JPH07115343A - Surface acoustic wave device and its production - Google Patents

Abstract

PURPOSE:To provide a surface acoustic wave element which can easily be miniaturized and also can improve the stability and the reliability to the soldering heat, etc. CONSTITUTION:A surface acoustic wave element part is substantially sealed airtight onto a substrate 11 containing a surface acoustic wave element directly or via a silicide compound by means of a cover part 13 made of the same material (glass or crystal) as the substrate 11. As both the substrate 11 and the surface acoustic wave element are sealed at a time via the part 13, this element can easily be miniaturized. Furthermore the part 13 is directly adhered onto the substrate 11 without using any adhesive so that the stability is improved to heat. Thus it is possible to suppress the deterioration with age caused by the gas generated from the adhesive and therefore to improve the reliability. The electrode part led out of an interdigital electrode 14 is sealed by low- melting glass.

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 that can be used as a filter or the like that allows only electric signals of a specific frequency to pass therethrough, and a method for manufacturing the same.

[0002]

2. Description of the Related Art With the recent development of mobile communication devices, there is a demand for miniaturization of surface acoustic wave devices constituting them. Here, the surface acoustic wave element is an element that converts an electric signal into a mechanical surface wave and converts only a necessary surface wave component into an electric signal again. A conventional surface acoustic wave device is a substrate in which a comb-shaped electrode for input and output and a pad portion for electrode extraction are formed on a surface of the substrate, and the substrate is individually cut and fixed by an adhesive in a metal or ceramic case.
The structure is such that the substrate is sealed by adhering a metal or ceramic lid to the case after performing wire bonding for drawing out electrodes. 22A, 22B, and 22C show an internal structure, a sectional view, and an external view of a conventional surface mount surface acoustic wave device. In these figures, 221 is a substrate, 222 is a comb-shaped electrode, and 22 is
3 is a pad part, 224 is a ceramic case, 225 is an input / output terminal, 226 is a ground terminal, 227 is a bonding wire, 228 is an adhesive, and 229 is a lid part.

However, in the conventional structure, the width of the adhesive around the case has to be made quite large in order to complete the hermetic sealing, so that even if the size of the substrate becomes small, the size of the substrate as a whole becomes large. Could not be made smaller, and further miniaturization was extremely difficult. In fact, of the surface acoustic wave devices of the ceramic package that have been obtained in the past, even the smallest one is 5 mm × 5 mm × thickness 1.2 mm.
Was the size of.

Further, in the conventional structure, since the adhesive is used for fixing the substrate around the case and the substrate, the adhesive is deteriorated when a high temperature is applied to the case such as soldering, or the adhesive is changed. There is also a problem that gas is generated from the gas, which adversely affects the frequency characteristics of the radio wave filter and deteriorates the long-term stability of the device.

As a method for solving this problem, for example, as proposed in Japanese Patent Laid-Open No. 1-97006,
There is a method of sealing with a glass container to reduce the adverse effect of the adhesive around the case. As another example, there is a method of directly bonding a cap to a substrate as proposed in Japanese Utility Model Laid-Open No. 63-70728.

[0006]

However, the above-mentioned proposal of Japanese Patent Laid-Open No. 1-97006 requires the use of an adhesive to fix the substrate, and cannot solve the problem sufficiently. In addition, other examples of actual development 63
The proposal of Japanese Patent No. 70728 also has a problem that the periphery must be sealed with some kind of adhesive when sealing with a cap. There is also a problem that the width of this portion must be made large in order to maintain airtightness.
Further, it is not possible to suppress the adverse effect of the gas generated from the adhesive existing all around, so that the problem cannot be solved sufficiently.

In order to solve the above-mentioned conventional problems, the present invention facilitates miniaturization of a surface acoustic wave device,
An object of the present invention is to provide a surface acoustic wave device having improved heat stability and reliability and a method for manufacturing the same.

[0008]

In order to achieve the above object, a surface acoustic wave device of the present invention comprises at least a substrate having a surface acoustic wave device and a lid portion made of substantially the same material as the substrate. A surface acoustic wave device provided with the substrate and the lid, wherein the substrate and the lid are self-bonded to each other by an inorganic covalent bond formed by the material itself, and the surface acoustic wave element is substantially hermetically sealed. And

In the above structure, it is preferable that the space between the substrate and the lid is substantially airtightly filled with silicon or a silicon compound. Further, in the above structure, the substrate is preferably at least one substance selected from crystal, lithium niobate, lithium tantalate, and lithium borate.

In the above structure, the silicon compound is preferably silicon oxide or silicon nitride. Further, in the above structure, it is preferable that the coefficient of thermal expansion of the lid is substantially equal to the coefficient of thermal expansion of the substrate.

Further, in the above structure, it is preferable to have a metal film on at least one of the front surface of the lid portion and the back surface of the substrate. Further, in the above structure, the lid is preferably made of at least one substance selected from crystal, glass, lithium niobate, lithium tantalate and lithium borate.

Further, in the above structure, it is preferable that the portion of the extraction electrode between the substrate and the lid is filled with the low melting point glass. Next, in the method of manufacturing a surface acoustic wave device of the present invention, the substrate having the surface acoustic wave element and the surface of the lid portion made of at least one substance selected from the same material as the substrate, glass and crystal are set as follows ( A) and (B)
The surface acoustic wave element portion is substantially hermetically sealed by fixing it by at least one method selected from the above method. (A) A method in which the surface of the substrate and the surface of the lid are cleaned, and then a voltage is applied to the interface to fix them by anodic bonding. (B) The surface of the substrate and the surface of the lid are cleaned and then subjected to hydrophilic treatment. Method of contacting, heat-treating, and fixing the substrate and the lid by direct bonding In the above configuration, the surface of the lid is preferably formed of silicon or a silicon compound.

In the above structure, it is preferable that the surface of the substrate is made of silicon or a silicon compound. In the above structure, it is preferable that the back surface of the substrate is roughened.

Further, in the above structure, it is preferable that the portion of the lead electrode between the substrate and the lid is filled with the low melting point glass. Further, in the above structure, it is preferable to apply a voltage to the interface while heating the substrate and the lid during the anodic bonding.

In the above construction, the heating temperature is 10
It is preferably 0 ° C. or higher. Moreover, in the said structure, it is preferable that heating temperature is 200 degreeC or more. In the above, covalent bond means, for example, when using crystal,
A bond such as -Si-O-Si-.

By using the surface acoustic wave device having the above-mentioned structure, the case surrounding the substrate becomes unnecessary, so that the entire size becomes the size of the substrate, which facilitates miniaturization. Furthermore, since the fixing of the substrate is directly joined,
Since the adhesive interface is physically and chemically stable, the adhesive interface does not change even when high temperature is applied to the case such as soldering, which adversely affects the frequency characteristics of the filter and long-term stability. The problem of worsening is also solved.

[0017]

According to the surface acoustic wave device of the present invention described above, the surface acoustic wave device is provided with at least a substrate having a surface acoustic wave element and a lid portion made of substantially the same material as the substrate. The substrate and the lid portion are self-bonded to each other by an inorganic covalent bond formed by the material itself, and the surface acoustic wave element portion is substantially hermetically sealed, so that the area required for hermetic sealing is reduced. Since it is small, the surface acoustic wave device can be downsized. In addition, since no adhesive is used, it does not change over time and has excellent durability.

Further, according to a preferable construction in which the space between the substrate and the lid is substantially airtightly filled with silicon or a silicon compound, even if particles are present to some degree at the bonding interface, the film at the interface can be used. Will be absorbed,
The range of interface cleanliness is widened. Further, it is not necessary to use a low melting point glass when extracting the electrode.

