JP2007049261A - Surface acoustic wave element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin surface acoustic wave element, a highly reliable surface acoustic wave element which can be easily packaged and attain low cost, and a manufacturing method thereof. <P>SOLUTION: In the surface acoustic wave element 10, an interdigital transducer (ITD) 80 is formed on the surface of an active surface side of a semiconductor substrate 20. The element is provided with a plurality of insulation layers 41-45 stacked and formed on the surface of the semiconductor substrate 20, a recess 75 drilled on the substantial center of the surface of the insulation layers 41-45, a passivation film 60 formed at least on the bottom surface 76 of the recess 75, a piezoelectric layer 70 formed on the surface of the passivation film 60, the IDT 80 formed on the surface of the piezoelectric layer 70 in the bottom surface 76 of the recess 75, and connection electrode 65, 66 for connection with an external circuit formed on the external periphery of the surface of the surface acoustic wave element 10. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a surface acoustic wave element and a surface acoustic wave element. Specifically, the surface acoustic wave element is provided with a concave portion, and an IDT electrode is formed in the concave portion. It relates to a manufacturing method.

Recently, portable electronic devices typified by mobile phones have become widespread, and high functionality and downsizing have been demanded. Accordingly, the electronic device used in the portable electronic device is naturally required to be downsized.
As a technique for miniaturizing such an electronic device, conventionally, in a functional device unit including a semiconductor element chip, an insulating substrate having a recess formed on the surface, and the substrate is silicon (Si substrate). An insulating film is formed on the bottom surface, side surface, and top surface of the substrate, and a patterned wiring layer is formed in the groove formed by the insulating film so as to continue from the bottom surface of the recess through the side surface to the top surface. In a recess, a semiconductor device chip is flip-chip mounted between the wiring layer and a functional device unit formed by resin-sealing the above-described recess, and a method of manufacturing the functional device unit is known (for example, Patent Document 1).

JP 2002-33410 A (5th and 6th pages, FIG. 2)

  In Patent Document 1, such a functional device unit is formed by mounting a semiconductor element chip in a recess of a substrate having an insulating property and then sealing with a resin. Even if the semiconductor element chip is accommodated in the semiconductor element chip, the thickness of the bottom of the substrate and the thickness of the sealing resin layer are increased with respect to the semiconductor element chip, and the size is increased by the amount of the substrate. End up. Although this semiconductor element chip can be considered by replacing it with the surface acoustic wave element of the present invention to be described later, it is difficult to realize a thin and small surface acoustic wave element for the reasons described above.

  In addition, when mounting this semiconductor element chip on a functional device unit in an electronic device or the like, it must be further connected to an external circuit, and after being flip-mounted on a substrate, the connection process with the external circuit is performed again. As a result, at least two mounting steps are required. Therefore, the manufacturing process becomes longer and the cost reduction is difficult because the semiconductor element chip is mounted on the substrate.

  SUMMARY OF THE INVENTION An object of the present invention is to solve the above-described problems, and to provide a thin surface acoustic wave device, a surface acoustic wave device that can be packaged easily and at a low cost, and has high reliability. It is to provide a manufacturing method thereof.

  The surface acoustic wave device manufacturing method of the present invention is a surface acoustic wave device manufacturing method in which comb-shaped IDT electrodes are formed on the surface of a semiconductor substrate, and a plurality of insulating layers are formed on the active surface side surface of the semiconductor substrate. A step of forming a recess having a depth enough to bury the IDT electrode in a substantially central portion of the insulating layer, and a step of forming a piezoelectric layer on the surface of at least the bottom surface of the recess. A step of forming a comb-tooth-shaped IDT electrode on the surface of the piezoelectric layer formed on the bottom surface of the recess, and a plurality of portions for connecting to an external circuit on the outer peripheral portion of the surface of the surface acoustic wave element Forming a connection electrode.

  Here, although described in detail in the embodiments described later, for example, the semiconductor substrate includes an oscillation circuit, and the plurality of connection electrodes include a power supply electrode, an input signal electrode, an output signal electrode, a ground (GND) electrode, and the like. Is included.

According to this invention, the IDT electrode is formed on the outermost surface of the surface acoustic wave device because the recess having a depth in which the IDT electrode is buried is formed in the substantially central portion of the insulating layer, and the IDT electrode is formed in the recess. Since it does not protrude from the upper surface, a thin surface acoustic wave element can be realized. Further, the outer shape is also within the range of the semiconductor substrate, and there is no projecting thing, and miniaturization can be realized.
Note that the insulating layer can be formed thick in order to form a stacked layer, and it is possible to form a recess that can bury the IDT electrode.

  Such a manufacturing method can be manufactured consistently in a semiconductor manufacturing process in the state of a wafer, and an insulating substrate and a process of mounting on this substrate are not required as in the prior art described above. Thus, the manufacturing process can be shortened and the manufacturing cost can be reduced.

