicon dioxide. Finally, a cavity may be formed by removing or thinning the first sacrificial layer 12 in the first groove 11. The cavity is used to reflect energy, thereby reducing energy loss and improving the quality factor Q of the resonator. The shape of the first groove 11 can be set as needed, and illustratively, it can be as follows Figure 2 Set the groove to have an inverted trapezoidal cross section.

[0079] The material of the first lower electrode 20 may include molybdenum Mo or tungsten W. When forming the first lower electrode 20, a first material layer may be first formed on the first surface of the substrate 10, and then a photoresist layer may be provided on the surface of the first material layer, and the photoresist layer may be photolithographically processed, and then the first material layer may be etched to form an opening 21, and finally the photoresist layer may be removed. The etching may be dry etching or wet etching, which is not specifically limited in this embodiment. In addition, the shape of the opening 21 is not specifically limited in this embodiment, and may be set according to the shape of the air bridge.

[0080] S130, forming a second lower electrode on a side of the first lower electrode away from the substrate, the second lower electrode comprising a first portion, a vertical projection of the first portion on the substrate coincident with a vertical projection of the opening on the substrate.

[0081] Figure 3 is a schematic diagram of a second lower electrode provided by an embodiment of the present invention, with reference to Figure 3 , located in the opening 21 is the first portion 31 of the second lower electrode 30 .

[0082] S140, forming a second sacrificial layer on a side of the second lower electrode away from the substrate, wherein the second sacrificial layer only covers the first portion, and a thickness of the second sacrificial layer is equal to a depth of the opening.

[0083] Figure 4 is a schematic diagram of a second sacrificial layer provided by an embodiment of the present invention, with reference to Figure 4 The second sacrificial layer 400 covers the first portion 31 of the second lower electrode 30. The thickness of the second sacrificial layer 400 is equal to the depth of the opening 21, and the upper surface of the second sacrificial layer 400 may be flush with the surface of the second lower electrode 30 other than the first portion 31 away from the substrate 10.

[0084] S150, forming a piezoelectric layer and an upper electrode layer in sequence on a side of the second sacrificial layer away from the substrate, wherein the piezoelectric layer covers the second lower electrode and the second sacrificial layer.

[0085] Figure 5 is a schematic diagram of a piezoelectric layer and an upper electrode provided by an embodiment of the present invention, with reference to Figure 5 The thickness uniformity of the piezoelectric layer 50 is required to be less than 1%, so as to ensure that the piezoelectric layer 50 has a high performance. The material used for the upper electrode layer 60 may include Mo or W.

[0086] S160, processing the first sacrificial layer and the second sacrificial layer to form an air bridge between the first portion and the piezoelectric layer, and a cavity between the substrate and the first lower electrode.

[0087] Figure 6 is a schematic diagram of a resonator provided by an embodiment of the present invention, with reference to Figure 6 After the second sacrificial layer covering the first part 31 is removed, there is a gap between the first part 31 and the piezoelectric layer 50, and the gap is the air bridge 80. The air bridge 80 can avoid the energy loss caused by the lateral mode and improve the quality factor Q of the resonator. Processing the first sacrificial layer and the second sacrificial layer may include removing the first sacrificial layer and the second sacrificial layer, or thinning the second sacrificial layer and the first sacrificial layer. For example, after removing the second sacrificial layer, the thickness of the air bridge is equal to the thickness of the second sacrificial layer covering the surface of the first part and is equal to the thickness of the first lower electrode, so the thickness of the air bridge can be adjusted by adjusting the thickness of the first lower electrode, or the second sacrificial layer is thinned, then the thickness of the air bridge is equal to the thickness of the removed second sacrificial layer, and the thickness of the air bridge can be adjusted according to the thickness of the removed second sacrificial layer.

