JP3308749B2 - Method for manufacturing surface acoustic wave device, and surface acoustic wave device manufactured using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a surface acoustic wave device and a surface acoustic wave device manufactured using the same.

[0002]

2. Description of the Related Art Conventionally, a surface acoustic wave device (hereinafter referred to as a SAW filter), which has been frequently used as a filter for mobile communication, generally has a Y-cut or three-degree rotation.
6 degree rotation X cut lithium tantalate (LiTaO)
₃ ) Alternatively, a comb-shaped electrode or the like is arranged and formed on a lithium niobate (LiNbO ₃ ) single crystal substrate having a Y cut of 64 degrees or a Y cut of 128 degrees.

[0003] The electrode metal in the SAW filter is required to be excellent in fine workability, to have a small specific gravity in order to reduce the electrode load mass effect, and to have a small electric resistance in order to reduce insertion loss. For this purpose, aluminum or an aluminum-based alloy is generally used. However, in order to improve the resistance to stress migration generated by the vibration of the piezoelectric substrate due to the surface acoustic wave, that is, to improve the power resistance, aluminum as an electrode material of the SAW filter is used. An aluminum alloy obtained by adding a trace amount of copper (Cu), silicon (Si), titanium (Ti), palladium (Pd), or the like to (Al) is used.

[0004] However, although the power durability of the electrode is improved as the concentration of the added element is increased, problems such as an increase in insertion loss and an etching residue during electrode processing occur.
High concentrations are undesirable.

Therefore, as a countermeasure against the above-mentioned electrode stress migration of the SAW filter, Japanese Journal Applied Physics (Jpn. J. Ap.
pl. Phys. 33) 3015 (1994)
Next, when a 36-degree rotated Y-cut lithium tantalate substrate is etched with hydrofluoric acid to form an aluminum film by an ion beam sputtering method, a (111) oriented single crystal aluminum film is obtained, and this film is used as an electrode. It has been reported that a SAW filter has extremely excellent power durability as compared with a conventional polycrystalline aluminum electrode.

[0006]

However, in the above-described method for manufacturing a SAW filter, although it has extremely excellent power durability as compared with a conventional polycrystalline aluminum electrode, a single crystal on a lithium tantalate single crystal substrate is provided. It has been found that it is difficult to form a crystalline aluminum film, and there is a problem that the production yield is extremely low.

This problem will be described with reference to FIG.

FIGS. 2A and 2B are schematic diagrams showing the state of the substrate surface. FIG. 2A shows a state in which a surface altered layer is present, and FIG. 2B shows a state in which a low-index crystal plane is formed. FIG. 3C is a diagram showing a state in which a low-index crystal plane does not appear.

Generally, in order to form a single crystal metal film, a single crystal substrate suitable for the growth direction of the metal film or a buffer layer epitaxially grown on the single crystal substrate is required.

On the surface of a single crystal piezoelectric substrate such as LiTaO ₃ or LiNbO ₃ , a polishing process or the like causes
As shown in (a), there is a surface layer having a disordered crystal structure. Therefore, the raw lattice plane having the original crystal structure of the single crystal is covered with such a surface-altered layer, and unless some pretreatment is performed to remove the surface-altered layer, a single-crystal aluminum film cannot be formed. It becomes difficult.

By the way, the single crystal LiTaO ₃ and LiNbO ₃ substrates used for the SAW filter, except for a part,
Since the specific crystal plane is not parallel to the substrate surface, the substrate surface usually does not match the crystallographic lattice plane in such a substrate.

Since a single-crystal metal film generally grows on a substrate lattice plane having a low index, it is difficult to form a single-crystal aluminum film on a substrate where the crystallographic lattice plane does not coincide with the substrate surface. It is necessary to create a low-index crystal plane on the substrate as shown in FIG.

However, in the above-described conventional method of manufacturing a SAW filter in which the substrate is pretreated with hydrofluoric acid, even if a surface layer having a disordered crystal structure on the substrate surface can be removed, the etching process is performed uniformly. First, as shown in FIG. 2C, it is considered that a single crystal aluminum film cannot be formed with a high yield because a low-index crystal plane suitable for growing the single crystal aluminum film does not appear.

The present invention has been made in view of the above-mentioned problems of the prior art, and can be manufactured with a high yield on a single crystal substrate of lithium tantalate or lithium niobate, and has a high durability. An object of the present invention is to provide a method of manufacturing a surface acoustic wave device having excellent power properties and a surface acoustic wave device manufactured using the same.