  Further, since the IDT electrode is formed in the recess provided in the insulating layer, the chance of the jig or the like coming into contact with the IDT electrode and damaging the IDT electrode in the subsequent circuit mounting process is reduced, and the reliability is high. A surface acoustic wave device can be provided.

  The method for manufacturing a surface acoustic wave device according to the present invention further includes a step of providing an interlayer wiring layer between the plurality of insulating layers formed on the surface of the semiconductor substrate and around the recess. The connection electrode, the interlayer wiring layer, and the connection electrode provided on the semiconductor substrate are connected by a via hole.

According to such a manufacturing method, an interlayer wiring layer is formed after forming a first insulating layer, a second insulating layer is further laminated, and an interlayer wiring layer is formed. Therefore, a complicated process for forming the interlayer wiring layer is not required.
In addition, a plurality of connection electrodes for connecting to an external circuit, an interlayer wiring layer, and a connection electrode provided on the semiconductor substrate are connected to the external circuit by connecting via the interlayer wiring layer via holes. Therefore, there is an effect that the arrangement of the plurality of connection electrodes and the connection electrodes provided on the semiconductor substrate is not limited, and the electrical connection between the connection electrodes can be easily performed by a generally employed semiconductor manufacturing process. Can be done.

  In the present invention, it is preferable to further include a step of connecting a plurality of connection electrodes for connection to the external circuit and connection electrodes provided on the semiconductor substrate by via holes.

  Since the plurality of connection electrodes for connecting to the external circuit and the connection electrodes provided on the semiconductor substrate are directly connected via via holes without using the above-described interlayer wiring layer, the planar position of the former connection electrode is the latter connection Although it almost coincides with the position of the electrode, since an interlayer wiring layer is not required, the process can be simplified, and the cost can be reduced.

Moreover, according to the manufacturing method of this invention, it is preferable to include the process of carrying out the smooth process of the surface of each layer of the said some insulating layer laminated | stacked.
Here, as the smoothing processing, for example, CMP (Chemical and Mechanical Polishing) or the like can be employed.

In this way, the surface of each insulating layer to be laminated can be finished smoothly, and from this, the smooth surface of all insulating layers including the uppermost surface of the insulating layer laminated in a plurality of layers can be formed. .
Also, if the bottom surface of the recess where the IDT electrode of the recess is formed is an insulating layer that has been smoothed, the IDT electrode can be formed on a smooth surface.

  Moreover, it is preferable that the manufacturing method of the present invention further includes a step of sealing the peripheral portion of the concave portion with a sealing member.

  As described above, since the uppermost layer of the insulating layer is finished smoothly, the adhesion between the uppermost layer of the insulating layer and the sealing member at the peripheral edge of the concave portion is improved, and the concave portion is sealed in which the IDT electrode is disposed. Can be reliably stopped. Therefore, the IDT electrode can be protected from external moisture and dust.

  The surface acoustic wave device according to the present invention is a surface acoustic wave device in which comb-shaped IDT electrodes are formed on the surface of a semiconductor substrate and formed by the above-described manufacturing method, and is laminated on the surface of the semiconductor substrate. A plurality of insulating layers to be formed, a recess formed in a substantially central portion of the insulating layer, a piezoelectric layer formed at least on the surface of the bottom surface of the recess, and a surface of the piezoelectric layer on the bottom surface of the recess And a plurality of connection electrodes for connecting to an external circuit formed on the outer peripheral part of the surface of the surface acoustic wave element.

  According to the present invention, a recess having a depth at which the IDT electrode is buried is formed in a substantially central portion of the semiconductor substrate, and the IDT electrode is formed in the recess. Therefore, the IDT electrode is the outermost surface acoustic wave element. Since it does not protrude from the upper surface, a thin surface acoustic wave element can be realized. Further, the outer shape is also the semiconductor substrate itself, and there is no projecting thing, and miniaturization can be realized.

  Further, such a surface acoustic wave element can be manufactured consistently in a semiconductor manufacturing process in the state of a wafer, and an insulating substrate is not required as in the prior art described above. Enables cost reduction.

  Further, since the IDT electrode is formed in the recess provided in the insulating layer, the chance of the jig or the like coming into contact with the IDT electrode and damaging the IDT electrode in the subsequent circuit mounting process is reduced, and the reliability is high. A surface acoustic wave device can be provided.

  Further, an interlayer wiring layer provided between the plurality of insulating layers formed on the surface of the semiconductor substrate and around the recess is further provided, and the corresponding connection electrode, the interlayer wiring layer, and the semiconductor substrate are provided. It is preferable that the connection electrode provided is connected by a via hole.

  According to such a structure, a plurality of connection electrodes for connecting to an external circuit, an interlayer wiring layer, and a connection electrode provided on the semiconductor substrate are connected to each other via the interlayer wiring layer by a via hole. There is an effect that the arrangement of the plurality of connection electrodes for connecting the connection electrodes and the connection electrodes provided on the semiconductor substrate is not limited.

  The surface acoustic wave device of the present invention includes a plurality of connection electrodes provided on the semiconductor substrate, and a plurality of connection electrodes for connecting an external circuit formed on the outer peripheral portion of the surface of the surface acoustic wave device. Are preferably connected by via holes.

