Piezoelectric device and method for manufacturing the same

Abstract

To suppress generation of microcracks in a predetermined region of a lower layer ScAlN film.SOLUTION: In a method of manufacturing a piezoelectric device 1, a lower electrode film 14 is formed on an insulating film 12, and then, a lower layer ScAlN film 15 is formed. The lower layer ScAlN film 15 is continuous over both a position above the lower electrode film 14 and a position above a non-electrode region 402 where no lower electrode film 14 is arranged of the insulating film 12. Thereafter, ions are implanted into a predetermined region 151 located above the non-electrode region 402 and located adjacently to the lower electrode film 14 in a direction along an upper surface of the insulating film 12, in the lower layer ScAlN film 15. Then, an intermediate electrode film 16, an upper layer ScAlN film 17, and an upper electrode film 18 are sequentially formed on the lower layer ScAlN film 15.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a piezoelectric device and a method for manufacturing the same. [Background technology]

[0002] Patent Document 1 describes a method for manufacturing a piezoelectric device in which a modified portion is formed by ion implantation or laser light irradiation on a part of a piezoelectric film. This is done to prevent cracks from occurring due to the contraction of the piezoelectric film in the lateral direction along the surface of the piezoelectric film. That is, when a piezoelectric film is formed by a sol-gel method or the like and then fired, the piezoelectric film contracts in the lateral direction, causing cracks to occur in the piezoelectric film. The larger the area of ​​the piezoelectric film, the greater the lateral stress generated in the piezoelectric film, making it more likely to cause cracks. Therefore, by dividing the piezoelectric film into multiple parts in the lateral direction by the modified portion, the stress generated in the lateral direction is divided, and the occurrence of cracks is prevented. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2014-179572 A Summary of the Invention [Problem to be solved by the invention]

[0004] By the way, there is a piezoelectric device that includes a lower electrode film arranged on a support, a lower ScAlN film arranged continuously both above the lower electrode film and above the non-electrode region of the support where the lower electrode film is not arranged, an intermediate electrode film arranged on the lower ScAlN film, an upper ScAlN film arranged on the intermediate electrode film, and an upper electrode film arranged on the upper ScAlN film. In manufacturing a piezoelectric device of this structure, a lower electrode film is formed on the support. Then, a lower ScAlN film is formed continuously both above the lower electrode film and above the non-electrode region of the support. Then, an intermediate electrode film, an upper ScAlN film, and an upper electrode film are formed in order on the lower ScAlN film.

[0005] Here, after the formation of the lower ScAlN film, in a certain region of the lower ScAlN film located on the non-electrode region of the support and adjacent to the lower electrode film in the direction along the upper surface of the support, a state in which a tensile stress is locally generated due to a step caused by the presence or absence of the lower electrode film, or a state in which a compressive stress smaller than that of other regions is generated, is generated. Therefore, the crystallinity of this certain region is worse than that of other regions.

[0006] In this state, when an intermediate electrode film and an upper ScAlN film are formed on the lower ScAlN film, these film stresses are applied to a predetermined region of the lower ScAlN film. This increases the tensile stress that occurred in the predetermined region before the intermediate electrode film and the upper ScAlN film were formed. Alternatively, the small compressive stress that occurred in the predetermined region before the intermediate electrode film and the upper ScAlN film were formed changes to a large tensile stress. If the tensile stress occurring in the predetermined region is large, microcracks occur in the predetermined region. These microcracks become paths (i.e., leak paths) through which current easily flows between the lower electrode film and the intermediate electrode film. For this reason, it is necessary to suppress the occurrence of microcracks.

[0007] In view of the above, an object of the present invention is to provide a piezoelectric device capable of suppressing the occurrence of microcracks in a predetermined region of a lower ScAlN film, and a method for manufacturing the same. [Means for solving the problem]

[0008] In order to achieve the above object, according to the invention described in claim 1, The piezoelectric device is A support (2) having a support body portion (4) and a space portion (5); a lower electrode film (14) disposed above at least the support body portion; a lower layer ScAlN film (15) made of ScAlN, which is disposed above the support body and the space, and is continuous over both a position above the lower electrode film and a position above a non-electrode region (402) of the support body where the lower electrode film is not disposed; an intermediate electrode film (16) disposed above at least a portion of the lower electrode film and laminated on the lower ScAlN film; an upper layer ScAlN film (17) made of ScAlN, which is disposed above the support body and the space, and is laminated on the upper and lower layers of the intermediate electrode film in a region where the intermediate electrode film is not disposed; an upper electrode film (18) disposed above at least a portion of the intermediate electrode film and laminated on the upper layer ScAlN film; A portion (302) of the laminate (3) including the lower ScAlN film and the upper ScAlN film, which is located above the space portion, is a membrane structure, the lower layer ScAlN film is located above a non-electrode region of the support body and has a predetermined region (151, 151A, 151B, 151C, 151D) located next to the lower electrode film in a direction along the upper surface of the support body; The concentration of the predetermined element in the predetermined region is higher than that of the membrane region (152) constituting the membrane structure in the lower ScAlN film. And, The predetermined element is Al, Sc, N, or an element of the same group, or a rare gas, or oxygen. .

[0009] This piezoelectric device is manufactured by implanting ions into a predetermined region of the lower ScAlN film. When manufacturing the piezoelectric device, compressive stress can be applied to the predetermined region by implanting ions into the predetermined region of the lower ScAlN film. Therefore, by forming an intermediate electrode film and an upper ScAlN film on the lower ScAlN film, even if tensile stress is applied to the lower ScAlN film, the state in which compressive stress is generated in the predetermined region can be maintained. Or, even if tensile stress is generated in the predetermined region, the value of the tensile stress can be reduced. Therefore, the occurrence of microcracks in the predetermined region of the lower ScAlN film can be suppressed.

