Piezoelectric layer is a filter of aluminum nitride doped with scandium and electronic equipment

Abstract

The application relates to a filter comprising a plurality of bulk acoustic resonators, wherein: the bulk acoustic resonator comprises a piezoelectric layer, the piezoelectric layer is scandium-doped aluminum nitride, the doping concentration of scandium is in the range of 10% to 14%; the filter is a filter of a Band1 frequency band; and at a transmitting end of the filter, the thickness of the piezoelectric layer ranges between 0.503 mu m and 0.696 mu m, at a receiving end of the filter, the thickness of the piezoelectric layer ranges between 0.439 mu m and 0.647 mu m, or the filter is a filter of a Band3 frequency band; and at a transmitting end of the filter, the thickness of the piezoelectric layer ranges between 0.542 mu m and 0.759 mu m, at a receiving end of the filter, the thickness of the piezoelectric layer ranges between 0.519 mu m and 0.72 mu m. The application also relates to an electronic device comprising the filter.

Description

TECHNICAL FIELD

[0001] Embodiments of the present application relate to the field of semiconductor, and in particular, to a filter and an electronic device. BACKGROUND

[0002] With the development of 5G communication technology, the communication technology puts forward higher and higher requirements on the large bandwidth of the filter. Under this premise, the design of the filter puts forward urgent needs for the resonator with larger effective electromechanical coupling coefficient (kt 2 ).

[0003] As a new type of MEMS device, the film bulk acoustic resonator (FBAR) has the advantages of small size, light weight, low insertion loss, wide frequency band, and high quality factor, which well adapts to the upgrading of wireless communication systems.

[0004] There is a demand for reducing the size of the current filter device. There are two main ways to reduce the size of the device, one is to optimize the layout and improve the proportion of the effective area (resonator effective area) in the entire device layout, and the other is to reduce the size of the resonator. Optimizing the layout usually does not affect the performance of the resonator because it does not involve changing the resonator structure, but reducing the size of the resonator will affect the resonator itself. Whether it is a change in structure or a change in material, it will have a great impact on the performance of the resonator.

[0005] Therefore, how to reduce the area of the filter while ensuring that the performance of the resonator does not deteriorate significantly is a problem that needs to be solved in reality. SUMMARY

[0006] To alleviate or solve at least one aspect of the above problems in the prior art, the present application is proposed.

[0007] According to one aspect of an embodiment of the present application, it is proposed

[0008] A filter comprising a plurality of bulk acoustic resonators, wherein:

[0009] The bulk acoustic resonator comprises a piezoelectric layer, and the piezoelectric layer is scandium-doped aluminum nitride, and the doping concentration of scandium is in the range of 10% to 14%;

[0010] The filter is a filter of Band1 frequency band; and

[0011] The thickness of the piezoelectric layer is in the range of 0.503 μm to 0.696 μm at the transmitting end of the filter, and the thickness of the piezoelectric layer is in the range of 0.439 μm to 0.647 μm at the receiving end of the filter.

[0012] Embodiments of the present application also relate to a filter comprising a plurality of bulk acoustic resonators, wherein:

[0013] The bulk acoustic resonator comprises a piezoelectric layer, which is scandium-doped aluminum nitride, the doping concentration of scandium being in the range of 10%-14%;

[0014] The filter is a filter of Band 3 frequency band; and

[0015] The thickness of the piezoelectric layer is in the range of 0.542 μm to 0.759 μm at the transmitting end of the filter, and in the range of 0.519 μm to 0.72 μm at the receiving end of the filter.

[0016] Embodiments of the present application also relate to an electronic device comprising the filter described above. BRIEF DESCRIPTION OF DRAWINGS

[0017] The following description and drawings can better help understand these and other features and advantages of the various embodiments disclosed of the present application, wherein:

[0018] Figure 1 is a schematic cross-sectional view of a bulk acoustic resonator;

[0019] Figure 2 is a graph showing the variation trend of the 50-ohm resonator area (Kum 2 ) with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer;

[0020] Figure 3 is a graph showing the variation trend of the parallel impedance of a 50-ohm resonator with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer for a resonant frequency of 2 GHz;

[0021] Figure 4 is a graph showing the variation trend of the piezoelectric layer thickness of a resonator at the transmitting end of a filter of Band 3 frequency band with the scandium doping concentration according to an exemplary embodiment of the present application;