  In this case, since the plurality of connection electrodes for connecting to an external circuit and the connection electrodes provided on the semiconductor substrate are directly connected via the via hole without the interlayer wiring layer described above, the former Although there is a restriction that the planar position of the connection electrode substantially coincides with the position of the latter connection electrode, it does not require an interlayer wiring layer, so that the structure and the process can be simplified, thereby reducing the cost. it can.

Moreover, it is desirable that the recess is sealed with a sealing member.
By sealing the concave portion in which the IDT electrode is disposed with the sealing member in this way, it is possible to prevent moisture and dust from entering the inside, and the IDT electrode is protected and highly reliable. A surface acoustic wave element can be realized. Furthermore, since the uppermost layer of the insulating layer is finished smoothly, the adhesion between the uppermost layer of the insulating layer and the sealing member at the peripheral edge of the concave portion can be improved, and the concave portion can be reliably sealed.

  Furthermore, the sealing member is a circuit board having a wiring pattern, and a plurality of connection electrodes for connecting to an external circuit formed on the outer peripheral portion of the surface of the surface acoustic wave element, and the circuit board It is preferable that the wiring pattern is connected by a connecting member.

  Since the sealing member is configured of the circuit board in this manner, the surface acoustic wave element can be directly connected to the external circuit, and more than the structure in which the sealing member having only the sealing function described above is provided. In addition to being able to reduce the thickness, it is not necessary to provide a space for connection between the surface acoustic wave element and the external circuit, and the circuit board and the like can be downsized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
1 to 3 show a surface acoustic wave device according to Embodiment 1 of the present invention and a method of manufacturing the surface acoustic wave device, FIG. 4 shows a surface acoustic wave device according to Embodiment 2, and FIG. 5 shows an embodiment. 3 shows a mounting method of the surface acoustic wave device according to FIG.
(Embodiment 1)

FIG. 1 is a cross-sectional view schematically showing a surface acoustic wave element according to this embodiment. In FIG. 1, the surface acoustic wave device 10 according to the present embodiment includes a passivation film 30 formed on the active surface side surface of a semiconductor substrate 20 made of silicon (Si) and five layers stacked on the surface of the passivation film 30. The insulating layer 40 is made of silicon oxide (SiO ₂ ), the recess 75 is formed in the substantially central portion of the insulating layer 40, and the bottom surface 76 of the recess 75 extends from the slope 77 to the uppermost layer of the insulating layer 40. A passivation film 60, a piezoelectric layer 70 formed on the surface of the passivation film 60, and a comb-shaped IDT (Interdigital Transducer) electrode 80 formed on the surface of the piezoelectric layer 70 at the bottom surface of the recess 75. It is configured.

  At least an oscillation circuit (not shown) is formed on the semiconductor substrate 20. An opening is formed in the passivation film 30, and connection electrodes 67 and 68 for connecting the oscillation circuit and the IDT electrode 80 are formed in the opening.

  The connection electrodes 67 and 68 are electrode pads made of Al. Although only two electrode pads are shown in FIG. 1, in this embodiment, the connection electrodes 67 and 68 are connected to at least the power supply electrode for driving the oscillation circuit and the IDT electrode 80. A GND, an input signal electrode, and an output signal electrode are formed.

  Insulating layers 41, 42, 43, 44, and 45 are sequentially stacked on the surface of the passivation film 30, and interlayer wiring layers 51 to 58 are formed between these insulating layers. These interlayer wiring layers 51 to 58 are made of Al, and among these, the interlayer wiring layers 51, 53, 55, 57 are ring-shaped along the inner periphery of the insulating layer 40, and the interlayer wiring layers 52, 54 are formed. , 56, 58 are formed in a ring shape between the interlayer wiring layers 51, 53, 55, 57 and the recess 75 and surrounding the periphery of the recess 75.

  Further, the recess 75 has a depth from the uppermost insulating layer 45 to the surface of the lower insulating layer 42 at the bottom surface 76, and the passivation 75 extends over the bottom surface 76, the inclined surface 77, and the surface of the insulating layer 45. A film 60 is formed.

  The passivation film 60 is provided with an opening, and connection electrodes 65 and 66 made of Al for electrically connecting an external circuit (not shown) and the surface acoustic wave element 10 are provided in the opening. Is formed. In FIG. 1, two connection electrodes 65 and 66 are shown, but in the present embodiment, the above-described power supply electrode, GND connected to the IDT electrode 80, an input signal electrode, and an output signal electrode are provided. The

  The connection electrode 65 is electrically connected to the connection electrode 67 on the oscillation circuit side through the interlayer wiring layers 57, 55, 53, 51 through the via hole 85. On the other hand, the connection electrode 66 is connected to the connection electrode 68 on the oscillation circuit side by a via hole 86 through the interlayer wiring layers 58, 56, 54 and 52.

