JP2008153957A - Hollow sealing element, its manufacturing method and mobile communication equipment using hollow sealing element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hollow sealing element which is excellent in moisture proof reliability, is at a low cost and has high production efficiency. <P>SOLUTION: The hollow sealing element is constituted so that a functional part 20 having a mechanical movable part, an internal electrode 70 and a spacer layer 40 surrounding the functional part 20 and the internal electrode 70 are formed on an insulation substrate 10, a cover layer 50 is installed on them, a gap 90 is formed between the functional part 20 and the cover layer 50 and sealed, wherein the entire surface of the functional part 20 and the internal electrode 70 is covered with a protective film 30 which does not make moisture permeation. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a miniaturized packaging technology for a hollow sealing element such as a surface acoustic wave device used in a mobile communication device such as a mobile phone.

  A surface acoustic wave device mounted on a mobile communication device or the like does not reduce the surface acoustic wave transmission efficiency, and therefore requires a gap above the comb electrode. Conventionally, a surface acoustic wave chip is die-bonded face-up to a ceramic casing and electrically connected by wire bonding, and then covered with a metal cap and sealed by seam welding or soldering for packaging.

Recently, in order to reduce the size of devices, surface acoustic wave chips are flip-chip bonded (face-down die bonding) to wiring boards with Au bumps or solder bumps, and sealed with synthetic resin to form a small package device. It was.
To further reduce the size and height, the entire piezoelectric substrate wafer is sealed with a synthetic resin or the like while keeping a gap above each comb-shaped electrode, and external electrodes are formed. A small chip size package device is described in Japanese Patent Application Laid-Open No. 2004-147220 (Patent Document 1).

  However, even though the sealing structure using the resin described above can protect the comb electrode from dust and foreign matter, it cannot prevent the penetration of moisture that passes through the resin. For this reason, a device structure in which the comb electrode is covered with a protective film that does not transmit moisture has been proposed.

  FIG. 6 is a cross-sectional view of the device structure described in Japanese Patent Laid-Open No. 2006-217226 (Patent Document 2). As shown in the figure, the comb-shaped electrode 20 formed on the main surface of the piezoelectric substrate 10 of the surface acoustic wave device 200 is covered with a SiN protective film 30 that does not transmit moisture, and a spacer layer 40 made of a photosensitive resin and a cover. The layer 50 has a structure in which a gap 90 is formed and sealed above the comb-shaped electrode 20. With this structure, intrusion of dust and foreign matters can be prevented by the spacer layer 40 and the cover layer 50, and moisture can be prevented by the SiN protective film 30.

Although not shown in Japanese Patent Laid-Open No. 2006-217226 (Patent Document 2), FIG. 6 shows the bump 60 and the internal electrode 70 connected thereto.
JP 2004-147220 A JP 2006-217226 A

However, the conventional structure shown in FIG. 6 has the following problems.
That is, in this surface acoustic wave device, the protective film 30 that prevents moisture from entering is only the comb-tooth electrode 20 formed under the gap 90, and the structure that protects the internal electrode 70 under the spacer layer 40. It is not. For this reason, the internal electrode 70 made of the same metal material as the main component of the same aluminum (Al) as the comb electrode 20 is usually corroded by moisture that has penetrated through the cover layer 50 and the spacer layer 40. There was a problem with moisture resistance reliability.

  Further, in the conventional method of manufacturing a surface acoustic wave device, when forming the protective film 30 of the comb-tooth electrode 20 formed under the gap 90, some patterning process is required. In this patterning process, a mask for forming the pattern of the protective film 30 is necessary, and there is a problem that the manufacturing cost is increased accordingly.

  Further, until the spacer layer 40 is formed, the portion that is not covered with the protective film 30 may be damaged by dust and the like, and may corrode therefrom, causing a reduction in production yield.

  An object of the present invention is to eliminate such drawbacks of the prior art, to provide a hollow sealing element with excellent moisture resistance reliability, low cost and high production efficiency, a manufacturing method thereof, and a mobile communication device using the hollow sealing element Is to provide.

In order to achieve the above object, a first means of the present invention includes a functional part having a mechanically movable part, an internal electrode electrically connected to the functional part, and a spacer layer surrounding the functional part and the internal electrode. Is formed on an insulating substrate,
A hollow having a cover layer on the functional part, the internal electrode and the spacer layer, a gap is formed between the functional part and the cover layer, and an opening of the spacer layer is sealed by the cover layer In the sealing element,
The entire surface of the functional part and the internal electrode is covered with a protective film that does not transmit moisture.

