JP6666017B2 - Bulk acoustic resonator - Google Patents

Description

  The present invention relates to a bulk acoustic resonator.

  In recent years, interest in technology for 5G communication has been increasing, and technology that can be realized in candidate bands is being actively developed.

  On the other hand, a frequency band that can be realized by a film bulk acoustic resonator (FBAR) is approximately 6 GHz or less. In the case of the film-type bulk acoustic resonator driven in the frequency band of 2 to 3 GHz, the thickness of the electrode and the piezoelectric layer can be easily realized, but the film-type bulk acoustic resonator driven in the frequency band of 5 GHz In the case of, an increase in process difficulty and a deterioration in performance are expected.

  In particular, in the case of a film-type bulk acoustic resonator driven in a frequency band of 5 GHz, it is necessary to realize an ultra-thin film electrode, and the thickness of the piezoelectric layer is necessarily reduced. By the way, when an electrode material having a high acoustic impedance such as molybdenum (Mo) is used, an electrical loss due to a decrease in thickness is expected to increase, and further, a resonator and a filter device are required. Is also expected to increase in electrical loss.

  However, when an electrode material having a low acoustic impedance such as aluminum (Al) is used, the mechanical property of aluminum (Al) is poor, so that the mechanical dynamic loss is low. ) Is expected to increase, and there is a problem that the crystal orientation deteriorates when the piezoelectric layer is formed.

  That is, when an electrode material having a high acoustic impedance such as molybdenum (Mo) is used, the thickness of the upper electrode and the lower electrode is set to 1000 ° and the thickness of the piezoelectric layer is set to 3000 ° unless the thickness of the piezoelectric layer is set to 5 °. Frequency cannot be realized. However, when an electrode material having a low acoustic impedance such as aluminum (Al) is used, a frequency of 5 GHz is realized even if the thickness of the upper electrode and the lower electrode is 2000 mm and the thickness of the piezoelectric layer is 4000 mm. be able to.

  However, when the upper electrode and the lower electrode are formed only of aluminum (Al), mechanical properties are deteriorated, and hillocks are generated due to electron migration or mechanical deformation. The crystal orientation of the piezoelectric layer and the resonator performance may be deteriorated.

JP-A-1993-267776

  An object of the present invention is to provide a bulk acoustic resonator that can reduce performance degradation under high frequency (for example, 6 GHz) driving conditions and is easy to manufacture.

  A bulk acoustic resonator according to one embodiment of the present invention includes a substrate, a lower electrode disposed on the substrate, a piezoelectric layer at least partially disposed on the lower electrode, and a piezoelectric layer disposed on the lower electrode. And at least one of the lower electrode and the upper electrode may include an aluminum alloy layer containing scandium (Sc).

  According to the present invention, under driving conditions of a high frequency (for example, 6 GHz), performance degradation can be reduced, and there is an effect that manufacturing is easy.

  Furthermore, when the resonator is driven in the 4 to 6 GHz region, the electric loss can be reduced, and the crystal orientation of the piezoelectric layer can be improved.

FIG. 2 is a plan view illustrating a bulk acoustic resonator according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along the line II ′ of FIG. 1. FIG. 2 is a sectional view taken along the line II-II ′ of FIG. 1. FIG. 3 is a sectional view taken along the line III-III ′ of FIG. 1. 4 is a graph showing a sheet resistance change rate of an aluminum alloy containing pure aluminum and scandium. 4 is a photograph for explaining a surface defect of pure aluminum. It is a photograph for demonstrating the surface defect of a scandium containing aluminum alloy (0.625 at%). It is a photograph for demonstrating the surface defect of a scandium containing aluminum alloy (6.25 at%). 4 is a photograph showing the surface roughness of pure aluminum by a nuclear microscope. It is a photograph which shows the surface roughness of a scandium containing aluminum alloy (0.625 at%) with a nuclear microscope. It is a photograph which shows the surface roughness of a scandium containing aluminum alloy (6.25 at%) by an atomic force microscope. 5 is a photograph for explaining a surface defect of a piezoelectric layer formed on pure aluminum. 5 is a photograph for explaining a surface defect of a piezoelectric layer formed on a scandium-containing aluminum alloy (6.25 at%). 4 is a photograph for explaining a surface defect of a piezoelectric layer formed on a scandium-containing aluminum alloy (0.625 at%). FIG. 4 is a schematic sectional view illustrating a bulk acoustic resonator according to a second embodiment of the present invention. FIG. 9 is a schematic sectional view illustrating a bulk acoustic resonator according to a third embodiment of the present invention. FIG. 11 is a schematic sectional view illustrating a bulk acoustic resonator according to a fourth embodiment of the present invention. FIG. 11 is a schematic sectional view illustrating a bulk acoustic resonator according to a fifth embodiment of the present invention. FIG. 14 is a schematic sectional view illustrating a bulk acoustic resonator according to a sixth embodiment of the present invention. FIG. 14 is a schematic sectional view illustrating a bulk acoustic resonator according to a seventh embodiment of the present invention. FIG. 16 is a schematic sectional view illustrating a bulk acoustic resonator according to an eighth embodiment of the present invention. FIG. 15 is a schematic sectional view illustrating a bulk acoustic resonator according to a ninth embodiment of the present invention. FIG. 16 is a schematic sectional view illustrating a bulk acoustic resonator according to a tenth embodiment of the present invention. It is a schematic sectional drawing showing the bulk acoustic resonator by an 11th example of the present invention. FIG. 21 is a schematic sectional view illustrating a bulk acoustic resonator according to a twelfth embodiment of the present invention. FIG. 21 is a schematic sectional view illustrating a bulk acoustic resonator according to a thirteenth embodiment of the present invention. FIG. 21 is a schematic sectional view illustrating a bulk acoustic resonator according to a fourteenth embodiment of the present invention. FIG. 27 is a schematic sectional view showing a bulk acoustic resonator according to a fifteenth embodiment of the present invention. FIG. 24 is a schematic sectional view showing a bulk acoustic resonator according to a sixteenth embodiment of the present invention. It is a schematic sectional drawing showing the bulk acoustic resonator by a 17th example of the present invention. FIG. 35 is a schematic sectional view showing a bulk acoustic resonator according to an eighteenth embodiment of the present invention. It is a schematic sectional drawing showing the bulk acoustic resonator by a 19th example of the present invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those having average knowledge in the art. Therefore, the shapes and sizes of the elements in the drawings may be enlarged or reduced (or highlighted or simplified) for clearer explanation, and the elements denoted by the same reference numerals in the drawings are the same. Is the element.

  FIG. 1 is a plan view illustrating a bulk acoustic resonator according to a first embodiment of the present invention, FIG. 2 is a cross-sectional view taken along line II ′ of FIG. 1, and FIG. FIG. 4 is a cross-sectional view taken along the line '′, and FIG. 4 is a cross-sectional view taken along the line III-III ′ of FIG.

  1 to 4, a bulk acoustic resonator 100 according to a first embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 150, a piezoelectric layer. 160, an upper electrode 170, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  Substrate 110 can be a silicon substrate. For example, a silicon wafer may be used as the substrate 110, and an SOI (Silicon On Insulator) type substrate may be used.

  An insulating layer 112 may be formed on an upper surface of the substrate 110, so that components disposed above and the substrate 110 can be electrically isolated. In addition, the insulating layer 112 serves to prevent the etching gas from etching the substrate 110 when forming the cavity C during the manufacturing process.

In this case, the insulating layer 112 may be made of at least one of silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₂ ), and aluminum nitride (AlN), It may be formed by any one of chemical vapor deposition, RF magnetron sputtering, and evaporation.

  The sacrificial layer 120 is formed on the insulating layer 112, and the cavity C and the anti-etching unit 130 may be disposed inside the sacrificial layer 120. The cavity C is formed by removing a part of the sacrificial layer 120 during manufacturing. Since the cavity C is formed inside the sacrifice layer 120, the lower electrode 150 and the like disposed on the sacrifice layer 120 are formed flat.

  The anti-etching part 130 is disposed along the boundary of the cavity C. The anti-etching unit 130 prevents the cavity C from being etched beyond the cavity area in the process of forming the cavity C.

The membrane layer 140 forms the cavity C together with the substrate 110. Further, the membrane layer 140 may be made of a material having low reactivity with an etching gas when the sacrificial layer 120 is removed. In addition, the etching prevention unit 130 is inserted and arranged in the groove 142 formed by the membrane layer 140. On the other hand, as the membrane layer 140, silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), and lead zirconate titanate (PZT) ), Gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and a dielectric layer containing any one of zinc oxide (ZnO) (Dielectric layer) may be used.

