JPH0818374A - Surface wave device and its manufacture - Google Patents

Abstract

PURPOSE:To form the surface wave device which has specific frequency characteristics by oxidizing or nitrifying the surfaces of comb-line electrodes on a piezoelectric substrate and adjusting the mass of the interdigital electrodes. CONSTITUTION:The interdigital electrodes 2 are formed of aluminum on the piezoelectric substrate 1 of crystal of the surface wave device. This substrate 1 is set on a substrate stage 6 and the frequency characteristics of the substrate 1 are detected in a vacuum state by using a probe 5 for frequency characteristic detection and a frequency characteristic detection device 7. When the frequency is high, it is decided that the thickness of the electrodes 2 is thin, the substrate 1 is mounted on a substrate stage 11, and while oxygen or nitrogen is fed through a gas intake 14, the laser light from a laser 12 sweeps the substrate 1 for a necessary time based upon the detected frequency. Then the surfaces of the electrodes 2 are oxidized or nitrified and the thickness of the electrodes 2 reaches necessary thickness because of the oxidized layers or nitrified layers, thereby obtaining the piezoelectric substrate of the surface wave device which has the specific frequency characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a surface wave device used in mobile communication equipment and the like.

[0002]

2. Description of the Related Art In recent years, surface wave devices have been described in "New Ceramics" (1993) No. It has been developed as an indispensable electronic component for mobile communication and the like as described on pages 35-42.

As a conventional example thereof, a schematic perspective view of a surface acoustic wave device is shown in FIG. 4 and a flow chart of a manufacturing process is shown in FIG.

In the surface acoustic wave device manufactured by the process shown in FIG. 5, the center frequency F0 is the pitch λ0 of the comb electrodes.
And the elastic surface velocity Vs of the piezoelectric substrate are determined by (Equation 1) and function as a frequency filter.

[0005]

[Equation 1]

[0006]

However, as the thickness of the comb-shaped electrode increases, the frequency characteristics are affected by the effect of its weight. For example, as shown in FIG. 6, the relationship between the film thickness of the aluminum comb-shaped electrode and the obtained center frequency when the aluminum comb-shaped electrodes are formed in the same pattern shape on the piezoelectric substrate of quartz of the same lot is shown. Behaves differently.

From FIG. 6, for example, a center frequency of 15300
In order to create a surface acoustic wave device having a frequency characteristic of 0 kHz ± 50 kHz, the thickness of the aluminum comb-shaped electrode should be 5
It is necessary to control the film thickness to 300 ± 50 Å (± about 1% with respect to the absolute film thickness), and it is necessary to control the film thickness with high accuracy when forming the electrode.

However, at present, there are various film thickness control methods at the time of film formation, but the film thickness reproducibility of each lot is ± 5% within the limit that can be stabilized in production, and the accuracy of the obtained absolute film thickness. Is about ± 5%, the required high accuracy (± 1%)
Film thickness control is impossible.

As an example of the film thickness control method, a film thickness control method using a crystal oscillator will be described below.

In the crystal oscillator system, when the particles sputtered from the target adhere to the surface of the crystal oscillator installed near the substrate, the resonance frequency of the crystal oscillator changes, so this change is monitored and adhered. This is a method of controlling the film thickness by calculating the film thickness of the film and obtaining the correlation between the film thickness obtained from the resonance frequency and the film thickness on the substrate. However, this control method has the following problems.

1. Since the scattering distribution of sputtered particles from the target changes with time, the correlation between the film thickness at the installation location of the crystal oscillator and the film thickness at the substrate does not match.

2. The crystal oscillator is exposed to plasma, receives an electron impact, and its temperature rises, causing a shift in frequency characteristics.

3. When the films are stacked thickly, peeling occurs, so that the change in the resonance frequency is disturbed. Due to the above problems, it is difficult to realize highly accurate film thickness control in the crystal oscillator method, and there are similar problems in other film thickness control methods.

Due to the above problems, it is very difficult to manufacture a surface acoustic wave device having a predetermined frequency characteristic. In the step (9) frequency characteristic evaluation of FIG. 5, the probe is brought into contact with the comb-shaped electrode to detect the frequency characteristic of the surface acoustic wave device. I was there. 2. Alternatively, after the step (7) of printing the sound absorbing agent in FIG. 5, the frequency characteristics of the large number of surface acoustic wave devices are detected by the probe with the large number of surface acoustic wave devices formed on the piezoelectric substrate.
If the ratio of those having a predetermined frequency characteristic is high, the process is post-processed, and if the ratio is low, the device is defective. Therefore, there is a problem that the non-defective rate is low.