A piezoelectric layer 70 made of zinc oxide (ZnO) is formed over the entire surface of the passivation film 60, and the piezoelectric layer 70 has openings 78 and 79 that are large enough to look into the connection electrodes 65 and 66 described above. It has been established. Although two openings are provided in FIG. 1, they are provided corresponding to the power supply electrode, GND, input signal electrode, and output signal electrode provided as described above.
The piezoelectric layer 70 is not limited to zinc oxide, but may be another material having piezoelectricity. An IDT electrode 80 is formed on the bottom surface 76 in the recess 75 of the piezoelectric layer 70. Since the IDT electrode 80 is made of Al and its planar shape is well known, the description thereof is omitted.

  The IDT electrode 80 is composed of a plurality of comb-shaped electrodes (not shown), and is connected to the oscillation circuit by a via hole (not shown) and an Al wiring layer. These comb-shaped electrodes include, for example, a GND, an input signal electrode, and an output signal electrode, and each is connected to an oscillation circuit. Therefore, the GND, the input signal electrode, and the output signal electrode of the IDT electrode 80 described above are connected to the external circuit formed on the surface of the insulating layer 45, the input signal electrode, and the output signal electrode (in FIG. 1, Are connected to each other by a via hole 85 via the interlayer wiring layers 51, 53, 55 and 57, and a via hole 86 via the interlayer wiring layers 52, 54, 56 and 58. Yes.

In the surface acoustic wave element 10 configured as described above, the upper surface of the recess 75 is sealed with a lid 90 as a sealing member. The lid 90 is appropriately selected from materials such as metal, glass, ceramics, and synthetic resin, and is disposed so as not to overlap the openings 78 and 79 provided in the piezoelectric layer 70 described above. The recess 75 is sealed. The lower surface of the lid 90 and the upper surface of the IDT electrode 80 have a sufficient gap that does not contact.
In addition, when the lid 90 is made of metal, it is preferable to connect the GND to the lid 90.

  In the surface acoustic wave device 10 configured as described above, the IDT electrode 80 is sealed with the lid 90, and the connection electrode 65 and the outer peripheral portion of the surface of the surface acoustic wave device 10, that is, the region outside the lid 90. Reference numeral 66 denotes an opened package.

  Accordingly, in the surface acoustic wave element 10 according to the first embodiment described above, the concave portion 75 having a depth in which the IDT electrode 80 is buried is formed in the substantially central portion of the plane from the uppermost layer of the insulating layer 40. Since 80 is formed, the IDT electrode 80 does not protrude from the uppermost surface of the surface acoustic wave element 10, so that a thin surface acoustic wave element 10 can be realized. Further, the outer shape is also the size of the semiconductor substrate 20 itself, and there is no projecting thing, and miniaturization can be realized.

Further, such a surface acoustic wave element 10 does not require an insulating substrate as in the prior art described above, and can reduce the manufacturing cost.
In addition, since the IDT electrode 80 is formed in the recess 75 provided in the insulating layer 40, the chance of the jig or the like coming into contact with the IDT electrode 80 and being damaged in the subsequent circuit mounting process is reduced. A high surface acoustic wave element 10 can be provided.

  In addition, a plurality of connection electrodes (78 and 79 are illustrated in the figure) for connection with an external circuit, interlayer wiring layers (51 to 58), and connection electrodes provided on the semiconductor substrate 20 (67 and 68 in the figure). Are connected to each other via a selected interlayer wiring layer by via holes (85 and 86 are illustrated in the figure), and a plurality of connection electrodes for connection with an external circuit and the semiconductor substrate 20 are connected to each other. There is an effect that arrangement with a connection electrode provided is not limited.

Further, by sealing the concave portion 75 in which the IDT electrode 80 is disposed in the lid body 90 in this way, it is possible to prevent moisture and dust from entering the concave portion 75, and IDT It is possible to realize the surface acoustic wave element 10 that protects the electrodes 80 from them and has high reliability.
(Method for manufacturing surface acoustic wave element)

Then, the manufacturing method of the surface acoustic wave element of this invention is demonstrated. Here, the surface acoustic wave element 10 having the structure according to the first embodiment will be described as an example.
2 and 3 are cross-sectional views schematically showing a method for manufacturing the surface acoustic wave device 10 according to the present invention.

  2A shows a process of forming the first insulating layer 41 on the semiconductor substrate 20. FIG. At least an oscillation circuit (not shown) is formed on the surface layer of the semiconductor substrate 20. First, a passivation film 30 made of silicon nitride is formed on the surface of the semiconductor substrate 20. On the passivation film 30, connection electrodes 67 and 68 made of Al connected to the oscillation circuit described above by wiring (not shown) are formed.

Next, a first insulating layer 41 made of SiO ₂ is formed on the surface of the passivation film 30, and the surface of the insulating layer 41 is smoothed by a CMP process as a smoothing process. Furthermore, via holes 85 and 86 are formed in the insulating layer 41 in the range of the connection electrodes 67 and 68 described above (hereinafter, via holes formed in other layers are also denoted by reference numerals 85 and 86).
Next, ring-shaped interlayer wiring layers 51 and 52 made of Al and a second insulating layer 42 are formed on the surface of the insulating layer 41.