  Note that a seed layer (not shown) made of aluminum nitride (AlN) may be formed on the membrane layer 140. That is, the seed layer may be disposed between the membrane layer 140 and the lower electrode 150. The seed layer can be formed using a dielectric or a metal having an HCP crystal structure other than aluminum nitride (AlN). For example, when the seed layer is a metal, the seed layer may be formed of titanium (Ti).

  The lower electrode 150 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 150 can be used as one of an input electrode and an output electrode for inputting and outputting an electrical signal such as an RF (Radio Frequency) signal.

  Meanwhile, the lower electrode 150 may be made of, for example, an aluminum alloy material containing scandium (Sc). Accordingly, mechanical strength is increased, and high-power reactive sputtering can be performed. With such deposition conditions, an increase in surface roughness of the lower electrode 150 can be suppressed, and highly oriented growth of the piezoelectric layer 160 can be induced.

  In addition, since scandium (Sc) is included, the chemical resistance of the lower electrode 150 increases, and a problem that occurs in the lower electrode made of pure aluminum can be compensated. Process stability such as dry etching or wet process can be ensured. Furthermore, although oxidation is likely to occur in the lower electrode made of pure aluminum, the lower electrode 150 is made of an aluminum alloy material containing scandium, whereby the chemical resistance to oxidation is improved.

  This will be described in more detail. First, an electrode was formed from a molybdenum (Mo) material and an aluminum alloy (AlSc) material containing scandium so as to have a thickness of 1500 °, and the sheet resistance was measured. Although the sheet resistance was 0.9685, the sheet resistance of the electrode made of an aluminum alloy (AlSc) material containing 0.625 at% of scandium was 0.316. Thus, it can be seen that the sheet resistance of the electrode made of the aluminum alloy (AlSc) material is lower than that of the electrode made of the molybdenum (Mo) material.

  Meanwhile, the content of scandium (Sc) may be 0.1 at% to 5 at%. That is, if the content of scandium (Sc) is less than 0.1 at%, there is a possibility that mechanical properties may be reduced due to aluminum (Al) or hillocks may be generated, and the content of scandium (Sc) is 5 at% or more. In addition, it becomes difficult to improve an electrical loss indicating a sheet resistance. When the content of scandium (Sc) increases, the surface roughness increases, which may adversely affect the crystal orientation.

  And as can be seen from the above table, the yield strength increased and the elongation decreased in the scandium-containing aluminum alloy (AlSc, 0.625 at%) material compared to the pure aluminum (Al) material.

  Further, as shown in FIG. 5, a pure aluminum (Al) material and a scandium-containing aluminum alloy (AlSc, 0.625 at%) material are deposited so as to have a thickness of 1500 ° and have a high reliability. The sheet resistance change was measured under the environment. A comparison of the sheet resistance change rate after 96 hours shows that the scandium-containing aluminum alloy (AlSc, 0.625 at%) material shows a change in sheet resistance change rate of about 50% as compared with the pure aluminum (Al) material. It can be seen that they have excellent oxidation resistance characteristics.

  In addition, since the lower electrode 150 and the metal pad 195 have excellent galvanic corrosion characteristics, stability in a manufacturing process can be obtained. In this connection, an aluminum alloy (AlSc, 0.625 at%) material containing pure aluminum (Al) and scandium is deposited to have a thickness of 1500 ° and is mainly used as a material of the metal pad 195. After being brought into contact with gold (Au), it was immersed in an electrolyte solution for 65 hours to compare galvanic corrosion characteristics. As a result, no change in the surface was observed in the scandium-containing aluminum alloy (AlSc, 0.625 at%) material, but corrosion (corrosion) with gold (Au) was observed in the pure aluminum material. Therefore, by forming the lower electrode 150 from an aluminum alloy containing scandium (AlSc), characteristics against galvanic corrosion in the manufacturing process can be secured.

  On the other hand, the lower electrode 150 is made of an aluminum alloy (AlSc) containing only scandium (Sc). That is, no metal other than scandium (Sc) is contained. If a metal other than scandium (Sc) is further included, such an aluminum alloy forms a ternary system in a phase diagram. In this case, it is difficult to control the composition, and the phase system becomes complicated, so that a non-uniform composition or an unnecessary crystal phase may be formed.

  Further, when the lower electrode 150 is an aluminum alloy composed of a three-component system, the surface roughness increases due to the non-uniform composition and the formation of an unnecessary crystal phase, which adversely affects the crystal orientation during the formation of the piezoelectric layer 160. There is fear.

  Therefore, when the lower electrode 150 is made of an aluminum alloy (AlSc) containing only scandium (Sc), the crystal orientation of the piezoelectric layer 160 disposed above the lower electrode 150 is improved. This will be described later.

  The piezoelectric layer 160 is formed so as to cover at least the lower electrode 150 disposed above the cavity C. On the other hand, the piezoelectric layer 160 is a portion that causes a piezoelectric effect of converting electrical energy into mechanical energy of an elastic waveform, and is made of any of aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT). Can be formed by In particular, when the piezoelectric layer 160 is made of aluminum nitride (AlN), the piezoelectric layer 160 may further include a rare earth metal. For example, the rare earth metal can include at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, the transition metal may include at least one of titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), and niobium (Nb). Further, magnesium (Mg) which is a divalent metal may be contained.

  In addition, the content of elements contained in aluminum nitride (AlN) is preferably 0.1 to 30 at% in order to improve piezoelectric characteristics. If the content of the element contained for improving the piezoelectric characteristics is less than 0.1 at%, high piezoelectric characteristics cannot be realized as compared with aluminum nitride (AlN), and the piezoelectric characteristics are improved. If the content of the element contained in exceeds 30 at%, preparation for vapor deposition and adjustment of the composition become difficult, and a heterogeneous phase may be formed.

  On the other hand, the piezoelectric layer 160 includes a piezoelectric portion 162 disposed on the flat portion S and a bent portion 164 disposed on the extension portion E.

  The piezoelectric portion 162 is a portion directly laminated on the upper surface of the lower electrode 150. Therefore, the piezoelectric part 162 is interposed between the lower electrode 150 and the upper electrode 170, and is formed in a flat shape together with the lower electrode 150 and the upper electrode 170.

  The bent portion 164 extends outward from the piezoelectric portion 162 and can be defined as a region located in the expanded portion E.

  The bent portion 164 is arranged on an insertion layer 180 described later, and is formed in a form that is lifted along the shape of the insertion layer 180. Therefore, the piezoelectric layer 160 is bent at the boundary between the piezoelectric portion 162 and the bent portion 164, and the bent portion 164 is lifted according to the thickness and shape of the insertion layer 180.

  The bent part 164 may be divided into a slope part 164a and an extension part 164b.

  The inclined portion 164a refers to a portion formed to be inclined along an inclined surface L of the insertion layer 180 described later. Further, the extension portion 164b refers to a portion that extends outward from the inclined portion 164a.

  The inclined portion 164a is formed parallel to the inclined surface L of the insertion layer 180, and the inclined angle of the inclined portion 164a is formed to have the same angle as the inclined angle (θ in FIG. 3) of the inclined surface L of the insertion layer 180. Can be done.

  The upper electrode 170 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 170 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 150 is used as an input electrode, the upper electrode 170 can be used as an output electrode, and when the lower electrode 150 is used as an output electrode, the upper electrode 170 can be used as an input electrode.

  Meanwhile, the upper electrode 170 may be made of an aluminum alloy material containing scandium (Sc), like the lower electrode 150.

The insertion layer 180 is disposed between the lower electrode 150 and the piezoelectric layer 160. The insertion layer 180 is made of silicon oxide (SiO ₂ ), aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), manganese oxide (MgO), zirconium oxide (ZrO ₂ ), and titanium. It is made of a dielectric material such as lead zirconate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO). But made of a material different from that of the piezoelectric layer 160. Further, if necessary, the region where the insertion layer 180 is provided can be formed as an empty space (air). However, this can be realized by removing the insertion layer 180 during the manufacturing process.

  In this embodiment, the thickness of the insertion layer 180 may be the same as or similar to the thickness of the lower electrode 150. In addition, the thickness of the piezoelectric layer 160 may be similar to or smaller than the thickness of the piezoelectric layer 160. For example, the insertion layer 180 may be formed to have a thickness of 100 ° or more, and may be formed to be thinner than the thickness of the piezoelectric layer 160. However, the configuration of the present invention is not limited to this.

  Meanwhile, the insertion layer 180 is disposed along a surface formed by the membrane layer 140, the lower electrode 150, and the etching prevention unit 130.

  The insertion layer 180 is disposed around the flat portion S and supports the bent portion 164 of the piezoelectric layer 160. Therefore, the bent portion 164 of the piezoelectric layer 160 can be divided into an inclined portion 164a and an extended portion 164b according to the shape of the insertion layer 180.