[0022] Figure 5 is a graph showing the variation trend of the piezoelectric layer thickness of a resonator at the receiving end of a filter of Band 3 frequency band with the scandium doping concentration according to an exemplary embodiment of the present application;

[0023] Figure 6 is a graph showing the variation trend of the piezoelectric layer thickness of a resonator at the transmitting end of a filter of Band 1 frequency band with the scandium doping concentration according to an exemplary embodiment of the present application;

[0024] Figure 7 is a graph showing the variation trend of the piezoelectric layer thickness of a resonator at the receiving end of a filter of Band 1 frequency band with the scandium doping concentration according to an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be further specifically described below through examples and in conjunction with the accompanying drawings. The following description of the embodiments of the present invention with reference to the accompanying drawings is intended to explain the overall inventive concept of the present invention and should not be understood as a limitation of the present invention. These are some embodiments of the invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field fall within the scope of protection of the present invention.

[0026] Figure 1 A cross-sectional view showing a typical sandwich-structured bulk acoustic wave resonator. Figure 1 In the figure, the reference numerals are described as follows:

[0027] 101: Substrate, optional materials include single crystal silicon, gallium nitride, gallium arsenide, sapphire, quartz, silicon carbide, diamond, etc.

[0028] 102: Acoustic mirror, which can be a cavity, a Bragg reflector layer or other equivalent forms. In the embodiment of the present invention, a cavity form is adopted.

[0029] 103: Bottom electrode (including bottom electrode pin), the material can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof.

[0030] 104: piezoelectric layer, which in the embodiment of the present invention is a scandium-doped aluminum nitride piezoelectric layer, which can be a single crystal piezoelectric layer or a polycrystalline piezoelectric layer.

[0031] 105: Top electrode (including top electrode pin), the material of which can be molybdenum, ruthenium, gold, aluminum, magnesium, tungsten, copper, titanium, iridium, osmium, chromium or a composite of the above metals or an alloy thereof.

[0032] 106: a passivation layer or a process layer, which may be aluminum nitride, silicon nitride, or silicon dioxide, etc. The passivation layer or the process layer 106 may not be provided.

[0033] The doping concentrations of elements doped in the piezoelectric layer will be briefly described below.

[0034] Doping means that a part of one or more elements in the originally undoped piezoelectric material is replaced by a doping element. At this time, the doping concentration is defined as the ratio of the number of atoms of the doping element to the sum of the number of atoms of the one or more elements replaced by the doping element and the number of atoms of the doping element in a unit volume. For example, in the case where the piezoelectric layer is aluminum nitride and the doping element is scandium (i.e., the piezoelectric layer is scandium-doped aluminum nitride ALScN), a part of aluminum atoms is replaced by scandium atoms, and the doping concentration is the ratio of the number of scandium atoms to the sum of the number of aluminum atoms and the number of scandium atoms in a unit volume (Sc / Al+Sc).

[0035] Figure 2 A graph showing the change trend of the 50-ohm resonator area of the transmitting end of the filter of the Band 1 frequency band with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer is shown by way of example. As shown in FIG. 1, as the doping concentration of the Sc element in the AlN, i.e., the scandium doping concentration in the AlScN, is increased, the electromechanical coupling coefficient kt Figure 2 of the resonator is ensured, and the 50-ohm resonator area is reduced. As the scandium doping concentration is increased, the 50-ohm resonator area is reduced. However, as the Sc concentration in the AlN is increased, it becomes more and more difficult to prepare a high-quality thin film, thereby causing the performance of the resonator to be reduced. 2

[0036] Figure 3 A graph showing the change trend of the parallel impedance of the 50-ohm resonator with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer is shown by way of example for the resonant frequency of 2 GHz. In FIG. 2, the ordinate is the parallel impedance of the 50-ohm resonator, and the abscissa is the scandium doping concentration. For the parallel impedance Rp, 1 is equivalent to the Rp at the concentration of 8%, and the other points are expressed in percentage of the Rp at the concentration of 8%. As shown in FIG. 2, as the scandium doping concentration is increased, the parallel impedance of the 50-ohm resonator is reduced. Figure 3 Figure 3 As shown in FIG. 2, when the doping concentration reaches 20%, the parallel impedance of the 50-ohm resonator is significantly reduced relative to the doping concentrations of 12% and 8%, whereas the parallel impedance of the 50-ohm resonator is equivalent at the doping concentrations of 12% and 8%. The main reason for this phenomenon is the difference in the quality of the thin film. As the doping concentration of Sc is increased, the Sc element begins to aggregate and crystallize due to the deposition temperature and the stress of the thin film, thereby forming separate Sc crystals inside the piezoelectric material. Such small Sc crystals destroy the crystallinity of the piezoelectric material itself and increase the material acoustic loss of the piezoelectric layer in the form of impurities. Ultimately, the performance of the resonator prepared using such a piezoelectric material with Sc crystals is significantly deteriorated.

