US20010011857A1 - Surface acoustic wave device and method for fabricating the same - Google Patents
Surface acoustic wave device and method for fabricating the same Download PDFInfo
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- US20010011857A1 US20010011857A1 US09/231,836 US23183699A US2001011857A1 US 20010011857 A1 US20010011857 A1 US 20010011857A1 US 23183699 A US23183699 A US 23183699A US 2001011857 A1 US2001011857 A1 US 2001011857A1
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- Prior art keywords
- acoustic wave
- surface acoustic
- insulating film
- piezoelectric substrate
- wave device
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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
- H03H9/1064—Mounting in enclosures for surface acoustic wave [SAW] devices
- H03H9/1092—Mounting in enclosures for surface acoustic wave [SAW] devices the enclosure being defined by a cover cap mounted on an element forming part of the surface acoustic wave [SAW] device on the side of the IDT's
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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
- H03H9/058—Holders; Supports for surface acoustic wave devices
- H03H9/059—Holders; Supports for surface acoustic wave devices consisting of mounting pads or bumps
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/10—Bump connectors; Manufacturing methods related thereto
- H01L2224/15—Structure, shape, material or disposition of the bump connectors after the connecting process
- H01L2224/16—Structure, shape, material or disposition of the bump connectors after the connecting process of an individual bump connector
- H01L2224/161—Disposition
- H01L2224/16151—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive
- H01L2224/16221—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked
- H01L2224/16225—Disposition the bump connector connecting between a semiconductor or solid-state body and an item not being a semiconductor or solid-state body, e.g. chip-to-substrate, chip-to-passive the body and the item being stacked the item being non-metallic, e.g. insulating substrate with or without metallisation
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2224/00—Indexing scheme for arrangements for connecting or disconnecting semiconductor or solid-state bodies and methods related thereto as covered by H01L24/00
- H01L2224/01—Means for bonding being attached to, or being formed on, the surface to be connected, e.g. chip-to-package, die-attach, "first-level" interconnects; Manufacturing methods related thereto
- H01L2224/42—Wire connectors; Manufacturing methods related thereto
- H01L2224/47—Structure, shape, material or disposition of the wire connectors after the connecting process
- H01L2224/48—Structure, shape, material or disposition of the wire connectors after the connecting process of an individual wire connector
- H01L2224/4805—Shape
- H01L2224/4809—Loop shape
- H01L2224/48091—Arched
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L2924/00—Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
- H01L2924/15—Details of package parts other than the semiconductor or other solid state devices to be connected
- H01L2924/161—Cap
- H01L2924/1615—Shape
- H01L2924/16195—Flat cap [not enclosing an internal cavity]
Definitions
- the present invention relates to a surface acoustic wave device used as a high-frequency oscillator in telecommunication equipment as well as to a method for fabricating the device.
- FIG. 10 is a cross-sectional view of a conventional surface acoustic wave device.
- reference numeral 1 denotes a piezoelectric substrate (called the chip hereunder) constituting a surface acoustic wave element.
- the chip On a principal plane of the chip 1 (upper surface in FIG. 10) are a surface acoustic wave functional portion 1 a and electrode pads (the latter not shown).
- the functional portion 1 a comprises driving electrodes made of known finger-shaped inter-digital transducers (called IDTs hereunder), and propagation paths for surface waves driven in a predetermined direction on the chip surface.
- the electrode pads extend from the driving electrodes and serve as external connection terminals of the functional portion 1 a.
- Reference numeral 12 denotes a package that holds the chip 1
- 12 a and 12 b denote package side walls that surround the chip thereby constituting a chip holder.
- Part of the side wall 12 a includes a terminal portion 12 c serving as external connectors.
- Reference numeral 4 denotes wires for electrically connecting the electrode pads of the functional portion 1 a to the terminal portion 12 c.
- Reference numeral 11 denotes a metal cover connected to a sealing portion 12 d placed on the top surface of the package side wall 12 b , whereby the functional portion 1 a of the chip 1 is sealed in an airtight and protected manner.
- the surface acoustic wave device In order to release acoustically both the surface waves driven by the known IDTs and the propagation paths for the waves, the surface acoustic wave device requires that a hollow portion be secured over the surface of the functional portion 1 a and that protective measures be taken to prevent breakdown of the functional portion 1 a.
- FIG. 11 is a cross-sectional view of another conventional surface acoustic wave device disclosed in Japanese Patent Application Laid-open No. (Hei)4-301910.
- Hei Japanese Patent Application Laid-open No.
- the device in FIG. 11 has the functional portion 1 a furnished at the bottom of the chip 1 , with a hollow portion formed between the functional portion 1 a and the package 12 .
- Bump electrodes 6 connect the functional portion 1 a with the terminal portion 12 c . That is, electrical connections between the portions 1 a and 12 c are secured by connecting the bump electrodes 6 , formed on electrode pads not shown, to the terminal portion 12 c .
- the package side wall 12 a creates a stagger for a portion opposite to the functional portion 1 a and also contributes to providing the hollow portion 9 .
- the setup protects the functional portion 1 a and secures a clearance over its surface.
- the metal cover 11 on top of the chip 1 seals the opening of the package 12 airtight with the sealing portion 12 d interposed therebetween.
- a surface acoustic wave device having surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on one principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, a frame-like first insulating film furnished on the one principal plane of the piezoelectric substrate so as to surround the functional portion and a lid-like second insulating film for covering the driving electrodes and surface wave propagation paths of the functional portion while securing a predetermined space over the functional portion.
- the surface acoustic wave device may further comprise bump electrodes which are formed on either the one principal plane or other principal plane of the piezoelectric substrate and which constitute external connectors of the surface acoustic wave elements, wherein the surface acoustic wave elements are connected via the bump elements to the circuit substrate in flip-chip bonding fashion.
- a surface acoustic wave device having surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on one principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, bump electrodes which are formed on the one principal plane of the piezoelectric substrate and which constitute external connectors of the functional portion and an first insulating film deposited on the one principal plane of the piezoelectric substrate except where there exist at least the functional portion and the bump electrodes, wherein the bump electrodes of the surface acoustic wave elements are connected to the circuit substrate in flip-chip bonding fashion, with an anisotropic conductor interposed between the bump electrodes and the circuit substrate.