  According to a second means of the present invention, in the first means, the protective film is continuously formed from the surface of the functional part and the internal electrode to the surface of the insulating substrate.

  According to a third means of the present invention, in the first or second means, the functional part and the internal electrode are made of a material mainly composed of aluminum.

  According to a fourth means of the present invention, in the first to third means, the protective film is composed of a silicon oxide film, a silicon nitride film, or a diamond-like carbon film.

  According to a fifth means of the present invention, in the first to fourth means, the insulating substrate is a piezoelectric substrate, and the mechanically movable portion is a comb electrode.

According to a sixth means of the present invention, a set of functional parts having mechanically movable parts and internal electrodes electrically connected to the functional parts are formed as a set on the insulating substrate at a predetermined interval. And a process of
Covering the entire upper surface of the insulating substrate on which the functional part and the internal electrode are formed with a protective film that does not transmit moisture;
A photosensitive resin layer is formed on the entire upper surface of the insulating substrate covered with the protective film, and a portion corresponding to the functional portion, the via hole portion corresponding to the connection portion of the internal electrode to the external electrode, and the dicing portion is photolithography method And removing the patterning to form a spacer layer;
Laminating a photosensitive resin film on the entire upper surface of the insulating substrate on which the spacer layer is formed, and forming a cover layer by patterning and removing portions corresponding to the via hole portion and the dicing portion by a photolithography method; ,
Removing the protective film at a position corresponding to the bottom of the via hole portion and the dicing portion using the spacer layer and the cover layer as a mask;
Forming an external electrode by plating from the via hole portion to the external electrode forming portion on the cover layer;
And dicing the dicing section to separate individual devices.

According to a seventh means of the present invention, a set of functional parts having mechanically movable parts and internal electrodes electrically connected to the functional parts are formed as a set at a predetermined interval on an insulating substrate. And a process of
Covering the entire upper surface of the insulating substrate on which the functional part and the internal electrode are formed with a protective film that does not transmit moisture;
A photosensitive resin layer is formed on the entire upper surface of the insulating substrate covered with the protective film, and a portion corresponding to the function part and the via hole part corresponding to the connection part of the internal electrode to the external electrode is patterned by a photolithography method. Removing to form a spacer layer;
Laminating a photosensitive resin film on the entire upper surface of the insulating substrate on which the spacer layer is formed, and forming a cover layer by removing a pattern corresponding to the via hole portion by photolithography,
Removing the protective film at a location corresponding to the bottom of the via hole portion using the spacer layer and the cover layer as a mask;
Forming an external electrode by plating from the via hole portion to the external electrode forming portion on the cover layer;
And dicing the dicing section to separate individual devices.

  According to an eighth means of the present invention, in the sixth or seventh means, the functional part and the internal electrode are made of a material mainly composed of aluminum, and the protective film is a silicon oxide film, a silicon nitride film, or a diamond-like material. It is characterized by comprising a carbon film.

  According to a ninth means of the present invention, in the sixth to eighth means, a reverse sputtering method, a dry etching method or an etching method using a hydrogen fluoride-based chemical agent is used as the method for removing the protective film. It is.

  According to a tenth means of the present invention, in the sixth to ninth means, the insulating substrate is a piezoelectric substrate, and the mechanically movable portion is a comb electrode.

  The eleventh means of the present invention is characterized in that, in a mobile communication device equipped with a high frequency filter, the high frequency filter is the hollow sealing element according to claim 5.

  The present invention has a configuration as described above, and provides a hollow sealing element having excellent moisture resistance reliability, low cost and high production efficiency, a manufacturing method thereof, and a mobile communication device using the hollow sealing element. Can do.

  Next, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of the surface acoustic wave device according to the first embodiment.

In the figure, reference numeral 10 denotes a piezoelectric substrate made of LiTaO ₃ or LiNbO ₃ as a base material of the surface acoustic wave device 100, and a comb-like electrode 20 mainly composed of Al is formed on the main surface thereof. At the same time, an internal electrode 70 made of the same material is electrically connected to the comb electrode 20, and the internal electrode 70 is connected to the external electrode 80 through a via hole portion 81. The external electrode 80 includes a power supply film 82 and a solder layer 83.

  The comb-teeth electrode 20 is a functional part (mechanically movable part) that mechanically moves to transmit surface acoustic waves, and does not reduce the surface acoustic wave transmission efficiency above the comb-teeth electrode 20. A space 90 is formed by the spacer layer 40 and the cover layer 50, and the opening of the spacer layer 40 is sealed with the cover layer 50.