In view of the above problems, it is an object of the present invention to provide a method of manufacturing a surface acoustic wave device capable of obtaining a high performance surface acoustic wave device having a predetermined frequency characteristic with a high yield rate.

[0016]

In order to solve the above problems, the present invention constitutes a surface wave device by oxidizing or nitriding the surface of a comb-shaped electrode provided on a piezoelectric substrate and providing an oxide layer or a nitride layer. .

Further, a manufacturing method having the following steps is adopted. (1) Step of forming a comb-shaped electrode on the piezoelectric substrate (2) Step of detecting the frequency characteristic of the surface acoustic wave device after the formation of the comb-shaped electrode (3) According to the detection result of the step (2), oxygen or nitrogen Laser sweeping on the comb-shaped electrode in an atmosphere, or oxidizing or nitriding the comb-shaped electrode with plasma containing oxygen or nitrogen, or anodizing the comb-shaped electrode by a wet method to oxidize or nitride the surface of the comb-shaped electrode. In the step (2), when the frequency characteristic of the surface acoustic wave device reaches a predetermined characteristic, the step of oxidizing or nitriding the step (3) is finished.

[0018]

According to the present invention, if the surface wave device has a characteristic higher than a predetermined center frequency by the above means, the film thickness of the comb electrode is smaller than the predetermined film thickness. Because it is light.

Therefore, the surface of the comb-shaped electrode is oxidized or nitrided by sweeping on the comb-shaped electrode with a laser in an atmosphere containing oxygen or nitrogen. Thus, for example, if the material of the comb-shaped electrode is aluminum, the surface layer becomes aluminum oxide or aluminum nitride, and the mass of the comb-shaped electrode can be increased. By increasing the mass, the center frequency becomes lower and a predetermined frequency characteristic can be obtained.

Further, the surface of the comb-shaped electrodes is oxidized or nitrided by plasma containing oxygen or nitrogen as a component.
Alternatively, the comb-shaped electrodes are oxidized by anodic oxidation by a wet method. Thus, for example, if the material of the comb-shaped electrode is aluminum, the surface layer will be aluminum oxide or aluminum nitride, so that the mass of the comb-shaped electrode can be increased. Therefore, the center frequency can be lowered and a predetermined frequency characteristic can be obtained.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method of manufacturing a surface acoustic wave device according to an embodiment of the present invention will be described below with reference to the drawings.

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is provided with a step of detecting frequency characteristics of a method of manufacturing a surface acoustic wave device according to an embodiment of the present invention and a step of sweeping on a comb-shaped electrode by a laser in an atmosphere containing oxygen or nitrogen as a component. Shown device.

The piezoelectric substrate 1 made of quartz has the aluminum comb-shaped electrode 2 formed thereon, and the frequency characteristic is evaluated in step (9) of the flowchart of the manufacturing process of the surface acoustic wave device shown in FIG. The preliminary exhaust chamber 3 is equipped with a vacuum exhaust device 4, a probe 5 for detecting frequency characteristics, and a substrate stage 6. The signal line from the probe 5 is drawn out of the preliminary exhaust chamber 3 without breaking the airtightness of the preliminary exhaust chamber 3 and connected to the frequency characteristic detection device 7. The preliminary evacuation chamber 3 is provided with a gate 8 for taking in and out the quartz piezoelectric substrate 1 on which the aluminum comb-shaped electrode 2 is formed with the outside, and the laser irradiation chamber 9 is the preliminary evacuation chamber 3 A gate 10 is provided for inserting and removing the piezoelectric substrate 1 made of quartz crystal on which the aluminum comb-shaped electrode 2 is formed.

In the laser irradiation chamber 9, a substrate stage 11,
Laser 12, optical system 13 for collecting laser light and sweeping on comb-shaped electrode, gas inlet 1 for introducing argon, which is an inert gas of atmospheric gas, and oxygen and nitrogen
4. Evacuation device 15 is provided.

The process will be described below with reference to FIGS. 1, 5, and 6. First, the frequency characteristic of the surface wave device which has been subjected to the step (9) frequency characteristic evaluation shown in FIG. 5 is detected. If it has a predetermined frequency characteristic, it is determined as a non-defective product and the process proceeds to the next step.

Here, if the center frequency is higher than the predetermined frequency characteristic as a result of the characteristic evaluation, the film thickness of the aluminum comb-shaped electrode is smaller than the predetermined film thickness, that is, the mass of the comb-shaped electrode is large, as can be seen from FIG. Since it is small, the following steps shown in FIG.

