Elastic wave device and module

Abstract

The utility model relates to an elastic wave device and module, the elastic wave device comprises a piezoelectric substrate, a piezoelectric layer and an IDT electrode, the IDT electrode is formed on the main surface of the piezoelectric layer and is used for exciting an elastic wave with the wavelength of lambda; the piezoelectric layer is laminated on the piezoelectric substrate; wherein the piezoelectric layer is made of lithium niobate; the cutting angle of the piezoelectric layer is different from the cutting angle of the piezoelectric substrate; the cutting angle of the piezoelectric layer is a Y-direction cutting X-direction propagation angle of-20 degrees to 20 degrees or 150 degrees to 210 degrees; the thickness ratio of the piezoelectric layer to the piezoelectric substrate is smaller than 0.1, the elastic wave device solves the problem that a large-bandwidth SAW filter in the prior art is large in clutter, and the insertion loss of the high end of a passband of the filter is effectively reduced.

Description

TECHNICAL FIELD

[0001] The utility model relates to the technical field of semiconductor packaging, especially to an elastic wave device and module. BACKGROUND

[0002] With the continuous development of radio frequency communication technology, the requirements for bandwidth and quality factor of the filter are also increasing, and the surface acoustic wave resonator based on the surface acoustic wave (Surface Acoustic Wave, SAW) technology is widely used in filter design due to its high quality factor, low cost, and small size.

[0003] The traditional SAW resonator is composed of a piezoelectric substrate, a piezoelectric layer stacked on the piezoelectric substrate, and an IDT electrode (Interdigital Transducer) disposed on the main surface of the piezoelectric layer. The piezoelectric layer usually uses lithium tantalate, lithium niobate, quartz, and other piezoelectric materials. Lithium niobate is widely used in large-bandwidth surface acoustic wave filters due to its high electromechanical coupling coefficient. However, the surface acoustic wave resonator with lithium niobate as the piezoelectric material often has Rayleigh wave and other in-band spurs in the passband, affecting the insertion loss and flatness of the filter passband. At the same time, body wave leakage occurs on the high side of the resonator, resulting in a decrease in the quality factor and affecting the insertion loss of the high end of the filter passband.

[0004] There is currently no suitable solution to the problem of large spurs in large-bandwidth SAW filters in the prior art. SUMMARY

[0005] The utility model provides a kind of elastic wave device and module to solve the problem of large spurs in large-bandwidth SAW filters in the prior art.

[0006] In the first aspect, an elastic wave device is provided in this embodiment, comprising a piezoelectric substrate, a piezoelectric layer, and an IDT electrode,

[0007] The IDT electrode is formed on the main surface of the piezoelectric layer and is used to excite elastic waves with a wavelength of λ;

[0008] The piezoelectric layer is stacked on the piezoelectric substrate;

[0009] The piezoelectric layer is made of lithium niobate, the cut angle of the piezoelectric layer is different from the cut angle of the piezoelectric substrate, the cut angle of the piezoelectric layer is -20° to 20° or 150° to 210° along the Y direction, and the thickness ratio of the piezoelectric layer to the piezoelectric substrate is less than 0.1.

[0010] In some embodiments, the piezoelectric layer includes a first piezoelectric layer and a second piezoelectric layer, the first piezoelectric layer is stacked on the second piezoelectric layer.

[0011] The cut angle of the first piezoelectric layer, the cut angle of the second piezoelectric layer, and the cut angle of the piezoelectric substrate are all different.

[0012] In some embodiments, the piezoelectric substrate includes a first piezoelectric substrate and a second piezoelectric substrate, the first piezoelectric substrate is stacked on the second piezoelectric substrate.

[0013] The cut angle of the piezoelectric layer, the cut angle of the first piezoelectric substrate, and the cut angle of the second piezoelectric substrate are all different.

[0014] In some embodiments, the material of the piezoelectric substrate includes lithium tantalate, lithium niobate, or quartz.

[0015] In some embodiments, the thickness of the piezoelectric layer is 0.1λ-0.4λ.