[0010] In addition, claims 5 According to the invention described in A method for manufacturing a piezoelectric device includes the steps of: forming a lower electrode film (14) on a support (2); forming a lower layer ScAlN film (15) made of ScAlN, the lower layer ScAlN film (15) being continuous over both a position above the lower electrode film and a position above a non-electrode region (402) of the support where the lower electrode film is not disposed; forming an intermediate electrode film (16) on the lower ScAlN film; Before or after the formation of the intermediate electrode film, ions are implanted into a predetermined region (151, 151A, 151B, 151C, 151D) of the lower ScAlN film located above a non-electrode region and adjacent to the lower electrode film in a direction along the upper surface of the support; forming an upper layer ScAlN film (17) made of ScAlN on a region of the upper layer ScAlN film and the lower layer ScAlN film where the intermediate electrode film is not disposed; and forming an upper electrode film (18) on the upper ScAlN film.

[0011] According to this, compressive stress can be applied to a predetermined region of the lower ScAlN film by implanting ions into the predetermined region. Therefore, by forming an intermediate electrode film and an upper ScAlN film on the lower ScAlN film, even if tensile stress is applied to the lower ScAlN film, the state in which compressive stress is generated in the predetermined region can be maintained. Or, even if tensile stress is generated in the predetermined region, the value of the tensile stress can be reduced. Therefore, the occurrence of microcracks in the predetermined region of the lower ScAlN film can be suppressed.

[0012] In addition, claims 11 According to the invention described in A method for manufacturing a piezoelectric device includes the steps of: forming a lower electrode film (14) on a support (2); forming a lower layer ScAlN film (15) made of ScAlN, the lower layer ScAlN film (15) being continuous over both a position above the lower electrode film and a position above a non-electrode region (402) of the support where the lower electrode film is not disposed; Irradiating a laser beam (La) to a predetermined region (151E) of the lower layer ScAlN film, the region being located above a non-electrode region and adjacent to the lower electrode film in a direction along the upper surface of the support, to heat the region; forming an intermediate electrode film (16) on the lower ScAlN film after the irradiation of the laser light; forming an upper layer ScAlN film (17) made of ScAlN on a region of the upper layer ScAlN film and the lower layer ScAlN film where the intermediate electrode film is not disposed; and forming an upper electrode film (18) on the upper ScAlN film.

[0013] According to this, compressive stress can be applied to a predetermined region of the lower ScAlN film by locally heating the predetermined region. Therefore, even if tensile stress is applied to the lower ScAlN film by forming an intermediate electrode film and an upper ScAlN film on the lower ScAlN film, the state in which compressive stress is generated in the predetermined region can be maintained. Or, even if tensile stress is generated in the predetermined region, the value of the tensile stress can be reduced. Therefore, the occurrence of microcracks in the predetermined region of the lower ScAlN film can be suppressed.

[0014] Note that the reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0015] [Figure 1] 1 is a cross-sectional view of a piezoelectric device according to a first embodiment. [Diagram 2] FIG. 2 is an enlarged view of part II in FIG. [Diagram 3] 3A to 3C are cross-sectional views illustrating a manufacturing process of the piezoelectric device according to the first embodiment. [Figure 4] 4A to 4C are cross-sectional views showing a manufacturing process of the piezoelectric device following FIG. 3. [Diagram 5] 5A to 5C are cross-sectional views showing a manufacturing process of the piezoelectric device following FIG. 4. [Figure 6] 6A to 6C are cross-sectional views showing a manufacturing process of the piezoelectric device subsequent to FIG. 5. [Figure 7] 4 is a cross-sectional view of a portion of a piezoelectric device of Comparative Example 1. FIG. [Figure 8] 5A to 5C are cross-sectional views illustrating a manufacturing process of the piezoelectric device according to the second embodiment. [Figure 9] 9A to 9C are cross-sectional views showing a manufacturing process of the piezoelectric device subsequent to FIG. 8. [Figure 10] 10A to 10C are cross-sectional views showing a manufacturing process of the piezoelectric device subsequent to FIG. [Figure 11] 10A to 10C are cross-sectional views illustrating a manufacturing process of the piezoelectric device according to the third embodiment. [Figure 12] 10A to 10C are cross-sectional views illustrating a manufacturing process of the piezoelectric device according to the fourth embodiment. [Figure 13] 13A to 13C are cross-sectional views illustrating a manufacturing process for the piezoelectric device according to the fifth embodiment. [Figure 14] 13A to 13C are cross-sectional views illustrating a manufacturing process for the piezoelectric device according to the sixth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other will be denoted by the same reference numerals.

[0017] (First embodiment) 1, a piezoelectric device 1 according to the present embodiment is used as a microphone. The piezoelectric device 1 includes a support 2 and a piezoelectric film laminate 3.

[0018] The support 2 supports the piezoelectric film laminate 3. The support 2 has a support main body 4 and a space 5. The support main body 4 includes a substrate 11 and an insulating film 12 arranged on the substrate 11. The substrate 11 is made of silicon (Si) or the like. The insulating film 12 is made of an insulating material such as silicon oxide. The upper surface of the insulating film 12 forms the upper surface of the support main body 4. The space 5 is arranged in the center of the support 2.

[0019] The piezoelectric film laminate 3 is supported by the support body 4. The piezoelectric film laminate 3 is disposed over both the support body 4 and the space 5. A fixed portion 301, which is a portion of the piezoelectric film laminate 3 located above the support body 4, is fixed to the support body 4. A floating portion 302, which is a portion of the piezoelectric film laminate 3 located above the space 5, is in a floating state. The floating portion 302 is a membrane structure that is thinner than other regions. A slit 303 is formed in the floating portion 302. Therefore, the end of the floating portion 302 away from the support body 4 is a free end that is not fixed. The end of the floating portion 302 on the support body 4 side is a fixed end that is fixed. In this way, the floating portion 302 is a cantilever (i.e., a cantilever structure in which one end is a free end and the other end is a fixed end).

