US20170163241A1 - Acoustic wave device and method for producing same - Google Patents
Acoustic wave device and method for producing same Download PDFInfo
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- US20170163241A1 US20170163241A1 US15/431,610 US201715431610A US2017163241A1 US 20170163241 A1 US20170163241 A1 US 20170163241A1 US 201715431610 A US201715431610 A US 201715431610A US 2017163241 A1 US2017163241 A1 US 2017163241A1
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Images
Classifications
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- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/25—Constructional features of resonators using surface acoustic waves
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
- B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
- B05D3/12—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by mechanical means
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
- H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
- H03H3/08—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of resonators or networks using surface acoustic waves
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/02535—Details of surface acoustic wave devices
- H03H9/02614—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical waves
- H03H9/02629—Treatment of substrates, e.g. curved, spherical, cylindrical substrates ensuring closed round-about circuits for the acoustical waves of the edges
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/02—Details
- H03H9/05—Holders; Supports
- H03H9/10—Mounting in enclosures
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
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- H03H9/02—Details
- H03H9/05—Holders; Supports
- H03H9/10—Mounting in enclosures
- H03H9/1064—Mounting in enclosures for surface acoustic wave [SAW] devices
- H03H9/1071—Mounting in enclosures for surface acoustic wave [SAW] devices the enclosure being defined by a frame built on a substrate and a cap, the frame having no mechanical contact with the SAW device
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- H—ELECTRICITY
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- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/15—Constructional features of resonators consisting of piezoelectric or electrostrictive material
- H03H9/17—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator
- H03H9/171—Constructional features of resonators consisting of piezoelectric or electrostrictive material having a single resonator implemented with thin-film techniques, i.e. of the film bulk acoustic resonator [FBAR] type
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T83/00—Cutting
- Y10T83/04—Processes
- Y10T83/0524—Plural cutting steps
Definitions
- the present invention relates to an acoustic wave device such as a surface acoustic wave (SAW) device or a film bulk acoustic resonator (FBAR) or the like and a method of producing the same.
- SAW surface acoustic wave
- FBAR film bulk acoustic resonator
- Patent literature 1 discloses an acoustic wave device improved in shock resistance by covering side surfaces or a back surface (main surface on the side opposite to the main surface having an acoustic wave element provided thereon) of the substrate by a resin.
- Patent Literature 1 refers to the shock resistance, but does not particularly take note of impact from a side direction of the substrate.
- the acoustic wave device of Patent Literature 1 is not a particularly preferred aspect against impact from the side direction of a substrate.
- an acoustic wave device capable of improving the shock resistance from a side direction of a substrate and a method of production of the same be provided.
- Patent literature 1 Japanese Patent Publication (A) No. 2008-5464
- An acoustic wave device has a substrate and an acoustic wave element on one main surface of the substrate. On the side surface of the substrate, a protruding portion is provided which protrudes out from the side surfaces at a side of the other main surface compared with a side of the one main surface.
- a method of production of an acoustic wave device has a first cutting step of cutting a wafer, on one main surface of which a plurality of acoustic wave elements are provided, at the part of that one main surface side by a first blade so as to form groove portions which partition a plurality of acoustic wave devices and a second cutting step of cutting the wafer at the part of the other main surface side along the groove portions by a second blade having a thinner blade thickness than the first blade so as to separate the wafer.
- the protruding portion is more easily impacted.
- maintaining the performance of the acoustic wave device rather than maintaining the shape of the part at the other main surface side, maintaining the shape of the part at the one main surface side on which the acoustic wave element is provided is more important. Accordingly, this means that the acoustic wave device is improved in shock resistance from the side direction of the substrate as a whole. Therefore, the maintenance of shape of the acoustic wave element and maintenance of adhesion between the cover and the substrate are improved.
- FIG. 1 is a perspective view showing an appearance of a SAW device according to a first embodiment of the present invention.
- FIG. 2 is a perspective view schematically showing the SAW device of FIG. 1 partially cut away.
- FIG. 3 is a conceptual cross-sectional view along the line III-III in FIG. 1 .
- FIGS. 4A, 4B, 4C and 4D are cross-sectional views for explaining a method of production of the SAW device in FIG. 1 .
- FIGS. 5A , 5B and 5D are cross-sectional views showing a continuation of FIG. 4D .
- FIGS. 6A, 6B, 6C and 6D are cross-sectional views showing a continuation of FIG. 5C .
- FIGS. 7A, 7B and 7C are cross-sectional views showing protruding portions according to first to third modifications.
- FIG. 1 is a perspective view of the appearance of a SAW device 1 according to an embodiment of the present invention.
- the SAW device 1 is constituted by a so-called wafer level package (WLP) type SAW device.
- the SAW device 1 is formed in a general block shape as a whole. At one surface of the block, a plurality of terminals 3 are exposed. The number and arrangement positions of the plurality of terminals 3 are suitably set in accordance with the configuration of the electronic circuit inside the SAW device 1 .
- the present embodiment illustrates a case where six terminals 3 are arranged along an outer edge of one surface.
- the SAW device 1 receives as input a signal through any of the plurality of terminals 3 .
- the input signal is filtered by the SAW device 1 .
- the SAW device 1 outputs the filtered signal through any of the plurality of terminals 3 .
- the SAW device 1 is for example mounted on the mounting surface of a not shown circuit board or the like with the surface at which the plurality of terminals 3 are exposed made to face that mounting surface and is sealed by a resin in that state. Due to this, it is mounted in a state with the terminals 3 connected to the terminals on the mounting surface.
- FIG. 2 is a perspective view showing the SAW device 1 partially cut away. Further, FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 1 .
- the SAW device 1 has a substrate 5 and SAW elements 7 provided on the substrate 5 . Further, for the purpose of protection etc. of the SAW elements 7 , the SAW device 1 has a cover 9 covering the SAW elements 7 , a resin film 11 covering side surfaces of the substrate 5 , a back surface electrode 13 provided on the substrate 5 at the side opposite to the SAW element 7 side, and a resin layer 15 laminated on the back surface electrode 13 .
- the substrate 5 is constituted by a piezoelectric substrate.
- the substrate 5 is a single crystal substrate having a piezoelectric property such as a lithium tantalite single crystal, lithium niobate single crystal, or the like.
- the substrate 5 is generally formed in a thin block shape and has a first main surface 5 a, a second main surface 5 b ( FIG. 3 ) on the back surface side of the same, and side surfaces 5 c facing the sides (outer circumference side) of the first main surface 5 a and second main surface 5 b.
- a protruding portion 5 d protruding outward from the side surfaces 5 c is formed.
- the protruding portion 5 d is provided along the outer circumference of the second main surface 5 b over the entire outer circumference. In other words, it is also possible to grasp that the protruding portion 5 d is formed by the side surfaces 5 c being expanded at the parts at the second main surface 5 b sides and possible to grasp that it is formed by parts which remain without being cut away when cutting away the piezoelectric substrate 3 at the first main surface 5 a side over the entire outer circumference.
- the cross-sectional shape (cross-sectional shape shown in FIG. 3 ) of the protruding portion 5 d is generally rectangular.
- the protruding portion 5 d is provided in a “second region” when equally dividing the side surfaces 5 c in the vertical direction into two into a first region (region on first main surface 5 a side) and a second region (region on second main surface 5 b side).
- the length of one side of the substrate 5 is for example 0.5 mm to 2 mm.
- the thickness of the substrate 5 is for example 0.2 mm to 0.5 mm.
- the amount of protrusion of the protruding portion 5 d is for example 5 to 10 ⁇ m.
- the thickness of the protruding portion 5 d is for example 25 to 50 ⁇ m.
- Each SAW element 7 is an element for filtering a signal which is input to the SAW device 1 .
- the SAW element 7 is provided on the first main surface 5 a.
- the SAW element 7 has a pair of comb-shaped electrodes (IDT electrodes) 17 .
- Each comb-shaped electrode 17 has a bus bar 17 a ( FIG. 2 ) extending in the propagation direction (X-direction) of the SAW in the substrate 5 and a plurality of electrode fingers 17 b extending from the bus bar 17 a in a direction (Y-direction) perpendicular to the above propagation direction.
- the comb-shaped electrodes 17 are provided so that their electrode fingers 17 b mesh with each other.
- FIG. 2 and FIG. 3 are schematic views, so show one pair of comb-shaped electrodes 17 each having several electrode fingers 17 b. In actuality, two or more pairs of comb-shaped electrodes each having a number of electrode fingers larger than this may be provided.
- a ladder type SAW filter, double mode SAW resonator filter, or the like may be constituted by a plurality of SAW elements 7 connected in serial connection, parallel connection, or other method.
- the SAW elements 7 are formed by for example Al alloy such as Al-Cu alloy or the like.
- the cover 9 has a frame 19 surrounding the SAW elements 7 in a plan view of the first main surface 5 a and has a lid 21 closing the opening of the frame 19 . Further, the spaces surrounded by the first main surface 5 a (strictly speaking, a protective film 29 which is explained later), frame 19 , and lid 21 form vibration spaces S for facilitating the propagation of the SAW. Note that, the vibration spaces S may be provided in suitable numbers and shapes. The present application illustrates a case where two vibration spaces S are provided.
