JPH0998052A - Electronic parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the adjustment evaporation value that is caused in the later washing process despite the small adjustment of frequency by forming a frequency adjustment film on a base electrode with limitation given to its area to increase the film thickness in the same mass. SOLUTION: A groove part 14 is formed on a crystal plate 11 by a sandblast method, etc., together with a vibration part 13. A base electrode 12a is led to the rear side of the plate 11 via an electrode lead through-hole 15. Thus the vibrations of the part 13 can be obtained as the electric signals by the electrode 12a and a base electrode 12b formed on the rear side of the plate 11. A space 18 is formed on a mask 17 by etching with no contact secured to the electrode 12a and part 13. In an adjustment evaporation process, an adjustment electrode 16, i.e., a frequency adjustment film is evaporated in an area smaller than that of the electrode 12a. Thus the area of the electrode 16 is limited, so that the thickness of the frequency adjustment film is increased in the same mass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to electronic parts such as crystal oscillators and SAW devices.

[0002]

2. Description of the Related Art A crystal oscillator electrically cuts a crystal vibration by slicing a crystal plate, which is a piezoelectric body, into a predetermined thickness, and forming a base electrode as an excitation electrode on the surface of the vibration part of the crystal plate. Although it can be taken out, the resonance frequency fluctuates due to variations in the thickness of the crystal plate and the thickness of the base electrode.Therefore, in order to compensate for this, an adjustment electrode as a frequency adjustment film is provided on the base electrode. The adjustment vapor deposition step of adjusting the resonance frequency to a desired value is performed by providing the area in a region that is smaller than the formation area by about 100 micrometers. Furthermore, after adjustment vapor deposition, the surface of the crystal plate is cleaned to remove contaminants on the surface of the crystal plate.
At this time, cleaning was performed using an ultrasonic cleaning method together with a detergent.

FIG. 10 shows a conventional crystal oscillator. Reference numeral 1 is a crystal plate, in which a groove portion 4 is hollowed out by a method such as sandblasting, and a vibrating portion 3 is provided. Reference numerals 2a and 2b are base electrodes for exciting an electric signal and serving as an input / output unit. The base electrode 2a is routed to the back side through the electrode routing through hole 5, and the vibration of the vibrating section 3 can be taken out as an electric signal together with the base electrode 2b formed on the back side. On the other hand, FIG. 11 shows a mask used in conventional frequency adjustment vapor deposition. A space 8 is provided in the mask 7 by etching so as not to come into contact with the base electrode 2a and the vibrating portion 3. Reference numeral 9 is an opening of the mask, and the adjustment electrode is formed only in this area.
In the conventional mask, the opening 9 is designed to be smaller than the base electrode 2a by about 100 μm in circumference,
When adjusting vapor deposition, a mask is set as shown in FIG. When the adjustment vapor deposition is performed in this manner, the adjustment electrode is vapor-deposited in a region slightly smaller than the base electrode 2a as shown by 6 in FIG.

[0004]

However, when the amount of adjustment by adjusting the resonance frequency is very small, the value of the resonance frequency is the frequency adjustment vapor deposition when the quartz plate is cleaned by the ultrasonic cleaning method or the like. It changes from the time value. This is because when the amount of adjusted vapor deposition is very small, the amount of vapor deposited is extremely small, so the adhesion to the base becomes extremely weak,
This is because during cleaning, it peels off. Therefore, there has been a problem that until now, only those with a fixed value that is the amount of frequency adjustment or more are good products, and those with less than that are defective products because the frequency is high.

FIG. 13 shows the relationship between the frequency adjustment amount actually performed using a conventional mask and the frequency shift amount after cleaning. According to this, adjustment vapor deposition is performed after frequency adjustment. It can be seen that, for the amount of 500 ppm or less, the frequency changes to the high frequency side after cleaning. This indicates that the amount of the adjusted vapor deposited by cleaning was peeled off.

According to the present invention, even if the amount of frequency adjustment is small,
An object of the present invention is to provide an electronic component that can be adjusted to a target frequency by reducing the amount of adjusted vapor deposition that peels off in the subsequent cleaning step.