Further, according to a preferable constitution in which the substrate is at least one substance selected from quartz, lithium niobate, lithium tantalate and lithium borate, direct bonding can be accurately performed, and surface acoustic waves can be accurately performed. It becomes a substrate that can be produced.

Further, according to the preferable constitution in which the silicon compound is silicon oxide or silicon nitride, direct bonding can be accurately performed. Further, according to a preferable configuration in which the coefficient of thermal expansion of the lid portion is substantially equal to the coefficient of thermal expansion of the substrate,
In the case of direct bonding, it is possible to prevent the substrates from cracking or peeling even after heat treatment.

Further, according to a preferable construction in which at least one of the front surface of the lid portion and the back surface of the substrate has a metal film, when the surface acoustic wave device is incorporated in a set,
The surface acoustic wave element can be shielded from electrical noise from the surroundings to stabilize the characteristics.

Further, according to a preferable structure in which the lid portion is at least one substance selected from quartz, glass, lithium niobate, lithium tantalate and lithium borate, the lid material having a thermal expansion coefficient close to that of the substrate. Can be appropriately selected, and in the case of direct bonding, it is possible to prevent the substrate from cracking or peeling even if heat treatment is performed. For example, when the substrate is quartz, the lid may be made of quartz or glass having a coefficient of thermal expansion close to that of quartz. Further, for example, when the substrate is lithium niobate, the lid may be made of lithium niobate or glass having a coefficient of thermal expansion close to that. When the substrate is lithium tantalate, the lid may be made of lithium tantalate or glass having a coefficient of thermal expansion close to that. When the substrate is lithium borate, the lid may be made of lithium borate or glass having a coefficient of thermal expansion close to that.

Further, according to a preferred construction in which the portion of the extraction electrode between the substrate and the lid portion is filled with the low melting point glass, a silicon compound does not exist at the interface between the substrate and the lid portion. In this case, the electrode lead-out portion can be completely hermetically sealed.

Further, when the surface of the lid is made of silicon or a silicon compound, it is possible to efficiently and directly bond the interface between the substrate and the lid via the silicon compound. Further, when the surface of the substrate is made of silicon or a silicon compound, it is possible to efficiently and directly bond the interface between the substrate and the lid via the silicon compound.

When the back surface of the substrate is roughened, a part of the surface acoustic wave generated on the surface of the substrate is reflected on the back surface of the substrate and returns to the surface of the substrate again, so that the characteristics of the surface acoustic wave are increased. Can be prevented from deteriorating.

Further, according to a preferable construction in which the portion of the extraction electrode between the substrate and the lid is filled with the low melting point glass, in the case of the structure in which the silicon compound does not exist at the interface between the substrate and the lid, It is possible to completely perform hermetic sealing in the electrode lead portion.

According to a preferable structure in which a voltage is applied to the interface while heating the substrate and the lid during the anodic bonding, the anodic bonding becomes easy. Specifically, the applied voltage can be lowered or the time for applying the voltage can be shortened.

Further, according to the preferable constitution that the heating temperature is 100 ° C. or higher, preferably 200 ° C. or higher, the bonding strength of the direct bonding can be made sufficiently high.

[0029]

EXAMPLES The present invention will be described in more detail with reference to the following examples. (Example 1) (a), (b), and (c) of FIG.
It is an internal structure, a sectional view, and an external view of a surface acoustic wave element in a present example. In these figures, 11 is a substrate, 12 is an extraction electrode, 13 is a lid, 14 is a comb-shaped electrode, and 15 is a low melting point glass. In this embodiment,
The substrate 11 is 2.4 mm × 2.8 mm × thickness 500.
A μm ST-cut quartz plate, the comb-shaped electrode 14 having a width of 0.1 mm and a length of 1.1 mm at the center of the surface, and the extraction electrode 12 for grounding and inputting / outputting around the comb-shaped electrode 14. It was formed by a vapor deposition film of chromium and gold. Further, the lid 13 has a size of 1.4 mm × 2.8 mm × thickness 5
It is a crystal plate with ST cut of 00 μm. In the case of the present embodiment, the ST-cut crystal plate of the lid 13 is used in such a direction that the thermal expansion coefficient thereof is substantially the same as that of the ST-cut crystal plate of the substrate 11, and the substrate 11 is directly bonded. The thermal stress is applied to the surface acoustic wave element so that the resonance characteristics of the surface acoustic wave element do not deteriorate. Furthermore, the central portion of the lid portion 13 was etched to a depth of 0.4 mm × 1.8 mm × depth of 1 μm, and the portion of the substrate corresponding to the extraction electrode 12 was hollowed to a depth of 1 μm. Accordingly, even when the substrate 11 is directly bonded to the substrate 11,
The lid portion 13 does not touch the comb-shaped electrode 14 and the lead-out electrode 12 formed above. The substrate 11 and the lid portion 13 are directly joined after cleaning the surfaces thereof, and the portion of the extraction electrode 12 is finally sealed with the low melting point glass 15. The comb-shaped electrode 14 is substantially hermetically sealed by the lid 13.

In order to obtain a concretely directly bonded interface, two methods were used here. As the first method,
This was performed by a method of utilizing hydrophilic groups on the surface of a substrate, in which a silicon substrate, a crystal plate, or the like, which had been subjected to polishing, washing, and hydrophilic group formation treatment, was contacted in a clean atmosphere and heat treatment was performed to obtain firm fixation. In this embodiment, the method using the first method is mainly described. The bonding strength of the direct bonding interface obtained by the above method is several tens of kgw / cm ² even in the initial stage of contact after the hydrophilic group formation treatment.
Although the value is about the same, the value increases to several hundred kgw / cm ² or more by the heat treatment. Here,
The bond strength at the joined interface is defined as "the limit value of the tensile stress at which the interface separates when the tensile stress is applied in the direction perpendicular to the interface".

Specifically, such a bond is formed as follows. After the hydrophilic groups are formed on the substrates to be bonded, the non-adhesive substrates are present between the hydrophilic groups formed on the surface and the non-adhesive surface at the initial stage of merely bringing the substrates into contact with each other. It is covalently bonded through hydrogen bonds with water molecules. For example, in FIG.
(B) and 23 (c) show the steps of the first direct joining method. In these figures, 231 and 232 are Si
The substrate. FIG. 23A shows an initial stage in which the Si plates are simply brought into contact with each other, and the non-adhesive Si plates are bonded to each other by hydrogen bonding between hydrophilic groups on the surfaces and water molecules existing between the non-adhesive surfaces. Are connected through. By performing heat treatment from this state, water molecules existing at the interface are removed from the interface, and the bond via the water molecule gradually changes to a strong covalent bond between the crystal constituent atoms (FIG. 23).
(C)).

FIG. 23B shows the bonded state of the Si plates 231 and 232 after the heat treatment at 200 ° C.
7 angstroms (70 nm) in 3 (a)
(L ₁ ). The distance between the Si plates 231 and 232 is 3.5 angstrom (35 nm) due to this heat treatment.
It became (L ₂ ). In addition, by heat treatment at 700 ° C. or higher, water molecules existing at the interface are removed from the interface (FIG. 23).
(C)), the distance between the Si plates 231 and 232 was 1.6 angstrom (16 nm) (L ₃ ).