[0037] Figures 4-7 A graph showing the change trend of the 50-ohm resonator area of the transmitting end of the filter of the Band 1 frequency band with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer is shown by way of example. As shown in FIG. 1, as the doping concentration of the Sc element in the AlN, i.e., the scandium doping concentration in the AlScN, is increased, the electromechanical coupling coefficient kt 2 ​​Under the premise of invariable, the thickness of the piezoelectric layer of the Band3 frequency band and the Band1 frequency band is reduced. In the case of fixed frequency band, the reduction of the piezoelectric layer leads to the reduction of the area of the 50 ohm resonator.

[0038] In the present application, the filter for the Band1 frequency band (Band1 frequency band is abbreviated as B1 in the drawing) means that the frequency range of the transmitting end of the filter is 1.92GHz-1.98GHz, and the frequency range of the receiving end of the filter is 2.11GHz-2.17GHz; the filter for the Band3 frequency band (Band3 frequency band is abbreviated as B3 in the drawing) means that the frequency range of the transmitting end of the filter is 1.71GHz-1.785GHz, and the frequency range of the receiving end of the filter is 1.805GHz-1.88GHz.

[0039] Figure 4 The figure showing the thickness of the scandium-doped aluminum nitride piezoelectric layer of the resonator of the transmitting end of the filter for the Band3 frequency band varying with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer according to an exemplary embodiment of the present application. In the figure, Figure 4 the vertical coordinate is the thickness of the piezoelectric layer of the resonator (unit: μm), and the horizontal coordinate is the doping concentration of scandium.

[0040] Figure 5 The figure showing the thickness of the scandium-doped aluminum nitride piezoelectric layer of the resonator of the receiving end of the filter for the Band3 frequency band varying with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer according to an exemplary embodiment of the present application. In the figure, Figure 5 the vertical coordinate is the thickness of the piezoelectric layer of the resonator (unit: μm), and the horizontal coordinate is the doping concentration of scandium.

[0041] Figure 6 The figure showing the thickness of the scandium-doped aluminum nitride piezoelectric layer of the resonator of the transmitting end of the filter for the Band1 frequency band varying with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer according to an exemplary embodiment of the present application. In the figure, Figure 6 the vertical coordinate is the thickness of the piezoelectric layer of the resonator (unit: μm), and the horizontal coordinate is the doping concentration of scandium.

[0042] Figure 7 The figure showing the thickness of the scandium-doped aluminum nitride piezoelectric layer of the resonator of the receiving end of the filter for the Band1 frequency band varying with the scandium doping concentration in the scandium-doped aluminum nitride piezoelectric layer according to an exemplary embodiment of the present application. In the figure, Figure 7 the vertical coordinate is the thickness of the piezoelectric layer of the resonator (unit: μm), and the horizontal coordinate is the doping concentration of scandium.

[0043] For the filter, the greater the thickness of the piezoelectric layer, the greater the kt 2Under the premise of invariability, the area of the piezoelectric layer will increase, which is not conducive to the miniaturization of the filter device; however, if the thickness of the piezoelectric layer is too small, kt 2 Under the premise of invariability, the area of the piezoelectric layer will decrease greatly, which is not conducive to the heat dissipation of the filter device, resulting in a decrease in the power capacity of the resonator, which will have a great impact on the performance of the resonator. In addition, as mentioned above, as the Sc concentration in AlN increases, it becomes more and more difficult to prepare a high-quality thin film, thereby resulting in a decrease in the performance of the resonator. Based on the above, for the resonator at the transmitting end and the resonator at the receiving end of the filter, when the piezoelectric layer is a scandium-doped piezoelectric layer, the doping concentration thereof is selected to be 10-14%, and the thickness of the piezoelectric layer is between 0.40 μm and 0.80 μm.