[0007]

To achieve the above object, the present invention provides a base electrode on the surface of a piezoelectric substrate,
An electronic component in which a frequency adjusting film is formed on the base electrode, wherein the frequency adjusting film is provided in a region smaller than the formation region of the base electrode, and the film thickness is increased when the mass is the same. It is characterized in that it is formed by limiting the area.

Here, in order to form the frequency adjusting film by limiting the region so that the film thickness becomes thicker when the mass is the same, the area to be vapor-deposited during frequency adjustment is smaller than usual. Make the mask opening smaller. At this time, it is desirable that the opening portion has a shape that does not affect the electrical characteristics later.

[0009]

With the above structure, since the thickness of the frequency adjustment film can be increased, even if the adjustment amount of the frequency is small, the adjustment deposition amount that peels off in the subsequent cleaning step is small, and even when the adjustment deposition amount is very small, Since the frequency is less likely to change in the cleaning process after the adjusted vapor deposition, even a product with a small amount of frequency adjustment, which has been considered as a defective product up to now, can be a good product.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a diaphragm portion of a crystal unit according to an embodiment of the present invention. Reference numeral 11 is a crystal plate, and the groove portion 14 is hollowed out by a method such as sandblasting.
3 are provided. Reference numeral 12a is a base electrode for exciting an electric signal and serving as an input / output unit. The base electrode 12a is routed to the back side through the electrode routing through hole 15, and the vibration of the vibrating portion 13 can be taken out as an electric signal together with the base electrode 12b formed on the back side.
FIG. 2 shows a mask used in the frequency adjustment vapor deposition of this embodiment. A space 18 is provided in the mask 17 by etching so as not to come into contact with the base electrode 12a and the vibrating portion 13. 19 is an opening of the mask,
The adjustment electrode is formed only in this region. When adjusting vapor deposition, a mask is set as shown in FIG. When the adjustment vapor deposition is performed in this way, the adjustment electrode as the frequency adjustment film has the base electrode 12 like the portion 16 in FIG.
It is vapor-deposited in an area smaller than a.

Here, it has been found that, after the frequency adjustment, for the adjustment deposition amount of 500 ppm or less, the frequency changes to the high frequency side after cleaning. This is because the amount of the adjusted vapor deposited by cleaning was peeled off. On the other hand, at least the adjusted amount needs to be 500 ppm or more in order to prevent peeling during cleaning. That is, 50 deposits for adjustment deposition are used.
It can be said that when the film thickness is adjusted to 0 ppm, it does not peel off even during cleaning.

In the adjustment vapor deposition, the change in frequency is almost proportional to the product of the film thickness and the area of the adjustment electrode 16 formed on the base electrode 12a, so that if the amount to be adjusted is about 250 ppm. As shown in FIG. 2, the area of the opening 19 of the mask 17 is 1/2,
This adjusted vapor deposition mask 17 is set as shown in FIG. At this time, the area deposited on the base electrode 12a of the crystal plate 11 is half the normal area. Thereby, the base electrode 12a
Since the total mass of the adjustment electrode 16 formed above is half that in the case of a normal opening, the amount of frequency shift is also halved for the same film thickness, and the adjustment amount is 250 ppm.
In such a case, the film thickness of the adjustment electrode 16 is about twice as large as that in the conventional case. This corresponds to the adjustment amount of 500 ppm when the conventional mask for the opening is used, so that the film thickness of the adjustment electrode 16 can sufficiently withstand the subsequent cleaning.

Similarly, when the adjustment amount is 100 ppm, the same effect can be obtained by setting the size of the opening of the mask to ⅕ so that the film thickness becomes five times.

In the above embodiment, the shape of the opening 19 of the mask 17 is rectangular. However, when the adjustment amount is extremely small, the adjustment electrode 16 is unevenly formed on the base electrode 12. Therefore, the electric characteristics of the crystal unit may be affected. Therefore, in such a case, the mask 17 having the comb-teeth-shaped opening 22 shown in FIG.
5. A comb-teeth-shaped adjusting electrode using the above, a mask 17 having a spiral opening 22 shown in FIG. 5, and a spiral adjusting electrode using the mask 17 having a mesh-like opening 22 shown in FIG.
Adjustment electrode using a mask, a mask 17 having a plurality of circular openings 22 shown in FIG. 7 and an island shape adjustment using a mask 17 having a plurality of long hole-shaped openings 22 shown in FIG. The electrodes for use may be formed.