- the frame 19 is comprised of a layer having a generally constant thickness in which one or more openings which become vibration spaces S are formed. In the present embodiment, two vibration spaces S are provided.
- the thickness of the frame 19 (height of the vibration spaces S) is for example several ⁇ m to 30 ⁇ m.
- the lid 21 is constituted by a layer having a generally constant thickness which is laminated on the frame 19 . The thickness of the lid 21 is for example several pm to 30 ⁇ m.
- the planar shape of the cover 9 is similar to the planar shape of the substrate 5 and is rectangular in the present embodiment.
- the cover 9 has for example a generally equivalent area with the first main surface 5 a and covers generally the entire surface of the first main surface 5 a.
- the cover 9 is a bit smaller than the first main surface 5 a, so steps is formed between the side surfaces 5 c and the side surfaces 9 c of the cover 9 .
- the steps is formed over the entire circumference of the first main surface 5 a.
- the size of the steps is for example 5 to 20 ⁇ m.
- the frame 19 and lid 21 are formed by for example a photosensitive resin.
- the photosensitive resin is for example a urethane acrylate-based, polyester acrylate-based, or epoxy acrylate-based resin which is cured by radical polymerization of acryl groups, methacryl groups, or the like.
- the frame 19 and lid 21 may be formed by the same material or may be formed by materials different from each other. In the present example, for convenience of explanation, the borderline between the frame 19 and the lid 21 is clearly indicated. However, in an actual product, the frame 19 and lid 21 may be formed by the same material and formed integrally as well.
- the resin film 11 covers the side surfaces 5 c at the parts at the first main surface 5 a side other than the protruding portion 5 d and the side surfaces 9 c of the cover 9 .
- the resin film 11 is provided so as to bury the steps caused by the protruding portion 5 d and the step between the substrate 5 and the cover 9 so that the outer shape of the SAW device 1 constituted by the substrate 5 , cover 9 , and resin film 11 becomes a block shape. That is, the resin film 11 covers the entire surfaces of the side surfaces 5 c at the parts at the first main surface 5 a side other than the protruding portion 5 d and the entire surfaces of the side surfaces 9 c.
- outer circumferential surface 11 e of the resin film 11 is flush with the top face 5 e of the protruding portion 5 d, and end surface 11 a of the resin film 11 on the first main surface 5 a side is flush with the top face 9 a of the cover 9 .
- the resin film 11 is formed by for example a novolac-based resin, epoxy resin, Biphenol resin, or polyimide resin.
- the resin film 11 has a lower Young's modulus than the substrate 5 . That is, the resin film 11 is softer than the substrate 5 and easily absorbs shock.
- the back surface electrode 13 covers the entire surface of the second main surface 5 b.
- the thickness of the back surface electrode 13 is for example 1 ⁇ m to several ⁇ m.
- the back surface electrode 13 is formed by for example an Al alloy such as an Al-Cu alloy or the like. The charges formed in the substrate 5 due to temperature change etc. flow to the back surface electrode 13 , whereby pyroelectric breakdown of the SAW elements 7 is suppressed.
- the resin layer 15 covers the entire surface of the second main surface 5 b (back surface electrode 13 ).
- the thickness of the resin layer 15 is for example 25 ⁇ m to 50 ⁇ m.
- the resin layer 15 is formed by for example a thermosetting resin such as an epoxy resin or the like.
- the resin layer 15 has a lower Young's modulus than the substrate 5 in the same way as the resin film 11 .
- the terminals 3 are formed standing at the first main surface 5 a and are exposed at the upper surface 9 a of the cover 9 through holes 9 h formed in the cover 9 .
- the holes 9 h penetrate through the frame 19 and lid 21 in directions facing the first main surface 5 a at the outsides of the vibration spaces S.
- the first main surface 5 a is provided with lines 23 ( FIG. 2 ) connected to the SAW elements 7 and a plurality of pads 25 connected to the lines 23 .
- the terminals 3 are connected to the SAW elements 7 by being provided on the pads 25 .
- a conductive layer 27 and a protective film 29 covering the conductive layer 27 are provided on the first main surface 5 a.
- the conductive layer 27 forms the SAW elements 7 , at least a part of the lines 23 ( FIG. 2 ), and at least a part of the pads 25 .
- the conductive layer 27 is formed by for example an Al alloy such as an Al-Cu alloy or the like. Its thickness is for example 100 to 300 nm.
- the protective film 29 contributes to prevention of oxidation etc. of the conductive layer 27 .
- the protective film 29 is formed by for example a material which has an insulating property and has a mass light enough so as not to influence the propagation of the SAW.
- the protective film 29 is formed by silicon oxide (SiO2 etc.), silicon nitride, silicon or the like.
- the thickness of the protective film 29 is for example about 1/10 (10 nm to 30 mm) of the thickness of the conductive layer 27 or equal to or more than the thickness of the conductive layer 27 (100 nm to 300 nm).
- the protective film 29 is for example provided over generally the entire first main surface 5 a, while the cover 9 is laminated over the protective film 29 . Further, also the part of the resin film 11 which is on the first main surface 5 a is laminated over the protective film 29 . On the other hand, at the positions of arrangement of the terminals 3 , the protective film 29 is removed so that the pads 25 are exposed from the protective film 29 .
- the cover 9 is not directly provided on the first main surface 5 a, but is provided on the protective film 29 or the like.
- the cover 9 is not directly provided on the first main surface 5 a, but is provided on the protective film 29 or the like.
- predetermined members, layers, etc. are indirectly provided on the main surface of the substrate 5 in this way and are not directly provided on the main surface of the substrate 5 , it is sometimes expressed so that these predetermined members, layers, etc. are provided on the main surface of the substrate 5 . This is true for the word “laminate” as well.
- an insulation film which is laminated on the conductive layer 27 or protective film 29 , another conductive layer which is laminated on the conductive layer 27 with the insulation film interposed therebetween and forms a part of the lines 23 , a connection strengthening layer which forms upper layer portions of the pads 25 and strengthens the connection between the pads 25 and the terminals 3 , and so on may be provided as well.
- FIG. 4A to FIG. 6D are cross-sectional views for explaining the method of production of the SAW device 1 . The steps are advanced in order from FIG. 4A to FIG. 6D .
- a mother board (wafer 31 ) which is later divided to form the substrates 5 is formed with a thin film, processed by photolithography, etc., then is diced to form a large number of SAW devices in parallel.
- FIG. 4A to FIG. 5C only parts corresponding to one SAW device 1 are shown.
- FIG. 6A to FIG. 6D only parts corresponding to three SAW devices 1 are shown.
- the conductive layer, insulation layer, etc. change in shapes along with the progress in the process. However, common notations are used before and after the changes. In the same way, notations of the first main surface 5 a and second main surface 5 b of the substrate 5 are assigned to the first main surface and second main surface of the wafer 31 .
- a conductive layer 27 is formed.
- the thin film forming method such as the sputtering method, vapor deposition method, CVD (chemical vapor deposition) method, or the like is used to form a metal layer which becomes the conductive layer 27 on the first main surface 5 a.
- the metal layer is patterned by photolithography etc. using a reduced protrusion exposure machine (stepper) and RIE (reactive ion etching) device. Therefore, a conductive layer 27 including the SAW elements 7 , at least a part of the lines 23 , and at least a part of the pads 25 is formed.
- the protective film 29 is formed. Specifically, first, a thin film which becomes the protective film 29 is formed by the thin film forming method such as the CVD method or vapor deposition method or the like. Next, parts of the thin film are removed by the photolithography method so that parts of the conductive layer 27 which constitute the pads 25 are exposed. Accordingly, the protective film 29 is formed.
- the thin film forming method such as the CVD method or vapor deposition method or the like.
- a thin film which becomes the frame 19 is formed.
- the thin film is formed by for example adhesion of a film formed by a photosensitive resin or a thin film forming method the same as that for the protective film 29 etc.
- the photolithography method is used to remove parts of the thin film and form openings which becomes the vibration spaces S and lower side portions of the holes 9 h. Further, groove portions are formed along the dicing lines, and side surfaces of the frame 19 are formed as well. That is, the frame 19 is formed from the thin film.
- the photolithography may be either of the positive type or the negative type.
- the lid 21 is formed by the same method as the method of formation of the frame 19 . Specifically, first, a thin film which becomes the lid 21 is formed. The thin film is formed by for example adhesion of a film formed by a photosensitive resin. By laminating the thin film on the frame 19 , the openings of the frame 19 are closed, and the vibration spaces S are constituted.
- the photolithography method parts of the thin film are removed, and upper side portions of the holes 9 h are formed. Further, groove portions are formed along the dicing lines, and side surfaces of the frame 19 are formed. That is, the lid 21 is formed from the thin film.
- the photolithography may be either of the positive type or negative type.