[0044] In an embodiment of the present application, for a Band3 frequency band filter, referring to Figures 4-5 , the thickness of the piezoelectric layer at the transmitting end (indicated as TX in the drawings) of the filter ranges from 0.542 μm to 0.759 μm, and the thickness of the piezoelectric layer at the receiving end (indicated as RX in the drawings) of the filter ranges from 0.519 μm to 0.72 μm.

[0045] In an embodiment of the present application, for a Band1 frequency band filter, referring to Figures 6-7 , the thickness of the piezoelectric layer at the transmitting end of the filter ranges from 0.503 μm to 0.696 μm, and the thickness of the piezoelectric layer at the receiving end of the filter ranges from 0.439 μm to 0.647 μm.

[0046] It should be noted that, in the present application, for each numerical range of the doping concentration and the thickness of the piezoelectric layer, in addition to the fact that the end point values are not included, the median values of each numerical range can also be included, which are all within the protection scope of the present application.

[0047] As can be understood by those skilled in the art, the bulk acoustic wave resonator can be used to form other semiconductor devices other than the filter.

[0048] Based on the above, the present application proposes the following technical solutions:

[0049] 1. A filter comprising a plurality of bulk acoustic wave resonators, wherein:

[0050] The bulk acoustic wave resonator comprises a piezoelectric layer, the piezoelectric layer being scandium-doped aluminum nitride, and the doping concentration of scandium being within a range of 10%-14%;

[0051] The filter is a Band1 frequency band filter; and

[0052] At the transmitting end of the filter, the thickness of the piezoelectric layer ranges between 0.503 and 0.696 μm, and at the receiving end of the filter, the thickness of the piezoelectric layer ranges between 0.439 and 0.647 μm.

[0053] 2. A filter comprising a plurality of bulk acoustic wave resonators, wherein:

[0054] The bulk acoustic wave resonator comprises a piezoelectric layer, the piezoelectric layer being scandium-doped aluminum nitride, the doping concentration of scandium ranging from 10% to 14%;

[0055] The filter is a filter of the Band 3 frequency band; and

[0056] At the transmitting end of the filter, the thickness of the piezoelectric layer ranges between 0.542 and 0.759 μm, and at the receiving end of the filter, the thickness of the piezoelectric layer ranges between 0.519 and 0.72 μm.

[0057] 3. An electronic device comprising the filter according to claim 1 or 2. Here, the electronic device includes, but is not limited to, intermediate products such as radio frequency front ends, filter amplification modules, and terminal products such as mobile phones, WIFI, and unmanned aerial vehicles.

[0058] Although embodiments of the present application have been shown and described, it is to be understood that various modifications can be made to these embodiments without departing from the principles and spirit of the application, the scope of which is to be determined by the appended claims and their equivalents.

Claims

1. A filter comprising a plurality of bulk acoustic wave resonators, wherein: The bulk acoustic wave resonator includes a piezoelectric layer, wherein the piezoelectric layer is scandium-doped aluminum nitride, and the scandium doping concentration is in the range of 10%-14%; The filter is a Band 1 filter, which means that the frequency range at the transmitting end of the filter is 1.92 GHz–1.98 GHz, and the frequency range at the receiving end of the filter is 2.11 GHz–2.17 GHz; and At the transmitting end of the filter, the thickness of the piezoelectric layer ranges from 0.503 μm to 0.696 μm, and at the receiving end of the filter, the thickness of the piezoelectric layer ranges from 0.439 μm to 0.647 μm.

2. A filter comprising a plurality of bulk acoustic wave resonators, wherein: The bulk acoustic wave resonator includes a piezoelectric layer, wherein the piezoelectric layer is scandium-doped aluminum nitride, and the scandium doping concentration is in the range of 10%-14%; The filter is a Band 3 filter, which means that the frequency range of the filter at the transmitting end is 1.71 GHz–1.785 GHz, and the frequency range of the filter at the receiving end is 1.805 GHz–1.88 GHz; and At the transmitting end of the filter, the thickness of the piezoelectric layer ranges from 0.542 μm to 0.759 μm, and at the receiving end of the filter, the thickness of the piezoelectric layer ranges from 0.519 μm to 0.72 μm.

3. An electronic device comprising the filter according to claim 1 or 2.

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