As described above, by performing the heat treatment, the water molecules existing at the interface are removed from the interface, and the bond through the water molecule gradually changes into a strong covalent bond between the crystal-constituting atoms. Therefore, in fixing using direct bonding, since the bonding strength is high and the bonding is done at the atomic level, the cross-sectional area required to maintain airtightness may be small, so the size of the case is extremely small. It can be reduced. Further, since no organic adhesive is used, it is resistant to heat treatment, vibration, etc., and unnecessary gas is not emitted.

As a second concrete method for obtaining the directly bonded interface, a silicon substrate or a crystal plate which has been subjected to polishing and cleaning treatment is brought into direct contact, and a voltage is applied while heating,
The method of fixing by the electrostatic attraction (anodic bonding) was used. Also by this method, a crystal device having the same structure as that of the present example, which has a bonding interface directly bonded as in the first method, was obtained. Also in this case, since the adhesive strength is high as in the first method, the size of the case can be made extremely small, and since no adhesive is used, it is resistant to heat treatment, vibration, etc. No gas is released.

In the present invention, the low melting point glass is used for the lead-out portion of the electrode, but the surface area thereof is very small and the influence thereof can be ignored. (Example 2) (a), (b), and (c) of FIG.
It is an internal structure, a sectional view, and an external view of a surface acoustic wave element in a present example. In these figures, 21 is a substrate, 22 is an extraction electrode, 23 is a lid, 24 is a comb-shaped electrode, and 25 is a low melting point glass. In this embodiment,
The substrate 21 is 2.4 mm × 2.8 mm × thickness 500.
It is a crystal plate that is ST-cut by μm, and the comb-shaped electrode 24 having a width of 0.1 mm and a length of 1.1 mm is provided at the center of the surface thereof, and the extraction electrode 22 for grounding and input / output is provided around the comb-shaped electrode 24. It was formed by a vapor deposition film of chromium and gold. Further, the lid portion 23 has a thickness of 1.4 mm × 2.8 mm × thickness 5
It is a glass plate of 00 μm. In the case of the present embodiment, the glass plate of the lid portion 23 has a coefficient of thermal expansion substantially equal to that of the ST-cut crystal plate of the substrate 21, and thermal stress is applied to the substrate 21 after being directly bonded to the elastic surface. The resonance characteristics of the wave element are prevented from deteriorating. Further, the central portion of the lid portion 23 is etched by 0.4 mm × 1.8.
It was hollowed out to mm x depth 1 μm. As a result, even when directly bonded to the substrate 21, the lid 23 does not touch the comb-shaped electrode 24 and the extraction electrode 22 formed on the substrate 21. The substrate 21 and the lid portion 23 are directly bonded after cleaning the surfaces thereof, and the portion of the extraction electrode 22 is finally sealed with the low melting point glass 25. The comb-shaped electrode 24 is substantially hermetically sealed by the lid portion 23.

(Embodiment 3) FIGS. 3 (a), 3 (b) and 3 (c) are an internal structure, a sectional view and an external view of a surface acoustic wave device according to this embodiment. In these figures, 31 is a substrate, 32 is an extraction electrode, 33 is a lid, 34
The comb-shaped electrode and 35 are low melting glass. In the present embodiment, the substrate 31 has a size of 2.4 mm × 2.8 mm ×
A Y-cut lithium niobate substrate having a thickness of 500 μm, with a width of 0.1 mm and a length of 1.1 m at the center of its surface.
m of the comb-shaped electrode 34, and the lead-out electrode 32 for grounding and inputting / outputting were formed on the periphery thereof by a vapor deposition film of chromium and gold. The lid 33 has a size of 1.4 mm ×
It is an AT-cut quartz plate having a thickness of 2.8 mm and a thickness of 500 μm. In the case of the present embodiment, the AT-cut quartz plate of the lid portion 33 is used in such a direction that the thermal expansion coefficient of the substrate 31 is substantially the same as that of the Y-cut lithium niobate substrate of the substrate 31, and is directly bonded to the substrate 31. The thermal stress is applied so as not to deteriorate the resonance characteristics of the surface acoustic wave element. further,
The central portion of the lid 33 is 0.4 mm by etching.
It was hollowed out in a shape of × 1.8 mm × depth of 1 μm, and a portion corresponding to the extraction electrode 32 was hollowed out in a shape of 1 μm in depth. As a result, even when directly bonded to the substrate 31, the lid portion 33 does not touch the comb-shaped electrode 34 and the extraction electrode 32 formed on the substrate 31. The substrate 31 and the lid 33 are directly joined after cleaning their surfaces, and the portion of the extraction electrode 32 is finally sealed by the low melting point glass 35. Comb-shaped electrode 34
Are substantially hermetically sealed by the lid 33.

(Embodiment 4) FIGS. 4A, 4B, and 4C are an internal structure, a sectional view, and an external view of a surface acoustic wave device according to this embodiment. In these figures, 41 is a substrate, 42 is an extraction electrode, 43 is a lid, 44
Comb-shaped electrodes, and 45 is a low melting point glass. In this embodiment, the substrate 41 has a size of 2.4 mm × 2.8 mm ×
A Y-cut lithium tantalate substrate with a thickness of 500 μm, with a width of 0.1 mm and a length of 1.1 m at the center of its surface.
m of the comb-shaped electrode 44 and the lead-out electrode 42 for grounding and inputting / outputting were formed around the comb-shaped electrode 44 by a vapor deposition film of chromium and gold. The lid 43 has a size of 1.4 mm ×
It is an X-cut crystal plate having a thickness of 2.8 mm and a thickness of 500 μm.
In the case of the present embodiment, the X-cut crystal plate of the lid 43 is used in such a direction that the coefficient of thermal expansion of the Y-cut lithium tantalate substrate of the substrate 41 is substantially the same, and is directly bonded to the substrate 41. The thermal stress is applied so as not to deteriorate the resonance characteristics of the surface acoustic wave element. Further, the central portion of the lid 43 is 0.4 mm × by etching.
It was hollowed out in a shape of 1.8 mm × depth of 1 μm, and a portion corresponding to the extraction electrode 42 was hollowed out in a shape of 1 μm in depth. Thus, even when the substrate 41 is directly bonded, the lid portion 43 does not touch the comb-shaped electrode 44 and the extraction electrode 42 formed on the substrate 41. The substrate 41 and the lid 43 are directly bonded after cleaning the surfaces thereof, and the portion of the extraction electrode 42 is finally sealed by the low melting point glass 45. The comb-shaped electrode 44 is
The lid 43 substantially hermetically seals.

(Embodiment 5) FIGS. 5A, 5B, and 5C are an internal structure, a sectional view, and an external view of a surface acoustic wave device according to this embodiment. In these figures, 51 is a substrate, 52 is an extraction electrode, 53 is a lid, 54
The comb-shaped electrode and 55 are low melting glass. In the present embodiment, the substrate 51 has a size of 2.4 mm × 2.8 mm ×
A Y-cut lithium niobate substrate having a thickness of 500 μm, with a width of 0.1 mm and a length of 1.1 m at the center of its surface.
m of the comb-shaped electrode 54, and the lead-out electrode 52 for grounding and input / output were formed on the periphery of the comb-shaped electrode 54 by a vapor deposition film of chromium and gold. Further, the lid portion 53 is 1.4 mm ×
It is a lithium niobate substrate having a thickness of 2.8 mm and a thickness of 500 μm. In the case of the present embodiment, the lithium niobate substrate of the lid portion 53 is used in such a direction that its coefficient of thermal expansion is substantially the same as that of the Y-cut lithium niobate substrate of the substrate 51.
The substrate 51 is prevented from being deteriorated in the resonance characteristics of the surface acoustic wave element by being applied with thermal stress after the direct bonding. Further, the central portion of the lid portion 53 is etched by etching.
It was hollowed out in a shape of 4 mm × 1.8 mm × depth of 1 μm, and a portion corresponding to the extraction electrode 52 was hollowed out in a shape of 1 μm in depth. Accordingly, even when the substrate 53 is directly bonded, the lid portion 53 does not touch the comb-shaped electrode 54 and the extraction electrode 52 formed on the substrate 51. The substrate 51 and the lid 53 are
The surfaces are cleaned and then directly bonded, and the part of the extraction electrode 52 is finally sealed by the low melting point glass 55. Therefore, the comb-shaped electrode 54 on the substrate 51 is covered by the lid 53. It is substantially hermetically sealed.

