JP2010034782A - Elastic boundary wave device, manufacturing method thereof, and manufacturing method of duplexer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce cost by reducing the number of processes of manufacturing a duplexer and a module-use elastic boundary wave device. <P>SOLUTION: A wafer-forming a filter is made into individual pieces, these pieces are mounted on a circuit substrate having a phase matching circuit, and forms a clad layer 14, thereby enabling a patterning process of the clad layer 14 to be reduced. Namely, although in a prior art manufacturing method of an elastic boundary wave device, patterning which does not cover an electrode with the clad layer is required, when the clad layer is formed, since such a clad layer patterning is not required in this embodiment, the number of processes at the time of manufacturing can be reduced, and this leads to reduction in the manufacturing cost. Accordingly, an elastic boundary wave device can be manufactured at low cost. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a boundary acoustic wave device and a manufacturing method thereof. The present invention also relates to a method of manufacturing a duplexer including a boundary acoustic wave device.

  A surface acoustic wave (SAW) device has been well known as one of devices using an elastic wave. This SAW device is, for example, various circuits for processing a radio signal in a frequency band of 45 MHz to 2 GHz typified by a cellular phone, such as a transmission band pass filter, a reception band pass filter, a local oscillation filter, an antenna duplexer, an IF filter, an FM Used for modulators and the like.

  A problem with an acoustic wave device is temperature characteristics that vary with temperature. In order to improve temperature characteristics, Patent Document 1 discloses a surface acoustic wave device in which a silicon oxide film having a temperature characteristic different from that of a piezoelectric substrate is formed on a piezoelectric substrate.

  In order to realize improvement in temperature characteristics and miniaturization of elements, an elastic wave device using a Love wave and an elastic boundary wave device using a boundary wave propagating through a boundary between different media are disclosed in Patent Document 2, Patent Document 3, and Non-Patent Document 3. It is disclosed in Patent Document 1.

FIG. 2A is a plan view of an elastic wave device using a Love wave disclosed in Patent Document 2. FIG. 2B is a cross-sectional view taken along the line ZZ in FIG. 2A. As shown in FIGS. 2A and 2B, in the conventional acoustic wave device, a series resonator 302 and a parallel resonator 303 formed of electrodes are formed on a piezoelectric substrate 301. The series resonator 302 and the parallel resonator 303 are covered with a dielectric film 310 made of, for example, SiO ₂ . The electrodes are comb-shaped electrodes 302a and 303a that excite elastic waves, reflectors 302b and 303b that reflect elastic waves, and terminal portions (input / output electrodes 304) that are connected to the comb-shaped electrodes 302a to form Au bumps. 305, ground electrodes 306 and 307, and a dummy electrode 308). The comb-shaped electrodes 302 a and 303 a and the reflectors 302 b and 303 b are covered with the dielectric film 310, but the terminal portions are not covered with the dielectric film 310. The dielectric film 310 is thicker than the electrode, and is approximately (0.3 × λ) when the wavelength of the surface acoustic wave is λ.

  3A to 3E are plan views showing a manufacturing process of the acoustic wave device shown in FIGS. 2A and 2B. When manufacturing the acoustic wave device shown in FIGS. 2A and 2B, first, as shown in FIG. 3A, the series resonator 302 and the parallel resonator 303 are formed on the piezoelectric substrate 301. Next, as shown in FIG. 3B, a connection electrode 309 that electrically connects the series resonator 302 and the parallel resonator 303 is formed. 3A and 3B may be performed simultaneously. Next, as shown in FIG. 3C, input / output electrodes 304 and 305 and ground electrodes 306 and 307 are formed at the end of the connection electrode 309. A dummy electrode 308 is also formed. Next, as illustrated in FIG. 3D, the series resonator 302 and the parallel resonator 303 are covered with a dielectric film 310. Next, as shown in FIG. 3E, the piezoelectric substrate 301 is covered with an alumina film 311. At this time, the alumina film 311 is formed by patterning using a photolithography method or the like so that the input / output electrodes 304 and 305, the ground electrodes 306 and 307, and the dummy electrode 308 are exposed. However, in general, as disclosed in Patent Documents 4 and 5 and the like, in the boundary wave device, there is a wave excited as an unnecessary response other than the boundary wave at the boundary between two different media. Therefore, it is necessary to form a scattering layer that scatters an unnecessary response on the surface layer and a sound absorbing layer that absorbs sound based on the unnecessary response. In addition, although the piezoelectric substrate 301 shown to FIG. 3A-FIG. 3E is separated into pieces in illustration, it is actually a part of wafer. Therefore, although not shown, there is a step of dividing the piezoelectric substrate into pieces after the step shown in FIG. 3E.