[0016] In some embodiments, an adhesive layer is further included between the piezoelectric layer and the piezoelectric substrate, and the material of the adhesive layer includes at least one of silicon, titanium, nickel, chromium, or tungsten.

[0017] In some embodiments, a temperature compensation layer is further included between the piezoelectric layer and the piezoelectric substrate.

[0018] In some embodiments, a high acoustic velocity layer and a low acoustic velocity layer are further included between the piezoelectric layer and the piezoelectric substrate.

[0019] In some embodiments, the material of the high acoustic velocity layer includes silicon carbide or silicon nitride, and the material of the low acoustic velocity layer is silicon oxide.

[0020] In a second aspect, the utility model provides a module, including the elastic wave device of above -mentioned first aspect.

[0021] Compared with the related art, the elastic wave device and the module are provided in the embodiment, including a piezoelectric substrate, a piezoelectric layer, and an IDT electrode, the IDT electrode is formed on the main surface of the piezoelectric layer, and is used to excite an elastic wave with a wavelength of λ;The piezoelectric layer is stacked on the piezoelectric substrate;Wherein, the cut angle of the piezoelectric layer is different from the cut angle of the piezoelectric substrate;The material of the piezoelectric layer is lithium niobate;The cut angle of the piezoelectric layer is-20°-20° along the Y direction or 150°-210° along the X direction;The thickness ratio of the piezoelectric layer and the piezoelectric substrate is less than 0.1.Through the above-mentioned elastic wave device, the problem of large SAW filter clutter in the prior art is solved, and the insertion loss of the high end of the filter passband is effectively reduced.

[0022] The details of one or more embodiments of the application are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the application will be apparent from the description of the embodiments and from the drawings, and variations thereof. BRIEF DESCRIPTION OF DRAWINGS

[0023] The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiments of the application and together with the description serve to explain the application. In the drawings:

[0024] Figure 1 is a cross-sectional view of an elastic wave device of a first embodiment of the present application;

[0025] Figure 2 is a frequency-admittance characteristic diagram of the elastic wave device of the first embodiment of the present application with respect to the thickness of the piezoelectric layer;

[0026] Figure 3 is a characteristic diagram of the electromechanical coupling coefficient of the elastic wave device of the present application with respect to the cut angle of the piezoelectric layer;

[0027] Figure 4 is a frequency-admittance characteristic diagram of the elastic wave device of the first embodiment and a comparative example;

[0028] Figure 5 is a cross-sectional view of an elastic wave device of a second embodiment of the present application;

[0029] Figure 6 is a cross-sectional view of an elastic wave device of a third embodiment of the present application;

[0030] Figure 7 is a cross-sectional view of an elastic wave device of a fourth embodiment of the present application;

[0031] Figure 8 is a cross-sectional view of an elastic wave device of a fifth embodiment of the present application;

[0032] Figure 9 is a cross-sectional view of an elastic wave device of a sixth embodiment of the present application;

[0033] Figure 10 is a cross-sectional view of an elastic wave device of a preferred embodiment of the present application;

[0034] Figure 11 is a cross-sectional view of a module of an elastic wave device of an embodiment of the present application.

[0035] In the figure: 100, piezoelectric substrate; 110, first piezoelectric substrate; 120, second piezoelectric substrate; 200, piezoelectric layer; 210, first piezoelectric layer; 220, second piezoelectric layer; 300, IDT electrode; 400, adhesion layer; 500, temperature compensation layer; 510, low acoustic velocity layer; 520, high acoustic velocity layer; 610, metal bump; 620, columnar metal; 630, seed layer; 700, protective layer; 600, elastic wave device; 700, inductor; 800, wiring substrate; 900, sealing portion; 801, IC integrated circuit component; 802, connection terminal. DETAILED DESCRIPTION

[0036] For the purpose of more clearly understanding the purpose, technical solutions and advantages of the present application, the present application is described and explained below in connection with the drawings and embodiments.

