JP2003115734A - Surface acoustic wave device and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that a piezoelectric single crystal material such as tantalic acid lithium or niobic acid lithium is difficult to make thin because it is easily broken and this prevents a device from being reduced in height. SOLUTION: On a principal plane of a piezoelectric substrate finished into a mirror face, comb-shaped electrodes and pad electrodes are provided, a space forming portion is provided so as to cover the comb-shaped electrodes, and protruding electrodes are provided on the pad electrodes. An insulating material is provided so as to cover the protruding electrodes and the space forming portion, the protruding electrodes are exposed from the material by grinding the material, and terminal electrodes are provided so as to cross the protruding electrodes. The other principal plane of the substrate is ground or polished to thin the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a surface acoustic wave device used as a frequency filter or a resonator mounted in communication equipment such as a mobile phone and a keyless entry.

[0002]

2. Description of the Related Art In recent years, the size and weight of communication devices typified by mobile phones have been rapidly reduced, and the surface area of surface acoustic wave devices such as filters and resonators mounted on the devices has been reduced. There is a demand for miniaturization (reduction of area) and reduction of device height (reduction of height).

FIG. 21 shows a conventional surface acoustic wave device which is most frequently used at present. In FIG. 21, a comb-shaped electrode 9 for exciting a surface acoustic wave is formed on a piezoelectric substrate 901.
02 is provided. As a material for the piezoelectric substrate, a piezoelectric single crystal such as lithium tantalate or lithium niobate is often used. Further, an electrode pad 903 for transmitting an electric signal is provided on the comb-shaped electrode. Piezoelectric substrate 9
01 is die-bonded to the package, and a resin is usually used for the die-bonding.

The electrode pads 903 are individually connected to the electrode pads 905 provided on the package by wires 904. The wire 904 is usually made of gold, aluminum or the like. Here, the package is composed of a laminated body of ceramics 910, 909, and 908 such as alumina, and is electrically connected to the terminal electrode 907 from the electrode pad 905 through the internal electrode 906. Although not shown, the piezoelectric substrate 901 is adhered to the ceramic substrate 908 with a resin adhesive material such as silicone. Also,
Reference numeral 911 is a lid made of ceramic or metal.

FIG. 22 shows a conventional device which can be made smaller than the device of FIG. Here, the piezoelectric substrate 90
1. A surface acoustic wave element including a comb electrode 902 and an electrode pad 903 is mounted face down. The connection with the substrate is made with conductive bumps 914, and a resin 913 is poured to strengthen the fixing of the surface acoustic wave element and the substrate 912.

[0006]

However, as shown in FIG.
In the conventional structure shown by, it is necessary to wire the wire 904 in the lateral direction and the height direction, and in order to hit the wire, the area of the electrode pads 903 and 905 must be increased, which makes the device compact. Is greatly hindered. Further, as the frequency of the device becomes higher, the parasitic inductance of the wire 904 may cause deterioration of the characteristics. Also, in the manufacturing process, the wires 904 have to be struck one by one on the corresponding electrode pads, which has been a factor that impedes cost reduction.

In the conventional example of FIG. 22, the size and cost can be reduced as compared with the conventional example of FIG. 21, but the thickness reduction of the substrate 912 and the piezoelectric substrate 901 is hindered. The thickness of the substrate 912 is usually about 0.2 to 0.3 mm, and the thickness of the piezoelectric substrate 901 is usually about 350 μm to 400 μm. Therefore, the height of the device is limited to about 600 μm.

The reason why the piezoelectric substrate is about 350 μm to 400 μm is that first, as the piezoelectric substrate 901, a piezoelectric single crystal material such as lithium tantalate, lithium niobate, or quartz, which is easily broken, is used. These materials have a strong resistance, and if the thickness is reduced, the wafer is damaged in the step of forming the comb-shaped electrodes and the like, so that the yield of the device is sharply deteriorated. Secondly, it is necessary that the surface (hereinafter referred to as the front surface) of the piezoelectric substrate on which the comb-shaped electrodes are formed be mirror-finished and the opposite surface (hereinafter referred to as the rear surface) be roughened.

Since the surface acoustic wave is a wave propagating in the vicinity of the surface of the substrate, the performance of the device is naturally influenced by the state of the surface of the substrate, and the surface acoustic wave propagating portion needs to be mirror-finished. Normally, at least the substrate surface roughness Ra is 10 nm, although it depends on the type and frequency of the surface acoustic wave.
Hereafter, it is necessary to finish to preferably 1 nm or less.
In addition, the back surface needs to be rough so that reflected waves from the back surface need to be scattered so as not to deteriorate the performance of the device. Therefore, at least the substrate surface roughness Ra is usually 0.1 μm or more. There is a need to.

In order to realize this aspect, # 8 is usually used.
Lapping is performed with abrasive grains of about 00 to # 1200. In this way, if the roughness on the front surface and the back surface is changed, the rough surface side becomes convex and the substrate warps. In a high frequency filter, the electrode pitch of the comb-shaped electrodes is on the order of submicrons, and a very precise photolithography technique is used. Therefore, if the substrate is warped, the device cannot be manufactured, or the manufacturing yield is extremely lowered. When the substrate is made thin, the amount of warpage increases, and such a problem becomes a problem. Therefore, it is difficult to make the substrate 0.35 μm or less.

