JPH08298426A - Surface acoustic wave device and its manufacture - Google Patents

Abstract

PURPOSE: To obtain a surface acoustic wave device whose go or no-go is easily discriminated even in the case of the high frequency use device by providing an acceptance discrimination pattern to the surface of a piezoelectric substrate. CONSTITUTION: This device is provided with a piezoelectric substrate 1, interdigital electrodes 2 provided on the surface of the piezoelectric substrate 1, input output electrodes 3, 4 connected to the interdigital electrodes 2 and provided on the piezoelectric substrate 1 and an acceptance discrimination pattern 6 on the surface of the piezoelectric substrate 1.

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 and a method for manufacturing the same.

[0002]

2. Description of the Related Art A conventional surface acoustic wave device is provided with a comb-shaped electrode, an input / output electrode, and a reflector, and the frequency characteristic is measured from the input / output electrode for each device.

[0003]

Among the above-mentioned conventional ones, in the case of a high frequency, when the sensing electrode is brought into contact with the input / output electrode for measuring the frequency characteristic, the impedance of this sensing electrode is added. Then, there is a problem that the true frequency characteristic cannot be measured.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a surface acoustic wave device which can easily determine pass / fail even for high frequencies.

[0005]

In order to achieve this object, the present invention provides a piezoelectric substrate, a comb-shaped electrode provided on the surface of the piezoelectric substrate, and the piezoelectric substrate connected to the comb-shaped electrode. With the input / output electrodes provided above,
A pass / fail judgment pattern is provided on the surface of the piezoelectric substrate.

[0006]

With the above structure, the quality determination pattern is provided separately from the comb-shaped electrode, and the quality of the frequency characteristics of the surface acoustic wave device is determined by measuring the resistance value of the quality determination pattern. Therefore, it is possible to easily perform the quality inspection even for high frequency. That is, the frequency characteristic is determined substantially uniquely by the pattern (width and thickness) of the comb-shaped electrode, and the resistance value of the pass / fail judgment pattern formed at the same time as this comb-shaped electrode is also determined by the width and thickness. Therefore, the quality of the frequency characteristic can be determined from this resistance value.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In FIG. 1, reference numeral 1 is a piezoelectric substrate made of lithium tantalate or the like, on the surface of which a comb-shaped electrode 2 made of aluminum or its alloy, input / output electrodes 3 and 4, a reflector 5 are provided.
Is provided. The surface of the piezoelectric substrate 1 is also provided with a linear pass / fail judgment pattern 6 made of aluminum or its alloy. The pass / fail judgment pattern 6 is formed by photolithography at the same time as other electrodes, and its line width is 1 as in the comb-shaped electrode 2.
The thickness is also 0.2 μm. Both ends of this pass / fail judgment pattern have electrodes 6 with a large area.
a and 6b, the detection electrode 7 is brought into contact with the electrodes 6a and 6b as shown in FIG.
Then, the resistance value of the pass / fail judgment pattern 6 is measured, then the comparison circuit 9 compares it with the reference resistance value, and the control circuit 10 judges pass / fail. If the product is defective, marking is performed on the piezoelectric substrate 1.

That is, the frequency characteristic is determined substantially uniquely by the pattern (width and thickness) of the comb electrode 2.
Since the resistance value of the pass / fail judgment pattern 6 formed at the same time as the comb-shaped electrode 2 is also determined by the width and the thickness, the pass / fail judgment of the frequency characteristic can be performed from this resistance value.

FIG. 3 shows another embodiment. In this embodiment, the central portion of the reflector 5 on the right side is divided, and one pattern is used to form a pass / fail judgment pattern 6.

FIG. 4 also shows another embodiment. In this embodiment, the pass / fail judgment pattern 6 is formed by using the three patterns of the reflector 5 on the right side as meandering patterns.