[0020] 1 and 2, the piezoelectric film laminate 3 is formed by laminating a plurality of films including a piezoelectric film. Specifically, the piezoelectric film laminate 3 includes, as the plurality of films, an AlN film 13, a lower electrode film 14, a lower layer ScAlN film 15, an intermediate electrode film 16, an upper layer ScAlN film 17, and an upper electrode film 18.

[0021] The AlN film 13 is a film made of AlN (i.e., aluminum nitride). The AlN film 13 is a buffer film used to improve the crystallinity of the material making up the lower electrode film 14 and the lower ScAlN film 15 formed on the AlN film 13. The lower electrode film 14 is a metal film made mainly of Mo. The lower electrode film 14 may be made of a metal material containing a metal element other than Mo.

[0022] The AlN film 13 and the lower electrode film 14 are disposed above the support body 4 and the space 5. A portion of the AlN film 13 located above the support body 4 is in contact with the upper surface of the support body 4. The lower electrode film 14 is in contact with the upper surface of the AlN film 13 and laminated on the AlN film 13. The lower electrode film 14 and the AlN film 13 have the same predetermined planar pattern.

[0023] The AlN film 13 and the lower electrode film 14 are disposed continuously from a position above the support body 4 to the position of the tip, which is the free end, of the piezoelectric film stack 3. However, the AlN film 13 and the lower electrode film 14 may be disposed above the space 5 on the support body 4 side of the tip, which is the free end, of the piezoelectric film stack 3.

[0024] Also, as shown on the left side of Figure 1, a portion of the AlN film 13 and the lower electrode film 14 is located above the support body 4 and farther from the space 5 than the intermediate electrode film 16 and the upper electrode film 18, and is connected to a first contact via 212 described later.

[0025] 2, the ends of the AlN film 13 and the lower electrode film 14 are located above the support body 4. Therefore, the support body 4 has an electrode region 401 above which the AlN film 13 and the lower electrode film 14 are arranged, and a non-electrode region 402 above which the AlN film 13 and the lower electrode film 14 are not arranged.

[0026] The lower layer ScAlN film 15 is a piezoelectric film made of polycrystalline ScAlN (i.e., scandium-containing aluminum nitride). Made of ScAlN means that the main component is ScAlN, and the lower layer ScAlN film 15 may contain components other than ScAlN. As shown in FIG. 1, the lower layer ScAlN film 15 is disposed above the support body 4 and the space 5. At a position above the space 5, the lower layer ScAlN film 15 is in contact with the upper surface of the lower electrode film 14. As shown in FIG. 2, at a position above the support body 4, the lower layer ScAlN film 15 is continuous over both a position above the lower electrode film and a position above the non-electrode region 402 of the support body 4. More specifically, the lower layer ScAlN film 15 is in contact with and continuous with both the upper surface of the lower electrode film 14 and the upper surface of the non-electrode region 402 of the support body 4.

[0027] The intermediate electrode film 16 is a metal film mainly composed of Mo. The intermediate electrode film 16 may be composed of a metal material containing a metal element other than Mo. As shown in FIG. 1, the intermediate electrode film 16 is disposed above both the support body 4 and the space 5. The intermediate electrode film 16 is disposed above at least a part of the lower electrode film 14. The intermediate electrode film 16 is in contact with the upper surface of the lower ScAlN film 15 and is laminated on the lower ScAlN film 15. The intermediate electrode film 16 may be laminated on the lower ScAlN film 15 via another film.

[0028] 1, a part of the intermediate electrode film 16 faces a part of the lower electrode film 14 in the thickness direction of the lower ScAlN film 15, sandwiching the lower ScAlN film 15. Also, as shown on the right side of FIG. 1, another part of the intermediate electrode film 16 is located above the support body 4 and farther from the space 5 than the lower electrode film 14 and the upper electrode film 18, and is connected to a second contact via 222 described later.

[0029] The intermediate electrode film 16 extends continuously from a position above the support body 4 to the position of the tip, which is the free end, of the piezoelectric film laminate 3. However, the intermediate electrode film 16 may be disposed above the space 5 on the support body 4 side of the tip, which is the free end, of the piezoelectric film laminate 3.

[0030] The upper layer ScAlN film 17 is a piezoelectric film made of polycrystalline ScAlN. Made of ScAlN means that the main component is ScAlN, and the upper layer ScAlN film 17 may contain components other than ScAlN. The upper layer ScAlN film 17 is disposed above both the support body 4 and the space 5. The upper layer ScAlN film 17 is laminated above the intermediate electrode film 16 and above a region of the lower layer ScAlN film 15 where the intermediate electrode film 16 is not disposed.

[0031] The upper electrode film 18 is a metal film mainly composed of Mo. The upper electrode film 18 may be composed of a metal material containing a metal element other than Mo. The upper electrode film 18 is disposed above both the support body 4 and the space 5. The upper electrode film 18 is disposed above at least a part of the intermediate electrode film 16. A part of the upper electrode film 18 faces a part of the intermediate electrode film 16 with the upper ScAlN film 17 in between. The upper electrode film 18 is in contact with the upper surface of the upper ScAlN film 17 and is laminated on the upper ScAlN film 17. The upper electrode film 18 may be laminated on the upper ScAlN film 17 via another film.

[0032] The upper electrode film 18 is disposed continuously from a position above the support body 4 to the position of the tip, which is the free end, of the piezoelectric film stack 3. However, the upper electrode film 18 may be disposed above the space 5 on the support body 4 side of the tip, which is the free end, of the piezoelectric film stack 3.