In view of the above problems, it is an object of the present invention to provide a structure of a surface acoustic wave device which realizes downsizing of the device, in particular, reduction in height, and further cost reduction, and a manufacturing method thereof. It is what

[0012]

The polishing as referred to in the present invention means
This refers to a processing method in which an object is mechanically removed using a slurry in which abrasive grains such as alumina and silicon carbide are mixed in a liquid such as water, and wrapping corresponds to this. Polishing, which is a processing method for finishing the surface of a substrate into a mirror surface by using colloidal silica or the like, is also included in polishing in a broad sense, but in the present invention, the expression "mirror surface finish" is used to distinguish between them. Grinding in the present invention refers to a processing method in which an object is mechanically removed using a grindstone in which abrasive grains such as diamond are fixed by resin, ceramic, metal or the like. Further, the abrasive grains in grinding are usually called fixed abrasive grains.

According to the first aspect of the present invention, a step of providing a comb-shaped electrode for exciting a surface acoustic wave and a pad electrode electrically connected to the comb-shaped electrode on one main surface of the piezoelectric substrate. A step of providing a space forming portion provided so as to surround at least the comb-shaped electrode, a step of providing a protruding electrode on the pad electrode, and a main surface side of the piezoelectric substrate being fixed to a pedestal, And a step of grinding or polishing the other main surface of the substrate to thin the piezoelectric substrate, which is a method of manufacturing a surface acoustic wave device.

According to a second aspect of the present invention, a step of polishing both surfaces of the piezoelectric substrate to give a mirror finish, a comb-shaped electrode for exciting a surface acoustic wave on one main surface of the piezoelectric substrate, and the comb-shaped electrode are provided. A step of providing a pad electrode electrically connected, a step of providing a space forming portion provided so as to surround at least a part of the comb-shaped electrode, a step of providing a protruding electrode on the pad electrode, A step of fixing the main surface side of the piezoelectric substrate to a pedestal, grinding or polishing the other main surface of the piezoelectric substrate, and thinning the piezoelectric substrate. Is the way.

According to a third aspect of the present invention, there is provided a step of providing an insulating portion on the main surface side of the piezoelectric substrate so as to cover the space forming portion, and a terminal electrode electrically connected to the protruding electrode. 3. The method of manufacturing a surface acoustic wave device according to claim 1, further comprising a step of providing.

According to a fourth aspect of the present invention, the main surface side of the piezoelectric substrate is superposed on the second substrate on which the terminal electrode for establishing electrical connection with the outside is formed, and the protrusion on the piezoelectric substrate is formed. 3. The method of manufacturing a surface acoustic wave device according to claim 1, further comprising a step of electrically connecting an electrode and the terminal electrode.

The present invention according to claim 5 is the method of manufacturing a surface acoustic wave device according to claim 3, further comprising the step of shaving the insulator part to expose the protruding electrode.

According to a sixth aspect of the present invention, after the step of thinning the piezoelectric substrate, a step of providing a second insulating portion on the ground surface or the polished surface of the piezoelectric substrate is included. A method of manufacturing a surface acoustic wave device according to claim 3.

According to a seventh aspect of the present invention, in the method of manufacturing a surface acoustic wave device according to the first or second aspect, at least the step of thinning the piezoelectric substrate is performed, and then the surface acoustic wave device is cut into individual pieces. A method of manufacturing a surface acoustic wave device, comprising:

According to the present invention of claim 8, a plurality of piezoelectric substrates cut into individual pieces are superposed on a second substrate, and projecting electrodes on the piezoelectric substrate and terminals on the second substrate are stacked. 5. The method of manufacturing a surface acoustic wave device according to claim 4, wherein the electrode is electrically connected.

According to the present invention of claim 9 wherein the second substrate is
5. The method of manufacturing a surface acoustic wave device according to claim 4, wherein the method comprises at least a separator substrate and a terminal electrode, and includes a step of removing the separator substrate.

According to a tenth aspect of the present invention, the grain size of the abrasive grains in the step of thinning is in the range of # 160 to # 1200, and the production of the surface acoustic wave device according to the first or second aspect. Is the way.

The present invention according to claim 11 is the method of manufacturing a surface acoustic wave device according to claim 1 or 2, wherein the thinned piezoelectric substrate has a thickness within a range of 0.05 mm to 0.3 mm. Is the way.

The present invention according to claim 12 is the method of manufacturing a surface acoustic wave device according to claim 3, characterized in that the insulator portion is resin.

The present invention according to claim 13 is the method of manufacturing a surface acoustic wave device according to claim 1 or 2, wherein the piezoelectric substrate is a single crystal material made of lithium tantalate or lithium niobate. is there.

According to a fourteenth aspect of the present invention, a comb-shaped electrode for exciting surface acoustic waves and a space provided so as to surround at least a part of the comb-shaped electrode on the main surface of the piezoelectric substrate. A forming portion, a pad electrode electrically connected to the comb-shaped electrode, a protruding electrode arranged on the electrode pad portion, a terminal electrode electrically connected to the protruding electrode, and a main surface of the piezoelectric substrate. Of the insulator portion provided on at least a part of the piezoelectric substrate, and the piezoelectric substrate has a thickness of 0.05 mm to 0.3 m.
The surface acoustic wave device is characterized in that it is within the range of m and the surface roughness Ra of the other main surface of the piezoelectric substrate is 0.05 μm or more.

