JPH05267971A - Surface acoustic wave filter and its manufacture - Google Patents

Abstract

PURPOSE:To obtain the surface acoustic wave filter for preventing disconnection of a conductor pattern, and also, detecting easily a short circuit by connecting a repeating electrode to a test electrode through a conductor, and also, connecting all ground comb teeth elements belonging to the same comb teeth electrode train through a conductor. CONSTITUTION:All conductors 16 between the same comb teeth electrode trains 2 are connected to a test electrode 42 through a conductor 41, and in all ground comb teeth elements 25 belonging to the same comb teeth electrode trains 2, the tip or the root part of the comb teeth 23 is connected through a conductor 43. In such a way, resistance between a ground electrode 17 and an input electrode 13, an output electrode 15 or a test electrode 42 is measured and a short circuit can be detected easily. Also, by short-circuiting conductors 12, 14 for connecting the ground comb teeth element 25 in a state of a wafer, the input electrode 13, the output electrode 15 and the test electrode 42 by a conductor provided in the outside of a chip forming area, disconnection caused by a pyroelectric effect can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cascaded surface acoustic wave filter capable of achieving a large stopband attenuation and a method for manufacturing the same.

A filter element utilizing surface acoustic waves is considered to be an indispensable circuit component for realizing a compact and lightweight mobile communication device. However, the piezoelectric substrate used for the surface acoustic wave filter has a pyroelectric effect, and the conductor pattern formed on the substrate is often broken.

Further, the surface acoustic wave filter is composed of fine comb-teeth-shaped conductor patterns, so that a short circuit between the conductor patterns easily occurs. Therefore, it is desired to develop a surface acoustic wave filter that can prevent the conductor pattern from breaking and can easily detect a short circuit, and a manufacturing method thereof.

[0004]

2. Description of the Related Art FIG. 3 is a plan view showing a conventional surface acoustic wave filter chip, FIG. 4 is a side sectional view showing a completed surface acoustic wave filter chip, and FIG. 5 is another conventional surface acoustic wave filter chip. FIG.

In FIG. 3, a chip 1 of a conventional surface acoustic wave filter has a plurality of (two rows in the figure) comb-teeth electrode rows 2 formed on a piezoelectric substrate 11, and each comb-teeth electrode row 2 has a plurality of input combs. The tooth electrodes 21 and the output comb electrodes 22 are arranged alternately in the propagation direction of the surface acoustic wave.

The input comb-teeth electrode 21 is composed of a pair of excitation comb-teeth elements 24 and ground comb-teeth elements 25 in which the comb-teeth 23 are fitted between the other comb-teeth 23, and the output comb-teeth electrode 22 is formed by the comb-teeth 23. Is provided with a pair of vibration-receiving comb-tooth elements 26 and grounding comb-tooth elements 25 which are fitted between the mating comb-teeth 23 of each other.

On the outside of the comb-teeth electrode array 2 on the input side, all the excitation comb-teeth elements 24 are connected to the input electrodes via the conductor 12 having a relatively wide width.
Outside the comb-teeth electrode array 2 on the output side, all the vibration-receiving comb-teeth elements 26 are connected to the output electrode 15 via the conductor 14 having a relatively wide width.

Further, between the comb-teeth electrode rows 2, an exciting comb-teeth element 24 and a receiving comb-teeth element 26, which are adjacent to each other and have opposite back surfaces, are connected via a conductor 16, and all the ground comb-teeth elements 25 are comb-shaped. It is connected to a dedicated ground electrode 17 arranged between the tooth electrode rows 2 and outside.

The chip 1 of the surface acoustic wave filter is die-bonded to the package 3 made of ceramic as shown in FIG. 4, and the input electrode 13 and the output electrode 15 of the chip 1 are
The ground electrode 17 is connected to the conductor 32 on the package 3 via the Al wire 31.

Further, in FIG. 5, another conventional surface acoustic wave filter chip 1 has a plurality of comb-teeth electrode rows 2 formed on a piezoelectric substrate 11, and each comb-teeth electrode row 2 has a plurality of input comb-teeth electrodes. 21 and the output comb-teeth electrode 22 are alternately arranged in the propagation direction of the surface acoustic wave.