[0088] The resonator of the embodiment of the present invention adopts the form of two layers of lower electrodes, namely, a first lower electrode and a second lower electrode. An opening is set on the first lower electrode so that the surface of the first part of the second lower electrode located in the opening away from the substrate is lower than the surface of the other areas of the second lower electrode other than the first part away from the substrate. The first part is covered with a second sacrificial layer, and the second sacrificial layer on the surface of the first part is processed after forming film layers such as a piezoelectric layer and an upper electrode to form an air bridge between the first part and the piezoelectric layer. The thickness of the air bridge is equal to the thickness of the second sacrificial layer covering the surface of the first part and is equal to the thickness of the first lower electrode or equal to the thickness of the removed second sacrificial layer. Therefore, the thickness of the air bridge can be adjusted by adjusting the thickness of the first lower electrode or by adjusting the thickness of the removed second sacrificial layer. Therefore, the thickness of the air bridge in the resonator provided by this embodiment is controllable, and the formation process is simple, which improves the structural accuracy of the air bridge, improves the compensation effect of the air bridge, and thus improves the quality factor of the resonator.

[0089] Figure 7 is a schematic diagram of another lower electrode provided in an embodiment of the present invention, optionally, refer to Figure 7 ,, forming a second lower electrode 30 on a side of the first lower electrode 20 away from the substrate 10 also includes:

[0090] A second groove 32 is formed on the second lower electrode 30, and a vertical projection of the second groove 32 on the substrate 10 is located inside the first groove 11;

[0091] Figure 8 is a schematic diagram of another resonator provided by an embodiment of the present invention, referring to Figure 8 Optionally, before the piezoelectric layer 50 and the upper electrode layer 60 are sequentially formed on the side of the second sacrificial layer away from the substrate 10, the method further includes:

[0092] A temperature compensation layer 70 is formed on a side of the second lower electrode 30 away from the substrate 10 . The temperature compensation layer 70 is located in the second groove 32 , and the thickness of the temperature compensation layer 70 is equal to the depth of the second groove 32 .

[0093] Specifically, the temperature compensation layer 70 can compensate for the influence of temperature change on the resonator, and the temperature compensation layer 70 can be made of a material with a positive temperature coefficient. The thickness of the temperature compensation layer 70 can be adjusted by adjusting the depth of the second groove 32. Therefore, the thickness of the temperature compensation layer in the resonator provided by this embodiment is controllable, and the formation process is simple, which improves the structural accuracy of the temperature compensation layer, improves the compensation effect of the temperature compensation layer, and thus improves the quality factor of the resonator.

[0094] Fig. 9 is a schematic diagram of another first lower electrode provided by an embodiment of the present invention, Fig.10 is a schematic diagram of another second lower electrode provided by an embodiment of the present invention, referring to Fig. 9 and Fig.10 Optionally, forming the first lower electrode 20 on the first surface of the substrate 10 further includes:

[0095] A third groove 22 is formed on the first lower electrode 20, and a vertical projection of the third groove 22 on the substrate is located inside the first groove 11;

[0096] The second lower electrode 30 further includes a second portion 33 , and the second portion 33 is located in the third groove 22 .

[0097] Fig.11 is a schematic diagram of another resonator provided by an embodiment of the present invention, with reference to Fig.11 Before sequentially forming the piezoelectric layer 50 and the upper electrode layer 60 on the side of the second sacrificial layer away from the substrate 10, the method further includes:

[0098] A temperature compensation layer 70 is formed on a side of the second lower electrode 30 away from the substrate 10 . The temperature compensation layer 70 only covers the second portion 33 , and the thickness of the temperature compensation layer 70 is equal to the depth of the third groove 22 .

[0099] Specifically, the opening 21 and the third groove 22 can be etched simultaneously. The depth of the third groove 22 can be the same as the depth of the opening 21, that is, both are equal to the thickness of the first lower electrode 20. The depth of the third groove 22 can also be different from the depth of the opening 21. The specific depth of the third groove 22 can be set according to the thickness of the temperature compensation layer 70. The opening 21 is used to form an air bridge 80, and the third groove 22 is used to form a temperature compensation layer 70. In this embodiment, two layers of lower electrodes, namely, a first lower electrode 20 and a second lower electrode 30, are provided. The opening 21 and the third groove 22 are formed by etching the first lower electrode 20, so that after the second lower electrode 30 is subsequently formed, the surface of the second lower electrode 30 corresponding to the opening 21 and the second portion 33 corresponding to the third groove 22 away from the substrate 10 has a height difference with the surface of the other regions of the second lower electrode 30 away from the substrate 10. Subsequently, film layers such as a temperature compensation layer 70, a piezoelectric layer 50 and an upper electrode layer 60 are formed, and the second sacrificial layer on the surface of the first portion 31 is processed. After the air bridge 80 and the temperature compensation layer 70 are formed, the thickness of the air bridge 80 is equal to the thickness of the removed second sacrificial layer, and the thickness of the temperature compensation layer 70 is equal to the depth of the third groove 22. The thickness of the air bridge 80 and the thickness of the temperature compensation layer 70 can be adjusted by adjusting the thickness of the removed second sacrificial layer and the thickness of the third groove 22, so that the thickness of the air bridge 80 and the temperature compensation layer 70 are adjustable.