According to a fifteenth aspect of the present invention, a comb-shaped electrode for exciting a surface acoustic wave and a space provided so as to surround at least a part of the comb-shaped electrode on the main surface of the piezoelectric substrate. The forming portion, the pad electrode electrically connected to the comb-shaped electrode, the protruding electrode arranged on the electrode pad portion, the terminal electrode electrically connected to the protruding electrode, and the terminal electrode are formed. The second substrate, which has a thickness of 0.05 mm to 0.3 mm, and the surface roughness Ra of the other main surface of the piezoelectric substrate.
Is 0.05 μm or more.

According to a sixteenth aspect of the present invention, the surface acoustic wave device according to the fourteenth aspect is characterized in that the material forming the space forming portion and the insulating portion are made of the same material.

The present invention according to claim 17 is the surface acoustic wave device according to claim 14 or 15, wherein the piezoelectric substrate is a piezoelectric single crystal of lithium tantalate or lithium niobate.

The present invention according to claim 18 is the surface acoustic wave device according to claim 14, wherein the flexural modulus of the insulator is from 1.5 GPa to 8 GPa.

The present invention according to claim 19 is the surface acoustic wave device according to claim 14, characterized in that the insulator portion is made of resin.

The present invention according to claim 20 is the surface acoustic wave device according to claim 14 or 15, characterized in that a resin layer is formed on the other main surface of the piezoelectric substrate.

The present invention according to claim 21 is the surface acoustic wave device according to claim 14 or 15, characterized in that a metal layer is formed on the other main surface of the piezoelectric substrate.

[0034]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) A surface acoustic wave device according to Embodiment 1 of the present invention will be described with reference to FIG. 1A is a sectional view of the device, and FIG. 1B is a piezoelectric substrate 101.
It is a figure showing the functional part of the surface acoustic wave device formed above, and is a perspective view which looked at the principal surface direction in which the comb-shaped electrode of piezoelectric substrate 101 is formed in the height direction. Also, FIG.
The portion of dashed-dotted line AB in FIG. 1B corresponds to the cross-sectional view of FIG. As is clear from the figure, the alternate long and short dash line AB is bent at a right angle at the pad electrode 103 portion.

Next, the structure of the surface acoustic wave device according to this embodiment will be described with reference to the reference numerals. 101 is a piezoelectric substrate, such as lithium tantalate, lithium niobate,
A single crystal piezoelectric material such as quartz, potassium niobate, or langasite, or a substrate material in which a thin film material such as zinc oxide or aluminum nitride is provided on a specific substrate is used, but in this embodiment, a lithium tantalate substrate is used. Is used. The thickness of the piezoelectric substrate 101 is 100 μm. 10
2 is a comb-shaped electrode for exciting the surface acoustic wave. In the figure, only two pairs of one pair and six comb-shaped electrodes are shown, but in reality, several tens or more pairs of electrodes are alternately crossed, and in a filter or the like, such a pair is used. A plurality of comb electrode groups are arranged to form a surface acoustic wave element.

Reference numeral 103 denotes an electrode pad provided on the piezoelectric substrate 101, which serves to establish electrical continuity between the external electrode and the comb-shaped electrode 102. Although four pad electrodes 103 are shown in the figure, there are usually two or more pad electrodes and the number is not limited to four. Reference numeral 104 denotes a protruding electrode, which is electrically connected to the pad electrode 103. Further, in this embodiment, gold is used as the constituent material. The constituent material of the bump electrode is not limited to gold, and any material having conductivity may be used. For example, tin,
Lead, copper, silver, nickel, or an alloy containing at least one of them may be used. The number of the protruding electrodes 104 is also four in the figure, but in the present embodiment,
This is effective regardless of the number of protruding electrodes 104. 105 is a terminal electrode, which is electrically connected to the protruding electrode 104,
It consists of a metal whose main component is copper.

The constituent material of the terminal electrode 105 is not limited to copper, and any material having conductivity may be used. For example,
Tin, lead, chromium, titanium, gold, silver, palladium, nickel, an alloy containing at least one of them, or a stack of a plurality of the above metals may be used.

Reference numeral 106 denotes an insulating material, which is the piezoelectric substrate 101.
Is provided to protect the machine from mechanical damage. In the present embodiment, the epoxy-silicone modified resin is used, but the present invention is not limited to this. Any material may be used as long as it is not electrically conductive and has sufficient adhesion to the piezoelectric substrate 101 so that it does not peel off. For example, epoxy resin, silicone resin, acrylic resin, or the like may be used. Further, these materials may be filled with a filler such as silica, magnesia and alumina. Insulating material 10 of the present embodiment
6 is filled with silica.

Reference numeral 107 is a functional region where surface acoustic waves are excited and propagated. Basically, it is necessary to prevent the insulating material 106 from touching the functional region 107, and a space is formed by a member described later. However, the space may not be formed in a part of the functional area 107 as long as desired characteristics are obtained. Reference numeral 108 denotes a space forming portion, which indicates a space for protecting the functional area. 109,
Reference numerals 110 respectively denote a wall portion and a roof portion for forming a space, and the space is formed by arranging them so as to cover the functional area 107.