The input comb-teeth electrode 21 is composed of a pair of exciting comb-teeth elements 24 and ground comb-teeth elements 25 in which the comb-teeth 23 are fitted between the mating comb-teeth 23 of each other. Is provided with a pair of vibration-receiving comb-tooth elements 26 and grounding comb-tooth elements 25 which are fitted between the mating comb-teeth 23 of each other.

On the outside of the comb-teeth electrode array 2 on the input side, all the excitation comb-teeth elements 24 are connected to the input electrodes via the conductor 12 having a relatively wide width.
Outside the comb-teeth electrode array 2 on the output side, all the vibration-receiving comb-teeth elements 26 are connected to the output electrode 15 via the conductor 14 having a relatively wide width.

Between the input-side and output-side comb-teeth electrode rows 2, an exciting comb-tooth element 24 and a receiving comb-teeth element 26, which are adjacent to each other and have opposite back surfaces, are connected via a conductor 16, and a grounding comb having adjacent and back-to-back elements is connected. Unlike the surface acoustic wave filter, the tooth element 25 is a conductor.
It is connected through 18.

The grounding comb-tooth element 25 paired with the exciting comb-tooth element 24 and the receiving comb-tooth element 26, which are connected to each other through the conductor 16 between the comb-tooth electrode rows 2, are both outside the comb-tooth electrode row 2. Are connected to the dedicated ground electrode 17 which is located independently of each other.

The surface acoustic wave filter chip 1 is also die-bonded to the ceramic package 3 as shown in FIG. 4, and the input electrode 13, the output electrode 15, and the ground electrode 17 are formed on the package 3 via the Al wire 31. Connected to the connected conductor 32.

That is, when a signal is input to the input electrode 13, the input comb-teeth electrode 21 belonging to the comb-teeth electrode array 2 on the input side generates a surface acoustic wave, and the output comb-teeth electrode 22 sandwiching the input comb-teeth electrode 21. Converts the surface acoustic wave into an electric signal and inputs the electric signal to the comb-teeth electrode array 2 on the output side via the conductor 16.

In the comb-teeth electrode array 2 on the output side, the input comb-teeth electrode 21 to which a signal is input via the conductor 16 generates a surface acoustic wave, and the output comb-teeth electrodes 22 on both sides of the input comb-teeth electrode 21. Receives the surface acoustic wave, converts it into an electric signal, and outputs the signal from the output electrode 15.

Since the surface acoustic wave filter in which the plurality of input comb-teeth electrodes 21 and the output comb-teeth electrodes 22 are cascade-connected in this way has a large amount of attenuation in the stop band, it is important to reduce the size and weight of the mobile communication device. It is widely used as an indispensable filter element in the above.

[0019]

However, LiTaO ₃ or the like used as a piezoelectric substrate in a surface acoustic wave filter is known as a pyroelectric material having a pyroelectric effect and is generated on the surface of the piezoelectric substrate by the pyroelectric effect. The high voltage often breaks the fine comb-teeth electrodes formed on the surface.

In addition, the width of the comb teeth forming the input comb-teeth electrode and the output comb-teeth electrode is 1 to 2 μm, and the distance between adjacent comb teeth is 1 as well.
~ 2 μm. Although such fine comb teeth are easily short-circuited, there is a problem that the conventional surface acoustic wave filter cannot be inspected in a chip state.

An object of the present invention is to provide a surface acoustic wave filter which can prevent disconnection of a conductor pattern and can easily detect a short circuit, and a method of manufacturing the same.

[0022]

FIG. 1 is a plan view showing a surface acoustic wave filter according to the present invention. Note that the same object is denoted by the same symbol throughout the drawings.

The above problem is solved by a plurality of input comb-teeth electrodes in which the comb teeth of the excitation comb-teeth element 24 are fitted between the comb teeth of the ground comb-teeth element 25.
21 and a plurality of output comb-teeth electrodes 22 in which the comb-teeth of the vibration-receiving comb-teeth element 26 are fitted between the comb-teeth of the ground comb-teeth element 25, a plurality of combs arranged alternately in the propagation direction of the surface acoustic wave. The tooth electrode rows 2 are formed in parallel on the piezoelectric substrate 11, and the conductors 16 are provided between the comb tooth electrode rows 2.
Connect the excitation comb-tooth element 24 and the vibration-receiving comb-tooth element 26 which are adjacent to each other,
Outside the comb-teeth electrode array 2, all the excitation comb-teeth elements 24 are connected to the input electrode 13 via the conductor 12, and all the reception comb-teeth elements 26 are connected to the output electrode 15 via the conductor 14. In the surface acoustic wave filter, all the conductors 16 formed between the same comb-teeth electrode row 2 are connected to the test electrode 42 via the conductor 41, and all the ground comb-teeth elements 25 belonging to the same comb-teeth electrode row 2 are connected. This is achieved by the surface acoustic wave filter of the present invention which is connected via the conductor 43.