- terminals 3 are formed. Specifically, first, a base layer 33 is formed over the upper face 9 a of the cover 9 and the inside of the holes 9 h.
- the base layer 33 is a metal layer and is formed by for example the sputtering method.
- a resist layer 37 is formed on the base layer 33 .
- the resist layer 37 is for example formed by having a thin film formed on the substrate by a spin coating method or other technique and having that thin film patterned by the photolithography method. By removal of parts of the thin film by patterning, the base layer 33 is exposed at the holes 9 h and their peripheral parts.
- the electroplating method is used to cause a metal to deposit on the exposed parts of the base layer 33 . Accordingly, solid parts 35 are formed.
- the terminals 3 are formed. That is, the surface parts of the terminals 3 are constituted by the base layer 33 , and internal parts (majority) of the terminals 3 are constituted by the solid parts 35 . Note that, in FIG. 3 , illustration of the base layer 33 is omitted.
- the back surface electrode 13 and resin layer 15 are sequentially formed ( FIG. 5C ).
- the back surface electrode 13 is formed by the thin film forming method such as the sputtering method, vapor deposition method, CVD method, or the like.
- the resin layer 15 is formed by for example adhering a resin sheet to the back surface electrode 13 , and then thermosetting it. Note that, the resin layer 15 may be formed by a potting method or printing method as well.
- the resin layer 15 of the wafer state SAW devices 1 and a dicing tape 39 are bonded.
- a first blade 41 is used to the portions of the wafer 31 on the first main surface 5 a side along the dicing lines. Accordingly, groove portions 31 a partitioning a plurality of SAW devices 1 are formed.
- resin constituting the resin film 11 is filled in the groove portions 31 a.
- the resin is filled by using for example a dispenser 43 . Further, the filled resin is cured by heating.
- a second blade 45 having a thinner blade thickness than the first blade 41 is used to cut the wafer-state SAW devices 1 along the groove portions 31 a from the first main surface 5 a side. Specifically, the resin filled in the groove portions 31 a, parts of the wafer 31 at the second main surface 5 b side, the back surface electrode 13 , and the resin layer 15 are cut at schematically the center of the groove portions 31 a.
- the first blade 41 is for example a fixed abrasive type blade and has a plurality of fixed abrasive grains 41 a and a connecting material 41 b holding the plurality of fixed abrasive grains 41 a.
- the second blade 45 has a plurality of fixed abrasive grains 45 a and a connecting material 45 b holding the plurality of fixed abrasive grains 45 a.
- the material of the abrasive grains, particle size, the density of the abrasive grains, the material of the connecting material, and blade thickness may be suitably selected. Part of the conditions other than the blade thickness may be shared between the first blade 41 and the second blade 45 . For example, between the first blade 41 and the second blade 45 , the material of the abrasive grains, particle size, and the density of abrasive grains are shared, but the type of the connecting material is different.
- the connecting material 41 b one suitable for cutting a piezoelectric substrate (substrate 5 ) is selected, while as the connecting material 45 b , one suitable for cutting a resin (at least one of the resin film 11 and resin layer 15 ) is selected.
- each SAW device 1 has a substrate 5 and SAW elements 7 on the first main surface 5 a of the substrate 5 .
- a protruding portion 5 d is provided at the second main surface 5 b side compared with the first main surface 5 a.
- the SAW device 1 when shock is applied to a side surface 5 c, the protruding portion 5 d is more easily impacted than the part of the side surface 5 c at the first main surface 5 a side.
- maintaining the performance of the SAW device 1 rather than maintaining the shape of the part at the second main surface 5 b side, maintaining the shape of the part at the first main surface 5 a side is more important. Accordingly, this means that the SAW device 1 is improved in shock resistance from the side direction of the substrate 5 as a whole.
- Patent Literature 1 does not disclose the idea of protecting the first main surface 5 a side against the impact from the side surface with priority over the second main surface 5 b side.
- the protruding portion 5 d is provided along the outer circumference of the second main surface 5 b. Accordingly, it is possible to strengthen the protection of the first main surface 5 a side against impact from various directions parallel to the first main surface 5 a. Further, as explained with reference to FIG. 6B and FIG. 6D , the protruding portion 5 d can be formed by a simple and convenient method of changing the cutting width at the time of dicing, for example, the protruding portion 5 d can be formed by using the first blade 41 and second blade 45 having different blade thicknesses.
- the SAW device 1 has the resin layer 11 which covers the side surfaces 5 c at the parts of the first main surface 5 a side other than the protruding portion 5 d, abuts against the protruding portion 5 d from the first main surface 5 a side, and is softer than the substrate 5 . Accordingly, due to the resin film 11 , shock with respect to a side surface 5 c can be absorbed, and protection of the parts of the SAW device 1 at the first main surface 5 a side can be strengthened.
- a “resin film 11 which is softer than the substrate 5 ” means “softer” when compared in Young's modulus. That is, the resin film 11 has a smaller Young's modulus than the substrate 5 .
- the protruding portion 5 d functions as a stopper which limits movement of the resin film 11 to the second main surface 5 b side, whereby peeling of the resin film 11 from the side surfaces 5 c is suppressed.
- the resin film 11 may also be formed so that its side surfaces are located at the inner side compared with the protruding portion 5 d.
- the protruding portion 5 d may be formed so that it protrudes outward compared with the side surfaces of the resin film 11 . Due to this, when an object having a surface parallel to a side surface strikes a SAW device 1 from the side direction of the substrate 5 , that object strikes the protruding portion 5 d, so propagation of a large impact to the first main surface 5 a of the SAW device 1 can be suppressed.
- the SAW device 1 has the cover 9 which is provided on the first main surface 5 a and seals the SAW elements 7 .
- the side surfaces 9 c of the cover 9 form steps by being positioned at the inner sides from the side surfaces 5 c of the substrate 5 .
- the resin film 11 is provided so as to straddle the side surfaces 9 c of the cover 9 from the side surfaces 5 c of the substrate 5 and abuts against the steps from the first main surface 5 a side. Accordingly, by covering of mating parts of the cover 9 and substrate 5 (strictly speaking, protective film 29 ) by the resin film 11 , invasion of moisture from the mating parts and peeling of the cover 9 from the substrate 5 are suppressed. Further, the steps formed by the cover 9 and substrate 5 function as stoppers which limit movement of the resin film 11 to the second main surface 5 b side, so peeling of the resin film 11 from the side surface 9 c and side surface 5 c is suppressed.
- the method of production of the SAW device 1 has a first cutting step ( FIG. 6B ) of cutting the wafer 31 , on the first main surface 5 a of which a plurality of SAW elements 7 are provided, at the parts of the first main surface 5 a sides by the first blade 41 so as to form groove portions 31 a for partitioning the plurality of SAW devices 1 .
- this method of production has a second cutting step ( FIG. 6D ) of cutting the wafer 31 at parts of the second main surface 5 b sides along the groove portions 31 a by the second blade 45 having a thinner blade thickness than the first blade 41 so as to separate the wafer 31 .
- the protruding portions 5 d can be simply formed. Further, blades which are different from each other are used in the two steps, therefore blades suitable for the steps can be used. For example, in the first cutting step ( FIG. 6B ), cutting is carried out at a high speed by cutting by the first blade 41 having the large particle size, while in the second cutting step ( FIG. 6D ), chipping, which easily occurs when a blade passes through a wafer, can be suppressed by cutting by the second blade 45 having a small particle size.
- the method of production of the SAW device 1 further has a step ( FIG. 6C ) of filling resin in the groove portions 31 a after the first cutting step ( FIG. 6B ) and before the second cutting step ( FIG. 6D ). Accordingly, the above-mentioned resin film 11 which covers the side surfaces 5 c at the first main surface 5 a side other than the protruding portion 5 d and adheres to the protruding portion 5 d can be simply constituted.
- the method of production of the SAW device 1 further has a step ( FIG. 5C ) of forming the resin layer 15 on the second main surface 5 b of the wafer 31 before the first cutting step ( FIG. 6B ).
- the resin layer 15 is not cut in the first cutting step ( FIG. 6B ), but the resin layer 15 is cut in the second cutting step ( FIG. 6D ). Accordingly, by selecting as the first blade 45 one suitable for cutting the piezoelectric substrate and as the second blade 45 selecting one suitable for cutting the resin layer 15 , chipping and cracks in the second main surface 5 b can be suppressed.
- FIG. 7A to FIG. 7C are cross-sectional views showing first to third modifications of the protruding portion 5 d.
- the protruding portions 5 d of the first to third modifications are formed tapered so as to spread further outward toward the second main surface 5 b side.
- the protruding portions 5 d of the first to third modifications protrude out further the more toward the second main surface 5 b sides (the closer in position to the second main surfaces 5 b ).
- the protruding portion 5 d is formed so that its cross-sectional shape becomes a generally right triangle.
- the protruding portion 5 d is formed so that its cross-sectional shape becomes generally trapezoidal.
- the protruding portion 5 d is formed so that the cross-sectional shape of the part at the first main surface 5 a side is generally rectangular (square) and the cross-sectional shape of the part at the second main surface 5 b side is generally trapezoidal.
