Method and device for improving Q value of bulk acoustic wave resonator

Abstract

The invention relates to the technical field of integrated circuit manufacturing, and particularly discloses a method and device for improving the Q value of a bulk acoustic wave resonator, and the method comprises the steps: respectively generating a bottom electrode and a dielectric layer of the resonator on a substrate, and respectively defining the regions where the bottom electrode and the dielectric layer are located into a resonant region and a non-resonant region; generating a piezoelectric layer lattice regulation and control layer in the non-resonance area; and a piezoelectric layer and a top electrode of the resonator are sequentially generated on the piezoelectric layer crystal lattice regulation and control layer and the bottom electrode. Before the piezoelectric layer is grown in the non-resonant region, a layer of material which is mismatched with the lattice of the piezoelectric layer is grown, and when the piezoelectric layer is grown on substrate materials with different crystal orientations, atoms on two sides of an interface cannot realize an ideal one-to-one pairing state, so that the characteristic of relatively large lattice mismatch is easily formed; therefore, the crystal orientation of the piezoelectric layer in the non-resonance area can be regulated and controlled, and the Q value of the resonator is improved.

Description

Technical Field

[0001] The invention relates to the technical field of integrated circuit manufacturing, and in particular to a method and a device for improving the Q value of a bulk acoustic wave resonator. Background Art

[0002] A bulk acoustic wave resonator is a device that uses the inverse piezoelectric effect of piezoelectric materials to convert electrical energy into mechanical energy and resonate at a specific resonant frequency. The Q value is an important parameter to measure the performance of a resonator. It represents the frequency selection characteristics of the resonator at the resonant frequency. The higher the Q value, the better the frequency selection characteristics of the resonator and the smaller the energy loss.

[0003] In the prior art, the Q value of the resonator is usually improved by improving the structural design of the resonator, optimizing the manufacturing process, etc. For example, by changing the parameters such as the shape and size of the resonant cavity, the resonant characteristics of the resonator can be improved, thereby increasing the Q value.

[0004] In patent applications CN 118264220A and CN 101340181A, the crystal orientation of the non-resonant region is changed by ion implantation, such as Figure 1 As shown; in patent application CN 108231995B, by changing the surface roughness of the substrate in the non-resonant region, such as Figure 2 As shown; in CN 112202415 B, by chemically modifying the substrate surface, such as Figure 3 shown.

[0005] First, due to the complex structure of the resonator, optimizing its structural design often requires a lot of experiments and calculations, which is not only time-consuming and labor-intensive, but may not lead to the optimal solution. Secondly, although the Q value of the resonator can be improved by optimizing the manufacturing process, this often increases production costs and has limited effect on improving the Q value. Existing technologies often ignore the effect of the piezoelectric layer in the non-resonant area on the Q value of the resonator, and the shear wave scattering in this area may cause a large amount of sound wave energy loss, thereby limiting the improvement of the resonator Q value.

[0006] Based on this technical background, the present invention proposes a method and a device for improving the Q value of a bulk acoustic wave resonator. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention proposes a method and device for improving the Q value of a bulk acoustic wave resonator. The method grows a layer of material that is lattice-mismatched with the piezoelectric layer before growing the piezoelectric layer in the non-resonant region. When the piezoelectric layer is grown on a substrate material with different crystal orientations, the atoms on both sides of the interface cannot achieve an ideal one-to-one pairing state, which easily leads to a large lattice mismatch. This can achieve the control of the crystal orientation of the piezoelectric layer in the non-resonant region, thereby improving the Q value of the resonator.

[0008] In order to achieve the above object, the present invention provides a method for improving the Q value of a bulk acoustic wave resonator in a first aspect, comprising:

[0009] Generating a bottom electrode and a dielectric layer of the resonator on the substrate respectively, and defining the areas where the bottom electrode and the dielectric layer are located as resonant areas and non-resonant areas respectively;

[0010] Generating a piezoelectric layer lattice control layer in the non-resonant region;

[0011] The piezoelectric layer and the top electrode of the resonator are sequentially generated on the piezoelectric layer lattice control layer and the bottom electrode.