[0024]

In FIG. 1, all the relay electrodes formed between the same comb-teeth electrode rows are connected to the test electrodes via conductors, and all the ground comb-teeth elements belonging to the same comb-teeth electrode row are connected via conductors. By connecting, the ground electrode and the input electrode,
A short circuit can be easily detected by measuring the resistance between the output electrode or the test electrode. Further, for example, in the state of a wafer, the conductor, the input electrode, the output electrode, and the test electrode, which are connected to the ground comb-tooth element, are short-circuited by the conductor provided outside the chip formation region, so that the disconnection due to the pyroelectric effect can be prevented. That is, it is possible to realize a surface acoustic wave filter and a method for manufacturing the same that can prevent disconnection of the conductor pattern and can easily detect a short circuit.

[0025]

Embodiments of the present invention will be described below with reference to the accompanying drawings. 2 is a plan view showing another embodiment of the present invention.

In FIG. 1, a surface acoustic wave filter according to the present invention has a plurality (two rows in the figure) of comb-teeth electrode rows 2 formed on a piezoelectric substrate 11, and each comb-teeth electrode row 2 has a plurality of input comb-teeth. The electrodes 21 and the output comb-teeth electrodes 22 are arranged alternately in the surface acoustic wave propagation direction.

The input comb-teeth electrode 21 is composed of a pair of exciting comb-teeth elements 24 and ground comb-teeth elements 25 in which the comb-teeth 23 are fitted between the mating comb-teeth 23 of each other. Is provided with a pair of vibration-receiving comb-tooth elements 26 and grounding comb-tooth elements 25 which are fitted between the mating comb-teeth 23 of each other.

On the outside of the comb-teeth electrode array 2 on the input side, all the excitation comb-teeth elements 24 are connected to the input electrodes via the conductor 12 having a relatively wide width.
Outside the comb-teeth electrode array 2 on the output side, all the vibration-receiving comb-teeth elements 26 are connected to the output electrode 15 via the conductor 14 having a relatively wide width.

In addition, between the comb-teeth electrode rows 2, the excitation comb-teeth element 24 and the reception comb-teeth element 26, which are adjacent to each other and whose rear faces face each other, are connected through the conductor 16, and the excitation comb-teeth element 24 and the reception comb-teeth element 26 are connected. The grounding comb-teeth element 25 paired with
It is connected to the.

Unlike the conventional surface acoustic wave filter, all the conductors 16 between the same comb-teeth electrode array 2 are connected to the test electrode 42 via the conductor 41.
All grounded comb-tooth elements connected to the same comb-tooth electrode array 2
25, the tips or roots of the comb teeth 23 are connected via a conductor 43.

When a plurality of independent conductor patterns are formed on the piezoelectric substrate, electric charges generated by the pyroelectric effect are accumulated in each conductor pattern, and when the electric charges are discharged due to a short circuit between adjacent conductor patterns or the like, fine charges are generated. A large current flows in the conductor pattern, causing disconnection.

Therefore, the surface acoustic wave filter according to the present invention is used as a means for preventing disconnection due to the pyroelectric effect in the state of a wafer, the conductor 43 connecting the ground comb element 25, the input electrode 13, the output electrode 15 and the test. The electrodes 42 are connected by conductors 44 outside the chip formation region.

The conductor 44 formed outside the chip formation region is cut off when the wafer is diced to individualize the surface acoustic wave filter. Therefore, the ground electrode 17 and the input electrode 1
3. The resistance between the output electrode 15 or the test electrode 42 can be measured to easily detect a short circuit.

In this way, all the relay electrodes formed between the same comb tooth electrode rows are connected to the test electrodes via conductors, and all the ground comb tooth elements belonging to the same comb tooth electrode row are connected via conductors. By connecting, the ground electrode and the input electrode,
A short circuit can be easily detected by measuring the resistance between the output electrode or the test electrode.