In the present embodiment, the wall portion 109 and the roof portion 11
Although a resin material is used as the material of 0, the material is not limited to this. In short, any material that can form a space without being affected by the insulating material 106 or the like may be used.

The size of the surface acoustic wave device according to this embodiment is 1.2 mm in length, 1.5 mm in width, and 0.
It is 18 mm. The height of the piezoelectric substrate 101 is 0.1.
The height of the insulating material 106 and the terminal electrode 105 is 0.08 mm.

Next, the manufacturing method of the embodiment will be described with reference to FIGS. The manufacturing method of the present embodiment was used for manufacturing the surface acoustic wave device described in the first embodiment. Further, although the drawing only shows two surface acoustic wave devices, in the present embodiment, the following steps were performed in a state in which a plurality of devices were formed on a 4-inch wafer.

The comb-shaped electrode 102 and the pad electrode 103 are formed on the piezoelectric substrate 101 by photolithography. As shown in FIG. 2, a wall portion 109 is provided so as to surround the functional area 107, and a roof portion 110 is further provided.
The wall portion 109 and the roof portion 110 are formed by photolithography using a photosensitive resin material. The comb-shaped electrode 102 and the pad electrode 103 are not shown in the figure.

Next, as shown in FIG. 3, a protruding electrode 104 is provided. A gold wire is ball-bonded onto the pad electrode 103 by a bump bonder, and is torn off to form a bump. Next, as shown in FIG.
Apply 6. The application was performed using a dispenser. Further, heat treatment was performed to cure the insulating material 106.

Next, as shown in FIG. 5, the insulating material 106 is ground to expose the protruding electrodes 104. Next, as shown in FIG. 6, at least a part intersects the exposed bump electrode 104, and the terminal electrode 105 is formed so that electrical conduction can be obtained. The terminal electrode 105 was formed by sputtering with masking using a metal mask. The terminal electrode 1
05 may be formed by vacuum vapor deposition, ion plating, or the like, or may be formed by screen-printing or curing a conductive resin or the like.

Next, as shown in FIG. 7, the piezoelectric substrate 101 is thinned by grinding to 0.35 mm to 0.1 mm. As the fixed abrasive for grinding, # 360 was used. It is preferable to use # 800 or less fixed abrasive grains because of the influence of the back surface reflection on the device characteristics. The reason why the roughness of the abrasive grains must be made coarser than that of lapping is that in the case of grinding, grinding marks are periodically formed and the reflected waves from the back surface do not cancel each other out well. When the fixed abrasive grains of # 600 and # 360 are used, the thickness of the piezoelectric substrate 101 is 0.3 mm, 0.25
Even if the thickness was set to mm, 0.2 mm, 0.15 mm, or 0.1 mm, the characteristics of the device did not deteriorate. The characteristic deterioration here means that when a filter is used as the surface acoustic wave device, the insertion loss within a predetermined band is within a predetermined value. For example, in the present embodiment, 40
The insertion loss within the pass band of MHz was within -3 dB to -4 dB. At this time, the maximum difference between the maximum and minimum ripples in the pass band between the ground product and the non-ground product was 0.2 dB.

The thickness of the piezoelectric substrate 101 is 0.15 m.
m and the fixed abrasive grain size was changed to # 700 and # 800 to perform grinding. Also, if the fixed abrasive grains are made too coarse, the grinding marks and the work-affected layer become deeper,
There are cases where the characteristics of the device are deteriorated or cracks occur during grinding. Therefore, it is preferably # 160 or more. A method such as polishing or sandblasting may be used for thinning. When polishing is used for thinning, the grain size of the abrasive grains is preferably # 1200 or less. Next, the device is individually diced along the broken line in FIG.

The surface acoustic wave device of the present embodiment is 1/3 of the surface acoustic wave device of FIG. 22 described in the conventional example.
There is an effect that the height can be reduced to the following heights. This is because the height of the piezoelectric substrate 101 is 0.35 to 0.40 of the conventional one.
This is due to the change from mm to 0.1 mm. Further, the resistance to mechanical shock caused by thinning the piezoelectric substrate 101 is mitigated because of the insulating material 106. Further, in the case of the structure without the usual insulating material 106, when the thickness of the piezoelectric substrate 101 is 0.1 mm, the main surface is mirror-finished, and the back surface is ground with, for example, # 360 fixed abrasive,
The surface acoustic wave device is largely warped and cannot be secondarily mounted. However, the secondary mounting here means mounting the surface acoustic wave device on another substrate or the like.

The following effects can be obtained by the method of manufacturing the surface acoustic wave device described in this embodiment. First, since the piezoelectric substrate 101 is thinned after the device is manufactured on the wafer, the problems described in the conventional example are greatly reduced and the height of the device can be easily reduced. In addition, the yield is increased and the cost can be reduced.

Secondly, by dicing the piezoelectric substrate 101 after thinning it, chipping of the piezoelectric substrate 101, damage to the blade, etc. can be reduced even if the dicing speed is increased. Actually, the area of the chipping portion of the apparatus cut at a speed of 4 mm / sec in the state shown in FIG. 6 and the apparatus cut at a speed of 12 mm / sec in the apparatus cut in the case of FIG. The device I did was smaller. As a result, manufacturing tact is improved, defects due to chipping are reduced, and cost can be reduced. Further, since the chipping portion is small, the margin of the outer peripheral portion of the device can be reduced, and the area of the device can be reduced. Further, the load on the dicing blade is reduced, the maintenance cycle for dressing the blade is lengthened, the wear amount of the blade is reduced, and the blade replacement cycle is extended. Actually, at the same cutting speed, when comparing the thin plate and the thin plate, both the maintenance cycle and the replacement cycle were improved by more than 5 times.