  4A is a plan view of the boundary acoustic wave device described in Patent Document 3. FIG. 4B is a cross-sectional view of the YY portion in FIG. 4A. The boundary acoustic wave device shown in FIGS. 4A and 4B is an example in which the electrode 102 is formed on the piezoelectric substrate 104 and the second medium 106 and the third medium 107 that are dielectric films are formed on the electrode 102. is there. The electrode 102 includes a comb-shaped electrode 102a that excites an elastic wave, a reflector 102b that reflects the elastic wave, and a terminal portion 102c that is connected to the comb-shaped electrode 102a and on which an Au bump is formed. The comb-teeth electrode 102a and the reflector 102b are covered with the second medium 106 and the third medium 107, but the terminal part 102c on which the Au bump is formed is the second medium 106 and the third medium. 107 is not covered.

In the configuration shown in FIGS. 4A and 4B, the dielectric layer (second medium 106 and third medium 107) is formed of two layers, but the elasticity of the Love wave structure shown in FIGS. 5A and 5B. those as thick SiO ₂ parts in the boundary wave device has also been reported (non-Patent Document 2).

The devices disclosed in Patent Documents 1 to 3 and Non-Patent Documents 1 and 2 are expected to have high reliability because the electrode surface is covered with a thick film.
JP 2003-209458 A JP 2004-112748 A JP-A-10-549008 International Publication No. 2004/095699 Pamphlet JP 2007-243473 A Masatsune Yamaguchi, Takashi Yamashita, Ken-ya Hashimoto, Tatsuya Omori, “Highly Piezoelectric Boundary Waves in Si / SiO2 / LiNbO3 Structure”, Proceeding of 1998 IEEE International Frequency Control Symposium, (USA), IEEE, 1998, p484-488 Hajime Kando et al., 2006 IEEE International Ultrasonics Symposium 6B-4 'RF Filter using Boundary Acoustic Wave'

  Conventional boundary acoustic wave devices have advantages such as good temperature characteristics, high reliability, and no need to form a hollow space, as compared to SAW devices. However, the boundary acoustic wave device has more layers than the SAW device, which increases the number of manufacturing steps, leading to an increase in manufacturing cost.

  Further, when a duplexer or a module is configured with a boundary acoustic wave device, it is not very advantageous that a hollow space need not be formed. For example, when configuring a duplexer, two filters, a transmission filter and a reception filter, and a phase matching circuit are required. Therefore, the filter is connected to the substrate on which the phase matching circuit is formed. At that time, in the recent downsized duplexer, the filter is connected to the substrate by flip chip bonding. As a result, since the electrode connection portion is naturally formed as a hollow space, it is not advantageous that the hollow space is not required.

  Therefore, the boundary acoustic wave filter is more expensive than the SAW device in applications other than the single filter.

  An object of the present invention is to reduce costs by reducing the number of manufacturing steps of boundary acoustic wave devices for duplexers and modules.

  The method for manufacturing a boundary acoustic wave device according to the present invention includes a step of forming an electrode and a first insulating layer on a wafer surface which is a first medium layer, a step of forming a bump on a terminal portion of the electrode, Separating the first medium layer into chips, connecting the chip to a wiring board with a flip chip, and applying an insulating material on the wiring board to which the chip is connected. Forming a second insulating layer so as to cover the insulating layer.

  The duplexer manufacturing method of the present invention includes a step of forming an electrode and a first insulating layer on a wafer surface which is a first medium layer, a step of forming a gold bump on a terminal portion of the electrode, A step of dividing the medium layer into chips, a step of connecting at least two of the chips to the wiring substrate on which the phase matching circuit is formed, and an insulating material on the wiring substrate to which the chips are connected And a step of forming a second insulating layer on the first insulating layer by applying and baking, and molding the wiring substrate to which the chip is connected with a resin, in the gap between the chip and the wiring substrate. The method includes a step of filling a resin and a step of dividing the wiring board into individual pieces.

  A boundary acoustic wave device according to the present invention includes a chip having a first medium layer, an electrode and a first insulating layer formed on the first medium layer, and a bump formed on a terminal portion of the electrode. And a wiring substrate to which the chip is connected by flip-chip mounting, and a second substrate mainly composed of an inorganic material formed on the surface of the wiring substrate and the chip so as to cover the first insulating layer. And an insulating layer.

  According to the present invention, it is possible to reduce the number of manufacturing steps of boundary acoustic wave devices for duplexers and modules. Therefore, it is possible to reduce the manufacturing costs of boundary acoustic wave devices and duplexers and modules including the boundary acoustic wave devices.

  The boundary acoustic wave device manufacturing method of the present invention can take the following aspects based on the above method.

  That is, the boundary acoustic wave device manufacturing method of the present invention may further include a step of molding the wiring substrate to which the chip is connected with a resin, and filling the gap between the chip and the wiring substrate with the resin. it can.