[0015]

In order to achieve the above object, the present invention provides a surface acoustic wave having a single crystal aluminum or aluminum alloy film electrode on a lithium tantalate or lithium niobate single crystal piezoelectric substrate. In the method of manufacturing a device, the deteriorated substrate surface layer on the single crystal piezoelectric substrate may be formed by bonding the lithium tantalate and the lithium niobate together.
The ion source is arranged such that the irradiation direction of the ion beam is within ± 20 ° from the position where the irradiation direction of the ion beam is parallel or perpendicular to the axis direction perpendicular to the crystal plane having the low index closest to the surface of the piezoelectric substrate. After removing by ion beam etching, a single crystal aluminum or aluminum alloy film is formed on the single crystal piezoelectric substrate.

Further, a comb-shaped electrode made of a (100) oriented single crystal aluminum or aluminum alloy film is provided on a lithium tantalate or lithium niobate single crystal piezoelectric substrate.

Further, a comb-shaped electrode made of a (110) oriented single crystal aluminum or aluminum alloy film is provided on a lithium tantalate or lithium niobate single crystal piezoelectric substrate.

Further, a comb-shaped electrode made of a (111) oriented single crystal aluminum or aluminum alloy film is provided on a lithium tantalate or lithium niobate single crystal piezoelectric substrate.

[0019]

Next, the operation of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram for explaining ion beam etching in the method for manufacturing a surface acoustic wave device according to the present invention. FIG. 3 is a schematic cross-sectional view showing a growth state of a single crystal aluminum film on a substrate when ion beam etching, which is a feature of the present invention, is performed.

In the present invention, as shown in FIG. 1, the arrangement is such that the principal axis direction of the substrate and the irradiation direction of the ion beam are within ± 20 ° from the parallel or right angle depending on the cut angle of the substrate to be used. The substrate is subjected to ion beam etching, so that a low-index crystal surface having steps according to the substrate used appears.

In the arrangement shown in FIG. 1A, the axis 40 perpendicular to the low index plane 30 closest to the surface of the substrate 20 is parallel to the irradiation direction of the ion source 10, and in the arrangement B, the low index plane 30
The axis 40 perpendicular to the axis and the irradiation direction of the ion source 10 are perpendicular. In any arrangement, the irradiation direction of the ion source 10 is ± 20 ° with respect to the axis 40 perpendicular to the low index plane of the substrate.
In this case, a low-index crystal surface having steps as shown in FIG. 2B appears, so that single-crystal aluminum can be easily grown as shown in FIG.

[0023]

Embodiments of the present invention will be described below.

FIG. 4 is a schematic structural view of an ion beam etching apparatus used in the pretreatment of a substrate in the method of manufacturing a surface acoustic wave device according to the present invention.

The ion beam etching apparatus shown in FIG. 4 comprises a Kauffman-type ion source 10 for irradiating an ion beam to a substrate, and a goniometer 70 capable of arbitrarily changing the direction of the substrate with respect to the ion beam irradiation direction of the ion source 10. , A substrate holder 60 provided on the goniometer 70 for mounting the substrate, and a cryopump 80 which is a built-in pump. The substrate holder 60 has the substrate 20 mounted thereon. Further, an argon gas is supplied to the ion source 10 from a gas cylinder (not shown) via a mass flow meter 90. Here, the gas supplied to the ion source 10 is not limited to the argon gas, but may be a rare gas such as xenon or krypton.

After performing a pretreatment, that is, a removal process of a surface altered layer generated on the substrate surface by a polishing process or the like by an ion beam etching apparatus shown in FIG. 4, the substrate is transferred to an aluminum electrode film forming apparatus, 100 nm Al by vapor deposition or ion beam sputtering.
-2 wt% Cu alloy film or Al-1 wt% Si-0.
A 5% Cu alloy film was produced.

The manufacturing conditions by the electron beam evaporation method were as follows: background vacuum degree 3 × 10 ⁻¹⁰ Torr or less Vacuum degree during evaporation 5 × 10 ⁻⁸ Torr or less Substrate temperature 100 ° C. Film formation rate 0.05 nm / s.

On the other hand, the manufacturing conditions by the ion beam sputtering method are as follows: background vacuum degree 1 × 10 ⁻⁷ Torr or less Argon pressure during sputtering 2 × 10 ⁻⁴ Torr Substrate temperature 25 ° C. (room temperature) Film formation rate 0.1 nm / s The ion source acceleration voltage was 1200 V.