- the angle of inclination of the tapered surface ( 5 e ) of the protruding portion 5 d relative to the side surface 5 c (defined as 0° when the tapered surface is parallel to the side surface 5 c ) is for example 5° to 40°.
- the protruding portion 5 d may be provided along the outer circumference of the second main surface 5 b, the resin film 11 which abuts against the protruding portion 5 d from the first main surface 5 a side may be provided, and so on in the same way as the above embodiment.
- the protruding portion 5 d in the first modification can relieve stress concentration at the base of the protruding portion 5 d at the first main surface 5 a side compared with the protruding portion 5 d in the above embodiment, while can cause the positions where impact occurs to concentrate at the second main surface 5 b side. Further, compared with the protruding portion 5 d in the above embodiment, the protruding portions 5 d in the second and third modifications can cause the positions where impact occurs to concentrate at the second main surface 5 b side.
- the protruding portions 5 d in the first to third modifications can be formed by for example forming the entire second blade 45 or its outer circumferential edge to be tapered.
- the finite element method was used to calculate the stress distribution in the substrate 5 in time sequence.
- the protruding portion 5 d impacts the XZ surface whereby stress is generated at the protruding portion 5 d. This stress is propagated to the entire substrate 5 along with the elapse of time. This situation was reproduced and the stress of each part of the substrate 5 at each point of time was examined.
- the position of generation and point of time of generation in the first main surface 5 a of the maximum stress which is generated in the first main surface 5 a differ according to the simulation conditions.
- the maximum value of stress generated in the first main surface 5 a was smaller in the case where the protruding portion 5 d was tapered so as to further protrude outward toward the second main surface 5 b side than the case where the protruding portion 5 d was rectangular.
- the acoustic wave device is not limited to a SAW device.
- the acoustic wave device may be a film bulk acoustic resonator.
- the acoustic wave device may be a boundary acoustic wave device utilizing a boundary acoustic wave.
- the resin film ( 11 ), back surface electrode ( 13 ), resin layer ( 15 ), and protective film ( 29 ) may be omitted. Conversely, other suitable layers etc. may be formed. Further, in the case of the boundary acoustic wave device, an acoustic wave device can be prepared without provision of vibration spaces S.
- the shape of the protruding portion 5 d is not limited to the above explained ones.
- the protruding portion 5 d may be formed so as to gradually become broader from the first main surface 3 a of the piezoelectric substrate 3 toward the second main surface 3 b.
- the protruding portion 5 d may be provided so that the shape of the piezoelectric substrate 3 becomes generally trapezoidal when viewing it from the side surface.
- the cutting of the wafer is not limited to cutting carried out by using a blade.
- the cutting may be carried out by using a laser.
- a plurality of methods may be combined.
- the first cutting step may be carried out by using a blade and the second cutting step may be carried out by using a laser.
- a side surface ( 5 c ) at the one main surface side ( 5 a ) other than the protruding portion ( 5 d ) and the surface ( 5 e ) of the protruding portion facing the side direction of the substrate can be identified by for example observation of the surfaces by an SEM (scanning electron microscope).
- SEM scanning electron microscope
- the cutting in the second cutting step need not be carried out from one main surface 5 a side (side cut in the first cutting step) or may be carried out from the other main surface 5 b side.
- the resin need not be filled up to the upper surface 9 a of the cover 9 .
- the resin may be filled up to one main surface 5 a of the substrate 5 or a part lower than it, or may be filled up to the upper face of the cover or a part lower than it.
- SAW device acoustic wave device
- 5 . . . substrate 5 a . . . first main surface (one main surface), 5 b . . . second main surface (other main surface), 5 c . . . side surface, 5 d . . . protruding portion, and 7 . . . SAW element (acoustic wave element).
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Abstract
An acoustic wave device comprises a substrate and an acoustic wave element on one main surface of the substrate. Side surfaces of the substrate comprises a protruding portion which protrudes out at a side of an another main surface closer than a side with the one main surface side.
Description
- This application is a divisional of U.S. application Ser. No. 14/629,373 filed on Feb. 23, 2015, which is a divisional of U.S. application Ser. No. 13/498,815 filed on Mar. 28, 2012 and issued as U.S. Pat. No. 5,963,655, which is a 371 National Stage Application of International Application no. PCT/JP2010/071154 filed on Nov. 26, 2010 which claims the benefit of Japanese Application no. 2009-269576 filed on Nov. 27, 2009. The contents of each of the above applications are incorporated by reference herein in their entirety.
- The present invention relates to an acoustic wave device such as a surface acoustic wave (SAW) device or a film bulk acoustic resonator (FBAR) or the like and a method of producing the same.
- An acoustic wave device having a substrate and an acoustic wave element provided on a main surface of the substrate is known.
Patent literature 1 discloses an acoustic wave device improved in shock resistance by covering side surfaces or a back surface (main surface on the side opposite to the main surface having an acoustic wave element provided thereon) of the substrate by a resin. - An acoustic wave device is sometimes impacted from a side direction of the substrate at the time of transport during the period from manufacture to mounting etc. Note that,
Patent Literature 1 refers to the shock resistance, but does not particularly take note of impact from a side direction of the substrate. As a result, the acoustic wave device ofPatent Literature 1 is not a particularly preferred aspect against impact from the side direction of a substrate. - Accordingly, it is preferable that an acoustic wave device capable of improving the shock resistance from a side direction of a substrate and a method of production of the same be provided.
- Patent literature 1: Japanese Patent Publication (A) No. 2008-5464
- An acoustic wave device according to an embodiment of the present invention has a substrate and an acoustic wave element on one main surface of the substrate. On the side surface of the substrate, a protruding portion is provided which protrudes out from the side surfaces at a side of the other main surface compared with a side of the one main surface.
- A method of production of an acoustic wave device according to an embodiment of the present invention has a first cutting step of cutting a wafer, on one main surface of which a plurality of acoustic wave elements are provided, at the part of that one main surface side by a first blade so as to form groove portions which partition a plurality of acoustic wave devices and a second cutting step of cutting the wafer at the part of the other main surface side along the groove portions by a second blade having a thinner blade thickness than the first blade so as to separate the wafer.
- According to the above constitution and procedure, when shock is applied to a side surface of an acoustic wave device at the time of transport etc. of the acoustic wave device, the protruding portion is more easily impacted. On the other hand, for maintaining the performance of the acoustic wave device, rather than maintaining the shape of the part at the other main surface side, maintaining the shape of the part at the one main surface side on which the acoustic wave element is provided is more important. Accordingly, this means that the acoustic wave device is improved in shock resistance from the side direction of the substrate as a whole. Therefore, the maintenance of shape of the acoustic wave element and maintenance of adhesion between the cover and the substrate are improved.
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FIG. 1 is a perspective view showing an appearance of a SAW device according to a first embodiment of the present invention. -
FIG. 2 is a perspective view schematically showing the SAW device ofFIG. 1 partially cut away. -
FIG. 3 is a conceptual cross-sectional view along the line III-III inFIG. 1 . -
FIGS. 4A, 4B, 4C and 4D are cross-sectional views for explaining a method of production of the SAW device inFIG. 1 . -
FIGS. 5A , 5B and 5D are cross-sectional views showing a continuation ofFIG. 4D . -
FIGS. 6A, 6B, 6C and 6D are cross-sectional views showing a continuation ofFIG. 5C . -
FIGS. 7A, 7B and 7C are cross-sectional views showing protruding portions according to first to third modifications. - Below, a SAW device according to an embodiment of the present invention is explained with reference to the drawings. Note that, the drawings used in the following explanation are schematic. Dimensions and ratios etc. on the drawings do not always coincide with the actual ones.