  The insertion layer 180 is arranged in a region excluding the flat portion S. For example, the insertion layer 180 may be disposed in the entire region except the flat portion S, or may be disposed in a part of the region.

  At least a part of the insertion layer 180 is disposed between the piezoelectric layer 160 and the lower electrode 150.

  The side surface of the insertion layer 180 arranged along the boundary of the flat portion S is formed in such a manner that the thickness increases as the distance from the flat portion S increases. As a result, the side surface of the insertion layer 180 arranged so as to be adjacent to the flat portion S is formed as an inclined surface L having a constant inclination angle θ.

  In order to manufacture such that the inclination angle θ of the side surface of the insertion layer 180 is less than 5 °, the thickness of the insertion layer 180 must be extremely thin, or the area of the inclined surface L must be excessively large. The realization is virtually impossible.

  On the other hand, when the inclination angle θ of the side surface of the insertion layer 180 is greater than 70 °, the inclination angle of the inclined portion 164a of the piezoelectric layer 160 stacked on the insertion layer 180 is also greater than 70 °. At this time, since the piezoelectric layer 160 is excessively bent, a crack may be generated at a bent portion of the piezoelectric layer 160.

  Therefore, the inclination angle θ of the inclined surface L in the present embodiment is formed in the range of 5 ° to 70 °.

  The passivation layer 190 is formed in a region excluding a part of the lower electrode 150 and a part of the upper electrode 170. Meanwhile, the passivation layer 190 serves to prevent the upper electrode 170 and the lower electrode 150 from being damaged during the process.

Further, the passivation layer 190 can adjust the frequency by removing a part by etching in the final step. That is, the thickness of the passivation layer 190 can be adjusted. Examples of the passivation layer 190 include silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), and lead zirconate titanate (PZT). ), Gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and a dielectric layer containing any one of zinc oxide (ZnO) Can be used.

  The metal pad 195 is formed on a portion of the lower electrode 150 and the upper electrode 170 where the passivation layer 190 is not formed. As an example, the metal pad 195 is made of a material such as gold (Au), gold-tin (Au-Sn) alloy, copper (Cu), copper-tin (Cu-Sn) alloy, aluminum (Al), and aluminum alloy. Can be. For example, the aluminum alloy may be an aluminum-germanium (Al-Ge) alloy.

  As described above, since the lower electrode 150 and the upper electrode 170 are made of an aluminum alloy material containing scandium (Sc), electric loss can be improved.

  Further, since the mechanical strength can be improved, the more stable deposition of the piezoelectric layer 160 can be performed during the sputtering process, the crystal orientation can be improved, and the production stability can be ensured by improving the chemical resistance. .

  This will be described in more detail. First, an aluminum alloy (AlSc) containing pure aluminum (Al) and scandium (Sc) is deposited on a seed layer of aluminum nitride (AlN) material having a thickness of 500 ° to have a thickness of 1500 °. Observation of surface defects revealed that in pure aluminum (Al), many defects due to hillocks and grain boundary grooves were observed, but in an aluminum alloy (AlSc) containing scandium (Sc), hillocks were observed. Further, defects due to the crystal grain boundary grooves were significantly reduced.

  That is, as shown in FIGS. 6 to 8, in pure aluminum (Al), surface defects due to grooves are observed, and an aluminum alloy containing scandium (Sc) (AlSc, 0.625 at%) No surface defects were observed. Also, it can be seen that if the scandium (Sc) content is excessively high, the surface roughness will increase rather.

  More specifically, pure aluminum (Al), an aluminum alloy (AlSc) containing 0.625 at% of scandium (Sc), and an aluminum alloy (AlSc) containing 6.25 at% of scandium (Sc) are deposited. The surface roughness of the sample thus obtained was measured using an atomic force microscope (AFM). As a result, as shown in FIGS. 9 to 11, pure aluminum (Al) has a surface roughness (Ra) of 3.74 nm based on a scan size (10 μm × 10 μm) and a scandium (Sc) of 0. The aluminum alloy (AlSc) containing .625 at% had a surface roughness (Ra) of 1.70 nm based on a scan size (10 μm × 10 μm). In the case of an aluminum alloy (AlSc) containing 6.25 at% of scandium (Sc), the surface roughness (Ra) increased to 10.27 nm based on the scan size (10 μm × 10 μm).

  On the other hand, an aluminum alloy (AlSc) containing pure aluminum (Al) and scandium (Sc) has an FCC crystal structure. When oriented to the (111) crystal plane of the aluminum alloy (AlSc) FCC crystal structure, a lattice mismatch with the aluminum nitride (AlN) HCP crystal structure (0002) crystal plane of the piezoelectric layer 160 is obtained. Is 8%. That is, the lower electrode 150 is formed of an aluminum alloy (AlSc) material containing pure aluminum (Al) and scandium (Sc), compared with a lattice mismatch ratio of 14% when the lower electrode 150 is formed of a molybdenum (Mo) material. In this case, the lattice mismatch rate can be improved.

  However, in pure aluminum (Al), when the surface roughness increases due to surface defects or the like, the crystal orientation of the piezoelectric layer 160 deteriorates.

  An aluminum alloy (AlSc) containing pure aluminum (Al) and scandium (Sc) and molybdenum (Mo) have a thickness of 1500 mm on a seed layer of aluminum nitride (AlN) material having a thickness of 500 mm. Then, aluminum nitride (AlN) as the piezoelectric layer 160 is deposited to have a thickness of 5000 °, and an XRD rocking curve is measured to compare the crystal orientation of the thin film. As a result, the results are as shown in the following table.

  In the above table, when aluminum nitride (AlN) is deposited on molybdenum (Mo), the crystal orientation of aluminum nitride (AlN) becomes 1.95 °, and when aluminum nitride (AlN) is deposited on pure aluminum (Al), The crystal orientation was 1.73 ° due to surface defects of pure aluminum (Al). In other words, the crystal orientation of the piezoelectric layer is improved when pure aluminum (Al) is applied as compared with the case where molybdenum (Mo) is applied, but the depression observed on the surface of pure aluminum (Al) is improved. As shown in FIG. 12, the surface defects of the grooves are transferred as they are when aluminum nitride (AlN) is deposited. Further, in an aluminum alloy (AlSc) containing 6.25 at% of scandium (Sc), as shown in FIG. 13, the crystal orientation during aluminum nitride (AlN) deposition is 2. 19 ° (see Table 2), which is worse than pure aluminum (Al). However, in an aluminum alloy (AlSc) containing 0.625 at% of scandium (Sc), as shown in FIG. 14, the crystal orientation during the deposition of aluminum nitride (AlN) is 0.78 ° (see Table 2). And very excellent crystal orientation was obtained.

  In other words, more stable deposition of the piezoelectric layer 160 can be performed during the sputtering process, crystal orientation can be improved, and production stability can be ensured by improving chemical resistance.

  Hereinafter, modified embodiments of the bulk acoustic resonator according to the present invention will be described with reference to the accompanying drawings. However, the same constituent elements as those described above are shown in the drawings using the same reference numerals as used above, and detailed description thereof will be omitted.

  FIG. 15 is a schematic sectional view showing a bulk acoustic resonator according to a second embodiment of the present invention.

  Referring to FIG. 15, a bulk acoustic resonator 200 according to a second embodiment of the present invention includes, for example, a substrate 110, a sacrifice layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 250, a piezoelectric layer 160, and an upper layer. It may include an electrode 170, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 250 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 250 can be used as any of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  Meanwhile, the lower electrode 250 may be formed using a conductive material such as molybdenum (Mo) or an alloy thereof, for example. However, the present invention is not limited to this. It can be made of a conductive material such as Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  On the other hand, since the upper electrode 170 is made of an aluminum alloy material containing scandium (Sc) like the upper electrode 170 provided in the bulk acoustic resonator 100 according to the first embodiment of the present invention, chemical resistance is improved. Increase. That is, it is possible to compensate for the problem that occurs in the upper electrode made of a pure aluminum material, and to secure the process stability such as a dry etching process or a wet process even during manufacturing. Furthermore, oxidation is likely to occur in the upper electrode made of pure aluminum. However, since the upper electrode 170 is made of an aluminum alloy material containing scandium, chemical resistance to oxidation is improved.

  FIG. 16 is a schematic sectional view showing a bulk acoustic resonator according to a third embodiment of the present invention.

  Referring to FIG. 16, a bulk acoustic resonator 300 according to a third embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 150, a piezoelectric layer 160, an upper part. It may include an electrode 370, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The upper electrode 370 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 370 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 150 is used as an input electrode, the upper electrode 370 can be used as an output electrode, and when the lower electrode 150 is used as an output electrode, the upper electrode 370 can be used as an input electrode.