The evaluation of the crystallinity of the manufactured aluminum-based alloy film was performed by high-speed reflection electron beam diffraction (RHEED) (provided in an aluminum electrode film forming apparatus) and X-ray diffraction (XRD).

Thereafter, a SAW having a center frequency of 670 MHz
A filter was made.

For comparison, an aluminum alloy film was formed on a substrate pretreated with hydrofluoric acid, and the same SAW filter was manufactured. The pretreatment with hydrofluoric acid was performed by immersing each substrate in a 45% hydrofluoric acid aqueous solution at 40 ° C. for 1 minute.

The power durability of the manufactured SAW filter was evaluated by the system and method described in JP-A-3-48511.

FIG. 5 is a diagram showing a system for evaluating the power durability of a SAW filter described in Japanese Patent Application Laid-Open No. 3-48511.

As shown in FIG. 5, the evaluation system used in this embodiment has a SAW in which the output of the signal generator 100 is connected to the power amplifier 110 and the output of the power amplifier 110 is provided inside the thermostat 120. Filter 13
0, the output of the SAW filter 130 is connected to the power meter 140, and the output of the power meter 140 is fed back to the signal generator 100 via the computer 150.

With the above configuration, the output signal from the signal generator 100 is power-amplified by the power amplifier 110, and the output is applied to the SAW filter 130 installed in the thermostat 120. . Also, SAW
The output of the filter 130 is input to the power meter 140 to measure the level.
Output from the signal generator 100 via the computer 150
The frequency of the applied signal is always the peak frequency of the transmission characteristics by controlling the frequency of the signal generator 100.

In the following embodiment, +30 dBm (1 W)
And the temperature of the thermostat 120 was set to 85 ° C. to accelerate the deterioration.

Further, regarding the life of the SAW filter,
Output of SAW filter before test and time t after start of test
Output respectively, when the P _0, P (t) at time point was lowered 1.0dB from the initial value, i.e., the life of the SAW filter when it becomes _{P (t) ≦ P 0 -1.0} (dB) Defined.

As a piezoelectric substrate, X-cut LiTaO ₃
(Hereinafter referred to as LT) substrate, Z-cut LT substrate, 36 °
Rotated Y-cut LT substrate, 128 ° rotated Y-cut LiNb
O ₃ (hereinafter referred to as LN) substrate, 41 ° rotation Y cut L
The N substrate, the 64 ° rotated Y cut LN substrate, and the Z cut LN substrate were examined.

(First Embodiment) As a first embodiment, a case will be described in which an X-cut LT substrate whose substrate surface coincides with the low index plane of the crystal is used.

In the case of the piezoelectric substrate according to the present embodiment, the crystal plane having the lowest index relative to the substrate surface is the (100) plane (the index used to represent hexagonal crystal is (2, -1, -1, -1).
0) plane). X axis <100> perpendicular to this plane to Y
The substrate was pretreated by irradiating the substrate with an ion beam at an angle θ toward the axis (<010> direction).

The pretreatment conditions for the substrate were as follows: argon gas pressure 1 ×
10 ^-4 Torr, an acceleration voltage of 1000 V, an ion current density of 0.5 A / cm ² , and an irradiation time of 1 to 5 minutes. Al-
The 2 wt% Cu film was formed by an electron beam evaporation method.

Table 1 shows the irradiation angle, irradiation time, crystallinity of the aluminum film by RHEED and XRD, and the life of the SAW filter in this embodiment.

As is clear from Table 1, if the irradiation direction of the ion beam is parallel to the X axis or within a range of ± 20 ° from the vertical direction, a (110) oriented single crystal aluminum film is formed on the substrate. This single-crystal aluminum electrode film is about 10 times smaller than a polycrystalline aluminum electrode film.
It can be seen that it has 0 times the power durability life.

In this embodiment, the irradiation direction of the ion beam is changed from the X axis to the Y axis. However, the angle from the X axis is important. Did not depend. In addition, almost the same results were obtained for the Al-2 wt% Cu film produced by the ion beam sputtering method.

[0045]

[Table 1] (Second Embodiment) As a second embodiment, a case where a Z-cut LT substrate and a Z-cut LN substrate are used will be described.

In the case of the piezoelectric substrate according to the present embodiment, the crystal plane having the low index closest to the substrate surface is the (001) plane (the index used for displaying hexagonal crystal is (0001) plane).
Plane). Z-axis <001> perpendicular to this (001) plane
The substrate was pre-treated by irradiating the substrate with an ion beam at an angle θ toward the Y-axis (<010> direction).

The pretreatment conditions for the substrate are the same as in the first embodiment. The Al-2 wt% Cu film was produced by an electron beam evaporation method.