(Embodiment 6) FIGS. 6A, 6B, and 6C are an internal structure, a sectional view, and an external view of a surface acoustic wave device according to this embodiment. In these figures, 61 is a substrate, 62 is an extraction electrode, 63 is a lid, and 64
The comb-shaped electrode and 65 are low melting point glass. In the present embodiment, the substrate 61 has a size of 2.4 mm × 2.8 mm ×
A Y-cut lithium tantalate substrate with a thickness of 500 μm, with a width of 0.1 mm and a length of 1.1 m at the center of its surface.
m of the comb-shaped electrode 64, and the lead-out electrode 62 for grounding and inputting / outputting were formed around the comb-shaped electrode 64 by a vapor deposition film of chromium and gold. The lid 63 has a size of 1.4 mm ×
It is a lithium tantalate substrate having a thickness of 2.8 mm and a thickness of 500 μm. In the case of the present embodiment, the lithium tantalate substrate of the lid portion 63 is used in such a direction that the coefficient of thermal expansion thereof is substantially the same as that of the Y-cut lithium tantalate substrate of the substrate 61, and is directly bonded to the substrate 61. The thermal stress is applied so as not to deteriorate the resonance characteristics of the surface acoustic wave element. Further, the central portion of the lid portion 63 is etched into a shape of 0.4 mm × 1.8 mm × depth of 1 μm, and the portion corresponding to the extraction electrode 62 is cut to a depth of 1 μm.
Hollowed out in the shape of m. As a result, even when directly bonded to the substrate 61, the lid 63 does not touch the comb-shaped electrode 64 and the extraction electrode 62 formed on the substrate 61. The substrate 61 and the lid 63
Means that after the surfaces thereof are cleaned, they are directly bonded to each other, and further, the portion of the extraction electrode 62 is finally sealed by the low melting point glass 65, so that the comb-shaped electrode 64 on the substrate 61 is The portion 63 is hermetically sealed.

(Embodiment 7) FIGS. 7A, 7B, and 7C are an internal structure, a sectional view, and an external view of a surface acoustic wave device according to this embodiment. In these figures, 71 is a substrate, 72 is an extraction electrode, 73 is a lid, and 74
Comb-shaped electrodes and 75 are low melting glass. In this embodiment, the substrate 71 has a size of 2.4 mm × 2.8 mm ×
A Y-cut lithium niobate substrate having a thickness of 500 μm, with a width of 0.1 mm and a length of 1.1 m at the center of its surface.
m of the comb-shaped electrode 74, and the lead-out electrode 72 for grounding and input / output were formed on the periphery thereof by a vapor deposition film of chromium and gold. Further, the lid portion 73 is 1.4 mm ×
It is a glass plate having a thickness of 2.8 mm and a thickness of 500 μm. In addition,
In the case of the present embodiment, the glass plate of the lid portion 73 has a coefficient of thermal expansion substantially equal to that of the Y-cut lithium niobate substrate of the substrate 71, and thermal stress is applied to the substrate 71 after direct bonding to provide an elastic surface. The resonance characteristics of the wave element are prevented from deteriorating. Further, the central portion of the lid portion 73 was hollowed out into a shape of 0.4 mm × 1.8 mm × depth of 1 μm by etching, and the portion corresponding to the extraction electrode 72 was hollowed out into a shape of 1 μm in depth. Accordingly, even when the substrate 71 is directly bonded, the comb-shaped electrode 74 and the extraction electrode 72 formed on the substrate 71.
The lid portion 73 does not touch. The substrate 71 and the lid portion 73 are directly joined after cleaning the surfaces thereof, and the portion of the extraction electrode 72 is finally sealed by the low melting point glass 75. The comb-shaped electrode 74 is substantially hermetically sealed by the lid portion 73.

(Embodiment 8) FIGS. 8A, 8B, and 8C are an internal structure, a sectional view, and an external view of a surface acoustic wave device according to this embodiment. In these figures, 81 is a substrate, 82 is an extraction electrode, 83 is a lid, and 84
Comb-shaped electrodes, and 85 is a low melting point glass. In this embodiment, the substrate 81 has a size of 2.4 mm × 2.8 mm ×
The substrate is a lithium tantalate substrate having a thickness of 500 μm, the comb-shaped electrode 84 having a width of 0.1 mm and a length of 1.1 mm is provided at the center of the surface, and the extraction electrode 82 for grounding and input / output is provided around the comb-shaped electrode 84. It was formed by a vapor deposition film of chromium and gold. The lid 83 has a size of 1.4 mm x 2.8 mm.
A glass plate having a thickness of 500 μm. In the case of the present embodiment, the glass plate of the lid portion 83 has a coefficient of thermal expansion substantially equal to that of the lithium tantalate substrate of the substrate 81,
The substrate 81 is prevented from being deteriorated in the resonance characteristics of the surface acoustic wave element by being applied with thermal stress after the direct bonding. Further, the central portion of the lid portion 83 is etched by etching.
It was hollowed out in a shape of 4 mm × 1.8 mm × depth of 1 μm, and a portion corresponding to the extraction electrode 82 was hollowed out in a shape of 1 μm in depth. Accordingly, even when the substrate 81 is directly bonded, the lid portion 83 does not touch the comb-shaped electrode 84 and the extraction electrode 82 formed on the substrate 81. The substrate 81 and the lid 83 are
The surfaces are cleaned and then directly bonded, and the portion of the extraction electrode 82 is finally sealed by the low-melting glass 85, so that the comb-shaped electrode 84 on the substrate 81 is covered by the lid portion 83. It is substantially hermetically sealed.

(Embodiment 9) FIGS. 9A, 9B, and 9C are an internal structure, a sectional view, and an external view of a surface acoustic wave device according to this embodiment. In these figures, 91 is a substrate, 92 is an extraction electrode, 93 is a lid, and 94 is
The comb-shaped electrode and 95 are silicon compound films. In this embodiment, the substrate 91 has a size of 2.4 mm × 2.8 mm ×
It is an ST-cut quartz plate having a thickness of 500 μm, the comb-shaped electrode 94 having a width of 0.1 mm and a length of 1.1 mm is provided at the center of the surface thereof, and the extraction electrode 92 for grounding and input / output is provided around the comb-shaped electrode 94. It was formed by a vapor deposition film of chromium and gold.
Further, a silicon oxide film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 94 that is directly joined to the lid portion 93 (hatched portion in FIG. 9B), and the surface thereof is slightly polished. Then, the silicon compound film 95 is formed by flattening to a thickness of about 1 μm. This prevents the lid 93 from coming into contact with the comb-shaped electrode 94 formed on the substrate 91 even when directly bonded to the substrate 91.
The lid 93 is an ST-cut quartz plate having a size of 2.8 mm × 1.4 mm × thickness of 500 μm. In the case of the present embodiment, the ST-cut crystal plate of the lid 93 is used in such a direction that the thermal expansion coefficient thereof is substantially the same as that of the ST-cut crystal plate of the substrate 91. The stress is applied so that the resonance characteristics of the surface acoustic wave element do not deteriorate. Since the substrate 91 and the lid portion 93 are directly bonded via the silicon compound film 95, the comb-shaped electrode 94 on the substrate 91 is substantially hermetically sealed by the lid portion 93. .