  The boundary acoustic wave device manufacturing method of the present invention may further include a step of separating the wiring substrate to which the chip is connected.

  The method for manufacturing a boundary acoustic wave device according to the present invention may further include a step of immersing the wiring board to which the chip is connected in a liquid insulating material.

  In the boundary acoustic wave device manufacturing method of the present invention, the insulating material may be composed of a liquid inorganic material containing alumina.

  In the method for manufacturing a boundary acoustic wave device of the present invention, the insulating material may be composed of a sol whose main component is a metal alkoxide containing aluminum.

(Embodiment)
1A to 1H are plan views showing a method for manufacturing a boundary acoustic wave device according to the present embodiment. The piezoelectric substrate 1 shown in FIGS. 1A to 1D is separated into pieces in the drawing, but actually has a configuration in which a plurality of the piezoelectric substrates shown in the drawing are arranged on a wafer.

  First, as shown in FIG. 1A, a series resonator 2a and a parallel resonator 2b are formed on a piezoelectric substrate 1 (first medium layer).

  Next, as shown in FIG. 1B, a connection electrode 3 that electrically connects the series resonator 2a and the parallel resonator 2b is formed. 1A and 1B may be performed simultaneously.

  Next, as shown in FIG. 1C, input / output electrodes 4 a and 4 b and ground electrodes 4 c and 4 d are formed at the end of the connection electrode 3. A dummy electrode 4e is also formed. Next, as shown in FIG. 1D, the series resonator 2 a and the parallel resonator 2 b are covered with a dielectric film 5.

  Next, as shown in FIG. 1D, Au bumps are formed on the input / output electrodes 4a and 4b, the ground electrodes 4c and 4d, and the dummy electrode 4e (both see FIG. 1C).

  Next, as shown in FIG. 1E, the wafer is separated into pieces by a dicing process to produce a chip. Specifically, the substrate 22 arranged on the wafer ring 21 is cut at a broken line portion in the drawing. A plurality of piezoelectric substrates 10 on which electrodes and the like are formed are arranged on the substrate 22 after cutting as shown in FIG. 1D, and the boundary portion of each piezoelectric substrate 1 corresponds to a broken line.

  Next, as shown in FIG. 1F, the separated piezoelectric substrate 10 is flip-chip mounted on the wiring substrate 11. Specifically, the Au bumps 12 disposed on the back surface of the piezoelectric substrate 10 are electrically connected to a predetermined pattern on the wiring substrate 11. FIG. 1F (a) is a plan view of the wiring board 11 on which a chip is mounted. FIG. 1F (b) is a cross-sectional view of the ZZ portion in FIG. 1F (a). Moreover, the wiring board 11 is a wiring board of a duplexer shown in FIG. 6, for example. By mounting the chip on the wiring substrate 11 on which the phase matching circuit 53 is formed in advance, the transmission filter 53, the reception filter 54, and the like can be formed. Thereby, the duplexer shown in FIG. 6 is formed on the wiring board 11.

  Next, as shown in FIG. 1G, a liquid insulating material is applied to the wiring substrate 11 on which the chip is mounted. In this embodiment, a method of immersing in a liquid insulating material after the terminal portion of the wiring board 11 is protected with a tape or the like is employed in the present embodiment. In this embodiment, the insulating material is applied to the wiring substrate 11 by immersion in the insulating material. However, the spin coating method in which the insulating material is dropped and coated by rotating the wiring substrate 11, etc. It may be applied by other methods. In the present embodiment, Aron ceramic D containing minute alumina is used as the insulating material, but a liquid inorganic material can be used. In addition to the material of the present embodiment, the insulating material may be any material that forms alumina by firing, and for example, a metal alkoxide sol containing alumina can be used.

  Next, as shown in FIG. 1H, after applying an insulating material to the wiring substrate 11 on which the chip is mounted, the substrate is left at room temperature for 24 hours and heated at 90 ° C. for 1 hour. Further, the insulating material is cured by heating at 150 ° C. for 1 hour or longer to form the cladding layer 14. Further, in order to protect the surface, a resin is dropped and filled on the surface of the clad layer 14 and heated at 150 ° C. to be cured. As a resin for protecting the surface of the clad layer 14, an epoxy resin generally used as a sealing material was used.

  Next, the wiring board 11 is diced into individual pieces. Thereby, the duplexer in which the boundary acoustic wave device is mounted is completed.

  When the boundary acoustic wave device manufactured by the above manufacturing method was evaluated, resonance characteristics derived from the boundary wave could be obtained.

  Although this embodiment is an example in which one resonator is mounted on a wiring board, a duplexer is formed by mounting a plurality of filters (chips) and mounting a phase matching circuit on the circuit board. be able to.