Table 2 shows the irradiation angles of the substrate etching ion beam, RHEED and XR in this embodiment.
4 is a table showing the crystallinity of the aluminum film and the life of the SAW filter according to D.

In Table 2, almost the same results were obtained for both the LT substrate and the LN substrate, so only the results for the Z-cut LT substrate are shown.

As is clear from Table 2, if the irradiation direction of the ion beam is parallel to the X axis or within a range of ± 20 ° from the vertical direction, a (111) single crystal aluminum film is formed on the substrate. This single-crystal aluminum electrode film is about 10 times smaller than a polycrystalline aluminum electrode film.
It can be seen that it has 0 times the power durability life.

In the present embodiment, the irradiation direction of the ion beam is changed from the Z axis to the Y axis. However, the angle from the Z axis is important. Did not depend. In addition, almost the same results were obtained for the Al-2 wt% Cu film produced by the ion beam sputtering method.

[0052]

[Table 2] Third Embodiment As a third embodiment, a case where a 36 ° Y-cut LT substrate is used will be described.

In the case of the piezoelectric substrate according to the present embodiment, the crystal plane having the lowest index closest to the substrate surface is the (012) plane (the index used for displaying hexagonal crystal is (0, 1,-).
1, 2) plane). An axis perpendicular to the (012) plane (an axis inclined by 3.1 ° from the axis perpendicular to the substrate surface toward the Y axis)
The substrate was pre-treated by irradiating the substrate with an ion beam at an angle θ from − to the −Y axis (<0, −1, 0> direction).

The pretreatment conditions for the substrate are the same as in the first embodiment. Al-1wt% by ion beam sputtering
A Si-0.5 wt% Cu alloy film was produced.

Table 3 shows the irradiation angle, RHEED and XR of the ion beam for etching the substrate in this embodiment.
4 is a table showing the crystallinity of the aluminum film and the life of the SAW filter according to D.

As is clear from Table 3, if the irradiation direction of the ion beam is parallel to the axis perpendicular to the (012) plane or within a range of ± 20 ° from the perpendicular direction, the (111) A single-crystal aluminum film of the orientation is formed,
It can be seen that this single-crystal aluminum electrode film has a power durability that is about 100 times that of a polycrystalline Al electrode film.

In this embodiment, the irradiation direction of the ion beam is changed from the axis perpendicular to the (012) plane to the -Y axis, but the irradiation direction of the ion beam is changed to the (012) plane. The angle from the vertical axis was important and independent of the azimuth.

[0058]

[Table 3] (Fourth Embodiment) In the above third embodiment, Al-1w
Although a t% Si-0.5wt% Cu alloy film was produced by the ion beam sputtering method, in the fourth embodiment, the ion beam etching conditions for the substrate were made exactly the same as in the third embodiment, and the Al- The case where a 1 wt% Si-0.5 wt% Cu alloy film is produced by electron beam evaporation will be described.

Table 4 shows the irradiation angles, RHEED and XR of the ion beam for etching the substrate in this embodiment.
4 is a table showing the crystallinity of the aluminum film and the life of the SAW filter according to D.

When the above-mentioned aluminum alloy film was produced by electron beam evaporation, a (100) oriented single crystal aluminum film was obtained. A SAW filter using this single crystal aluminum film as an electrode, as shown in Table 4, was prepared as follows. It can be seen that it has about 100 times the power durability life as compared with the crystalline aluminum electrode film.

In the present embodiment, as in the third embodiment, the irradiation direction of the ion beam was changed from the axis perpendicular to the (012) plane toward the -Y axis.
12) The angle from the axis perpendicular to the plane was important and independent of the azimuth.

[0062]

[Table 4] (Fifth Embodiment) As a fifth embodiment, a case where a 128 ° Y-cut LN substrate is used will be described.

In the case of the piezoelectric substrate according to the present embodiment, the crystal plane of the low index closest to the substrate surface is (0, −1,
2) Plane (index used to represent hexagonal system is (0,-
1, 1, 2) plane). An axis perpendicular to the (0, -1, 2) plane (5.3 from the axis perpendicular to the substrate surface to the -Y axis).
° axis) to the Y axis (<010> direction)
The substrate was pretreated by irradiating an ion beam at an angle θ.

The pretreatment condition of the substrate is the same as that of the first embodiment, and the Al-2w
A t% Cu film was formed.

Table 5 is a table showing the irradiation angle of the ion beam for ion beam etching, the crystallinity of the Al film by RHEED and XRD, and the life of the SAW filter in this embodiment.