When the adjustment electrode is vapor-deposited by these masks, the formation region is uniformly provided on the base electrode 12a, so that the electrical characteristics of the crystal unit are not affected. At this time, the formation regions do not need to be regularly arranged, but may be dispersed without being biased.

Further, although the crystal oscillator has been described in the above embodiment, it is also effective in the SAW device. In the case of a SAW device, as shown in FIG. 9, a region smaller than the region where the excitation electrode 24 is formed on the piezoelectric substrate 23 is used as an adjustment region 25, and silicon oxide or the like is used as a frequency adjustment film in this region 25. Constitutes the insulator of. In this case, by adjusting the frequency by using the mask opening changed according to the adjustment amount, it is possible to increase the thickness of the frequency adjustment film even when the frequency adjustment amount is very small. It is possible to form a strong film that can withstand such cleaning.

[0017]

As described above, according to the present invention, the frequency adjustment film provided on the base electrode is formed by limiting the region so that the film thickness becomes large when the mass is the same. However, even if it is small, the amount of adjusted vapor deposition that peels off in the subsequent cleaning step is small. Therefore, even if the adjusted deposition amount is small, the frequency does not change in the cleaning process after the adjusted deposition is performed, and even a small amount of the frequency adjustment amount, which was previously considered a defective product, is considered a good product. can do.

[Brief description of drawings]

FIG. 1 is a plan view showing a vibrating plate portion of a crystal unit according to an embodiment of the present invention.

FIG. 2 is a plan view showing a mask used when forming an adjustment electrode of the crystal unit.

FIG. 3 is a cross-sectional view when forming the adjustment electrode.

FIG. 4 is a plan view showing another example of the mask.

FIG. 5 is a plan view showing another example of the mask.

FIG. 6 is a plan view showing another example of the mask.

FIG. 7 is a plan view showing another example of the mask.

FIG. 8 is a plan view showing another example of the mask.

FIG. 9 is a perspective view showing a SAW device which is another embodiment of the present invention.

FIG. 10 is a plan view showing a diaphragm portion of a conventional crystal unit.

FIG. 11 is a plan view showing a mask that has been used when forming an adjustment electrode of the crystal unit.

FIG. 12 is a cross-sectional view of the adjustment electrode when being formed.

FIG. 13 is a correlation diagram showing the relationship between the adjustment amount after the adjustment vapor deposition and the frequency shift amount after cleaning in the crystal unit.

[Explanation of symbols]

 1,11 Quartz plate 2a, 2b, 12a, 12b Base electrode 3,13 Vibrating part 4,14 Groove part 5,15 Through hole for electrode routing 6,16 Adjustment electrode 7,17 Mask 8,18 Electrode escape space 9,19 Opening 22 Opening 23 Piezoelectric Substrate 24 Excitation Electrode 25 Adjustment Area

Claims (6)

[Claims] 1. A base electrode is provided on the surface of a piezoelectric substrate,
An electronic component in which a frequency adjusting film is formed on the base electrode, wherein the frequency adjusting film is provided in a region smaller than the formation region of the base electrode, and the film thickness is increased when the mass is the same. An electronic component formed by limiting the area. 2. An electronic component comprising a base electrode provided on the surface of a substrate made of a piezoelectric material, and an input / output electrode composed of an adjustment electrode provided on the electrode, wherein the adjustment electrode is the above-mentioned electrode. An electronic component that is provided in a region smaller than the region where the base electrode is formed and is formed by limiting the region so that the film thickness increases when the mass is the same. 3. The electronic component according to claim 2, wherein the region where the adjustment electrode is formed is comb-shaped. 4. The electronic component according to claim 2, wherein a region where the adjustment electrode is formed has a spiral shape. 5. The electronic component according to claim 2, wherein a region where the adjustment electrode is formed has a mesh shape. 6. The electronic component according to claim 2, wherein a region where the adjustment electrode is formed has an island shape.