Thirdly, the insulating material 10 is formed on the piezoelectric substrate 101.
Since the thinning is performed after providing 6, the damage of the piezoelectric substrate 101 during the thinning process is reduced. Also, the insulating material 106
Is a member that constitutes the surface acoustic wave device,
Since it is not necessary to remove it, the manufacturing yield after the thinning process is also improved. Fourthly, since the wafer can be thinned, the productivity can be improved and the cost can be reduced.
Fifth, thinned piezoelectric substrate 101, which was difficult in the past
Since the device can be configured by using, the weight of the entire device is reduced, the device is resistant to the drop test, and the reliability of the element is improved.

In the manufacturing method of the present embodiment described above, the 4-inch wafer was processed before the cutting step by dicing, but the present invention is not limited to this, and the point is that it is easy to handle and suits mass production. It should be processed according to the size.

The thickness of the piezoelectric substrate 101 of this embodiment is 0.1 mm, but the thickness is not limited to this. In particular, thinning may be performed according to the desired size of the device.

Further, among the piezoelectric single crystal materials, lithium tantalate and lithium niobate have a particularly strong cleavage property and are easily cracked. Therefore, the configuration of this embodiment has a great effect.

The insulating material 10 used in this embodiment is also used.
6 is an epoxy-silicone modified resin and has a flexural modulus of 6
It is GPa. When the bending elastic modulus is decreased, the warp of the surface acoustic wave device becomes large, and a part which is not soldered to the electrode appears at the time of secondary mounting, which may cause a problem that the surface acoustic wave device rises or shifts. Therefore, the flexural modulus is preferably 1.5 GPa or more. Further, if the bending elastic modulus is increased, the warp of the wafer increases at the stage where the insulating material 106 is applied and cured, and the substrate is cracked during grinding, or during curing.
Problems such as cracking of the wafer occur after curing. For example,
Using lithium tantalate and lithium niobate, 10
When manufactured using the insulating material 106 of GPa or more, 20% cracked when the insulating material 106 was cured, and the other half caused a crack due to cracking during grinding. Therefore, it is preferable that the flexural modulus is 8 GPa or less.

(Embodiment 2) Next, a manufacturing method according to Embodiment 2 of the present invention will be described. The explanation is shown in Figs.
Using. In the manufacturing method of the present embodiment, a double-side polished substrate is used as the piezoelectric substrate 101. The manufacturing process of the piezoelectric substrate 101 will be described below. The ingot is cut on a wafer with a wire saw. The wafer is lapped by double-side polishing to a predetermined thickness.
Further, both sides are polished and mirror-finished. The surface acoustic wave device is manufactured by the manufacturing process described in the second embodiment using the piezoelectric substrate 101 manufactured in the above process.

The manufacturing method of this embodiment has the following effects. First of all, since a piezoelectric substrate having both surfaces polished is used as the piezoelectric substrate 101, the piezoelectric substrate 101
The warp is smaller than that of the piezoelectric substrate used in the second embodiment, the characteristic variation in the wafer is reduced, and the manufacturing yield of the surface acoustic wave device is improved. It should be noted that this is largely due to the effect of reducing defects in the photolithography process of the comb electrodes. Secondly, the manufacturing process of the piezoelectric substrate 101 can be simplified, leading to cost reduction. For example,
In order to manufacture a conventional piezoelectric substrate having a mirror-finished surface and a rough back surface, a step of roughening the back surface after double-side polishing is required. In the case where only the front surface is polished by the single-sided polishing, the number of steps is the same, but sagging occurs at the end and unevenness in the thickness of the wafer occurs, which leads to deterioration in the yield of the surface acoustic wave device.

(Embodiment 3) A surface acoustic wave device according to Embodiment 3 of the present invention will be described with reference to FIG. Figure 8
111 is an insulating material, for example, an epoxy resin. The insulating material 111 is arranged on the back surface side of the piezoelectric substrate 101.

Next, a method of manufacturing the surface acoustic wave device of this embodiment will be described. After the thinning process described with reference to FIG. 7, the insulating material 111 is applied to the entire surface. The application was performed with a dispenser, and the height was controlled by performing curing in a mold whose inner wall was coated with Teflon (registered trademark). Also,
The insulating material 111 is an epoxy resin. The insulating material 111 may be applied by a printing method, a spin coating method, or the like.

The structure described above has the following effects. First of all, it is possible to reduce the warpage of the surface acoustic wave device, and it is possible to reduce problems when the surface acoustic wave device is secondarily mounted. This warp is caused by the insulating material 106 and the piezoelectric substrate 10.
1 caused by the difference in elastic modulus and thermal expansion coefficient and the hardening and shrinkage of the resin used as the insulating material 106.
The thinner 01 is, the larger the warp amount is. The first effect is greatest when the insulating material 106 and the second insulating material 111 are the same material. Further, as the insulating material 106, a material having a high glass transition point and a high elastic modulus can be selected, and the reliability of the device is improved. The insulating material 106 used in this embodiment has a bending elastic modulus of 8 GP.
The thing of a was used. Secondly, it is possible to reduce the impact at the time of mounting by an automatic machine such as a chip mounter. Thirdly, the heat capacity of the surface acoustic wave device is increased, and the reliability of tests such as heat shock is improved.