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FIG. 1 is a perspective view of the appearance of aSAW device 1 according to an embodiment of the present invention. - The
SAW device 1 is constituted by a so-called wafer level package (WLP) type SAW device. TheSAW device 1 is formed in a general block shape as a whole. At one surface of the block, a plurality ofterminals 3 are exposed. The number and arrangement positions of the plurality ofterminals 3 are suitably set in accordance with the configuration of the electronic circuit inside theSAW device 1. The present embodiment illustrates a case where sixterminals 3 are arranged along an outer edge of one surface. - The
SAW device 1 receives as input a signal through any of the plurality ofterminals 3. The input signal is filtered by theSAW device 1. Then, theSAW device 1 outputs the filtered signal through any of the plurality ofterminals 3. TheSAW device 1 is for example mounted on the mounting surface of a not shown circuit board or the like with the surface at which the plurality ofterminals 3 are exposed made to face that mounting surface and is sealed by a resin in that state. Due to this, it is mounted in a state with theterminals 3 connected to the terminals on the mounting surface. -
FIG. 2 is a perspective view showing theSAW device 1 partially cut away. Further,FIG. 3 is a cross-sectional view taken along the line III-III inFIG. 1 . - The
SAW device 1 has asubstrate 5 andSAW elements 7 provided on thesubstrate 5. Further, for the purpose of protection etc. of theSAW elements 7, theSAW device 1 has acover 9 covering theSAW elements 7, aresin film 11 covering side surfaces of thesubstrate 5, aback surface electrode 13 provided on thesubstrate 5 at the side opposite to theSAW element 7 side, and aresin layer 15 laminated on theback surface electrode 13. - The
substrate 5 is constituted by a piezoelectric substrate. Specifically, for example, thesubstrate 5 is a single crystal substrate having a piezoelectric property such as a lithium tantalite single crystal, lithium niobate single crystal, or the like. Thesubstrate 5 is generally formed in a thin block shape and has a firstmain surface 5 a, a secondmain surface 5 b (FIG. 3 ) on the back surface side of the same, andside surfaces 5 c facing the sides (outer circumference side) of the firstmain surface 5 a and secondmain surface 5 b. On theside surfaces 5 c, a protrudingportion 5 d protruding outward from theside surfaces 5 c is formed. - The protruding
portion 5 d is provided along the outer circumference of the secondmain surface 5 b over the entire outer circumference. In other words, it is also possible to grasp that the protrudingportion 5 d is formed by the side surfaces 5 c being expanded at the parts at the secondmain surface 5 b sides and possible to grasp that it is formed by parts which remain without being cut away when cutting away thepiezoelectric substrate 3 at the firstmain surface 5 a side over the entire outer circumference. The cross-sectional shape (cross-sectional shape shown inFIG. 3 ) of the protrudingportion 5 d is generally rectangular. Further, the protrudingportion 5 d is provided in a “second region” when equally dividing the side surfaces 5 c in the vertical direction into two into a first region (region on firstmain surface 5 a side) and a second region (region on secondmain surface 5 b side). - The length of one side of the
substrate 5 is for example 0.5 mm to 2 mm. The thickness of thesubstrate 5 is for example 0.2 mm to 0.5 mm. The amount of protrusion of the protrudingportion 5 d is for example 5 to 10 μm. The thickness of the protrudingportion 5 d is for example 25 to 50 μm. - Each
SAW element 7 is an element for filtering a signal which is input to theSAW device 1. TheSAW element 7 is provided on the firstmain surface 5 a. TheSAW element 7 has a pair of comb-shaped electrodes (IDT electrodes) 17. Each comb-shapedelectrode 17 has abus bar 17 a (FIG. 2 ) extending in the propagation direction (X-direction) of the SAW in thesubstrate 5 and a plurality ofelectrode fingers 17 b extending from thebus bar 17 a in a direction (Y-direction) perpendicular to the above propagation direction. The comb-shapedelectrodes 17 are provided so that theirelectrode fingers 17 b mesh with each other. - Note that,
FIG. 2 andFIG. 3 are schematic views, so show one pair of comb-shapedelectrodes 17 each havingseveral electrode fingers 17 b. In actuality, two or more pairs of comb-shaped electrodes each having a number of electrode fingers larger than this may be provided. Further, a ladder type SAW filter, double mode SAW resonator filter, or the like may be constituted by a plurality ofSAW elements 7 connected in serial connection, parallel connection, or other method. TheSAW elements 7 are formed by for example Al alloy such as Al-Cu alloy or the like. - The
cover 9 has aframe 19 surrounding theSAW elements 7 in a plan view of the firstmain surface 5 a and has a lid 21 closing the opening of theframe 19. Further, the spaces surrounded by the firstmain surface 5 a (strictly speaking, aprotective film 29 which is explained later),frame 19, and lid 21 form vibration spaces S for facilitating the propagation of the SAW. Note that, the vibration spaces S may be provided in suitable numbers and shapes. The present application illustrates a case where two vibration spaces S are provided. - The
frame 19 is comprised of a layer having a generally constant thickness in which one or more openings which become vibration spaces S are formed. In the present embodiment, two vibration spaces S are provided. The thickness of the frame 19 (height of the vibration spaces S) is for example several μm to 30 μm. The lid 21 is constituted by a layer having a generally constant thickness which is laminated on theframe 19. The thickness of the lid 21 is for example several pm to 30 μm. - The planar shape of the
cover 9 is similar to the planar shape of thesubstrate 5 and is rectangular in the present embodiment. Thecover 9 has for example a generally equivalent area with the firstmain surface 5 a and covers generally the entire surface of the firstmain surface 5 a. However, thecover 9 is a bit smaller than the firstmain surface 5 a, so steps is formed between the side surfaces 5 c and the side surfaces 9 c of thecover 9. The steps is formed over the entire circumference of the firstmain surface 5 a. The size of the steps is for example 5 to 20 μm. - The
frame 19 and lid 21 are formed by for example a photosensitive resin. The photosensitive resin is for example a urethane acrylate-based, polyester acrylate-based, or epoxy acrylate-based resin which is cured by radical polymerization of acryl groups, methacryl groups, or the like. - The
frame 19 and lid 21 may be formed by the same material or may be formed by materials different from each other. In the present example, for convenience of explanation, the borderline between theframe 19 and the lid 21 is clearly indicated. However, in an actual product, theframe 19 and lid 21 may be formed by the same material and formed integrally as well. - The
resin film 11 covers the side surfaces 5 c at the parts at the firstmain surface 5 a side other than the protrudingportion 5 d and the side surfaces 9 c of thecover 9. Theresin film 11 is provided so as to bury the steps caused by the protrudingportion 5 d and the step between thesubstrate 5 and thecover 9 so that the outer shape of theSAW device 1 constituted by thesubstrate 5,cover 9, andresin film 11 becomes a block shape. That is, theresin film 11 covers the entire surfaces of the side surfaces 5 c at the parts at the firstmain surface 5 a side other than the protrudingportion 5 d and the entire surfaces of the side surfaces 9 c. Further, outercircumferential surface 11 e of theresin film 11 is flush with thetop face 5 e of the protrudingportion 5 d, and end surface 11 a of theresin film 11 on the firstmain surface 5 a side is flush with thetop face 9 a of thecover 9. - The
resin film 11 is formed by for example a novolac-based resin, epoxy resin, Biphenol resin, or polyimide resin. Theresin film 11 has a lower Young's modulus than thesubstrate 5. That is, theresin film 11 is softer than thesubstrate 5 and easily absorbs shock. - The
back surface electrode 13 covers the entire surface of the secondmain surface 5 b. The thickness of theback surface electrode 13 is for example 1 μm to several μm. Theback surface electrode 13 is formed by for example an Al alloy such as an Al-Cu alloy or the like. The charges formed in thesubstrate 5 due to temperature change etc. flow to theback surface electrode 13, whereby pyroelectric breakdown of theSAW elements 7 is suppressed. - The
resin layer 15 covers the entire surface of the secondmain surface 5 b (back surface electrode 13). The thickness of theresin layer 15 is for example 25 μm to 50 μm. Theresin layer 15 is formed by for example a thermosetting resin such as an epoxy resin or the like. Theresin layer 15 has a lower Young's modulus than thesubstrate 5 in the same way as theresin film 11. - The
terminals 3 are formed standing at the firstmain surface 5 a and are exposed at theupper surface 9 a of thecover 9 throughholes 9 h formed in thecover 9. Specifically, theholes 9 h penetrate through theframe 19 and lid 21 in directions facing the firstmain surface 5 a at the outsides of the vibration spaces S. - The first
main surface 5 a is provided with lines 23 (FIG. 2 ) connected to theSAW elements 7 and a plurality ofpads 25 connected to thelines 23. Theterminals 3 are connected to theSAW elements 7 by being provided on thepads 25. - As shown in
FIG. 3 , on the firstmain surface 5 a, aconductive layer 27 and aprotective film 29 covering theconductive layer 27 are provided. - The
conductive layer 27 forms theSAW elements 7, at least a part of the lines 23 (FIG. 2 ), and at least a part of thepads 25. Theconductive layer 27 is formed by for example an Al alloy such as an Al-Cu alloy or the like. Its thickness is for example 100 to 300 nm. - The
protective film 29 contributes to prevention of oxidation etc. of theconductive layer 27. Theprotective film 29 is formed by for example a material which has an insulating property and has a mass light enough so as not to influence the propagation of the SAW. For example, theprotective film 29 is formed by silicon oxide (SiO2 etc.), silicon nitride, silicon or the like. The thickness of theprotective film 29 is for example about 1/10 (10 nm to 30 mm) of the thickness of theconductive layer 27 or equal to or more than the thickness of the conductive layer 27 (100 nm to 300 nm). - The