FIG. 2B shows a process for forming the interlayer wiring layers 51 and 52 and the insulating layer 42. Interlayer wiring layers 51 and 52 made of Al are formed on the surface of the insulating layer 41 by means of sputtering, CVD (Chemical Vapor Deposition) or the like. Interlayer wiring layers 51 and 52 are connected to via holes 85 and 86 formed in the previous step.
Then, a second insulating layer 42 covering the interlayer wiring layers 51 and 52 is formed. The insulating layer 42 is formed with a uniform thickness. However, as shown in the figure, the portion where the interlayer wiring layers 51 and 52 are located is higher than the other portion, and the surface thereof is uneven. Finish with a smooth finish.

FIG. 2C shows a CMP process. By the CMP process, the surface of the second insulating layer 42 is smoothly finished to a uniform thickness. Then, via holes 85 and 86 connected to the interlayer wiring layers 51 and 52 are formed.
In this manner, the third insulating layer 43 to the fifth insulating layer 45 and the interlayer wiring layers 53 to 58 are sequentially stacked between the insulating layers.

FIG. 2D shows a process of forming the insulating layer 45 up to the fifth uppermost layer. Interlayer wiring layers 53 and 54 are formed on the surface of the insulating layer 42 formed in the previous step, and after the insulating layer 43 is formed, smoothing processing is performed by CMP, and the interlayer wiring layers 52, 54, 51 are formed in the via holes 85 and 86. And 53 are connected. Further, after forming the interlayer wiring layers 55 and 56 to form the insulating layer 44, smoothing processing is performed by CMP, and the interlayer wiring layers 56 and 54, 55 and 53 are connected by the via holes 85 and 86. Further, after forming the interlayer wiring layers 57 and 58 to form the insulating layer 45, smoothing processing is performed by CMP, and the interlayer wiring layers 56 and 58, 55 and 57 are connected by the via holes 85 and 86. In this manner, a form in which the insulating layers 41 to 45 and the interlayer wiring layers 51 to 58 are laminated on the semiconductor substrate 20 is formed.
A recess 75 is formed from this form.

FIG. 2E shows a step of forming the recess 75. A resist film or a mask is formed on the surface of the uppermost insulating layer 45, and the recess 75 is formed by dry etching or wet etching. The recess 75 is formed in a trapezoidal shape in which the bottom surface 76 has a planar shape on which the IDT electrode 80 described above can be formed and a cross-sectional shape having a slope 77. The bottom surface 76 is preferably set so as to coincide with the surface of the second insulating layer 42. By doing in this way, the smoothness of the part used as the foundation which forms IDT electrode 80 can be raised.
Then, a passivation film 60 as a protective layer made of silicon nitride is formed on the entire surface of the insulating layer 45 at the periphery of the recess 75 including the recess 75 and the inclined surface 77.

FIG. 3F shows a process of forming a passivation film 60 as a protective film. A passivation film 60 is formed over the surface of the insulating layer 45 at the periphery of the recess 75 including the bottom surface 76 and the inclined surface 77 of the recess 75.
Next, an opening for forming a connection electrode is opened in the passivation film 60, and connection electrodes 65 and 66 are formed.

FIG. 3G shows a process of forming the connection electrodes 65 and 66. In the passivation film 60, openings are formed at positions connectable to the via holes 85 and 86 formed in the previous step, and connection electrodes 65 and 66 made of Al are formed in the openings by means such as vapor deposition and sputtering. To do. The connection electrodes 65 and 66 are connected to the connection electrodes 67 and 68 on the semiconductor substrate 20.
Subsequently, a piezoelectric layer 70 is formed on the surface of the passivation film 60.

FIG. 3H shows a process of forming the piezoelectric layer 70. The piezoelectric layer 70 is formed with a uniform thickness over the entire surface of the passivation film 60 including the recess 75, but openings 78 and 79 are provided to look into the connection electrodes 65 and 66 formed in the previous step. Yes. In this way, the connection electrodes 65 and 66 are opened and can be connected to an external circuit by wire bonding or the like.
Subsequently, the IDT electrode 80 is formed.

  FIG. 3I shows a process of forming the IDT electrode 80. The IDT electrode 80 is formed by interlacing a plurality of comb-shaped electrodes and is formed in the range of the bottom surface 76 of the recess 75. The bottom surface 76 has a smoothness according to the state smoothed by CMP, and the passivation film 60 and the piezoelectric layer 70 are also thin. Therefore, the surface of the piezoelectric layer 70 is also smooth, and the vibration of surface waves is transmitted. Does not affect.