  In order to ensure moisture resistance, the comb-shaped electrode 20 and the internal electrode 70 having Al as a main component, all of the piezoelectric substrate 10, the comb-shaped electrode 20, and the internal electrode 70 except for the via hole portion 81 and the dicing portion (described later) 12 are used. Is covered with a protective film 30. The purpose of the protective film 30 is to prevent moisture from entering, but a moisture-proof film that is as thin as possible is required in order not to reduce the surface acoustic wave transmission efficiency. In this embodiment, an inorganic insulating film such as a silicon oxide film, a silicon nitride film, or a diamond-like carbon film is coated with a thickness of 3 nm to 30 nm, preferably 5 nm to 10 nm. If the thickness of the protective film 30 is less than 3 nm, the moisture-proof effect is insufficient due to the formation of pinholes and the like. On the other hand, if the thickness of the protective film 30 exceeds 30 nm, the surface acoustic wave transmission efficiency tends to decrease. The film thickness was regulated within the aforementioned range.

  Although there is an organic material as a material of the protective film, a film made of an organic material itself contains a very small amount of moisture, so that it is not suitable as the protective film 30 for the comb-shaped electrode 20 mainly composed of Al and the internal electrode 70. It is. On the other hand, the protective film 30 made of the silicon oxide film, the silicon nitride film or the diamond-like carbon film has a dense structure, and substantially prevents the permeation of moisture even as a thin film as described above. Therefore, the moisture resistance effect can be sufficiently exhibited.

  Next, a method for manufacturing the surface acoustic wave device 100 will be described with reference to FIGS. The vertical broken line in the figure shows the dicing part 12, and the area between the broken lines is an area corresponding to one surface acoustic wave device, and is separated into individual surface acoustic wave devices 100 by dicing at the end of the process.

First, in FIG. 3A, a wide piezoelectric substrate wafer 11 made of LiTaO ₃ or LiNbO ₃ is prepared.

  Next, in FIG. 3B, a comb electrode material film 21 mainly composed of Al to be the comb electrode 20 and the internal electrode 70 is formed on the piezoelectric substrate wafer 11 by sputtering or vapor deposition.

  Next, in FIG. 3 (3), an etching resist (not shown) is spin-coated on the comb electrode material film 21, and a pattern other than the comb electrode 20 part and the internal electrode 70 part is patterned using a photolithography method. Remove ning. Subsequently, the comb-tooth electrode material film 21 is removed by etching using an etching resist (not shown) as a mask. Finally, the etching resist (not shown) is dissolved and removed with an organic solvent, and the comb-tooth electrode 20 and the internal electrode 70 are removed. Integrally formed.

  Next, in FIG. 3 (4), an inorganic insulating material such as a silicon oxide film, a silicon nitride film, or a diamond-like carbon film is sputtered on the entire surface of the piezoelectric substrate wafer 11 on which the comb electrodes 20 and the internal electrodes 70 are formed. A protective film 30 is formed by a chemical vapor deposition method with a thickness of 3 nm to 30 nm.

  Next, in FIG. 3 (5), a spacer material 41 made of a photosensitive resin film made of, for example, an acrylic resin or an epoxy resin is laminated on the entire surface of the piezoelectric substrate wafer 11 covered with the protective film 30. In the present embodiment, the laminate film of the spacer material 41 is used. However, a photosensitive resin layer may be formed by applying a liquid spacer material made of a photosensitive resin by, for example, a spin coating method.

  Next, in FIG. 3 (6), corresponding portions of the laminated comb-shaped electrode 20 portion, via-hole portion 81 and dicing portion 12 of the spacer material 41 are removed by patterning by a photolithography method to form the spacer layer 40. .

  Next, in FIG. 3 (7), a cover material 51 made of a photosensitive resin film is laminated on the entire surface of the piezoelectric substrate wafer 11 on which the spacer layer 40 is formed. In the present embodiment, the cover material 51 is made of the same material as the spacer material 41.

  Next, in FIG. 4 (8), the corresponding portions of the laminated via material portion 81 and the dicing portion 12 of the cover material 51 are removed by patterning by a photolithography method to form the cover layer 50. At this time, the patterning is performed so that the opening of the via hole portion 81 and the resin removal region of the dicing portion 12 are not overhanging larger than the opening of the via hole portion 81 and the resin removal region of the dicing portion 12 in the spacer layer 40. With this cover layer 50, the opening of the spacer layer 40 is sealed.