(Example 10) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 101 is a substrate, 102 is an extraction electrode, 103 is a lid, 104 is a comb-shaped electrode, and 105 is a silicon compound film. In this embodiment, the substrate 101 has a length of 2.4 m.
m × 2.8 mm × 500 μm thick ST-cut quartz plate, 0.1 mm wide and 1.1 mm long at the center of the surface.
The comb-shaped electrode 104 of mm and the lead-out electrode 102 for grounding and inputting / outputting were formed on the periphery of the comb-shaped electrode 104 by a vapor deposition film of chromium and gold. Further, a portion of the peripheral portion of the comb-shaped electrode 104 that is directly joined to the lid portion 103 (see FIG. 10).
A silicon nitride film having a thickness of 2 μm was formed in the hatched portion of (b), and the surface thereof was slightly polished to a thickness of about 1 μm for flattening to form the silicon compound film 105.
Accordingly, even when the substrate 101 is directly joined,
The comb-shaped electrode 10 formed on the substrate 101.
The lid 103 does not touch the surface 4. The lid 103 has a thickness of 2.8 mm × 1.4 mm × a thickness of 500 μm.
This is an ST cut crystal plate. In the case of the present embodiment, the ST-cut crystal plate of the lid 103 is used in such a direction that the thermal expansion coefficient thereof is substantially the same as that of the ST-cut crystal plate of the substrate 101. The stress is applied so that the resonance characteristics of the surface acoustic wave element do not deteriorate. Since the substrate 101 and the lid 103 are directly bonded to each other via the silicon compound film 105, the comb-shaped electrode 104 on the substrate 101 is not covered by the lid 103.
Is substantially hermetically sealed by.

(Embodiment 11) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 111 is a substrate, 112 is an extraction electrode, 113 is a lid, 114 is a comb-shaped electrode, and 115 is a silicon compound film. In this embodiment, the substrate 111 has a length of 2.4 m.
m-2.8 mm × 500 μm-thick Y-cut lithium niobate substrate with a width of 0.1 m at the center of its surface
The comb-shaped electrode 114 having a length of m and a length of 1.1 mm and the lead-out electrode 112 for grounding and inputting / outputting were formed around the comb-shaped electrode 114 by a vapor deposition film of chromium and gold. Further, a silicon oxide film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 114 that is directly joined to the lid portion 113 (hatched portion in FIG. 11B), and the surface thereof is slightly polished. To a thickness of about 1 μm for planarization, and the silicon compound film 115
Was formed. This prevents the lid 113 from touching the comb-shaped electrode 114 formed on the substrate 111 even when directly bonded to the substrate 111.
The lid 113 is a Y-cut lithium niobate substrate of 2.8 mm × 1.4 mm × thickness of 500 μm.
In the case of the present embodiment, the Y-cut lithium niobate substrate of the lid 113 is used in such a direction that the coefficient of thermal expansion thereof is substantially the same as that of the Y-cut lithium niobate substrate of the substrate 111. It is so arranged that thermal stress is not applied to the substrate 111 and the resonance characteristics of the surface acoustic wave element are not deteriorated. Since the substrate 111 and the lid 113 are directly bonded via the silicon compound film 115, the comb-shaped electrode 114 on the substrate 111 is substantially hermetically sealed by the lid 113. .

(Embodiment 12) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 121 is a substrate, 122 is an extraction electrode, 123 is a lid, 124 is a comb electrode, and 125 is a silicon compound film. In this embodiment, the substrate 121 has a length of 2.4 m.
m-2.8 mm × 500 μm-thick Y-cut lithium niobate substrate with a width of 0.1 m at the center of its surface
The comb-shaped electrode 124 having a length of m and a length of 1.1 mm and the lead-out electrode 122 for grounding and inputting / outputting were formed on the periphery thereof by a vapor deposition film of chromium and gold. Further, a silicon nitride film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 124 which is directly bonded to the lid portion 123 (hatched portion in FIG. 12B), and the surface thereof is slightly polished. To a thickness of about 1 μm for planarization.
Was formed. Accordingly, even when the substrate 121 is directly joined, the lid 123 does not touch the comb-shaped electrode 124 formed on the substrate 121.
The lid 123 is a Y-cut lithium niobate substrate of 2.8 mm × 1.4 mm × thickness 500 μm.
In the case of the present embodiment, the Y-cut lithium niobate of the lid 123 is used in a direction such that the coefficient of thermal expansion of the Y-cut lithium niobate substrate of the substrate 121 is substantially the same, and after the direct bonding, the Thermal stress is applied to the substrate 121 so that the resonance characteristics of the surface acoustic wave element do not deteriorate. Since the substrate 121 and the lid 123 are directly bonded via the silicon compound film 125, the substrate 1
The comb-shaped electrode 124 on 21 is substantially hermetically sealed by the lid 123.

(Example 13) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 131 is a substrate, 132 is an extraction electrode, 133 is a lid, 134 is a comb-shaped electrode, and 135 is a silicon compound film. In this embodiment, the substrate 131 has a length of 2.4 m.
m-2.8 mm × 500 μm-thick Y-cut lithium tantalate substrate, the center of the surface of which has a width of 0.1 mm and a length of 1.1 mm of the comb-shaped electrode 134,
And the extraction electrode 1 for input / output around and around
32 was formed by a vapor deposition film of chromium and gold. Further, a silicon oxide film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 134 that is directly joined to the lid 133 (hatched portion in FIG. 13B), and the surface thereof is slightly polished. Then, the silicon compound film 135 is formed by flattening to a thickness of about 1 μm. Accordingly, even when the substrate 131 is directly bonded, the lid 133 does not touch the comb-shaped electrode 134 formed on the substrate 131. In addition, the lid 133 is 2.8 mm × 1.4.
It is a Y-cut lithium tantalate substrate of mm × thickness 500 μm. In the case of the present embodiment, Y of the lid 133 is
The cut lithium tantalate is used in a direction in which the coefficient of thermal expansion of the substrate 131 is substantially the same as that of the Y-cut lithium tantalate substrate, and thermal stress is applied to the substrate 131 after the direct bonding and the resonance characteristics of the surface acoustic wave device. To prevent it from deteriorating. Since the substrate 131 and the lid 133 are directly bonded via the silicon compound film 135, the comb-shaped electrode 134 on the substrate 131 is substantially hermetically sealed by the lid 133. .