[0033] 1, the piezoelectric device 1 includes a protective film 20 covering a part of the piezoelectric film laminate 3, a lower contact electrode portion 21 connected to the lower electrode film 14, and an intermediate contact electrode portion 22 connected to the intermediate electrode film 16. The protective film 20 is disposed above the support body portion 4.

[0034] The lower contact electrode portion 21 is disposed above the support body portion 4. The lower contact electrode portion 21 includes a first contact via 212 provided in a first through hole 211 penetrating the protective film 20, the upper ScAlN film 17, and the lower ScAlN film 15, and a first wiring 213 provided on the protective film 20 and connected to the first contact via 212.

[0035] The intermediate contact electrode portion 22 is disposed above the support body portion 4 at a position different from the position at which the lower contact electrode portion 21 is disposed. The intermediate contact electrode portion 22 includes a second contact via 222 provided in a second through hole 221 penetrating the protective film 20 and the upper ScAlN film 17, and a second wiring 223 provided on the protective film 10 and connected to the second contact via 222.

[0036] Next, a method for manufacturing the piezoelectric device 1 having the above-mentioned structure will be described. As shown in Fig. 3, a lower electrode film 14 having a predetermined planar shape is formed on an insulating film 12 constituting the support 2. Fig. 3 is a cross-sectional view of the support 2, the lower electrode film 14, etc., at a portion corresponding to Fig. 2, and the substrate 11 is omitted.

[0037] Specifically, an insulating film 12 is formed on a substrate 11 (not shown). Then, an AlN film 13 and a lower electrode film 14 are formed in this order on the insulating film 12. Then, both the lower electrode film 14 and the AlN film 13 are patterned into the same planar shape by photolithography and etching. The ends of the lower electrode film 14 and the AlN film 13 are located on the insulating film 12. Therefore, the insulating film 12 has an electrode region 401 where the AlN film 13 and the lower electrode film 14 are arranged, and a non-electrode region 402 where the AlN film 13 and the lower electrode film 14 are not arranged.

[0038] 4, the lower layer ScAlN film 15 is formed on the lower electrode film 14. At this time, the lower layer ScAlN film 15 is formed continuously over both a position above the lower electrode film 14 and a position above the non-electrode region 402 of the insulating film 12. More specifically, the lower layer ScAlN film 15 is formed continuously in contact with both the upper surface of the lower electrode film 14 and the upper surface of the non-electrode region 402 of the insulating film 12.

[0039] After the formation of the lower ScAlN film 15 is completed, ions are implanted into the lower ScAlN film 15 as shown in Fig. 5. After the formation is completed means that the lower ScAlN film 15 has been formed to the intended thickness.

[0040] At this time, if ions are implanted into the entire lower ScAlN film 15, the stress design of the floating part 302 in FIG. 1, which is the cantilever, will collapse. Therefore, a resist mask 31 is formed to cover the lower ScAlN film 15 except for a predetermined region 151. As a result, ions are not implanted into the region of the lower ScAlN film 15 that constitutes the floating part 302 in FIG. 1, but are implanted into the predetermined region 151 of the lower ScAlN film 15. This predetermined region 151 is a region of the lower ScAlN film 15 that is located on the non-electrode region 402 of the insulating film 12 and is located next to the lower electrode film 14 in the direction along the upper surface of the insulating film 12. More specifically, this predetermined region 151 is a region from the end of the lower electrode film 14 to a predetermined distance D1 that is equal to or less than the thickness T1 of the lower ScAlN film 15.

[0041] Furthermore, if the implanted elements are activated by a heat treatment in a subsequent process, the insulation resistance of the lower ScAlN film 15 decreases, leading to the lower ScAlN film 15 becoming conductive. Therefore, Al, Sc, N, or elements of the same group, or rare gas, or oxygen, are used as the ion species. This makes it possible to suppress the decrease in the insulation resistance of the lower ScAlN film 15. Note that, although one ion species is used in this embodiment, multiple ion species may be used. After the ion implantation, the resist mask 31 is removed.

[0042] 6, an intermediate electrode film 16 having a predetermined planar shape is formed on the lower ScAlN film 15. The intermediate electrode film 16 is disposed above at least a part of the lower electrode film 14. An upper ScAlN film 17 is then formed on the intermediate electrode film 16. The upper ScAlN film 17 is disposed above the intermediate electrode film 16 and above a region of the lower ScAlN film 15 where the intermediate electrode film 16 is not formed. The upper ScAlN film 17 is disposed from a position above the lower electrode film 14 to a position above the non-electrode region 402 of the insulating film 12. An upper electrode film 18 having a predetermined planar shape is then formed on the upper ScAlN film 17. The upper electrode film 18 is disposed above at least a part of the intermediate electrode film 16.

[0043] Thereafter, although not shown, the slits 303 are formed in the piezoelectric film laminate 3 by photolithography and etching. Also, although not shown, the support 2 is subjected to photolithography and etching to form the space 5 in the support 2. Note that the timing of forming the slits 303 and the space 5 can be changed.

[0044] In this manner, the piezoelectric device 1 of this embodiment is manufactured. As described above, in the method for manufacturing the piezoelectric device 1 of this embodiment, ions are implanted into the predetermined region 151 of the lower ScAlN film 15. Therefore, in the manufactured piezoelectric device 1, the concentration of the predetermined element in the predetermined region 151 of the lower ScAlN film 15 shown in FIG. 2 is higher than that in the cantilever region 152 constituting the cantilever of the lower ScAlN film 15 shown in FIG. 1. The predetermined element to be compared is the same element. The predetermined element is any one of the ion species described above. The cantilever region 152 corresponds to the membrane region constituting the membrane structure.