  The upper electrode 370 may be formed using a conductive material such as Molybdenum (Mo) or an alloy thereof, for example. However, the present invention is not limited to this. It can be made of a conductive material such as Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  Meanwhile, the lower electrode 150 is made of an aluminum alloy material containing scandium (Sc), like the lower electrode 150 provided in the bulk acoustic resonator 100 according to the first embodiment of the present invention. As a result, the mechanical strength is increased, and high power reactive sputtering can be performed. Under such deposition conditions, an increase in surface roughness of the lower electrode 150 can be suppressed, and highly oriented growth of the piezoelectric layer 160 can be induced.

  In addition, since scandium (Sc) is included, the chemical resistance of the lower electrode 150 is increased, and a problem that may occur with the lower electrode made of pure aluminum can be compensated. Process stability can be ensured. Furthermore, although oxidation is likely to occur in the lower electrode made of pure aluminum, the lower electrode 150 is made of an aluminum alloy material containing scandium, whereby the chemical resistance to oxidation is improved.

  FIG. 17 is a schematic sectional view showing a bulk acoustic resonator according to a fourth embodiment of the present invention.

  Referring to FIG. 17, a bulk acoustic resonator 400 according to a fourth embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 450, a piezoelectric layer 160, and an upper part. It may include an electrode 170, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 450 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 450 can be used as any of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  As an example, the lower electrode 450 includes a first lower electrode layer 452 made of an aluminum alloy material containing scandium (Sc), and a second lower electrode layer 454 formed on the first lower electrode layer 452.

  Meanwhile, the second lower electrode layer 454 may be formed using a conductive material such as Molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto. , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  As described above, since the upper electrode 170 and the first lower electrode layer 452 are made of an aluminum alloy material containing scandium (Sc), the chemical resistance increases, and a problem occurs in the lower electrode and the upper electrode made of pure aluminum. Therefore, even during manufacturing, it is possible to secure process stability such as a dry etching process or a wet process. Further, oxidation is likely to occur in the lower electrode and the upper electrode made of pure aluminum, but since the upper electrode 170 and the lower electrode 450 are made of an aluminum alloy material containing scandium, the chemical resistance to oxidation is improved. .

  FIG. 18 is a schematic sectional view showing a bulk acoustic resonator according to a fifth embodiment of the present invention.

  Referring to FIG. 18, a bulk acoustic resonator 500 according to a fifth embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 550, a piezoelectric layer 160, and an upper layer. It may include an electrode 570, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 550 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 550 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  As an example, the lower electrode 550 includes a first lower electrode layer 552 and a second lower electrode layer 554 formed on the first lower electrode layer 552 and made of an aluminum alloy material containing scandium (Sc). .

  Meanwhile, the first lower electrode layer 552 may be formed using a conductive material such as Molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto. , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  The upper electrode 570 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 570 can be used as any of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 550 is used as an input electrode, the upper electrode 570 can be used as an output electrode, and when the lower electrode 550 is used as an output electrode, the upper electrode 570 can be used as an input electrode.

  On the other hand, the upper electrode 570 includes a first upper electrode layer 572 made of an aluminum alloy material containing scandium (Sc), and a second upper electrode layer 574 formed on the first upper electrode layer 572.

  In addition, the second upper electrode layer 574 may be formed using a conductive material such as molybdenum (Molybdenum: Mo) or an alloy thereof. However, the present invention is not limited thereto. , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  As described above, the second lower electrode layer 554 is made of an aluminum alloy material containing scandium (Sc). As a result, the mechanical strength is increased, and high power reactive sputtering can be performed. Then, under such deposition conditions, an increase in surface roughness of the second lower electrode layer 554 can be suppressed, and highly oriented growth of the piezoelectric layer 160 can be induced.

  In addition, since the second lower electrode layer 554 and the first upper electrode layer 572 are made of an aluminum alloy material containing scandium (Sc), the chemical resistance increases, and a problem occurs in the lower electrode and the upper electrode made of pure aluminum. Therefore, even during manufacturing, it is possible to secure process stability such as a dry etching process or a wet process. Further, oxidation is likely to occur in the lower electrode and the upper electrode made of pure aluminum. However, since the second lower electrode layer 554 and the first upper electrode layer 572 are made of a scandium-containing aluminum alloy material, chemical resistance to oxidation is increased. Will be improved.

  FIG. 19 is a schematic sectional view showing a bulk acoustic resonator according to a sixth embodiment of the present invention.

  Referring to FIG. 19, for example, a bulk acoustic resonator 600 according to a sixth embodiment of the present invention includes a substrate 110, a sacrificial layer 120, an etch prevention unit 130, a membrane layer 140, a lower electrode 650, a piezoelectric layer 160, It may include an electrode 670, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 650 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 650 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  Meanwhile, the lower electrode 650 may be formed using a conductive material such as Molybdenum (Mo) or an alloy thereof, for example. However, the present invention is not limited to this. It can be made of a conductive material such as Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  The upper electrode 670 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 670 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 650 is used as an input electrode, the upper electrode 670 can be used as an output electrode, and when the lower electrode 650 is used as an output electrode, the upper electrode 670 can be used as an input electrode.

  On the other hand, the upper electrode 670 includes a first upper electrode layer 672 made of an aluminum alloy material containing scandium (Sc), and a second upper electrode layer 674 formed on the first upper electrode layer 672.

  In addition, the second upper electrode layer 674 may be formed using a conductive material such as molybdenum (Molybdenum: Mo) or an alloy thereof. However, the present invention is not limited thereto, and the second upper electrode layer 674 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  Since the first upper electrode layer 672 is made of an aluminum alloy material containing scandium (Sc), the chemical resistance increases, and the problem that occurs in the lower electrode and the upper electrode made of pure aluminum can be compensated. In addition, it is possible to secure process stability such as a dry etching process or a wet process. Furthermore, oxidation is likely to occur in the lower electrode and the upper electrode made of pure aluminum. However, when the first upper electrode layer 672 is made of an aluminum alloy material containing scandium, the chemical resistance to oxidation is improved.

  FIG. 20 is a schematic sectional view showing a bulk acoustic resonator according to a seventh embodiment of the present invention.

  Referring to FIG. 20, a bulk acoustic resonator 700 according to a seventh embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etch prevention unit 130, a membrane layer 140, a lower electrode 150, a piezoelectric layer 160, and an upper part. It may include an electrode 770, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The upper electrode 770 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 770 can be used as one of an input electrode and an output electrode for inputting and outputting an electrical signal such as an RF signal. That is, when the lower electrode 150 is used as an input electrode, the upper electrode 770 can be used as an output electrode, and when the lower electrode 150 is used as an output electrode, the upper electrode 770 can be used as an input electrode.

  On the other hand, the upper electrode 770 includes a first upper electrode layer 772 and a second upper electrode layer 774 disposed on the first upper electrode layer 772 and made of an aluminum alloy material containing scandium (Sc).

  In addition, the first upper electrode layer 772 may be formed using a conductive material such as molybdenum (Molybdenum: Mo) or an alloy thereof. However, the invention is not limited thereto, and the first upper electrode layer 772 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  FIG. 21 is a schematic sectional view showing a bulk acoustic resonator according to an eighth embodiment of the present invention.

  Referring to FIG. 21, a bulk acoustic resonator 800 according to an eighth embodiment of the present invention includes, for example, a substrate 110, a sacrifice layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 850, a piezoelectric layer 160, and an upper layer. It may include an electrode 170, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 850 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 850 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  As an example, the lower electrode 850 includes a first lower electrode layer 852 and a second lower electrode layer 854 formed on the first lower electrode layer 852 and made of an aluminum alloy material containing scandium (Sc). .

  Meanwhile, the first lower electrode layer 852 may be formed using a conductive material such as Molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto, and the first lower electrode layer 852 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  FIG. 22 is a schematic sectional view showing a bulk acoustic resonator according to a ninth embodiment of the present invention.

  Referring to FIG. 22, a bulk acoustic resonator 900 according to a ninth embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 950, a piezoelectric layer 160, and an upper layer. It may include an electrode 970, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 950 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 950 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  As an example, the lower electrode 950 includes a first lower electrode layer 952 made of an aluminum alloy material containing scandium (Sc), and a second lower electrode layer 954 formed on the first lower electrode layer 952.

  Meanwhile, the second lower electrode layer 954 may be formed using a conductive material such as Molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto, and the second lower electrode layer 954 may include ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), and titanium (Titanium: Ti). And conductive materials such as tantalum (Ta), nickel (Ni), and chromium (Cr), or alloys thereof.

  The upper electrode 970 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 970 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 950 is used as an input electrode, the upper electrode 970 can be used as an output electrode, and when the lower electrode 950 is used as an output electrode, the upper electrode 970 can be used as an input electrode.