protective film 29 is for example provided over generally the entire firstmain surface 5 a, while thecover 9 is laminated over theprotective film 29. Further, also the part of theresin film 11 which is on the firstmain surface 5 a is laminated over theprotective film 29. On the other hand, at the positions of arrangement of theterminals 3, theprotective film 29 is removed so that thepads 25 are exposed from theprotective film 29. - Note that, strictly speaking, the
cover 9 is not directly provided on the firstmain surface 5 a, but is provided on theprotective film 29 or the like. In the present example, even in a case where predetermined members, layers, etc. are indirectly provided on the main surface of thesubstrate 5 in this way and are not directly provided on the main surface of thesubstrate 5, it is sometimes expressed so that these predetermined members, layers, etc. are provided on the main surface of thesubstrate 5. This is true for the word “laminate” as well. - On the first
main surface 5 a, other than this, an insulation film which is laminated on theconductive layer 27 orprotective film 29, another conductive layer which is laminated on theconductive layer 27 with the insulation film interposed therebetween and forms a part of thelines 23, a connection strengthening layer which forms upper layer portions of thepads 25 and strengthens the connection between thepads 25 and theterminals 3, and so on may be provided as well. -
FIG. 4A toFIG. 6D are cross-sectional views for explaining the method of production of theSAW device 1. The steps are advanced in order fromFIG. 4A toFIG. 6D . - The steps explained below are realized in a so-called “wafer process”. That is, a mother board (wafer 31) which is later divided to form the
substrates 5 is formed with a thin film, processed by photolithography, etc., then is diced to form a large number of SAW devices in parallel. - Note, in
FIG. 4A toFIG. 5C , only parts corresponding to oneSAW device 1 are shown. Further, inFIG. 6A toFIG. 6D , only parts corresponding to threeSAW devices 1 are shown. The conductive layer, insulation layer, etc. change in shapes along with the progress in the process. However, common notations are used before and after the changes. In the same way, notations of the firstmain surface 5 a and secondmain surface 5 b of thesubstrate 5 are assigned to the first main surface and second main surface of thewafer 31. - As shown in
FIG. 4A , first, on the firstmain surface 5 a of thesubstrate 5, aconductive layer 27 is formed. Specifically, first, the thin film forming method such as the sputtering method, vapor deposition method, CVD (chemical vapor deposition) method, or the like is used to form a metal layer which becomes theconductive layer 27 on the firstmain surface 5 a. Next, the metal layer is patterned by photolithography etc. using a reduced protrusion exposure machine (stepper) and RIE (reactive ion etching) device. Therefore, aconductive layer 27 including theSAW elements 7, at least a part of thelines 23, and at least a part of thepads 25 is formed. - Next, as shown in
FIG. 4B , theprotective film 29 is formed. Specifically, first, a thin film which becomes theprotective film 29 is formed by the thin film forming method such as the CVD method or vapor deposition method or the like. Next, parts of the thin film are removed by the photolithography method so that parts of theconductive layer 27 which constitute thepads 25 are exposed. Accordingly, theprotective film 29 is formed. - After the
protective film 29 is formed, as shown inFIG. 4C , a thin film which becomes theframe 19 is formed. The thin film is formed by for example adhesion of a film formed by a photosensitive resin or a thin film forming method the same as that for theprotective film 29 etc. - After the thin film which becomes the
frame 19 is formed, as shown inFIG. 4D , the photolithography method is used to remove parts of the thin film and form openings which becomes the vibration spaces S and lower side portions of theholes 9 h. Further, groove portions are formed along the dicing lines, and side surfaces of theframe 19 are formed as well. That is, theframe 19 is formed from the thin film. Note that, the photolithography may be either of the positive type or the negative type. - After the
frame 19 is formed, as shown inFIG. 5A , the lid 21 is formed by the same method as the method of formation of theframe 19. Specifically, first, a thin film which becomes the lid 21 is formed. The thin film is formed by for example adhesion of a film formed by a photosensitive resin. By laminating the thin film on theframe 19, the openings of theframe 19 are closed, and the vibration spaces S are constituted. - Next, by the photolithography method, parts of the thin film are removed, and upper side portions of the
holes 9 h are formed. Further, groove portions are formed along the dicing lines, and side surfaces of theframe 19 are formed. That is, the lid 21 is formed from the thin film. Note that, the photolithography may be either of the positive type or negative type. - After the lid 21 is formed, as shown in
FIG. 5D ,terminals 3 are formed. Specifically, first, abase layer 33 is formed over theupper face 9 a of thecover 9 and the inside of theholes 9 h. Thebase layer 33 is a metal layer and is formed by for example the sputtering method. - Next, on the
base layer 33, a resistlayer 37 is formed. The resistlayer 37 is for example formed by having a thin film formed on the substrate by a spin coating method or other technique and having that thin film patterned by the photolithography method. By removal of parts of the thin film by patterning, thebase layer 33 is exposed at theholes 9 h and their peripheral parts. - After that, the electroplating method is used to cause a metal to deposit on the exposed parts of the
base layer 33. Accordingly,solid parts 35 are formed. - After the
solid parts 35 are formed, as shown inFIG. 5C , the parts of thebase layer 33 covered by the resistlayer 37 and the resistlayer 37 are removed. Therefore, theterminals 3 are formed. That is, the surface parts of theterminals 3 are constituted by thebase layer 33, and internal parts (majority) of theterminals 3 are constituted by thesolid parts 35. Note that, inFIG. 3 , illustration of thebase layer 33 is omitted. - After that, on the second
main surface 5 b, theback surface electrode 13 andresin layer 15 are sequentially formed (FIG. 5C ). Specifically, theback surface electrode 13 is formed by the thin film forming method such as the sputtering method, vapor deposition method, CVD method, or the like. Theresin layer 15 is formed by for example adhering a resin sheet to theback surface electrode 13, and then thermosetting it. Note that, theresin layer 15 may be formed by a potting method or printing method as well. - After the
resin layer 15 is formed, as shown inFIG. 6A , theresin layer 15 of the waferstate SAW devices 1 and a dicingtape 39 are bonded. - Next, as shown in
FIG. 6D , afirst blade 41 is used to the portions of thewafer 31 on the firstmain surface 5 a side along the dicing lines. Accordingly,groove portions 31 a partitioning a plurality ofSAW devices 1 are formed. - After the
groove portions 31 a are formed, as shown inFIG. 6C , resin constituting theresin film 11 is filled in thegroove portions 31 a. The resin is filled by using for example adispenser 43. Further, the filled resin is cured by heating. - After the resin is filled and hardened, as shown in
FIG. 6D , asecond blade 45 having a thinner blade thickness than thefirst blade 41 is used to cut the wafer-state SAW devices 1 along thegroove portions 31 a from the firstmain surface 5 a side. Specifically, the resin filled in thegroove portions 31 a, parts of thewafer 31 at the secondmain surface 5 b side, theback surface electrode 13, and theresin layer 15 are cut at schematically the center of thegroove portions 31 a. - Therefore, the plurality of
SAW devices 1 are separated from each other. Further, due to the difference of blade thickness between thefirst blade 41 and thesecond blade 45, the protrudingportions 5 d are formed. For example, when the blade thickness of thefirst blade 41 is 50 μm and the blade thickness of the second blade is 40 μm, the amount of protrusion of the protrudingportions 5 d is (50−40)/2=5 μm. - Note that, the
first blade 41 is for example a fixed abrasive type blade and has a plurality of fixedabrasive grains 41 a and a connectingmaterial 41 b holding the plurality of fixedabrasive grains 41 a. In the same way, thesecond blade 45 has a plurality of fixedabrasive grains 45 a and a connectingmaterial 45 b holding the plurality of fixedabrasive grains 45 a. - The material of the abrasive grains, particle size, the density of the abrasive grains, the material of the connecting material, and blade thickness may be suitably selected. Part of the conditions other than the blade thickness may be shared between the
first blade 41 and thesecond blade 45. For example, between thefirst blade 41 and thesecond blade 45, the material of the abrasive grains, particle size, and the density of abrasive grains are shared, but the type of the connecting material is different. As the connectingmaterial 41 b, one suitable for cutting a piezoelectric substrate (substrate 5) is selected, while as the connectingmaterial 45 b, one suitable for cutting a resin (at least one of theresin film 11 and resin layer 15) is selected. - According to the above embodiment, each
SAW device 1 has asubstrate 5 andSAW elements 7 on the firstmain surface 5 a of thesubstrate 5. On the side surfaces 5 c of thesubstrate 5, a protrudingportion 5 d is provided at the secondmain surface 5 b side compared with the firstmain surface 5 a. - Accordingly, at the time of transport etc. of the
SAW device 1, when shock is applied to aside surface 5 c, the protrudingportion 5 d is more easily impacted than the part of theside surface 5 c at the firstmain surface 5 a side. On the other hand, for maintaining the performance of theSAW device 1, rather than maintaining the shape of the part at the secondmain surface 5 b side, maintaining the shape of the part at the firstmain surface 5 a side is more important. Accordingly, this means that theSAW device 1 is improved in shock resistance from the side direction of thesubstrate 5 as a whole. Specifically, by strengthening of protection of thesubstrate 5 at the part at the firstmain surface 5 a side against shock from the side, maintenance of the shape of the SAW elements 7 (maintenance of filter precision) and maintenance of adhesion between thecover 9 and the substrate 5 (protective film 29) (antioxidation effect of conductive layer) are improved. Note that,Patent Literature 1 does not disclose the idea of protecting the firstmain surface 5 a side against the impact from the side surface with priority over the secondmain surface 5 b side. - The protruding