Example 14 (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 141 is a substrate, 142 is an extraction electrode, 143 is a lid, 144 is a comb-shaped electrode, and 145 is a silicon compound film. In this embodiment, the substrate 141 has a length of 2.4 m.
It is a Y-cut lithium tantalate substrate of m × 2.8 mm × thickness 500 μm, and a width of 0.1 m at the center of its surface.
The comb-shaped electrode 144 having a length of m and a length of 1.1 mm and the lead-out electrode 142 for grounding and inputting / outputting were formed on the periphery thereof by a vapor deposition film of chromium and gold. Further, a silicon nitride film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 144 directly joined to the lid portion 143 (hatched portion in FIG. 14B), and the surface thereof is slightly polished. To a thickness of about 1 μm for planarization, and the silicon compound film 145
Was formed. Accordingly, even when the substrate 141 is directly bonded, the lid 143 does not touch the comb-shaped electrode 144 formed on the substrate 141.
The lid portion 143 is a Y-cut lithium tantalate substrate having a thickness of 2.8 mm × 1.4 mm × a thickness of 500 μm. In the case of the present embodiment, the Y-cut lithium tantalate substrate of the lid 143 is used in a direction in which the coefficient of thermal expansion of the Y-cut lithium tantalate substrate of the substrate 141 is substantially the same as that of the substrate 141. The substrate 141
Thermal stress is applied to the surface acoustic wave element to prevent the resonance characteristics of the surface acoustic wave element from deteriorating. The substrate 141 and the lid 143
Since it is directly bonded via the silicon compound film 145, the comb-shaped electrode 144 on the substrate 141 is substantially hermetically sealed by the lid 143.

(Example 15) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 151 is a substrate, 152 is an extraction electrode, 153 is a lid, 154 is a comb electrode, and 155 is a silicon compound film. In this embodiment, the substrate 151 has a length of 2.4 m.
m-2.8 mm × 500 μm-thick Y-cut lithium niobate substrate with a width of 0.1 m at the center of its surface
The comb-shaped electrode 154 having a length of m and a length of 1.1 mm and the lead-out electrode 152 for grounding and inputting / outputting were formed on the periphery thereof by a vapor deposition film of chromium and gold. Further, a silicon oxide film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 154 that is directly bonded to the lid portion 153 (hatched portion in FIG. 15B), and the surface thereof is slightly polished. To a thickness of about 1 μm for planarization.
Was formed. Accordingly, even when the substrate 151 is directly bonded, the lid 153 does not touch the comb-shaped electrode 154 formed on the substrate 151.
The lid portion 153 is a glass plate having a size of 2.8 mm × 1.4 mm × a thickness of 500 μm. In the case of the present embodiment, the glass plate of the lid portion 153 is the Y of the substrate 151.
The coefficient of thermal expansion is substantially the same as that of the cut lithium niobate substrate, and the substrate 151 is prevented from being deteriorated in the resonance characteristics of the surface acoustic wave element by being subjected to thermal stress after being directly bonded. Since the substrate 151 and the lid 153 are directly bonded via the silicon compound film 155, the comb-shaped electrode 154 on the substrate 151 is substantially hermetically sealed by the lid 153. .

(Example 16) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 161 is a substrate, 162 is an extraction electrode, 163 is a lid, 164 is a comb-shaped electrode, and 165 is a silicon compound film. In this embodiment, the substrate 161 has a length of 2.4 m.
m-2.8 mm × 500 μm-thick Y-cut lithium niobate substrate with a width of 0.1 m at the center of its surface
The comb-shaped electrode 164 having a length of m and a length of 1.1 mm and the lead-out electrode 162 for grounding and inputting / outputting were formed on the periphery thereof by a vapor deposition film of chromium and gold. Further, a silicon nitride film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 164 that is directly bonded to the lid portion 163 (hatched portion in FIG. 16B), and the surface thereof is slightly polished. To a thickness of about 1 μm for planarization, and the silicon compound film 165 is formed.
Was formed. Accordingly, even when the substrate 161 is directly bonded, the lid 163 does not touch the comb-shaped electrode 164 formed on the substrate 161.
The lid portion 163 is a glass plate having a size of 2.8 mm × 1.4 mm × a thickness of 500 μm. In the case of the present embodiment, the glass plate of the lid portion 163 is the Y of the substrate 161.
The coefficient of thermal expansion of the cut lithium niobate substrate is substantially the same as that of the cut lithium niobate substrate so that thermal stress is not applied to the substrate 161 after the direct bonding and the resonance characteristics of the surface acoustic wave element are not deteriorated. Since the substrate 161 and the lid 163 are directly bonded via the silicon compound film 165, the comb-shaped electrode 164 on the substrate 161 is substantially hermetically sealed by the lid 163. .

(Embodiment 17) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 171 is a substrate, 172 is an extraction electrode, 173 is a lid, 174 is a comb electrode, and 175 is a silicon compound film. In this embodiment, the substrate 171 has a length of 2.4 m.
It is a Y-cut lithium tantalate substrate of m × 2.8 mm × thickness 500 μm, and a width of 0.1 m at the center of its surface.
The comb-shaped electrode 174 having a length of m and a length of 1.1 mm and the lead-out electrode 172 for grounding and inputting / outputting were formed on the periphery thereof by a vapor deposition film of chromium and gold. Further, a silicon oxide film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 174 that is directly joined to the lid portion 173 (hatched portion in FIG. 17B), and the surface thereof is slightly polished. To a thickness of about 1 μm for planarization, and the silicon compound film 175
Was formed. As a result, even when the substrate 171 is directly bonded, the lid 173 does not touch the comb-shaped electrode 174 formed on the substrate 171.
The lid portion 173 is a glass plate having a thickness of 2.8 mm × 1.4 mm × a thickness of 500 μm. In the case of the present embodiment, the glass plate of the lid portion 173 is the Y of the substrate 171.
The coefficient of thermal expansion of the cut lithium tantalate substrate is substantially the same as that of the cut lithium tantalate substrate so that thermal stress is not applied to the substrate 171 after the direct bonding and the resonance characteristics of the surface acoustic wave element are not deteriorated. Since the substrate 171 and the lid portion 173 are directly bonded to each other via the silicon compound film 175, the comb-shaped electrode 174 on the substrate 171 is connected to the lid portion 173.
Is substantially hermetically sealed by.

Example 18 (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 181 is a substrate, 182 is an extraction electrode, 183 is a lid, 184 is a comb electrode, and 185 is a silicon compound. In this embodiment, the substrate 181 has a length of 2.4 m.
It is a Y-cut lithium tantalate substrate of m × 2.8 mm × thickness 500 μm, and a width of 0.1 m at the center of its surface.
The comb-shaped electrode 184 having a length of m and a length of 1.1 mm and the lead-out electrode 182 for grounding and inputting / outputting were formed on the periphery thereof by a vapor deposition film of chromium and gold. Further, a silicon nitride film having a thickness of 2 μm is formed on a portion of the peripheral portion of the comb-shaped electrode 184 that is directly bonded to the lid portion 183 (hatched portion in FIG. 18B), and the surface thereof is slightly polished. To a thickness of about 1 μm for planarization.
Was formed. Accordingly, even when the substrate 181 is directly bonded, the lid 183 does not touch the comb-shaped electrode 184 formed on the substrate 181.
Further, the lid 183 is a glass plate of 2.8 mm × 1.4 mm × thickness of 500 μm. In the case of the present embodiment, the glass plate of the lid 183 is the Y of the substrate 181.
The coefficient of thermal expansion is substantially the same as that of the cut lithium tantalate substrate so that thermal stress is not applied to the substrate 181 after the direct bonding and the resonance characteristics of the surface acoustic wave element are not deteriorated. Since the substrate 181 and the lid portion 183 are directly bonded to each other via the silicon compound film 185, the comb-shaped electrode 184 on the substrate 181 is connected to the lid portion 183.
Is substantially hermetically sealed by.