  On the other hand, the upper electrode 970 includes a first upper electrode layer 972 and a second upper electrode layer 974 disposed on the first upper electrode layer 972 and made of an aluminum alloy material containing scandium (Sc).

  In addition, the first upper electrode layer 972 may be formed using a conductive material such as molybdenum (Molybdenum: Mo) or an alloy thereof. However, the present invention is not limited thereto, and the first upper electrode layer 972 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  FIG. 23 is a schematic sectional view showing a bulk acoustic resonator according to a tenth embodiment of the present invention.

  Referring to FIG. 23, for example, a bulk acoustic resonator 1000 according to a tenth embodiment of the present invention includes a substrate 110, a sacrificial layer 120, an etch prevention unit 130, a membrane layer 140, a lower electrode 1050, a piezoelectric layer 160, It may include an electrode 1070, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 1050 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 1050 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  Meanwhile, the lower electrode 1050 may be formed using a conductive material such as molybdenum (Mo) or an alloy thereof, for example. However, the present invention is not limited thereto, and the lower electrode 1050 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium ( It can be made of a conductive material such as Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  The upper electrode 1070 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 1070 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 1050 is used as an input electrode, the upper electrode 1070 can be used as an output electrode, and when the lower electrode 1050 is used as an output electrode, the upper electrode 1070 can be used as an input electrode.

  On the other hand, the upper electrode 1070 includes a first upper electrode layer 1072 and a second upper electrode layer 1074 disposed on the first upper electrode layer 1072 and made of an aluminum alloy material containing scandium (Sc).

  In addition, the first upper electrode layer 1072 may be formed using a conductive material such as molybdenum (Molybdenum: Mo) or an alloy thereof. However, the present invention is not limited thereto, and the first upper electrode layer 1072 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  FIG. 24 is a schematic sectional view showing a bulk acoustic resonator according to an eleventh embodiment of the present invention.

  Referring to FIG. 24, a bulk acoustic resonator 1100 according to an eleventh embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etch prevention unit 130, a membrane layer 140, a lower electrode 150, a piezoelectric layer 160, and an upper layer. It may include an electrode 1170, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The upper electrode 1170 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 1170 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 150 is used as an input electrode, the upper electrode 1170 can be used as an output electrode, and when the lower electrode 150 is used as an output electrode, the upper electrode 1170 can be used as an input electrode.

  On the other hand, the upper electrode 1170 includes a first upper electrode layer 1172 made of an aluminum alloy material containing scandium (Sc), and a second upper electrode layer 1174 formed on the first upper electrode layer 1172.

  The second upper electrode layer 1174 may be formed using a conductive material such as molybdenum (Molybdenum: Mo) or an alloy thereof. However, the present invention is not limited thereto. The second upper electrode layer 1174 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  FIG. 25 is a schematic sectional view showing a bulk acoustic resonator according to a twelfth embodiment of the present invention.

  Referring to FIG. 25, a bulk acoustic resonator 1200 according to a twelfth embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 1250, a piezoelectric layer 160, and an upper layer. It may include an electrode 1270, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 1250 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. Further, the lower electrode 1250 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  For example, the lower electrode 1250 includes a first lower electrode layer 1252 made of an aluminum alloy material containing scandium (Sc), and a second lower electrode layer 1254 formed on the first lower electrode layer 1252.

  Meanwhile, the second lower electrode layer 1254 may be formed using a conductive material such as molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto, and the second lower electrode layer 1254 may include ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), and copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  The upper electrode 1270 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 1270 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 1250 is used as an input electrode, the upper electrode 1270 can be used as an output electrode, and when the lower electrode 1250 is used as an output electrode, the upper electrode 1270 can be used as an input electrode.

  Meanwhile, the upper electrode 1270 may be formed using a conductive material such as molybdenum (Mo) or an alloy thereof, for example. However, without being limited to this, the upper electrode 1270 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Irdium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium ( It can be made of a conductive material such as Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  FIG. 26 is a schematic sectional view showing a bulk acoustic resonator according to a thirteenth embodiment of the present invention.

  Referring to FIG. 26, a bulk acoustic resonator 1300 according to a thirteenth embodiment of the present invention includes, as an example, a substrate 110, a sacrificial layer 120, an etch prevention unit 130, a membrane layer 140, a lower electrode 1350, a piezoelectric layer 160, and an upper layer. It may include an electrode 1370, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 1350 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. In addition, the lower electrode 1350 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  For example, the lower electrode 1350 includes a first lower electrode layer 1352 made of an aluminum alloy material containing scandium (Sc), and a second lower electrode layer 1354 formed on the first lower electrode layer 1352.

  Meanwhile, the second lower electrode layer 1354 may be formed using a conductive material such as molybdenum (Mo) or an alloy thereof. However, without being limited to this, the second lower electrode layer 1354 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  The upper electrode 1370 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 1370 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 1350 is used as an input electrode, the upper electrode 1370 can be used as an output electrode, and when the lower electrode 1350 is used as an output electrode, the upper electrode 1370 can be used as an input electrode.

  On the other hand, the upper electrode 1370 includes a first upper electrode layer 1372 made of an aluminum alloy material containing scandium (Sc), and a second upper electrode layer 1374 formed on the first upper electrode layer 1372.

  The second upper electrode layer 1374 may be formed using a conductive material such as Molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto, and the second upper electrode layer 1374 may include ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), and copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  FIG. 27 is a schematic sectional view showing a bulk acoustic resonator according to a fourteenth embodiment of the present invention.

  Referring to FIG. 27, for example, a bulk acoustic resonator 1400 according to a fourteenth embodiment of the present invention includes a substrate 110, a sacrificial layer 120, an etch prevention unit 130, a membrane layer 140, a lower electrode 1450, a piezoelectric layer 160, It may include an electrode 1470, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 1450 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. Further, the lower electrode 1450 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  As an example, the lower electrode 1450 includes a first lower electrode layer 1452 and a second lower electrode layer 1454 formed on the first lower electrode layer 1452 and made of an aluminum alloy material containing scandium (Sc). .

  Meanwhile, the first lower electrode layer 1452 may be formed using a conductive material such as molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto, and the first lower electrode layer 1452 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  The upper electrode 1470 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 1470 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 1450 is used as an input electrode, the upper electrode 1470 can be used as an output electrode, and when the lower electrode 1450 is used as an output electrode, the upper electrode 1470 can be used as an input electrode.

  Meanwhile, the upper electrode 1470 may be formed using a conductive material such as molybdenum (Mo) or an alloy thereof, for example. However, without being limited to this, the upper electrode 1470 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium ( It can be made of a conductive material such as Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  FIG. 28 is a schematic sectional view showing a bulk acoustic resonator according to a fifteenth embodiment of the present invention.

  Referring to FIG. 28, as an example, a bulk acoustic resonator 1500 according to a fifteenth embodiment of the present invention includes a substrate 110, a sacrificial layer 120, an etching prevention unit 130, a membrane layer 140, a lower electrode 1550, a piezoelectric layer 160, and an upper layer. It may include an electrode 1570, an insertion layer 180, a passivation layer 190, and a metal pad 195.

  The lower electrode 1550 is formed on the membrane layer 140, and a part thereof is disposed on the cavity C. Further, the lower electrode 1550 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  For example, the lower electrode 1550 includes a first lower electrode layer 1552, and a second lower electrode layer 1554 formed on the first lower electrode layer 1552 and made of an aluminum alloy material containing scandium (Sc). .

  Meanwhile, the first lower electrode layer 1552 may be formed using a conductive material such as Molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto, and the first lower electrode layer 1552 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  The upper electrode 1570 is formed so as to cover at least the piezoelectric layer 160 disposed above the cavity C. The upper electrode 1570 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 1550 is used as an input electrode, the upper electrode 1570 can be used as an output electrode, and when the lower electrode 1550 is used as an output electrode, the upper electrode 1570 can be used as an input electrode.

  On the other hand, the upper electrode 1570 includes a first upper electrode layer 1572, and a second upper electrode layer 1574 disposed on the first upper electrode layer 1572 and made of an aluminum alloy material containing scandium (Sc).

  In addition, the first upper electrode layer 1572 can be formed using a conductive material such as molybdenum (Molybdenum: Mo) or an alloy thereof. However, the present invention is not limited thereto, and the first upper electrode layer 1572 may be made of ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu). , Titanium (Titanium: Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or an alloy thereof.

  Hereinafter, characteristics of the bulk acoustic resonator according to the first to fifteenth embodiments of the present invention will be described with reference to the following tables.

  The characteristics in each embodiment are realized by a resonator having a size of 125 × 125 μm. On the other hand, the resonance frequency (Fs, Resonator frequency) was set to approximately 5 GHz, and doped aluminum nitride (Doped AlN, AlScN) having a scandium (Sc) content of 6.25 at% was used as the piezoelectric layer.