- the surface acoustic wave device may further comprise a second insulating film deposited on the first insulating film so as to secure a predetermined space over the functional portion while covering the driving electrodes and surface wave propagation paths of the functional portion except where there exist at least the bump electrodes.
- a method for fabricating a surface acoustic wave device comprises the steps of forming functional portions of a plurality of surface acoustic wave elements on one principal plane of a piezoelectric substrate, the function portions including driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, depositing a first insulating film on the one principal plane of the piezoelectric substrate except where there exist at least the functional portions and electrode pads for use by bump electrodes, depositing a second insulating film in lid fashion over the functional portions except where there exist at least the electrode pads on the first insulating film so as to secure a predetermined space while covering the driving electrodes and surface wave propagation paths of the functional portions, furnishing each of the functional portions with the bump electrodes constituting external connectors of the functional portions on the one principal plane of the piezoelectric substrate, providing a single anisotropic conductor so as to cover the plurality of the functional portions and
- FIG. 1 is a cross-sectional view of a surface acoustic wave device according to embodiment 1 of the present invention.
- FIG. 2 is a cross-sectional view of a surface acoustic wave device according to embodiment 2 of the present invention.
- FIGS. 3A to 3 F are schematic views showing steps to fabricate a chip for use by a surface acoustic wave device according to embodiment 3 of the present invention.
- FIGS. 4A and 4B are perspective views illustrating respectively typical states of the chips in FIGS. 3D and 3F as they are being fabricated.
- FIG. 5 is a cross-sectional view of a surface acoustic wave device according to embodiment 4 of the present invention.
- FIG. 6 is a cross-sectional view of a surface acoustic wave device according to embodiment 5 of the present invention.
- FIG. 7 is a plan view of a chip 1 used by the embodiment 5 of the present invention.
- FIG. 8 is a cross-sectional view of a surface acoustic wave device according to embodiment 6 of the present invention.
- FIGS. 9A to 9 F are schematic views showing steps to fabricate a chip for use by a surface acoustic wave device, the steps constituting a method according to embodiment 7 of the present invention.
- FIG. 10 is a cross-sectional view of a conventional surface acoustic wave device.
- FIG. 11 is a cross-sectional view of another conventional surface acoustic wave device disclosed in Japanese Patent Application Laid-open No. (Hei) 4-301910.
- FIG. 1 is a cross-sectional view of a surface acoustic wave device according to embodiment 1.
- reference numeral 1 denotes a piezoelectric substrate chip constituting a surface acoustic wave element.
- On a principal plane of the chip 1 (upper surface in FIG. 1) are a surface acoustic wave functional portion 1 a and electrode pads.
- the functional portion 1 a comprises driving electrodes made of known IDTs, and propagation paths for surface waves driven in a predetermined direction on the chip surface.
- the electrode pads, not shown, extend from the driving electrodes and serve as external connection terminals of the functional portion 1 a.
- Reference numeral 3 denotes a circuit substrate on which to mount the chip; 3 c for a terminal portion formed on a part of the circuit substrate 3 ; 4 for wires that connect the electrode pads of the functional portion 1 a electrically to the terminal portion 3 c ; 2 a for a frame-like first insulating film deposited on the upper surface of the chip 1 surrounding the functional portion 1 a on the chip 1 ; and 2 b for a lid-like second insulating film attached to the first insulating film 2 a in covering relation therewith.
- the second insulating film 2 b ensures a suitable hollow portion 9 over the functional portion 1 a and protectively envelopes the driving electrodes and surface acoustic wave propagation paths of the functional portion 1 a.
- the crucially important functional portion 1 a is protected by the first and the second insulating film 2 a and 2 b with the hollow portion 9 interposed therebetween.
- the makeup allows the chip 1 to be fabricated in a secure manner with little risk of getting the functional portion 1 a inadvertently damaged during the process.
- first and the second insulating film 2 a and 2 b seal the functional portion 1 a in a simplified fashion, it is not mandatory, as with conventional surface acoustic wave devices, to provide costly airtight sealing on the functional portion. The result is an inexpensively manufactured surface acoustic wave device.
- FIG. 2 is a cross-sectional view of a surface acoustic wave device according to embodiment 2.
- FIG. 2 those parts with their counterparts already shown in FIG. 1 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive.
- reference numeral 5 represents an insulating resin.
- the chip 1 with its functional portion 1 a capped by the first and the second insulating film 2 a and 2 b , is mounted on the circuit substrate 3 .
- Metal wires 4 are used to connect the functional portion 1 a electrically to the terminal portion 3 c .
- the insulating resin 5 is deposited so as to cover the chip 1 and metal wires 4 . This makeup ensures the same effects as the embodiment 1 and provides a surface acoustic wave device still more reliable than the embodiment 1.
- FIGS. 3A to 3 F are schematic views showing steps to fabricate a chip for use by a surface acoustic wave device according to the embodiment 3.
- FIGS. 4A and 4B are perspective views illustrating respectively typical states of the chips in FIGS. 3D and 3F as they are being fabricated.
- FIG. 3A shows a wafer 30 .
- a plurality of functional portions 1 a are formed through conductor patterning at suitable intervals as indicated in FIG. 3B.
- a photosensitive film 40 is then deposited on all functional portions 1 a on the wafer 30 as illustrated in FIG. 3C. With the film 40 in place, a frame-like first insulating film 2 a is formed by photolithography so as to surround each functional portion as shown in FIGS. 3D and 4A.
- FIG. 4A depicts a case in which two functional portions 1 a are surrounded by the first insulating film 2 a.
- a single photosensitive film 50 is deposited on the first insulating film 2 a over the wafer as illustrated in FIG. 3E.
- the process creates a suitable hollow portion 9 between each functional part 1 a and the photosensitive film 50 .