[0037] Unless otherwise defined, technical terms or scientific terms used in the present application shall have the general meaning understood by a person with ordinary skill in the art to which the present application belongs. In the present application, "one", "a", "an", "the", "these" and similar words do not represent a quantitative limitation, and they can be singular or plural. In the present application, the terms "include", "contain", "have" and any variants thereof have the purpose of covering non-exclusive inclusion; for example, a process, method and system, product or device containing a series of steps or modules (units) are not limited to the listed steps or modules (units), but can include steps or modules (units) not listed, or can include other steps or modules (units) inherent to the process, method, product or device. In the present application, the terms "connected", "connected", "coupled" and similar words are not limited to physical or mechanical connections, but can include electrical connections, whether direct or indirect. In the present application, "multiple" means two or more. The association between the associated objects is described by "and / or", which means that there can be three relationships, for example, "A and / or B" can mean that A exists alone, A and B exist together, and B exists alone. In general, the character " / " represents an "or" relationship between the associated objects. In the present application, the terms "first", "second", "third" and the like are only used to distinguish similar objects, and do not represent a specific order of the objects.

[0038] In the following, based on Figures 1 to 11 The elastic wave device of the present application is described.

[0039] The embodiments are described below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals. For parts that are repeatedly described, appropriate simplification or omission will be made.

[0040] Figure 1This is a cross-sectional view of the elastic wave device according to the first embodiment of this application, as shown below. Figure 1 As shown, the elastic wave device includes a piezoelectric substrate 100, a piezoelectric layer 200, and IDT electrodes 300. A set of opposing and staggered IDT electrodes 300 are formed on the main surface of the piezoelectric layer 200 to excite elastic waves with a wavelength of λ. These elastic waves include Rayleigh waves, transverse shear waves, or Lamb waves. The constituent material includes at least one of aluminum, copper, platinum, gold, silver, titanium, nickel, chromium, molybdenum, or tungsten, and may also be a stacked structure of the aforementioned metallic materials. The piezoelectric layer 200 is stacked on the piezoelectric substrate 100, and its constituent material is lithium niobate with a thickness of 0.1λ to 0.4λ. Figure 2 This is a frequency-admittance characteristic diagram of the elastic wave device of the first embodiment of this application as a function of piezoelectric layer thickness, as shown below. Figure 2 As shown, in the admittance-frequency coordinate system, from top to bottom, the frequency-admittance characteristic curves of the elastic wave device are displayed for piezoelectric layer thicknesses of 0.1λ, 0.2λ, 0.3λ, 0.4λ, 0.5λ, 0.6λ, 0.7λ, 0.8λ, 0.9λ, and 1λ, respectively. When the piezoelectric layer thickness is between 0.1λ and 0.4λ, the clutter within the red dashed box can achieve a good suppression effect. When the piezoelectric layer thickness is between 0.2λ and 0.4λ, the clutter suppression effect is... Furthermore, the cutting angle of the piezoelectric layer 200 differs from that of the piezoelectric substrate 100. The piezoelectric layer 200 is cut along the Y direction with an X-direction propagation angle of -20° to 20°, or 150° to 210°. Specifically, the three crystal axes of the lithium niobate single crystal material are set as the X-axis, Y-axis, and Z-axis. The material is cut at the surface with the Z-axis as the normal after rotating -20° to 20°, or 150° to 210° from the Y-axis with the X-axis as the central axis, and the elastic wave propagates in the X-axis direction. In contrast, the piezoelectric substrate 100 is cut along the X direction with an X-direction cutting angle of 0° to 180°. Figure 3 The graph shows the variation characteristics of the electromechanical coupling coefficient and the piezoelectric layer cutting angle of the elastic wave device of this application, as shown in the figure. Figure 3 As shown, when the cutting angle of the piezoelectric layer 200 is within the aforementioned angle range, the electromechanical coupling coefficient of the passband region of the elastic wave device is greater than or equal to 15%, thereby enabling the elastic wave device to receive and transmit signals in more frequency bands. The piezoelectric substrate 100 is made of lithium tantalate, lithium niobate, or quartz, and the thickness ratio of the piezoelectric layer 200 to the piezoelectric substrate 100 is less than 0.1, more preferably less than 0.05.