[0012] A second aspect of the present invention provides a device for improving the Q value of a bulk acoustic wave resonator, comprising:

[0013] substrate;

[0014] A bottom electrode, one surface of which is in contact with a portion of the surface of one side of the substrate, and the area where the other surface is located is a resonance area;

[0015] A dielectric layer, one surface of which is in contact with another surface of one side of the substrate, and the area where the other surface is located is a non-resonant area;

[0016] A piezoelectric layer lattice control layer, one side surface of which is in contact with the surface of the non-resonant region;

[0017] The piezoelectric layer has one side surface in contact with the other side surface of the piezoelectric layer lattice control layer and the surface of the resonance region respectively;

[0018] A top electrode has a surface on one side in contact with the other surface on the piezoelectric layer.

[0019] The technical effects of the present invention include:

[0020] (1) The present invention proposes a method for improving the Q value of a bulk acoustic wave resonator. Before growing the piezoelectric layer in the non-resonant region, a layer of material that is lattice mismatched with the piezoelectric layer is grown. When the piezoelectric layer is grown on a substrate material with different crystal orientations, the atoms on both sides of the interface cannot achieve an ideal one-to-one pairing state, which easily leads to a large lattice mismatch. This allows the crystal orientation of the piezoelectric layer in the non-resonant region to be regulated, thereby improving the Q value of the resonator.

[0021] (2) The present invention proposes a method for improving the Q value of a bulk acoustic wave resonator, which changes the preferred orientation of the piezoelectric layer crystals in the non-resonant region so that the lattice direction of the crystal is mismatched with the direction of sound wave propagation, thereby reducing the shear wave scattering in the non-resonant region, reducing the sound wave energy loss, and improving the Q value of the resonator.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0024] Figure 1 This is a schematic diagram of changing the crystal orientation of the non-resonant region through an ion implantation process in the prior art.

[0025] Figure 2 This is a schematic diagram of the prior art by changing the surface roughness of the substrate in the non-resonant area.

[0026] Figure 3 This is a schematic diagram of the prior art of chemically modifying the substrate surface.

[0027] Figure 4 The present invention is a flow chart of a method for improving the Q value of a bulk acoustic wave resonator.

[0028] Figure 5 The present invention provides a schematic structural diagram of a device for improving the Q value of a bulk acoustic wave resonator.

[0029] Figure 6 A schematic diagram of the diffraction peak intensity of ALN crystals on different substrates in a specific implementation manner of a method for improving the Q value of a bulk acoustic wave resonator proposed by the present invention.

[0030] Figure 7 A schematic diagram of the crystal orientation of ALN crystals grown on MgO substrates with different crystal orientations in a specific implementation of a method for improving the Q value of a bulk acoustic wave resonator proposed by the present invention.

[0031] Description of reference numerals:

[0032] 101 - substrate, 102 - bottom electrode, 103 - piezoelectric layer lattice control layer, 104 - piezoelectric layer, 105 - top electrode, 106 - indentation region, 107 - non-resonant region, 108 - resonant region, 109 - region for suppressing harmonic energy loss in the non-resonant region, 110 - dielectric layer. DETAILED DESCRIPTION

[0033] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0034] In the present invention, unless otherwise specified, the directional words used, such as "upper and lower", generally refer to the upper and lower parts of the device in normal use, and "inside and outside" refer to the outline of the device. In addition, the terms "first, second, third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first, second, third" may explicitly or implicitly include one or more of the features. In the description of the present invention, "multiple" means two or more, unless otherwise clearly and specifically defined.

[0035] The present invention provides a method for improving the Q value of a bulk acoustic wave resonator, such as Figure 4 As shown, including:

[0036] A bottom electrode 102 and a dielectric layer 110 of the resonator are respectively formed on the substrate 101, and the areas where the bottom electrode 102 and the dielectric layer 110 are located are respectively defined as a resonant area 108 and a non-resonant area 107;

[0037] Generating a piezoelectric layer lattice control layer 103 in a non-resonant region 107;

[0038] The piezoelectric layer 104 and the top electrode 105 of the resonator are sequentially generated on the piezoelectric layer lattice control layer 103 and the bottom electrode 102 .