[0045] Next, the effects of this embodiment will be described in comparison with a piezoelectric device J1 of Comparative Example 1 shown in Fig. 7. The manufacturing method of the piezoelectric device J1 of Comparative Example 1 differs from this embodiment in that the piezoelectric device J1 is manufactured without implanting ions into the lower ScAlN film 15. The manufacturing method of the piezoelectric device J1 and other configurations of the piezoelectric device J1 are the same as those of the piezoelectric device 1 and the piezoelectric device 1 of this embodiment.

[0046] When the piezoelectric device J1 is manufactured by the manufacturing method of Comparative Example 1, in the formation of the lower ScAlN film 15, a tensile stress is locally generated in the predetermined region 151Z of the lower ScAlN film 15 due to a step caused by the presence or absence of the lower electrode film 14, or a compressive stress smaller than that in other regions is generated. Therefore, the crystallinity of the predetermined region 151Z is worse than that of the other regions. The predetermined region 151Z is the same location as the predetermined region 151 of this embodiment.

[0047] In this state, when the intermediate electrode film 16 and the upper ScAlN film 17 are formed in sequence on the lower ScAlN film 15 from a position above the lower electrode film 14 to a position above the non-electrode region 402, these film stresses are applied to the predetermined region 151Z of the lower ScAlN film 15. As a result, the tensile stress generated in the predetermined region 151Z before the intermediate electrode film 16 and the upper ScAlN film 17 are formed increases. Alternatively, the small compressive stress generated in the predetermined region 151Z before the intermediate electrode film 16 and the upper ScAlN film 17 are formed changes to a large tensile stress. If the tensile stress generated in the predetermined region 151Z is large, a microcrack C1 is generated in the predetermined region 151Z. This microcrack C1 can become a path (i.e., a leak path) through which a current easily flows between the lower electrode film 14 and the intermediate electrode film 16. For this reason, when the microcrack C1 is generated, the dielectric loss of the capacitance formed between the lower electrode film 14 and the intermediate electrode film 16 increases. This leads to noise in the microphone, degrading its performance.

[0048] In contrast, the method for manufacturing the piezoelectric device 1 of this embodiment includes implanting ions into the predetermined region 151 of the lower ScAlN film 15 after the lower ScAlN film 15 is formed and before the intermediate electrode film 16 is formed.

[0049] According to this, by implanting ions into the predetermined region 151 of the lower ScAlN film 15, compressive stress can be applied to the predetermined region 151. Therefore, by forming the intermediate electrode film 16 and the upper ScAlN film 17 on the lower ScAlN film 15, even if tensile stress is applied to the lower ScAlN film 15, the state in which compressive stress is generated in the predetermined region 151 can be maintained. Or, even if tensile stress is generated in the predetermined region 151, the value of the tensile stress can be reduced. Therefore, the generation of microcracks C1 in the predetermined region 151 of the lower ScAlN film 15 can be suppressed.

[0050] Here, an example of the amount of ions implanted to apply compressive stress to the predetermined region 151 will be mentioned. According to the results of experiments conducted by the present inventors, the concentration of implanted ions in the film is 1×1018 atms / cm 3 A stress shift of about 100 MPa was obtained. For example, this is expressed as an ion implantation dose for a film with a thickness of 500 nm, which is 5×10 13 atms / cm 2 It is also known that the amount of stress shift is roughly proportional to the concentration of the implanted ions in the film. The above experimental results are for implanting Si and Mg, respectively, and there is no significant difference between the two. Therefore, it can be said that similar results can be obtained by implanting Sc or Al ions, which are intermediate in terms of ion radius.

[0051] Furthermore, in the piezoelectric device 1 of this embodiment, the concentration of the predetermined element in the predetermined region 151 of the lower ScAlN film 15 is higher than that in the cantilever region 152 of the lower ScAlN film 15. This is achieved by the above-mentioned ion implantation into the predetermined region 151. That is, the piezoelectric device 1 of this embodiment is manufactured by the above-mentioned method for manufacturing the piezoelectric device 1. Therefore, according to the piezoelectric device 1 of this embodiment, the same effects as those of the above-mentioned method for manufacturing the piezoelectric device 1 can be obtained.

[0052] In the manufacturing method of this embodiment, ions are not implanted into the cantilever region 152 of the lower ScAlN film 15, but some ion implantation may be performed for the purpose of controlling the stress of the cantilever. Even in this case, the concentration of a predetermined element in a predetermined region 151 of the lower ScAlN film 15 is higher than that in the cantilever region 152 of the lower ScAlN film.

[0053] In the manufacturing method of this embodiment, Al, Sc, N, elements of the same group, rare gas, or oxygen is used as the ion species in the ion implantation into the predetermined region 151 of the lower ScAlN film 15. However, in cases where no heat treatment is performed after the ion implantation or where a decrease in the insulation resistance of the lower ScAlN film 15 is acceptable, other elements may be used as the ion species.

[0054] 2 of the piezoelectric device 1 of this embodiment, the intermediate electrode film 16 is disposed from a position above the lower electrode film 14 to a position above the non-electrode region 402 for connection with the intermediate contact electrode portion 22. However, in the portion of the piezoelectric device 1 other than that shown in FIG. 2, the intermediate electrode film 16 only needs to be disposed above the lower electrode film 14, and does not have to be disposed above the non-electrode region 402. Even in this case, when the upper ScAlN film 17 is formed in the manufacture of the piezoelectric device 1, at least the film stress of the upper ScAlN film 17 is applied to the predetermined region 151 of the lower ScAlN film 15, causing the problem of the piezoelectric device J1 of Comparative Example 1.