As is clear from Table 5, if the direction of irradiation of the ion beam is parallel to the axis perpendicular to the (0, -1, 2) plane or within a range of ± 20 ° from the perpendicular direction, this substrate A single crystal aluminum film having a (111) orientation is formed thereon, and it can be seen that the single crystal aluminum electrode film has a power durability about 100 times that of a polycrystalline aluminum electrode film.

In the present embodiment, the irradiation direction of the ion beam is changed from the axis perpendicular to the (0, -1, 2) plane toward the Y axis.
The angle from the axis perpendicular to the (0, -1, 2) plane was important and did not depend on the azimuth.

[0068]

[Table 5] (Sixth Embodiment) In the above fifth embodiment, Al-2w
Although the t% Cu alloy film was produced by the ion beam sputtering method, in the present embodiment, the ion beam etching conditions for the substrate were made exactly the same as in the fifth embodiment, and Al-2w was used.
A case where a t% Cu alloy film is manufactured by electron beam evaporation will be described.

Table 6 shows the irradiation angle, RHEED and XR of the ion beam for etching the substrate in this embodiment.
4 is a table showing the crystallinity of the aluminum film and the life of the SAW filter according to D.

When the above-mentioned aluminum alloy film was produced by electron beam evaporation, a (100) oriented single-crystal aluminum film was obtained. It can be seen that the device has a power durability life approximately 100 times that of the crystalline Al electrode film.

In this embodiment, as in the fifth embodiment, the irradiation direction of the ion beam is (0, -1,
2) The angle was changed from the axis perpendicular to the surface to the Y axis,
The angle from the axis perpendicular to the (0, -1, 2) plane was important and did not depend on the azimuth.

[0072]

[Table 6] (Seventh Embodiment) As a seventh embodiment, a case where a 41 ° Y-cut LN substrate is used will be described.

In the case of the piezoelectric substrate in this embodiment, the crystal plane having the lowest index closest to the substrate surface is the (012) plane (the index used for displaying hexagonal crystal is (0, 1,-).
1, 2) plane). An axis perpendicular to the (012) plane (an axis inclined by 8.3 ° from the axis perpendicular to the substrate surface toward the Y axis)
The substrate was pre-treated by irradiating the substrate with an ion beam at an angle θ from − to the −Y axis (<0, −1, 0> direction).

The conditions for the pretreatment of the substrate were the same as those in the first embodiment, and the Al-1w
A t% Si-0.5 wt% Cu film was produced.

Table 7 is a table showing the irradiation angle of the ion beam for etching the substrate, the crystallinity of the aluminum film by RHEED and XRD, and the life of the SAW filter.

As is clear from Table 7, if the irradiation direction of the ion beam is parallel to the axis perpendicular to the (012) plane or within a range of ± 20 ° from the vertical direction, the (111) A single-crystal aluminum film of the orientation is formed,
It can be seen that this single-crystal aluminum electrode film has a power durability about 100 times that of a polycrystalline aluminum electrode film.

In this embodiment, the ion beam irradiation direction is changed from the axis perpendicular to the (012) plane toward the -Y axis.
12) The angle from the axis perpendicular to the plane was important and independent of the azimuth.

[0078]

[Table 7] (Eighth Embodiment) In the above seventh embodiment, Al-1w
Although the t% Si-0.5wt% Cu alloy film was formed by the ion beam sputtering method, in this embodiment, the ion beam etching conditions for the substrate were made exactly the same as in the seventh embodiment, and the Al-1wt% Si- The case where a 0.5 wt% Cu alloy film is produced by electron beam evaporation will be described.

Table 8 shows the irradiation angles of the substrate etching ion beam, RHEED and XR in this embodiment.
4 is a table showing the crystallinity of the aluminum film and the life of the SAW filter according to D.

When the above-mentioned aluminum-based alloy film was produced by electron beam evaporation, a (100) -oriented single-crystal aluminum film was obtained. It can be seen that it has about 100 times the power durability life as compared with the crystalline aluminum electrode film.

In this embodiment, as in the seventh embodiment, the direction of irradiation of the ion beam was changed from the axis perpendicular to the (012) plane toward the -Y axis.
12) The angle from the axis perpendicular to the plane was important and independent of the azimuth.

[0082]

[Table 8] (Ninth Embodiment) As a ninth embodiment, a case where a 64 ° Y-cut LN substrate is used will be described.