[0039] In the present invention, before growing the piezoelectric layer 104 in the non-resonant region 107, a layer of material that is lattice-mismatched with the piezoelectric layer 104 is grown. When the piezoelectric layer 104 is grown on a substrate 101 material with different crystal orientations, the atoms on both sides of the interface cannot achieve an ideal one-to-one pairing state, which easily leads to a large lattice mismatch. This allows the crystal orientation of the piezoelectric layer 104 in the non-resonant region 107 to be regulated, thereby improving the Q value of the resonator.

[0040] In the present invention, the vertical projection of the piezoelectric layer 104 on the surface of the substrate 101 is contained in the vertical projection of the top electrode 105 on the surface of the substrate 101, that is, the indented area 106 of the top electrode 105 relative to the piezoelectric layer 104. By controlling the size of the indented area 106, the influence of the effective area of ​​the resonant area 108 during the regulation of the crystal orientation of the piezoelectric layer 104 in the non-resonant area 107 can be avoided, thereby improving the Q value of the resonator.

[0041] According to the present invention, it also includes:

[0042] generating a Bragg reflection structure (not shown) or a cavity (not shown) in the substrate 101;

[0043] The vertical projection of the Bragg reflection structure or the cavity on the surface of the substrate 101 is located in the resonance region 108 .

[0044] According to the present invention, the piezoelectric layer lattice control layer 103 is used to change the preferential orientation of the piezoelectric layer 104 crystals in the non-resonant region 107, so that the lattice direction of the piezoelectric layer 104 crystals is mismatched with the sound wave propagation direction, thereby reducing the shear wave scattering in the non-resonant region 107, reducing the sound wave energy loss, and improving the Q value of the resonator.

[0045] According to the present invention, the materials of the bottom electrode 102 and the top electrode 105 are independently selected from one of metal tungsten, molybdenum and aluminum;

[0046] The material of the dielectric layer 110 is silicon dioxide.

[0047] According to the present invention, the material of the piezoelectric layer lattice control layer 103 is aluminum oxide or magnesium oxide.

[0048] Preferably, the thickness of the piezoelectric layer lattice control layer 103 is 1 / 5-1 / 10 of the thickness of the piezoelectric layer 104 .

[0049] According to the present invention, the effective area of ​​the resonance region 108 is the overlapping area formed by vertical projections of the bottom electrode 102 , the piezoelectric layer 104 and the top electrode 105 on the surface of the substrate 101 .

[0050] In the present invention, the preferred orientation of the crystal of the piezoelectric layer 104 in the non-resonant region 107 is changed so that the lattice direction of the crystal is mismatched with the direction of sound wave propagation, thereby reducing the shear wave scattering in the non-resonant region 107, reducing the sound wave energy loss, and improving the Q value of the resonator.

[0051] The present invention provides a device for improving the Q value of a bulk acoustic wave resonator, such as Figure 5 As shown, including:

[0052] Substrate 101;

[0053] The bottom electrode 102 has one side surface in contact with a portion of the surface of one side of the substrate 101 and the other side surface is located in a resonance region 108;

[0054] The dielectric layer 110 has one surface in contact with another surface of one side of the substrate 101 , and the area where the other surface is located is a non-resonant area 107 ;

[0055] The piezoelectric layer lattice control layer 103 has one side surface in contact with the surface of the non-resonant region 107;

[0056] The piezoelectric layer 104 has one side surface in contact with the other side surface of the piezoelectric layer lattice control layer 103 and the surface of the resonance region 108 respectively;

[0057] The top electrode 105 has one surface in contact with the other surface of the piezoelectric layer 104 .

[0058] According to the present invention, a Bragg reflection structure (not shown) is provided in the substrate 101, or a cavity (not shown) is provided in the substrate 101;

[0059] The vertical projection of the Bragg reflection structure or the cavity on the surface of the substrate 101 is located in the resonance region 108 .

[0060] According to the present invention, the thickness of the electric layer lattice control layer is 1 / 5-1 / 10 of the thickness of the piezoelectric layer 104;

[0061] The effective area of ​​the resonance region 108 is the overlapping area formed by vertical projections of the bottom electrode 102 , the piezoelectric layer 104 and the top electrode 105 on the surface of the substrate 101 .