[0055] Second embodiment This embodiment differs from the first embodiment in that, in the method for manufacturing the piezoelectric device 1, ions are implanted into the lower ScAlN film 15 during the formation of the lower ScAlN film 15. Specifically, after the lower electrode film 14 is patterned into a predetermined planar shape, as shown in FIG. 8, the formation of the lower ScAlN film 15 is interrupted when the lower ScAlN film 15 is formed. At this time, the thickness T2 of the lower ScAlN film 15 during its formation is smaller than the final thickness T3. For example, the final thickness T3 is 500 nm, and the thickness T2 during its formation is 250 nm.

[0056] 9, ions are implanted into a predetermined region 151A of the lower ScAlN film 15 in the process of being formed. The predetermined region 151A has the same range in the direction along the upper surface of the insulating film 12 as the predetermined region 151 in the first embodiment. This ion implantation is performed by the same method as the ion implantation in the first embodiment, using a resist mask 32. The resist mask 32 is formed in the same position as the resist mask 31.

[0057] 10, the deposition of the lower ScAlN film 15 is resumed, and the lower ScAlN film 15 is deposited to a final thickness T3, thereby forming the lower ScAlN film 15.

[0058] In this embodiment, ion implantation is not performed on the portion of the lower ScAlN film 15 that is grown to the final film thickness after film formation is resumed. Therefore, in the manufactured piezoelectric device 1, the concentration of the predetermined element in a lower portion of the predetermined region 151 of the lower ScAlN film 15 that is located on the lower side is higher than that in an upper portion of the predetermined region 151 that is located above the lower portion. The lower portion corresponds to the ion-implanted predetermined region 151A.

[0059] Other configurations of the manufacturing method of the piezoelectric device 1 and other configurations of the piezoelectric device 1 are the same as those of the first embodiment. This embodiment also provides the same effects as those of the first embodiment. Furthermore, this embodiment also provides the following effects.

[0060] Unlike the present embodiment, when ions are implanted into the lower ScAlN film 15 having the final film thickness T3, it is necessary to increase the acceleration voltage in order to implant ions into the lower portion of the lower ScAlN film 15. If the acceleration voltage is increased, the amount of ions passing through the upper portion of the lower ScAlN film 15 increases, which may deteriorate the crystallinity of the upper portion and increase the leakage current.

[0061] In contrast, according to the present embodiment, since ions are implanted into the lower ScAlN film 15 in the process of being formed, it is not necessary to increase the acceleration voltage. Also, deterioration of the crystallinity of the upper portion due to the passage of ions can be avoided.

[0062] In this embodiment, ion implantation is performed once during the formation of the lower ScAlN film 15, but ion implantation may be performed multiple times. That is, the formation of the lower ScAlN film 15 may be interrupted multiple times, and ion implantation may be performed after each interruption.

[0063] Third embodiment In this embodiment, an ion implantation step is added to the method for manufacturing the piezoelectric device 1 of the second embodiment. Specifically, as in the second embodiment, as shown in FIG. 10, after the ion implantation, the formation of the lower ScAlN film 15 is resumed, and the lower ScAlN film 15 is formed to a final thickness T3. Thereafter, unlike the second embodiment, as shown in FIG. 11, ion implantation is performed on a predetermined region 151B of the lower ScAlN film 15 that has been increased to the final thickness. The range of this predetermined region 151B in the direction along the upper surface of the insulating film 12 is the same as that of the predetermined region 151 of the first embodiment. This ion implantation is performed by using a resist mask 33 in the same manner as the ion implantation in the first embodiment. The resist mask 33 is formed at the same position as the resist mask 31.

[0064] At this time, the concentration of the predetermined element in an upper portion of predetermined region 151 (i.e., predetermined region 151B) is set to be the same as the concentration of the predetermined element in a lower portion of predetermined region 151 (i.e., predetermined region 151A), or is set to be lower than the concentration of the predetermined element in the lower portion of predetermined region 151. Note that the concentration of the predetermined element in the upper portion of predetermined region 151 may be set to be higher than the concentration of the predetermined element in the lower portion of predetermined region 151.

[0065] In this way, ions may be implanted into the lower ScAlN film 15 during the formation of the lower ScAlN film 15 and after the completion of the formation of the lower ScAlN film 15. This embodiment also provides the same effects as the second embodiment.

[0066] (Fourth embodiment) As shown in FIG. 12, in this embodiment, when ions are implanted into the lower ScAlN film 15, the amount of ions implanted into the lower portion 151C2 located below the upper portion 151C1 of the predetermined region 151C is smaller than the amount of ions implanted into the upper portion 151C1 located at the upper side of the predetermined region 151C. This predetermined region 151C is in the same range as the predetermined region 151 in the first embodiment. Therefore, in the manufactured piezoelectric device 1, the concentration of the predetermined element in the lower portion 151C2 is lower than that in the upper portion 151C1. The lower portion 151C2 is preferably a portion having a thickness T4 of 100 nm from the lower end of the lower ScAlN film 15. Other configurations of the manufacturing method of the piezoelectric device 1 and other configurations of the piezoelectric device 1 are the same as those of the first embodiment.

[0067] In forming the lower ScAlN film 15, the film is likely to be in a state in which compressive stress is applied in the early stage of growth. Therefore, it is not necessary to implant ions into the lower portion 151C2 of the predetermined region 151C, particularly into the portion having a thickness T4 of 100 nm from the lower end of the lower ScAlN film 15. By implanting ions into the upper portion 151C1, the same effect as in the first embodiment can be obtained.

[0068] The lower portion 151C2 is preferably a portion having a thickness T4 of 100 nm from the lower end of the lower ScAlN film 15, but is not limited to this. The thickness T4 of the lower portion 151C2 from the lower end of the lower ScAlN film 15 may be greater than 100 nm.

[0069] Fifth embodiment 13, in this embodiment, ions are implanted into the lower ScAlN film 15 to make the entire predetermined region 151D amorphous. This predetermined region 151D is the same range as the predetermined region 151 in the first embodiment. At this time, the ion implantation amount and implantation depth for making the film amorphous are set to 1×10 20 atoms / cm 3 Therefore, in the manufactured piezoelectric device 1, the entire predetermined region 151D is amorphous.