[0041] Figure 4A frequency-admittance characteristic diagram of the elastic wave device of the first embodiment and a comparative example, wherein the comparative example has the same IDT electrode structure as the elastic wave device of the first embodiment, specifically, the IDT electrode is made of platinum, the excited wavelength λ is 1 μm, the metallization ratio is 0.5, and the IDT electrode thickness is 0.03λ, and the piezoelectric layer has the same material, cut angle, and thickness as the piezoelectric layer 200 of the first embodiment, specifically, the piezoelectric layer is made of lithium niobate, the thickness is 0.3λ, and the cut angle is 160° along the Y direction, except that the comparative example does not have the piezoelectric substrate 100, as shown in FIG. 10. The red curve is the admittance characteristic curve of the elastic wave device of the first embodiment, and the blue curve is the admittance characteristic curve of the elastic wave device of the comparative example. The passband region of the elastic wave device of the first embodiment and the comparative example is 3200 MHz to 3700 MHz. The elastic wave device of the comparative example has obvious spurious waves at 3300 MHz. The spurious waves of the elastic wave device of the first embodiment in the passband region are obviously smaller than those of the comparative example. Figure 4

[0042] Therefore, by providing the piezoelectric layer 200 and the piezoelectric substrate 300 with different cut angles and controlling the cut angle of the piezoelectric layer 200 to be -20° to 20° or 150° to 210° along the Y direction and the X direction propagation angle, the elastic wave device of the first embodiment provides a large bandwidth and effectively suppresses the spurious waves in the passband region, thereby solving the problem of large spurious waves in the SAW filter with a large bandwidth in the prior art.

[0043] Figure 5 is a cross-sectional view of the elastic wave device of the second embodiment, as shown in FIG. 11. In some embodiments, the piezoelectric layer 200 includes a first piezoelectric layer 210 and a second piezoelectric layer 220, and the first piezoelectric layer 210 is stacked on the second piezoelectric layer 220. The cut angle of the first piezoelectric layer 210, the cut angle of the second piezoelectric layer 220, and the cut angle of the piezoelectric substrate 100 are all different. Figure 5

[0044] Specifically, the main mode elastic wave in the first piezoelectric layer 210 and the second piezoelectric layer 220 of the present embodiment is a transverse shear wave. It should be noted that in other embodiments, the main mode elastic wave in at least one of the first piezoelectric layer 210 and the second piezoelectric layer 220 is a transverse shear wave, and the main mode elastic wave in the other layer can be a Rayleigh wave or a Lamb wave. The total thickness of the first piezoelectric layer 210 and the second piezoelectric layer 220 is controlled to be 0.1λ to 0.4λ, and the cut angle of the first piezoelectric layer 210, the cut angle of the second piezoelectric layer 220, and the cut angle of the piezoelectric substrate 100 are all different, so as to effectively control the acoustic velocity of the elastic wave and further improve the quality factor Q value of the elastic wave device.

[0045] ​​Figure 6 is a cross-sectional view of an elastic wave device of a third embodiment of the present application, as Figure 6 indicated, in some embodiments, the piezoelectric substrate 100 includes a first piezoelectric substrate 110 and a second piezoelectric substrate 120, the first piezoelectric substrate 110 is laminated on the second piezoelectric substrate 120; the cut angle of the piezoelectric layer 200, the cut angle of the first piezoelectric substrate 110 and the cut angle of the second piezoelectric substrate 120 are all different.

[0046] Specifically, by setting the cut angle of the first piezoelectric substrate 110 different from the cut angle of the second piezoelectric substrate 120, so that there is a sound velocity difference between the elastic waves in the first piezoelectric substrate 110 and the second piezoelectric substrate 120, thereby inhibiting the main mode elastic wave energy from leaking downward along the piezoelectric substrate.