  Next, in FIG. 4 (9), through the opening of the via hole portion 81 and the resin removal portion of the dicing portion 12, a reverse sputtering method using an inert gas such as argon (Ar) or a dry etching method using a chlorine (Cl) gas is used. Then, the protective film 30 is removed by etching using an etching method 31 using a hydrogen fluoride (HF) chemical solution. At this time, since the protective film 30 is etched using the opening of the via hole portion 81 of the spacer layer 40 and the cover layer 50 and the resin removal portion of the dicing portion 12 as the opening portion of the cell alignment mask, a patterning mask dedicated to the protective film is unnecessary. It becomes. Therefore, the cost can be reduced and the production efficiency can be improved.

  Next, in FIG. 4 (10), in order to form the external electrode 80 electrically connected to the internal electrode 70, Ti and Cu or Cr and Cu are formed on the entire surface of the piezoelectric substrate wafer 11 that has undergone the process of FIG. 4 (9). Are continuously sputtered to form a power supply film 82 made of a laminated film. Ti or Cr is a material for ensuring adhesion with a base material.

  Next, in FIG. 4 (11), a photosensitive plating resist material 91 is laminated on the piezoelectric substrate wafer 11 on which the power feeding film 82 is formed.

  Next, in FIG. 4 (12), the plating resist 92 is formed by removing the patterning by a photolithography method so as to leave a portion other than the external electrode 80 of the plating resist material 91.

  Next, in FIG. 4 (13), Ni is first electroplated on the patterning removal portion of the plating resist 92 in order to ensure solder reflow resistance, and then Sn-Ag solder is continuously electroplated. A solder layer 83 is formed to constitute an external electrode 80 composed of a laminate of the power feeding film 82 and the solder layer 83.

Next, in FIG. 5 (14), the plating resist 92 is dissolved and removed with an organic solvent.
Next, in FIG. 5 (15), the exposed portion of the power supply film 82 is removed by etching using the solder layer 83 as a mask.

  Next, in FIG. 5 (16), flux is applied to the solder layer 83 and reflowed to eliminate the recess formed in the via hole portion 81, thereby preventing the generation of solder voids during soldering.

  Finally, in FIG. 5 (17), the piezoelectric substrate wafer 11 is diced by the dicing unit 12 to obtain individual surface acoustic wave devices 100.

  Although not shown, when the laminated spacer material 41 is removed by patterning by a photolithography method in the step of FIG. 3 (6), only the comb electrode 20 and the via hole 81 are removed, and the dicing part 12 is removed. There is also a way to leave. In this method, when the cover material 51 is removed by patterning by the photolithography method in the step of FIG. 4 (8), only the via hole portion 81 is removed and the dicing portion 12 is left. Other steps are the same as those described above.

  FIG. 2 is a cross-sectional view of a surface acoustic wave device 100 according to the second embodiment of the present invention. In the case of this embodiment, the spacer layer 40 and the cover layer 50 of the dicing unit 12 are not removed every time during the process, but are separated together with the piezoelectric substrate wafer 11 in the final dicing process of FIG. A surface acoustic wave device 100 is obtained.

  Therefore, as is clear when the surface acoustic wave device 100 according to the present embodiment shown in FIG. 2 is compared with the surface acoustic wave device 100 according to the first embodiment shown in FIG. 1, the surface according to the present embodiment shown in FIG. In the acoustic wave device 100, the dicing portion 12 that is not covered with the protective film 30 does not exist, and the entire surface of the piezoelectric substrate 10 is covered with the protective film 30.

  The surface acoustic wave device according to the present invention is used as a high frequency filter mounted on a mobile communication device such as a mobile phone.

  Although the surface acoustic wave device has been described in the above embodiment, the present invention is not limited to this, and a mechanical movable part exists in the functional part, for example, a MEMS such as a switch or a gravitational acceleration sensor, a bulk acoustic wave element, or the like. It can be applied to all hollow sealing elements.

1 is a cross-sectional view of a surface acoustic wave device according to a first embodiment of the present invention. It is sectional drawing of the surface acoustic wave device which concerns on 2nd Embodiment of this invention. It is a figure explaining the manufacturing method of the surface acoustic wave device. It is a figure explaining the manufacturing method of the surface acoustic wave device. It is a figure explaining the manufacturing method of the surface acoustic wave device. It is sectional drawing of the surface acoustic wave device proposed conventionally.