The quartz piezoelectric substrate 1 on which the aluminum comb-shaped electrode 2 is formed is put into the preliminary exhaust chamber 3 from the gate 8 and mounted on the substrate stage 6. The probe 5 for frequency characteristic detection is brought into contact with the end of the aluminum comb-shaped electrode 2, and the frequency characteristic detection device 7 detects the frequency characteristic, and confirms that the center frequency is high.

After the detection of the frequency characteristic, the probe 5 for detecting the frequency characteristic is separated from the end of the aluminum comb-shaped electrode 2 and the
The chamber 8 is closed, and the preliminary exhaust chamber 3 is vacuum-exhausted by the vacuum exhaust device 4. After reaching a predetermined degree of vacuum, the gate 10 is opened, the quartz piezoelectric substrate 1 having the aluminum comb-shaped electrode 2 formed thereon is mounted on the substrate stage 11, and after mounting, the gate 10 is closed. . The laser irradiation chamber 9 has a vacuum exhaust device 15
Therefore, the vacuum degree is kept at a predetermined level except when the laser is swept.

After introducing a mixed gas of argon and oxygen from the gas inlet 14 and setting a predetermined vacuum degree, laser-1
2 and the optical system 13 are activated to start laser sweeping on the aluminum comb-shaped electrodes (FIG. 1 (b)). Incidentally, the portion where the probe 5 comes into contact is not swept by the laser in order to detect the frequency characteristic. The processing time of the laser sweep is determined by measuring the change in the center frequency of aluminum in advance, and the time for sweeping is determined from the characteristics of the current center frequency.

After the lapse of a predetermined processing time, the laser 12,
The optical system 13 and the gas introduction are stopped, and vacuum exhaust is performed.

After that, the gate 10 is opened, and the quartz piezoelectric substrate 1 on which the aluminum comb-shaped electrode 2 is formed is mounted on the substrate stage 6 of the preliminary exhaust chamber 3, and the mounted gate 10 is mounted. Close. The probe 5 for frequency characteristic detection is brought into contact with the end of the aluminum comb-shaped electrode 2, and the frequency characteristic detection device 7 detects the frequency characteristic (FIG. 1A).

The laser sweep oxidizes the aluminum comb-shaped electrode surface to aluminum oxide, which increases the weight of the comb-shaped electrode and lowers the center frequency. If the predetermined frequency characteristic is not obtained, the above steps are alternately performed again, and when the laser sweep is completed when the predetermined frequency characteristic is reached, the predetermined characteristic can be obtained.

Through the above steps, defective products can be reduced, and a surface wave device having a predetermined frequency characteristic can be obtained, so that the yield rate can be greatly improved.

Furthermore, in the surface acoustic wave device and the method for manufacturing the same of the present embodiment, the surface of the aluminum comb-shaped electrode is oxidized to form an aluminum oxide, so that the surface becomes harder than the surface of aluminum itself. As a result, the reliability of the device against electromigration and stress migration is greatly improved.

Further, when a substrate having an aluminum oxide surface formed thereon and having a comb-shaped electrode formed thereon is packaged, the comb-shaped electrode does not cause an electrical short circuit even if a foreign metal is mixed in, and the reliability is improved. Can be greatly improved.

Further, in the present embodiment, the detection of the frequency characteristic is carried out separately in the pre-evacuation chamber 3 and the laser sweep is carried out in the laser irradiation chamber 9, but each step is carried out in the same processing chamber. You may go with a time lag.

Further, in this embodiment, the step of detecting the frequency characteristic is performed in the preliminary exhaust chamber 3 and the laser sweep is performed in the laser irradiation chamber 9 separately with a time difference. You may perform simultaneously in the same process chamber.

Further, in the present embodiment, the one after the step (9) frequency characteristic evaluation in FIG. 5 is used, but the one after the step (10) wire bonding may be used. Further, the state after the step (7) in which a comb-shaped electrode is formed on the piezoelectric substrate and many surface wave devices are present may be used.

Further, although the present embodiment was carried out in an atmosphere of argon and oxygen, it may be carried out in an atmosphere containing oxygen or nitrogen as a component.

Further, in the present embodiment, only those having high frequency characteristics were selected and processed. However, when forming aluminum for comb-shaped electrodes, a film having a film thickness equal to or less than a predetermined film thickness was formed, and The frequency characteristics may be adjusted by performing the processing of the first embodiment on the device.