[0100] Exemplarily, when the second sacrificial layer is removed, the thickness of the air bridge 80 is equal to the depth of the opening 21, which is equal to the thickness of the first lower electrode 20, and the thickness of the temperature compensation layer 70 is equal to the depth of the third groove 22. The thickness of the air bridge 80 and the thickness of the temperature compensation layer 70 can be adjusted by adjusting the thickness of the first lower electrode 20 and the depth of the third groove 22, thereby achieving adjustable thickness of the air bridge 80 and the temperature compensation layer 70, and the implementation method is simple, the process is simple, and the process cost is reduced.

[0101] Optionally, the depth of the third groove 22 is less than or equal to the depth of the opening 21 .

[0102] Specifically, the depth of the third groove 22 can be set according to the thickness of the temperature compensation layer 70 , which is not specifically limited in this embodiment.

[0103] Optionally, the depth of the third groove 22 is equal to the depth of the opening 21, that is, the depth of the third groove 22 is equal to the thickness of the first lower electrode 20, and the thickness of the air bridge 80 is equal to the thickness of the temperature compensation layer 70. In this embodiment, the thickness of the air bridge 80 and the temperature compensation layer 70 can be adjusted by adjusting the thickness of the first lower electrode 20, and the depth of the third groove 22 and the opening 21 are the same, and the third groove 22 and the opening 21 can be formed simultaneously by a photolithography process, which reduces the process difficulty.

[0104] Optionally, the first sacrificial layer and / or the second sacrificial layer is a shrinkage material layer; and processing the first sacrificial layer and the second sacrificial layer includes: performing annealing treatment on the first sacrificial layer and / or the second sacrificial layer.

[0105] Specifically, the shrinkage material refers to a material that has shrinkage under specific conditions. The shrinkage material can be a porous loose material, such as amorphous silicon or low-temperature SiN (i.e. SiN with a growth temperature of 300°C to 500°C). In addition, the shrinkage material can also be a material containing volatile substances, such as SiO2 containing water vapor (which can be achieved by adjusting the hydrogen content during the growth of SiO2).

[0106] The treatment of the first sacrificial layer and the second sacrificial layer may be a high temperature treatment, and the high temperature treatment is preferably an annealing operation, wherein the annealing operation may be furnace annealing, spike annealing, laser annealing or flash annealing. If the high temperature annealing is furnace annealing, the annealing temperature range is 300°C to 1100°C, and the annealing time is generally not more than 10 hours, such as 3 hours, 5 hours, 8 hours, etc. If the high temperature treatment is spike annealing, the annealing temperature range is 650°C to 1300°C, and the annealing time is generally not more than 20 seconds, such as 5 seconds, 10 seconds, 15 seconds, etc. If the high temperature treatment is laser annealing or flash annealing, the annealing temperature range is 700°C to 1500°C, and the annealing time is generally not more than 20 milliseconds, such as 5 milliseconds, 10 milliseconds, 15 milliseconds, etc. In particular, when the shrink material layer is treated by a second-level or even millisecond-level annealing process, the time for forming the air gap can be greatly shortened, thereby greatly improving the production efficiency. It can be understood by those skilled in the art that the annealing operation is only a preferred embodiment, and in other embodiments, other high-temperature treatments that can cause the shrink material layer to shrink in volume are also applicable to the present invention.

[0107] Optionally, the second sacrificial layer and the temperature compensation layer are made of the same material, and processing the first sacrificial layer and the second sacrificial layer includes: removing the first sacrificial layer and / or the second sacrificial layer by using an etching solution.