[0070] Other configurations of the manufacturing method of the piezoelectric device 1 and other configurations of the piezoelectric device 1 are the same as those of the first embodiment. This embodiment also provides the same effects as those of the first embodiment. Furthermore, this embodiment provides the following effects.

[0071] When the predetermined region 151D of the lower ScAlN film 15 is in a polycrystalline state, there is a possibility that a leak path will be formed at the grain boundary. In contrast, according to this embodiment, the predetermined region 151D is in an amorphous state and there is no grain boundary, so that the formation of a leak path can be avoided.

[0072] In the present embodiment, the entirety of the predetermined region 151D is made amorphous by ion implantation in the method for manufacturing the piezoelectric device 1, but only a portion of the predetermined region 151D may be made amorphous. Even in this case, the above-mentioned effects can be obtained in the portion of the predetermined region 151D that is in an amorphous state.

[0073] As described above, in the method for manufacturing the piezoelectric device 1, at least a portion of the predetermined region 151D may be made amorphous by ion implantation. In the piezoelectric device 1, it is sufficient that at least a portion of the predetermined region 151D is amorphous. In the second to fourth embodiments, at least a portion of the predetermined regions 151A, 151B, and 151C may be made amorphous.

[0074] Sixth embodiment 14, in this embodiment, in the method for manufacturing the piezoelectric device 1 of the first embodiment, after forming the lower ScAlN film 15, instead of implanting ions into the predetermined region 151 of the lower ScAlN film 15, a predetermined region 151E of the lower ScAlN film 15 is irradiated with laser light La to heat it. The predetermined region 151E is the same range as the predetermined region 151 of the first embodiment.

[0075] The heating temperature of the predetermined region 151E at this time is set to a temperature at which compressive stress can be applied to the predetermined region 151E. Such a temperature is, for example, 600° C. or higher. In order to prevent deterioration of the crystallinity of ScAlN, the heating temperature is preferably 1000° C. or lower.

[0076] Commercially available laser processing machines such as CO2, fiber, etc. can be used as the laser processing machine that irradiates the laser light La. However, since the shorter the wavelength of the laser light, the smaller the beam diameter can be made and the easier it is to limit the temperature rise area, it is preferable to use a laser processing machine that irradiates a laser light with a short wavelength.

[0077] When the laser light La is irradiated and heated, the cantilever region 152 of the lower ScAlN film 15 shown in FIG. 1 is not heat-treated.

[0078] After irradiation with the laser light La, an intermediate electrode film 16 is formed on the lower ScAlN film 15. The other steps in the method for manufacturing the piezoelectric device 1 are the same as those in the first embodiment. The configuration of the piezoelectric device 1 is the same as that in the first embodiment.

[0079] According to the manufacturing method of the piezoelectric device 1 of this embodiment, compressive stress can be applied to the predetermined region 151E by locally heating the predetermined region 151E of the lower ScAlN film 15. Therefore, by forming the intermediate electrode film 16 and the upper ScAlN film 17 on the lower ScAlN film 15, even if tensile stress is applied to the lower ScAlN film 15, the state in which compressive stress is generated in the predetermined region 151E can be maintained. Or, even if tensile stress is generated in the predetermined region 151E, the value of the tensile stress can be reduced. Therefore, the occurrence of microcracks in the predetermined region 151E of the lower ScAlN film 15 can be suppressed. (Other embodiments)

[0080] (1) In the first to fifth embodiments, ion implantation into the lower ScAlN film 15 is performed before the intermediate electrode film 16 is formed. However, ion implantation into the lower ScAlN film 15 may be performed after the intermediate electrode film 16 is formed. In this case, ions are implanted through the intermediate electrode film 16.

[0081] (2) In each of the above-described embodiments, the support body 4 includes the substrate 11 and the insulating film 12. However, the support body 4 may not include the insulating film 12 and may be composed of only the substrate 11. Furthermore, the support body 4 may include other members in addition to the substrate 11 and the insulating film 12.

[0082] (3) In each of the above-described embodiments, the lower electrode film 14 is disposed above the support body 4 via the AlN film 13. However, the lower electrode film 14 may be disposed above the support body 4 in a state in which the lower electrode film 14 is in contact with the upper surface of the support body 4.

[0083] (4) In each of the above-described embodiments, in the manufacture of the piezoelectric device 1, as shown in FIG. 3, the AlN film 13 is patterned into the same planar shape as the lower electrode film 14. However, the AlN film 13 does not necessarily have to be patterned into the same planar shape as the lower electrode film 14. For example, when the lower electrode film 14 is patterned into a predetermined planar shape, the AlN film 13 does not have to be etched away. Even in this case, the lower ScAlN film 15 is continuously formed over both the position above the lower electrode film 14 and the position above the non-electrode region 402 of the insulating film 12. In this case, unlike FIG. 4, the lower ScAlN film 15 is disposed above the non-electrode region 402 via the AlN film 13, and therefore does not contact the upper surface of the non-electrode region 402. However, even in this case, there is a step on the lower side of the lower ScAlN film 15 due to the presence or absence of the lower electrode film 14, and the same effect as in each embodiment can be obtained by performing the same steps as in each embodiment.

[0084] (5) In each of the above-described embodiments, as shown in Fig. 1, slit 303 is formed in floating portion 302, thereby making floating portion 302 a cantilever. However, slit 303 does not have to be formed in floating portion 302. In other words, floating portion 302 does not have to be a cantilever.

[0085] (6) In each of the above-described embodiments, the piezoelectric device 1 is used as a microphone. However, the piezoelectric device 1 may be used as a sensor other than a microphone.