- a lid-like second insulating film 2 b is formed also by photolithography (as in FIGS. 3D and 4A) to cover each of the first insulating films 2 a as depicted in FIG. 3F and 4B.
- the wafer is diced up along separation lines 60 separating chips as shown in FIGS. 4A and 4B, whereby the individual chips are formed.
- the embodiment 3 of the invention has its first and second insulating films fabricated finely, precisely and efficiently, the films offering the same effects as those of the first and the embodiment 2.
- FIG. 5 is a cross-sectional view of a surface acoustic wave device according to embodiment 4.
- those parts with their counterparts already shown in FIG. 1 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive.
- reference numeral 6 denotes bump electrodes constituting external connectors of the functional portion 1 a.
- the chip 1 with its functional portion 1 a capped by the first and the second insulating film 2 a and 2 b , is connected by the bump electrodes 6 to suitable connectors 3 c on the circuit substrate 3 in flip-chip bonding fashion.
- the embodiment 4 may be fabricated as a surface acoustic wave device with significantly enhanced reliability.
- FIG. 6 is a cross-sectional view of a surface acoustic wave device according to the embodiment 5.
- FIG. 7 is a plan view of a chip 1 used by the embodiment 5.
- FIGS. 6 and 7 those parts with their counterparts already shown in FIG. 1 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive.
- an insulating film 7 is formed over the chip 1 except where there are at least the functional portion 1 a and the electrode pads 10 constituting external connectors of the functional portion 1 a.
- the thickness of the insulating film 7 should preferably be made equal to or slightly less than that of the bump electrodes 6 as depicted in FIG. 6.
- the chip 1 is mounted on the bump electrodes 6 so that a hollow portion 9 is secured over its functional portion 1 a as shown in FIG. 6.
- the chip 1 is then connected to suitable connectors 3 c on the circuit substrate 3 in flip-chip bonding fashion, with an anisotropic conductor 8 interposed between the bump electrodes 6 and the connectors 3 c.
- the chip 1 is bonded to the circuit substrate 3 not only via the bump electrodes 6 but also through the insulating film 7 .
- This setup prevents junction stress from getting concentrated locally, thereby implementing a surface acoustic wave device with its bump electrodes 6 offering high connection reliability.
- the embodiment 5 may also be fabricated as a surface acoustic wave device with significantly enhanced reliability.
- the embodiment 5 will have its insulating film 7 fabricated finely, precisely and efficiently.
- FIG. 8 is a cross-sectional view of a surface acoustic wave device according to embodiment 6.
- those parts with their counterparts already shown in FIG. 1 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive.
- a first insulating film 7 a is formed over the chip 1 except where there are at least the functional portion 1 a and bump electrode pads 10 .
- a second insulating film 7 b is deposited on the first insulating film 7 a .
- the functional portion 1 a of the chip 1 is covered with the first and the second insulating film 7 a and 7 b in such a manner that a hollow portion 9 is secured over the surface of the functional part 1 a.
- Those parts of the films 7 a and 7 b which correspond to the electrode pads 10 are removed so that the bump electrodes 6 are exposed.
- the combined thickness of the first and the second insulating film 7 a and 7 b should preferably be made identical to or slightly less than the height of the bump electrodes 6 .
- the chip 1 is connected by the bump electrodes 6 to suitable connectors 3 c on the circuit substrate 3 in flip-chip bonding fashion, with the anisotropic conductor 8 interposed between the bump electrodes 6 and the connectors 3 c.
- the embodiment 6 of the above constitution provides the same effects as the embodiment 5. Because the crucially important functional portion 1 a is protected by the first and the second insulating film 7 a and 7 b with the hollow portion interposed therebetween, the above makeup allows the chip 1 to be fabricated in a secure manner with little risk of getting the functional portion 1 a inadvertently damaged during the process.
- first and the second insulating film 7 a and 7 b seal the functional portion 1 a in a simplified fashion, it is not mandatory, as with conventional surface acoustic wave devices, to provide costly airtight sealing on the functional portion. This makes it possible to manufacture an inexpensive yet viable surface acoustic wave device.
- the embodiment 6 may also be fabricated as a surface acoustic wave device with significantly enhanced reliability.
- the embodiment 6 will have its first and second insulating films 7 a and 7 b fabricated finely, precisely and efficiently.
- FIGS. 9A to 9 F are schematic views showing steps to fabricate a chip for use by a surface acoustic wave device, the steps constituting a method according to embodiment 7.
- FIG. 9A shows a wafer 30 .
- a plurality of functional portions 1 a are formed through conductor patterning at suitable intervals as depicted in FIG. 9B.
- a first insulating film 7 a made illustratively of a photosensitive material is then deposited on the wafer surface comprising the functional portions 1 a.
- the first insulating film 7 a is shaped as shown in FIG. 9C by photolithography, with the functional portions 1 a and electrode pads for bump electrodes excluded.
- a second insulating film 7 b composed of a photosensitive material is further deposited on the first insulating film 7 a .
- a lid covering the functional portions 1 a is formed by similar photolithography. With the electrode pads for bump electrodes excluded, the second insulating film 7 b is then formed as shown in FIG. 9C.
- the bump electrodes 6 corresponding to each of the functional portions are furnished as illustrated in FIG. 9D.
- the combined thickness of the first and the second insulating film 7 a and 7 b should preferably be made identical to or slightly less than the height of the bump electrodes 6 .
- a single anisotropic conductor 8 is furnished so as to cover all functional portions and their bump electrodes 6 , the conductor being in contact with the bump electrodes.
- the wafer is diced up along separation lines 60 separating chips as shown in FIG. 9F, whereby the individual chips are formed.
- the surface acoustic wave device of the present invention has surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on a principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, a frame-like first insulating film furnished on the principal plane of the piezoelectric substrate so as to surround the functional portion and a lid-like second insulating film for covering the driving electrodes and surface wave propagation paths of the functional portion while securing a predetermined space over the functional portion.
- This structure provides a hollow portion over the surface of the functional portions so that the device is fabricated in secure, damage-free fashion.