[0108] Specifically, the first sacrificial layer and the second sacrificial layer can be removed by using a solution such as hydrogen fluoride. The thickness of the air bridge 80 formed after removing the second sacrificial layer is equal to the depth of the opening 21, that is, equal to the thickness of the first lower electrode 20. The thickness of the air bridge 80 and the thickness of the temperature compensation layer 70 can be adjusted by adjusting the thickness of the first lower electrode 20. The implementation method is simple, the process is simple, and the process cost is reduced.

[0109] Optionally, the first portion and the second portion of the second lower electrode are formed simultaneously by deposition.

[0110] Specifically, a whole layer of the second lower electrode with uniform thickness may be deposited on the surface of the first lower electrode, and the uniformity of the second lower electrode is required to be less than 1%.

[0111] Fig.12 is a schematic diagram of a process for forming a temperature compensation material layer provided by an embodiment of the present invention, Fig.13 is a schematic diagram of a temperature compensation material layer provided by an embodiment of the present invention, with reference to Fig.12 and Fig.13Optionally, forming a temperature compensation layer on the side of the second lower electrode 30 away from the substrate 10 includes: forming a filling layer 41 on the side of the second lower electrode 30 away from the substrate 10, the filling layer 41 covering the second lower electrode 30; thinning the filling layer 41 to form a temperature compensation layer.

[0112] Among them, the thickness of the filling layer 41 can include 2000A-20000A, and the uniformity requirement is less than 5%, so that when the filling layer 41 is thinned, a long thinning time is not required, the process time is shortened, and the temperature compensation layer formed after thinning is ensured to have a higher surface flatness.

[0113] In addition, when the second sacrificial layer and the temperature compensation layer are made of the same material, the second sacrificial layer can be made together with the temperature compensation layer. The specific process is that a filling layer can be set to cover the entire surface of the second lower electrode 30 away from the substrate 10, and the filling layer 41 covered by the first part 31 is retained when the filling layer 41 is thinned. After the piezoelectric layer and the upper electrode are formed, the filling layer 41 covering the first part 31 is removed. At this time, the filling layer 41 requires a 10% hydrogen fluoride solution The etching rate is greater than 10000A / min, so as to ensure that the subsequent removal of the filling layer 41 on the surface of the first part 31 has a faster removal rate, thereby improving the manufacturing efficiency of the resonator.

[0114] Fig.14 is a schematic diagram of another first lower electrode provided by an embodiment of the present invention. Optionally, a first lower electrode 20 is formed on the first surface of the substrate 10, including:

[0115] forming a seed layer 210;

[0116] forming a first electrode material layer;

[0117] The first electrode material layer and the seed layer 210 are patterned in sequence to form the first lower electrode 20 having the opening 21 , or the first electrode material layer is patterned to form the first lower electrode 20 having the opening 21 .

[0118] Specifically, the material of the seed layer 210 may be aluminum nitride or the like, and the material of the first electrode material layer may be Mo or W, exemplarily Mo. After forming the seed layer 210 and the first electrode material layer, a photoresist layer may be formed on the surface of the first electrode material layer, the photoresist layer may be patterned by a photolithography process, and then the first electrode material layer and the seed layer 210 may be etched in sequence. The first electrode material layer and the seed layer 210 may be etched by wet etching or dry etching.

[0119] It should be noted that when the seed layer 210 is also etched through, that is, when the opening 21 passes through the seed layer 210 , the thickness of the air bridge is equal to the sum of the thickness of the first lower electrode 20 and the thickness of the seed layer 210 .

[0120] Optionally, a chemical mechanical polishing process is used to thin the filling layer.

[0121] Specifically, since the process controllability of the chemical mechanical polishing (CMP) process is relatively high and the polishing precision is high, the filling layer is thinned by using the chemical mechanical polishing process, so that the height difference between the surface of the formed temperature compensation layer away from the substrate and the surface of the second lower electrode other than the first part and the second part away from the substrate is small, so that the surface of the temperature compensation layer and the second lower electrode away from the substrate is flush, ensuring that the piezoelectric layer formed subsequently has a high thickness uniformity. In addition, the chemical mechanical polishing process causes less damage to the surface of the second lower electrode. For example, when the second lower electrode is made of Mo material, the damage to Mo can be less than 20A.