  A seed layer is formed below the lower electrode, and the seed layer is made of aluminum nitride (AlN) and has a thickness of 500 °. A passivation layer is stacked on the upper electrode, and the passivation layer is made of silicon oxide (SiO) and has a thickness of 1000 °.

  As can be seen from the table below, when the upper electrode and the lower electrode including the aluminum alloy layer containing scandium (Sc) are used, the electrode thickness can be increased, and the insertion loss can be reduced. In particular, when a lower electrode including an aluminum alloy layer containing scandium (Sc) was used, the crystal orientation of the piezoelectric layer (AlScN) could be improved.

  FIG. 29 is a schematic sectional view showing a bulk acoustic resonator according to a sixteenth embodiment of the present invention.

  Referring to FIG. 29, for example, a bulk acoustic resonator 1600 according to a sixteenth embodiment of the present invention includes a substrate 1610, a membrane layer 1620, a lower electrode 1630, a piezoelectric layer 1640, an upper electrode 1650, a passivation layer 1660, and a metal. A pad 1670 may be included.

  The substrate 1610 can be a substrate on which silicon is stacked. For example, a silicon wafer (Silicon Wafer) may be used as the substrate. On the other hand, the substrate 1610 may be provided with a substrate protection layer 1612 disposed to face the cavity C.

  The substrate protection layer 1612 serves to prevent the substrate 1610 from being damaged when the cavity C is formed.

For example, the substrate protection layer 1612 may include at least one of silicon oxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), aluminum oxide (Al ₂ O ₂ ), and aluminum nitride (AlN). , Chemical vapor deposition, RF magnetron sputtering, and evaporation.

The membrane layer 1620 is formed on the sacrificial layer (not shown) to be removed last, and the membrane layer 1620 forms a cavity C together with the substrate protection layer 1612 by removing the sacrificial layer 1680. That is, a sacrifice layer (not shown) is formed on the substrate 1610 to form the cavity C, and then the sacrifice layer is removed to form the cavity C. As the membrane layer 1620, silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), lead zirconate titanate (PZT), A dielectric layer containing any one of gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO) is used. Can be done.

  Meanwhile, a seed layer (not shown) made of aluminum nitride (AlN) may be formed on the membrane layer 1620. That is, the seed layer may be disposed between the membrane layer 1620 and the lower electrode 1630. The seed layer can be formed using a dielectric or a metal having an HCP crystal structure other than aluminum nitride (AlN). For example, when the seed layer is a metal, the seed layer may be formed of titanium (Ti).

  The lower electrode 1630 is formed on the membrane layer 1620. In addition, the lower electrode 1630 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  Meanwhile, the lower electrode 1630 may be made of, for example, an aluminum alloy material containing scandium (Sc). As a result, the mechanical strength is increased, and high power reactive sputtering can be performed. With such evaporation conditions, an increase in surface roughness of the lower electrode 1630 can be suppressed, and highly oriented growth of the piezoelectric layer 1640 can be induced.

  In addition, since scandium (Sc) is included, the chemical resistance of the lower electrode 1630 is increased, and a problem that may occur in the lower electrode made of pure aluminum can be compensated. Process stability can be ensured. Further, oxidation is likely to occur in the lower electrode made of pure aluminum. However, since the lower electrode 1630 is made of an aluminum alloy material containing scandium, chemical resistance to oxidation is improved.

  The piezoelectric layer 1640 is formed so as to cover at least a part of the lower electrode 1630. The piezoelectric layer 1640 is a portion that causes a piezoelectric effect of converting electrical energy into mechanical energy of an elastic waveform, and includes any of aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT). Can be formed by When the piezoelectric layer 1640 is made of aluminum nitride (AlN), the piezoelectric layer 1640 may further include a rare earth metal. For example, the rare earth metal can include at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, the transition metal may include at least one of titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), and niobium (Nb). Further, magnesium (Mg) which is a divalent metal may be contained.

  The upper electrode 1650 is formed so as to cover at least the piezoelectric layer 1640 disposed above the cavity C. The upper electrode 1650 can be used as one of an input electrode and an output electrode for inputting and outputting an electrical signal such as an RF signal. That is, when the lower electrode 1630 is used as an input electrode, the upper electrode 1650 can be used as an output electrode, and when the lower electrode 1630 is used as an output electrode, the upper electrode 1650 can be used as an input electrode.

  Meanwhile, the upper electrode 1650, like the lower electrode 1630, can be made of an aluminum alloy material containing scandium (Sc).

  In addition, the upper electrode 1650 may include an active region, that is, a frame portion 1652 disposed at an edge of a region where the lower electrode 1630, the piezoelectric layer 1640, and the upper electrode 1650 are all overlapped. it can. Frame portion 1652 has a larger thickness than other portions of upper electrode 1650. As an example, the frame unit 1652 plays a role of reflecting a side wave (Lateral Wave) generated at the time of resonance into the active region and confining the resonance energy in the active region.

  The passivation layer 1660 is formed in a region excluding a part of the lower electrode 1630 and a part of the upper electrode 1650. Meanwhile, the passivation layer 1660 serves to prevent the upper electrode 1650 and the lower electrode 1630 from being damaged during the process.

Further, the frequency of the passivation layer 1660 can be adjusted by adjusting the thickness of the passivation layer 1660 by etching in the final step. For the passivation layer 1660, the same material as that used for the membrane layer 1620 can be used. For example, manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), lead zirconate titanate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃₎ ), Titanium oxide (TiO ₂ ), and zinc oxide (ZnO).

  In addition, the metal pad 1670 is formed on a portion of the lower electrode 1630 and the upper electrode 1650 where the passivation layer 1660 is not formed. As an example, the metal pad 1670 is made of a material such as gold (Au), gold-tin (Au-Sn) alloy, copper (Cu), copper-tin (Cu-Sn) alloy, aluminum (Al), and aluminum alloy. Can be. For example, the aluminum alloy can be an aluminum-germanium (Al-Ge) alloy.

  FIG. 30 is a schematic sectional view showing a bulk acoustic resonator according to a seventeenth embodiment of the present invention.

  Referring to FIG. 30, for example, a bulk acoustic resonator 1700 according to a seventeenth embodiment of the present invention includes a substrate 1710, a membrane layer 1720, a lower electrode 1730, a piezoelectric layer 1740, an upper electrode 1750, a passivation layer 1760, and a metal. A pad 1770 can be included.

  The substrate 1710 can be a substrate on which silicon is stacked. For example, a silicon wafer may be used as a substrate. Meanwhile, the substrate 1710 may be provided with a groove 1721 for forming the cavity C.

  The groove 1721 may be formed to be located at the center of the substrate 1710, or may be located below the active region. Here, the active region refers to a region where the lower electrode 1730, the piezoelectric layer 1740, and the upper electrode 1750 are arranged so as to all overlap.

The membrane layer 1720 forms the cavity C together with the substrate 1710. That is, the membrane layer 1720 can be formed to cover the groove 1721 of the substrate 1710. The membrane layer 1720 is made of silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), lead zirconate titanate (PZT), and gallium. A dielectric layer containing any one of arsenic (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO) is used. Can be

  Meanwhile, a seed layer (not shown) made of aluminum nitride (AlN) may be formed on the membrane layer 1720. That is, the seed layer may be disposed between the membrane layer 1720 and the lower electrode 1730. The seed layer can be formed using a dielectric or a metal having an HCP crystal structure other than aluminum nitride (AlN). For example, when the seed layer is a metal, the seed layer may be formed of titanium (Ti).

  The lower electrode 1730 is formed on the membrane layer 1720. In addition, the lower electrode 1730 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  Meanwhile, the lower electrode 1730 may be made of, for example, an aluminum alloy material containing scandium (Sc). As a result, the mechanical strength is increased, and high power reactive sputtering can be performed. With such evaporation conditions, an increase in surface roughness of the lower electrode 1730 can be suppressed, and highly oriented growth of the piezoelectric layer 1740 can be induced.

  In addition, since scandium (Sc) is included, the chemical resistance of the lower electrode 1730 is increased, and a problem that may occur in the lower electrode made of pure aluminum can be compensated. Process stability can be ensured. Furthermore, oxidation is likely to occur in the lower electrode made of pure aluminum. However, when the lower electrode 1730 is made of an aluminum alloy material containing scandium, chemical resistance to oxidation is improved.