- the surfaces of the surface acoustic wave elements may be covered with an insulating resin. This makes it possible to fabricate a more reliable surface acoustic wave device than before.
- the surface acoustic wave device of the present invention may further comprise bump electrodes which are formed on either one principal plane or another principal plane of the piezoelectric substrate and which constitute external connectors of the surface acoustic wave elements, wherein the surface acoustic wave elements are connected via the bump elements to the circuit substrate in flip-chip bonding fashion.
- This preferred structure helps reduce the size of the surface acoustic wave device.
- the surface acoustic wave device of the present invention has surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on a principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, bump electrodes which are formed on the principal plane of the piezoelectric substrate and which constitute external connectors of the functional portion and an insulating film deposited on the principal plane of the piezoelectric substrate except where there exist at least the functional portion and the bump electrodes, wherein the surface acoustic wave elements are connected via the bump electrodes to the circuit substrate in flip-chip bonding fashion, with an anisotropic conductor interposed between the bump electrodes and the circuit substrate.
- This structure prevents junction stress from getting concentrated locally on the chip, allowing the bump electrodes to offer high connection reliability.
- the surface acoustic wave device of the present invention has surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on a principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, a first insulating film deposited on the principal plane of the piezoelectric substrate except where there exist at least the functional portion and bump electrodes and a second insulating film deposited on the first insulating film so as to secure a predetermined space over the functional portion while covering the driving electrodes and surface wave propagation paths of the functional portion except where there exist at least the bump electrodes, wherein the surface acoustic wave elements are connected via the bump electrodes to the circuit substrate in flip-chip bonding fashion, with an anisotropic conductor interposed between the bump electrodes and the circuit substrate.
- This structure reinforces protection of the functional portions and eliminates the need for
- the first and the second insulating film of the surface acoustic wave device may be composed of photosensitive films and formed by photolithography. This structure allows the insulating films to be fabricated finely, precisely and efficiently.
- a method for fabricating a surface acoustic wave device of the present invention comprises the steps of forming functional portions of a plurality of surface acoustic wave elements on one principal plane of a piezoelectric substrate, the function portions including driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, depositing a first insulating film on the principal plane of the piezoelectric substrate except where there exist at least the functional portions and electrode pads for use by bump electrodes, depositing on the first insulating film a second insulating film in lid fashion covering each of the functional portions except each of the electrode pads so as to secure a predetermined space over the functional portions while covering the driving electrodes and surface wave propagation paths of the functional portions, furnishing each of the functional portions with the bump electrodes constituting external connectors of the functional portions on the principal plane of the piezoelectric substrate, providing a single anisotropic conductor so as to cover the plurality of functional portions and each of the bump electrodes, connecting the bump electrodes to the
- the inventive method may further comprise the steps of having the first and the second insulating film composed of photosensitive films and formed by photolithography.
- the additional steps make it possible to fabricate the insulating films finely, precisely and efficiently.
Abstract
A surface acoustic wave device that is small, lightweight and highly reliable, and protects its functional portion. The surface acoustic wave device has surface acoustic wave elements mounted on a circuit substrate. Each surface acoustic wave element includes a frame-like first insulating film furnished to surround functional portions on a chip, and a lid-like second insulating film deposited on the first insulating film so as to cover driving electrodes and surface wave propagation paths of the functional portions, while securing a hollow portion over the functional portions.
Description
- 1. Field of the Invention
- The present invention relates to a surface acoustic wave device used as a high-frequency oscillator in telecommunication equipment as well as to a method for fabricating the device.
- 2. Description of Related Art
- FIG. 10 is a cross-sectional view of a conventional surface acoustic wave device. In FIG. 10,
reference numeral 1 denotes a piezoelectric substrate (called the chip hereunder) constituting a surface acoustic wave element. On a principal plane of the chip 1 (upper surface in FIG. 10) are a surface acoustic wavefunctional portion 1 a and electrode pads (the latter not shown). Thefunctional portion 1 a comprises driving electrodes made of known finger-shaped inter-digital transducers (called IDTs hereunder), and propagation paths for surface waves driven in a predetermined direction on the chip surface. The electrode pads extend from the driving electrodes and serve as external connection terminals of thefunctional portion 1 a.Reference numeral 12 denotes a package that holds thechip side wall 12 a includes aterminal portion 12 c serving as external connectors.Reference numeral 4 denotes wires for electrically connecting the electrode pads of thefunctional portion 1 a to theterminal portion 12 c. -
Reference numeral 11 denotes a metal cover connected to asealing portion 12 d placed on the top surface of thepackage side wall 12 b, whereby thefunctional portion 1 a of thechip 1 is sealed in an airtight and protected manner. In order to release acoustically both the surface waves driven by the known IDTs and the propagation paths for the waves, the surface acoustic wave device requires that a hollow portion be secured over the surface of thefunctional portion 1 a and that protective measures be taken to prevent breakdown of thefunctional portion 1 a. - FIG. 11 is a cross-sectional view of another conventional surface acoustic wave device disclosed in Japanese Patent Application Laid-open No. (Hei)4-301910. In FIG. 11, those parts with their counterparts already shown in FIG. 10 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive.
- The device in FIG. 11 has the
functional portion 1 a furnished at the bottom of thechip 1, with a hollow portion formed between thefunctional portion 1 a and thepackage 12.Bump electrodes 6 connect thefunctional portion 1 a with theterminal portion 12 c. That is, electrical connections between theportions bump electrodes 6, formed on electrode pads not shown, to theterminal portion 12 c. Thepackage side wall 12 a creates a stagger for a portion opposite to thefunctional portion 1 a and also contributes to providing thehollow portion 9. The setup protects thefunctional portion 1 a and secures a clearance over its surface. As in the case of the device in FIG. 10, themetal cover 11 on top of thechip 1 seals the opening of thepackage 12 airtight with the sealingportion 12 d interposed therebetween. - Conventional surface acoustic wave devices are typically constituted as outlined above. In such devices, the
cover 11 made of metal has been used for airtight sealing. When an alternative insulating resin, although less expensive, is used to surround thechip 1 periphery, the resin adheres on thechip 1 and makes it impossible to secure a hollow portion over the surface of thefunctional portion 1 a. Meanwhile, the use of the metal cover pushed up manufacturing costs of the surface acoustic wave device, a disadvantage that has plagued the prior art. - It is therefore an object of the present invention to overcome the above and other deficiencies of the prior art and to provide a surface acoustic wave device that is small, lightweight, highly reliable, and is protected against breakdown of its functional portion with a hollow segment secured over the surface of that functional portion.