[0047] Figure 7 is a cross-sectional view of an elastic wave device of a fourth embodiment of the present application, as Figure 7 indicated, in some embodiments, the piezoelectric layer 200 and the piezoelectric substrate 100 further include an adhesive layer 400; the constituting material of the adhesive layer 400 includes at least one of silicon, titanium, nickel, chromium or tungsten.

[0048] Specifically, the adhesive layer 400 is arranged between the piezoelectric substrate 100 and the piezoelectric layer 200 to improve the bonding effect between the piezoelectric layer 200 and the piezoelectric substrate 100.

[0049] Figure 8 is a cross-sectional view of an elastic wave device of a fifth embodiment of the present application, as Figure 8 indicated, in some embodiments, the piezoelectric layer 200 and the piezoelectric substrate 100 further include a temperature compensation layer 500.

[0050] Specifically, the constituting material of the temperature compensation layer 500 is a positive temperature coefficient material with temperature compensation characteristics such as silicon oxide, so that the elastic wave device has good temperature characteristics, reduces the stress influence between the piezoelectric layer 200 and the piezoelectric substrate 100 due to temperature changes, and improves the reliability and service life of the elastic wave device.

[0051] Figure 9 is a cross-sectional view of an elastic wave device of a sixth embodiment of the present application, as Figure 9 indicated, in some embodiments, the piezoelectric layer 200 and the piezoelectric substrate 100 further include a high sound velocity layer 520 and a low sound velocity layer 510.

[0052] Specifically, the high-velocity layer 520 is made of silicon carbide or silicon nitride, and the low-velocity layer 510 is made of silicon oxide, gallium arsenide, or tantalum oxide. By setting the high-velocity layer 520 and the low-velocity layer 510, the cutoff frequency of the piezoelectric substrate 100 is adjusted, causing higher-order clutter to leak towards the piezoelectric substrate 100, thereby suppressing higher-order clutter.

[0053] The elastic wave device of this application will be described below through preferred embodiments.

[0054] Figure 10 This is a cross-sectional view of the elastic wave device according to a preferred embodiment of this application, as shown below. Figure 10 As shown, the elastic wave device of this preferred embodiment includes a piezoelectric substrate 100, a piezoelectric layer 200, and an IDT electrode 300. The IDT electrode 300 is formed on the main surface of the piezoelectric layer 200 and is used to excite elastic waves with a wavelength of λ. The piezoelectric layer 200 is located on the piezoelectric substrate 100. The piezoelectric layer 200 is made of lithium niobate and has a thickness of 0.3λ. The cutting angle of the piezoelectric layer 200 is different from the cutting angle of the piezoelectric substrate 100. The piezoelectric substrate 100 is made of lithium niobate cut along the Y direction with a propagation angle of 160° in the X direction. The thickness ratio of the piezoelectric layer 200 to the piezoelectric substrate 100 is 0.01. The piezoelectric substrate 100 includes a first piezoelectric substrate 110 and a second piezoelectric substrate 120, with the first piezoelectric substrate 110 stacked on top of the second piezoelectric substrate 120. The cutting angles of the piezoelectric layer 200, the first piezoelectric substrate 110, and the second piezoelectric substrate 120 are all different. Between the piezoelectric layer 200 and the piezoelectric substrate 100, from top to bottom, an adhesion layer 400, a low-velocity layer 510, an adhesion layer 400, a high-velocity layer 520, and another adhesion layer 400 are stacked sequentially. The adhesion layer 400 is made of silicon, the low-velocity layer 510 is made of silicon oxide. Since silicon oxide is a positive temperature coefficient material, the low-velocity layer 510 can also play a role in temperature compensation. The high-velocity layer 520 is made of silicon carbide.

[0055] The elastic wave device obtained through the above steps solves the problem of large noise in the existing SAW filter with large bandwidth, and effectively reduces the insertion loss at the high end of the filter passband.