[0122] Optionally, the material used for the first lower electrode is different from the material used for the second lower electrode;

[0123] The thickness of the first lower electrode ranges from 500 to 3000 Å, and the thickness of the second lower electrode ranges from 1000 to 3000 Å.

[0124] Specifically, the second lower electrode and the second lower electrode are made of different materials to ensure that the formation process of the second lower electrode has little effect on the formation process of the first lower electrode, avoiding the influence on the structure of the first lower electrode when the second lower electrode is formed. In addition, the thickness range of the first lower electrode includes 500-3000A, so that the formed air bridge and temperature compensation layer have a good compensation effect. In addition, the thickness of the second lower electrode can be set as needed, and can be 1500A, 1700A or 1800A, etc., which is not specifically limited in this embodiment.

[0125] Optionally, the material of the temperature compensation layer includes phosphosilicate glass or silicon dioxide.

[0126] Specifically, using the above-mentioned material to form a temperature compensation layer can, on the one hand, better perform temperature compensation on the resonator; on the other hand, the manufacturing process of the above-mentioned material is easier to control and easier to remove, so that the temperature compensation material layer on the surface of the first part can be removed faster without affecting the second lower electrode and the piezoelectric layer.

[0127] Fig.15 is a schematic diagram of another resonator provided by an embodiment of the present invention, Fig.16 is a schematic diagram of another resonator provided in an embodiment of the present invention, optionally, refer to Fig.15 and Fig.16 , a piezoelectric layer 50 and an upper electrode layer 60 are sequentially formed on a side of the second sacrificial layer away from the substrate, including:

[0128] A microstructure 61 for reducing the propagation of mechanical waves in the horizontal direction is provided on the upper electrode layer 60;

[0129] The microstructure 61 includes at least one of a bridge structure, a wing-shaped structure, a protrusion structure, and a concave structure.

[0130] Specifically, the microstructure 61 may include: Fig.16 The bridge structure shown, Fig.15 This embodiment does not specifically limit any one or more of the wing-shaped structure, protruding structure and recessed structure shown.

[0131] This embodiment also provides a resonator, referring to Figure 6 , the resonator includes:

[0132] A substrate 10, wherein a first surface of the substrate 10 is provided with a first groove 11;

[0133] A first lower electrode 20 is disposed on the first surface of the substrate 10; wherein the first lower electrode 20 includes an opening 21, and the depth of the opening 21 along the thickness direction of the first lower electrode 20 is equal to the thickness of the first lower electrode 20; and the vertical projection of the opening 21 on the substrate 10 does not overlap with the first groove 11;

[0134] A second lower electrode 30 is disposed on a side of the first lower electrode 20 away from the substrate 10 , the second lower electrode 30 includes a first portion 31 , and a vertical projection of the first portion 31 on the substrate 10 coincides with a vertical projection of the opening 21 on the substrate 10 ;

[0135] And a piezoelectric layer 50 and an upper electrode layer 60 are arranged on the side of the second lower electrode 30 away from the substrate 10; wherein the upper electrode layer 60 is arranged on the side of the piezoelectric layer 50 away from the substrate 10, and an air bridge 80 is included between the first part 31 and the piezoelectric layer 50, and along the thickness direction of the first lower electrode 20, the thickness of the air bridge 80 is equal to the depth of the first lower electrode 20.

[0136] Optional, reference Figure 8 The second lower electrode 30 includes a second groove 32, and the vertical projection of the second groove 32 on the substrate 10 is located in the first groove 11;

[0137] The resonator further includes a temperature compensation layer 70 disposed on a side of the second lower electrode 30 away from the substrate 10 . The temperature compensation layer 70 is located in the second groove 32 , and the thickness of the temperature compensation layer 70 is equal to the depth of the second groove 32 .

[0138] Optional, reference Fig.11 , the first lower electrode 20 includes a third groove 22, and the vertical projection of the third groove 22 on the substrate 10 is located in the first groove 11;

[0139] The second lower electrode 30 includes a second portion 33 , and the second portion 33 is located in the third groove 22 ;

[0140] The resonator further includes a temperature compensation layer 70 disposed on a side of the second lower electrode 30 away from the substrate 10 . The temperature compensation layer 70 only covers the second portion 33 , and the thickness of the temperature compensation layer 70 is equal to the depth of the third groove 22 .