Although aluminum is used as the material of the comb-shaped electrodes in this embodiment, other materials such as aluminum, an alloy of aluminum containing copper, tantalum and chromium may be used.

(Embodiment 2) A second embodiment of the present invention will be described below with reference to the drawings.

FIG. 2 shows one step of a method of manufacturing a surface acoustic wave device according to an embodiment of the present invention. FIG. 2 shows an apparatus including a step of detecting a frequency characteristic and a step of oxidizing or nitriding a comb-shaped electrode by plasma containing oxygen or nitrogen as a component.

The piezoelectric substrate 1 made of quartz has the aluminum comb-shaped electrode 2 formed thereon, and the frequency characteristic is evaluated in step (9) in the flowchart of the manufacturing process of the surface acoustic wave device shown in FIG. The preliminary evacuation chamber 16 is equipped with a vacuum evacuation device 17, a probe 18 for detecting frequency characteristics, and a substrate stage 19. The signal line from the probe 18 is drawn out of the preliminary exhaust chamber 16 without destroying the airtightness of the preliminary exhaust chamber 16, and the frequency characteristic detection device 2
Connected to 0.

The pre-evacuation chamber 16 is provided with a gate 21 for loading and unloading the piezoelectric substrate 1 of quartz having the aluminum comb-shaped electrode 2 formed between the pre-evacuation chamber 16 and the outside. And a gate 23 for inserting and removing the quartz crystal piezoelectric substrate 1 on which the aluminum comb-shaped electrode 2 is formed.

In the plasma processing chamber 22, a substrate stage 24 serving as an electrode, an RF power supply 25, a gas inlet 26 for introducing an inert gas of argon, oxygen and nitrogen, a vacuum exhaust device 27, and an insulator 28. It is equipped with. The process will be described below with reference to FIGS. 2, 5, and 6.

First, in FIG. 5, the frequency characteristic of the surface wave device which has been subjected to the step (9) frequency characteristic evaluation is detected. If it has a predetermined frequency characteristic, it is passed to the next step as a non-defective product.

As a result of the evaluation, if the center frequency is higher than the predetermined frequency characteristic, the thickness of the aluminum comb-shaped electrode is smaller than the predetermined film thickness, that is, the mass of the comb-shaped electrode is smaller, as can be seen from FIG. Yes (FIG. 2A) is performed.

The quartz piezoelectric substrate 1 on which the aluminum comb-shaped electrode 2 is formed is put into the preliminary exhaust chamber 16 from the gate 21.
It is mounted on the board stage 19. The probe 18 for detecting the frequency characteristic is brought into contact with the end of the aluminum comb-shaped electrode 2, and the frequency characteristic is detected by the frequency characteristic detecting device 20 to confirm that the center frequency is high. After the frequency characteristic detection is completed, the probe 18 for detecting the frequency characteristic is separated from the end of the aluminum comb-shaped electrode 2, the gate 21 is closed, and the preliminary exhaust chamber 16 is evacuated by the vacuum evacuation device 17. After reaching a predetermined degree of vacuum, the gate 23 is opened, and the quartz piezoelectric substrate 1 on which the aluminum comb-shaped electrode 2 is formed serves as an electrode.
After mounting, the gate 23 is closed.

Incidentally, the portion in contact with the probe 18 for detecting the frequency characteristic is covered with the substrate stage 24 which becomes an electrode, and is not oxidized or nitrided even by the plasma treatment. Further, the plasma processing chamber 22 is maintained at a predetermined vacuum degree by a vacuum exhaust device 27 except during plasma processing. A mixed gas of argon and oxygen is introduced from the gas introduction port 26, and after setting a predetermined vacuum degree, the RF power source 25 is operated to generate plasma. (FIG.2 (b)). The plasma processing time is determined by measuring the change in the center frequency of aluminum in advance and determining the time to be processed from the characteristics of the current center frequency.

After the lapse of a predetermined processing time, the RF power source 25,
Stop gas introduction and evacuate. Then gate 2
3 is opened, the piezoelectric substrate 1 made of quartz on which the aluminum comb-shaped electrode 2 is formed is mounted on the substrate stage 19 of the preliminary exhaust chamber 16, and the gate 23 is closed after mounting. The frequency characteristic detecting probe 18 is brought into contact with the end of the aluminum comb-shaped electrode 2, and the frequency characteristic detecting device 20 detects the frequency characteristic (FIG. 2).
(A)).