Further, in the state of the wafer, the conductor for connecting the ground comb-teeth element, the input electrode, the output electrode and the test electrode are
By short-circuiting with a conductor provided outside the chip formation region, disconnection due to the pyroelectric effect can be prevented. That is, it is possible to realize a surface acoustic wave filter and a method for manufacturing the same that can prevent disconnection of the conductor pattern and can easily detect a short circuit.

In FIG. 2, another surface acoustic wave filter according to the present invention has a plurality (two rows in the figure) of comb-teeth electrode rows 2 formed on a piezoelectric substrate 11, and each comb-teeth electrode row 2 has a plurality of inputs. The comb-teeth electrodes 21 and the output comb-teeth electrodes 22 are alternately arranged in the propagation direction of the surface acoustic wave.

The input comb-teeth electrode 21 is composed of a pair of excitation comb-teeth elements 24 and ground comb-teeth elements 25 in which the comb-teeth 23 are fitted between the mating comb-teeth 23 of each other. Is provided with a pair of vibration-receiving comb-tooth elements 26 and grounding comb-tooth elements 25 which are fitted between the mating comb-teeth 23 of each other.

On the outside of the comb-teeth electrode array 2 on the input side, all the excitation comb-teeth elements 24 are connected to the input electrodes via the conductor 12 having a relatively wide width.
Outside the comb-teeth electrode array 2 on the output side, all the vibration-receiving comb-teeth elements 26 are connected to the output electrode 15 via the conductor 14 having a relatively wide width.

Unlike the above-mentioned embodiment, the ground comb-tooth element 25 is adjacent between the comb-teeth electrode rows 2 on the input side and the output side, and the back faces are opposed to each other.
Are also connected via the conductor 18, and the excitation comb-tooth element 24 and the vibration-receiving comb-tooth element 26, which are adjacent to each other and face each other on the back surface, are also connected via the conductor 16.

The ground comb-tooth element 25 paired with the excitation comb-tooth element 24 and the vibration-receiving comb-tooth element 26 connected to each other through the conductor 16 between the comb-tooth electrode rows 2 are both outside the comb-tooth electrode row 2. Are connected to the dedicated ground electrode 17 which is located independently of each other.

The ground electrode 17 connected to the ground comb-tooth element 25 belonging to the input-side comb-teeth electrode array 2 is connected to the conductor 12 via the auxiliary conductor 45, and the ground electrode 17 belonging to the output-side comb-teeth electrode array 2. The ground electrode 17 to which the tooth element 25 is connected is a conductor via the auxiliary conductor 45.
Connected to 14.

In this way, the auxiliary conductor 45 and the conductor 12 or the conductor
By connecting the ground electrode 17 to the input electrode 13 or the output electrode 15 via 14, all the input comb-teeth electrodes 21 and the output comb-teeth electrodes 22 constituting the comb-teeth electrode array 2 are input electrodes 13 or output electrodes 15. Connected to.

As a result, by measuring the resistance between the input electrode 13 and the output electrode 15 when detecting a short circuit between the comb-tooth elements in the state of the chip, the input comb-tooth electrode 21 and the output comb-shaped electrode 21 connected by the conductor 18 are measured. If the tooth electrodes 22 are short-circuited at the same time, they can be easily detected.

The ground electrode 17 and the conductor 12 or the conductor 14
The width of the auxiliary conductor 45 connecting between the conductors 12 and 14 is extremely narrow as compared with the width of the conductors 12 and 14, and after assembly is completed, a high voltage is applied between the input electrode 13 or the output electrode 15 and the ground electrode 17 to easily fuse the conductors. You can refuse.

[0045]

As described above, according to the present invention, it is possible to provide a surface acoustic wave filter which prevents disconnection of a conductor pattern and is easy to detect a short circuit, and a manufacturing method thereof.

[Brief description of drawings]

FIG. 1 is a plan view showing a surface acoustic wave filter according to the present invention.

FIG. 2 is a plan view showing another embodiment of the present invention.

FIG. 3 is a plan view showing a chip of a conventional surface acoustic wave filter.

FIG. 4 is a side sectional view showing a completed surface acoustic wave filter.

FIG. 5 is a plan view showing a chip of another conventional surface acoustic wave filter.