In the case of the piezoelectric substrate in this embodiment, the crystal plane having the lowest index closest to the substrate surface is the (001) plane (the index used for displaying hexagonal crystal is (0001) plane).
Plane). From the axis perpendicular to the (001) plane (the axis inclined 26 ° from the axis perpendicular to the substrate surface toward the Y axis) toward the −Y axis (<0, −1, 0> direction) at an angle θ Pretreatment of the substrate was performed by irradiation with an ion beam.

The conditions for the pretreatment of the substrate were the same as those in the first embodiment, and the Al-1w
A t% Si-0.5wt% Cu alloy film was produced.

Table 9 is a table showing the irradiation angle of the ion beam for etching the substrate, the crystallinity of the Al film by RHEED and XRD, and the lifetime of the SAW filter.

As is clear from Table 9, if the irradiation direction of the ion beam is parallel to the axis perpendicular to the (001) plane or within a range of ± 20 ° from the perpendicular direction, the (111) A single-crystal aluminum film of the orientation is formed,
It can be seen that this single-crystal aluminum electrode film has a power durability about 100 times that of a polycrystalline aluminum electrode film.

In this embodiment, the ion beam irradiation direction is changed from the axis perpendicular to the (001) plane to the -Y axis.
01) The angle from the axis perpendicular to the plane was important and did not depend on the azimuth. In addition, Al beam is deposited by electron beam evaporation.
Although a -1 wt% Si-0.5 wt% Cu alloy film was produced, almost the same results as in Table 9 were obtained.

[0088]

[Table 9]

[0089]

Since the present invention is constructed as described above, it has the following effects.

[0090] The substrate surface affected layer on a single crystal piezoelectric substrate, data
Lithium tantalate and lithium niobate single crystal piezoelectric substrate table
Ion beam etching by arranging the ion source so that the irradiation direction of the ion beam is within ± 20 ° from the position where the irradiation direction of the ion beam is parallel or perpendicular to the axis direction perpendicular to the crystal plane having the low index closest to the plane after removal by performing, for which so as to form a single crystal aluminum or an aluminum alloy film on a single crystal piezoelectric substrate, a single imaging
The low index plane of the substrate material required for forming a monocrystalline aluminum or aluminum-based alloy film can be exposed.
Therefore, unlike the substrate pretreatment using hydrofluoric acid, a single crystal aluminum film or an aluminum-based alloy film can be formed with high yield.

By providing such a comb-shaped electrode made of a single crystal aluminum or aluminum alloy film, the power durability of the electrode of the surface acoustic wave device can be remarkably improved, and a high-concentration additive element is not required. In addition, a SAW filter can be manufactured with a high yield without increasing insertion loss or generating etching residue during electrode processing.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining ion beam etching in a method for manufacturing a surface acoustic wave device according to the present invention.

FIG. 2 is a schematic diagram showing a state of a substrate surface;
(A) is a diagram showing a state where a surface altered layer is present,
(B) is a diagram showing a state where a low-index crystal plane is formed,
(C) is a diagram showing a state in which a low-index crystal plane does not appear.

FIG. 3 is a schematic cross-sectional view showing a growth state of a single crystal aluminum film on a substrate when ion beam etching, which is a feature of the present invention, is performed.

FIG. 4 is a schematic configuration diagram of an ion beam etching apparatus used in a substrate pretreatment in the method of manufacturing a surface acoustic wave device according to the present invention.

FIG. 5 is a diagram showing an S described in Japanese Patent Application Laid-Open No. 3-48511.
It is a figure showing the evaluation system of the power durability of an AW filter.

[Explanation of symbols]

 Reference Signs List 10 ion source 20 substrate 30 low-index crystal plane closest to substrate surface 40 axis perpendicular to low-index plane of substrate 50 ion beam 60 substrate holder 70 goniometer 80 cryopump 90 mass flow meter 100 signal generator 110 power amplifier 120 constant temperature bath 130 SAW filter 140 Power meter 150 Computer

Continuation of the front page (56) References JP-A-5-199062 (JP, A) JP-A-6-45288 (JP, A) JP-A-4-23471 (JP, A) JP-A-62-234319 (JP) JP-A-4-196610 (JP, A) JP-A-4-78209 (JP, A) JP-A-57-15514 (JP, A) JP-A-6-132777 (JP, A) 5-226337 (JP, A) JP-A-5-183373 (JP, A)

Claims (20)