- It is another object of the present invention to provide a method for fabricating a surface acoustic wave device in ways that are simpler, more efficient, more accurate and less expensive than before.
- According to a first aspect of the present invention, there is provided a surface acoustic wave device having surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on one principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, a frame-like first insulating film furnished on the one principal plane of the piezoelectric substrate so as to surround the functional portion and a lid-like second insulating film for covering the driving electrodes and surface wave propagation paths of the functional portion while securing a predetermined space over the functional portion.
- Here, the surface acoustic wave device may further comprise bump electrodes which are formed on either the one principal plane or other principal plane of the piezoelectric substrate and which constitute external connectors of the surface acoustic wave elements, wherein the surface acoustic wave elements are connected via the bump elements to the circuit substrate in flip-chip bonding fashion.
- According to a second aspect of the present invention, there is provided a surface acoustic wave device having surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on one principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, bump electrodes which are formed on the one principal plane of the piezoelectric substrate and which constitute external connectors of the functional portion and an first insulating film deposited on the one principal plane of the piezoelectric substrate except where there exist at least the functional portion and the bump electrodes, wherein the bump electrodes of the surface acoustic wave elements are connected to the circuit substrate in flip-chip bonding fashion, with an anisotropic conductor interposed between the bump electrodes and the circuit substrate.
- Here, the surface acoustic wave device may further comprise a second insulating film deposited on the first insulating film so as to secure a predetermined space over the functional portion while covering the driving electrodes and surface wave propagation paths of the functional portion except where there exist at least the bump electrodes.
- According to a third aspect of the present invention, there is provided a method for fabricating a surface acoustic wave device, the method comprises the steps of forming functional portions of a plurality of surface acoustic wave elements on one principal plane of a piezoelectric substrate, the function portions including driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, depositing a first insulating film on the one principal plane of the piezoelectric substrate except where there exist at least the functional portions and electrode pads for use by bump electrodes, depositing a second insulating film in lid fashion over the functional portions except where there exist at least the electrode pads on the first insulating film so as to secure a predetermined space while covering the driving electrodes and surface wave propagation paths of the functional portions, furnishing each of the functional portions with the bump electrodes constituting external connectors of the functional portions on the one principal plane of the piezoelectric substrate, providing a single anisotropic conductor so as to cover the plurality of the functional portions and each of the bump electrodes, connecting the bump electrodes to the circuit substrate in flip-chip bonding fashion and separating the surface acoustic wave elements into individual elements.
- The above and other objects, effects, features and advantages of the present invention will become more apparent from the following description of the embodiments thereof taken in conjunction with the accompanying drawings.
- FIG. 1 is a cross-sectional view of a surface acoustic wave device according to
embodiment 1 of the present invention. - FIG. 2 is a cross-sectional view of a surface acoustic wave device according to embodiment 2 of the present invention.
- FIGS. 3A to3F are schematic views showing steps to fabricate a chip for use by a surface acoustic wave device according to
embodiment 3 of the present invention. - FIGS. 4A and 4B are perspective views illustrating respectively typical states of the chips in FIGS. 3D and 3F as they are being fabricated.
- FIG. 5 is a cross-sectional view of a surface acoustic wave device according to
embodiment 4 of the present invention. - FIG. 6 is a cross-sectional view of a surface acoustic wave device according to
embodiment 5 of the present invention. - FIG. 7 is a plan view of a
chip 1 used by theembodiment 5 of the present invention. - FIG. 8 is a cross-sectional view of a surface acoustic wave device according to
embodiment 6 of the present invention. - FIGS. 9A to9F are schematic views showing steps to fabricate a chip for use by a surface acoustic wave device, the steps constituting a method according to
embodiment 7 of the present invention. - FIG. 10 is a cross-sectional view of a conventional surface acoustic wave device.
- FIG. 11 is a cross-sectional view of another conventional surface acoustic wave device disclosed in Japanese Patent Application Laid-open No. (Hei) 4-301910.
- Embodiments of the present invention will be described below with reference to the accompanying drawings. It is noted that the same reference symbols in the drawings denote the same or corresponding components.
-
Embodiment 1 - An
embodiment 1 of this invention will now be described with reference to FIG. 1. FIG. 1 is a cross-sectional view of a surface acoustic wave device according toembodiment 1. - In FIG. 1,
reference numeral 1 denotes a piezoelectric substrate chip constituting a surface acoustic wave element. On a principal plane of the chip 1 (upper surface in FIG. 1) are a surface acoustic wavefunctional portion 1 a and electrode pads. Thefunctional portion 1 a comprises driving electrodes made of known IDTs, and propagation paths for surface waves driven in a predetermined direction on the chip surface. The electrode pads, not shown, extend from the driving electrodes and serve as external connection terminals of thefunctional portion 1 a. -
Reference numeral 3 denotes a circuit substrate on which to mount the chip; 3 c for a terminal portion formed on a part of thecircuit substrate 3; 4 for wires that connect the electrode pads of thefunctional portion 1 a electrically to theterminal portion 3 c; 2 a for a frame-like first insulating film deposited on the upper surface of thechip 1 surrounding thefunctional portion 1 a on thechip 1; and 2 b for a lid-like second insulating film attached to the first insulatingfilm 2 a in covering relation therewith. The secondinsulating film 2 b ensures a suitablehollow portion 9 over thefunctional portion 1 a and protectively envelopes the driving electrodes and surface acoustic wave propagation paths of thefunctional portion 1 a. - In the surface acoustic wave device of the above constitution, the crucially important
functional portion 1 a is protected by the first and the secondinsulating film hollow portion 9 interposed therebetween. The makeup allows thechip 1 to be fabricated in a secure manner with little risk of getting thefunctional portion 1 a inadvertently damaged during the process. - Because the first and the second
insulating film functional portion 1 a in a simplified fashion, it is not mandatory, as with conventional surface acoustic wave devices, to provide costly airtight sealing on the functional portion. The result is an inexpensively manufactured surface acoustic wave device. - Embodiment 2
- An embodiment 2 of the invention will now be described with reference to FIG. 2. FIG. 2 is a cross-sectional view of a surface acoustic wave device according to embodiment 2. In FIG. 2, those parts with their counterparts already shown in FIG. 1 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive.