FIG. 5 also shows another embodiment. In this embodiment, the entire pattern of the reflector 5 on the right side is a meandering pattern, and one end thereof is connected to one of the comb-shaped electrodes 2 via the output electrode 4. , The other end is connected to the other end of the comb-shaped electrode 2 via the input electrode 3 to form the pass / fail judgment pattern 6.

FIG. 6 also shows another embodiment, in which the comb-shaped electrode 2 is 2
This is a type in which a pass / fail judgment pattern 6 having a meandering pattern is formed outside the left comb-shaped electrode.

FIG. 7 also shows another embodiment. In this embodiment, linear dummy electrodes 11 are provided on both sides of the linear quality determination pattern 6. That is, the pass / fail judgment pattern 6 is formed at the same time as the comb-shaped electrode 2 as described above. However, the comb-shaped electrode 2 has a plurality of patterns on the left and right, and etching is performed under the same conditions as described above.
The dummy electrodes 11 are provided on both sides of the pass / fail judgment pattern 6.

FIG. 8 also shows another embodiment, in which one end of the pass / fail judgment pattern 6 is connected to the input electrode 3.

FIG. 9 shows an example in which a plurality of chip patterns are formed on a wafer. In this embodiment, the input / output electrodes 3,
The pass / fail judgment pattern 6 connected to 4 is expanded outward so as to surround the reflector 5, and the broken line is a cutting line for forming each chip. That is, if the frequency characteristic pass / fail judgment is performed by measuring the resistance value of each chip on the wafer, and then cut at the broken line portion, the pass / fail judgment pattern 6 is cut.

In FIG. 10, the resistance value shown in FIG. 9 is measured on the wafer 12, and at the same time, the sheet resistance of the rectangular pattern 13 provided in the central portion of the wafer 12 is measured to calculate the film thickness. -ing

In FIG. 11, three rectangular patterns 13 are concentrically provided. That is, since the film thickness varies depending on the circumferential direction, three concentric circles are measured.

[0018]

As described above, according to the present invention, the piezoelectric substrate, the comb-shaped electrode provided on the surface of the piezoelectric substrate, and the input / output electrode connected to the comb-shaped electrode and provided on the piezoelectric substrate. And a pass / fail judgment pattern is provided on the surface of the piezoelectric substrate.

With the above arrangement, the quality determination pattern is provided separately from the comb-shaped electrodes, and the quality of the frequency characteristics of the surface acoustic wave device is determined by measuring the resistance value of the quality determination pattern. Therefore, the quality inspection can be easily performed even for high frequency. That is, the frequency characteristic is determined substantially uniquely by the pattern (width and thickness) of the comb-shaped electrode, and the resistance value of the pass / fail judgment pattern formed at the same time as this comb-shaped electrode is also determined by the width and thickness. Therefore, the quality of the frequency characteristic can be determined from this resistance value.

Further, in the conventional method, an expensive machine such as a network analyzer is required to measure the frequency characteristic, but in the present invention, the resistance meter is sufficient, so the equipment cost is low and the measuring speed is also high. Get faster

As another effect, when the comb-shaped electrodes are connected by a pass / fail judgment pattern as shown in FIG. 5 or FIG. 9, and if a short circuit occurs between the comb-shaped electrodes, the resistance value between them becomes extremely small. Moreover, not only the deviation of the center frequency but also a short circuit can be detected. Furthermore, since the inter-comb electrodes are terminated with a certain resistance value, it is possible to prevent the comb electrodes from being destroyed by pyroelectricity or static electricity.

In the case of FIG. 9, since the comb-shaped electrodes are opened when the chip is cut, the characteristics are not affected. In the case of FIG. 5, if the termination is made with a resistance value much larger than the impedance of the comb-shaped electrode, the characteristics are hardly affected. In this case, the termination is made with a certain resistance value even in the finished product. Therefore, it is possible to prevent the comb-shaped electrodes from being broken due to pyroelectricity that occurs in a soldering process or the like.

[Brief description of drawings]

FIG. 1 is a plan view of a surface acoustic wave device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram for measuring a resistance value according to an embodiment of the present invention.