(57) [Claims] 1. A method for manufacturing a surface acoustic wave device comprising an electrode made of a single-crystal aluminum or an aluminum-based alloy film on a lithium tantalate or lithium niobate single-crystal piezoelectric substrate, wherein the substrate on the single-crystal piezoelectric substrate is provided. the surface alteration layer, the tantalum
The irradiation direction of the ion beam is within ± 20 ° from the position where the irradiation direction of the ion beam is parallel or perpendicular to the axis direction perpendicular to the crystal plane having the low index closest to the surface of the lithium luate or lithium niobate single crystal piezoelectric substrate A method for manufacturing a surface acoustic wave device, comprising: forming a single-crystal aluminum or aluminum-based alloy film on the single-crystal piezoelectric substrate after removing by performing ion beam etching with an ion source arranged as described above. 2. Manufacturing of the surface acoustic wave device according to claim 1.
In the method, The single crystal piezoelectric substrate is made of X-cut lithium tantalate.
And The X-cut lithium tantalate is used as the substrate surface altered layer.
Has a low index closest to the surface of the single crystal piezoelectric substrate (100)
Of the ion beam in the <100> axis direction perpendicular to the crystal plane.
± 2 from the position where the irradiation direction is parallel or vertical
Arrange the ion source so that it is within the range of 0 °.
After the removal by performing
Single-crystal aluminum or aluminum
Surface acoustic wave device characterized by forming a film based alloy film
Manufacturing method. 3. Manufacturing of the surface acoustic wave device according to claim 1.
In the method, The single crystal piezoelectric substrate is a Z-cut lithium tantalate or
Is Z-cut lithium niobate; The substrate surface altered layer is formed by using the Z-cut lithium tantalate.
Or on Z-cut lithium niobate single crystal piezoelectric substrate surface
<00 perpendicular to the (001) crystal plane having the closest low index
1) The irradiation direction of the ion beam is parallel to the axial direction or
It will be within ± 20 ° from each vertical position
Ion beam etching with an ion source
After removing by single crystal on the single crystal piezoelectric substrate
Forming aluminum or aluminum alloy film
A method for manufacturing a surface acoustic wave device. 4. Production of the surface acoustic wave device according to claim 1.
In the method, The single crystal piezoelectric substrate is rotated by 36 ° Y-cut tantalum liquor.
It is titanium, The substrate surface deteriorated layer is subjected to the 36 ° rotation Y-cut tantalum.
Has a low index closest to the surface of lithium oxide single crystal piezoelectric substrate
(012) The direction of the ion beam in the axial direction perpendicular to the crystal plane
± 2 from the position where the irradiation direction is parallel or vertical
Arrange the ion source so that it is within the range of 0 °.
After the removal by performing
Single-crystal aluminum or aluminum
Surface acoustic wave device characterized by forming a film based alloy film
Manufacturing method. 5. Manufacturing of the surface acoustic wave device according to claim 1.
In the method, The single-crystal piezoelectric substrate is rotated by 128 ° Y-cut niobate
It is titanium, The substrate surface altered layer is formed by rotating the 128 ° rotated Y cut niobium.
Has a low index closest to the surface of lithium oxide single crystal piezoelectric substrate
Ion beam in the axial direction perpendicular to the (0, -1,2) crystal plane.
From the position where the irradiation direction of the
The ion source so that it is within ± 20 °.
After removal by performing on-beam etching,
Single crystal aluminum or aluminum on a single crystal piezoelectric substrate
Elastic surface characterized by forming a minium-based alloy film
Method of manufacturing wave device. 6. Manufacturing of the surface acoustic wave device according to claim 1.
In the method, The single crystal piezoelectric substrate is rotated by 41 ° Y-cut niobate
Um The substrate surface deteriorated layer is subjected to the 41 ° rotation Y-cut niobate.
Has a low index closest to the surface of the lithium single crystal piezoelectric substrate
(012) The direction of the ion beam in the axial direction perpendicular to the crystal plane
± 2 from the position where the irradiation direction is parallel or vertical
Arrange the ion source so that it is within the range of 0 °.
After the removal by performing
Single-crystal aluminum or aluminum
Surface acoustic wave device characterized by forming a film based alloy film
Manufacturing method. 7. Manufacturing of the surface acoustic wave device according to claim 1.
In the method, The single crystal piezoelectric substrate is rotated by 64 ° Y-cut niobate
Um The substrate surface altered layer is coated with the 64 ° -rotated Y-cut niobate.
Has a low index closest to the surface of the lithium single crystal piezoelectric substrate
Of the ion beam in the axial direction perpendicular to the (001) crystal plane.