[0056] Figure 11 This is a cross-sectional view of a module of an elastic wave device according to an embodiment of this application, as shown below. Figure 11As shown, the module of the elastic wave device includes the elastic wave device 600, the inductor 700, the sealing part 900, the wiring substrate 800, the IC integrated circuit component 801 and the connecting terminal 802. The connecting terminal 802 is formed on the lower surface of the wiring substrate 800 and is connected with the external circuit mainboard; the IC integrated circuit component 801 is installed inside the wiring substrate 800, and the IC integrated circuit component 801 includes a switch circuit and a low noise amplifier. The inductor 700 is installed on the main surface of the wiring substrate 800 and is used for realizing impedance matching of the signal transmission circuit. It should be noted that the inductor 700 can also be other passive devices in other embodiments. The sealing part 900 described above is used to seal the elastic wave device 600 and the inductor 700 and the like.

[0057] The expressions and terms used in the utility model are only for illustration and should not be regarded as limitation. The use of "including", "possessing", "having", "containing" and their variants in this document means including the following enumerated items, their equivalents and additional items.

[0058] The word "embodiment" in this application refers to the specific features, structures or characteristics described in conjunction with the embodiments, which can be included in at least one embodiment of this application. The appearance of this phrase in various places in the specification does not necessarily mean the same embodiment, nor does it mean independence or alternative to other embodiments. It is clear or implicitly understood by those skilled in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0059] The above-described embodiments only express several implementation manners of the application, which are described in detail and specifically, but should not be understood as limitation of the patent protection scope. It should be pointed out that for those skilled in the art, without departing from the concept of the application, some modifications, corrections and improvements can be made, which are all within the protection scope of the application. Therefore, the protection scope of the application should be subject to the appended claims.

Claims

1. An elastic wave device comprising a piezoelectric substrate, a piezoelectric layer and an IDT electrode, characterized in that, the IDT electrode is formed on a main surface of the piezoelectric layer for exciting an elastic wave having a wavelength of λ; the piezoelectric layer is laminated on the piezoelectric substrate; wherein the piezoelectric layer is made of lithium niobate; the piezoelectric layer has a cut angle different from that of the piezoelectric substrate; the cut angle of the piezoelectric layer is -20° to 20° or 150° to 210° in the Y direction; and the thickness ratio of the piezoelectric layer to the piezoelectric substrate is less than 0.

1.

2. The elastic wave device according to claim 1, characterized by, the piezoelectric layer comprises a first piezoelectric layer and a second piezoelectric layer, and the first piezoelectric layer is laminated on the second piezoelectric layer; the cut angle of the first piezoelectric layer, the cut angle of the second piezoelectric layer and the cut angle of the piezoelectric substrate are all different.

3. The elastic wave device according to claim 1, characterized by, the piezoelectric substrate comprises a first piezoelectric substrate and a second piezoelectric substrate, and the first piezoelectric substrate is laminated on the second piezoelectric substrate; the cut angle of the piezoelectric layer, the cut angle of the first piezoelectric substrate and the cut angle of the second piezoelectric substrate are all different.

4. The elastic wave device according to claim 1, characterized by, the piezoelectric substrate is made of lithium tantalate, lithium niobate or quartz.

5. The elastic wave device according to claim 1, characterized in that, the thickness of the piezoelectric layer is 0.1λ to 0.4λ.

6. The elastic wave device according to claim 1, characterized in that, an adhesive layer is further included between the piezoelectric layer and the piezoelectric substrate; and the adhesive layer is made of at least one of silicon, titanium, nickel, chromium or tungsten.

7. The elastic wave device according to claim 1, characterized in that, a temperature compensation layer is further included between the piezoelectric layer and the piezoelectric substrate.

8. The elastic wave device of claim 1, wherein, a high acoustic velocity layer and a low acoustic velocity layer are further included between the piezoelectric layer and the piezoelectric substrate.

9. The elastic wave device according to claim 8, characterized in that, the high acoustic velocity layer is made of silicon carbide or silicon nitride; and the low acoustic velocity layer is made of silicon oxide.

10. A module characterized in that, an elastic wave device as claimed in any one of claims 1 to 9.

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