FIG. 3 is a plan view of a surface acoustic wave device according to another embodiment of the present invention.

FIG. 4 is a plan view of a surface acoustic wave device according to another embodiment of the present invention.

FIG. 5 is a plan view of a surface acoustic wave device according to another embodiment of the present invention.

FIG. 6 is a plan view of a surface acoustic wave device according to another embodiment of the present invention.

FIG. 7 is a plan view of a surface acoustic wave device according to another embodiment of the present invention.

FIG. 8 is a plan view of a surface acoustic wave device according to another embodiment of the present invention.

FIG. 9 is a plan view of a surface acoustic wave device according to another embodiment of the present invention.

FIG. 10 is a plan view of a wafer according to another embodiment of the present invention.

FIG. 11 is a plan view of a wafer according to another embodiment of the present invention.

[Explanation of symbols]

 1 piezoelectric substrate 2 comb-shaped electrode 3 input electrode 4 output electrode 5 reflector 6 pass / fail judgment pattern

Claims (14)

[Claims] 1. A piezoelectric substrate, a comb-shaped electrode provided on a surface of the piezoelectric substrate, and an input / output electrode connected to the comb-shaped electrode and provided on the piezoelectric substrate. A surface acoustic wave device in which a pass / fail judgment pattern is provided on the surface. 2. The surface acoustic wave device according to claim 1, wherein the pass / fail judgment pattern is formed to have substantially the same line width as the comb electrode. 3. The surface acoustic wave device according to claim 1, wherein the pass / fail judgment pattern is provided in a state where the comb-shaped electrode and the input / output electrode are not connected. 4. The surface acoustic wave device according to claim 1, wherein at least one end of the pass / fail judgment pattern is connected to one of the input / output electrodes. 5. The surface acoustic wave device according to claim 1, wherein reflectors are provided on both sides of the comb-shaped electrode, and at least one of the reflectors is divided to form a pass / fail judgment pattern. 6. A reflector is provided on both sides of a comb-shaped electrode, and a part or all of one reflector is formed in a meandering shape, one end of the meandering shape being one of the comb-shaped electrodes and the other end being the other. The surface acoustic wave device according to claim 1, which is connected to the. 7. The surface acoustic wave device according to claim 1, wherein dummy electrodes are provided on both sides of the pass / fail judgment pattern. 8. A resistance value of the pass / fail judgment pattern is measured by bringing the detection electrode into contact with a pass / fail judgment pattern provided on the surface of the piezoelectric substrate independently of the comb-shaped electrode, and the measured resistance is measured. A method for manufacturing a surface acoustic wave device, wherein a quality is determined by comparing a value and a reference resistance value. 9. The method of manufacturing a surface acoustic wave device according to claim 8, wherein the pass / fail judgment pattern arranged in the vicinity of the cutting line is connected to each comb-shaped electrode. 10. The method of manufacturing a surface acoustic wave device according to claim 9, wherein the pass / fail judgment pattern is cut at the same time when the chip is cut. 11. A method for measuring a film thickness of at least one electrode is provided separately from a chip on a wafer, and a reference resistance value is determined by the film thickness.
A method for manufacturing the surface acoustic wave device according to claim 1. 12. A plurality of patterns for measuring an electrode film thickness are formed from a center of a wafer to a peripheral part thereof, and a chip on each concentric circle has a reference resistance value determined by each film thickness. The method for manufacturing a surface acoustic wave device according to claim 8. 13. The pattern for measuring the electrode film thickness is one chip or a plurality of chips of the entire surface electrode,
The method for manufacturing a surface acoustic wave device according to claim 11, wherein the electrode film thickness is measured by measuring the sheet resistance. 14. The pattern for measuring the electrode film thickness is one chip or a plurality of chips of the entire surface electrode,
The method for manufacturing a surface acoustic wave device according to claim 11 or 12, wherein the fluorescent X-ray emitted by applying X-ray is calibrated to measure the electrode film thickness.