The plasma treatment oxidizes the surface of the aluminum comb-shaped electrode to form aluminum oxide, which increases the weight of the comb-shaped electrode and lowers the center frequency. If the predetermined frequency characteristic is not obtained here, the above steps are performed again alternately, and the plasma treatment is terminated when the predetermined frequency characteristic is reached.

Through the above steps, defective products can be reduced and a surface wave device having a predetermined frequency characteristic can be obtained, so that the yield rate can be greatly improved.

Further, in this embodiment, the preliminary exhaust chamber 16
Although the frequency characteristics are detected in the plasma processing chamber 22 by the plasma processing separately, each process may be performed in the same processing chamber with a time difference.

Further, in this embodiment, the preliminary exhaust chamber 16
Although the frequency characteristics are detected in the plasma processing chamber 22 separately with the time difference, the processes may be simultaneously performed in the same processing chamber.

Further, in the present embodiment, the one after the frequency characteristic evaluation of the step (9) of FIG. 5 is used, but the one after the steps (10) and after may be used, and the piezoelectric element may be used. The state after the step (7) in which the comb-shaped electrodes are formed on the body substrate and a large number of surface wave devices are present may be used.

Further, although the treatment with argon and oxygen gas is carried out in the present embodiment, the treatment with a gas containing oxygen or nitrogen as a component is also possible.

Further, in the present embodiment, only those having high frequency characteristics were selected and processed. However, when forming aluminum for comb-shaped electrodes, a film having a film thickness equal to or smaller than a predetermined film thickness was formed, and The frequency characteristic may be adjusted by performing the process of the second embodiment on the device.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to the drawings.

FIG. 3 shows one step of a method of manufacturing a surface acoustic wave device according to an embodiment of the present invention. FIG. 3 shows a step of detecting frequency characteristics and a step of performing anodic oxidation by a wet method.

The piezoelectric substrate 1 made of quartz has the aluminum comb-shaped electrode 2 formed thereon, and the frequency characteristic is evaluated in step (9) of the flowchart of the manufacturing process of the surface acoustic wave device shown in FIG. Probes 29 and 30 for applying a voltage to the comb-shaped electrodes for frequency characteristic detection and anodic oxidation are supporting jigs for fixing the probe 1 to the substrate 1 on which the comb-shaped electrodes are formed, and 31 is a quench for anodic oxidation. An acid aqueous solution tank, 32 is a counter electrode for anodizing treatment, 33 is a power source for anodizing, 34 is a washing tank for washing away citric acid, and 35 is a frequency characteristic detecting device.

The process will be described below with reference to FIGS. 3, 5 and 6. First, in FIG. 5, the frequency characteristic of the surface wave device that has been subjected to the step (9) frequency characteristic evaluation is detected. If it has a predetermined frequency characteristic, it is passed to the subsequent process as a non-defective product.

As a result of the evaluation, if the center frequency is higher than the predetermined frequency characteristic, the film thickness of the aluminum comb-shaped electrode is smaller than the predetermined film thickness, that is, the mass of the comb-shaped electrode is small, as can be seen from FIG. Therefore, the step of FIG. 3A is performed.

The substrate 1 and the probe 29, which are in electrical contact with each other by the supporting jig 30, are immersed in a bath 31 of an aqueous solution of citric acid, and a voltage is applied by a power source 33 between the counter electrode 32 and the counter electrode 32. A voltage is applied to perform anodic oxidation (FIG. 3A). The anodizing treatment time is determined by measuring the change in the center frequency of aluminum in advance and determining the time to be treated from the characteristics of the current center frequency.

After a predetermined processing time has elapsed, the citric acid is removed by immersing it in the cleaning bath 34 (FIG. 3 (b)). Then, the frequency characteristic detection device 35 detects the frequency characteristic. The surface of the aluminum comb-shaped electrode is oxidized by the anodic oxidation treatment to become aluminum oxide, and the weight of the comb-shaped electrode is increased and the center frequency is lowered.

If the predetermined frequency characteristic is not obtained,
Again, the above steps may be performed alternately, and the anodic oxidation may be terminated when a predetermined frequency characteristic is reached.

Through the above steps, defective products are reduced and a surface wave device having a predetermined frequency characteristic is obtained, so that the yield rate can be greatly improved.

Further, although the anodic oxidation and the detection of the frequency characteristic are performed separately in this embodiment, each step may be performed in the same processing bath with a time difference.

Further, in this embodiment, the steps of anodic oxidation and the detection of the frequency characteristic are carried out separately with a time difference, but each step may be carried out simultaneously in the same processing tank.