- In FIG. 2,
reference numeral 5 represents an insulating resin. Thechip 1, with itsfunctional portion 1 a capped by the first and the secondinsulating film circuit substrate 3.Metal wires 4 are used to connect thefunctional portion 1 a electrically to theterminal portion 3 c. The insulatingresin 5 is deposited so as to cover thechip 1 andmetal wires 4. This makeup ensures the same effects as theembodiment 1 and provides a surface acoustic wave device still more reliable than theembodiment 1. -
Embodiment 3 - An
embodiment 3 of this invention will now be described with reference to FIGS. 3A to 3F, and FIGS. 4A and 4B. FIGS. 3A to 3F are schematic views showing steps to fabricate a chip for use by a surface acoustic wave device according to theembodiment 3. FIGS. 4A and 4B are perspective views illustrating respectively typical states of the chips in FIGS. 3D and 3F as they are being fabricated. - FIG. 3A shows a
wafer 30. On thewafer 30, a plurality offunctional portions 1 a are formed through conductor patterning at suitable intervals as indicated in FIG. 3B. - A
photosensitive film 40 is then deposited on allfunctional portions 1 a on thewafer 30 as illustrated in FIG. 3C. With thefilm 40 in place, a frame-like firstinsulating film 2 a is formed by photolithography so as to surround each functional portion as shown in FIGS. 3D and 4A. FIG. 4A depicts a case in which twofunctional portions 1 a are surrounded by the first insulatingfilm 2 a. - Thereafter, a single
photosensitive film 50 is deposited on the first insulatingfilm 2 a over the wafer as illustrated in FIG. 3E. The process creates a suitablehollow portion 9 between eachfunctional part 1 a and thephotosensitive film 50. With the hollow portions thus provided, a lid-like secondinsulating film 2 b is formed also by photolithography (as in FIGS. 3D and 4A) to cover each of the first insulatingfilms 2 a as depicted in FIG. 3F and 4B. - After that, the wafer is diced up along
separation lines 60 separating chips as shown in FIGS. 4A and 4B, whereby the individual chips are formed. - As described, the
embodiment 3 of the invention has its first and second insulating films fabricated finely, precisely and efficiently, the films offering the same effects as those of the first and the embodiment 2. -
Embodiment 4 - An
embodiment 4 of this invention will now be described with reference to FIG. 5. FIG. 5 is a cross-sectional view of a surface acoustic wave device according toembodiment 4. In FIG. 5, those parts with their counterparts already shown in FIG. 1 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive. - In FIG. 5,
reference numeral 6 denotes bump electrodes constituting external connectors of thefunctional portion 1 a. Thechip 1, with itsfunctional portion 1 a capped by the first and the secondinsulating film bump electrodes 6 tosuitable connectors 3 c on thecircuit substrate 3 in flip-chip bonding fashion. - The makeup above allows the
embodiment 4 to be a smaller surface acoustic wave device than theembodiment 1 while offering the same effects as those of the latter. - If part or all of the chip is covered with an appropriate insulating resin as is the case with the embodiment 2, the
embodiment 4 may be fabricated as a surface acoustic wave device with significantly enhanced reliability. -
Embodiment 5 - An
embodiment 5 of this invention will now be described with reference to FIGS. 6 and 7. FIG. 6 is a cross-sectional view of a surface acoustic wave device according to theembodiment 5. FIG. 7 is a plan view of achip 1 used by theembodiment 5. - In FIGS. 6 and 7, those parts with their counterparts already shown in FIG. 1 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive.
- As shown in FIGS. 6 and 7, an insulating
film 7 is formed over thechip 1 except where there are at least thefunctional portion 1 a and theelectrode pads 10 constituting external connectors of thefunctional portion 1 a. The thickness of the insulatingfilm 7 should preferably be made equal to or slightly less than that of thebump electrodes 6 as depicted in FIG. 6. - The
chip 1 is mounted on thebump electrodes 6 so that ahollow portion 9 is secured over itsfunctional portion 1 a as shown in FIG. 6. Thechip 1 is then connected tosuitable connectors 3 c on thecircuit substrate 3 in flip-chip bonding fashion, with ananisotropic conductor 8 interposed between thebump electrodes 6 and theconnectors 3 c. - In the
embodiment 5 of the above constitution, thechip 1 is bonded to thecircuit substrate 3 not only via thebump electrodes 6 but also through the insulatingfilm 7. This setup prevents junction stress from getting concentrated locally, thereby implementing a surface acoustic wave device with itsbump electrodes 6 offering high connection reliability. - If part or all of the chip is covered with an appropriate insulating resin as is the case with the embodiment 2, the
embodiment 5 may also be fabricated as a surface acoustic wave device with significantly enhanced reliability. - Furthermore, if the insulating
film 7 is formed by photolithography using a photosensitive material as with theembodiment 3, theembodiment 5 will have its insulatingfilm 7 fabricated finely, precisely and efficiently. -
Embodiment 6 - An
embodiment 6 of this invention will now be described with reference to FIG. 8. FIG. 8 is a cross-sectional view of a surface acoustic wave device according toembodiment 6. In FIG. 8, those parts with their counterparts already shown in FIG. 1 are given the same reference numerals, and descriptions of such parts are omitted where they are repetitive. - As shown in FIG. 8, a first
insulating film 7 a is formed over thechip 1 except where there are at least thefunctional portion 1 a andbump electrode pads 10. A secondinsulating film 7 b is deposited on the first insulatingfilm 7 a. Thefunctional portion 1 a of thechip 1 is covered with the first and the secondinsulating film hollow portion 9 is secured over the surface of thefunctional part 1 a. Those parts of thefilms electrode pads 10 are removed so that thebump electrodes 6 are exposed. The combined thickness of the first and the secondinsulating film bump electrodes 6. - The
chip 1 is connected by thebump electrodes 6 tosuitable connectors 3 c on thecircuit substrate 3 in flip-chip bonding fashion, with theanisotropic conductor 8 interposed between thebump electrodes 6 and theconnectors 3 c. - The
embodiment 6 of the above constitution provides the same effects as theembodiment 5. Because the crucially importantfunctional portion 1 a is protected by the first and the secondinsulating film chip 1 to be fabricated in a secure manner with little risk of getting thefunctional portion 1 a inadvertently damaged during the process. - Because the first and the second