Explanation of symbols

  10: Piezoelectric substrate, 11: Piezoelectric substrate wafer, 12: Dicing part, 20: Comb electrode, 21: Comb electrode material, 30: Protective film, 31: Etching method, 40: Spacer layer, 41: Spacer material, 50 : Cover layer, 51: cover material, 60: bump, 70: internal electrode, 80: external electrode, 81: via hole, 82: power supply film, 83: solder layer, 90: void, 91: plating resist material, 92: Plating resist, 100: surface acoustic wave device.

Claims (11)

A functional part having a mechanically movable part, an internal electrode electrically connected to the functional part, and a spacer layer surrounding the functional part and the internal electrode are formed on an insulating substrate,
A hollow having a cover layer on the functional part, the internal electrode and the spacer layer, a gap is formed between the functional part and the cover layer, and an opening of the spacer layer is sealed by the cover layer In the sealing element,
A hollow sealing element, wherein all surfaces of the functional part and the internal electrode are covered with a protective film that does not transmit moisture.   2. The hollow sealing element according to claim 1, wherein the protective film is continuously formed from the surface of the functional part and the internal electrode to the surface of the insulating substrate.   3. The hollow sealing element according to claim 1, wherein the functional part and the internal electrode are made of a material mainly composed of aluminum.   4. The hollow sealing element according to claim 1, wherein the protective film is made of a silicon oxide film, a silicon nitride film, or a diamond-like carbon film. 5.   5. The hollow sealing element according to claim 1, wherein the insulating substrate is a piezoelectric substrate, and the mechanically movable portion is a comb electrode. Forming a set of functional parts having mechanically movable parts and internal electrodes electrically connected to the functional parts as a set on the insulating substrate at a predetermined interval;
Covering the entire upper surface of the insulating substrate on which the functional part and the internal electrode are formed with a protective film that does not transmit moisture;
A photosensitive resin layer is formed on the entire upper surface of the insulating substrate covered with the protective film, and a portion corresponding to the functional portion, the via hole portion corresponding to the connection portion of the internal electrode to the external electrode, and the dicing portion is photolithography method And removing the patterning to form a spacer layer;
Laminating a photosensitive resin film on the entire upper surface of the insulating substrate on which the spacer layer is formed, and forming a cover layer by patterning and removing portions corresponding to the via hole portion and the dicing portion by a photolithography method; ,
Removing the protective film at a position corresponding to the bottom of the via hole portion and the dicing portion using the spacer layer and the cover layer as a mask;
Forming an external electrode by plating from the via hole portion to the external electrode forming portion on the cover layer;
And a step of dicing the dicing section to separate individual devices. Forming a set of functional parts having mechanically movable parts and internal electrodes electrically connected to the functional parts as a set on the insulating substrate at a predetermined interval;
Covering the entire upper surface of the insulating substrate on which the functional part and the internal electrode are formed with a protective film that does not transmit moisture;
A photosensitive resin layer is formed on the entire upper surface of the insulating substrate covered with the protective film, and a portion corresponding to the function part and the via hole part corresponding to the connection part of the internal electrode to the external electrode is patterned by a photolithography method. Removing to form a spacer layer;
Laminating a photosensitive resin film on the entire upper surface of the insulating substrate on which the spacer layer is formed, and forming a cover layer by removing a pattern corresponding to the via hole portion by photolithography,
Removing the protective film at a location corresponding to the bottom of the via hole portion using the spacer layer and the cover layer as a mask;
Forming an external electrode by plating from the via hole portion to the external electrode forming portion on the cover layer;
And a step of dicing the dicing section to separate individual devices.   8. The method of manufacturing a hollow sealing element according to claim 6, wherein the functional part and the internal electrode are made of a material mainly composed of aluminum, and the protective film is a silicon oxide film, a silicon nitride film, or a diamond-like carbon film. A method for producing a hollow sealing element comprising:   9. The method of manufacturing a hollow sealing element according to claim 6, wherein the protective film is removed by using a reverse sputtering method, a dry etching method, or an etching method using a hydrogen fluoride-based chemical. A method for producing a hollow sealing element.   10. The method of manufacturing a hollow sealing element according to claim 6, wherein the insulating substrate is a piezoelectric substrate and the mechanically movable portion is a comb electrode. Manufacturing method.   A mobile communication device equipped with a high-frequency filter, wherein the high-frequency filter is the hollow sealing element according to claim 5.

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