According to the manufacturing method of the present embodiment, it is possible to easily manufacture a surface acoustic wave device that balances the bending stress in the thickness direction and has less warpage and high reliability.

(Embodiment 4) A surface acoustic wave device according to Embodiment 4 of the present invention will be described with reference to FIG.
In FIG. 9, 112 is a metal body, for example, copper formed by the combination of sputtering and plating.

The structure of this embodiment has the following effects. First of all, the heat dissipation is better and the resistance to pyroelectric breakdown is higher. Further, even when the heating is performed rapidly, the heat is uniformly transferred to the front surface of the piezoelectric substrate 101, so that a local temperature rise can be avoided. In particular, these effects are very effective when the piezoelectric substrate 101 is thin. Second
In addition, it has an electric shield effect. The surface acoustic wave device is often used in a high frequency region such as a quasi-microwave band, and may be mounted on the same substrate as other high frequency components, so that an electric shield may be required.

(Fifth Embodiment) A surface acoustic wave device according to a fifth embodiment of the present invention will be described with reference to FIG. In FIG. 10, reference numeral 113 is a protruding electrode. In Figure 10 (b)
FIG. 10 is a view of the surface acoustic wave device as seen from the main surface side on which the comb-shaped electrodes are formed, and FIG. 10A is a cross-sectional view taken along the broken line AB. Note that FIG. 10B is not a perspective view unlike FIG. 1B.

In the structure of the present embodiment, the pad electrode 10
3 is provided with a protruding electrode 113 to establish electrical connection with the outside. The wall portion 109 is provided on the front surface other than the space forming portion 108, and the roof portion 110 is provided on the entire area other than the solder bumps. The material of the roof 109 is
It is only necessary that the space forming portion 108 can be formed and that it is insulating.

Next, a method of manufacturing the surface acoustic wave device of this embodiment will be described. Similar to the first embodiment, up to the pad electrode 103 is provided. In the present embodiment, the acrylic photosensitive dry film resist is laminated on the front surface of the substrate, and the space forming portion 108 is provided by the photolithography technique to form the wall portion 109. Next, roof part 1
10 is further laminated with the same material, and the portion where the protruding electrode 113 is provided is removed in a later step. This step is also performed by the same photolithography technique. In addition to the acrylic type, a photosensitive resin such as polyimide or another photosensitive resin may be used. For example, a liquid polyimide resin is spin-coated on the entire surface, and the space forming portion 108 is formed by a photolithography technique. In addition, the wall portion 109 and the roof portion 110
Does not have to be the same material as long as it can form a space.

Next, cream solder is applied onto the pad electrode 103 by printing and heated, whereby the protruding electrode 11 is formed.
3 is formed. The heating was performed by reflowing in a nitrogen atmosphere at a temperature at which the solder melted or higher. In the present embodiment, the solder bumps that are the protruding electrodes 113 are formed by printing and heating, but they may be formed by mounting solder balls on the pad electrodes 103 and heating them.

In this embodiment, solder bumps are used as the protruding electrodes, but protruding bumps made of another metal may be used as in the first embodiment. For example, copper or nickel may be generated by plating, or a tear-off bump may be used. Next, the other principal surface, which is the surface opposite to the functional region 107 of the piezoelectric substrate 101, is thinned by the method described in the first embodiment.

By the structure and the manufacturing method described above, the same effect as the effect described in the first embodiment can be obtained, but the wall portion 109 forming the space forming portion 108 and the roof portion 110 are further provided in the embodiment. By using the insulating material 106 described in Section 1, the structure is simplified and the size can be reduced.
Also, the manufacturing cost is reduced.

(Sixth Embodiment) A surface acoustic wave device according to a sixth embodiment of the present invention will be described with reference to FIGS. In FIG. 11, 114 is an interposer 117.
An upper layer electrode formed above, 115 is a via electrode penetrating the front and back of the interposer, and 116 is a terminal electrode provided on the lower surface of the interposer,
It is for electrical connection with the outside. Reference numeral 117 denotes an interposer, which is a glass epoxy substrate in this embodiment. The interposer 117 is
The substrate is not limited to this, and may be a Teflon-based substrate, a polyimide-based substrate, a film-shaped substrate, a ceramic substrate, or the like.

Unlike the structure described in the first embodiment, the surface acoustic wave device of the present embodiment does not have the wall portion 109 and the roof portion 110 for forming the space forming portion 108, and will be described in the first embodiment. The space forming portion 108 is formed by a member corresponding to the insulating material 106.