  The piezoelectric layer 1740 is formed so as to cover at least a part of the lower electrode 1730. The piezoelectric layer 1740 is a portion that causes a piezoelectric effect of converting electrical energy into mechanical energy of an elastic waveform, and is made of any of aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT). Can be formed by When the piezoelectric layer 1740 is made of aluminum nitride (AlN), the piezoelectric layer 1640 may further include a rare earth metal. For example, the rare earth metal can include at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, the transition metal may include at least one of titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), and niobium (Nb). Further, magnesium (Mg) which is a divalent metal may be contained.

  The upper electrode 1750 is formed so as to cover at least the piezoelectric layer 1740 disposed above the cavity C. The upper electrode 1750 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 1730 is used as an input electrode, the upper electrode 1750 can be used as an output electrode, and when the lower electrode 1730 is used as an output electrode, the upper electrode 1750 can be used as an input electrode.

  Meanwhile, the upper electrode 1750, like the lower electrode 1730, may be made of an aluminum alloy material containing scandium (Sc).

  In addition, the upper electrode 1750 may include a frame 1752 disposed at an edge of the active region. Frame portion 1752 has a larger thickness than other portions of upper electrode 1750. For example, the frame part 1752 plays a role of reflecting a side wave generated at the time of resonance into the active region and confining the resonance energy in the active region.

  The passivation layer 1760 is formed in a region excluding a part of the lower electrode 1730 and a part of the upper electrode 1750. Meanwhile, the passivation layer 1760 serves to prevent the upper electrode 1750 and the lower electrode 1730 from being damaged during the process.

Further, the thickness of the passivation layer 1760 can be adjusted by etching to adjust the frequency in the final process. For the passivation layer 1760, the same material as the material used for the membrane layer 1720 can be used. For example, manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), lead zirconate titanate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃₎ ), Titanium oxide (TiO ₂ ), and zinc oxide (ZnO).

  In addition, the metal pad 1770 is formed in a part of the lower electrode 1630 and the upper electrode 1750 where the passivation layer 1760 is not formed. As an example, the metal pad 1770 is made of a material such as gold (Au), gold-tin (Au-Sn) alloy, copper (Cu), copper-tin (Cu-Sn) alloy, aluminum (Al), and aluminum alloy. Can be. For example, the aluminum alloy can be an aluminum-germanium (Al-Ge) alloy.

  FIG. 31 is a schematic sectional view showing a bulk acoustic resonator according to an eighteenth embodiment of the present invention.

  Referring to FIG. 31, for example, a bulk acoustic resonator 1800 according to an eighteenth embodiment of the present invention includes a substrate 1810, a membrane layer 1820, a lower electrode 1830, a piezoelectric layer 1840, an upper electrode 1850, a passivation layer 1860, and a metal. A pad 1870 may be included.

  The substrate 1810 can be a substrate on which silicon is stacked. For example, a silicon wafer may be used as a substrate. On the other hand, the substrate 1810 may be provided with a reflective layer 1811.

  The reflection layer 1811 may be formed to be disposed at the center of the substrate 1810, or may be disposed below the active region. Here, the active region refers to a region where the lower electrode 1830, the piezoelectric layer 1840, and the upper electrode 1850 are all arranged so as to overlap.

  Meanwhile, the reflection layer 1811 may include first and second reflection members 1812 and 1814 disposed in the groove. The first and second reflecting members 1812 and 1814 may be made of different materials.

The first reflection member 1812 may be formed using a conductive material such as molybdenum (Mo) or an alloy thereof. However, the present invention is not limited thereto, and ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), aluminum (Al), titanium ( Titanium: Ti, tantalum (Tantalum: Ta), nickel (Nickel: Ni), chromium (Chromium: Cr), and the like can be used. The second reflecting member 1814 is made of silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), and lead zirconate titanate ( Dielectric containing any one of PZT), gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO) Layers can be used. Further, the first and second reflecting members 1812 and 1814 may be formed as only one pair, or the first and second reflecting members 1812 and 1814 may be repeatedly formed as a pair.

The membrane layer 1820 can be formed to cover the reflective layer 1811 of the substrate 1810. The membrane layer 1820 is made of silicon nitride (Si ₃ N ₄ ), silicon oxide (SiO ₂ ), manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), lead zirconate titanate (PZT), and gallium. A dielectric layer containing any one of arsenic (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO) is used. Can be

  Meanwhile, a seed layer (not shown) made of aluminum nitride (AlN) may be formed on the membrane layer 1820. That is, the seed layer may be disposed between the membrane layer 1820 and the lower electrode 1830. The seed layer can be formed using a dielectric or a metal having an HCP crystal structure other than aluminum nitride (AlN). For example, when the seed layer is a metal, the seed layer may be formed of titanium (Ti).

  The lower electrode 1830 is formed on the membrane layer 1820. In addition, the lower electrode 1830 can be used as one of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal.

  Meanwhile, the lower electrode 1830 may be made of, for example, an aluminum alloy material containing scandium (Sc). As a result, the mechanical strength is increased, and high power reactive sputtering can be performed. With such evaporation conditions, an increase in surface roughness of the lower electrode 1830 can be suppressed, and highly oriented growth of the piezoelectric layer 1840 can be induced.

  In addition, since scandium (Sc) is included, the chemical resistance of the lower electrode 1830 is increased, and a problem that may occur in the lower electrode made of pure aluminum can be compensated. Process stability can be ensured. Furthermore, oxidation is likely to occur in the lower electrode made of pure aluminum. However, when the lower electrode 1830 is made of an aluminum alloy material containing scandium, chemical resistance to oxidation is improved.

  The piezoelectric layer 1840 is formed so as to cover at least a part of the lower electrode 1830. The piezoelectric layer 1840 is a portion that causes a piezoelectric effect of converting electrical energy into mechanical energy of an elastic waveform, and is made of any of aluminum nitride (AlN), zinc oxide (ZnO), and lead zirconate titanate (PZT). Can be formed by In particular, when the piezoelectric layer 1840 is made of aluminum nitride (AlN), the piezoelectric layer 1840 may further include a rare earth metal. For example, the rare earth metal can include at least one of scandium (Sc), erbium (Er), yttrium (Y), and lanthanum (La). In addition, the transition metal may include at least one of titanium (Ti), zirconium (Zr), hafnium (Hf), tantalum (Ta), and niobium (Nb). Further, magnesium (Mg) which is a divalent metal may be contained.

  The upper electrode 1850 is formed so as to cover at least the piezoelectric layer 1840 disposed above the cavity C. The upper electrode 1850 can be used as any of an input electrode and an output electrode for inputting and outputting an electric signal such as an RF signal. That is, when the lower electrode 1830 is used as an input electrode, the upper electrode 1850 can be used as an output electrode, and when the lower electrode 1830 is used as an output electrode, the upper electrode 1850 can be used as an input electrode.

  Meanwhile, the upper electrode 1850, like the lower electrode 1830, may be made of an aluminum alloy material containing scandium (Sc).

  In addition, the upper electrode 1850 may include a frame 1852 disposed at an edge of the active region. Frame portion 1852 has a larger thickness than other portions of upper electrode 1850. For example, the frame unit 1852 plays a role of reflecting side waves generated at the time of resonance into the active region and confining the resonance energy in the active region.

  The passivation layer 1860 is formed in a region excluding a part of the lower electrode 1830 and a part of the upper electrode 1850. Meanwhile, the passivation layer 1860 serves to prevent the upper electrode 1850 and the lower electrode 1830 from being damaged during the process.

Further, the thickness of the passivation layer 1860 can be adjusted by etching to adjust the frequency in the final process. For the passivation layer 1860, the same material as that used for the membrane layer 1820 can be used. For example, manganese oxide (MgO), zirconium oxide (ZrO ₂ ), aluminum nitride (AlN), lead zirconate titanate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃₎ ), Titanium oxide (TiO ₂ ), and zinc oxide (ZnO).

  In addition, the metal pad 1870 is formed in a part of the lower electrode 1830 and the upper electrode 1850 where the passivation layer 1860 is not formed. As an example, the metal pad 1870 is made of a material such as gold (Au), gold-tin (Au-Sn) alloy, copper (Cu), copper-tin (Cu-Sn) alloy, aluminum (Al), and aluminum alloy. Can be. For example, the aluminum alloy can be an aluminum-germanium (Al-Ge) alloy.

  FIG. 32 is a schematic sectional view showing a bulk acoustic resonator according to a nineteenth embodiment of the present invention.

  Referring to FIG. 32, as an example, a bulk acoustic resonator 1900 according to a nineteenth embodiment of the present invention includes a substrate 1910, a membrane layer 1920, a lower electrode 1950, a piezoelectric layer 1960, an upper electrode 1970, an insertion layer 1980, a passivation layer. 1990 and a metal pad 1995.

  On the other hand, the substrate 1910 and the membrane layer 1920 provided in the bulk acoustic resonator 1900 according to the nineteenth embodiment of the present invention are the same as the components provided in the bulk acoustic resonator 1800 according to the eighteenth embodiment of the present invention. Therefore, the detailed description is omitted here, and the above description is substituted.