The surface acoustic wave element 10 is completed by the process described above. The lid 90 is fixed and sealed with an adhesive or the like so as to cover the recess 75 of the surface acoustic wave element 10. This state is shown in FIG.
(Modification 1 of manufacturing method)

Next, Modification 1 of the manufacturing method described above will be described. In the first modification, the process after the formation of the insulating layer 40 is changed, and since the parts formed in the individual processes are common, the description will be omitted (see FIG. 1).
First, after forming the insulating layer 40, a passivation film 60 as a protective film is formed on the surface of the uppermost insulating layer 45. At this time, connection electrodes 65 and 66 are formed. Subsequently, a recess 75 including the passivation film 60 is formed.

Next, a passivation film is formed on the inner surface of the recess 75, the piezoelectric layer 70 is formed on the surface of the passivation film in the range of the bottom surface 76 of the recess 75, and then the IDT electrode 80 is formed. Seal.
Note that the passivation film formed on the inner surface of the recess 75 may be formed over the bottom surface 76 and the slope 77 only in the range of the bottom surface 76. Accordingly, the piezoelectric layer 70 may be formed over the entire surface of the passivation film, or only the inner surface of the recess 75 or only the range of the bottom surface 76.
(Modification 2 of manufacturing method)

  Next, another modification 2 of the surface acoustic wave element will be described. The modified example 2 is a modification of the process after the formation of the passivation film 60 of the modified example 1 described above. Since the parts formed in the individual processes are common, the drawings are omitted (FIG. 1). refer). After forming the passivation film 60, an opening for forming the recess 75 and the connection electrode is formed by dry etching or wet etching. At this time, the opening (etching) of the passivation film 60 and the etching of the insulating layer can be performed separately.

Subsequently, a passivation film is formed on the inner surface of the recess 75, and the piezoelectric layer 70 is formed on the surface of the passivation film in the range of the bottom surface 76 of the recess 75. Then, the IDT electrode 80 is formed on the surface of the piezoelectric layer 70, and the connection electrodes 65 and 66 are formed in the opening of the passivation film 60 by film forming means such as vapor deposition and sputtering, and then sealed with the lid 90.
The connection electrodes 65 and 66 can also be formed immediately after the passivation film 60 is formed.

Therefore, according to the method for manufacturing the surface acoustic wave element 10 of the present invention described above, the insulating layers 41 to 45 are stacked, and therefore the recess 75 having a depth sufficient to bury the IDT electrode 80 can be formed. I have to.
In the present embodiment, the insulating layer 40 is composed of five layers. However, the number of layers is not limited to five, and the number of layers may be more or less than five according to the thickness of the IDT electrode 80.

  Further, in the manufacturing method as described above, a large number of surface acoustic wave elements can be manufactured consistently using a semiconductor manufacturing process in the state of a wafer. This eliminates the need for a substrate and a process for mounting on the substrate, and enables shortening of the manufacturing process and reduction of manufacturing cost.

  In addition, since the IDT electrode 80 is formed in the recess 75, the chance of the jig or the like coming into contact with the IDT electrode 80 and damaging the IDT electrode 80 in the subsequent circuit mounting process or the like is reduced, and highly reliable elasticity. A surface acoustic wave device can be provided.

Further, according to such a manufacturing method, an interlayer wiring layer is formed after one insulating layer is formed, and further, an insulating layer is stacked, and interlayer wiring layers 51 to 58 are formed between the insulating layers. A complicated process for forming the wiring layer is not required.
Further, connection electrodes 65 and 66 for connecting to an external circuit, interlayer wiring layers 51 to 58, and connection electrodes 67 and 68 provided on the semiconductor substrate 20 are connected to via holes 85, interlayer wiring layers 51 to 58, respectively. By connecting with 86, there is an effect that the arrangement of the connection electrodes 65 and 66 for connecting to an external circuit and the connection electrodes 67 and 68 provided on the semiconductor substrate is not limited. The electrical connection between the connection electrodes can be easily performed by a manufacturing process.

  Further, in order to finish the surfaces of the laminated insulating layers 41 to 45 smoothly, the formation plane of the interlayer wiring layers 51 to 58 can be formed on a smooth surface. Therefore, since the uppermost surface of the uppermost insulating layer 45 can be formed as a smooth surface, sealing with the lid 90 can be performed reliably.

In addition, even if it employ | adopts the modification 1 and the modification 2 of the manufacturing method mentioned above, there can exist the same effect mentioned above.
(Embodiment 2)

Next, a surface acoustic wave element according to Embodiment 2 of the present invention will be described with reference to the drawings. The second embodiment is characterized in that the interlayer wiring layer is omitted from the structure of the first embodiment described above. Common parts will be described with the same reference numerals.
FIG. 4 is a cross-sectional view schematically showing a surface acoustic wave device according to the second embodiment. 4, in the surface acoustic wave element 10, a passivation film 30 is formed on the surface of a semiconductor substrate 20, and insulating layers 41 to 45 are stacked on the surface. A concave portion 75 is formed at a substantially central portion of the uppermost insulating layer 45, and a passivation film 60 and a piezoelectric layer 70 are laminated from the concave portion 75 to the surface of the insulating layer 45.

  A comb-shaped IDT electrode 80 is formed on the surface of the piezoelectric layer 70 provided on the bottom surface 76 of the recess 75, and the recess 75 is sealed by a lid 90 as a sealing member. .