[0062] The present invention will be described in more detail below through specific embodiments.

[0063] Example 1

[0064] like Figure 4 As shown, this embodiment provides a method for improving the Q value of a bulk acoustic wave resonator, comprising:

[0065] A bottom electrode 102 and a dielectric layer 110 of the resonator are respectively formed on the substrate 101, and the areas where the bottom electrode 102 and the dielectric layer 110 are located are respectively defined as a resonant area 108 and a non-resonant area 107;

[0066] Generating a piezoelectric layer lattice control layer 103 in a non-resonant region 107;

[0067] The piezoelectric layer 104 and the top electrode 105 of the resonator are sequentially generated on the piezoelectric layer lattice control layer 103 and the bottom electrode 102;

[0068] In this embodiment, a Bragg reflection structure (not shown) is also generated in the substrate 101 , and the vertical projection of the Bragg reflection structure on the surface of the substrate 101 is located in the resonance region 108 ;

[0069] In this embodiment, in the process of generating the top electrode 105, the size of the indented region 106 of the top electrode 105 relative to the piezoelectric layer 104 is controlled to ensure that the vertical projection of the piezoelectric layer 104 on the surface of the substrate 101 is contained in the vertical projection of the top electrode 105 on the surface of the substrate 101, so as to avoid the influence of the effective region of the resonant region 108 in the process of regulating the crystal orientation of the piezoelectric layer 104 in the non-resonant region 107, thereby improving the Q value of the resonator;

[0070] In this embodiment, the piezoelectric layer lattice control layer 103 is used to change the preferred orientation of the piezoelectric layer 104 crystals in the non-resonant region 107, so that the lattice direction of the piezoelectric layer 104 crystals is mismatched with the sound wave propagation direction, thereby reducing the shear wave scattering in the non-resonant region 107, reducing the sound wave energy loss, and improving the Q value of the resonator;

[0071] In this embodiment, the material of the bottom electrode 102 is metal tungsten, the material of the top electrode 105 is metal molybdenum, the material of the dielectric layer 110 is silicon dioxide, the material of the piezoelectric layer lattice control layer 103 is magnesium oxide, and the thickness of the piezoelectric layer lattice control layer 103 is 1 / 7 of the thickness of the piezoelectric layer 104;

[0072] In this embodiment, the effective area of ​​the resonance region 108 is an overlapping area formed by vertical projections of the bottom electrode 102 , the piezoelectric layer 104 , and the top electrode 105 on the surface of the substrate 101 .

[0073] In this embodiment, before growing the piezoelectric layer (aluminum nitride) in the non-resonant region 107, a layer of material (magnesium oxide) that is lattice-mismatched with the piezoelectric layer is grown; in the filter, the preferred orientation of the aluminum nitride in the piezoelectric layer is the (001) crystal direction, that is, perpendicular to the substrate surface; when aluminum nitride is grown on substrate materials with different crystal orientations, a large lattice mismatch is easily formed because the atoms on both sides of the interface cannot achieve an ideal one-to-one pairing state, thereby achieving the regulation of the crystal orientation of the piezoelectric layer in the non-resonant region 107.

[0074] In this embodiment, by changing the preferred orientation of the crystal of the piezoelectric layer 104 in the non-resonant region 107, the lattice direction of the crystal is mismatched with the propagation direction of the sound wave, thereby reducing the shear wave scattering in the non-resonant region 107, reducing the sound wave energy loss, and improving the Q value of the resonator;

[0075] Figure 6 The diffraction peak intensity of aluminum nitride crystal on different substrates is shown. Figure 7 Shows the crystal orientation of aluminum nitride crystals grown on magnesium oxide substrates with different crystal orientations.