  In addition, the lower electrode 1950, the piezoelectric layer 1960, the upper electrode 1970, the insertion layer 1980, the passivation layer 1990 and the metal pad 1995 provided in the bulk acoustic resonator 1900 according to the nineteenth embodiment of the present invention are different from those of the first embodiment of the present invention. Since the same components as the lower electrode 150, the piezoelectric layer 160, the upper electrode 170, the insertion layer 180, the passivation layer 190, and the metal pad 195 provided in the bulk acoustic resonator 100 according to the example, the detailed description is omitted here. Then, the above description is substituted.

The insertion layer 1980 is disposed between the lower electrode 1950 and the piezoelectric layer 1960. The insertion layer 1980 is made of silicon oxide (SiO ₂ ), aluminum nitride (AlN), aluminum oxide (Al ₂ O ₃ ), silicon nitride (Si ₃ N ₄ ), manganese oxide (MgO), zirconium oxide (ZrO ₂ ), titanium It may be made of a dielectric material such as lead zirconate (PZT), gallium arsenide (GaAs), hafnium oxide (HfO ₂ ), aluminum oxide (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), and zinc oxide (ZnO). It can be made of a material different from that of the piezoelectric layer 1960. Further, if necessary, a region in which the insertion layer 1980 is provided can be formed as an empty space, but this can be realized by removing the insertion layer 1980 in a manufacturing process.

  In this embodiment, the thickness of the insertion layer 1980 may be equal to or similar to the thickness of the lower electrode 1950. In addition, the thickness of the piezoelectric layer 1960 may be similar to or smaller than the thickness of the piezoelectric layer 1960. For example, the insertion layer 1980 may be formed to have a thickness of 100 degrees or more, and may be formed to be thinner than the thickness of the piezoelectric layer 1960. However, the configuration of the present invention is not limited to this.

  On the other hand, since the insertion layer 1980 is the same component as the insertion layer 180 provided in the bulk acoustic resonator 100 according to the first embodiment of the present invention, detailed description is omitted here, and the description will be omitted. Substitute.

  Although the embodiments of the present invention have been described in detail, the scope of the present invention is not limited thereto, and various modifications and variations may be made without departing from the technical concept of the present invention described in the claims. It is clear to a person of ordinary skill in the art that is possible.

100, 200, 300, 400, 500, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1800 Bulk acoustic resonator 110 Substrate 120 Sacrificial layer 130 Anti-etching part 140 Membrane Layers 150, 250, 450, 550, 650, 850, 950, 1050, 1250, 1350, 1450, 1550 Lower electrode 160 Piezoelectric layers 170, 370, 570, 670, 770, 970, 1070, 1170, 1270, 1370, 1470, 1570 Upper electrode 180 Insertion layer 190 Passivation layer 195 Metal pad

Claims (22)

Board and
A lower electrode disposed on the substrate,
A piezoelectric layer at least partially disposed on the lower electrode,
An upper electrode disposed on the piezoelectric layer,
Including
At least one of the lower electrode and the upper electrode is seen containing an aluminum alloy layer containing scandium (Sc),
The bulk acoustic resonator , wherein a content of the scandium (Sc) is 0.625 to 5 at% .   The bulk acoustic resonator according to claim 1, wherein each of the lower electrode and the upper electrode includes an aluminum alloy layer containing scandium (Sc).   The upper electrode is made of molybdenum (Molybdenum: Mo), ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium (Titanium). : Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or further includes a layer made of an alloy containing any one of them. The bulk acoustic resonator according to claim 2.   The lower electrode is made of molybdenum (Molybdenum: Mo), ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Irdium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium (Titanium). : Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or further includes a layer made of an alloy containing any one of them. The bulk acoustic resonator according to claim 2. Only the lower electrode includes an aluminum alloy layer containing scandium (Sc),
The upper electrode is made of molybdenum (Molybdenum: Mo), ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium (Titanium). : Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or further includes a layer made of an alloy containing any one of them. The bulk acoustic resonator according to claim 1.   The lower electrode is made of molybdenum (Molybdenum: Mo), ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Irdium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium (Titanium). : Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or further includes a layer made of an alloy containing any one of them. A bulk acoustic resonator according to claim 5. Only the upper electrode includes an aluminum alloy layer containing scandium (Sc),
The lower electrode is made of molybdenum (Molybdenum: Mo), ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Irdium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium (Titanium). : Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or further includes a layer made of an alloy containing any one of them. The bulk acoustic resonator according to claim 1.   The upper electrode is made of molybdenum (Molybdenum: Mo), ruthenium (Ruthenium: Ru), tungsten (Tungsten: W), iridium (Iridium: Ir), platinum (Platinum: Pt), copper (Copper: Cu), titanium (Titanium). : Ti), tantalum (Tantalum: Ta), nickel (Nickel: Ni), and chromium (Chromium: Cr), or further includes a layer made of an alloy containing any one of them. A bulk acoustic resonator according to claim 7. The bulk acoustic resonator according to any one of claims 1 to 8 , wherein the piezoelectric layer is aluminum nitride or doped aluminum nitride containing a rare earth metal. The rare earth metal is one selected from the group consisting of scandium, erbium, yttrium, and lanthanum, or a metal containing a combination thereof, and the content of the element contained in the aluminum nitride is 0.1 to 30 at%. The bulk acoustic resonator according to claim 9 , wherein The bulk acoustic resonator according to any one of claims 1 to 10 , further comprising an anti-etching portion disposed between the substrate and the lower electrode and disposed around a cavity. Further seen containing an insertion layer disposed below of a part of the piezoelectric layer,
The piezoelectric layer includes a piezoelectric portion stacked on an upper surface of the lower electrode, and a bent portion extending outward from the piezoelectric portion,
The insertion layer is disposed between the lower electrode and the bent portion of the piezoelectric layer,
The bulk acoustic resonator according to any one of claims 1 to 11 , wherein a side surface of the insertion layer is formed so as to be thicker as the distance from the piezoelectric portion increases . The bulk acoustic resonator according to claim 12, wherein an inclination angle of the side surface of the insertion layer is 5 ° or more and 70 ° or less.   The bulk acoustic resonator according to claim 1, wherein a cavity is formed on or above the substrate.   The bulk acoustic resonator according to any one of claims 1 to 14, wherein the upper electrode includes a frame disposed on an edge of an active region.   The bulk acoustic resonator according to any one of claims 1 to 15, wherein the substrate is provided with a reflective layer embedded in a groove or laminated on the substrate. The reflection layer includes a first reflection member, and a second reflection member disposed on the first reflection member,
17. The bulk acoustic resonator according to claim 16, wherein the first reflection member and the second reflection member include a pair or a plurality of pairs arranged alternately. A lower electrode including a first lower electrode layer disposed on the substrate, and a second lower electrode layer disposed on the first lower electrode layer;
A piezoelectric layer disposed on the lower electrode,
An upper electrode disposed on the piezoelectric layer,
Including
One of the first lower electrode layer and the second lower electrode layer is formed of an aluminum alloy containing scandium (Sc), and the other of the first lower electrode layer and the second lower electrode layer is , A substance other than an aluminum alloy containing scandium (Sc) is formed ,
The bulk acoustic resonator, wherein a content of the scandium (Sc) in the aluminum alloy is 0.625 to 5 at% . Further comprising an insertion layer disposed below a partial region of the piezoelectric layer,
The piezoelectric layer includes a piezoelectric portion stacked on an upper surface of the lower electrode, and a bent portion extending outward from the piezoelectric portion,
The insertion layer is disposed between the lower electrode and the bent portion of the piezoelectric layer,
20. The bulk acoustic resonator according to claim 18 , wherein a side surface of the insertion layer is formed to have a greater thickness as the distance from the piezoelectric unit increases . The upper electrode is formed of molybdenum (Mo), bulk acoustic resonator according to claim 18 or 19. The upper electrode is formed of an aluminum alloy containing scandium (Sc), bulk acoustic resonator according to claim 18 or 19.   Board and
  A lower electrode disposed on the substrate,
  At least a portion is disposed on the lower electrode, a piezoelectric portion stacked on the upper surface of the lower electrode, and a piezoelectric layer including a bent portion extending outward from the piezoelectric portion,
  An upper electrode disposed on the piezoelectric layer,
  An insertion layer disposed between the lower electrode and the bent portion of the piezoelectric layer;
  Including
  At least one of the lower electrode and the upper electrode includes an aluminum alloy layer containing scandium (Sc),
  A bulk acoustic resonator, wherein a side surface of the insertion layer is formed so as to be thicker as the distance from the piezoelectric portion increases.