[0086] (7) The present invention is not limited to the above-described embodiment, and can be appropriately modified within the scope of the claims, and includes various modified examples and modifications within the equivalent scope. The above-described embodiments are not unrelated to each other, and can be appropriately combined, except when the combination is clearly impossible. In the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except when they are specifically stated to be essential or when they are clearly considered to be essential in principle. In the above-described embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiments are mentioned, they are not limited to the specific numbers, except when they are specifically stated to be essential or when they are clearly limited to a specific number in principle. In the above-described embodiments, when the materials, shapes, positional relationships, etc. of the components are mentioned, they are not limited to the materials, shapes, positional relationships, etc., except when they are specifically stated to be essential or when they are clearly limited to a specific material, shape, positional relationship, etc. in principle. [Explanation of symbols]

[0087] 2 Support 4. Support body 5 Space part 14 Lower electrode film 15 Lower layer ScAlN film 151 Predetermined area 16 Intermediate electrode membrane 17 Upper layer ScAlN film 18 Upper electrode film

Claims

1. 1. A piezoelectric device, comprising: A support (2) having a support body portion (4) and a space portion (5); a lower electrode film (14) disposed above at least the support body; a lower layer ScAlN film (15) that is disposed above the support body and the space, and is continuous over both a position above the lower electrode film and a position above a non-electrode region (402) of the support body where the lower electrode film is not disposed, and is made of ScAlN; an intermediate electrode film (16) disposed above at least a portion of the lower electrode film and laminated on the lower ScAlN film; an upper layer ScAlN film (17) made of ScAlN, which is disposed above the support body and the space, and is laminated on the intermediate electrode film and on a region of the lower layer ScAlN film where the intermediate electrode film is not disposed; an upper electrode film (18) disposed above at least a portion of the intermediate electrode film and laminated on the upper layer ScAlN film; a portion (302) of the laminate (3) including the lower ScAlN film and the upper ScAlN film located above the space portion is a membrane structure; the lower layer ScAlN film has a predetermined region (151, 151A, 151B, 151C, 151D) located above the non-electrode region of the support body and adjacent to the lower electrode film in a direction along the upper surface of the support body, The concentration of the predetermined element in the predetermined region is higher than that of a membrane region (152) constituting the membrane structure in the lower ScAlN film, A piezoelectric device, wherein the predetermined element is Al, Sc, N, or an element of the same group as these, or a rare gas, or oxygen.

2. The piezoelectric device of claim 1, wherein a concentration of the specified element is lower in a lower portion (151C2) of the specified region that is located lower than the upper portion (151C1) of the specified region that is located on the upper side of the specified region (151C).

3. The piezoelectric device according to claim 2 , wherein the lower portion is a portion having a thickness (T4) of 100 nm from the lower end of the lower ScAlN film.

4. The piezoelectric device according to claim 1 , wherein at least a portion of the predetermined region (151D) is amorphous.

5. A method for manufacturing a piezoelectric device, comprising the steps of: forming a lower electrode film (14) on a support (2); forming a lower layer ScAlN film (15) made of ScAlN, the lower layer ScAlN film (15) being continuous over both a position above the lower electrode film and a position above a non-electrode region (402) of the support where the lower electrode film is not disposed; forming an intermediate electrode film (16) on the lower ScAlN film; Before or after the formation of the intermediate electrode film, ion implantation is performed on a predetermined region (151, 151A, 151B, 151C, 151D) of the lower ScAlN film located above the non-electrode region and adjacent to the lower electrode film in a direction along the upper surface of the support; forming an upper layer ScAlN film (17) made of ScAlN on the intermediate electrode film and on a region of the lower layer ScAlN film where the intermediate electrode film is not disposed; forming an upper electrode film (18) on the upper ScAlN film.

6. 6. The method for manufacturing a piezoelectric device according to claim 5, wherein the ion implantation uses, as an ion species, Al, Sc, N, or elements of the same group as these, or a rare gas, or oxygen.

7. 7. The method for manufacturing a piezoelectric device according to claim 5, wherein the ion implantation is performed once or a plurality of times during the formation of the lower ScAlN film.

8. 8. A method for manufacturing a piezoelectric device according to claim 5, wherein, in the ion implantation, an amount of ions implanted into a lower portion (151C2) located lower than the upper portion (151C1) of the specified region (151C) is made smaller than an amount of ions implanted into an upper portion (151C1) located on the upper side of the specified region (151C).

9. The method for manufacturing a piezoelectric device according to claim 8 , wherein the lower portion is a portion having a thickness (T4) of 100 nm from a lower end of the lower ScAlN film.

10. 10. The method for manufacturing a piezoelectric device according to claim 5, wherein the ion implantation causes at least a part of the predetermined region (151D) to become amorphous by the ion implantation.

11. A method for manufacturing a piezoelectric device, comprising the steps of: forming a lower electrode film (14) on a support (2); forming a lower layer ScAlN film (15) made of ScAlN, the lower layer ScAlN film (15) being continuous over both a position above the lower electrode film and a position above a non-electrode region (402) of the support where the lower electrode film is not disposed; Irradiating a laser beam (La) to a predetermined region (151E) of the lower layer ScAlN film located above the non-electrode region and adjacent to the lower electrode film in a direction along the upper surface of the support, thereby heating the region; forming an intermediate electrode film (16) on the lower ScAlN film after the irradiation of the laser light; forming an upper layer ScAlN film (17) made of ScAlN on the intermediate electrode film and on a region of the lower layer ScAlN film where the intermediate electrode film is not disposed; forming an upper electrode film (18) on the upper ScAlN film.

12. The method for manufacturing a piezoelectric device according to claim 11, wherein the heating temperature in the heating by irradiating the laser light is 600° C. or more and 1000° C. or less.

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