insulating film functional portion 1 a in a simplified fashion, it is not mandatory, as with conventional surface acoustic wave devices, to provide costly airtight sealing on the functional portion. This makes it possible to manufacture an inexpensive yet viable surface acoustic wave device. - If part or all of the chip is covered with an appropriate insulating resin as is the case with the embodiment 2, the
embodiment 6 may also be fabricated as a surface acoustic wave device with significantly enhanced reliability. - Furthermore, if the first and the second
insulating film embodiment 3, theembodiment 6 will have its first and second insulatingfilms -
Embodiment 7 - An
embodiment 7 of this invention will now be described with reference to FIGS. 9A to 9F. FIGS. 9A to 9F are schematic views showing steps to fabricate a chip for use by a surface acoustic wave device, the steps constituting a method according toembodiment 7. - FIG. 9A shows a
wafer 30. On thewafer 30, a plurality offunctional portions 1 a are formed through conductor patterning at suitable intervals as depicted in FIG. 9B. - A first insulating
film 7 a made illustratively of a photosensitive material is then deposited on the wafer surface comprising thefunctional portions 1 a. The firstinsulating film 7 a is shaped as shown in FIG. 9C by photolithography, with thefunctional portions 1 a and electrode pads for bump electrodes excluded. - In the state above, a second
insulating film 7 b composed of a photosensitive material is further deposited on the first insulatingfilm 7 a. A lid covering thefunctional portions 1 a is formed by similar photolithography. With the electrode pads for bump electrodes excluded, the secondinsulating film 7 b is then formed as shown in FIG. 9C. - The
bump electrodes 6 corresponding to each of the functional portions are furnished as illustrated in FIG. 9D. At this point, the combined thickness of the first and the secondinsulating film bump electrodes 6. - Thereafter, as shown in FIG. 9E, a single
anisotropic conductor 8 is furnished so as to cover all functional portions and theirbump electrodes 6, the conductor being in contact with the bump electrodes. - In this state, the wafer is diced up along
separation lines 60 separating chips as shown in FIG. 9F, whereby the individual chips are formed. - By use of the above method according to
embodiment 7, it is possible to fabricate efficiently a surface acoustic wave device offering the same effects as those of the fifth and theembodiment 6. - The surface acoustic wave device of the present invention has surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on a principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, a frame-like first insulating film furnished on the principal plane of the piezoelectric substrate so as to surround the functional portion and a lid-like second insulating film for covering the driving electrodes and surface wave propagation paths of the functional portion while securing a predetermined space over the functional portion. This structure provides a hollow portion over the surface of the functional portions so that the device is fabricated in secure, damage-free fashion.
- In the surface acoustic wave device of the present invention, the surfaces of the surface acoustic wave elements may be covered with an insulating resin. This makes it possible to fabricate a more reliable surface acoustic wave device than before.
- The surface acoustic wave device of the present invention may further comprise bump electrodes which are formed on either one principal plane or another principal plane of the piezoelectric substrate and which constitute external connectors of the surface acoustic wave elements, wherein the surface acoustic wave elements are connected via the bump elements to the circuit substrate in flip-chip bonding fashion. This preferred structure helps reduce the size of the surface acoustic wave device.
- The surface acoustic wave device of the present invention has surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on a principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, bump electrodes which are formed on the principal plane of the piezoelectric substrate and which constitute external connectors of the functional portion and an insulating film deposited on the principal plane of the piezoelectric substrate except where there exist at least the functional portion and the bump electrodes, wherein the surface acoustic wave elements are connected via the bump electrodes to the circuit substrate in flip-chip bonding fashion, with an anisotropic conductor interposed between the bump electrodes and the circuit substrate. This structure prevents junction stress from getting concentrated locally on the chip, allowing the bump electrodes to offer high connection reliability.
- The surface acoustic wave device of the present invention has surface acoustic wave elements mounted on a circuit substrate, each of the surface acoustic wave elements comprises a piezoelectric substrate, a functional portion which is formed on a principal plane of the piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, a first insulating film deposited on the principal plane of the piezoelectric substrate except where there exist at least the functional portion and bump electrodes and a second insulating film deposited on the first insulating film so as to secure a predetermined space over the functional portion while covering the driving electrodes and surface wave propagation paths of the functional portion except where there exist at least the bump electrodes, wherein the surface acoustic wave elements are connected via the bump electrodes to the circuit substrate in flip-chip bonding fashion, with an anisotropic conductor interposed between the bump electrodes and the circuit substrate. This structure reinforces protection of the functional portions and eliminates the need for providing their airtight sealing. The resulting device is inexpensive and, with junction stress dispersed over the chip, fabricated in a way that allows its bump electrodes to offer high connection reliability.
- In the surface acoustic wave device of the present invention, the first and the second insulating film of the surface acoustic wave device may be composed of photosensitive films and formed by photolithography. This structure allows the insulating films to be fabricated finely, precisely and efficiently.