Next, a method of manufacturing the surface acoustic wave device according to this embodiment will be described with reference to FIGS. Figure 1
2, the comb-shaped electrode 102, the pad electrode 103, and the protruding electrode 104 are formed on the piezoelectric substrate 101. Next, as shown in FIG. 13, the piezoelectric substrate 10 previously divided into individual parts.
1 is mounted on the interposer 117. Mounting is performed by applying pressure while applying ultrasonic waves. Here, the surface of the surface layer electrode 114 is made of gold, and
The protruding electrode 104 is also gold. Next, as shown in FIG. 14, the insulating material 106 is injected by a dispenser.
Unlike the resin material described in the first embodiment, the insulating material 106 is a resin material having a high viscosity and thus does not penetrate into the functional region 107. Next, the resin material is cured by heating. At this time, the viscosity of the insulating material 106 is lower than that in the state shown in FIG. 14, but as shown in FIG. 15, it does not penetrate into the functional region 107. Next, as shown in FIG. 16, the insulating material 106 and the piezoelectric substrate 101 are thinned.

By the structure and manufacturing method of the surface acoustic wave device of this embodiment, the same effects as described in the first embodiment can be obtained, but further the following effects are obtained.

Generally, in a mode in which the piezoelectric substrate on which the comb-shaped electrodes are formed and the projecting electrodes are formed via the interposer as shown in FIG. 11, the interposer 117 is compared with the piezoelectric substrate 101. If it is thick, there is a problem that the device warps. As a result, a chip standing defect called Manhattan occurred during the reflow of the secondary mounting, or a defect that the mounting could not be performed properly occurred during the mounting. In the present embodiment, since the piezoelectric substrate 101 and the interposer 117 have approximately the same thickness, there is almost no warpage, and the above-mentioned problems are greatly reduced. Further, by thinning the piezoelectric substrate 101, the excess insulating material 106 can be removed at the same time, and the problem at the time of secondary mounting chip mounting can be eliminated. Usually, in a chip component such as a surface acoustic wave device, the back surface thereof, here, the other main surface side of the piezoelectric substrate 101 is adsorbed to the head portion of the chip mounter by a method such as vacuum adsorption, and mounted on a target substrate. . At this time, if there is a large unevenness on the back surface, a suction error or a chip shift during mounting occurs.

(Embodiment 7) A surface acoustic wave device according to Embodiment 7 of the present invention will be described with reference to FIGS. Unlike the manufacturing method described in the first embodiment, the present embodiment does not require grinding of the insulating material 106. The manufacturing method will be described below.

As shown in FIG. 18, on the piezoelectric substrate 101, the comb-shaped electrode, the wall portion 109, the roof portion 110, and the pad electrode 10 are formed.
3. Protrusion electrodes 104 are provided. Here, although the comb-shaped electrode is not shown, it is provided in the same place as in the first embodiment. At the same time, the liquid insulating material 106 is applied on the carrier in which the terminal electrode 105 is patterned on the separator. Next, as shown in FIG.
The piezoelectric substrate 10 so that the predetermined terminal electrode 105 and the predetermined terminal electrode 105 overlap.
1 and the carrier consisting of the separator 118 and the terminal electrode 105 are superposed. At the same time, the insulating material 106 is cured. The insulating material 106 is cured by heat treatment in this embodiment. In this embodiment, the protruding electrode 104 is made of gold, and at least the surface layer of the terminal electrode 105 is solder-plated.

Next, heat treatment is applied at a temperature at which the solder is melted and the terminal electrodes 105 and the protruding electrodes 104 are fixed. Next, as shown in FIG. 20, the separator 118 is removed. Finally, as shown in FIG. 17, it is divided into individual devices by dicing.

The manufacturing method of the present embodiment simplifies the process of the apparatus in addition to the effects described in the first embodiment.
This leads to cost reduction of the element.

[0080]

The surface acoustic wave device of the present invention described above,
According to the manufacturing method and the manufacturing method thereof, it is possible to easily realize a small-sized, particularly low-profile, highly reliable surface acoustic wave device at low cost.

[Brief description of drawings]

FIG. 1 is a diagram showing a surface acoustic wave device of the present invention.

FIG. 2 is a diagram showing a method for manufacturing a surface acoustic wave device of the present invention.

FIG. 3 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 4 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 5 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 6 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 7 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 8 is a diagram showing a surface acoustic wave device of the present invention.

FIG. 9 is a diagram showing a surface acoustic wave device of the present invention.

FIG. 10 is a diagram showing a surface acoustic wave device of the present invention.

FIG. 11 is a diagram showing a surface acoustic wave device of the present invention.

FIG. 12 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 13 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 14 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 15 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 16 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 17 is a diagram showing a surface acoustic wave device of the present invention.

FIG. 18 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 19 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 20 is a diagram showing a method of manufacturing the surface acoustic wave device of the present invention.

FIG. 21 is a diagram showing a conventional surface acoustic wave device.

FIG. 22 is a diagram showing a conventional surface acoustic wave device.