± 2 from the position where the irradiation direction is parallel or vertical
Arrange the ion source so that it is within the range of 0 °.
Removed by performing Later, the simple connection
Single-crystal aluminum or aluminum
Surface acoustic wave device characterized by forming a film based alloy film
Manufacturing method. 8. A surface acoustic wave device manufactured using the method for manufacturing a surface acoustic wave device according to claim 1, wherein a (100) orientation is provided on the lithium tantalate or lithium niobate single crystal piezoelectric substrate. A surface acoustic wave device comprising a comb-shaped electrode made of a single-crystal aluminum or aluminum-based alloy film. 9. Manufacturing of the surface acoustic wave device according to claim 4.
A surface acoustic wave device manufactured using the method, 36 ° rotation Y-cut lithium tantalate single crystal piezoelectric
(100) single crystal aluminum or
Having a comb-shaped electrode made of an aluminum-based alloy film
Characteristic surface acoustic wave device. 10. Production of the surface acoustic wave device according to claim 5.
A surface acoustic wave device manufactured by using the manufacturing method, 128 ° rotation Y-cut lithium niobate single crystal piezoelectric
(100) single crystal aluminum or
Having a comb-shaped electrode made of an aluminum-based alloy film
Characteristic surface acoustic wave device. 11. A surface acoustic wave device according to claim 6.
A surface acoustic wave device manufactured by using the manufacturing method, 41 ° rotation Y-cut lithium niobate single crystal piezoelectric
(100) single crystal aluminum or
Having a comb-shaped electrode made of an aluminum-based alloy film
Characteristic surface acoustic wave device. 12. A surface acoustic wave device manufactured by using the method for manufacturing a surface acoustic wave device according to claim 1, wherein a (110) orientation is provided on the lithium tantalate or lithium niobate single crystal piezoelectric substrate. A surface acoustic wave device comprising a comb-shaped electrode made of a single-crystal aluminum or aluminum-based alloy film. 13. The surface acoustic wave device according to claim 2,
A surface acoustic wave device manufactured by using the manufacturing method, On the X-cut lithium tantalate single crystal piezoelectric substrate
(110) single crystal aluminum or aluminum
Characterized by having a comb-shaped electrode made of an aluminum-based alloy film
Surface acoustic wave device. 14. A surface acoustic wave device manufactured by using the method for manufacturing a surface acoustic wave device according to claim 1, wherein a (111) orientation is provided on the lithium tantalate or lithium niobate single crystal piezoelectric substrate. A surface acoustic wave device comprising a comb-shaped electrode made of a single-crystal aluminum or aluminum-based alloy film. 15. Manufacturing of the surface acoustic wave device according to claim 3.
A surface acoustic wave device manufactured by using the manufacturing method, On the Z-cut lithium tantalate single crystal piezoelectric substrate
(111) single crystal aluminum or aluminum
Characterized by having a comb-shaped electrode made of an aluminum-based alloy film
Surface acoustic wave device. 16. The surface acoustic wave device according to claim 3,
A surface acoustic wave device manufactured by using the manufacturing method, (1) On the Z-cut lithium niobate single crystal piezoelectric substrate,
11) Single-crystal aluminum or aluminum with orientation
Characterized by having a comb-shaped electrode made of a base alloy film
Surface acoustic wave device. 17. A method for manufacturing the surface acoustic wave device according to claim 4.
A surface acoustic wave device manufactured by using the manufacturing method, 36 ° rotation Y-cut lithium tantalate single crystal piezoelectric
(111) single crystal aluminum or
Having a comb-shaped electrode made of an aluminum-based alloy film
Characteristic surface acoustic wave device. 18. A method for manufacturing a surface acoustic wave device according to claim 5.
A surface acoustic wave device manufactured by using the manufacturing method, 128 ° rotation Y-cut lithium niobate single crystal piezoelectric
(111) single crystal aluminum or
Having a comb-shaped electrode made of an aluminum-based alloy film
Characteristic surface acoustic wave device. 19. The surface acoustic wave device according to claim 6,
Manufacturing using manufacturing method A surface acoustic wave device, The 41 ° rotation Y-cut lithium niobate single crystal piezoelectric substrate
(111) single crystal aluminum or aluminum
It has a comb-shaped electrode made of aluminium-based alloy film.
Surface acoustic wave device. 20. Manufacturing of the surface acoustic wave device according to claim 7.
A surface acoustic wave device manufactured by using the manufacturing method, The 64 ° rotation Y-cut lithium niobate single crystal piezoelectric substrate
(111) single crystal aluminum or aluminum
It has a comb-shaped electrode made of aluminium-based alloy film.
Surface acoustic wave device.