Further, in this embodiment, the one after the frequency characteristic evaluation in the step (9) of FIG. 5 is used, but the one after the steps (10) and after may be used, and the piezoelectric element may be used. The state after the step (7) in which the comb-shaped electrodes are formed on the body substrate and a large number of surface wave devices are present may be used.

In this embodiment, citric acid was used for anodic oxidation, but other solutions may be used.

Further, in the present embodiment, only those having high frequency characteristics were selected and processed. However, when aluminum for a comb-shaped electrode is formed, a film having a film thickness equal to or less than a predetermined film thickness is formed, and The frequency characteristics may be adjusted by performing the processing of the third embodiment on the device.

[0074]

As described above, according to the present invention, even when the frequency characteristic is not the predetermined one, the surface acoustic wave device having the predetermined frequency characteristic can be adjusted and manufactured. And cost can be reduced.

Furthermore, since the surface of the comb-shaped electrode is oxidized or nitrided to form an oxide or a nitride, which hardens, the reliability of the device against electromigration and stress migration can be greatly improved. Furthermore, when packaging a substrate on which the comb-shaped electrode is formed, the comb-shaped electrode does not cause an electrical short circuit even if a foreign metal is mixed in, and the reliability can be greatly improved.

[Brief description of drawings]

FIG. 1 is a process diagram of a method of manufacturing a surface acoustic wave device according to a first embodiment of the present invention.

FIG. 2 is a process chart of a method of manufacturing a surface acoustic wave device according to a second embodiment of the present invention.

FIG. 3 is a process chart of a method of manufacturing a surface acoustic wave device according to a third embodiment of the present invention.

FIG. 4 is a schematic perspective view of a conventional surface acoustic wave device.

FIG. 5 is a correlation diagram of the film thickness of the aluminum comb-shaped electrode of the conventional surface acoustic wave device and the center frequency.

FIG. 6 is a flowchart of a conventional surface wave device manufacturing process.

[Explanation of symbols]

1 Crystal piezoelectric substrate on which aluminum comb-shaped electrode is formed 2 Aluminum comb-shaped electrode 3 Preliminary exhaust chamber 4 Vacuum exhaust device 5 Probe for frequency characteristic detection device 6 Substrate stage 7 Frequency characteristic detection device 8 Gate 9 Laser irradiation chamber 10 Gate 11 Substrate stage 12 Laser 13 Laser Optical system for collecting light and sweeping on comb-shaped electrode 14 Gas inlet 15 Vacuum exhaust device 16 Preliminary exhaust chamber 17 Vacuum exhaust device 18 Probe for frequency characteristic detection 19 Substrate stage 20 Frequency characteristic detection device 21 Gate 22 Plasma processing chamber 23 Gate 24 Substrate stage to be an electrode 25 RF power supply 26 Gas Inlet 27 Vacuum evacuation device 28 Insulator 29 Probe 30 Support jig 31 Aqueous citric acid solution bath 32 Counter electrode 33 Power supply 34 Cleaning bath 35 Frequency characteristic detection device

Claims (3)

[Claims] 1. A surface wave device in which the surface of a comb-shaped electrode on a piezoelectric substrate is oxidized or nitrided to provide an oxide layer or a nitride layer. 2. A method of manufacturing a surface acoustic wave device having the following steps. (1) Step of forming a comb-shaped electrode on the piezoelectric substrate (2) Step of detecting the frequency characteristic of the surface acoustic wave device after the formation of the comb-shaped electrode (3) According to the detection result of the step (2), oxygen or nitrogen Laser sweeping on the comb electrode in the atmosphere, or oxidizing or nitriding the comb electrode by plasma containing oxygen or nitrogen, or anodizing the comb electrode by a wet method to oxidize or nitride the surface of the comb electrode 3. A step (2) comprising the following steps, wherein the step of oxidizing or nitriding the step (3) is terminated when the frequency characteristic of the surface acoustic wave device reaches a predetermined characteristic. Method of manufacturing surface acoustic wave device. (1) Step of forming a comb-shaped electrode on the piezoelectric substrate (2) Step of detecting the frequency characteristic of the surface acoustic wave device after the formation of the comb-shaped electrode (3) According to the detection result of the step (2), oxygen or nitrogen Laser sweeping on the comb electrode in the atmosphere, or oxidizing or nitriding the comb electrode by plasma containing oxygen or nitrogen, or anodizing the comb electrode by a wet method to oxidize or nitride the surface of the comb electrode