  Connection electrodes 67 and 68 connected to an oscillation circuit (not shown) are formed in the opening of the passivation film 30, and connection electrodes 65 and 66 formed in the opening of the passivation film 60 formed on the surface of the insulating layer 45 are formed. Are connected by via holes 85 and 86.

  The method for manufacturing the surface acoustic wave device 10 according to the second embodiment is mostly the same as the method of the first embodiment described above, but since there is no interlayer wiring layer, the insulating layers 41 to 45 are sequentially stacked. . At this time, the surface of each insulating layer is finished smoothly by CMP. Then, via holes 85 and 86 penetrating the insulating layer 40 are formed.

  The formation process of the recess 75, the passivation film 60, the piezoelectric layer 70 and the IDT electrode 80, the sealing process by the lid 90 and the order of the processes are the same as in the first embodiment, and thus the description thereof is omitted. Therefore, the connection electrodes 67 and 68 in the lower layer and the connection electrodes 65 and 66 in the upper layer are directly connected by the via holes 85 and 86, respectively.

Therefore, in the surface acoustic wave device 10 according to the second embodiment, the connection electrodes 65 and 66 for connecting to an external circuit and the connection electrodes 67 and 68 provided on the semiconductor substrate 20 are directly connected by the via holes 85 and 86. Therefore, there is a restriction that the planar position of the connection electrodes 65 and 66 substantially coincides with the position of the connection electrodes 67 and 68. However, since an interlayer wiring layer is not required, the structure and the process can be simplified. Therefore, the cost can be reduced.
(Embodiment 3)

Subsequently, Embodiment 3 of the present invention will be described with reference to the drawings. The third embodiment is characterized in that the circuit board 95 is used as the sealing member, whereas the first and second embodiments employ the lid 90 as the sealing member. That is, the surface acoustic wave element 10 is directly mounted on the circuit board 95 constituting the external circuit, and the recess 75 is also sealed.
FIG. 5 is a cross-sectional view schematically showing the structure of the surface acoustic wave element 10 according to this embodiment. In FIG. 5, the surface acoustic wave element 10 exemplifies Embodiment 1 (see FIG. 1) described above, but the surface acoustic wave element according to Embodiment 2 (see FIG. 4) can also be adopted.

  The surface acoustic wave element 10 is fixed to the circuit board 95 with an insulating adhesive, and the recess 75 is sealed with the circuit board 95. In the piezoelectric layer 70 of the surface acoustic wave element 10, openings 78 and 79 for opening connection electrodes 65 and 66 for connection to an external circuit are formed, and the surface acoustic wave element 10 on the circuit board 95 is formed. A wiring pattern (not shown) and electrode lands as connection electrode portions are formed on the surface on the side, and the connection electrodes 65 and 66 and the electrode lands are connected by solder balls or the like as connection members.

  If the connection strength with the solder balls is sufficient, the fixing with the insulating adhesive is not necessary. That is, the surface acoustic wave element 10 is flip-chip mounted on the circuit board 95. Thus, the surface acoustic wave element 10 and the circuit board 95 are structurally and electrically connected.

  Further, if an adhesive or the like is applied to the outer peripheral portion of the portion where the surface acoustic wave element 10 and the circuit board 95 are in contact with each other, the fixing strength can be increased and the sealing performance of the recess 75 can be increased.

  Therefore, according to the third embodiment described above, since the sealing member is configured by the circuit board 95, the surface acoustic wave element 10 can be directly connected to the external circuit, and has only the sealing function described above. The structure can be made thinner than the structure in which the sealing member is provided, and it is not necessary to provide a connection space between the surface acoustic wave element 10 and the external circuit (circuit board 95), and downsizing including the circuit board is possible.

It should be noted that the present invention is not limited to the above-described embodiments, and modifications, improvements, and the like within the scope that can achieve the object of the present invention are included in the present invention.
That is, although the present invention has been illustrated and described with particular reference to particular embodiments, it is not intended to depart from the technical spirit and scope of the invention. Various modifications can be made by those skilled in the art in terms of materials, combinations, other detailed configurations, and processing methods between manufacturing processes.

  Therefore, the description limited to the shape, material, manufacturing process and the like disclosed above is an example for easy understanding of the present invention, and does not limit the present invention. Descriptions in the names of members from which some or all of the limitations such as material, combination, and order of processes are removed are included in the present invention.

For example, in Embodiments 1 to 3 described above, the lid 90 is fixed directly to the surface of the piezoelectric layer 70, but a protective film may be formed on the periphery of the recess 75 of the piezoelectric layer 70.
In addition, although the interlayer wiring layers are disposed between the respective layers of the insulating layer 40, the interlayer wiring layers need not be disposed between all the layers, and the number of layers, the shape, the via holes, and the like can be appropriately selected as necessary. Can be connected.

  In Embodiments 1 and 2 described above, the lid 90 is employed as a sealing member in order to seal the recess 75, but it is also possible to perform resin sealing within the range of the recess 75. In this case, it is preferable that the resin used has a flexibility or thickness that does not affect the propagation of the surface wave.