[Explanation of symbols]

101 Piezoelectric substrate 102 comb-shaped electrode 103 pad electrode 104 protruding electrode 105 terminal electrode 106 insulating material 107 functional areas 108 Space Forming Unit 109 wall 110 roof 111 Insulation material 112 metal body 113 Projection electrode (solder bump) 114 upper electrode 115 Via electrode 116 terminal electrode 117 Interposer 118 separator

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsunori Moritoki             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Kunihiro Fujii             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F term (reference) 5J097 AA29 AA33 HA04 HA07 HA08                       HA09 JJ01 JJ03 JJ06 JJ10                       KK09 KK10

Claims (21)

[Claims] 1. A step of providing a comb-shaped electrode for exciting a surface acoustic wave and a pad electrode electrically connected to the comb-shaped electrode on one main surface of the piezoelectric substrate, and at least the comb-shaped electrode. A step of providing a space forming portion provided so as to surround the above, a step of providing a protruding electrode on the pad electrode, a main surface side of the piezoelectric substrate is fixed to a pedestal, and the other main surface of the piezoelectric substrate is ground. Or a step of polishing to reduce the thickness of the piezoelectric substrate, and a method of manufacturing a surface acoustic wave device. 2. A step of polishing both surfaces of a piezoelectric substrate to give a mirror finish, a comb-shaped electrode for exciting a surface acoustic wave on one main surface of the piezoelectric substrate, and a pad electrically connected to the comb-shaped electrode. A step of providing an electrode, a step of providing a space forming portion provided so as to surround at least a part of the comb-shaped electrode, a step of providing a protruding electrode on the pad electrode, and a main surface side of the piezoelectric substrate Is fixed to a pedestal, and the other main surface of the piezoelectric substrate is ground or polished to thin the piezoelectric substrate, and a method for manufacturing a surface acoustic wave device. 3. A step of providing an insulator portion on the main surface side of the piezoelectric substrate so as to cover the space forming portion, and a step of providing a terminal electrode electrically connected to the protruding electrode. The method for manufacturing a surface acoustic wave device according to claim 1 or 2, characterized in that: 4. A main surface side of a piezoelectric substrate is superposed on a second substrate on which a terminal electrode for establishing electrical connection with the outside is formed, and a protrusion electrode on the piezoelectric substrate and the terminal electrode are formed. The method for manufacturing a surface acoustic wave device according to claim 1, further comprising a step of establishing electrical continuity. 5. The method of manufacturing a surface acoustic wave device according to claim 3, further comprising the step of shaving the insulator part to expose the protruding electrode. 6. The elastic surface according to claim 3, further comprising a step of providing a second insulating portion on a ground surface or a polished surface of the piezoelectric substrate after the step of thinning the piezoelectric substrate. Wave device manufacturing method. 7. The method of manufacturing a surface acoustic wave device according to claim 1, further comprising a step of cutting the surface acoustic wave device into individual pieces after performing at least the step of thinning the piezoelectric substrate. A method for manufacturing a surface acoustic wave device. 8. A plurality of piezoelectric substrates cut into pieces are superposed on a second substrate, and projecting electrodes on the piezoelectric substrate are provided.
5. The method of manufacturing a surface acoustic wave device according to claim 4, wherein the terminal electrode on the second substrate is electrically connected. 9. The method of manufacturing a surface acoustic wave device according to claim 4, wherein the second substrate is composed of at least a separator substrate and a terminal electrode, and includes a step of removing the separator substrate. 10. The grain size of abrasive grains in the step of thinning is #.
The method for manufacturing a surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is in the range of 160 to # 1200. 11. The thinned piezoelectric substrate has a thickness of 0.05 m.
3. The method for manufacturing a surface acoustic wave device according to claim 1, wherein the surface acoustic wave device is in the range of m to 0.3 mm. 12. The method of manufacturing a surface acoustic wave device according to claim 3, wherein the insulator part is resin. 13. The method of manufacturing a surface acoustic wave device according to claim 1, wherein the piezoelectric substrate is a single crystal material made of lithium tantalate or lithium niobate. 14. A comb-shaped electrode for exciting a surface acoustic wave on a main surface of a piezoelectric substrate, a space forming portion provided so as to surround at least a part of the comb-shaped electrode, and the comb-shaped electrode. A pad electrode electrically connected to the electrode, a protruding electrode arranged in the electrode pad portion, a terminal electrode electrically connected to the protruding electrode, and provided on at least a part of the main surface of the piezoelectric substrate. And a thickness of the piezoelectric substrate within a range of 0.05 mm to 0.3 mm, and
The surface roughness Ra of the other main surface of the piezoelectric substrate is 0.05 μm.
The above is a surface acoustic wave device characterized by the above. 15. A comb-shaped electrode for exciting a surface acoustic wave on a main surface of a piezoelectric substrate, a space forming portion provided so as to surround at least a part of the comb-shaped electrode, and the comb-shaped electrode. A pad electrode electrically connected to an electrode, a protruding electrode arranged in the electrode pad portion, a terminal electrode electrically connected to the protruding electrode, and a second terminal electrode formed therein.
The piezoelectric substrate has a thickness of 0.05 m
A surface acoustic wave device having a surface roughness Ra of m to 0.3 mm and a surface roughness Ra of the other main surface of the piezoelectric substrate of 0.05 μm or more. 16. The material forming the space forming portion and the insulating portion are made of the same material.
The surface acoustic wave device described. 17. The surface acoustic wave device according to claim 14, wherein the piezoelectric substrate is a piezoelectric single crystal of lithium tantalate or lithium niobate. 18. The surface acoustic wave device according to claim 14, wherein the insulator has a bending elastic modulus of 1.5 GPa to 8 GPa. 19. The surface acoustic wave device according to claim 14, wherein the insulator portion is made of resin. 20. The surface acoustic wave device according to claim 14, wherein a resin layer is formed on the other main surface of the piezoelectric substrate. 21. The surface acoustic wave device according to claim 14, wherein a metal layer is formed on the other main surface of the piezoelectric substrate.