- A method for fabricating a surface acoustic wave device of the present invention comprises the steps of forming functional portions of a plurality of surface acoustic wave elements on one principal plane of a piezoelectric substrate, the function portions including driving electrodes for driving surface waves in a predetermined direction over a surface of the piezoelectric substrate, depositing a first insulating film on the principal plane of the piezoelectric substrate except where there exist at least the functional portions and electrode pads for use by bump electrodes, depositing on the first insulating film a second insulating film in lid fashion covering each of the functional portions except each of the electrode pads so as to secure a predetermined space over the functional portions while covering the driving electrodes and surface wave propagation paths of the functional portions, furnishing each of the functional portions with the bump electrodes constituting external connectors of the functional portions on the principal plane of the piezoelectric substrate, providing a single anisotropic conductor so as to cover the plurality of functional portions and each of the bump electrodes, connecting the bump electrodes to the circuit substrate in flip-chip bonding fashion and separating the surface acoustic wave elements into individual elements. This method fabricates the inventive surface acoustic wave device efficiently.
- Preferably, the inventive method may further comprise the steps of having the first and the second insulating film composed of photosensitive films and formed by photolithography. The additional steps make it possible to fabricate the insulating films finely, precisely and efficiently.
- The present invention has been described in detail with respect to various embodiments, and it will now be apparent from the foregoing to those skilled in the art that changes and modifications may be made without departing from the invention in its broader aspects, and it is the invention, therefore, in the appended claims to cover all such changes and modifications as fall within the true spirit of the invention.
- The entire disclosure of Japanese Patent Application No. 10-282814 filed on Oct. 5, 1998 including specification, claims, drawings and summary are incorporated herein by reference in its entirety.
Claims (8)
1. A surface acoustic wave device having surface acoustic wave elements mounted on a circuit substrate, each of said surface acoustic wave elements comprising:
a piezoelectric substrate;
a functional portion which is formed on one principal plane of said piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of said piezoelectric substrate;
a frame-like first insulating film furnished on the one principal plane of said piezoelectric substrate so as to surround said functional portion; and
a lid-like second insulating film for covering the driving electrodes and surface wave propagation paths of said functional portion while securing a predetermined space over said functional portion.
2. The surface acoustic wave device according to , wherein surfaces of said surface acoustic wave elements are covered with an insulating resin.
claim 1
3. A surface acoustic wave device according to , further comprising bump electrodes which are formed on either the one principal plane or other principal plane of said piezoelectric substrate and which constitute external connectors of said surface acoustic wave elements, wherein said surface acoustic wave elements are connected via said bump elements to said circuit substrate in flip-chip bonding fashion.
claim 1
4. A surface acoustic wave device having surface acoustic wave elements mounted on a circuit substrate, each of said surface acoustic wave elements comprising:
a piezoelectric substrate;
a functional portion which is formed on one principal plane of said piezoelectric substrate and which has driving electrodes for driving surface waves in a predetermined direction over a surface of said piezoelectric substrate;
bump electrodes which are formed on the one principal plane of said piezoelectric substrate and which constitute external connectors of said functional portion; and
an first insulating film deposited on the one principal plane of said piezoelectric substrate except where there exist at least said functional portion and said bump electrodes;
wherein said bump electrodes of said surface acoustic wave elements are connected to said circuit substrate in flip-chip bonding fashion, with an anisotropic conductor interposed between said bump electrodes and said circuit substrate.
5. The surface acoustic wave device according to , further comprising a second insulating film deposited on said first insulating film so as to secure a predetermined space over said functional portion while covering the driving electrodes and surface wave propagation paths of said functional portion except where there exist at least said bump electrodes.
claim 4
6. The surface acoustic wave device according to , wherein said first and said second insulating film are composed of photosensitive films and are formed by photolithography.
claim 1
7. A method for fabricating a surface acoustic wave device, said method comprising the steps of:
forming functional portions of a plurality of surface acoustic wave elements on one principal plane of a piezoelectric substrate, said function portions including driving electrodes for driving surface waves in a predetermined direction over a surface of said piezoelectric substrate;
depositing a first insulating film on the one principal plane of said piezoelectric substrate except where there exist at least said functional portions and electrode pads for use by bump electrodes;
depositing a second insulating film in lid fashion over said functional portions except where there exist at least said electrode pads on said first insulating film so as to secure a predetermined space while covering said driving electrodes and surface wave propagation paths of said functional portions;
furnishing each of said functional portions with said bump electrodes constituting external connectors of said functional portions on the one principal plane of said piezoelectric substrate;
providing a single anisotropic conductor so as to cover the plurality of said functional portions and each of said bump electrodes;
connecting said bump electrodes to said circuit substrate in flip-chip bonding fashion; and
separating said surface acoustic wave elements into individual elements.
8. The method for fabricating a surface acoustic wave device according to , wherein said first and said second insulating film are composed of photosensitive films and are formed by photolithography.
claim 7
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
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JP10-282814 | 1998-10-05 | ||
JP10282814A JP2000114918A (en) | 1998-10-05 | 1998-10-05 | Surface acoustic wave device and its manufacture |
JPHEI10-282814 | 1998-10-05 |
Publications (2)
Publication Number | Publication Date |
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US20010011857A1 true US20010011857A1 (en) | 2001-08-09 |
US6310421B2 US6310421B2 (en) | 2001-10-30 |
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US09/231,836 Expired - Fee Related US6310421B2 (en) | 1998-10-05 | 1999-01-15 | Surface acoustic wave device and method for fabricating the same |
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US (1) | US6310421B2 (en) |
JP (1) | JP2000114918A (en) |
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US9543268B2 (en) | 2011-07-25 | 2017-01-10 | Murata Manufacturing Co., Ltd. | Electronic component, method of manufacturing same, composite module including electronic component, and method of manufacturing same |
US20160156333A1 (en) * | 2014-12-02 | 2016-06-02 | Samsung Electro-Mechanics Co., Ltd. | Printed circuit board and method of manufacturing the same |
KR20160066338A (en) * | 2014-12-02 | 2016-06-10 | 삼성전기주식회사 | Printed circuit board and manufacturing method thereof |
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US6310421B2 (en) | 2001-10-30 |
JP2000114918A (en) | 2000-04-21 |
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