  Further, in Embodiments 1 to 3 described above, the IDT electrode 80 is formed using the surface of the second insulating layer 42 as a base, but the depth of the recess 75 is such that the lid 90 and the IDT electrode 80 are separated. It can be arbitrarily set in a range where no contact occurs.

  Therefore, according to the above-described first to third embodiments, a thin and small surface acoustic wave element, a highly reliable surface acoustic wave element that can be packaged easily and can be reduced in cost, and a method for manufacturing the same. Can be provided.

1 is a cross-sectional view schematically showing the structure of a surface acoustic wave element according to Embodiment 1 of the present invention. (A)-(e) is sectional drawing which shows typically the manufacturing method of the surface acoustic wave element concerning Embodiment 1 of this invention. (F)-(i) is sectional drawing which shows typically the manufacturing method of the surface acoustic wave element concerning Embodiment 1 of this invention. Sectional drawing which shows typically the structure of the surface acoustic wave element which concerns on Embodiment 2 of this invention. Sectional drawing which shows typically the structure of the surface acoustic wave element which concerns on Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Surface acoustic wave element, 20 ... Semiconductor substrate, 30, 60 ... Passivation film, 40-45 ... Insulating layer, 51-58 ... Interlayer wiring layer, 65-68 ... Connection electrode, 75 ... Recessed part, 76 ... Bottom face of recessed part , 77... Slopes of recesses, 78 and 79... Openings provided in the piezoelectric layer, 80... IDT electrodes, 85 and 86.

Claims (10)

A method for manufacturing a surface acoustic wave device for forming a comb-shaped IDT electrode on the surface of a semiconductor substrate,
Forming a plurality of insulating layers on the active surface side surface of the semiconductor substrate; and
Drilling a recess having a depth in which the IDT electrode is buried in a substantially central portion of the insulating layer;
Forming a piezoelectric layer on at least the bottom surface of the recess;
Forming a comb-shaped IDT electrode on the surface of the piezoelectric layer formed on the bottom surface of the recess;
Forming a plurality of connection electrodes for connection with an external circuit on the outer peripheral portion of the surface of the surface acoustic wave element;
A method for manufacturing a surface acoustic wave device, comprising: In the manufacturing method of the surface acoustic wave element according to claim 1,
The method further includes the step of providing an interlayer wiring layer between the plurality of insulating layers stacked on the surface of the semiconductor substrate and around the recess, and provided on the corresponding connection electrode, the interlayer wiring layer, and the semiconductor substrate. A method of manufacturing a surface acoustic wave device, wherein the connection electrode is connected by a via hole. In the manufacturing method of the surface acoustic wave element according to claim 1,
A method of manufacturing a surface acoustic wave device, further comprising a step of connecting a plurality of connection electrodes for connection to the external circuit and connection electrodes provided on the semiconductor substrate by via holes. In the manufacturing method of the surface acoustic wave element according to any one of claims 1 to 3,
A method of manufacturing a surface acoustic wave device, comprising: smoothing a surface of each of the plurality of insulating layers formed to be stacked. It is a manufacturing method of the surface acoustic wave element according to claim 1,
The method for manufacturing a surface acoustic wave element, further comprising a step of sealing a peripheral portion of the concave portion with a sealing member. A comb-shaped IDT electrode is formed on a surface of a semiconductor substrate, and the surface acoustic wave device is formed by the manufacturing method according to any one of claims 1 to 5,
A plurality of insulating layers stacked on the surface of the semiconductor substrate;
A recess formed in a substantially central portion of the insulating layer;
A piezoelectric layer formed at least on the bottom surface of the recess;
A comb-shaped IDT electrode formed on the surface of the piezoelectric layer at the bottom of the recess;
A plurality of connection electrodes for connecting to an external circuit formed on the outer periphery of the surface of the surface acoustic wave element;
A surface acoustic wave device comprising: The surface acoustic wave device according to claim 6,
An interlayer wiring layer provided between the plurality of insulating layers stacked on the surface of the semiconductor substrate and around the recess is further provided, and is provided on the corresponding connection electrode, the interlayer wiring layer, and the semiconductor substrate. A surface acoustic wave device characterized in that a connection electrode is connected by a via hole. The surface acoustic wave device according to claim 6,
A plurality of connection electrodes provided on the semiconductor substrate and a plurality of connection electrodes for connecting to an external circuit formed on the outer peripheral portion of the surface of the surface acoustic wave element are connected by via holes. A surface acoustic wave device. The surface acoustic wave device according to any one of claims 6 to 8,
The surface acoustic wave element, wherein the recess is sealed with a sealing member. The surface acoustic wave device according to claim 9, wherein
The sealing member is a circuit board having a wiring pattern,
A plurality of connection electrodes for connecting to an external circuit formed on the outer peripheral portion of the surface of the surface acoustic wave element and a wiring pattern of the circuit board are connected by a connection member Surface wave device.

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