[Explanation of symbols] 2 Comb-tooth electrode array 11 Piezoelectric substrate 12, 14 Conductor 13 Input electrode 15 Output electrode 16, 18 Conductor 17 Ground electrode 21 Input comb-tooth electrode 22 Output comb-tooth electrode 23 Comb tooth 24 Excitation comb-tooth element 25 Ground Comb element 26 Vibration receiving comb element 41, 43, 44 Conductor 42 Test electrode 45 Auxiliary conductor

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Sumio Yamada 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited Ltd. 72) Inventor Yoshimi Sakai, 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (5)

[Claims] 1. A comb-teeth element for exciting a comb-teeth element (24) is grounded.
A plurality of input comb-teeth electrodes (21) fitted between the comb teeth of (25)
And a plurality of output comb-teeth electrodes (22) in which the comb-teeth of the vibration-receiving comb-teeth element (26) are fitted between the comb-teeth of the ground comb-teeth element (25) are arranged alternately in the propagation direction of the surface acoustic wave. Multiple comb-teeth electrode arrays
(2) is formed in parallel on the piezoelectric substrate (11), and the exciting comb tooth element (24) and the receiving comb tooth element (26) that are adjacent to each other by the conductor (16) between the comb tooth electrode rows (2) To connect the comb-teeth electrode array
Outside the (2), all of the excitation comb tooth elements are connected via the conductor (12).
In the surface acoustic wave filter in which (24) is connected to the input electrode (13) and all the receiving comb tooth elements (26) are connected to the output electrode (15) through the conductor (14), the same comb teeth are used. All the conductors (16) formed between the electrode rows (2) are connected to the test electrode (42) via the conductor (41), and all ground comb tooth elements belonging to the same comb tooth electrode row (2) are connected. (25) to conductor (4
A surface acoustic wave filter characterized by being connected via 3). 2. A conductor (43) for connecting a ground comb-tooth element (25) in a wafer state as means for preventing disconnection due to a pyroelectric effect in the method of manufacturing a surface acoustic wave filter according to claim 1. A method for manufacturing a surface acoustic wave filter, characterized in that the input electrode (13), the output electrode (15) and the test electrode (42) are short-circuited by a conductor (44) provided outside the chip formation region. 3. A method of manufacturing a surface acoustic wave filter according to claim 1, wherein as a means for detecting a short circuit between the comb tooth elements, a wafer is diced to separate the surface acoustic wave filters and then a ground comb tooth element ( 25) connected to the ground electrode
(17) and input electrode (13), output electrode (15) or test electrode (4
2) A method of manufacturing a surface acoustic wave filter, characterized by measuring the resistance between the surface acoustic wave filter and the surface acoustic wave filter. 4. The comb teeth of the excitation comb tooth element (24) are grounded.
A plurality of input comb-teeth electrodes (21) fitted between the comb teeth of (25)
And a plurality of output comb-teeth electrodes (22) in which the comb-teeth of the vibration-receiving comb-teeth element (26) are fitted between the comb-teeth of the ground comb-teeth element (25) are arranged alternately in the propagation direction of the surface acoustic wave. Multiple comb-teeth electrode arrays
(2) are formed in parallel on the piezoelectric substrate (11), and the adjacent comb-teeth element (25) is connected between the comb-teeth electrode rows (2) through the conductor (18) and the conductor ( The excitation comb-tooth element (24) and the receiving comb-tooth element (26) are connected via the (16), and all the excitation comb-teeth are connected via the conductor (12) outside the comb-tooth electrode array (2). In the production of a surface acoustic wave filter in which the element (24) is connected to the input electrode (13), and all the receiving comb-teeth elements (26) are connected to the output electrode (15) via the conductor (14), Connect the ground electrode (17), which is connected to the ground comb-tooth element (25) located outside the comb-teeth electrode array (2), and the conductors (12, 14) with the auxiliary conductor (45). A method of manufacturing a surface acoustic wave filter, which comprises measuring the resistance between the electrode (13) and the output electrode (15). 5. The method for manufacturing a surface acoustic wave filter according to claim 4, wherein the auxiliary conductor (45) is made thinner than the conductors (12, 14), and after the assembly of the surface acoustic wave filter is completed, the input electrode (13 ) Or a high voltage is applied between the output electrode (15) and the ground electrode (17) to fuse the auxiliary conductor (45).