Example 19 (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 191 is a substrate, 192 is an extraction electrode, 193 is a lid, 194 is a comb-shaped electrode, 195 is low-melting glass, and 1 is
96 is a metal film. In this embodiment, the substrate 1
91 is S of 2.4 mm × 2.8 mm × thickness 500 μm
A T-cut crystal plate with a width of 0.1 at the center of its surface.
mm, and the length of 1.1 mm, the comb-shaped electrode 194, and the ground and the extraction electrode 192 for input and output were formed on the periphery thereof by a vapor deposition film of chromium and gold. The lid 193 is an ST-cut quartz plate having a size of 1.4 mm × 2.8 mm × thickness of 500 μm. In the case of the present embodiment, the ST cut quartz plate of the lid 193 is the S of the substrate 191.
The T-cut quartz plate is used in such a direction that its coefficient of thermal expansion is substantially the same, and thermal stress is applied to the substrate 191 after direct bonding so that the resonance characteristics of the surface acoustic wave element are not deteriorated. Further, the central portion of the lid portion 193 was hollowed into a shape of 0.4 mm × 1.8 mm × depth of 1 μm by etching, and the portion corresponding to the extraction electrode 192 was hollowed into a shape of 1 μm in depth. Accordingly, even when the substrate 191 is directly bonded, the comb-shaped electrode 194 and the extraction electrode 1 formed on the substrate 191 are formed.
The lid portion 193 does not touch 92. Further, a metal film shield 196 for noise reduction is formed on the entire surface of the lid 193 by a vapor deposition film of chromium and gold. The substrate 191 and the lid 193 are directly joined after cleaning their surfaces, and the extraction electrode 1
Since the portion 92 is finally sealed by the low melting point glass 195, the comb-shaped electrode 19 on the substrate 191 is formed.
4 is substantially airtightly sealed by the lid portion 193.

(Example 20) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 201 is a substrate, 202 is an extraction electrode, 203 is a lid, 204 is a comb-shaped electrode, 205 is low-melting glass, and 2
Reference numeral 06 is a metal film. In this embodiment, the substrate 2
01 is 2.4 mm × 2.8 mm × 500 μm thick S
A T-cut crystal plate with a width of 0.1 at the center of its surface.
The comb-shaped electrode 204 having a length of 1.1 mm and a length of 1.1 mm and the lead-out electrode 202 for grounding and inputting / outputting were formed on the periphery thereof by a vapor deposition film of chromium and gold. The lid 203 is an ST-cut crystal plate having a size of 1.4 mm × 2.8 mm × a thickness of 500 μm. In the case of the present embodiment, the ST cut quartz plate of the lid 203 is the S of the substrate 201.
The T-cut quartz plate is used in such a direction that its coefficient of thermal expansion is substantially the same, so that thermal stress is not applied to the substrate 201 after direct bonding and the resonance characteristics of the surface acoustic wave element are not deteriorated. Further, the central portion of the lid portion 203 was etched into a shape of 0.4 mm × 1.8 mm × depth of 1 μm, and the portion corresponding to the extraction electrode 202 was hollowed into a shape of depth of 1 μm. This allows the comb-shaped electrode 204 and the extraction electrode 2 formed on the substrate 201 even when directly bonded to the substrate 201.
The lid portion 203 does not touch 02. Further, a metal film shield 206 for noise reduction is formed on the entire back surface of the substrate 201 by a vapor deposition film of chromium and gold. The substrate 201 and the lid 203 are directly joined after cleaning their surfaces, and the portion of the extraction electrode 202 is finally sealed by the low melting glass 205, so that the substrate 201 The comb electrode 204 is
The lid portion 203 is substantially hermetically sealed.
Needless to say, the metal film shield may be formed on both sides of the substrate surface and the lid surface. Further, it is needless to say that the metal film is not required to have the entire surface, but an area having a shielding effect is sufficient.

(Example 21) (a), (b) of FIG.
And (c) are an internal structure, a cross-sectional view, and an external view of the surface acoustic wave device according to the present embodiment. In these figures, 211 is a substrate, 212 is an extraction electrode, 213 is a lid, 214 is a comb-shaped electrode, 215 is low-melting glass, and 2 is
Reference numeral 16 denotes a roughened substrate back surface. In this embodiment, the substrate 211 is an ST-cut quartz plate having a size of 2.4 mm × 2.8 mm × a thickness of 500 μm, and a comb having a width of 0.1 mm and a length of 1.1 mm is formed at the center of the surface thereof. The mold electrode 214 and the lead-out electrode 212 for earth and input / output are formed on the periphery of the mold electrode 214 by a vapor deposition film of chromium and gold, and the back surface deteriorates in characteristics when surface acoustic waves excited on the front surface are reflected. On the back surface, the roughness was intentionally roughened so that waves were diffusely reflected, and the roughened substrate back surface 216 was obtained. The lid portion 213 has a size of 1.4 mm × 2.8 mm
A ST-cut quartz plate having a thickness of 500 μm. In the case of this embodiment, the ST-cut crystal plate of the lid 213 is
The substrate 2 is used in a direction in which the coefficient of thermal expansion is substantially the same as that of the ST-cut quartz plate of the substrate 211, and the substrate 2 is directly bonded.
The thermal stress is applied to 11 to prevent the resonance characteristics of the surface acoustic wave element from deteriorating. Further, the central portion of the lid portion 213 is hollowed out by etching into a shape of 0.4 mm × 1.8 mm × depth of 1 μm, and the extraction electrode 212 is also used.
The portion corresponding to was cut into a shape having a depth of 1 μm. Thus, even when the substrate 211 is directly bonded, the lid 213 does not touch the comb-shaped electrode 214 and the extraction electrode 212 formed on the substrate 211. The substrate 211 and the lid portion 213 are directly joined after cleaning their surfaces, and the portion of the extraction electrode 212 is finally sealed by the low melting point glass 215. The comb electrode 214 is substantially hermetically sealed by the lid 213.

Since the main point of the present invention described above is that the substrate and the lid are self-adhered by an inorganic covalent bond, the combination of the two is not limited to the above embodiment. Further, for the same reason, the film formed between the substrate and the lid may be a silicon film. Further, the type of substrate and the cut angle are not so important, and after selecting the substrate and its cut angle that can obtain the desired characteristics, the lid portion having substantially the same coefficient of thermal expansion can be appropriately selected accordingly. it can. Further, it goes without saying that lithium borate can be used as the substrate or the lid.

[0056]

As described above, according to the present invention, there is provided a surface acoustic wave device including at least a substrate having a surface acoustic wave element and a lid portion made of substantially the same material as the substrate, The substrate and the lid portion are self-bonded to each other by an inorganic covalent bond formed by the material itself, and the surface acoustic wave element portion is substantially hermetically sealed, so that the area required for hermetic sealing is reduced. Since it is small, the surface acoustic wave device can be downsized. In addition, since no adhesive is used, it does not change over time and has excellent durability.

According to the manufacturing method of the present invention, the surface acoustic wave device can be manufactured efficiently and rationally.

[Brief description of drawings]

FIG. 1A is an internal structural view of a surface acoustic wave device according to Example 1 of the present invention, FIG. 1B is a sectional view of the same, and FIG.

2A is an internal structural view of a surface acoustic wave device according to Embodiment 2 of the present invention, FIG. 2B is a sectional view of the same, and FIG.

3A is an internal structural view of a surface acoustic wave device according to Example 3 of the present invention, FIG. 3B is the same sectional view, and FIG. 3C is the same external view.

4A is an internal structural view of a surface acoustic wave device of Example 4 of the present invention, FIG. 4B is a sectional view of the same, and FIG. 4C is an external view thereof.

5A is an internal structural view of a surface acoustic wave device of Example 5 of the present invention, FIG. 5B is a sectional view of the same, and FIG. 5C is an external view thereof.