  According to the present embodiment, the wafer on which the filter is formed is singulated (step of FIG. 1E) and mounted on a circuit board having a phase matching circuit (step of FIG. 1F) to form the clad layer 14 (FIG. 1). 1H), the patterning process of the cladding layer 14 can be reduced. That is, in the conventional boundary acoustic wave device manufacturing method shown in FIGS. 3A to 3E, when the cladding layer is formed with the third medium 311 as shown in FIG. 3E, the input / output electrodes 304 and 305, the ground electrode 306 and 307, the dummy electrode 308 needs to be patterned so as not to be covered with the third medium 311, but in this embodiment, such patterning of the clad layer is not necessary, so that the manufacturing process can be reduced. Manufacturing costs can be reduced. Therefore, the boundary acoustic wave device can be manufactured at a lower cost.

  In the present embodiment, the method of mounting the boundary acoustic wave device on the duplexer has been described. However, the present invention can also be applied to a method of mounting the boundary acoustic wave device on a communication module or the like.

The top view which shows the state in which the resonator was formed in the board | substrate in the manufacturing method of the boundary acoustic wave device of this Embodiment The top view which shows the state in which the connection electrode was formed in the board | substrate in the manufacturing method of the boundary acoustic wave device of this Embodiment The top view which shows the state in which the terminal electrode was formed in the connection electrode in the manufacturing method of the boundary acoustic wave device of this Embodiment The top view which shows the state in which the 2nd medium was formed in the resonator in the manufacturing method of the boundary acoustic wave device of this Embodiment The perspective view which shows the structure of the wafer in the manufacturing method of the boundary acoustic wave device of this Embodiment. (A) In the manufacturing method of the boundary acoustic wave device of this embodiment, the top view which shows the state by which the board | substrate separated into pieces was connected to the wiring board, (b) XX part of the figure (a). Cross section Sectional drawing which shows the state which covered the wiring board with the insulating film in the manufacturing method of the boundary acoustic wave device of this Embodiment Sectional drawing which shows the state in which the cladding layer was formed in the manufacturing method of the boundary acoustic wave device of this Embodiment Plan view showing the configuration of a boundary acoustic wave device Sectional drawing of the ZZ part in FIG. 2A AE is a top view which shows the manufacturing method of the conventional boundary acoustic wave device. The top view which shows the structure of the boundary acoustic wave device disclosed by patent document 3 Sectional drawing of the YY part in FIG. 4A The top view which shows the structure of the elastic wave device of patent document 2 Sectional drawing of the YY part in FIG. 5A Block diagram showing the configuration of the duplexer

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric substrate 2a Series resonator 2b Parallel resonator 3 Connection electrode 4a, 4b Input / output electrode 4c, 4d Ground electrode 5 Dielectric film

Claims (8)

Forming an electrode and a first insulating layer on a wafer surface that is a first medium layer;
Forming bumps on the terminal portions of the electrodes;
Separating the first medium layer into chips, and
Connecting the chip to the wiring board by flip chip;
Forming a second insulating layer so as to cover the first insulating layer by applying an insulating material on the wiring substrate to which the chip is connected.   The method for manufacturing a boundary acoustic wave device according to claim 1, further comprising: molding the wiring substrate to which the chip is connected with a resin, and filling the gap between the chip and the wiring substrate with the resin.   The method for manufacturing a boundary acoustic wave device according to claim 1, further comprising a step of separating the wiring substrate to which the chip is connected.   The method for manufacturing a boundary acoustic wave device according to claim 1, further comprising a step of immersing the wiring board to which the chip is connected in a liquid insulating material.   The method for manufacturing a boundary acoustic wave device according to claim 1, wherein the insulating material is made of a liquid inorganic material containing alumina.   The method for manufacturing a boundary acoustic wave device according to claim 1, wherein the insulating material is made of a sol whose main component is a metal alkoxide containing aluminum. Forming an electrode and a first insulating layer on a wafer surface that is a first medium layer;
Forming gold bumps on the terminal portions of the electrodes;
Separating the first medium layer into chips, and
Connecting at least two chips by flip chip to a wiring board on which a phase matching circuit is formed;
Forming a second insulating layer on the first insulating layer by applying and baking an insulating material on the wiring substrate to which the chip is connected; and
Molding the wiring board to which the chip is connected with a resin, and filling the resin between the chip and the wiring board;
A duplexer manufacturing method comprising: a step of separating the wiring board into pieces. A chip having a first medium layer, an electrode and a first insulating layer formed on the first medium layer, and a bump formed on a terminal portion of the electrode;
A wiring board to which the chip is connected by flip chip mounting;
A boundary acoustic wave device comprising: a second insulating layer mainly composed of an inorganic material, which is formed so as to cover the first insulating layer on a surface of the wiring board and the chip.

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