[0141] Optionally, the depth of the third groove 22 is less than or equal to the depth of the opening 21 .

[0142] Optional, reference Fig.14 The resonator further includes: a seed layer 210 , and the seed layer 210 is located between the first lower electrode 20 and the substrate 10 .

[0143] Optionally, the material used for the first lower electrode is different from the material used for the second lower electrode;

[0144] The thickness of the first lower electrode ranges from 500 to 3000 Å, and the thickness of the second lower electrode ranges from 1000 to 3000 Å.

[0145] Optionally, the material of the temperature compensation layer includes phosphosilicate glass or silicon dioxide.

[0146] refer to Fig.14 and Fig.15 , Optionally, a microstructure 61 for reducing the propagation of mechanical waves in the horizontal direction is provided on the upper electrode layer 60;

[0147] The microstructure 61 includes at least one of a bridge structure, a wing-shaped structure, a protrusion structure, and a concave structure.

[0148] The resonator provided in this embodiment and the method for manufacturing the resonator provided in any embodiment of the present invention belong to the same inventive concept and have corresponding beneficial effects. For technical details not detailed in this embodiment, please refer to the method for manufacturing the resonator provided in any embodiment of the present invention.

[0149] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for manufacturing a resonator, characterized in that: include: Providing a substrate, wherein a first surface of the substrate is provided with a first groove, and the first groove is filled with a first sacrificial layer; A first lower electrode is formed on the first surface of the substrate; wherein the first lower electrode comprises an opening, the depth of the opening along the thickness direction of the first lower electrode is equal to the thickness of the first lower electrode, and the vertical projection of the opening on the substrate does not overlap with the first groove; forming a second lower electrode on a side of the first lower electrode away from the substrate, the second lower electrode comprising a first portion, a vertical projection of the first portion on the substrate coincident with a vertical projection of the opening on the substrate; forming a second sacrificial layer on a side of the second lower electrode away from the substrate, the second sacrificial layer only covers the first portion, and the thickness of the second sacrificial layer is equal to the depth of the opening; forming a piezoelectric layer and an upper electrode layer in sequence on a side of the second sacrificial layer away from the substrate, wherein the piezoelectric layer covers the second lower electrode and the second sacrificial layer; The first sacrificial layer and the second sacrificial layer are processed to form an air bridge between the first portion and the piezoelectric layer, and a cavity between the substrate and the first lower electrode.

2. The method according to claim 1, characterized in that: Forming a second lower electrode on a side of the first lower electrode away from the substrate further comprises: forming a second groove on the second lower electrode, wherein a vertical projection of the second groove on the substrate is located within the first groove; Before sequentially forming a piezoelectric layer and an upper electrode layer on a side of the second sacrificial layer away from the substrate, the method further includes: A temperature compensation layer is formed on a side of the second lower electrode away from the substrate. The temperature compensation layer is located in the second groove, and a thickness of the temperature compensation layer is equal to a depth of the second groove.

3. The method according to claim 1, characterized in that: Forming a first lower electrode on the first surface of the substrate further comprises: forming a third groove on the first lower electrode, wherein a vertical projection of the third groove on the substrate is located within the first groove; The second lower electrode further includes a second portion, the second portion being located in the third groove; Before sequentially forming a piezoelectric layer and an upper electrode layer on a side of the second sacrificial layer away from the substrate, the method further includes: A temperature compensation layer is formed on a side of the second lower electrode away from the substrate, the temperature compensation layer only covers the second portion, and the thickness of the temperature compensation layer is equal to the depth of the third groove.

4. The method according to claim 3, characterized in that: The depth of the third groove is less than or equal to the depth of the opening.

5. The method according to claim 2 or 3, characterized in that: The first sacrificial layer and / or the second sacrificial layer is a shrinkage material layer; Processing the first sacrificial layer and the second sacrificial layer includes: performing annealing on the first sacrificial layer and / or the second sacrificial layer; Alternatively, the second sacrificial layer and the temperature compensation layer are made of the same material, and processing the first sacrificial layer and the second sacrificial layer includes: removing the first sacrificial layer and / or the second sacrificial layer by using an etching solution.