portion 5 d is provided along the outer circumference of the secondmain surface 5 b. Accordingly, it is possible to strengthen the protection of the firstmain surface 5 a side against impact from various directions parallel to the firstmain surface 5 a. Further, as explained with reference toFIG. 6B andFIG. 6D , the protrudingportion 5 d can be formed by a simple and convenient method of changing the cutting width at the time of dicing, for example, the protrudingportion 5 d can be formed by using thefirst blade 41 andsecond blade 45 having different blade thicknesses. - The
SAW device 1 has theresin layer 11 which covers the side surfaces 5 c at the parts of the firstmain surface 5 a side other than the protrudingportion 5 d, abuts against the protrudingportion 5 d from the firstmain surface 5 a side, and is softer than thesubstrate 5. Accordingly, due to theresin film 11, shock with respect to aside surface 5 c can be absorbed, and protection of the parts of theSAW device 1 at the firstmain surface 5 a side can be strengthened. Note that, a “resin film 11 which is softer than thesubstrate 5” means “softer” when compared in Young's modulus. That is, theresin film 11 has a smaller Young's modulus than thesubstrate 5. Further, the protrudingportion 5 d functions as a stopper which limits movement of theresin film 11 to the secondmain surface 5 b side, whereby peeling of theresin film 11 from the side surfaces 5 c is suppressed. - The
resin film 11 may also be formed so that its side surfaces are located at the inner side compared with the protrudingportion 5 d. In other words, the protrudingportion 5 d may be formed so that it protrudes outward compared with the side surfaces of theresin film 11. Due to this, when an object having a surface parallel to a side surface strikes aSAW device 1 from the side direction of thesubstrate 5, that object strikes the protrudingportion 5 d, so propagation of a large impact to the firstmain surface 5 a of theSAW device 1 can be suppressed. On the other hand, when a pointed object that does not contact the protrudingportion 5 d strikes theSAW device 1 from the side direction of thesubstrate 5, the shock at the time of impact is eased by theresin film 11, so propagation of a large shock to the firstmain surface 5 a of theSAW device 1 can again be suppressed. - The
SAW device 1 has thecover 9 which is provided on the firstmain surface 5 a and seals theSAW elements 7. The side surfaces 9 c of thecover 9 form steps by being positioned at the inner sides from the side surfaces 5 c of thesubstrate 5. Theresin film 11 is provided so as to straddle the side surfaces 9 c of thecover 9 from the side surfaces 5 c of thesubstrate 5 and abuts against the steps from the firstmain surface 5 a side. Accordingly, by covering of mating parts of thecover 9 and substrate 5 (strictly speaking, protective film 29) by theresin film 11, invasion of moisture from the mating parts and peeling of thecover 9 from thesubstrate 5 are suppressed. Further, the steps formed by thecover 9 andsubstrate 5 function as stoppers which limit movement of theresin film 11 to the secondmain surface 5 b side, so peeling of theresin film 11 from theside surface 9 c andside surface 5 c is suppressed. - Further, the method of production of the
SAW device 1 has a first cutting step (FIG. 6B ) of cutting thewafer 31, on the firstmain surface 5 a of which a plurality ofSAW elements 7 are provided, at the parts of the firstmain surface 5 a sides by thefirst blade 41 so as to formgroove portions 31 a for partitioning the plurality ofSAW devices 1. Further, this method of production has a second cutting step (FIG. 6D ) of cutting thewafer 31 at parts of the secondmain surface 5 b sides along thegroove portions 31 a by thesecond blade 45 having a thinner blade thickness than thefirst blade 41 so as to separate thewafer 31. - Accordingly, the protruding
portions 5 d can be simply formed. Further, blades which are different from each other are used in the two steps, therefore blades suitable for the steps can be used. For example, in the first cutting step (FIG. 6B ), cutting is carried out at a high speed by cutting by thefirst blade 41 having the large particle size, while in the second cutting step (FIG. 6D ), chipping, which easily occurs when a blade passes through a wafer, can be suppressed by cutting by thesecond blade 45 having a small particle size. - The method of production of the
SAW device 1 further has a step (FIG. 6C ) of filling resin in thegroove portions 31 a after the first cutting step (FIG. 6B ) and before the second cutting step (FIG. 6D ). Accordingly, the above-mentionedresin film 11 which covers the side surfaces 5 c at the firstmain surface 5 a side other than the protrudingportion 5 d and adheres to the protrudingportion 5 d can be simply constituted. - The method of production of the
SAW device 1 further has a step (FIG. 5C ) of forming theresin layer 15 on the secondmain surface 5 b of thewafer 31 before the first cutting step (FIG. 6B ). Theresin layer 15 is not cut in the first cutting step (FIG. 6B ), but theresin layer 15 is cut in the second cutting step (FIG. 6D ). Accordingly, by selecting as thefirst blade 45 one suitable for cutting the piezoelectric substrate and as thesecond blade 45 selecting one suitable for cutting theresin layer 15, chipping and cracks in the secondmain surface 5 b can be suppressed. -
FIG. 7A toFIG. 7C are cross-sectional views showing first to third modifications of the protrudingportion 5 d. The protrudingportions 5 d of the first to third modifications are formed tapered so as to spread further outward toward the secondmain surface 5 b side. In other words, the protrudingportions 5 d of the first to third modifications protrude out further the more toward the secondmain surface 5 b sides (the closer in position to the secondmain surfaces 5 b). - More specifically, in the first modification shown in
FIG. 7A , the protrudingportion 5 d is formed so that its cross-sectional shape becomes a generally right triangle. In the second modification shown inFIG. 7B , the protrudingportion 5 d is formed so that its cross-sectional shape becomes generally trapezoidal. In the third modification shown inFIG. 7C , the protrudingportion 5 d is formed so that the cross-sectional shape of the part at the firstmain surface 5 a side is generally rectangular (square) and the cross-sectional shape of the part at the secondmain surface 5 b side is generally trapezoidal. The angle of inclination of the tapered surface (5 e) of the protrudingportion 5 d relative to theside surface 5 c (defined as 0° when the tapered surface is parallel to theside surface 5 c) is for example 5° to 40°. - Note that, in the first to third modifications, the protruding
portion 5 d may be provided along the outer circumference of the secondmain surface 5 b, theresin film 11 which abuts against the protrudingportion 5 d from the firstmain surface 5 a side may be provided, and so on in the same way as the above embodiment. - The protruding
portion 5 d in the first modification can relieve stress concentration at the base of the protrudingportion 5 d at the firstmain surface 5 a side compared with the protrudingportion 5 d in the above embodiment, while can cause the positions where impact occurs to concentrate at the secondmain surface 5 b side. Further, compared with the protrudingportion 5 d in the above embodiment, the protrudingportions 5 d in the second and third modifications can cause the positions where impact occurs to concentrate at the secondmain surface 5 b side. The protrudingportions 5 d in the first to third modifications can be formed by for example forming the entiresecond blade 45 or its outer circumferential edge to be tapered. - For the
substrates 5 in the above embodiment and first modification, concrete dimensions etc. were set and simulations were performed concerning impact. Specifically, this was as follows: - Basic dimensions of
substrate 5 -
- Lx (see
FIG. 2 ) =0.6 mm - Ly (see
FIG. 2 ) =0.8 mm - Lz (see
FIG. 2 ) =0.2 mm
- Lx (see
- Dimensions of protruding
portion 5 d -
- d1 (see
FIG. 2 andFIG. 7A ) =0.0075 mm - d2 (see
FIG. 2 andFIG. 7A ) =0.037 mm
- d1 (see
- Young's modulus of substrate 5:230 GPa (assuming LiTaO3)
- Poisson's ratio of substrate 5:0.3 (assuming LiTaO3)
- Density of substrate 5:7450 kg/m3 (assuming LiTaO3)
- Assumed situation: A situation was assumed where the
substrate 5 was dropped in a Y-direction (seeFIG. 2 ) and struck an XZ surface (surface perpendicular to Y-direction). A velocity at the time of impact of 3.2 m/s and an acceleration at the time of impact of 9.8 m/s2 (gravitational acceleration) were assumed. - The finite element method was used to calculate the stress distribution in the
substrate 5 in time sequence. - That is, when dropping the
substrate 5 in the Y-direction, the protrudingportion 5 d impacts the XZ surface whereby stress is generated at the protrudingportion 5 d. This stress is propagated to theentire substrate 5 along with the elapse of time. This situation was reproduced and the stress of each part of thesubstrate 5 at each point of time was examined. - The maximum stress generated at the first
main surface 5 a was extracted. - Reason: This is because, as explained above, for maintenance of performance of the
SAW device 1, it is considered that maintaining the shape of the part at the firstmain surface 5 a side is more important than maintaining the shape of the part at the secondmain surface 5 b side. Further, it is considered that the influence of the maximum value is greater than the mean value of stress. - Note that, the position of generation and point of time of generation in the first
main surface 5 a of the maximum stress which is generated in the firstmain surface 5 a differ according to the simulation conditions. -
- Case of the protruding
portion 5 d in the above embodiment- Maximum stress in first
main surface 5 a:2.8×108 Pa
- Maximum stress in first
- Case of protruding
portion 5 d in the first modification- Maximum stress in first
main surface 5 a:2.5×108 Pa
- Maximum stress in first
- It was confirmed from the simulation results that the maximum value of stress generated in the first
main surface 5 a was smaller in the case where the protrudingportion 5 d was tapered so as to further protrude outward toward the secondmain surface 5 b side than the case where the protrudingportion 5 d was rectangular. - The present invention is not limited to the above embodiment and modifications and may be executed in various ways.