[0076] This embodiment provides a device for improving the Q value of a bulk acoustic wave resonator, such as Figure 5 As shown, including:

[0077] Substrate 101;

[0078] The bottom electrode 102 has one side surface in contact with a portion of the surface of one side of the substrate 101 and the other side surface is located in a resonance region 108;

[0079] The dielectric layer 110 has one surface in contact with another surface of one side of the substrate 101 , and the area where the other surface is located is a non-resonant area 107 ;

[0080] The piezoelectric layer lattice control layer 103 has one side surface in contact with the surface of the non-resonant region 107;

[0081] The piezoelectric layer 104 has one side surface in contact with the other side surface of the piezoelectric layer lattice control layer 103 and the surface of the resonance region 108 respectively;

[0082] A top electrode 105, one surface of which contacts with the other surface of the piezoelectric layer 104;

[0083] In this embodiment, the top electrode 105 has a recessed region 106 relative to the piezoelectric layer 104 , and a Bragg reflection structure (not shown) is provided in the substrate 101 .

[0084] A method for improving the Q value of a bulk acoustic wave resonator proposed in an embodiment of the present invention is to grow a layer of material that is lattice-mismatched with the piezoelectric layer before growing the piezoelectric layer in the non-resonant region. When the piezoelectric layer is grown on a substrate material with different crystal orientations, the atoms on both sides of the interface cannot achieve an ideal one-to-one pairing state, which easily leads to a large lattice mismatch. This can achieve the control of the crystal orientation of the piezoelectric layer in the non-resonant region, thereby improving the Q value of the resonator.

[0085] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for improving the Q value of a bulk acoustic wave resonator, characterized in that: include: Generating a bottom electrode and a dielectric layer of the resonator on the substrate respectively, and defining the areas where the bottom electrode and the dielectric layer are located as resonant areas and non-resonant areas respectively; Generating a piezoelectric layer lattice control layer in the non-resonant region; The piezoelectric layer and the top electrode of the resonator are sequentially generated on the piezoelectric layer lattice control layer and the bottom electrode.

2. The method according to claim 1, characterized in that Also includes: generating a Bragg reflection structure or cavity in the substrate; The Bragg reflection structure or cavity is located in the resonance region in a vertical projection on the surface of the substrate.

3. The method according to claim 1, characterized in that The piezoelectric layer lattice control layer is used to change the preferential orientation of the piezoelectric layer crystals in the non-resonant region, so that the lattice direction of the piezoelectric layer crystals is mismatched with the sound wave propagation direction, thereby reducing the shear wave scattering in the non-resonant region, reducing the sound wave energy loss, and improving the Q value of the resonator.

4. The method according to claim 1, characterized in that The materials of the bottom electrode and the top electrode are independently selected from one of metal tungsten, molybdenum and aluminum; The material of the dielectric layer is silicon dioxide.

5. The method according to claim 1, characterized in that The material of the piezoelectric layer lattice control layer is aluminum oxide or magnesium oxide.

6. The method according to claim 1, characterized in that The thickness of the piezoelectric layer lattice control layer is 1 / 5-1 / 10 of the thickness of the piezoelectric layer.

7. The method according to claim 1, characterized in that The effective area of ​​the resonance region is an overlapping area formed by vertical projections of the bottom electrode, the piezoelectric layer and the top electrode on the surface of the substrate.

8. A device for improving the Q value of a bulk acoustic wave resonator, characterized in that: include: substrate; A bottom electrode, one surface of which is in contact with a portion of the surface of one side of the substrate, and the area where the other surface is located is a resonance area; A dielectric layer, one surface of which is in contact with another surface of one side of the substrate, and the area where the other surface is located is a non-resonant area; A piezoelectric layer lattice control layer, one side surface of which is in contact with the surface of the non-resonant region; The piezoelectric layer has one side surface in contact with the other side surface of the piezoelectric layer lattice control layer and the surface of the resonance region respectively; A top electrode has a surface on one side in contact with the other surface on the piezoelectric layer.

9. The device according to claim 8, characterized in that The substrate is provided with a Bragg reflection structure, or the substrate has a cavity; The Bragg reflection structure or cavity is located in the resonance region in a vertical projection on the surface of the substrate.

10. The device according to claim 8, characterized in that The thickness of the electric layer lattice control layer is 1 / 5-1 / 10 of the thickness of the piezoelectric layer; The effective area of ​​the resonance region is an overlapping area formed by vertical projections of the bottom electrode, the piezoelectric layer and the top electrode on the surface of the substrate.

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