6A is an internal structural view of a surface acoustic wave device according to Example 6 of the present invention, FIG. 6B is the same sectional view, and FIG. 6C is the same external view.

7 (a) is a structural view of the inside of a surface acoustic wave device of Example 7 of the present invention, FIG. 7 (b) is the same sectional view, and FIG. 7 (c) is the same external view.

8A is an internal structural view of an 8th surface acoustic wave device according to an embodiment of the present invention, FIG. 8B is the same sectional view, and FIG. 8C is the same external view.

9A is an internal structural view of a surface acoustic wave device according to Example 9 of the present invention, FIG. 9B is a sectional view of the same, and FIG. 9C is an external view thereof.

FIG. 10A is an internal structural view of a surface acoustic wave device of Example 10 of the present invention, FIG. 10B is a sectional view of the same, and FIG.

11A is an internal structural view of an 11th surface acoustic wave device according to an embodiment of the present invention, FIG. 11B is a sectional view thereof, and FIG. 11C is an external view thereof.

12A is a structural view of the inside of a surface acoustic wave device of Example 12 of the present invention, FIG. 12B is a sectional view of the same, and FIG.

13A is a structural view of the inside of a surface acoustic wave element of Example 13 of the present invention, FIG. 13B is the same sectional view, and FIG. 13C is the same external view.

14A is an internal structural view of a surface acoustic wave element according to Example 14 of the present invention, FIG. 14B is a sectional view of the same, and FIG. 14C is an external view thereof.

15A is an internal structural view of a surface acoustic wave device according to Example 15 of the present invention, FIG. 15B is a sectional view of the same, and FIG. 15C is an external view thereof.

16A is an internal structural view of a surface acoustic wave element according to Example 16 of the present invention, FIG. 16B is a sectional view of the same, and FIG. 16C is an external view thereof.

17A is a structural diagram of the inside of a surface acoustic wave element of Example 17 of the present invention, FIG. 17B is the same sectional view, and FIG.

FIG. 18 (a) is an internal structural view of an eighteen surface acoustic wave device according to an embodiment of the present invention, FIG. 18 (b) is the same sectional view, and FIG. 18 (c) is the same external view.

19 (a) is a structural view of the inside of a surface acoustic wave element according to Example 19 of the present invention, FIG. 19 (b) is the same sectional view, and FIG. 19 (c) is the same external view.

20 (a) is a structural view of the inside of a surface acoustic wave element of Example 20 of the present invention, FIG. 20 (b) is the same sectional view, and FIG. 20 (c) is the same external view.

21A is a structural view of the inside of a surface acoustic wave element of Example 21 of the present invention, FIG. 21B is a sectional view of the same, and FIG.

22A is a structural view of the inside of a conventional surface acoustic wave device, FIG. 22B is a sectional view of the same, and FIG.

23 (a) is a cross-sectional view of the bonded plate before heat treatment expanded to the molecular level in Example 1 of the present invention, and FIG. 23 (b) is a combined view during heat treatment expanded to the same molecular level. (C) is a cross-sectional view of the bonded plates after the heat treatment, which is enlarged to the same molecular level.

[Explanation of symbols]

11, 21, 31, 41, 51, 61, 71, 81, 9
1, 101, 111, 121, 131, 141, 15
1,161,171,181,191,201,21
1,221 Substrate 12, 22, 32, 42, 52, 62, 72, 82, 9
2, 102, 112, 122, 132, 142, 15
2,162,172,182,192,202,212
Extraction electrodes 13, 23, 33, 43, 53, 63, 73, 83, 9
3,103,113,123,133,143,15
3,163,173,183,193,203,21
3,229 lid part 14,24,34,44,54,64,74,84,9
4,104,114,124,134,144,15
4,164,174,184,194,204,21
4,222 Comb type electrodes 15,25,35,45,55,65,75,85,1
95,205,215 Low melting point glass 95,105,115,125,135,145,15
5,165,175,185,195 Silicon compound film 196,206 Metal film 216 Roughened substrate back surface 223 Pad part 224 Ceramic case 225 Input / output terminal 226 Ground terminal 227 Bonding wire 228 Adhesive

 ─────────────────────────────────────────────────── ─── Continuation of the front page (31) Priority claim number Japanese Patent Application No. 5-211235 (32) Priority date Hei 5 (1993) August 26 (33) Priority claim country Japan (JP) (72) Inventor Kazuo Eda 1006 Kadoma, Kadoma-shi, Osaka Prefecture Matsushita Electric Industrial Co., Ltd.

Claims (16)

[Claims] 1. A surface acoustic wave device comprising at least a substrate having a surface acoustic wave element and a lid portion made of substantially the same material as that of the substrate, wherein the substrate and the lid portion are mutually adjacent to each other. A surface acoustic wave device characterized in that it is self-adhered by an inorganic covalent bond formed by the material itself, and the surface acoustic wave element portion is substantially hermetically sealed. 2. The surface acoustic wave device according to claim 1, wherein a space between the substrate and the lid is substantially airtightly filled with silicon or a silicon compound. 3. The surface acoustic wave device according to claim 1, wherein the substrate is at least one substance selected from quartz, lithium niobate, lithium tantalate and lithium borate. 4. The surface acoustic wave device according to claim 2, wherein the silicon compound is silicon oxide or silicon nitride. 5. The surface acoustic wave device according to claim 1, wherein the thermal expansion coefficient of the lid portion is substantially equal to the thermal expansion coefficient of the substrate. 6. The surface acoustic wave device according to claim 1, wherein a metal film is provided on at least one of the front surface of the lid portion and the back surface of the substrate. 7. The surface acoustic wave device according to claim 1, wherein the lid is made of at least one substance selected from quartz, glass, lithium niobate, lithium tantalate and lithium borate. 8. The surface acoustic wave device according to claim 1, wherein the portion of the extraction electrode between the substrate and the lid is filled with low melting point glass. 9. A substrate having a surface acoustic wave element and a surface of a lid portion made of the same material as the substrate, at least one substance selected from glass and quartz, are formed by the following methods (A) and (B). A method of manufacturing a surface acoustic wave device, characterized in that the surface acoustic wave element portion is substantially hermetically sealed by fixing the surface acoustic wave element portion by at least one selected method. (A) A method in which the surface of the substrate and the surface of the lid are cleaned, and then a voltage is applied to the interface to fix them by anodic bonding. (B) The surface of the substrate and the surface of the lid are cleaned and then subjected to hydrophilic treatment. Method of contacting, heat-treating, and fixing the substrate and the lid by direct bonding 10. The method of manufacturing a surface acoustic wave device according to claim 9, wherein the surface of the lid is made of silicon or a silicon compound. 11. The method of manufacturing a surface acoustic wave device according to claim 9, wherein the substrate surface is formed of silicon or a silicon compound. 12. The method of manufacturing a surface acoustic wave device according to claim 9, wherein the back surface of the substrate is roughened. 13. The method of manufacturing a surface acoustic wave device according to claim 9, wherein a portion of the extraction electrode between the substrate and the lid is filled with low melting point glass. 14. The method of manufacturing a surface acoustic wave device according to claim 9, wherein a voltage is applied to the interface while heating the substrate and the lid during anodic bonding. 15. The method of manufacturing a surface acoustic wave device according to claim 14, wherein the heating temperature is 100 ° C. or higher. 16. The method of manufacturing a surface acoustic wave device according to claim 14, wherein the heating temperature is 200 ° C. or higher.