- The acoustic wave device is not limited to a SAW device. For example, the acoustic wave device may be a film bulk acoustic resonator. Further, the acoustic wave device may be a boundary acoustic wave device utilizing a boundary acoustic wave.
- In the acoustic wave device, the resin film (11), back surface electrode (13), resin layer (15), and protective film (29) may be omitted. Conversely, other suitable layers etc. may be formed. Further, in the case of the boundary acoustic wave device, an acoustic wave device can be prepared without provision of vibration spaces S.
- Further, the shape of the protruding
portion 5 d is not limited to the above explained ones. For example, the protrudingportion 5 d may be formed so as to gradually become broader from the first main surface 3 a of thepiezoelectric substrate 3 toward the second main surface 3 b. In other words, the protrudingportion 5 d may be provided so that the shape of thepiezoelectric substrate 3 becomes generally trapezoidal when viewing it from the side surface. - The cutting of the wafer is not limited to cutting carried out by using a blade. For example, the cutting may be carried out by using a laser. Further, a plurality of methods may be combined. For example, the first cutting step may be carried out by using a blade and the second cutting step may be carried out by using a laser.
- Note that, in the SAW device, whether a side surface (5 c) at the one main surface side (5 a) other than the protruding portion (5 d) and the surface (5 e) of the protruding portion facing the side direction of the substrate are formed by surfaces cut by a blade can be identified by for example observation of the surfaces by an SEM (scanning electron microscope). For example, when a wafer is cut by a blade, straight (strictly speaking, arc-shaped) grooves which are formed by cutting by abrasive grains and are parallel to the main surface is formed in the side surface, therefore these grooves can be observed by the SEM.
- The cutting in the second cutting step (
FIG. 6D ) need not be carried out from onemain surface 5 a side (side cut in the first cutting step) or may be carried out from the othermain surface 5 b side. - In the filling step (
FIG. 6C ) of resin which forms theresin film 11, the resin need not be filled up to theupper surface 9 a of thecover 9. For example, the resin may be filled up to onemain surface 5 a of thesubstrate 5 or a part lower than it, or may be filled up to the upper face of the cover or a part lower than it. - 1 . . . SAW device (acoustic wave device), 5 . . . substrate, 5 a . . . first main surface (one main surface), 5 b . . . second main surface (other main surface), 5 c . . . side surface, 5 d . . . protruding portion, and 7 . . . SAW element (acoustic wave element).
Claims (10)
1. An acoustic wave device, comprising:
a substrate and
an acoustic wave element on one main surface of the substrate, wherein
a side surface of the substrate comprises a protruding portion which protrudes out at a side of an another main surface closer than a side of the one main surface.
2. The acoustic wave device according to claim 1 , wherein
when the side surface of the substrate are divided in a thickness direction into two regions of a first region at the side of the one main surface and a second region at the side of the another main surface, the protruding portion is provided in the second region.
3. The acoustic wave device according to claim 2 , wherein
the protruding portion is provided along an outer circumference of the other main surface and over the entire outer circumference.
4. The acoustic wave device according to claim 1 , wherein
the protruding portion is formed tapered to spread more outward toward a position near the other main surface.
5. The acoustic wave device according to claim 1 , further comprising:
a resin film which covers the side surface of the substrate at the part at the side of the one main surface other than the protruding portion, abuts against the protruding portion from the side of the one main surface, and is softer than the substrate.
6. The acoustic wave device according to claim 5 , further comprising:
a cover which is provided on the one main surface and seals the acoustic wave element, wherein
a side surface of the cover which is located at an inner side away from the side surface of the substrate and which forms a step with the substrate, and
the resin film is provided and straddles the side surface of the cover from the side surface of the substrate and abuts against the step from the side of the one main surface.
7. The acoustic wave device according to claim 1 , wherein:
the side surface of the substrate at the side of the one main surface other than the protruding portion and the surface of the protruding portion facing the side direction of the substrate are cut surfaces formed by surfaces cut by a blade.
8. A method for manufacturing an acoustic wave device, comprising:
a first cutting step of forming a groove portions which partition a plurality of acoustic wave devices by cutting with a first blade one main surface side portion of a wafer which the plurality of acoustic wave elements are provided on one main surface and
a second cutting step of cutting an other main surface side portion of the wafer along the groove portions with a second blade having a thinner blade thickness than the first blade, and separating the wafer.
9. The method for manufacturing an acoustic wave device according to claim 8 , further comprising:
a step of filling resin in the groove portions after the first cutting step and before the second cutting step.
10. The method for manufacturing an acoustic wave device according to claim 8 , further comprising:
a step of forming a resin layer on the other main surface of the wafer before the first cutting step, wherein
the resin layer is not cut in the first cutting step, and
the resin layer is cut in the second cutting step.
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US15/431,610 US20170163241A1 (en) | 2009-11-27 | 2017-02-13 | Acoustic wave device and method for producing same |
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PCT/JP2010/071154 WO2011065499A1 (en) | 2009-11-27 | 2010-11-26 | Acoustic wave device and method for manufacturing the same |
US201213498815A | 2012-03-28 | 2012-03-28 | |
US14/629,373 US9584095B2 (en) | 2009-11-27 | 2015-02-23 | Acoustic wave device and method for producing same |
US15/431,610 US20170163241A1 (en) | 2009-11-27 | 2017-02-13 | Acoustic wave device and method for producing same |
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US15/431,610 Abandoned US20170163241A1 (en) | 2009-11-27 | 2017-02-13 | Acoustic wave device and method for producing same |
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CN101803189B (en) * | 2007-10-30 | 2014-01-08 | 京瓷株式会社 | Elastic wave device |
WO2010125873A1 (en) * | 2009-04-28 | 2010-11-04 | 京セラ株式会社 | Elastic wave device and manufacturing method thereof |
CN103748787B (en) * | 2011-08-22 | 2017-04-12 | 京瓷株式会社 | Elastic wave device and electronic component |
JP5821961B2 (en) | 2011-09-02 | 2015-11-24 | 株式会社村田製作所 | Composite circuit module |
CN104798302B (en) * | 2012-12-05 | 2017-07-07 | 株式会社村田制作所 | The manufacture method and acoustic wave device of acoustic wave device |
US9793877B2 (en) * | 2013-12-17 | 2017-10-17 | Avago Technologies General Ip (Singapore) Pte. Ltd. | Encapsulated bulk acoustic wave (BAW) resonator device |
USD760230S1 (en) | 2014-09-16 | 2016-06-28 | Daishinku Corporation | Piezoelectric vibration device |
WO2017110308A1 (en) * | 2015-12-21 | 2017-06-29 | 株式会社村田製作所 | Acoustic wave device |
CN111052607B (en) * | 2017-08-31 | 2023-10-17 | 株式会社村田制作所 | Elastic wave device and elastic wave module provided with same |
JP7037333B2 (en) * | 2017-11-13 | 2022-03-16 | 太陽誘電株式会社 | Elastic wave devices and their manufacturing methods, filters and multiplexers |
JP7373305B2 (en) * | 2019-05-23 | 2023-11-02 | 太陽誘電株式会社 | Acoustic wave device and its manufacturing method |
US20220173722A1 (en) * | 2022-02-18 | 2022-06-02 | Newsonic Technologies | Surface acoustic wave resonator, filter, and communication device |
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JPH06103820B2 (en) * | 1989-05-19 | 1994-12-14 | 三洋電機株式会社 | Method for manufacturing surface acoustic wave element |
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JP2002261582A (en) * | 2000-10-04 | 2002-09-13 | Matsushita Electric Ind Co Ltd | Surface acoustic wave device, its manufacturing method, and circuit module using the same |
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- 2010-11-26 JP JP2011543330A patent/JP5339313B2/en active Active
- 2010-11-26 CN CN201080042265.8A patent/CN102577119B/en active Active
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- 2010-11-26 WO PCT/JP2010/071154 patent/WO2011065499A1/en active Application Filing
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US20120182091A1 (en) | 2012-07-19 |
WO2011065499A1 (en) | 2011-06-03 |
US9584095B2 (en) | 2017-02-28 |
CN102577119A (en) | 2012-07-11 |
JPWO2011065499A1 (en) | 2013-04-18 |
CN102577119B (en) | 2015-04-29 |
US8963655B2 (en) | 2015-02-24 |
US20150171825A1 (en) | 2015-06-18 |
JP5339313B2 (en) | 2013-11-13 |
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