6. The method according to claim 3, characterized in that: The second lower electrode is formed by depositing the first part and the second part at the same time.

7. The method according to claim 1, characterized in that A first lower electrode is formed on the first surface of the substrate, comprising: forming a seed layer; forming a first electrode material layer; The first electrode material layer and the seed layer are patterned in sequence to form the first lower electrode having an opening, or the first electrode material layer is patterned to form the first lower electrode having an opening.

8. The method according to claim 2 or 3, characterized in that: Forming a temperature compensation layer on a side of the second lower electrode away from the substrate comprises: forming a filling layer on a side of the second lower electrode away from the substrate, wherein the filling layer covers the second lower electrode; The filling layer is thinned to form the temperature compensation layer.

9. The method according to claim 8, characterized in that The filling layer is thinned by a chemical mechanical polishing process.

10. The method according to claim 1, characterized in that: The material used for the first lower electrode is different from the material used for the second lower electrode; The thickness of the first lower electrode ranges from 500 to 3000 Å, and the thickness of the second lower electrode ranges from 1000 to 3000 Å.

11. The method according to claim 2 or 3, characterized in that: The material of the temperature compensation layer includes phosphosilicate glass or silicon dioxide.

12. The method according to claim 1, characterized in that A piezoelectric layer and an upper electrode layer are sequentially formed on a side of the second sacrificial layer away from the substrate, comprising: A microstructure for reducing the propagation of mechanical waves in the horizontal direction is provided on the upper electrode layer; The microstructure includes at least one of a bridge structure, a wing-shaped structure, a protruding structure, and a concave structure.

13. A resonator, characterized in that: include: A substrate, wherein a first surface of the substrate is provided with a first groove; A first lower electrode disposed on the first surface of the substrate; wherein the first lower electrode comprises an opening, and a depth of the opening along a thickness direction of the first lower electrode is equal to a thickness of the first lower electrode; and a vertical projection of the opening on the substrate does not overlap with the first groove; A second lower electrode is disposed on a side of the first lower electrode away from the substrate, the second lower electrode comprises a first portion, and a vertical projection of the first portion on the substrate coincides with a vertical projection of the opening on the substrate; And a piezoelectric layer and an upper electrode layer are arranged on the side of the second lower electrode away from the substrate; wherein the upper electrode layer is arranged on the side of the piezoelectric layer away from the substrate, an air bridge is included between the first part and the piezoelectric layer, and along the thickness direction of the first lower electrode, the thickness of the air bridge is equal to the depth of the first lower electrode.

14. The resonator according to claim 13, characterized in that: The second lower electrode comprises a second groove, and a vertical projection of the second groove on the substrate is located inside the first groove; The resonator further includes a temperature compensation layer disposed on a side of the second lower electrode away from the substrate. The temperature compensation layer is located in the second groove, and a thickness of the temperature compensation layer is equal to a depth of the second groove.

15. The resonator according to claim 13, characterized in that: The first lower electrode comprises a third groove, and the vertical projection of the third groove on the substrate is located inside the first groove; The second lower electrode includes a second portion, and the second portion is located in the third groove; The resonator further includes a temperature compensation layer disposed on a side of the second lower electrode away from the substrate, the temperature compensation layer only covers the second portion, and a thickness of the temperature compensation layer is equal to a depth of the third groove.

16. The resonator according to claim 15, characterized in that: The depth of the third groove is less than or equal to the depth of the opening.

17. The resonator according to claim 13, characterized in that Also includes: A seed layer is located between the first lower electrode and the substrate.

18. The resonator according to claim 13, characterized in that: The material used for the first lower electrode is different from the material used for the second lower electrode; The thickness of the first lower electrode ranges from 500 to 3000 Å, and the thickness of the second lower electrode ranges from 1000 to 3000 Å.

19. The resonator according to claim 14 or 15, characterized in that: The material of the temperature compensation layer includes phosphosilicate glass or silicon dioxide.

20. The resonator according to claim 13, characterized in that: The upper electrode layer is provided with a microstructure for reducing the propagation of mechanical waves in the horizontal direction; The microstructure includes at least one of a bridge structure, a wing-shaped structure, a protruding structure, and a concave structure.

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